Articles de revues : « Arthropodes – Reproduction (biologie) »

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Pascar, Jane, et Christopher H. Chandler. « A bioinformatics approach to identifyingWolbachiainfections in arthropods ». PeerJ 6 (3 septembre 2018) : e5486. http://dx.doi.org/10.7717/peerj.5486.

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Wolbachiais the most widespread endosymbiont, infecting >20% of arthropod species, and capable of drastically manipulating the host’s reproductive mechanisms. Conventionally, diagnosis has relied on PCR amplification; however, PCR is not always a reliable diagnostic technique due to primer specificity, strain diversity, degree of infection and/or tissue sampled. Here, we look for evidence ofWolbachiainfection across a wide array of arthropod species using a bioinformatic approach to detect theWolbachiagenesftsZ, wsp,and thegroEoperon in next-generation sequencing samples available through the NCBI Sequence Read Archive. For samples showing signs of infection, we attempted to assemble entireWolbachiagenomes, and in order to better understand the relationships between hosts and symbionts, phylogenies were constructed using the assembled gene sequences. Out of the 34 species with positively identified infections, eight species of arthropod had not previously been recorded to harborWolbachiainfection. All putative infections cluster with known representative strains belonging to supergroup A or B, which are known to only infect arthropods. This study presents an efficient bioinformatic approach for post-sequencing diagnosis and analysis ofWolbachiainfection in arthropods.

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Johnson, Marc T. J., Mark Vellend et John R. Stinchcombe. « Evolution in plant populations as a driver of ecological changes in arthropod communities ». Philosophical Transactions of the Royal Society B : Biological Sciences 364, n^o 1523 (12 juin 2009) : 1593–605. http://dx.doi.org/10.1098/rstb.2008.0334.

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Heritable variation in traits can have wide-ranging impacts on species interactions, but the effects that ongoing evolution has on the temporal ecological dynamics of communities are not well understood. Here, we identify three conditions that, if experimentally satisfied, support the hypothesis that evolution by natural selection can drive ecological changes in communities. These conditions are: (i) a focal population exhibits genetic variation in a trait(s), (ii) there is measurable directional selection on the trait(s), and (iii) the trait(s) under selection affects variation in a community variable(s). When these conditions are met, we expect evolution by natural selection to cause ecological changes in the community. We tested these conditions in a field experiment examining the interactions between a native plant ( Oenothera biennis ) and its associated arthropod community (more than 90 spp.). Oenothera biennis exhibited genetic variation in several plant traits and there was directional selection on plant biomass, life-history strategy (annual versus biennial reproduction) and herbivore resistance. Genetically based variation in biomass and life-history strategy consistently affected the abundance of common arthropod species, total arthropod abundance and arthropod species richness. Using two modelling approaches, we show that evolution by natural selection in large O. biennis populations is predicted to cause changes in the abundance of individual arthropod species, increases in the total abundance of arthropods and a decline in the number of arthropod species. In small O. biennis populations, genetic drift is predicted to swamp out the effects of selection, making the evolution of plant populations unpredictable. In short, evolution by natural selection can play an important role in affecting the dynamics of communities, but these effects depend on several ecological factors. The framework presented here is general and can be applied to other systems to examine the community-level effects of ongoing evolution.

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Sterkel, Marcos, et Pedro L. Oliveira. « Developmental roles of tyrosine metabolism enzymes in the blood-sucking insect Rhodnius prolixus ». Proceedings of the Royal Society B : Biological Sciences 284, n^o 1854 (3 mai 2017) : 20162607. http://dx.doi.org/10.1098/rspb.2016.2607.

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The phenylalanine/tyrosine degradation pathway is frequently described as a catabolic pathway that funnels aromatic amino acids into citric acid cycle intermediates. Previously, we demonstrated that the accumulation of tyrosine generated during the hydrolysis of blood meal proteins in Rhodnius prolixus is potentially toxic, a harmful outcome that is prevented by the action of the first two enzymes in the tyrosine degradation pathway. In this work, we further evaluated the relevance of all other enzymes involved in phenylalanine/tyrosine metabolism in the physiology of this insect. The knockdown of most of these enzymes produced a wide spectrum of distinct phenotypes associated with reproduction, development and nymph survival, demonstrating a highly pleiotropic role of tyrosine metabolism. The phenotypes obtained for two of these enzymes, homogentisate dioxygenase and fumarylacetoacetase, have never before been described in any arthropod. To our knowledge, this report is the first comprehensive gene-silencing analysis of an amino acid metabolism pathway in insects. Amino acid metabolism is exceptionally important in haematophagous arthropods due to their particular feeding behaviour.

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Wang, He, Renate Matzke-Karasz, David J. Horne, Xiangdong Zhao, Meizhen Cao, Haichun Zhang et Bo Wang. « Exceptional preservation of reproductive organs and giant sperm in Cretaceous ostracods ». Proceedings of the Royal Society B : Biological Sciences 287, n^o 1935 (16 septembre 2020) : 20201661. http://dx.doi.org/10.1098/rspb.2020.1661.

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The bivalved crustacean ostracods have the richest fossil record of any arthropod group and display complex reproductive strategies contributing to their evolutionary success. Sexual reproduction involving giant sperm, shared by three superfamilies of living ostracod crustaceans, is among the most fascinating behaviours. However, the origin and evolution of this reproductive mechanism has remained largely unexplored because fossil preservation of such features is extremely rare. Here, we report exceptionally preserved ostracods with soft parts (appendages and reproductive organs) in a single piece of mid-Cretaceous Kachin amber (approximately 100 Myr old). The ostracod assemblage is composed of 39 individuals. Thirty-one individuals belong to a new species and genus, Myanmarcypris hui gen. et sp. nov., exhibiting an ontogenetic sequence from juveniles to adults (male and female). Seven individuals are assigned to Thalassocypria sp. (Cypridoidea, Candonidae, Paracypridinae) and one to Sanyuania sp. (Cytheroidea, Loxoconchidae). Our micro-CT reconstruction provides direct evidence of the male clasper, sperm pumps (Zenker organs), hemipenes, eggs and female seminal receptacles with giant sperm. Our results reveal that the reproduction behavioural repertoire, which is associated with considerable morphological adaptations, has remained unchanged over at least 100 million years—a paramount example of evolutionary stasis. These results also double the age of the oldest unequivocal fossil animal sperm. This discovery highlights the capacity of amber to document invertebrate soft parts that are rarely recorded by other depositional environments.

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Zhang, Qiang, Wei Dou, Clauvis Nji Tizi Taning, Shan-Shan Yu, Guo-Rui Yuan, Feng Shang, Guy Smagghe et Jin-Jun Wang. « miR-309a is a regulator of ovarian development in the oriental fruit fly Bactrocera dorsalis ». PLOS Genetics 18, n^o 9 (16 septembre 2022) : e1010411. http://dx.doi.org/10.1371/journal.pgen.1010411.

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Fecundity is arguably one of the most important life history traits, as it is closely tied to fitness. Most arthropods are recognized for their extreme reproductive capacity. For example, a single female of the oriental fruit fly Bactrocera dorsalis, a highly invasive species that is one of the most destructive agricultural pests worldwide, can lay more than 3000 eggs during its life span. The ovary is crucial for insect reproduction and its development requires further investigation at the molecular level. We report here that miR-309a is a regulator of ovarian development in B. dorsalis. Our bioinformatics and molecular studies have revealed that miR-309a binds the transcription factor pannier (GATA-binding factor A/pnr), and this activates yolk vitellogenin 2 (Vg 2) and vitellogenin receptor (VgR) advancing ovarian development. We further show that miR-309a is under the control of juvenile hormone (JH) and independent from 20-hydroxyecdysone. Thus, we identified a JH-controlled miR-309a/pnr axis that regulates Vg2 and VgR to control the ovarian development. This study has further enhanced our understanding of molecular mechanisms governing ovarian development and insect reproduction. It provides a background for identifying targets for controlling important Dipteran pests.

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Liana, Marcin, et Wojciech Witaliński. « Microorganisms in the oribatid mite Hermannia gibba (C. L. Koch, 1839) (Acari : Oribatida : Hermanniidae) ». Biological Letters 47, n^o 1 (1 janvier 2010) : 37–43. http://dx.doi.org/10.2478/v10120-009-0018-9.

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Microorganisms in the oribatid mite Hermannia gibba (C. L. Koch, 1839) (Acari: Oribatida: Hermanniidae) Symbiotic microorganisms associated with arthropods are known to play a significant role in the life of their hosts. Most commonly, the symbionts improve their host's food digestion and modify their meiosis/reproduction. The usual mode of parent-to-offspring transmission of the symbionts is transovarial transmission (vertical) via oocytes. Using transmission electron microscopy, we found extracellular yeast-like and bacteroid microorganisms in food boli, as well as intracellular symbiotic bacteria within cells of the digestive tract and in reproductive cells in both sexes of the oribatid mite Hermannia gibba. In the digestive tract, the scarce bacteria were lying individually within midgut cells. The bacteria observed in developing oocytes were numerous and formed large aggregates close to the nuclear envelope and clusters of mitochondria. In spermatocytes we found a few single bacteria located at the cell periphery. The bacteria in the digestive cells may assist in digestion of plant food, whereas the meiotic drive function of the gonad-invading microbes is uncertain. The studied mite species is biparental and its sex ratio is not biased.

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Döll, Katharina, Subhankar Chatterjee, Stefan Scheu, Petr Karlovsky et Marko Rohlfs. « Fungal metabolic plasticity and sexual development mediate induced resistance to arthropod fungivory ». Proceedings of the Royal Society B : Biological Sciences 280, n^o 1771 (22 novembre 2013) : 20131219. http://dx.doi.org/10.1098/rspb.2013.1219.

