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1
Pannebakker, Bart A., Laas P. Pijnacker, Bas J. Zwaan e Leo W. Beukeboom. "Cytology of Wolbachia-induced parthenogenesis in Leptopilina clavipes (Hymenoptera: Figitidae)". Genome 47, n. 2 (1 aprile 2004): 299–303. http://dx.doi.org/10.1139/g03-137.
Testo completoAbstract (sommario):
Parthenogenesis induced by cytoplasmatically inherited Wolbachia bacteria has been found in a number of arthropod species, mainly Hymenoptera. Previously, two different forms of diploidy restoration have been reported to underlie parthenogenesis induction in Hymenoptera by Wolbachia. Both are a form of gamete duplication, but each differs in their timing. We investigated the cytology of the early embryonic development of a Wolbachia-infected strain of the parasitoid wasp Leptopilina clavipes and compared it with that of an uninfected sexual strain. Both strains have a similar meiosis. In the infected parthenogenetic strain, diploidy is restored by anaphase restitution during the first somatic mitosis, similar to Trichogramma, but not to Muscidifurax. Our results confirm the occurrence of different cytological mechanisms of diploidy restoration associated with parthenogenesis-inducing Wolbachia in the order Hymenoptera.Key words: gamete duplication, Leptopilina clavipes, parthenogenesis, thelytoky, Wolbachia.
2
Gottlieb, Yuval, Einat Zchori-Fein, John H. Werren e Timothy L. Karr. "Diploidy restoration in Wolbachia-infected Muscidifurax uniraptor (Hymenoptera: Pteromalidae)". Journal of Invertebrate Pathology 81, n. 3 (novembre 2002): 166–74. http://dx.doi.org/10.1016/s0022-2011(02)00149-0.
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3
Kirankumar, S., e T. J. Pandian. "Interspecific androgenetic restoration of rosy barb using cadaveric sperm". Genome 47, n. 1 (1 gennaio 2004): 66–73. http://dx.doi.org/10.1139/g03-104.
Testo completoAbstract (sommario):
Interspecific androgenetic rosy barb (Puntius conchonius) was generated using its cadaveric (-20 °C) or fresh sperm to activate nuclear genome inactivated oocytes of gray tiger barb (Puntius tetrazona). UV irradiation was used to inactivate nuclear genome of tiger barb oocytes. Thermal shock restored diploidy of rosy barb in the oocytes of tiger barb. Survival of androgenotes was 14% or 7% when fresh or cadaveric sperm was used. The diploid or haploid nuclear genome of rosy barb, individually or jointly with that of tiger barb, regulated the time sequence of embryonic development in an alien cytoplasm of tiger barb oocytes. Androgenetic males (Y2Y2) attained sexual maturity earlier and had significantly higher gonadosomatic index and sperm concentration, albeit suffering a slight decrease in fertilizing ability. Conversely, androgenetic females (X2X2) suffered extended interspawning period, reduced fecundity, and poor hatchability of their progenies. These results are discussed with respect to their significance for conservation biology.Key words: nuclear genome inactivation, tiger barb, cadaveric sperm, rosy barb, interspecific androgenotes, Tc1 transposon.
4
Wallace, Mark J., Lydia K. Guja, Marie A. Jouault, Kathy A. Fuller, Russell L. Barrett, Siegfried L. Krauss e Matthew D. Barrett. "DNA ploidy variation and distribution in the Lepidosperma costale complex (Cyperaceae): implications for conservation and restoration in a biodiversity hotspot". Australian Journal of Botany 65, n. 2 (2017): 120. http://dx.doi.org/10.1071/bt16197.
Testo completoAbstract (sommario):
Intraspecific ploidy variation is an important component of angiosperm biodiversity; however, this variation is rarely considered in conservation programs. This is of particular concern when conservation activities include augmentation, reintroduction or ecological restoration because there are potentially negative consequences when ploidy variants are unintentionally mixed within populations. We surveyed regional ploidy variation in the Lepidosperma costale Nees species complex (Schoeneae: Cyperaceae) in the South West Australian Floristic Region, an international biodiversity hotspot. Several L. costale sensu lato populations are threatened by iron-ore extraction, including the rare L. gibsonii R.L.Barrett, and these populations are the subject of ecological restoration programs. The DNA ploidy of 2384 individuals from 28 populations across the range of the species complex was determined and four DNA ploidy levels were discovered, namely, diploid, triploid, tetraploid and pentaploid. Diploids and tetraploids were the most common cytotypes and were largely geographically segregated, even at an exhaustively studied contact zone. Triploids were found at a low frequency in two populations. The rarity of triploids suggests substantial interploidy sterility, and that mixing of ploidy variants should, therefore, be avoided when restoring L. costale s.l. populations. These data provide a guide for L. costale s.l. germplasm collection and suggest that polyploidy may be an important driver of diversification in these sedges.
5
Kamps, T. L., D. R. McCarty e C. D. Chase. "Gametophyte Genetics in Zeu mays L.: Dominance of a Restoration-of-Fertility Allele (Rf3) in Diploid Pollen". Genetics 142, n. 3 (1 marzo 1996): 1001–7. http://dx.doi.org/10.1093/genetics/142.3.1001.
Testo completoAbstract (sommario):
Abstract In Zea mays L. plants carrying the S-type of sterility-inducing cytoplasm, male fertility is determined by a gametophytic, nuclear restoration-of-fertility gene. Haploid pollen carrying the fertility-restoring allele (historically designated Rf3) is starch-filled and functional, whereas pollen carrying the nonrestoring allele (historically designated rf3) is shrunken and nonfunctional. Because restoration of fertility occurs in haploid tissue, the dominance relationship of restoring and nonrestoring alleles is unknown. We have tested the dominance relationship of the restoring and nonrestoring alleles at the rf3 locus in diploid pollen. The meiotic mutant elongate was used to generate tetraploid plants carrying both Rf3 and rf3 alleles in the S cytoplasm. These plants shed predominantly starch-filled pollen, consistent with dominance of the restoring allele. Restriction fragment length polymorphisms linked to the rf3 locus demonstrated cotransmission of rf3 and Rf3 alleles through heterozygous diploid pollen, providing conclusive genetic evidence that the restoring allele is the dominant or functional form of this restoration-of-fertility gene. We suggest that other Scytoplasm restorers result from loss-of-function mutations and propose analysis of unreduced gametes as a test of this model.
6
Lerchenmüller, Carolin, Ana Vujic, Sonja Mittag, Annie Wang, Charles P. Rabolli, Chiara Heß, Fynn Betge et al. "Restoration of Cardiomyogenesis in Aged Mouse Hearts by Voluntary Exercise". Circulation 146, n. 5 (2 agosto 2022): 412–26. http://dx.doi.org/10.1161/circulationaha.121.057276.
