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1
Badger, Murray R., T. John Andrews, S. M. Whitney, Martha Ludwig, David C. Yellowlees, W. Leggat e G. Dean Price. "The diversity and coevolution of Rubisco, plastids, pyrenoids, and chloroplast-based CO2-concentrating mechanisms in algae". Canadian Journal of Botany 76, n. 6 (1 giugno 1998): 1052–71. http://dx.doi.org/10.1139/b98-074.
Testo completoAbstract (sommario):
Algae have adopted two primary strategies to maximize the performance of Rubisco in photosynthetic CO2 fixation. This has included either the development of a CO2-concentrating mechanism (CCM), based at the level of the chloroplast, or the evolution of the kinetic properties of Rubisco. This review examines the potential diversity of both Rubisco and chloroplast-based CCMs across algal divisions, including both green and nongreen algae, and seeks to highlight recent advances in our understanding of the area and future areas for research. Overall, the available data show that Rubisco enzymes from algae have evolved a higher affinity for CO2 when the algae have adopted a strategy for CO2 fixation that does not utilise a CCM. This appears to be true of both Green and Red Form I Rubisco enzymes found in green and nongreen algae, respectively. However, the Red Form I Rubisco enzymes present in nongreen algae appear to have reduced oxygenase potential at air level of O2. This has resulted in a photosynthetic physiology with a reduced potential to be inhibited by O2 and a reduced need to deal with photorespiration. In the limited number of microalgae that have been examined, there is a strong correlation between the existence of a high-affinity CCM physiology and the presence of pyrenoids in all algae, highlighting the potential importance of these chloroplast Rubisco-containing bodies. However, in macroalgae, there is greater diversity in the apparent relationships between pyrenoids and chloroplast features and the CCM physiology that the species shows. There are many examples of microalgae and macroalgae with variations in the presence and absence of pyrenoids as well as single and multiple chloroplasts per cell. This occurs in both green and nongreen algae and should provide ample material for extending studies in this area. Future research into the function of the pyrenoid and other chloroplast features, such as thylakoids, in the operation of a chloroplast-based CCM needs to be addressed in a diverse range of algal species. This should be approached together with assessment of the coevolution of Rubisco, particularly the evolution of Red Form I Rubisco enzymes, which appear to achieve superior kinetic characteristics when compared with the Rubisco of C3 higher plants, which are derived from green algal ancestors.Key words: Rubisco, CO2-concentrating mechanism, carbonic anhydrase, aquatic photosynthesis, algae, pyrenoids, inorganic carbon.
2
Cui, Jian Sheng, Xiao Hui Xu e Yu Xin Cheng. "Study on the Characteristics of Microcystis aeruginosa Chlorophyll Fluorescence Responding on the Toxicity of HgCl2". Advanced Materials Research 726-731 (agosto 2013): 1538–43. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.1538.
Testo completoAbstract (sommario):
Chlorophyll fluorescence is a quick, precise, non-invasive technique which has been widely used in studies of photosynthesis in micro algae, particularly for investigations of stress physiology of micro algae. The toxicity of heavy metal Hg2+on algaM. aeruginosawas studied by the change in fluorescence intensity ofM. aeruginosaat 435 nm/680 nm which treaded with different Hg2+concentrations for 25 min. The results showed that high concentrations of Hg2+inhibited the photosynthesis ofM. aeruginosa, while a low concentration (0.0005 mg/L) of Hg2+promoted photosynthesis. When Hg2+level range from 0.001 mg/L to 0.500 mg/L, it had significant inhibition effects on photosynthesis ofM. aeruginosa. The chlorophyll fluorescence intensity increased with the concentration of Hg2+(0.001~0.400 mg/L), even the concentration of Hg2+and algal photosynthetic signal had a significant positive correlation, r=0.983 3.
3
Muñoz, Jorge, Juan M. Cancino e MarÍa X. Molina. "Effect of Encrusting Bryozoans on the Physiology of Their Algal Substratum". Journal of the Marine Biological Association of the United Kingdom 71, n. 4 (novembre 1991): 877–82. http://dx.doi.org/10.1017/s0025315400053522.