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Prey organisms do not tolerate predator attack passively but react with a multitude of inducible defensive strategies. Although inducible defence strategies are well known in plants attacked by herbivorous insects, induced resistance of fungi against fungivorous animals is largely unknown. Resistance to fungivory is thought to be mediated by chemical properties of fungal tissue, i.e. by production of toxic secondary metabolites. However, whether fungi change their secondary metabolite composition to increase resistance against arthropod fungivory is unknown. We demonstrate that grazing by a soil arthropod, Folsomia candida , on the filamentous fungus Aspergillus nidulans induces a phenotype that repels future fungivores and retards fungivore growth. Arthropod-exposed colonies produced significantly higher amounts of toxic secondary metabolites and invested more in sexual reproduction relative to unchallenged fungi. Compared with vegetative tissue and asexual conidiospores, sexual fruiting bodies turned out to be highly resistant against fungivory in facultative sexual A. nidulans . This indicates that fungivore grazing triggers co-regulated allocation of resources to sexual reproduction and chemical defence in A. nidulans . Plastic investment in facultative sex and chemical defence may have evolved as a fungal strategy to escape from predation.

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Duplouy, Anne, et Emily A. Hornett. « Uncovering the hidden players in Lepidoptera biology : the heritable microbial endosymbionts ». PeerJ 6 (8 mai 2018) : e4629. http://dx.doi.org/10.7717/peerj.4629.

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The Lepidoptera is one of the most widespread and recognisable insect orders. Due to their remarkable diversity, economic and ecological importance, moths and butterflies have been studied extensively over the last 200 years. More recently, the relationship between Lepidoptera and their heritable microbial endosymbionts has received increasing attention. Heritable endosymbionts reside within the host’s body and are often, but not exclusively, inherited through the female line. Advancements in molecular genetics have revealed that host-associated microbes are both extremely prevalent among arthropods and highly diverse. Furthermore, heritable endosymbionts have been repeatedly demonstrated to play an integral role in many aspects of host biology, particularly host reproduction. Here, we review the major findings of research of heritable microbial endosymbionts of butterflies and moths. We promote the Lepidoptera as important models in the study of reproductive manipulations employed by heritable endosymbionts, with the mechanisms underlying male-killing and feminisation currently being elucidated in moths and butterflies. We also reveal that the vast majority of research undertaken of Lepidopteran endosymbionts concernsWolbachia. While this highly prevalent bacterium is undoubtedly important, studies should move towards investigating the presence of other, and interacting endosymbionts, and we discuss the merits of examining the microbiome of Lepidoptera to this end. We finally consider the importance of understanding the influence of endosymbionts under global environmental change and when planning conservation management of endangered Lepidoptera species.

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Perlman, Steve J., Martha S. Hunter et Einat Zchori-Fein. « The emerging diversity of Rickettsia ». Proceedings of the Royal Society B : Biological Sciences 273, n^o 1598 (21 avril 2006) : 2097–106. http://dx.doi.org/10.1098/rspb.2006.3541.

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The best-known members of the bacterial genus Rickettsia are associates of blood-feeding arthropods that are pathogenic when transmitted to vertebrates. These species include the agents of acute human disease such as typhus and Rocky Mountain spotted fever. However, many other Rickettsia have been uncovered in recent surveys of bacteria associated with arthropods and other invertebrates; the hosts of these bacteria have no relationship with vertebrates. It is therefore perhaps more appropriate to consider Rickettsia as symbionts that are transmitted vertically in invertebrates, and secondarily as pathogens of vertebrates. In this review, we highlight the emerging diversity of Rickettsia species that are not associated with vertebrate pathogenicity. Phylogenetic analysis suggests multiple transitions between symbionts that are transmitted strictly vertically and those that exhibit mixed (horizontal and vertical) transmission. Rickettsia may thus be an excellent model system in which to study the evolution of transmission pathways. We also focus on the emergence of Rickettsia as a diverse reproductive manipulator of arthropods, similar to the closely related Wolbachia , including strains associated with male-killing, parthenogenesis, and effects on fertility. We emphasize some outstanding questions and potential research directions, and suggest ways in which the study of non-pathogenic Rickettsia can advance our understanding of their disease-causing relatives.

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Masui, Shinji, Tetsuhiko Sasaki et Hajime Ishikawa. « Genes for the Type IV Secretion System in an Intracellular Symbiont, Wolbachia, a Causative Agent of Various Sexual Alterations in Arthropods ». Journal of Bacteriology 182, n^o 22 (15 novembre 2000) : 6529–31. http://dx.doi.org/10.1128/jb.182.22.6529-6531.2000.

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ABSTRACT Wolbachia species are intracellular bacteria known to cause reproductive abnormalities in their hosts. In this study, we identified Wolbachia genes encoding homologs to the type IV secretion system by which many pathogenic bacteria secrete macromolecules. The genes identified encoded most of the essential components of the secretion system and were cotranscribed as an operon.

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Huang, Cheng-Wang, Wan-Jun Chen, Xin Ke, Yunhe Li et Yun-Xia Luan. « A multi-generational risk assessment of Cry1F on the non-target soil organism Folsomia candida (Collembola) based on whole transcriptome profiling ». PeerJ 7 (10 mai 2019) : e6924. http://dx.doi.org/10.7717/peerj.6924.

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The Bacillus thuringiensis toxin Cry1F has been used to develop insect-resistant genetically engineered crops. There has been great interest in evaluating its potential risk to non-target organisms (NTOs). However, the majority of previous risk assessments only examined one generation of NTOs using several physiological indicators, which cannot comprehensively detect some potential sub-lethal effects at the molecular level. In this study, we conducted a laboratory-based, multi-generational risk assessment of Cry1F for the collembolan Folsomia candida, an important representative of soil arthropods in terms of survival, reproduction, and differentially expressed genes (DEGs) identified from whole transcriptome profiles. Our results demonstrated that Cry1F was continuously ingested by collembolans over three consecutive generations, but it did not affect the survival or reproduction of F. candida. There were no significant differences in the global gene expression between F. candida—fed diets with and without Cry1F, and no consistent co-expressed DEGs over three generations. In addition, Cry1F did not obviously alter the expression profiles of seven sensitive biological markers. Our composite data indicates that Cry1F had no long-term harmful effects on collembolan F. candida.

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Son, Jae Hak, Brian L. Weiss, Daniela I. Schneider, Kiswend-sida M. Dera, Fabian Gstöttenmayer, Robert Opiro, Richard Echodu et al. « Infection with endosymbiotic Spiroplasma disrupts tsetse (Glossina fuscipes fuscipes) metabolic and reproductive homeostasis ». PLOS Pathogens 17, n^o 9 (16 septembre 2021) : e1009539. http://dx.doi.org/10.1371/journal.ppat.1009539.

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Tsetse flies (Glossina spp.) house a population-dependent assortment of microorganisms that can include pathogenic African trypanosomes and maternally transmitted endosymbiotic bacteria, the latter of which mediate numerous aspects of their host’s metabolic, reproductive, and immune physiologies. One of these endosymbionts, Spiroplasma, was recently discovered to reside within multiple tissues of field captured and laboratory colonized tsetse flies grouped in the Palpalis subgenera. In various arthropods, Spiroplasma induces reproductive abnormalities and pathogen protective phenotypes. In tsetse, Spiroplasma infections also induce a protective phenotype by enhancing the fly’s resistance to infection with trypanosomes. However, the potential impact of Spiroplasma on tsetse’s viviparous reproductive physiology remains unknown. Herein we employed high-throughput RNA sequencing and laboratory-based functional assays to better characterize the association between Spiroplasma and the metabolic and reproductive physiologies of G. fuscipes fuscipes (Gff), a prominent vector of human disease. Using field-captured Gff, we discovered that Spiroplasma infection induces changes of sex-biased gene expression in reproductive tissues that may be critical for tsetse’s reproductive fitness. Using a Gff lab line composed of individuals heterogeneously infected with Spiroplasma, we observed that the bacterium and tsetse host compete for finite nutrients, which negatively impact female fecundity by increasing the length of intrauterine larval development. Additionally, we found that when males are infected with Spiroplasma, the motility of their sperm is compromised following transfer to the female spermatheca. As such, Spiroplasma infections appear to adversely impact male reproductive fitness by decreasing the competitiveness of their sperm. Finally, we determined that the bacterium is maternally transmitted to intrauterine larva at a high frequency, while paternal transmission was also noted in a small number of matings. Taken together, our findings indicate that Spiroplasma exerts a negative impact on tsetse fecundity, an outcome that could be exploited for reducing tsetse population size and thus disease transmission.

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Braig, Henk R., Weiguo Zhou, Stephen L. Dobson et Scott L. O’Neill. « Cloning and Characterization of a Gene Encoding the Major Surface Protein of the Bacterial EndosymbiontWolbachia pipientis ». Journal of Bacteriology 180, n^o 9 (1 mai 1998) : 2373–78. http://dx.doi.org/10.1128/jb.180.9.2373-2378.1998.

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ABSTRACT The maternally inherited intracellular symbiont Wolbachia pipientis is well known for inducing a variety of reproductive abnormalities in the diverse arthropod hosts it infects. It has been implicated in causing cytoplasmic incompatibility, parthenogenesis, and the feminization of genetic males in different hosts. The molecular mechanisms by which this fastidious intracellular bacterium causes these reproductive and developmental abnormalities have not yet been determined. In this paper, we report on (i) the purification of one of the most abundantly expressed Wolbachia proteins from infected Drosophila eggs and (ii) the subsequent cloning and characterization of the gene (wsp) that encodes it. The functionality of the wsp promoter region was also successfully tested in Escherichia coli. Comparison of sequences of this gene from different strains of Wolbachiarevealed a high level of variability. This sequence variation correlated with the ability of certain Wolbachia strains to induce or rescue the cytoplasmic incompatibility phenotype in infected insects. As such, this gene will be a very useful tool forWolbachia strain typing and phylogenetic analysis, as well as understanding the molecular basis of the interaction ofWolbachia with its host.