Testo completoAbstract (sommario):
Background: The human heart has limited capacity to generate new cardiomyocytes and this capacity declines with age. Because loss of cardiomyocytes may contribute to heart failure, it is crucial to explore stimuli of endogenous cardiac regeneration to favorably shift the balance between loss of cardiomyocytes and the birth of new cardiomyocytes in the aged heart. We have previously shown that cardiomyogenesis can be activated by exercise in the young adult mouse heart. Whether exercise also induces cardiomyogenesis in aged hearts, however, is still unknown. Here, we aim to investigate the effect of exercise on the generation of new cardiomyocytes in the aged heart. Methods: Aged (20-month-old) mice were subjected to an 8-week voluntary running protocol, and age-matched sedentary animals served as controls. Cardiomyogenesis in aged hearts was assessed on the basis of 15 N-thymidine incorporation and multi-isotope imaging mass spectrometry. We analyzed 1793 cardiomyocytes from 5 aged sedentary mice and compared these with 2002 cardiomyocytes from 5 aged exercised mice, followed by advanced histology and imaging to account for ploidy and nucleation status of the cell. RNA sequencing and subsequent bioinformatic analyses were performed to investigate transcriptional changes induced by exercise specifically in aged hearts in comparison with young hearts. Results: Cardiomyogenesis was observed at a significantly higher frequency in exercised compared with sedentary aged hearts on the basis of the detection of mononucleated/diploid 15 N-thymidine–labeled cardiomyocytes. No mononucleated/diploid 15 N-thymidine–labeled cardiomyocyte was detected in sedentary aged mice. The annual rate of mononucleated/diploid 15 N-thymidine–labeled cardiomyocytes in aged exercised mice was 2.3% per year. This compares with our previously reported annual rate of 7.5% in young exercised mice and 1.63% in young sedentary mice. Transcriptional profiling of young and aged exercised murine hearts and their sedentary controls revealed that exercise induces pathways related to circadian rhythm, irrespective of age. One known oscillating transcript, however, that was exclusively upregulated in aged exercised hearts, was isoform 1.4 of regulator of calcineurin, whose regulation and functional role were explored further. Conclusions: Our data demonstrate that voluntary running in part restores cardiomyogenesis in aged mice and suggest that pathways associated with circadian rhythm may play a role in physiologically stimulated cardiomyogenesis.
7
Choi, Hae Ri, Kyung A. Cho, Hyun Tae Kang, Jung Bin Lee, Matt Kaeberlein, Yousin Suh, In Kwon Chung e Sang Chul Park. "Restoration of senescent human diploid fibroblasts by modulation of the extracellular matrix". Aging Cell 10, n. 1 (12 gennaio 2011): 148–57. http://dx.doi.org/10.1111/j.1474-9726.2010.00654.x.
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Yasui, George Shigueki, Takafumi Fujimoto e Katsutoshi Arai. "Restoration of the loach, Misgurnus anguillicaudatus, from cryopreserved diploid sperm and induced androgenesis". Aquaculture 308 (gennaio 2010): S140—S144. http://dx.doi.org/10.1016/j.aquaculture.2010.05.041.
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P, VINDHIYA VARMAN. "Breeding behaviour of triploids in back crosses with Arachis hypogaea". Madras Agricultural Journal 88, september (2001): 375–78. http://dx.doi.org/10.29321/maj.10.a00347.
Testo completoAbstract (sommario):
The diploid (2n = 20) wild species of Arachis are the potential sources of resistance to many pests and diseases. The diploid wild sp. A. cardenasii was hybridized with CV. VRI 2 of A. hypogaea (2n = 40) The resultant triploids (2n = 30) were partially fertile. The pollen of the triploids were utilised for back crossing again with A. hypogaea. There were three distinct form of plants obtained in BC1F1. The pollen of the BC1F1 were utilized for back crossing again with A. hypogaea. The resultant BC1F1 were studied. The complete fertility restoration Iwas observed in form I in the immediate back cross, whereas it was observed in the second back cross in form II. Hence, triploids is also a potential source for genetic introgression in groundnut.
10
Sultan Ahamed, A. M. "Embryonic development following microsurgical restoration of the diploid constitution in the human tripronuclear zygote". Fertility and Sterility 104, n. 3 (settembre 2015): e186. http://dx.doi.org/10.1016/j.fertnstert.2015.07.578.
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11
Manning, Thomas J., Weldon Lane, Richard Darren Williams, Matt Cowan, Marcus Diaz, Christopher Adam Slaton, Konnor MacKey et al. "The Use of Microbial Coatings, Nutrients and Chemical Defense Systems in Oyster Restoration". Marine Technology Society Journal 53, n. 4 (1 luglio 2019): 39–54. http://dx.doi.org/10.4031/mtsj.53.4.2.
Testo completoAbstract (sommario):
AbstractMany oyster species are keystone species that help mitigate shoreline erosion, provide habitats for juvenile fishes, and improve water quality. A number of human-driven factors have led to a decline in their populations worldwide. This article focuses on the chemistry of a novel substrate (nutrient-enriched concrete, or NEC) used to induce settlement and colonization of wild diploid oyster spat and is divided into four sections: (1) composition of the bulk material used for oyster restoration, (2) nutrients added to stimulate growth of bacterial and or algal biofilms, (3) nutrients included for the recently settled oyster spat, and (4) the potential use of natural chemical defense systems to control predators and competing marine life. The goal is to develop a material that can be manufactured and used on a large scale.
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Godfree, Robert C., David J. Marshall, Andrew G. Young, Cathy H. Miller e Sarah Mathews. "Empirical evidence of fixed and homeostatic patterns of polyploid advantage in a keystone grass exposed to drought and heat stress". Royal Society Open Science 4, n. 11 (novembre 2017): 170934. http://dx.doi.org/10.1098/rsos.170934.
Testo completoAbstract (sommario):
A long-standing hypothesis in evolutionary biology is that polyploid plants have a fitness advantage over diploids in climatically variable or extreme habitats. Here we provide the first empirical evidence that polyploid advantage in these environments is caused by two distinct processes: homeostatic maintenance of reproductive output under elevated abiotic stress, and fixed differences in seed development. In an outdoor climate manipulation experiment using coastal to inland Australian populations of the perennial grass Themeda triandra Forssk., we found that total output of viable seed in drought- and heat-stressed tetraploid plants was over four times higher than in diploids, despite being equal under more favourable growing conditions. Tetraploids also consistently produced heavier seeds with longer hygroscopic awns, traits which increase propagule fitness in extreme environments. These differences add to fitness benefits associated with broader-scale local adaptation of inland T. triandra populations to drought stress. Our study provides evidence that nucleotypic effects of genome size and increased reproductive flexibility can jointly underlie polyploid advantage in plants in stressful environments, and argue that ploidy can be an important criterion for selecting plant populations for use in genetic rescue, restoration and revegetation projects, including in habitats affected by climate change.
13
Lu, Chunsheng, e Mark Bridgen. "048 FERTILITY RESTORATION OF AN INTERSPECIFIC ALSTROEMERIA HYBRID BY GENETIC MANIPULATIONS IN VITRO". HortScience 29, n. 5 (maggio 1994): 434f—434. http://dx.doi.org/10.21273/hortsci.29.5.434f.
Testo completoAbstract (sommario):
An interspecific hybrid of Alstroemeria aurea × Alstroemeria caryophyllaea was rescued by immature ovule culture and was completely sterile. To restore the fertility of the hybrid, young, vigorous shoots and buds were treated aseptically with three colchicine levels (0.2, 0.4, and 0.6% in DMSO solution) at four treatment durations (6, 12, 18, and 24 hours), before being cultured onto a shoot regeneration medium for regrowth and development. The growth and development of all treated shoots were retarded by the colchicine. New shoots were regenerated from 61% of the surviving cultures after one month. The degree of recovery was not significantly different among treatments, although the highest concentration (0.6%) and the longest time treatment (24 hours) resulted in some morphological abnormalities. Cultures with newly regenerated shoots/buds were able to initiate roots and, eventually, sixty plantlets were transplanted into the greenhouse after acclimatization. Cytological examination of the root tip cells of the plantlets indicated that tetraploids (2n=4x=32) as well as aneuploids plants were generated from the colchicine treatment, whereas all plants from the control were diploids (2n=2x=16). Details explaining cytological changes and the fertility of the colchiploids will be presented.
14
Wang, Richard R. C., Xingfeng Li, Matthew D. Robbins, Steve R. Larson, Shaun B. Bushman, Thomas A. Jones e Aaron Thomas. "DNA sequence-based mapping and comparative genomics of the St genome of Pseudoroegneria spicata (Pursh) Á. Löve versus wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.)". Genome 63, n. 9 (settembre 2020): 445–57. http://dx.doi.org/10.1139/gen-2019-0152.