Testo completoAbstract (sommario):
Traditionally, colonies of encrusting epiphytic bryozoans have been regarded as biotic factors reducing photosynthetic performance in benthic algae. In this study we determined under laboratory conditions the effects of Membranipora tuberculata on the photosynthetic efficiency of the rhodophyte Gelidium rex.Encrusting bryozoans reduce to 44% the incident light reaching the algal thallus. However, concentrations of chlorophyll a and other accessory pigments are significantly higher in encrusted than in non-encrusted thalli. Consequently, photosynthetic efficiency is almost identical in both types of thalli. Although non-encrusted thalli showed a higher photosynthetic V due to higher levels of light reaching the algae, encrusted thalli exhibited a compensatory effect at low photon flux density and reached a similar P value. The detrimental effect of M. tuberculata on photosynthesis could be partially compensated by CO released from bryozoan cells, as G. rex preferred CO over HCO3 as a source of photosynthetic inorganic carbon. These results suggest that physiological interaction between bryozoans and algae, involving the interchange of metabolic substances, are likely to be important.
4
Maruyama, Shumpei, Julia R. Unsworth, Valeri Sawiccy e Virginia M. Weis. "Algae from Aiptasia egesta are robust representations of Symbiodiniaceae in the free-living state". PeerJ 10 (29 luglio 2022): e13796. http://dx.doi.org/10.7717/peerj.13796.
Testo completoAbstract (sommario):
Many cnidarians rely on their dinoflagellate partners from the family Symbiodiniaceae for their ecological success. Symbiotic species of Symbiodiniaceae have two distinct life stages: inside the host, in hospite, and outside the host, ex hospite. Several aspects of cnidarian-algal symbiosis can be understood by comparing these two life stages. Most commonly, algae in culture are used in comparative studies to represent the ex hospite life stage, however, nutrition becomes a confounding variable for this comparison because algal culture media is nutrient rich, while algae in hospite are sampled from hosts maintained in oligotrophic seawater. In contrast to cultured algae, expelled algae may be a more robust representation of the ex hospite state, as the host and expelled algae are in the same seawater environment, removing differences in culture media as a confounding variable. Here, we studied the physiology of algae released from the sea anemone Exaiptasia diaphana (commonly called Aiptasia), a model system for the study of coral-algal symbiosis. In Aiptasia, algae are released in distinct pellets, referred to as egesta, and we explored its potential as an experimental system to represent Symbiodiniaceae in the ex hospite state. Observation under confocal and differential interference contrast microscopy revealed that egesta contained discharged nematocysts, host tissue, and were populated by a diversity of microbes, including protists and cyanobacteria. Further experiments revealed that egesta were released at night. In addition, algae in egesta had a higher mitotic index than algae in hospite, were photosynthetically viable for at least 48 hrs after expulsion, and could competently establish symbiosis with aposymbiotic Aiptasia. We then studied the gene expression of nutrient-related genes and studied their expression using qPCR. From the genes tested, we found that algae from egesta closely mirrored gene expression profiles of algae in hospite and were dissimilar to those of cultured algae, suggesting that algae from egesta are in a nutritional environment that is similar to their in hospite counterparts. Altogether, evidence is provided that algae from Aiptasia egesta are a robust representation of Symbiodiniaceae in the ex hospite state and their use in experiments can improve our understanding of cnidarian-algal symbiosis.
5
Smith, Val H. "Light and Nutrient Effects on the Relative Biomass of Blue-Green Algae in Lake Phytoplankton". Canadian Journal of Fisheries and Aquatic Sciences 43, n. 1 (1 gennaio 1986): 148–53. http://dx.doi.org/10.1139/f86-016.