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Bordenstein, Sarah R., et Seth R. Bordenstein. « Widespread phages of endosymbionts : Phage WO genomics and the proposed taxonomic classification of Symbioviridae ». PLOS Genetics 18, n^o 6 (6 juin 2022) : e1010227. http://dx.doi.org/10.1371/journal.pgen.1010227.

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Wolbachia are the most common obligate, intracellular bacteria in animals. They exist worldwide in arthropod and nematode hosts in which they commonly act as reproductive parasites or mutualists, respectively. Bacteriophage WO, the largest of Wolbachia’s mobile elements, includes reproductive parasitism genes, serves as a hotspot for genetic divergence and genomic rearrangement of the bacterial chromosome, and uniquely encodes a Eukaryotic Association Module with eukaryotic-like genes and an ensemble of putative host interaction genes. Despite WO’s relevance to genome evolution, selfish genetics, and symbiotic applications, relatively little is known about its origin, host range, diversification, and taxonomic classification. Here we analyze the most comprehensive set of 150 Wolbachia and phage WO assemblies to provide a framework for discretely organizing and naming integrated phage WO genomes. We demonstrate that WO is principally in arthropod Wolbachia with relatives in diverse endosymbionts and metagenomes, organized into four variants related by gene synteny, often oriented opposite the putative origin of replication in the Wolbachia chromosome, and the large serine recombinase is an ideal typing tool to distinguish the four variants. We identify a novel, putative lytic cassette and WO’s association with a conserved eleven gene island, termed Undecim Cluster, that is enriched with virulence-like genes. Finally, we evaluate WO-like Islands in the Wolbachia genome and discuss a new model in which Octomom, a notable WO-like Island, arose from a split with WO. Together, these findings establish the first comprehensive Linnaean taxonomic classification of endosymbiont phages, including non-Wolbachia phages from aquatic environments, that includes a new family and two new genera to capture the collective relatedness of these viruses.

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Bordenstein, Sarah R., et Seth R. Bordenstein. « Widespread phages of endosymbionts : Phage WO genomics and the proposed taxonomic classification of Symbioviridae ». PLOS Genetics 18, n^o 6 (6 juin 2022) : e1010227. http://dx.doi.org/10.1371/journal.pgen.1010227.

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Wolbachia are the most common obligate, intracellular bacteria in animals. They exist worldwide in arthropod and nematode hosts in which they commonly act as reproductive parasites or mutualists, respectively. Bacteriophage WO, the largest of Wolbachia’s mobile elements, includes reproductive parasitism genes, serves as a hotspot for genetic divergence and genomic rearrangement of the bacterial chromosome, and uniquely encodes a Eukaryotic Association Module with eukaryotic-like genes and an ensemble of putative host interaction genes. Despite WO’s relevance to genome evolution, selfish genetics, and symbiotic applications, relatively little is known about its origin, host range, diversification, and taxonomic classification. Here we analyze the most comprehensive set of 150 Wolbachia and phage WO assemblies to provide a framework for discretely organizing and naming integrated phage WO genomes. We demonstrate that WO is principally in arthropod Wolbachia with relatives in diverse endosymbionts and metagenomes, organized into four variants related by gene synteny, often oriented opposite the putative origin of replication in the Wolbachia chromosome, and the large serine recombinase is an ideal typing tool to distinguish the four variants. We identify a novel, putative lytic cassette and WO’s association with a conserved eleven gene island, termed Undecim Cluster, that is enriched with virulence-like genes. Finally, we evaluate WO-like Islands in the Wolbachia genome and discuss a new model in which Octomom, a notable WO-like Island, arose from a split with WO. Together, these findings establish the first comprehensive Linnaean taxonomic classification of endosymbiont phages, including non-Wolbachia phages from aquatic environments, that includes a new family and two new genera to capture the collective relatedness of these viruses.

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Ebani, Valentina Virginia. « Coxiella burnetii Infection in Cats ». Pathogens 12, n^o 12 (2 décembre 2023) : 1415. http://dx.doi.org/10.3390/pathogens12121415.

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Q fever is a zoonotic disease caused by Coxiella burnetii, with farm ruminants being considered the main sources of infection for humans. However, there have been several cases of the disease in people that have been related to domestic cats as well. Cats can become infected through various routes, including ingestion of raw milk, hunting and consuming infected rodents and birds, consumption of contaminated pet food, inhalation of contaminated aerosols and dust, and bites from hematophagous arthropods. Infected cats typically do not show symptoms, but pregnant queens may experience abortion or give birth to weak kittens. Accurate diagnosis using serological and molecular methods is crucial in detecting infected cats, allowing for prompt action with appropriate treatments and preventive measures. Breeders, cattery personnel, veterinarians, and owners should be informed about the risks of C. burnetii infections associated with cats experiencing reproductive disorders.

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Vasanthakumar, Duraikkannu, Amsalingam Roobakkumar, Jasin Rahman, Pandian Kumar, Chandran Sundaravadivelan et Azariah Babu. « Enhancement of the reproductive potential of Mallada boninensis Okamoto (Neuroptera : Chrysopidae), a predator of red spider mite infesting tea : An evaluation of artificial diets ». Archives of Biological Sciences 64, n^o 1 (2012) : 281–85. http://dx.doi.org/10.2298/abs1201281v.

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Green lacewing Mallada boninensis is an important predator of various soft-bodied arthropods, including red spider mites in tea. Efforts were made to develop mass rearing technology for this predator in a cost effective manner. Three combinations of artificial diets (Protinex (AD1), egg yolk (AD2) and royal jelly (AD3) based) were evaluated in comparison with standard diet (Protinex + Honey). All the tested diets influenced the egg-laying capacity of M. boninensis. The egg yolk-based diet resulted in more egg production than the other two diets. Survival of all life stages of M. boninensis was also observed on each diet and no significant difference was noticed. Results revealed that the egg yolk-based diet is the best of the three diet combinations tested in view of high fecundity and survival rate of M. boninensis.

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Martinez, Julien, Lisa Klasson, John J. Welch et Francis M. Jiggins. « Life and Death of Selfish Genes : Comparative Genomics Reveals the Dynamic Evolution of Cytoplasmic Incompatibility ». Molecular Biology and Evolution 38, n^o 1 (14 août 2020) : 2–15. http://dx.doi.org/10.1093/molbev/msaa209.

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Abstract Cytoplasmic incompatibility is a selfish reproductive manipulation induced by the endosymbiont Wolbachia in arthropods. In males Wolbachia modifies sperm, leading to embryonic mortality in crosses with Wolbachia-free females. In females, Wolbachia rescues the cross and allows development to proceed normally. This provides a reproductive advantage to infected females, allowing the maternally transmitted symbiont to spread rapidly through host populations. We identified homologs of the genes underlying this phenotype, cifA and cifB, in 52 of 71 new and published Wolbachia genome sequences. They are strongly associated with cytoplasmic incompatibility. There are up to seven copies of the genes in each genome, and phylogenetic analysis shows that Wolbachia frequently acquires new copies due to pervasive horizontal transfer between strains. In many cases, the genes have subsequently acquired loss-of-function mutations to become pseudogenes. As predicted by theory, this tends to occur first in cifB, whose sole function is to modify sperm, and then in cifA, which is required to rescue the cross in females. Although cif genes recombine, recombination is largely restricted to closely related homologs. This is predicted under a model of coevolution between sperm modification and embryonic rescue, where recombination between distantly related pairs of genes would create a self-incompatible strain. Together, these patterns of gene gain, loss, and recombination support evolutionary models of cytoplasmic incompatibility.

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Styrsky, John D., et Micky D. Eubanks. « Ecological consequences of interactions between ants and honeydew-producing insects ». Proceedings of the Royal Society B : Biological Sciences 274, n^o 1607 (31 octobre 2006) : 151–64. http://dx.doi.org/10.1098/rspb.2006.3701.

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Interactions between ants and honeydew-producing hemipteran insects are abundant and widespread in arthropod food webs, yet their ecological consequences are very poorly known. Ant–hemipteran interactions have potentially broad ecological effects, because the presence of honeydew-producing hemipterans dramatically alters the abundance and predatory behaviour of ants on plants. We review several studies that investigate the consequences of ant–hemipteran interactions as ‘keystone interactions’ on arthropod communities and their host plants. Ant–hemipteran interactions have mostly negative effects on the local abundance and species richness of several guilds of herbivores and predators. In contrast, out of the 30 studies that document the effects of ant–hemipteran interactions on plants, the majority (73%) shows that plants actually benefit indirectly from these interactions. In these studies, increased predation or harassment of other, more damaging, herbivores by hemipteran-tending ants resulted in decreased plant damage and/or increased plant growth and reproduction. The ecological consequences of mutualistic interactions between honeydew-producing hemipterans and invasive ants relative to native ants have rarely been studied, but they may be of particular importance owing to the greater abundance, aggressiveness and extreme omnivory of invasive ants. We argue that ant–hemipteran interactions are largely overlooked and underappreciated interspecific interactions that have strong and pervasive effects on the communities in which they are embedded.