Testo completoAbstract (sommario):
Bluebunch wheatgrass (referred to as BBWG) [Pseudoroegneria spicata (Pursh) Á. Löve] is an important rangeland Triticeae grass used for forage, conservation, and restoration. This diploid has the basic St genome that occurs also in many polyploid Triticeae species, which serve as a gene reservoir for wheat improvement. Until now, the St genome in diploid species of Pseudoroegneria has not been mapped. Using a double-cross mapping populations, we mapped 230 expressed sequence tag derived simple sequence repeat (EST-SSR) and 3468 genotyping-by-sequencing (GBS) markers to 14 linkage groups (LGs), two each for the seven homologous groups of the St genome. The 227 GBS markers of BBWG that matched those in a previous study helped identify the unclassified seven LGs of the St sub-genome among 21 LGs of Thinopyrum intermedium (Host) Barkworth & D.R. Dewey. Comparisons of GBS sequences in BBWG to whole-genome sequences in bread wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) revealed that the St genome shared a homology of 35% and 24%, a synteny of 86% and 84%, and a collinearity of 0.85 and 0.86, with ABD and H, respectively. This first-draft molecular map of the St genome will be useful in breeding cereal and forage crops.
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Qin, Qinbo, Yuwei Zhou, Chongqing Wang, Minghe Zhang, Huan Qin, Chun Zhao e Shaojun Liu. "Analysis on the Meiosis-Related Gene (Dmc1, Ph1) Expression in Autotriploid Carassius auratus". Marine Biotechnology 21, n. 6 (14 settembre 2019): 753–61. http://dx.doi.org/10.1007/s10126-019-09921-x.
Testo completoAbstract (sommario):
Abstract Triploid is usually considered to be unable to perform normal meiosis due to the abnormal behavior of the three sets of chromosomes. But autotriploid Carassius auratus in the Dongting water system (3n = 150, abbreviated as 3nCC) can perform normal meiosis. In artificial autotriploid Carassius auratus (3n = 150, abbreviated as 3nRR), female individuals undergo normal meiosis and produce mature gametes, while male individuals cannot. To better understand the effects of triploidization on meiosis in fish, we study the structure, methylation level, and expression level of meiosis-related genes (Dmc1, Ph1) in diploid Carassius auratus (2n = 100, abbreviated as 2nCC), Carassius auratus red var.(2n = 100, abbreviated as RCC), 3nCC and 3nRR. The results show that, compared with their diploid ancestors (2nCC and RCC), Dmc1 and Ph1 genes are hypomethylated in all 3nCC and female 3nRR, while are hypermethylated in male 3nRR. Correspondingly, Dmc1 and Ph1 genes are highly expressed in all 3nCC and female 3nRR, while are lowly expressed in male 3nRR. These results indicate that high expression of meiosis-related genes can contribute to restoration of bivalent pairing during meiosis in autotriploid Carassius auratus. This study provides new insights into the effect of DNA methylation on the fertility in triploid fish.
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Makpol, Suzana, Lina Wati Durani, Kien Hui Chua, Yasmin Anum Mohd Yusof e Wan Zurinah Wan Ngah. "Tocotrienol-Rich Fraction Prevents Cell Cycle Arrest and Elongates Telomere Length in Senescent Human Diploid Fibroblasts". Journal of Biomedicine and Biotechnology 2011 (2011): 1–11. http://dx.doi.org/10.1155/2011/506171.
Testo completoAbstract (sommario):
This study determined the molecular mechanisms of tocotrienol-rich fraction (TRF) in preventing cellular senescence of human diploid fibroblasts (HDFs). Primary culture of HDFs at various passages were incubated with 0.5 mg/mL TRF for 24 h. Telomere shortening with decreased telomerase activity was observed in senescent HDFs while the levels of damaged DNA and number of cells in G0/G1phase were increased and S phase cells were decreased. Incubation with TRF reversed the morphology of senescent HDFs to resemble that of young cells with decreased activity of SA-β-gal, damaged DNA, and cells in G0/G1phase while cells in the S phase were increased. Elongated telomere length and restoration of telomerase activity were observed in TRF-treated senescent HDFs. These findings confirmed the ability of tocotrienol-rich fraction in preventing HDFs cellular ageing by restoring telomere length and telomerase activity, reducing damaged DNA, and reversing cell cycle arrest associated with senescence.
17
Hood, Michael E., e Janis Antonovics. "Mating Within the Meiotic Tetrad and the Maintenance of Genomic Heterozygosity". Genetics 166, n. 4 (1 aprile 2004): 1751–59. http://dx.doi.org/10.1093/genetics/166.4.1751.
Testo completoAbstract (sommario):
Abstract Mating among the products of a single meiosis (automixis or meiotic parthenogenesis) is found in diverse groups of plant, animal, and fungal taxa. Restoration of the diploid stage is often strictly controlled and brings together products separated at the first meiotic division. Despite apparent similarities to diploid selfing, the theoretical prediction is that heterozygosity should be maintained on all chromosomes when it is linked to the centromeres and thus also segregates at the first meiotic division. Using the fungus Microbotryum, we directly test this prediction by linear tetrad analysis. The patterns of meiotic segregation for chromosome size variation (electrophoretic karyotypes) and PCR products (AFLP procedures) were determined for Microbotryum lineages native to North America and Europe. Our data reveal a surprisingly dynamic genome that is rich in heterozygosity and where size-dimorphic autosomes are common. The genetic variation agrees with the prediction of centromere-linked heterozygosity. This was observed to the greatest extent in the lineage of Microbotryum native to North America where there was consistent first-division segregation and independent assortment of multiple linkage groups. The data also show properties that distinguish the fungal sex chromosomes from the autosomes in both lineages of Microbotryum. We describe a scenario where the mating system of automixis with first-division restitution is the result of feedback mechanisms to control exposure of genetic load.
18
Colombero, Liliana T., Maureen Moomjy, E. Scott Sills, Zev Rosenwaks e Gianpiero D. Palermo. "The role of structural integrity of the fertilising spermatozoon in early human embryogenesis". Zygote 7, n. 2 (maggio 1999): 157–63. http://dx.doi.org/10.1017/s0967199499000520.
Testo completoAbstract (sommario):
While the fertilising spermatozoon supplies the active centre directing the human zygote's first mitotic division, the relative contributions of the sperm head and tail (as well as the importance of the sperm's general structural integrity) to subsequent developmental processes remain incompletely studied. The sperm nucleus contains paternal chromatin necessary for restoration of a diploid genome, but the functional role of the sperm tail (either attached or dissected) in early human embryonic growth is not known. In this investigation using oocytes donated by in vitro fertilisation patients, human oocytes were injected with isolated sperm heads (n = 73), isolated sperm flagella (n = 11) or both (dissected sperm heads + free sperm tails, n = 26). The formation of bipronucleate zygotes was recorded for each method. Among oocytes surviving injection with isolated sperm heads, 44 of 66 (67%) formed two pronuclei. Of oocytes receiving only sperm tails, 2 of 11 (18%) displayed two pronuclei, but a single polar body was evident in both cases. When dissected spermatozoa parts (head + tail) were jointly injected, 12 of 26 (46%) developed two pronuclei. From embryos resulting from each of these three fertilisation regimes, blastomere biopsies were obtained and subjected to multiprobe fluorescent in situ hybridisation (FISH) analysis to detect mosaicism or aneuploidy arising from these experimental treatments. Only embryos with growth sufficient to permit sampling of at least two blastomeres were evaluated, and FISH analysis was successful in 25 of 29 (86%) embryos tested. Of 12 embryos derived from injection of an isolated sperm head, only one was normal diploid; the remaining 11 were mosaic. Both embryos resulting from injection of an unattached sperm tail were mosaic. Of 11 embryos generated from oocyte injection with sperm head + tail segments, 10 (91%) were mosaic and only one was normal diploid. Results from this study show that injection of isolated sperm segments can permit oocyte activation and bipronuclear formation. However, a high rate of mosaicism in human embryos originating from disrupted sperm or sperm components suggests that more than a ‘sum of parts’ is needed for later development. The structural integrity of the intact fertilising spermatozoon appears to contribute to normal human early embryogenesis.