Testo completoAbstract (sommario):
The factors determining the relative biomass of blue-green algae during the growing season were studied using data from 22 lakes worldwide. Multiple linear regression analyses suggest that total nitrogen (TN), total phosphorus (TP), and light (as estimated from Secchi disc transparency and the depth of the mixed layer) interact to determine the relative biomass of planktonic blue-green algae. At a fixed TN: TP ratio, blue-green relative biomass increases as light availability decreases. At a fixed light level, blue-green relative biomass also increases as the TN: TP ratio decreases. Both effects are consistent with current knowledge of algal physiology, and with a recently proposed theoretical framework for algal community structure.
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Yang, Hui, Baptiste Genot, Solange Duhamel, Ryan Kerney e John A. Burns. "Organismal and cellular interactions in vertebrate–alga symbioses". Biochemical Society Transactions 50, n. 1 (28 febbraio 2022): 609–20. http://dx.doi.org/10.1042/bst20210153.
Testo completoAbstract (sommario):
Photosymbioses, intimate interactions between photosynthetic algal symbionts and heterotrophic hosts, are well known in invertebrate and protist systems. Vertebrate animals are an exception where photosynthetic microorganisms are not often considered part of the normal vertebrate microbiome, with a few exceptions in amphibian eggs. Here, we review the breadth of vertebrate diversity and explore where algae have taken hold in vertebrate fur, on vertebrate surfaces, in vertebrate tissues, and within vertebrate cells. We find that algae have myriad partnerships with vertebrate animals, from fishes to mammals, and that those symbioses range from apparent mutualisms to commensalisms to parasitisms. The exception in vertebrates, compared with other groups of eukaryotes, is that intracellular mutualisms and commensalisms with algae or other microbes are notably rare. We currently have no clear cell-in-cell (endosymbiotic) examples of a trophic mutualism in any vertebrate, while there is a broad diversity of such interactions in invertebrate animals and protists. This functional divergence in vertebrate symbioses may be related to vertebrate physiology or a byproduct of our adaptive immune system. Overall, we see that diverse algae are part of the vertebrate microbiome, broadly, with numerous symbiotic interactions occurring across all vertebrate and many algal clades. These interactions are being studied for their ecological, organismal, and cellular implications. This synthesis of vertebrate–algal associations may prove useful for the development of novel therapeutics: pairing algae with medical devices, tissue cultures, and artificial ecto- and endosymbioses.
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Buschmann, Henrik. "Into another dimension: how streptophyte algae gained morphological complexity". Journal of Experimental Botany 71, n. 11 (9 aprile 2020): 3279–86. http://dx.doi.org/10.1093/jxb/eraa181.
Testo completoAbstract (sommario):
Abstract Land plants with elaborated three-dimensional (3D) body plans have evolved from streptophyte algae. The streptophyte algae are known to exhibit varying degrees of morphological complexity, ranging from single-celled flagellates to branched macrophytic forms exhibiting tissue-like organization. In this review, I discuss mechanisms by which, during evolution, filamentous algae may have gained 2D and eventually 3D body plans. There are, in principle, two mechanisms by which an additional dimension may be added to an existing algal filament or cell layer: first, by tip growth-mediated branching. An example of this mechanism is the emergence and polar expansion of root hairs from land plants. The second possibility is the rotation of the cell division plane. In this case, the plane of the forthcoming cell division is rotated within the parental cell wall. This type of mechanism corresponds to the formative cell division seen in meristems of land plants. This literature review shows that of the extant streptophyte algae, the Charophyceae and Coleochaetophyceae are capable of performing both mechanisms, while the Zygnematophyceae (the actual sister to land plants) show tip growth-based branching only. I finally discuss how apical cells with two or three cutting faces, as found in mosses, may have evolved from algal ancestors.
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Broady, Paul A. "Algae and extreme environments. Ecology and physiology." Phycologia 42, n. 3 (maggio 2003): 317–18. http://dx.doi.org/10.2216/i0031-8884-42-3-317.1.
Testo completo
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Lawrence, Janice E., Corina P. D. Brussaard e Curtis A. Suttle. "Virus-Specific Responses of Heterosigma akashiwo to Infection". Applied and Environmental Microbiology 72, n. 12 (13 ottobre 2006): 7829–34. http://dx.doi.org/10.1128/aem.01207-06.