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Amaku, Marcos, Marcelo Nascimento Burattini, Francisco Antonio Bezerra Coutinho, Luis Fernandez Lopez et Eduardo Massad. « Maximum Equilibrium Prevalence of Mosquito-Borne Microparasite Infections in Humans ». Computational and Mathematical Methods in Medicine 2013 (2013) : 1–7. http://dx.doi.org/10.1155/2013/659038.

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To determine the maximum equilibrium prevalence of mosquito-borne microparasitic infections, this paper proposes a general model for vector-borne infections which is flexible enough to comprise the dynamics of a great number of the known diseases transmitted by arthropods. From equilibrium analysis, we determined the number of infected vectors as an explicit function of the model’s parameters and the prevalence of infection in the hosts. From the analysis, it is also possible to derive the basic reproduction number and the equilibrium force of infection as a function of those parameters and variables. From the force of infection, we were able to conclude that, depending on the disease’s structure and the model’s parameters, there is a maximum value of equilibrium prevalence for each of the mosquito-borne microparasitic infections. The analysis is exemplified by the cases of malaria and dengue fever. With the values of the parameters chosen to illustrate those calculations, the maximum equilibrium prevalence found was 31% and 0.02% for malaria and dengue, respectively. The equilibrium analysis demonstrated that there is a maximum prevalence for the mosquito-borne microparasitic infections.

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Weldon, S. R., M. R. Strand et K. M. Oliver. « Phage loss and the breakdown of a defensive symbiosis in aphids ». Proceedings of the Royal Society B : Biological Sciences 280, n^o 1751 (22 janvier 2013) : 20122103. http://dx.doi.org/10.1098/rspb.2012.2103.

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Terrestrial arthropods are often infected with heritable bacterial symbionts, which may themselves be infected by bacteriophages. However, what role, if any, bacteriophages play in the regulation and maintenance of insect–bacteria symbioses is largely unknown. Infection of the aphid Acyrthosiphon pisum by the bacterial symbiont Hamiltonella defensa confers protection against parasitoid wasps, but only when H. defensa is itself infected by the phage A. pisum secondary endosymbiont (APSE). Here, we use a controlled genetic background and correlation-based assays to show that loss of APSE is associated with up to sevenfold increases in the intra-aphid abundance of H. defensa . APSE loss is also associated with severe deleterious effects on aphid fitness: aphids infected with H. defensa lacking APSE have a significantly delayed onset of reproduction, lower weight at adulthood and half as many total offspring as aphids infected with phage-harbouring H. defensa , indicating that phage loss can rapidly lead to the breakdown of the defensive symbiosis. Our results overall indicate that bacteriophages play critical roles in both aphid defence and the maintenance of heritable symbiosis.

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Carmichael, Jennifer A., Michael C. Lawrence, Lloyd D. Graham, Patricia A. Pilling, V. Chandana Epa, Leonie Noyce, George Lovrecz et al. « The X-ray Structure of a Hemipteran Ecdysone Receptor Ligand-binding Domain ». Journal of Biological Chemistry 280, n^o 23 (4 avril 2005) : 22258–69. http://dx.doi.org/10.1074/jbc.m500661200.

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The ecdysone receptor is a hormone-dependent transcription factor that plays a central role in regulating the expression of vast networks of genes during development and reproduction in the phylum Arthropoda. The functional receptor is a heterodimer of the two nuclear receptor proteins ecdysone receptor (EcR) and ultraspiracle protein. The receptor is the target of the environmentally friendly bisacylhydrazine insecticides, which are effective against Lepidoptera but not against Hemiptera or several other insect orders. Here we present evidence indicating that much of the selectivity of the bisacylhydrazine insecticides can be studied at the level of their binding to purified ecdysone receptor ligand-binding domain (LBD) heterodimers. We report the crystal structure of the ecdysone receptor LBD heterodimer of the hemipteran Bemisia tabaci (Bt, sweet potato whitefly) in complex with the ecdysone analogue ponasterone A. Although comparison with the corresponding known LBD structure from the lepidopteran Heliothis virescens (Hv) ecdysone receptor revealed the overall mode of ponasterone A binding to be very similar in the two cases, we observed that the BtEcR ecdysteroid-binding pocket is structured differently to that of HvEcR in those parts that are not in contact with ponasterone A. We suggest that these differences in the ligand-binding pocket may provide a molecular basis for the taxonomic order selectivity of bisacylhydrazine insecticides.

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Russell, Shelbi L., Jennie Ruelas Castillo et William T. Sullivan. « Wolbachia endosymbionts manipulate the self-renewal and differentiation of germline stem cells to reinforce fertility of their fruit fly host ». PLOS Biology 21, n^o 10 (24 octobre 2023) : e3002335. http://dx.doi.org/10.1371/journal.pbio.3002335.

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The alphaproteobacterium Wolbachia pipientis infects arthropod and nematode species worldwide, making it a key target for host biological control. Wolbachia-driven host reproductive manipulations, such as cytoplasmic incompatibility (CI), are credited for catapulting these intracellular bacteria to high frequencies in host populations. Positive, perhaps mutualistic, reproductive manipulations also increase infection frequencies, but are not well understood. Here, we identify molecular and cellular mechanisms by which Wolbachia influences the molecularly distinct processes of germline stem cell (GSC) self-renewal and differentiation. We demonstrate that wMel infection rescues the fertility of flies lacking the translational regulator mei-P26 and is sufficient to sustain infertile homozygous mei-P26-knockdown stocks indefinitely. Cytology revealed that wMel mitigates the impact of mei-P26 loss through restoring proper pMad, Bam, Sxl, and Orb expression. In Oregon R files with wild-type fertility, wMel infection elevates lifetime egg hatch rates. Exploring these phenotypes through dual-RNAseq quantification of eukaryotic and bacterial transcripts revealed that wMel infection rescues and offsets many gene expression changes induced by mei-P26 loss at the mRNA level. Overall, we show that wMel infection beneficially reinforces host fertility at mRNA, protein, and phenotypic levels, and these mechanisms may promote the emergence of mutualism and the breakdown of host reproductive manipulations.

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Hyder, Moazam, Abdul Mubeen Lodhi, Zhaohong Wang, Aslam Bukero, Jing Gao et Runqian Mao. « Wolbachia Interactions with Diverse Insect Hosts : From Reproductive Modulations to Sustainable Pest Management Strategies ». Biology 13, n^o 3 (27 février 2024) : 151. http://dx.doi.org/10.3390/biology13030151.

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Effective in a variety of insect orders, including dipteran, lepidopteran, and hemipteran, Wolbachia-based control tactics are investigated, noting the importance of sterile and incompatible insect techniques. Encouraging approaches for controlling Aedes mosquitoes are necessary, as demonstrated by the evaluation of a new SIT/IIT combination and the incorporation of SIT into Drosophila suzukii management. For example, Wolbachia may protect plants from rice pests, demonstrating its potential for agricultural biological vector management. Maternal transmission and cytoplasmic incompatibility dynamics are explored, while Wolbachia phenotypic impacts on mosquito and rice pest management are examined. The importance of host evolutionary distance is emphasised in recent scale insect research that addresses host-shifting. Using greater information, a suggested method for comprehending Wolbachia host variations in various contexts emphasises ecological connectivity. Endosymbionts passed on maternally in nematodes and arthropods, Wolbachia are widely distributed around the world and have evolved both mutualistic and parasitic traits. Wolbachia is positioned as a paradigm for microbial symbiosis due to advancements in multiomics, gene functional assays, and its effect on human health. The challenges and opportunities facing Wolbachia research include scale issues, ecological implications, ethical conundrums, and the possibility of customising strains through genetic engineering. It is thought that cooperative efforts are required to include Wolbachia-based therapies into pest management techniques while ensuring responsible and sustainable ways.

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Terretaz, Kévin, Béatrice Horard, Mylène Weill, Benjamin Loppin et Frédéric Landmann. « Functional analysis of Wolbachia Cid effectors unravels cooperative interactions to target host chromatin during replication ». PLOS Pathogens 19, n^o 3 (16 mars 2023) : e1011211. http://dx.doi.org/10.1371/journal.ppat.1011211.

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Wolbachia are common bacteria among terrestrial arthropods. These endosymbionts transmitted through the female germline manipulate their host reproduction through several mechanisms whose most prevalent form called Cytoplasmic Incompatibility -CI- is a conditional sterility syndrome eventually favoring the infected progeny. Upon fertilization, the sperm derived from an infected male is only compatible with an egg harboring a compatible Wolbachia strain, this sperm leading otherwise to embryonic death. The Wolbachia Cif factors CidA and CidB responsible for CI and its neutralization function as a Toxin-Antitoxin system in the mosquito host Culex pipiens. However, the mechanism of CidB toxicity and its neutralization by the CidA antitoxin remain unexplored. Using transfected insect cell lines to perform a structure-function analysis of these effectors, we show that both CidA and CidB are chromatin interactors and CidA anchors CidB to the chromatin in a cell-cycle dependent-manner. In absence of CidA, the CidB toxin localizes to its own chromatin microenvironment and acts by preventing S-phase completion, independently of its deubiquitylase -DUB- domain. Experiments with transgenic Drosophila show that CidB DUB domain is required together with CidA during spermatogenesis to stabilize the CidA-CidB complex. Our study defines CidB functional regions and paves the way to elucidate the mechanism of its toxicity.

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Himmel, Nathaniel J., Thomas R. Gray et Daniel N. Cox. « Phylogenetics Identifies Two Eumetazoan TRPM Clades and an Eighth TRP Family, TRP Soromelastatin (TRPS) ». Molecular Biology and Evolution 37, n^o 7 (5 avril 2020) : 2034–44. http://dx.doi.org/10.1093/molbev/msaa065.