19
Feng, Jiuhuan, Valerio Primomo, Zenglu Li, Yongping Zhang, Chao-Chien Jan, Lomas Tulsieram e Steven S. Xu. "Physical localization and genetic mapping of the fertility restoration gene Rfo in canola (Brassica napus L.)". Genome 52, n. 4 (aprile 2009): 401–7. http://dx.doi.org/10.1139/g09-016.
Testo completoAbstract (sommario):
The Ogu cytoplasm for male sterility and its fertility restorer gene Rfo in canola ( Brassica napus L.) were originally introgressed from radish ( Raphanus sativus L.) and have been widely used for canola hybrid production and breeding. The objective of this study was to determine the physical location of the Rfo locus in the canola genome using fluorescence in situ hybridization and genetic mapping. For physical localization of the Rfo gene, two bacterial artificial chromosome (BAC) clones, G62 and B420, which were closely linked to the Rfo gene, were used as probes to hybridize with the somatic metaphase chromosomes of a canola hybrid variety, PHI-46 (46H02), containing the Rfo fragment. The results showed that both clones were physically located at the end of one large metacentric chromosome. By simultaneous use of two BAC clones and 45S rDNA repeated sequences as the probes, we demonstrated that the large metacentric chromosome probed with the two BAC clones did not carry 45S rDNA repeated sequences. The chromosome was 3.65 ± 0.74 µm in average length (20 cells) and ranked second in size among the chromosomes without 45S rDNAs. The centromere index of the chromosome (20 cells) was calculated as 43.74 ± 4.19. A comparison with previously reported putative karyotypes of B. napus (AACC) and its diploid ancestors Brassica rapa L. (AA) and Brassica oleracea L. (CC) suggests that the chromosome carrying the Rfo fragment might belong to one of three large metacentric chromosomes of the C genome. Genetic mapping has confirmed the localization of the Rfo fragment to the distal region of linkage group N19, which corresponds to the C genome in B. napus. This study has provided the evidence of the location of the Rfo gene on canola chromosomes and established a basic framework for further physical mapping and manipulation of the gene.
20
Bridgen, Mark. "In Vitro Breeding Techniques for Alstroemeria". HortScience 31, n. 4 (agosto 1996): 694d—694. http://dx.doi.org/10.21273/hortsci.31.4.694d.
Testo completoAbstract (sommario):
Alstroemeria, also known as Lily-of-the-Incas, Inca Lily, or Peruvian Lily, has been bred at the Univ. of Connecticut since 1985. In vitro procedures have been integrated with traditional breeding techniques to create new and exciting cultivars. Embryo culture has been used to generate interspecific, intraspecific, and intergeneric hybrids that would not have been possible with traditional breeding. Somaclonal variation has been used to create new plants from spontaneous and induced mutations, but, in most cases, the plants have not been acceptable commercially. Chromosome doubling with colchicine has been used for fertility restoration of sterile diploids. Somatic embryogenesis has also been studied quite extensively; somatic embryos are easily obtained from zygotic embryos of Alstroemeria. In vitro fertilization procedures are currently being studied in order to hasten embryo development after hybridization has occurred. Because Alstroemeria plants are slow to propagate by traditional rhizome division, micropropagation is used to multiply new cultivars rapidly. Because the production of pathogen-free plants is one of the goals of our breeding and new plant introduction programs, meristem culture and thermotherapy are also being studied. All of these techniques will be described during the workshop.
21
Bugrov, S. N., V. N. Mitrofanov, D. Ya Aleinik, K. V. Kulakova, O. P. Zhivtsov e M. V. Lekishvili. "Peculiarities of Bone Tissue Regeneration at Application of Osteoplastic Material in Experimental Model of Purulent Bone Wound". Vestnik travmatologii i ortopedii imeni N.N. Priorova, n. 2 (30 giugno 2014): 57–63. http://dx.doi.org/10.32414/0869-8678-2014-2-57-63.
Testo completoAbstract (sommario):
Results of study of new osteoplastic material conditionally named «Kombas» were presented. That material consisted of nondemineralized animal collagen in a form of chips impregnated by vascular endothelium growth factor. The first step of experiment included in vitro study of the material was for cytotoxicity in diploid fibroblast cultures of 4-6 passages. At the second step purulent bone wounds were modelled in 36 Chinchilla rabbits. After debridement bone defect in the study group of animals (n=18) was filled with study material, in control group (n=18) the defect was not filled. Radiologic (X-ray, CT) and morphologic examination were performed at terms 1, 2 and 3 months. For objectification of the achieved data integral indices were proposed. Index of bone defect restoration in study group was 70% higher in 1 month, 47 % - in 2 months and 24% - in 3 months, as compared to the control group. In control group the index which characterized the completion of reparative processes exceeded that index in study group by 42% in 2 months and by 54% in 3 month of observation. Study results showed that elaborated material was not cytotoxic, possessed plasticity, marked osteoinductive and osteoconductive properties, as well as an ability to substitute bone tissue defects under conditions of purulent bone cavity in animal experiment.
22
Bugrov, S. N., V. N. Mitrofanov, D. Ya Aleinik, K. V. Kulakova, O. P. Zhivtsov e M. V. Lekishvili. "Peculiarities of Bone Tissue Regeneration at Application of Osteoplastic Material in Experimental Model of Purulent Bone Wound". N.N. Priorov Journal of Traumatology and Orthopedics 21, n. 2 (15 giugno 2014): 57–63. http://dx.doi.org/10.17816/vto20140257-63.
Testo completoAbstract (sommario):
Results of study of new osteoplastic material conditionally named «Kombas» were presented. That material consisted of nondemineralized animal collagen in a form of chips impregnated by vascular endothelium growth factor. The first step of experiment included in vitro study of the material was for cytotoxicity in diploid fibroblast cultures of 4-6 passages. At the second step purulent bone wounds were modelled in 36 Chinchilla rabbits. After debridement bone defect in the study group of animals (n=18) was filled with study material, in control group (n=18) the defect was not filled. Radiologic (X-ray, CT) and morphologic examination were performed at terms 1, 2 and 3 months. For objectification of the achieved data integral indices were proposed. Index of bone defect restoration in study group was 70% higher in 1 month, 47 % - in 2 months and 24% - in 3 months, as compared to the control group. In control group the index which characterized the completion of reparative processes exceeded that index in study group by 42% in 2 months and by 54% in 3 month of observation. Study results showed that elaborated material was not cytotoxic, possessed plasticity, marked osteoinductive and osteoconductive properties, as well as an ability to substitute bone tissue defects under conditions of purulent bone cavity in animal experiment.
23
Markovic, Dejan. "Biocompatibility assessment of glas ionomer cement: Test of cytotoxicity". Serbian Dental Journal 49, n. 3-4 (2002): 75–80. http://dx.doi.org/10.2298/sgs0204075m.
Testo completoAbstract (sommario):
Evaluation o f cytotoxicity is a first step in assessment of dental materials biocompatibility. Necessity for unique criteria in researches resulted in international standard methodology (ISO). The aim of this study was to assess the cytotoxicity of four restorative materials (three glas ionomer cements and one composite material) and to define adventages and disadventages of common ISO methodology for evaluation of this aspect of dental materials biocompatibility. Research was designed according to ISO/TC 106/1995 and ISO/ 10993-5/1994 methodology. Materials used in this investigation were Fuji IILC (GC), Vitiemer (3M), Ionosit fill (DMG-Hamburg), Luxat (DMG-Hamburg). Evaluation of cytotoxicity was carried out on standardized Human Diploid Cell Lung WI-38. Obtained results showed expressive cytotoxic effect of all investigated materials without statisticaly significant difference. Estimation of material biocompatibility and assessment of obtained results can be made only after establishment of correlation with test results. Common ISO methodology is simple for conductance and reproduction, and use of cell cultures in researches is painless, cost effective and without moral or ethical dilemma.