Testo completoAbstract (sommario):
ABSTRACT We used flow cytometry to examine the process of cell death in the bloom-forming alga Heterosigma akashiwo during infection by a double-stranded DNA virus (OIs1) and a single-stranded RNA virus (H. akashiwo RNA virus [HaRNAV]). These viruses were isolated from the same geographic area and infect the same strain of H. akashiwo. By use of the live/dead stains fluorescein diacetate and SYTOX green as indicators of cellular physiology, cells infected with OIs1 showed signs of infection earlier than HaRNAV-infected cultures (6 to 17 h versus 23 to 29 h). Intracellular esterase activity was lost prior to increased membrane permeability during infection with OIs1, while the opposite was seen with HaRNAV-infected cultures. In addition, OIs1-infected cells accumulated in the cultures while HaRNAV-infected cells rapidly disintegrated. Progeny OIs1 viruses consisted of large and small morphotypes with estimated latent periods of 11 and 17 h, respectively, and about 1,100 and 16,000 viruses produced per cell, respectively. In contrast, HaRNAV produced about 21,000 viruses per cell and had a latent period of 29 h. This study reveals that the characteristics of viral infection in algae are virus dependent and therefore are variable among viruses infecting the same species. This is an important consideration for ecosystem modeling exercises; calculations based on in situ measurements of algal physiology must be sensitive to the diverse responses of algae to viral infection.
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Davy, Simon K., Donelle A. Trautman, Michael A. Borowitzka e Rosalind Hinde. "Ammonium excretion by a symbiotic sponge supplies the nitrogen requirements of its rhodophyte partner". Journal of Experimental Biology 205, n. 22 (15 novembre 2002): 3505–11. http://dx.doi.org/10.1242/jeb.205.22.3505.
Testo completoAbstract (sommario):
SUMMARY Symbioses between sponges and algae are abundant in the nutrient-poor waters of tropical reefs, yet very little is known of the nutritional interactions that may promote this abundance. We measured nitrogen flux between the sponge Haliclona cymiformis and its symbiotic partner,the rhodophyte Ceratodictyon spongiosum, and assessed the potential importance of this flux to the symbiosis. While the association can take up dissolved inorganic nitrogen (DIN) as ammonium and nitrate from the surrounding sea water, enrichment of the water with nitrate did not affect its rates of photosynthesis and respiration. Much of the DIN normally assimilated by the alga is waste ammonium excreted by the sponge. A nitrogen budget for the symbiosis shows that the nitrogen required for algal growth can potentially be provided by sponge catabolism alone, but that only a small amount of nitrogen is available for translocation back to the sponge in organic compounds. The stable isotope composition (δ15N) was consistent with our interpretation of the sponge supplying excretory DIN to its algal partner, while the results also suggested that this DIN limits nitrogen deficiency in the alga. If our observations are typical of sponge—alga symbioses, then the supply of excretory nitrogen could be a major reason why so many algae form symbioses with sponges on coral reefs.
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Caisová, Lenka. "Draparnaldia: a chlorophyte model for comparative analyses of plant terrestrialization". Journal of Experimental Botany 71, n. 11 (26 febbraio 2020): 3305–13. http://dx.doi.org/10.1093/jxb/eraa102.
Testo completoAbstract (sommario):
Abstract It is generally accepted that land plants evolved from streptophyte algae. However, there are also many chlorophytes (a sister group of streptophyte algae and land plants) that moved to terrestrial habitats and even resemble mosses. This raises the question of why no land plants evolved from chlorophytes. In order to better understand what enabled streptophyte algae to conquer the land, it is necessary to study the chlorophytes as well. This review will introduce the freshwater filamentous chlorophyte alga Draparnaldia sp. (Chaetophorales, Chlorophyceae) as a model for comparative analyses between these two lineages. It will also focus on current knowledge about the evolution of morphological complexity in chlorophytes versus streptophytes and their respective morphological/behavioural adaptations to semi-terrestrial habitats, and will show why Draparnaldia is needed as a new model system.