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Abstract Transient receptor potential melastatins (TRPMs) are most well known as cold and menthol sensors, but are in fact broadly critical for life, from ion homeostasis to reproduction. Yet, the evolutionary relationship between TRPM channels remains largely unresolved, particularly with respect to the placement of several highly divergent members. To characterize the evolution of TRPM and like channels, we performed a large-scale phylogenetic analysis of >1,300 TRPM-like sequences from 14 phyla (Annelida, Arthropoda, Brachiopoda, Chordata, Cnidaria, Echinodermata, Hemichordata, Mollusca, Nematoda, Nemertea, Phoronida, Priapulida, Tardigrada, and Xenacoelomorpha), including sequences from a variety of recently sequenced genomes that fill what would otherwise be substantial taxonomic gaps. These findings suggest: 1) the previously recognized TRPM family is in fact two distinct families, including canonical TRPM channels and an eighth major previously undescribed family of animal TRP channel, TRP soromelastatin; 2) two TRPM clades predate the last bilaterian–cnidarian ancestor; and 3) the vertebrate–centric trend of categorizing TRPM channels as 1–8 is inappropriate for most phyla, including other chordates.

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Iturbe-Ormaetxe, Iñaki, Gaelen R. Burke, Markus Riegler et Scott L. O'Neill. « Distribution, Expression, and Motif Variability of Ankyrin Domain Genes in Wolbachia pipientis ». Journal of Bacteriology 187, n^o 15 (1 août 2005) : 5136–45. http://dx.doi.org/10.1128/jb.187.15.5136-5145.2005.

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ABSTRACT The endosymbiotic bacterium Wolbachia pipientis infects a wide range of arthropods, in which it induces a variety of reproductive phenotypes, including cytoplasmic incompatibility (CI), parthenogenesis, male killing, and reversal of genetic sex determination. The recent sequencing and annotation of the first Wolbachia genome revealed an unusually high number of genes encoding ankyrin domain (ANK) repeats. These ANK genes are likely to be important in mediating the Wolbachia-host interaction. In this work we determined the distribution and expression of the different ANK genes found in the sequenced Wolbachia wMel genome in nine Wolbachia strains that induce different phenotypic effects in their hosts. A comparison of the ANK genes of wMel and the non-CI-inducing wAu Wolbachia strain revealed significant differences between the strains. This was reflected in sequence variability in shared genes that could result in alterations in the encoded proteins, such as motif deletions, amino acid insertions, and in some cases disruptions due to insertion of transposable elements and premature stops. In addition, one wMel ANK gene, which is part of an operon, was absent in the wAu genome. These variations are likely to affect the affinity, function, and cellular location of the predicted proteins encoded by these genes.

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Gebrezgiher, Genet B., Rhodes H. Makundi, Abdul A. S. Katakweba, Steven R. Belmain, Charles M. Lyimo et Yonas Meheretu. « Arthropod Ectoparasites of Two Rodent Species Occurring in Varied Elevations on Tanzania’s Second Highest Mountain ». Biology 12, n^o 3 (2 mars 2023) : 394. http://dx.doi.org/10.3390/biology12030394.

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Climate change causes organisms, including species that act as parasite reservoirs and vectors, to shift their distribution to higher altitudes, affecting wildlife infestation patterns. We studied how ectoparasite distributions varied with altitude using two rodent species, Montemys delectorum and Rhabdomys dilectus, at different elevations (1500–3500 m). The ectoparasites infesting the two rodent species were influenced by the host sex, species, and temperature. We expected host density to predict parasite infestation patterns, because hosts in higher densities should have more parasites due to increased contact between individuals. However, temperature, not host density, affected ectoparasite distribution. Since temperatures decrease with elevation, parasite prevalences and abundances were lower at higher elevations, highlighting that the cold conditions at higher elevations limit reproduction and development—this shows that higher elevation zones are ideal for conservation. The rodents and ectoparasite species described in this study have been reported as vectors of diseases of medical and veterinary importance, necessitating precautions. Moreover, Mount Meru is a refuge for a number of endemic and threatened species on the IUCN Red List. Thus, the parasitic infection can also be an additional risk to these critical species as well as biodiversity in general. Therefore, our study lays the groundwork for future wildlife disease surveillance and biodiversity conservation management actions. The study found a previously uncharacterized mite species in the Mesostigmata group that was previously known to be a parasite of honeybees. Further investigations may shed light into the role of this mite species on Mount Meru.

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Sakamoto, Hironori, Daisuke Kageyama, Sugihiko Hoshizaki et Yukio Ishikawa. « Sex-specific death in the Asian corn borer moth (Ostrinia furnacalis) infected with Wolbachia occurs across larval development ». Genome 50, n^o 7 (juillet 2007) : 645–52. http://dx.doi.org/10.1139/g07-041.

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Maternally inherited endosymbiotic bacteria of the genus Wolbachia induce various kinds of reproductive alterations in their arthropod hosts. In a Wolbachia-infected strain of the adzuki bean borer moth, Ostrinia scapulalis (Lepidoptera: Crambidae), males selectively die during larval development, while females selectively die when Wolbachia are eliminated by antibiotic treatment. We found that naturally occurring Wolbachia in the congener O. furnacalis caused sex-specific lethality similar to that in O. scapulalis. Cytogenetic analyses throughout the entire larval development clarified that the death of males (when infected) and females (when cured) took place mainly during early larval stages. However, some individuals also died after complete formation of larval bodies but before egg hatching, or at late larval stages, even in the penultimate instar. Although the specific timing was highly variable, death of males and females occurred before pupation without exception. The potential association of sex-specific lethality with the sex determination mechanism was also examined and is discussed.

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Ramyasoma, Hewawasam Patuwatha Badathuruge Kalindu Dulanja, Yasanthi Illika Nilmini Silva Gunawardene, Menaka Hapugoda et Ranil Samantha Dassanayake. « Assessment of Developmental and Reproductive Fitness of Dengue-Resistant Transgenic Aedes aegypti and Improvement of Fitness Using Antibiotics ». BioMed Research International 2021 (2 mars 2021) : 1–10. http://dx.doi.org/10.1155/2021/6649038.

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Background. Genetic modification offers opportunities to introduce artificially created molecular defence mechanisms to vector mosquitoes to counter diseases causing pathogens such as the dengue virus, malaria parasite, and Zika virus. RNA interference is such a molecular defence mechanism that could be used for this purpose to block the transmission of pathogens among human and animal populations. In our previous study, we engineered a dengue-resistant transgenic Ae. aegypti using RNAi to turn off the expression of dengue virus serotype genomes to reduce virus transmission, requiring assessment of the fitness of this mosquito with respect to its wild counterpart in the laboratory and semifield conditions. Method. Developmental and reproductive fitness parameters of TM and WM have assessed under the Arthropod Containment Level 2 conditions, and the antibiotic treatment assays were conducted using co-trimoxazole, amoxicillin, and doxycycline to assess the developmental and reproductive fitness parameters. Results. A significant reduction of developmental and reproductive fitness parameters was observed in transgenic mosquito compared to wild mosquitoes. However, it was seen in laboratory-scale studies that the fitness of this mosquito has improved significantly in the presence of antibiotics such as co-trimoxazole, amoxicillin, and doxycycline in their feed. Conclusion. Our data indicate that the transgenic mosquito produced had a reduction of the fitness parameters and it may lead to a subsequent reduction of transgenic vector density over the generations in field applications. However, antibiotics of co-trimoxazole, amoxicillin, and doxycycline have shown the improvement of fitness parameters indicating the usefulness in field release of transgenic mosquitoes.

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Maraun, Mark, Georgia Erdmann, Garvin Schulz, Roy A. Norton, Stefan Scheu et Katja Domes. « Multiple convergent evolution of arboreal life in oribatid mites indicates the primacy of ecology ». Proceedings of the Royal Society B : Biological Sciences 276, n^o 1671 (17 juin 2009) : 3219–27. http://dx.doi.org/10.1098/rspb.2009.0425.

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Frequent convergent evolution in phylogenetically unrelated taxa points to the importance of ecological factors during evolution, whereas convergent evolution in closely related taxa indicates the importance of favourable pre-existing characters (pre-adaptations). We investigated the transitions to arboreal life in oribatid mites (Oribatida, Acari), a group of mostly soil-living arthropods. We evaluated which general force—ecological factors, historical constraints or chance—was dominant in the evolution of arboreal life in oribatid mites. A phylogenetic study of 51 oribatid mite species and four outgroup taxa, using the ribosomal 18S rDNA region, indicates that arboreal life evolved at least 15 times independently. Arboreal oribatid mite species are not randomly distributed in the phylogenetic tree, but are concentrated among strongly sclerotized, sexual and evolutionary younger taxa. They convergently evolved a capitate sensillus, an anemoreceptor that either precludes overstimulation in the exposed bark habitat or functions as a gravity receptor. Sexual reproduction and strong sclerotization were important pre-adaptations for colonizing the bark of trees that facilitated the exploitation of living resources (e.g. lichens) and served as predator defence, respectively. Overall, our results indicate that ecological factors are most important for the observed pattern of convergent evolution of arboreal life in oribatid mites, supporting an adaptationist view of evolution.

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Weyda, F. « Female reproductive system of the first-instar nymphs of Machilis helleri (verh.) (Thysanura : Machilidae) with special reference to the segmental arrangement of ovarioles in arthropods ». International Journal of Insect Morphology and Embryology 18, n^o 2-3 (janvier 1989) : 85–96. http://dx.doi.org/10.1016/0020-7322(89)90018-4.