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Zhang, Ying, Yuka Nagata, Guangyao Yu, Hao G. Nguyen, Matthew R. Jones, Paul Toselli, Carl W. Jackson, Masaaki Tatsuka, Kazuo Todokoro e Katya Ravid. "Aberrant quantity and localization of Aurora-B/AIM-1 and survivin during megakaryocyte polyploidization and the consequences of Aurora-B/AIM-1–deregulated expression". Blood 103, n. 10 (15 maggio 2004): 3717–26. http://dx.doi.org/10.1182/blood-2003-09-3365.
Testo completoAbstract (sommario):
Abstract Megakaryocytes skip late anaphase and cytokinesis during endomitosis. We found normal expression and localization of a fundamental regulator of mitosis, Aurora-B/AIM-1, during prophase in polyploidizing mouse bone marrow megakaryocytes. At late anaphase, however, Aurora-B/AIM-1 is absent or mislocalized. Megakaryocytes treated with a proteasome inhibitor display Aurora-B/AIM-1 properly expressed and localized to the midzone, suggesting that protein degradation contributes to this atypical appearance. In contrast, survivin, an Aurora-B/AIM-1 coregulator of mitosis, is not detected at any stage of the endomitotic cell cycle, and in most megakaryocytes proteasome inhibition does not rescue this phenotype. To further explore the importance of reduced Aurora-B/AIM-1 for polyploidization, it was overexpressed in megakaryocytes of transgenic mice. The phenotype includes increased transgenic mRNA, but not protein, in polyploidy megakaryocytes, further suggesting that Aurora-B/AIM-1 is regulated at the protein level. Aurora-B/AIM-1 protein is, however, elevated in diploid transgenic megakaryocytes. Transgenic mice also exhibit enhanced numbers of megakaryocytes with increased proliferative potential, and some mice exhibit mild decreases in ploidy level. Hence, the molecular programming involved in endomitosis is characterized by the mislocalization or absence of at least 2 critical mitotic regulators, Aurora-B/AIM-1 and survivin. Future studies will examine the impact of survivin restoration on mouse megakaryocyte polyploidization.
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Takeshita, Akihiro, Kaori Shinjo, Nozomi Yamakage, Takaaki Ono, Isao Hirano, Kenji Okinaka, Hirotaka Matsui et al. "Reduced Effect of Inotuzumab Ozogamicin (CMC544) on P-Glycoprotein Positive Malignant B Cells and Its Restoration by Multidrug Resistance Modifiers." Blood 110, n. 11 (16 novembre 2007): 2378. http://dx.doi.org/10.1182/blood.v110.11.2378.2378.
Testo completoAbstract (sommario):
Abstract Several new agents have been introduced for the treatment for B cell malignancies (BCM) to overcome resistance to rituximab. Inotuzumab ozogamicin (CMC544), a humanized anti-CD22 mAb conjugated to N-acetyl-g-calicheamicin demethyl hydrazide (NAC-calicheamicin DMH), binds CD22, leading to internalization and delivery of calicheamicin inside the cells. We have been studying gemtuzumab ozogamicin (CMA676), another calicheamicin-conjugated mAb targeting CD33, and we have reported several new findings regarding multi-drug resistance (MDR) and modification of surface antigens. In this study, we attempted to clarify the effect of CMC544 on BCM cells in relation to MDR, and we investigated the restoration effect of the MDR modifier. We also analyzed the effect of CMC544 in relation to CD22 and P-glycoprotein (P-gp) in the samples from BCM. (Materials and Methods) The cell lines used in this study were CD22-positive parental Daudi and Raji, and their P-gp positive sublines, Daudi/MDR and Raji/MDR, respectively. CD22-negative Jurkat, K562 and NB4 cells, and cells obtained from 11 patients with BCM, were also used. CMC544, unconjugated anti-CD22 mAb (G5/44), CMA676, and unconjugated NAC-calicheamicin DMH were kindly provided by Wyeth Pharmaceutical Co., Ltd. The amount of cell surface antigens and P-gp were analyzed by flow cytometry (FCM). For P-gp analysis, cells underwent a reaction with biotinylated MRK16 mAb or with a subclass-matched control mAb and were then stained with streptavidin-Cy-7. P-gp function was determined by intracellular rhodamine-123 (Rh123) accumulation and its enhancement by MDR modifiers, PSC-833 (Novartis) and MS209 (Mitsui), as previously described. The effect of CMC544 was analyzed by cell count, cell viability, and cell cycle distribution on FCM. It was also determined with or without a MDR modifier. Relationships between the CMC544 effect and the amount of P-gp or CD22 were examined statistically. (Results) A dose-dependent, selective cytotoxic effect of CMC544 was observed in cell lines that expressed CD22. CMC544 is not effective on P-gp-expressing MDR sublines, compared with parental cell lines. MDR modifiers restored the cytotoxic effect of CMC544 in P-gp-expressing sublines. In clinical samples, the cytocidal effect of CMC544, estimated from the fraction of cells in the hypo-diploid portion of the cell cycle, was inversely related to the amount of P-gp estimated by MRK16 mAb (P=0.04), and to the P-gp function assessed by intracellular Rh123 accumulation in the presence of PSC833 or MS209 as MDR modifier (P=0.02 and P=0.01, respectively). Additionally, these MDR modifiers reversed CMC544 resistance in P-gp-expressing CD22-positive cells. On the other hand, the cytotoxic effect of CMC544 was positively correlated with the amount of CD22 (P=0.01). (Conclusion) This study demonstrates that the CMC544 effect depends on the amounts of P-gp and CD22. We might be able to predict the clinical effects of this drug based on these factors. The treatment of BCM has progressed extremely rapidly, and we can now select particular drugs more specifically among many promising agents. Our results contribute to the development of new strategies to treat BCM. In CD22-positive BCM with P-gp, combined use of CMC544 and MDR modifiers may be more beneficial.
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Kotini, Andriana, Jeffrey J. Delrow, Timothy A. Graubert, Stephen Nimer e Eirini P. Papapetrou. "Functional Dissection of Chromosome 7q Loss and Haploinsufficient Gene Discovery Using iPSC Models of MDS". Blood 124, n. 21 (6 dicembre 2014): 524. http://dx.doi.org/10.1182/blood.v124.21.524.524.