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Legrand, E., T. Kutti, EV Gonzalez Casal, SPS Rastrick, S. Andersen e V. Husa. "Reduced physiological performance in a free-living coralline alga induced by salmon faeces deposition". Aquaculture Environment Interactions 13 (17 giugno 2021): 225–36. http://dx.doi.org/10.3354/aei00403.
Testo completoAbstract (sommario):
Maerl beds are formed by the accumulation of free-living coralline algae and have considerable ecological significance due to the high diversity of associated fauna and flora. The rapid expansion of the Atlantic salmon Salmo salar aquaculture industry in Norway may have major impacts on surrounding maerl beds through the release of effluents, including fish faeces. This study is the first to test the effects of salmon faeces and inorganic sediment deposition on the photosynthesis, respiration, calcification and pigment content of the coralline alga Lithothamnion soriferum. In a 6 wk laboratory experiment, inorganic sediment and salmon faeces deposition significantly reduced the amount of light reaching the surface of coralline algae. No impact of inorganic sediment deposition was detected on L. soriferum physiology, while salmon faeces deposition increased respiration rate and reduced net primary production and calcification. The accumulation of salmon faeces stimulates proliferation of bacteria, with adverse consequences on L. soriferum physiology due to the potential release of toxic compounds. Burial by salmon faeces deposition also affects the physiology of coralline algae due to the flocculation of sticky faeces particles, which may limit nutrient and gas exchanges in the vicinity of thalli. Carbon dioxide accumulation in the vicinity of L. soriferum may lead to a decline in pH and alter the calcification process in cell walls. In natural maerl beds, the negative effect of faeces deposition may be exacerbated by longer-term exposure and the presence of other chemicals released by fish farms.
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Barott, Katie L., Alexander A. Venn, Sidney O. Perez, Sylvie Tambutté e Martin Tresguerres. "Coral host cells acidify symbiotic algal microenvironment to promote photosynthesis". Proceedings of the National Academy of Sciences 112, n. 2 (29 dicembre 2014): 607–12. http://dx.doi.org/10.1073/pnas.1413483112.
Testo completoAbstract (sommario):
Symbiotic dinoflagellate algae residing inside coral tissues supply the host with the majority of their energy requirements through the translocation of photosynthetically fixed carbon. The algae, in turn, rely on the host for the supply of inorganic carbon. Carbon must be concentrated as CO2 in order for photosynthesis to proceed, and here we show that the coral host plays an active role in this process. The host-derived symbiosome membrane surrounding the algae abundantly expresses vacuolar H+-ATPase (VHA), which acidifies the symbiosome space down to pH ∼4. Inhibition of VHA results in a significant decrease in average H+ activity in the symbiosome of up to 75% and a significant reduction in O2 production rate, a measure of photosynthetic activity. These results suggest that host VHA is part of a previously unidentified carbon concentrating mechanism for algal photosynthesis and provide mechanistic evidence that coral host cells can actively modulate the physiology of their symbionts.
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Moulin, Solène L. Y., Audrey Beyly-Adriano, Stéphan Cuiné, Stéphanie Blangy, Bertrand Légeret, Magali Floriani, Adrien Burlacot et al. "Fatty acid photodecarboxylase is an ancient photoenzyme that forms hydrocarbons in the thylakoids of algae". Plant Physiology 186, n. 3 (15 aprile 2021): 1455–72. http://dx.doi.org/10.1093/plphys/kiab168.