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Nieguitsila, Adélaïde, Roger Frutos, Catherine Moulia, Nathaly Lhermitte-Vallarino, Odile Bain, Laurent Gavotte et Coralie Martin. « Fitness Cost ofLitomosoides sigmodontisFilarial Infection in Mite Vectors ; Implications of Infected Haematophagous Arthropod Excretory Products in Host-Vector Interactions ». BioMed Research International 2013 (2013) : 1–8. http://dx.doi.org/10.1155/2013/584105.

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Filariae are a leading cause of infections which are responsible for serious dermatological, ocular, and vascular lesions. Infective third stage larvae (L3) are transmitted through the bite of a haematophagous vector.Litomosoides sigmodontisis a well-established model of filariasis in the mouse, with the vector being the miteOrnithonyssus bacoti. The aim of the study was to analyse the filarial infection in mites to determine the consequences of filarial infection in the blood-feeding and the reproduction of mites as well as in the regulation of vector-induced inflammation in the mouse skin. Firstly, L3 are unevenly distributed throughout the host population and the majority of the population harbours a moderate infection (1 to 6 L3). Filarial infection does not significantly affect the probing delay for blood feeding. The number of released protonymphs is lower in infected mites but is not correlated with the L3 burden. Finally, induced excreted proteins from infected mites but not from uninfected mites stimulate TNF-αand the neutrophil-chemoattractant KC production by antigen-presenting cells (APCs). Altogether, these results describe the modification of the mite behavior under filarial infection and suggest that the immunomodulatory capacity of the mite may be modified by the presence of the parasite, hindering its defensive ability towards the vertebrate host.

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Martinez, Julien, Thomas H. Ant, Shivan M. Murdochy, Lily Tong, Ana da Silva Filipe et Steven P. Sinkins. « Genome sequencing and comparative analysis of Wolbachia strain wAlbA reveals Wolbachia-associated plasmids are common ». PLOS Genetics 18, n^o 9 (19 septembre 2022) : e1010406. http://dx.doi.org/10.1371/journal.pgen.1010406.

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Wolbachia are widespread maternally-transmitted bacteria of arthropods that often spread by manipulating their host’s reproduction through cytoplasmic incompatibility (CI). Their invasive potential is currently being harnessed in field trials aiming to control mosquito-borne diseases. Wolbachia genomes commonly harbour prophage regions encoding the cif genes which confer their ability to induce CI. Recently, a plasmid-like element was discovered in wPip, a Wolbachia strain infecting Culex mosquitoes; however, it is unclear how common such extra-chromosomal elements are in Wolbachia. Here we sequenced the complete genome of wAlbA, a strain of the symbiont found in Aedes albopictus, after eliminating the co-infecting and higher density wAlbB strain that previously made sequencing of wAlbA challenging. We show that wAlbA is associated with two new plasmids and identified additional Wolbachia plasmids and related chromosomal islands in over 20% of publicly available Wolbachia genome datasets. These plasmids encode a variety of accessory genes, including several phage-like DNA packaging genes as well as genes potentially contributing to host-symbiont interactions. In particular, we recovered divergent homologues of the cif genes in both Wolbachia- and Rickettsia-associated plasmids. Our results indicate that plasmids are common in Wolbachia and raise fundamental questions around their role in symbiosis. In addition, our comparative analysis provides useful information for the future development of genetic tools to manipulate and study Wolbachia symbionts.

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Driscoll, Timothy P., Victoria I. Verhoeve, Cassia Brockway, Darin L. Shrewsberry, Mariah Plumer, Spiridon E. Sevdalis, John F. Beckmann et al. « Evolution of Wolbachia mutualism and reproductive parasitism : insight from two novel strains that co-infect cat fleas ». PeerJ 8 (17 décembre 2020) : e10646. http://dx.doi.org/10.7717/peerj.10646.

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Wolbachiae are obligate intracellular bacteria that infect arthropods and certain nematodes. Usually maternally inherited, they may provision nutrients to (mutualism) or alter sexual biology of (reproductive parasitism) their invertebrate hosts. We report the assembly of closed genomes for two novel wolbachiae, wCfeT and wCfeJ, found co-infecting cat fleas (Ctenocephalides felis) of the Elward Laboratory colony (Soquel, CA, USA). wCfeT is basal to nearly all described Wolbachia supergroups, while wCfeJ is related to supergroups C, D and F. Both genomes contain laterally transferred genes that inform on the evolution of Wolbachia host associations. wCfeT carries the Biotin synthesis Operon of Obligate intracellular Microbes (BOOM); our analyses reveal five independent acquisitions of BOOM across the Wolbachia tree, indicating parallel evolution towards mutualism. Alternately, wCfeJ harbors a toxin-antidote operon analogous to the wPip cinAB operon recently characterized as an inducer of cytoplasmic incompatibility (CI) in flies. wCfeJ cinB and three adjacent genes are collectively similar to large modular toxins encoded in CI-like operons of certain Wolbachia strains and Rickettsia species, signifying that CI toxins streamline by fission of large modular toxins. Remarkably, the C. felis genome itself contains two CI-like antidote genes, divergent from wCfeJ cinA, revealing episodic reproductive parasitism in cat fleas and evidencing mobility of CI loci independent of WO-phage. Additional screening revealed predominant co-infection (wCfeT/wCfeJ) amongst C. felis colonies, though fleas in wild populations mostly harbor wCfeT alone. Collectively, genomes of wCfeT, wCfeJ, and their cat flea host supply instances of lateral gene transfers that could drive transitions between parasitism and mutualism.

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Zhang, Hua-Bao, Zheng Cao, Jun-Xue Qiao, Zi-Qian Zhong, Chen-Chen Pan, Chen Liu, Li-Min Zhang et Yu-Feng Wang. « Metabolomics provide new insights into mechanisms of Wolbachia-induced paternal defects in Drosophila melanogaster ». PLOS Pathogens 17, n^o 8 (12 août 2021) : e1009859. http://dx.doi.org/10.1371/journal.ppat.1009859.

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Wolbachia is a group of intracellular symbiotic bacteria that widely infect arthropods and nematodes. Wolbachia infection can regulate host reproduction with the most common phenotype in insects being cytoplasmic incompatibility (CI), which results in embryonic lethality when uninfected eggs fertilized with sperms from infected males. This suggests that CI-induced defects are mainly in paternal side. However, whether Wolbachia-induced metabolic changes play a role in the mechanism of paternal-linked defects in embryonic development is not known. In the current study, we first use untargeted metabolomics method with LC-MS to explore how Wolbachia infection influences the metabolite profiling of the insect hosts. The untargeted metabolomics revealed 414 potential differential metabolites between Wolbachia-infected and uninfected 1-day-old (1d) male flies. Most of the differential metabolites were significantly up-regulated due to Wolbachia infection. Thirty-four metabolic pathways such as carbohydrate, lipid and amino acid, and vitamin and cofactor metabolism were affected by Wolbachia infection. Then, we applied targeted metabolomics analysis with GC-MS and showed that Wolbachia infection resulted in an increased energy expenditure of the host by regulating glycometabolism and fatty acid catabolism, which was compensated by increased food uptake. Furthermore, overexpressing two acyl-CoA catabolism related genes, Dbi (coding for diazepam-binding inhibitor) or Mcad (coding for medium-chain acyl-CoA dehydrogenase), ubiquitously or specially in testes caused significantly decreased paternal-effect egg hatch rate. Oxidative stress and abnormal mitochondria induced by Wolbachia infection disrupted the formation of sperm nebenkern. These findings provide new insights into mechanisms of Wolbachia-induced paternal defects from metabolic phenotypes.

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Nässel, Dick R., et Meet Zandawala. « Hormonal axes in Drosophila : regulation of hormone release and multiplicity of actions ». Cell and Tissue Research 382, n^o 2 (22 août 2020) : 233–66. http://dx.doi.org/10.1007/s00441-020-03264-z.

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Abstract Hormones regulate development, as well as many vital processes in the daily life of an animal. Many of these hormones are peptides that act at a higher hierarchical level in the animal with roles as organizers that globally orchestrate metabolism, physiology and behavior. Peptide hormones can act on multiple peripheral targets and simultaneously convey basal states, such as metabolic status and sleep-awake or arousal across many central neuronal circuits. Thereby, they coordinate responses to changing internal and external environments. The activity of neurosecretory cells is controlled either by (1) cell autonomous sensors, or (2) by other neurons that relay signals from sensors in peripheral tissues and (3) by feedback from target cells. Thus, a hormonal signaling axis commonly comprises several components. In mammals and other vertebrates, several hormonal axes are known, such as the hypothalamic-pituitary-gonad axis or the hypothalamic-pituitary-thyroid axis that regulate reproduction and metabolism, respectively. It has been proposed that the basic organization of such hormonal axes is evolutionarily old and that cellular homologs of the hypothalamic-pituitary system can be found for instance in insects. To obtain an appreciation of the similarities between insect and vertebrate neurosecretory axes, we review the organization of neurosecretory cell systems in Drosophila. Our review outlines the major peptidergic hormonal pathways known in Drosophila and presents a set of schemes of hormonal axes and orchestrating peptidergic systems. The detailed organization of the larval and adult Drosophila neurosecretory systems displays only very basic similarities to those in other arthropods and vertebrates.

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Hale, Rebecca E., Elise Powell, Leila Beikmohamadi et Mara L. Alexander. « Effects of arthropod inquilines on growth and reproductive effort among metacommunities of the purple pitcher plant (Sarracenia purpurea var. montana) ». PLOS ONE 15, n^o 5 (8 mai 2020) : e0232835. http://dx.doi.org/10.1371/journal.pone.0232835.

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Ponton, Fleur, Kenneth Wilson, Andrew Holmes, David Raubenheimer, Katie L. Robinson et Stephen J. Simpson. « Macronutrients mediate the functional relationship between Drosophila and Wolbachia ». Proceedings of the Royal Society B : Biological Sciences 282, n^o 1800 (7 février 2015) : 20142029. http://dx.doi.org/10.1098/rspb.2014.2029.