Testo completoAbstract (sommario):
Abstract Somatic loss of one copy of the long arm of chromosome 7 [del(7q)] is a characteristic cytogenetic abnormality in MDS and other myeloid malignancies, well-recognized for decades and associated with unfavorable prognosis. Despite compelling clinical evidence that the del(7q) holds a key to the pathogenesis of MDS, the mechanism remains elusive. Gene haploinsufficiency has been proposed as a plausible mechanism, but definitive evidence is lacking. Narrowing down the responsible region and identifying the critical genes has proved challenging with existing approaches. Chr7q deletions are typically very large and modeling in the mouse is problematic, as the genomic regions syntenic to the human chr7q are dispersed into 4 different mouse chromosomes. More than one commonly deleted regions (CDRs) have been proposed by physical mapping studies in patient cells. A handful of genes on chr7q have been implicated through candidate gene approaches and knockout studies in the mouse. However, despite the intense efforts, the contribution of the del(7q) to the disease phenotype and the critical gene or genes on chr7q that mediate it remain unclear. To overcome the limitations of existing tools (primary patient cells, mouse models) to study del(7q)-MDS, we developed a new model harnessing reprogramming and genome editing technologies. First we derived del(7q)-, in parallel with isogenic karyotypically normal induced pluripotent stem cells (iPSCs) from bone marrow hematopoietic cells of two MDS patients. By whole exome sequencing, we were able to identify somatic variants of the MDS clone and show that they are present in the del(7q)-MDS-iPSCs, but not in the karyotypically normal iPSCs, which therefore unambiguously originate from residual normal cells. We used these isogenic and fully genetically characterized patient-derived iPSCs to characterize disease-relevant cellular phenotypes specific to the MDS-iPSCs, which included severely reduced hematopoietic potential and clonogenicity and increased apoptosis. We next found that iPSC clones spontaneously acquiring a second copy of chr7q had an in vitro growth advantage, which enabled us to isolate one clone that completely rescued its hematopoietic differentiation ability upon restoration of a diploid dosage of a ~30Mb chr7q telomeric region. This result provides the first definitive evidence that the del(7q) abnormality confers a profound loss of hematopoietic potential and that this defect is mediated through reduced dosage, consistent with haploinsufficiency of one or more genes. To further narrow down the critical region, we developed genome editing technologies to engineer large chromosomal deletions for the first time in human cells. Combining gene targeting with a modified Cre-loxP approach and the CRISPR/Cas9 endonuclease technology, we were able to generate a panel of 12 iPSC lines harboring hemizygous deletions of various defined segments spanning the entire long arm of chr7. By asking which of them recapitulate the MDS hematopoietic phenotype, we were able to “functionally map” the critical segment in a region spanning cytobands q32.3 - q36.1. To identify critical gene(s) on chr7q, we designed a phenotype-rescue screen. We selected 62 candidate haploinsufficient genes on the basis of significantly reduced expression in del(7q)- compared to isogenic normal iPSCs. We constructed a barcoded lentiviral library of these ORFs and performed a pooled library screen for rescue of hematopoiesis in del(7q)-MDS-iPSCs, i.e. enrichment in CD45+ hematopoietic progenitors. We selected the top 6 genes within our region that were found recurrently enriched in at least 2 independent experiments. Four of them could be individually validated: dosage complementation partially rescued hematopoiesis and knockdown studies mimicking haploinsufficiency (50% knockdown) in normal primary CD34+ hematopoietic progenitor cells had a detrimental effect in hematopoiesis. The four genes include EZH2 and LUC7L2 – two genes found to harbor recurrent heterozygous loss-of-function mutations in MDS – as well as two genes with no previously known role in MDS, located in close genomic proximity to the former two. This approach, constituting a new paradigm of functional human genetics with patient-specific iPSCs, can be more broadly applicable to the study of the phenotypic consequences of segmental chromosomal deletions and to haploinsufficient gene discovery. Disclosures No relevant conflicts of interest to declare.
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Attia, Sabry M., Mohammed A. Al‐Hamamah, Mohamed S. M. Attia, Abdulrazaq Alanazi, Sheikh F. Ahmad, Mushtaq A. Ansari, Ahmed Nadeem, Saleh A. Bakheet e Gamaleldin I. Harisa. "Rituximab alleviates increased disomic sperm in DBA/1J mouse models of rheumatoid arthritis via restoration of redox imbalance". Journal of Biochemical and Molecular Toxicology, 9 agosto 2023. http://dx.doi.org/10.1002/jbt.23496.
Testo completoAbstract (sommario):
AbstractCompared to the general population, patients with arthritis have a higher risk of fertility abnormalities, which have deleterious effects on both reproductive function and pregnancy outcomes, especially in patients wishing to conceive. These may be due to the disease itself or those of drug therapies. Despite the increasing use of rituximab in arthritis, limited data are available on its potential to induce aneuploidy in germ cells. Therefore, the aim of the current investigation was to determine if repeated treatment with rituximab affects the incidence of aneuploidy and redox imbalance in arthritic mouse sperm. Mice were treated with 250 mg/kg rituximab once weakly for 3 weeks, and then sperm were sampled 22 days after the last dose of rituximab. Fluorescence in situ hybridization assay with chromosome‐specific DNA probes was used to evaluate the disomic/diploid sperm. Our results showed that rituximab had no aneuploidogenic effect on the meiotic stage of spermatogenesis. Conversely, arthritis induced a significantly high frequency of disomy, and treatment of arthritic mice with rituximab reduced the increased levels of disomic sperm. The occurrence of total diploidy was not significantly different in all groups. Reduced glutathione and8‐hydroxydeoxyguanosine, markers of oxidative stress were significantly altered in arthritic animals, while rituximab treatment restored these changes. Additionally, arthritis severity was reduced after rituximab treatment. We conclude that rituximab may efficiently alleviate the arthritis‐induced effects on male meiosis and avert the higher risk of abnormal reproductive outcomes. Therefore, treating arthritic patients with rituximab may efficiently inhibit the transmission of genetic anomalies induced by arthritis to future generations.
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Ho, David V., Duncan Tormey, Aaron Odell, Aracely A. Newton, Robert R. Schnittker, Diana P. Baumann, William B. Neaves et al. "Post-meiotic mechanism of facultative parthenogenesis in gonochoristic whiptail lizard species". eLife 13 (7 giugno 2024). http://dx.doi.org/10.7554/elife.97035.
Testo completoAbstract (sommario):
Facultative parthenogenesis (FP) has historically been regarded as rare in vertebrates, but in recent years incidences have been reported in a growing list of fish, reptile, and bird species. Despite the increasing interest in the phenomenon, the underlying mechanism and evolutionary implications have remained unclear. A common finding across many incidences of FP is either a high degree of homozygosity at microsatellite loci or low levels of heterozygosity detected in next-generation sequencing data. This has led to the proposal that second polar body fusion following the meiotic divisions restores diploidy and thereby mimics fertilization. Here, we show that FP occurring in the gonochoristic Aspidoscelis species A. marmoratus and A. arizonae results in genome-wide homozygosity, an observation inconsistent with polar body fusion as the underlying mechanism of restoration. Instead, a high-quality reference genome for A. marmoratus and analysis of whole-genome sequencing from multiple FP and control animals reveals that a post-meiotic mechanism gives rise to homozygous animals from haploid, unfertilized oocytes. Contrary to the widely held belief that females need to be isolated from males to undergo FP, females housed with conspecific and heterospecific males produced unfertilized eggs that underwent spontaneous development. In addition, offspring arising from both fertilized eggs and parthenogenetic development were observed to arise from a single clutch. Strikingly, our data support a mechanism for facultative parthenogenesis that removes all heterozygosity in a single generation. Complete homozygosity exposes the genetic load and explains the high rate of congenital malformations and embryonic mortality associated with FP in many species. Conversely, for animals that develop normally, FP could potentially exert strong purifying selection as all lethal recessive alleles are purged in a single generation.
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Bouwmeester, Jessica, Jonathan Daly, E. Michael Henley, Lynne R. Parenti, Diane E. Pitassy e Mary Hagedorn. "Conservation of coral reef fishes: a field-hardy method to cryopreserve spermatogonial cells". Coral Reefs, 10 maggio 2022. http://dx.doi.org/10.1007/s00338-022-02268-1.
Testo completoAbstract (sommario):
AbstractThe biodiversity of marine fishes is threatened globally by climate change and other anthropogenic activities, particularly in coral reef ecosystems. We present a simple, field-hardy method to cryopreserve marine fish gonads, targeting spermatogonial cells (undifferentiated diploid germ cells) with the ultimate goal of permitting recovery of threatened species and populations via gonadal diploid germ cell transplantation technologies. The use of a simplified cryopreservation extender based on L-15 medium resulted in minimal decline in spermatogonial cell viability post-thaw. Moreover, we compared post-cryopreservation viability of sperm and spermatogonial cells from gonads cryopreserved with freshly prepared cryoprotectant and with cryoprotectant prepared in advance and stored at −20 °C. We found no significant difference, suggesting that these solutions may be prepared in advance and frozen, ready for later use. We urge conservation, academic, and regulatory agencies to cryobank fish gonads as part of their sample collection processes to support the biodiversity and security of valuable marine fish resources, alongside other restoration efforts.