Testo completoAbstract (sommario):
Abstract Fatty acid photodecarboxylase (FAP) is one of the few enzymes that require light for their catalytic cycle (photoenzymes). FAP was first identified in the microalga Chlorella variabilis NC64A, and belongs to an algae-specific subgroup of the glucose–methanol–choline oxidoreductase family. While the FAP from C. variabilis and its Chlamydomonas reinhardtii homolog CrFAP have demonstrated in vitro activities, their activities and physiological functions have not been studied in vivo. Furthermore, the conservation of FAP activity beyond green microalgae remains hypothetical. Here, using a C. reinhardtii FAP knockout line (fap), we showed that CrFAP is responsible for the formation of 7-heptadecene, the only hydrocarbon of this alga. We further showed that CrFAP was predominantly membrane-associated and that >90% of 7-heptadecene was recovered in the thylakoid fraction. In the fap mutant, photosynthetic activity was not affected under standard growth conditions, but was reduced after cold acclimation when light intensity varied. A phylogenetic analysis that included sequences from Tara Ocean identified almost 200 putative FAPs and indicated that FAP was acquired early after primary endosymbiosis. Within Bikonta, FAP was retained in secondary photosynthetic endosymbiosis lineages but absent from those that lost the plastid. Characterization of recombinant FAPs from various algal genera (Nannochloropsis, Ectocarpus, Galdieria, Chondrus) provided experimental evidence that FAP photochemical activity was present in red and brown algae, and was not limited to unicellular species. These results thus indicate that FAP was conserved during the evolution of most algal lineages where photosynthesis was retained, and suggest that its function is linked to photosynthetic membranes.
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Cota, Glenn F., e Ralph E. H. Smith. "Ecology of bottom ice algae: III. Comparative physiology". Journal of Marine Systems 2, n. 3-4 (agosto 1991): 297–315. http://dx.doi.org/10.1016/0924-7963(91)90038-v.
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Hagedorn, M., V. L. Carter, J. C. Leong e F. W. Kleinhans. "Physiology and cryosensitivity of coral endosymbiotic algae (Symbiodinium)". Cryobiology 60, n. 2 (aprile 2010): 147–58. http://dx.doi.org/10.1016/j.cryobiol.2009.10.005.
Testo completo
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Al-Ghelani, H. M., A. Y. A. AlKindi, S. Amer e Y. K. Al-Akhzami. "Harmful Algal Blooms: Physiology, Behavior, Population Dynamics and Global Impacts- A Review". Sultan Qaboos University Journal for Science [SQUJS] 10 (1 giugno 2005): 1. http://dx.doi.org/10.24200/squjs.vol10iss0pp1-30.
Testo completoAbstract (sommario):
Harmful, toxic algae are now considered as one of the important players in the newly emerging environmental risk factors. The apparent global increase in harmful algal blooms (HABs) is becoming a serious problem in both aquaculture and fisheries populations. Not only has the magnitude and intensity of public health and economic impacts of these blooms increased in recent years, but the number of geographic locations experiencing toxic algal blooms has also increased dramatically. There are two primary factors causing HABs outbreaks. The natural processes such as upwelling and relaxation, and the anthropogenic loading resulting in eutrophication. However, the influence of global climate changes on algal bloom phenomenon cannot be ignored. The problem warrants development of effective strategies for the management and mitigation of HABs. Progress made in the routine coastal monitoring programs, development of methods for detection of algal species and toxins and coastal modeling activities for predicting HABs reflect the international concerns regarding the impacts of HABs. Innovative techniques using molecular probes will hopefully result in development of rapid, reliable screening methods for phycotoxins and the causative organisms.
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Pozdnyakov, Ilya, Olga Matantseva e Sergei Skarlato. "Consensus channelome of dinoflagellates revealed by transcriptomic analysis sheds light on their physiology". Algae 36, n. 4 (15 dicembre 2021): 315–26. http://dx.doi.org/10.4490/algae.2021.36.12.2.