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Wolbachia are maternally inherited bacterial endosymbionts that naturally infect a diverse array of arthropods. They are primarily known for their manipulation of host reproductive biology, and recently, infections with Wolbachia have been proposed as a new strategy for controlling insect vectors and subsequent human-transmissible diseases. Yet, Wolbachia abundance has been shown to vary greatly between individuals and the magnitude of the effects of infection on host life-history traits and protection against infection is correlated to within-host Wolbachia abundance. It is therefore essential to better understand the factors that modulate Wolbachia abundance and effects on host fitness. Nutrition is known to be one of the most important mediators of host–symbiont interactions. Here, we used nutritional geometry to quantify the role of macronutrients on insect– Wolbachia relationships in Drosophila melanogaster . Our results show fundamental interactions between diet composition, host diet selection, Wolbachia abundance and effects on host lifespan and fecundity. The results and methods described here open a new avenue in the study of insect– Wolbachia relationships and are of general interest to numerous research disciplines, ranging from nutrition and life-history theory to public health.

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Oehlmann, Jörg, Ulrike Schulte-Oehlmann, Werner Kloas, Oana Jagnytsch, Ilka Lutz, Kresten O. Kusk, Leah Wollenberger et al. « A critical analysis of the biological impacts of plasticizers on wildlife ». Philosophical Transactions of the Royal Society B : Biological Sciences 364, n^o 1526 (27 juillet 2009) : 2047–62. http://dx.doi.org/10.1098/rstb.2008.0242.

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This review provides a critical analysis of the biological effects of the most widely used plasticizers, including dibutyl phthalate, diethylhexyl phthalate, dimethyl phthalate, butyl benzyl phthalate and bisphenol A (BPA), on wildlife, with a focus on annelids (both aquatic and terrestrial), molluscs, crustaceans, insects, fish and amphibians. Moreover, the paper provides novel data on the biological effects of some of these plasticizers in invertebrates, fish and amphibians. Phthalates and BPA have been shown to affect reproduction in all studied animal groups, to impair development in crustaceans and amphibians and to induce genetic aberrations. Molluscs, crustaceans and amphibians appear to be especially sensitive to these compounds, and biological effects are observed at environmentally relevant exposures in the low ng l −1 to µg l −1 range. In contrast, most effects in fish (except for disturbance in spermatogenesis) occur at higher concentrations. Most plasticizers appear to act by interfering with the functioning of various hormone systems, but some phthalates have wider pathways of disruption. Effect concentrations of plasticizers in laboratory experiments coincide with measured environmental concentrations, and thus there is a very real potential for effects of these chemicals on some wildlife populations. The most striking gaps in our current knowledge on the impacts of plasticizers on wildlife are the lack of data for long-term exposures to environmentally relevant concentrations and their ecotoxicity when part of complex mixtures. Furthermore, the hazard of plasticizers has been investigated in annelids, molluscs and arthropods only, and given the sensitivity of some invertebrates, effects assessments are warranted in other invertebrate phyla.

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Tscholl, Thomas, Gösta Nachman, Bernhard Spangl, Hanna Charlotte Serve et Andreas Walzer. « Reproducing during Heat Waves : Influence of Juvenile and Adult Environment on Fecundity of a Pest Mite and Its Predator ». Biology 12, n^o 4 (5 avril 2023) : 554. http://dx.doi.org/10.3390/biology12040554.

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The thermal history of arthropod predators and their prey may affect their reproductive performance during heat waves. Thus, a matching juvenile and adult environment should be beneficial as it enables the individuals to acclimate to extreme conditions. Prey fecundity, however, is also affected by a second stressor, namely predation risk. Here, we assessed the impact of extreme and mild heat waves on the reproductive output of acclimated (juvenile and adult heat wave conditions are matching) and non-acclimated females of the biocontrol agent Phytoseiulus persimilis, a predatory mite, and its herbivorous prey, the two-spotted spider mite Tetranychus urticae, on bean leaves. Their escape and oviposition rates and egg sizes were recorded over 10 days. Additionally, ovipositing prey females were exposed to predator cues and heat waves. Acclimation changed the escape rates and egg sizes of both species, whereas fecundity was only influenced by the adult thermal environment via increased egg numbers under extreme heat waves. Acclimation reduced predator and prey escape rates, which were higher for the predator. Pooled over acclimation, both species deposited more but smaller eggs under extreme heat waves. Acclimation dampened this effect in prey eggs, whereas acclimation resulted in smaller female eggs of the predator. Prey deposited larger male and female eggs. Predator cues reduced prey oviposition, but the effect was small compared to the large increase gained under extreme heat waves. We argue that the success of predators in controlling spider mites during heat waves mainly depends on the fates of escaping predators. A permanent absence of predators may result in the numerical dominance of prey.

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Rosenwald, Laura C., Michael I. Sitvarin et Jennifer A. White. « Endosymbiotic Rickettsiella causes cytoplasmic incompatibility in a spider host ». Proceedings of the Royal Society B : Biological Sciences 287, n^o 1930 (8 juillet 2020) : 20201107. http://dx.doi.org/10.1098/rspb.2020.1107.

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Many arthropod hosts are infected with bacterial endosymbionts that manipulate host reproduction, but few bacterial taxa have been shown to cause such manipulations. Here, we show that a bacterial strain in the genus Rickettsiella causes cytoplasmic incompatibility (CI) between infected and uninfected hosts. We first surveyed the bacterial community of the agricultural spider Mermessus fradeorum (Linyphiidae) using high throughput sequencing and found that individual spiders can be infected with up to five different strains of maternally inherited symbiont from the genera Wolbachia , Rickettsia , and Rickettsiella . The Rickettsiella strain was pervasive, found in all 23 tested spider matrilines. We used antibiotic curing to generate uninfected matrilines that we reciprocally crossed with individuals infected only with Rickettsiella . We found that only 13% of eggs hatched when uninfected females were mated with Rickettsiella -infected males; in contrast, at least 83% of eggs hatched in the other cross types. This is the first documentation of Rickettsiella , or any Gammaproteobacteria, causing CI. We speculate that induction of CI may be much more widespread among maternally inherited bacteria than previously appreciated. Further, our results reinforce the importance of thoroughly characterizing and assessing the inherited microbiome before attributing observed host phenotypes to well-characterized symbionts such as Wolbachia .

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Wei, Wen-Ya, Jian-Hua Huang, Fa-Lin Zhou, Qi-Bin Yang, Yun-Dong Li, Song Jiang, Shi-Gui Jiang et Li-Shi Yang. « Identification and Expression Analysis of Dsx and Its Positive Transcriptional Regulation of IAG in Black Tiger Shrimp (Penaeus monodon) ». International Journal of Molecular Sciences 23, n^o 20 (21 octobre 2022) : 12701. http://dx.doi.org/10.3390/ijms232012701.

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Doublesex (Dsx) is a polymorphic transcription factor of the DMRTs family, which is involved in male sex trait development and controls sexual dimorphism at different developmental stages in arthropods. However, the transcriptional regulation of the Dsx gene is largely unknown in decapods. In this study, we reported the cDNA sequence of PmDsx in Penaeus monodon, which encodes a 257 amino acid polypeptide. It shared many similarities with Dsx homologs and has a close relationship in the phylogeny of different species. We demonstrated that the expression of the male sex differentiation gene Dsx was predominantly expressed in the P. monodon testis, and that PmDsx dsRNA injection significantly decreased the expression of the insulin-like androgenic gland hormone (IAG) and male sex-determining gene while increasing the expression of the female sex-determining gene. We also identified a 5′-flanking region of PmIAG that had two potential cis-regulatory elements (CREs) for the PmDsx transcription. Further, the dual-luciferase reporter analysis and truncated mutagenesis revealed that PmDsx overexpression significantly promoted the transcriptional activity of the PmIAG promoter via a specific CRE. These results suggest that PmDsx is engaged in male reproductive development and positively regulates the transcription of the PmIAG by specifically binding upstream of the promoter of the PmIAG. It provides a theoretical basis for exploring the sexual regulation pathway and evolutionary dynamics of Dmrt family genes in P. monodon.

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Kamoda, S., S. Masui, H. Ishikawa et T. Sasaki. « Wolbachia infection and cytoplasmic incompatibility in the cricket Teleogryllus taiwanemma ». Journal of Experimental Biology 203, n^o 16 (15 août 2000) : 2503–9. http://dx.doi.org/10.1242/jeb.203.16.2503.

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Wolbachia are cytoplasmically inherited bacteria found in many arthropods. They induce various reproductive alterations in their hosts, including cytoplasmic incompatibility, thelytokous parthenogenesis, feminization and male-killing. In this study, we examined Wolbachia infection and its effects on the host cricket Teleogryllus taiwanemma. In a phylogenetic study based on the wsp gene coding for a Wolbachia surface protein, the Wolbachia strain harboured by T. taiwanemma was clustered together with those harboured by Laodelphax striatellus, Tribolium confusum, Acraea encedon, Trichogramma deion and Adalia bipunctata. Crossing experiments using the Wolbachia-infected and uninfected strains of cricket showed that the infection is associated with the expression of unidirectional cytoplasmic incompatibility: the egg hatch rate in the incompatible cross between the infected males and uninfected females was 20.3 %. We also examined the distribution of Wolbachia within the host using polymerase chain reaction assays; they were detected in the antennae, heads, forewings, hindwings, testes, ovaries, Malpighian tubules, foot muscles and fat bodies. Quantitative polymerase chain reaction assays showed that the bacterial density was highest in the fat bodies, followed by the ovaries and testes. Wolbachia were not detected in the haemolymph or in mature spermatozoa. The spermatozoa of the infected male may be modified by the presence of Wolbachia during its development. To examine this possibility, we compared the profiles of sperm proteins between the infected and uninfected males using two-dimensional gel electrophoresis. However, no differences in the protein profiles were observed.