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Xu, Xiaowei, Li Yang, Xinyi Deng, Qingwen Xiao, Xu Huang, Chongqing Wang, Yue Zhou et al. "Expression and localization of HPG axis-related genes in Carassius auratus with different ploidy". Frontiers in Endocrinology 15 (12 febbraio 2024). http://dx.doi.org/10.3389/fendo.2024.1336679.
Testo completoAbstract (sommario):
IntroductionIn the Dongting water system, the Carassius auratus (Crucian carp) complex is characterized by the coexistence of diploid forms (2n=100, 2nCC) and polyploidy forms. The diploid (2nCC) and triploid C.auratus (3n=150, 3nCC) had the same fertility levels, reaching sexual maturity at one year. MethodsThe nucleotide sequence, gene expression, methylation, and immunofluorescence of the gonadotropin releasing hormone 2(Gnrh2), Gonadotropin hormone beta(Gthβ), and Gonadotropin-releasing hormone receptor(Gthr) genes pivotal genes of the hypothalamic-pituitary-gonadal (HPG) axis were analyzed. ResultsThe analysis results indicated that Gnrh2, follicle-stimulating hormone receptor(Fshr), and Lethal hybrid rescue(Lhr) genes increased the copy number and distinct structural differentiation in 3nCC compared to that in 2nCC. The transcript levels of HPG axis genes in 3nCC were higher than 2nCC (P<0.05), which could promote the production and secretion of sex steroid hormones conducive to the gonadal development of 3nCC. Meanwhile, the DNA methylation levels in the promoter regions of the HPG axis genes were lower in 3nCC than in 2nCC. These results suggested that methylation of the promoter region had a potential regulatory effect on gene expression after triploidization. Immunofluorescence showed that the localization of the Fshβ, Lhβ, and Fshr genes between 3nCC and 2nCC remained unchanged, ensuring the normal expression of these genes at the corresponding sites after triploidization. DiscussionRelevant research results provide cell and molecular biology evidence for normal reproductive activities such as gonad development and gamete maturation in triploid C. auratus, and contribute to further understanding of the genetic basis for fertility restoration in triploid C. auratus.
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Grossfurthner, Lukas P., Elizabeth R. Milano, Paul A. Hohenlohe, Lisette P. Waits e Bryce A. Richardson. "Population structure and hybridization under contemporary and future climates in a heteroploid foundational shrub species (Artemisia tridentata)". Frontiers in Plant Science 14 (22 maggio 2023). http://dx.doi.org/10.3389/fpls.2023.1155868.
Testo completoAbstract (sommario):
Current and past climatic changes can shift plant climatic niches, which may cause spatial overlap or separation between related taxa. The former often leads to hybridization and introgression, which may generate novel variation and influence the adaptive capacity of plants. An additional mechanism facilitating adaptations to novel environments and an important evolutionary driver in plants is polyploidy as the result of whole genome duplication. Artemisia tridentata (big sagebrush) is a landscape-dominating foundational shrub in the western United States which occupies distinct ecological niches, exhibiting diploid and tetraploid cytotypes. Tetraploids have a large impact on the species’ landscape dominance as they occupy a preponderance of the arid spectrum of A. tridentata range. Three distinct subspecies are recognized, which co-occur in ecotones – the transition zone between two or more distinct ecological niches – allowing for hybridization and introgression. Here we assess the genomic distinctiveness and extent of hybridization among subspecies at different ploidies under both contemporary and predicted future climates. We sampled five transects throughout the western United States where a subspecies overlap was predicted using subspecies-specific climate niche models. Along each transect, we sampled multiple plots representing the parental and the potential hybrid habitats. We performed reduced representation sequencing and processed the data using a ploidy-informed genotyping approach. Population genomic analyses revealed distinct diploid subspecies and at least two distinct tetraploid gene pools, indicating independent origins of the tetraploid populations. We detected low levels of hybridization (2.5%) between the diploid subspecies, while we found evidence for increased admixture between ploidy levels (18%), indicating hybridization has an important role in the formation of tetraploids. Our analyses highlight the importance of subspecies co-occurrence within these ecotones to maintain gene exchange and potential formation of tetraploid populations. Genomic confirmations of subspecies in the ecotones support the subspecies overlap predicted by the contemporary climate niche models. However, future mid-century projections of subspecies niches predict a substantial loss in range and subspecies overlap. Thus, reductions in hybridization potential could affect new recruitment of genetically variable tetraploids that are vital to this species’ ecological role. Our results underscore the importance of ecotone conservation and restoration.
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Wright, Jessica W., Kristian A. Stevens, Paul Hodgskiss e Charles H. Langley. "SNPs in a Large Genomic Scaffold Are Strongly Associated with Cr1R, Major Gene for Resistance to White Pine Blister Rust in Range-Wide Samples of Sugar Pine (Pinus lambertiana)". Plant Disease, 5 maggio 2022. http://dx.doi.org/10.1094/pdis-08-21-1608-re.
Testo completoAbstract (sommario):
Sugar pine, Pinus lambertiana Douglas, is a keystone species of montane forests from Baja California to southern Oregon. Like other North American white pines, populations of sugar pine have been greatly reduced by the disease white pine blister rust (WPBR) caused by a fungal pathogen, Cronartium ribicola, that was introduced into North America early in the twentieth century. Major gene resistance to WPBR segregating in natural populations has been documented in sugar pine. Indeed, the dominant resistance gene in this species, Cr1, was genetically mapped, although not precisely. Genomic single nucleotide polymorphisms (SNPs) placed in a large scaffold were reported to be associated with the allele for this major gene resistance (Cr1R). Forest restoration efforts often include sugar pine seed derived from the rare resistant individuals (typically Cr1R/Cr1r) identified through an expensive 2-year phenotypic testing program. To validate and geographically characterize the variation in this association and investigate its potential to expedite genetic improvement in forest restoration, we developed a simple PCR-based, diploid genotyping of DNA from needle tissue. By applying this to range-wide samples of susceptible and resistant (Cr1R) trees, we show that the SNPs exhibit a strong, though not complete, association with Cr1R. Paralleling earlier studies of the geographic distribution of Cr1R and the inferred demographic history of sugar pine, the resistance-associated SNPs are marginally more common in southern populations, as is the frequency of Cr1R. Although the strength of the association of the SNPs with Cr1R and thus, their predictive value, also varies with geography, the potential value of this new tool in quickly and efficiently identifying candidate WPBR-resistant seed trees is clear.
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Prost‐Boxoen, Lucas, Quinten Bafort, Antoine Van de Vloet, Fabricio Almeida‐Silva, Yunn Thet Paing, Griet Casteleyn, Sofie D'hondt, Olivier De Clerck e Yves Van de Peer. "Asymmetric genome merging leads to gene expression novelty through nucleo‐cytoplasmic disruptions and transcriptomic shock in Chlamydomonas triploids". New Phytologist, 5 novembre 2024. http://dx.doi.org/10.1111/nph.20249.
Testo completoAbstract (sommario):
Summary Genome merging is a common phenomenon causing a wide range of consequences on phenotype, adaptation, and gene expression, yet its broader implications are not well‐understood. Two consequences of genome merging on gene expression remain particularly poorly understood: dosage effects and evolution of expression. We employed Chlamydomonas reinhardtii as a model to investigate the effects of asymmetric genome merging by crossing a diploid with a haploid strain to create a novel triploid line. Five independent clonal lineages derived from this triploid line were evolved for 425 asexual generations in a laboratory natural selection experiment. Utilizing fitness assays, flow cytometry, and RNA‐Seq, we assessed the immediate consequences of genome merging and subsequent evolution. Our findings reveal substantial alterations in genome size, gene expression, protein homeostasis, and cytonuclear stoichiometry. Gene expression exhibited expression‐level dominance and transgressivity (i.e. expression level higher or lower than either parent). Ongoing expression‐level dominance and a pattern of ‘functional dominance’ from the haploid parent was observed. Despite major genomic and nucleo‐cytoplasmic disruptions, enhanced fitness was detected in the triploid strain. By comparing gene expression across generations, our results indicate that proteostasis restoration is a critical component of rapid adaptation following genome merging in Chlamydomonas reinhardtii and possibly other systems.