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Kiełkiewicz, Małgorzata, Anna Barczak-Brzyżek, Barbara Karpińska et Marcin Filipecki. « Unravelling the Complexity of Plant Defense Induced by a Simultaneous and Sequential Mite and Aphid Infestation ». International Journal of Molecular Sciences 20, n^o 4 (13 février 2019) : 806. http://dx.doi.org/10.3390/ijms20040806.

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In natural and agricultural conditions, plants are attacked by a community of herbivores, including aphids and mites. The green peach aphid and the two-spotted spider mite, both economically important pests, may share the same plant. Therefore, an important question arises as to how plants integrate signals induced by dual herbivore attack into the optimal defensive response. We showed that regardless of which attacker was first, 24 h of infestation allowed for efficient priming of the Arabidopsis defense, which decreased the reproductive performance of one of the subsequent herbivores. The expression analysis of several defense-related genes demonstrated that the individual impact of mite and aphid feeding spread systematically, engaging the salicylic acid (SA) and jasmonic acid (JA) signaling pathways. Interestingly, aphids feeding on the systemic leaf of the plant simultaneously attacked by mites, efficiently reduced the magnitude of the SA and JA activation, whereas mites feeding remotely increased the aphid-induced SA marker gene expression, while the JA-dependent response was completely abolished. We also indicated that the weaker performance of mites and aphids in double infestation essays might be attributed to aliphatic glucosinolates. Our report is the first to provide molecular data on signaling cross-talk when representatives of two distinct taxonomical classes within the phylum Arthropoda co-infest the same plant.

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Duarte, Elves H., Ana Carvalho, Sergio López-Madrigal, João Costa et Luís Teixeira. « Forward genetics in Wolbachia : Regulation of Wolbachia proliferation by the amplification and deletion of an addictive genomic island ». PLOS Genetics 17, n^o 6 (18 juin 2021) : e1009612. http://dx.doi.org/10.1371/journal.pgen.1009612.

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Wolbachia is one of the smost prevalent bacterial endosymbionts, infecting approximately 40% of terrestrial arthropod species. Wolbachia is often a reproductive parasite but can also provide fitness benefits to its host, as, for example, protection against viral pathogens. This protective effect is currently being applied to fight arboviruses transmission by releasing Wolbachia-transinfected mosquitoes. Titre regulation is a crucial aspect of Wolbachia biology. Higher titres can lead to stronger phenotypes and fidelity of transmission but can have a higher cost to the host. Since Wolbachia is maternally transmitted, its fitness depends on host fitness, and, therefore, its cost to the host may be under selection. Understanding how Wolbachia titres are regulated and other aspects of Wolbachia biology has been hampered by the lack of genetic tools. Here we developed a forward genetic screen to identify new Wolbachia over-proliferative mutant variants. We characterized in detail two new mutants, wMelPop2 and wMelOctoless, and show that the amplification or loss of the Octomom genomic region lead to over-proliferation. These results confirm previous data and expand on the complex role of this genomic region in the control of Wolbachia proliferation. Both new mutants shorten the host lifespan and increase antiviral protection. Moreover, we show that Wolbachia proliferation rate in Drosophila melanogaster depends on the interaction between Octomom copy number, the host developmental stage, and temperature. Our analysis also suggests that the life shortening and antiviral protection phenotypes of Wolbachia are dependent on different, but related, properties of the endosymbiont; the rate of proliferation and the titres near the time of infection, respectively. We also demonstrate the feasibility of a novel and unbiased experimental approach to study Wolbachia biology, which could be further adapted to characterize other genetically intractable bacterial endosymbionts.

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Shropshire, J. Dylan, Brittany Leigh et Seth R. Bordenstein. « Symbiont-mediated cytoplasmic incompatibility : what have we learned in 50 years ? » eLife 9 (25 septembre 2020). http://dx.doi.org/10.7554/elife.61989.

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Cytoplasmic incompatibility (CI) is the most common symbiont-induced reproductive manipulation. Specifically, symbiont-induced sperm modifications cause catastrophic mitotic defects in the fertilized embryo and ensuing lethality in crosses between symbiotic males and either aposymbiotic females or females harboring a different symbiont strain. However, if the female carries the same symbiont strain, then embryos develop properly, thereby imparting a relative fitness benefit to symbiont-transmitting mothers. Thus, CI drives maternally-transmitted bacteria to high frequencies in arthropods worldwide. In the past two decades, CI experienced a boom in interest due to its (i) deployment in worldwide efforts to curb mosquito-borne diseases, (ii) causation by bacteriophage genes, cifA and cifB, that modify sexual reproduction, and (iii) important impacts on arthropod speciation. This review serves as a gateway to experimental, conceptual, and quantitative themes of CI and outlines significant gaps in understanding CI’s mechanism that are ripe for investigation from diverse subdisciplines in the life sciences.

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« Interaction and coevolution of plants and arthropods during the Palaeozoic and Mesozoic ». Philosophical Transactions of the Royal Society of London. Series B : Biological Sciences 335, n^o 1274 (29 février 1992) : 129–65. http://dx.doi.org/10.1098/rstb.1992.0016.

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Fossil evidence of terrestrial vascular plant life and terrestrial arthropods exists from the Silurian. Fossil evidence suggests progressive interaction between the two groups through the later Palaeozoic and Mesozoic. In this paper we present data, particularly from plant fossils, concerning several interactions: feeding, shelter, transport and reproduction. Evidence of arthropod feeding includes eaten leaves, borings in plant tissues, wound reaction and leaf mining as well as gut contents and coprolites from the arthropods themselves. We trace the changes in leaf eating behaviour from continuous marginal feeding, common in the Palaeozoic and early Mesozoic to the more abundant interrupted-marginal and non- marginal feeding behaviour on Cretaceous angiosperm leaves. This change may reflect the evolution of chemical defence strategies by the plants but may also reflect the evolution of different mouthpart design in new insect groups. Leaf mines and leaf galls, although known from the Upper Carboniferous, only become common in the Cretaceous, coinciding with the evolution of several new insect groups and plants. Wood boring is recorded, for the first time, from the Lower Carboniferous and becomes common from the Upper Carboniferous. Data from coprolites suggest that spore feeding preceded leaf feeding. Experiments using pteridophytes and living arthropods indicate that some spores remain viable after passing through the gut and hence this feeding habit may have also been advantageous to some early plants for propagule transport. We conclude that there is much evidence in the fossil record suggesting plant-arthropod interaction, but many more observations are required before detailed interpretations concerning coevolution can be made.

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Karr, Tim, Juan Oses, Alma Burlingame et Brian Oliver. « Proteomics and Functional Genomics of the D. grimshawii Sperm and Associated Male Reproductive Tract Tissues ». FASEB Journal 31, S1 (avril 2017). http://dx.doi.org/10.1096/fasebj.31.1_supplement.926.16.

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High throughput shotgun (bottom up) mass spectrometry has become a staple for the study of male reproduction in Drosophila and other diverse taxa. First applied to the Dmel, a growing list of sperm proteomes in mammals and other arthropods is opening up new areas of comparative and functional genomic studies not previously possible. However, very little is known about the proteomes of the associated reproductive tissues, and here we present a proteomic analysis of the D. grimshawii testis (TE), seminal vesicle (SV), accessory gland (AcG) and sperm (SP). These proteomes represent the first comprehensive study of these major components of the Drosophila male reproductive tract. Overall our study identified 4257 total UniProt IDs (1696 TE; 572 SV; 1084 AcG; 687 SP Flybase genes). From this list we obtained 1989 orthologous Dmel IDs for network, genomic and functional analyses. Comparative molecular evolutionary analysis will also be presented demonstating apparent sub‐functionalization of specific GO protein groups. This work establishes a framework for additional studies designed to provide deeper understanding of the evolution of male sexual reproduction traits.

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Thongbuakaew, Tipsuda, Sirirak Mukem, Arada Chaiyamoon, Kanjana Khornchatri, Thanapong Kruangkum, Scott F. Cummins et Prasert Sobhon. « Characterization, expression, and function of the pyrokinins (PKs) in the giant freshwater prawn, Macrobrachium rosenbergii ». Journal of Experimental Biology, 17 mai 2022. http://dx.doi.org/10.1242/jeb.243742.

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Pyrokinins (PKs) are neuropeptides that have been found to regulate a variety of physiological activities including reproduction in various insect and crustacean species. However, the reproductive roles of PKs in the giant freshwater prawn have not yet been investigated. In this study, we identified the MroPK gene from next-generation sequence resources, which encodes a MroPK precursor that shares a high degree of conservation with the C-terminal sequence of FxPRLamide in other arthropods. MroPK is expressed within most tissues, except the hepatopancreas, stomach, and gill. Within developing ovarian tissue, MroPK expression was found to be significantly higher during the early stages (stages 1-2) compared with the late stages (stages 3-4), and could be localized to the oogonia, previtellogenic, and early vitellogenic oocytes. A role for PK in M. rosenbergii reproduction was supported following experimental administration of MroPK to ovarian explant cultures, showing an increase in the productions of progesterone and estradiol and upregulation of steroidogenesis-related genes (3β-HSD and 17β-HSD) and vitellogenin (Vg) expressions. Together, these results support a role for MroPK in regulating ovarian maturation via steroidogenesis.

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