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Shahbazi, Mehrdad, Joanna Majka, Denisa Kubíková, Zbigniew Zwierzykowski, Marek Glombik, Jonathan F. Wendel, Joel Sharbrough et al. "Cytonuclear interplay in auto‐ and allopolyploids: a multifaceted perspective from the Festuca‐Lolium complex". Plant Journal, 7 febbraio 2024. http://dx.doi.org/10.1111/tpj.16659.
Testo completoAbstract (sommario):
SUMMARYRestoring cytonuclear stoichiometry is necessary after whole‐genome duplication (WGD) and interspecific/intergeneric hybridization in plants. We investigated this phenomenon in auto‐ and allopolyploids of the Festuca‐Lolium complex providing insights into the mechanisms governing cytonuclear interactions in early polyploid and hybrid generations. Our study examined the main processes potentially involved in restoring the cytonuclear balance after WGD comparing diploids and new and well‐established autopolyploids. We uncovered that both the number of chloroplasts and the number of chloroplast genome copies were significantly higher in the newly established autopolyploids and grew further in more established autopolyploids. The increase in the copy number of the chloroplast genome exceeded the rise in the number of chloroplasts and fully compensated for the doubling of the nuclear genome. In addition, changes in nuclear and organelle gene expression were insignificant. Allopolyploid Festuca × Lolium hybrids displayed potential structural conflicts in parental protein variants within the cytonuclear complexes. While biased maternal allele expression has been observed in numerous hybrids, our results suggest that its role in cytonuclear stabilization in the Festuca × Lolium hybrids is limited. This study provides insights into the restoration of the cytonuclear stoichiometry, yet it emphasizes the need for future research to explore post‐transcriptional regulation and its impact on cytonuclear gene expression stoichiometry. Our findings may enhance the understanding of polyploid plant evolution, with broader implications for the study of cytonuclear interactions in diverse biological contexts.
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Forni, Giobbe, Alexander S. Mikheyev, Andrea Luchetti e Barbara Mantovani. "Gene transcriptional profiles in gonads of Bacillus taxa (Phasmida) with different cytological mechanisms of automictic parthenogenesis". Zoological Letters 8, n. 1 (26 novembre 2022). http://dx.doi.org/10.1186/s40851-022-00197-z.
Testo completoAbstract (sommario):
AbstractThe evolution of automixis – i.e., meiotic parthenogenesis – requires several features, including ploidy restoration after meiosis and maintenance of fertility. Characterizing the relative contribution of novel versus pre-existing genes and the similarities in their expression and sequence evolution is fundamental to understand the evolution of reproductive novelties. Here we identify gonads-biased genes in two Bacillus automictic stick-insects and compare their expression profile and sequence evolution with a bisexual congeneric species. The two parthenogens restore ploidy through different cytological mechanisms: in Bacillus atticus, nuclei derived from the first meiotic division fuse to restore a diploid egg nucleus, while in Bacillus rossius, diploidization occurs in some cells of the haploid blastula through anaphase restitution. Parthenogens’ gonads transcriptional program is found to be largely assembled from genes that were already present before the establishment of automixis. The three species transcriptional profiles largely reflect their phyletic relationships, yet we identify a shared core of genes with gonad-biased patterns of expression in parthenogens which are either male gonads-biased in the sexual species or are not differentially expressed there. At the sequence level, just a handful of gonads-biased genes were inferred to have undergone instances of positive selection exclusively in the parthenogen species. This work is the first to explore the molecular underpinnings of automixis in a comparative framework: it delineates how reproductive novelties can be sustained by genes whose origin precedes the establishment of the novelty itself and shows that different meiotic mechanisms of reproduction can be associated with a shared molecular ground plan.
36
Neale, David B., Aleksey V. Zimin, Amy Meltzer, Akriti Bhattarai, Maurice Amee, Laura Figueroa Corona, Brian J. Allen et al. "A Genome Sequence for the Threatened Whitebark Pine". G3: Genes, Genomes, Genetics, 25 marzo 2024. http://dx.doi.org/10.1093/g3journal/jkae061.
Testo completoAbstract (sommario):
Abstract Whitebark pine (WBP, Pinus albicaulis) is a white pine of subalpine regions in western contiguous US and Canada. WBP has become critically threatened throughout a significant part of its natural range due to mortality from the introduced fungal pathogen white pine blister rust (WPBR, Cronartium ribicola) and additional threats from mountain pine beetle (Dendroctonus ponderosae), wildfire, and maladaptation due to changing climate. Vast acreages of WBP have suffered nearly complete mortality. Genomic technologies can contribute to a faster, more cost-effective approach to the traditional practices of identifying disease-resistant, climate-adapted seed sources for restoration. With deep-coverage Illumina short-reads of haploid megagametophyte tissue and Oxford Nanopore long-reads of diploid needle tissue, followed by a hybrid, multistep assembly approach, we produced a final assembly containing 27.6 Gbp of sequence in 92,740 contigs (N50 537,007 bp) and 34,716 scaffolds (N50 2.0 Gbp). Approximately 87.2% (24.0 Gbp) of total sequence was placed on the twelve WBP chromosomes. Annotation yielded 25,362 protein-coding genes, and over 77% of the genome was characterized as repeats. WBP has demonstrated the greatest variation in resistance to WPBR among the North American white pines. Candidate genes for quantitative resistance include disease resistance genes known as nucleotide-binding leucine-rich-repeat receptors (NLRs). A combination of protein domain alignments and direct genome scanning was employed to fully describe the three subclasses of NLRs. Our high-quality reference sequence and annotation provide a marked improvement in NLR identification compared to previous assessments that leveraged de novo assembled transcriptomes.
37
Patil, D. K., V. K. Gite, V. B. Girnare e A. J. Syed Abubakkar. "Development of CGMS Systems in Pigeonpea with Special Reference to A2 Source of Cytoplasm". LEGUME RESEARCH - AN INTERNATIONAL JOURNAL, Of (27 settembre 2024). http://dx.doi.org/10.18805/lr-5032.
Testo completoAbstract (sommario):
Background: Exploitation of hybrid vigour is quite possible in cross-pollinated crops. However, pigeonpea is a grain legume crop with a moderate level of cross-pollination (20-70%), with diploid (2n = 2×) chromosome number of 22 and genome size of 1C = 858 Mbp. Outcrossing mainly aided by insect pollinators. Commercialization of CMS based hybrid is constrained because of the labor intensiveness of seed production and concerns about seed purity. In pigeonpea, two dominant genes (Rf1 and Rf2) have been identified and reported by Saxena et al., (2011), which impart fertility restoration to the hybrid plants. The fertility restorer (Rf or Fr) genes in the nucleus suppress the male-sterile phenotype and allow the production of high yielding CGMS-based hybrids. Cytoplasmic male-sterile would effectively circumvent these constraints and revolutionize the hybrid seed industry. CGMS based hybrid breeding can be found more reliable to give productive hybrids in pigeonpea but need some expansion. Methods: In the present study, the objective was to develop cytoplasmic-genetic male-sterile (CGMS) lines in pigeonpea through wide hybridization involving conventional backcrossing. Five CGMS lines viz. BDN 2004-1A, BDN 2004-2A, BDN 2004-3A, BDN 2004-4A and BSMR 736A were developed from Cajanus scarabaeoides cytoplasmic background. This paper discusses development of A and B lines by using A2 CMS systems available for pigeonpea. Result: Our investigations on Development of CGMS systems in Pigeonpea with special reference to A2 source of cytoplasm have allowed us to diverse the male sterile lines based on Cajanus scarabaeoides (A2) cytoplasm in pigeonpea which can be used as marker for easy identification, however characterization of these mentioned five CGMS lines will also help in the predicting the performance of progenies in the different breeding programmes.