Testo completoAbstract (sommario):
Ion channels are membrane protein complexes mediating passive ion flux across the cell membranes. Every organism has a certain set of ion channels that define its physiology. Dinoflagellates are ecologically important microorganisms characterized by effective physiological adaptability, which backs up their massive proliferations that often result in harmful blooms (red tides). In this study, we used a bioinformatics approach to identify homologs of known ion channels that belong to 36 ion channel families. We demonstrated that the versatility of the dinoflagellate physiology is underpinned by a high diversity of ion channels including homologs of animal and plant proteins, as well as channels unique to protists. The analysis of 27 transcriptomes allowed reconstructing a consensus ion channel repertoire (channelome) of dinoflagellates including the members of 31 ion channel families: inwardly-rectifying potassium channels, two-pore domain potassium channels, voltage-gated potassium channels (Kv), tandem Kv, cyclic nucleotide-binding domain-containing channels (CNBD), tandem CNBD, eukaryotic ionotropic glutamate receptors, large-conductance calcium-activated potassium channels, intermediate/small-conductance calcium-activated potassium channels, eukaryotic single-domain voltage-gated cation channels, transient receptor potential channels, two-pore domain calcium channels, four-domain voltage-gated cation channels, cation and anion Cys-loop receptors, small-conductivity mechanosensitive channels, large-conductivity mechanosensitive channels, voltage-gated proton channels, inositole-1,4,5- trisphosphate receptors, slow anion channels, aluminum-activated malate transporters and quick anion channels, mitochondrial calcium uniporters, voltage-dependent anion channels, vesicular chloride channels, ionotropic purinergic receptors, animal volage-insensitive cation channels, channelrhodopsins, bestrophins, voltage-gated chloride channels H+/Cl- exchangers, plant calcium-permeable mechanosensitive channels, and trimeric intracellular cation channels. Overall, dinoflagellates represent cells able to respond to physical and chemical stimuli utilizing a wide range of Gprotein coupled receptors- and Ca2+-dependent signaling pathways. The applied approach not only shed light on the ion channel set in dinoflagellates, but also provided the information on possible molecular mechanisms underlying vital cellular processes dependent on the ion transport.
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Van, Anh Tu, Veronika Sommer e Karin Glaser. "The Ecophysiological Performance and Traits of Genera within the Stichococcus-like Clade (Trebouxiophyceae) under Matric and Osmotic Stress". Microorganisms 9, n. 9 (26 agosto 2021): 1816. http://dx.doi.org/10.3390/microorganisms9091816.
Testo completoAbstract (sommario):
Changes in water balance are some of the most critical challenges that aeroterrestrial algae face. They have a wide variety of mechanisms to protect against osmotic stress, including, but not limited to, downregulating photosynthesis, the production of compatible solutes, spore and akinete formation, biofilms, as well as triggering structural cellular changes. In comparison, algae living in saline environments must cope with ionic stress, which has similar effects on the physiology as desiccation in addition to sodium and chloride ion toxicity. These environmental challenges define ecological niches for both specialist and generalist algae. One alga known to be aeroterrestrial and euryhaline is Stichococcus bacillaris Nägeli, possessing the ability to withstand both matric and osmotic stresses, which may contribute to wide distribution worldwide. Following taxonomic revision of Stichococcus into seven lineages, we here examined their physiological responses to osmotic and matric stress through a salt growth challenge and desiccation experiment. The results demonstrate that innate compatible solute production capacity under salt stress and desiccation tolerance are independent of one another, and that salt tolerance is more variable than desiccation tolerance in the Stichococcus-like genera. Furthermore, algae within this group likely occupy similar ecological niches, with the exception of Pseudostichococcus.
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Al-Adilah, Hanan, Martin C. Feiters, Lucy J. Carpenter, Puja Kumari, Carl J. Carrano, Dhia Al-Bader e Frithjof C. Küpper. "Halogens in Seaweeds: Biological and Environmental Significance". Phycology 2, n. 1 (18 febbraio 2022): 132–71. http://dx.doi.org/10.3390/phycology2010009.
Testo completoAbstract (sommario):
Many marine algae are strong accumulators of halogens. Commercial iodine production started by burning seaweeds in the 19th century. The high iodine content of certain seaweeds has potential pharmaceutical and nutritional applications. While the metabolism of iodine in brown algae is linked to oxidative metabolism, with iodide serving the function of an inorganic antioxidant protecting the cell and thallus surface against reactive oxygen species with implications for atmospheric and marine chemistry, rather little is known about the regulation and homoeostasis of other halogens in seaweeds in general and the ecological and biological role of marine algal halogenated metabolites (except for organohalogen secondary metabolites). The present review covers these areas, including the significance of seaweed-derived halogens and of halogens in general in the context of human diet and physiology. Furthermore, the understanding of interactions between halogenated compound production by algae and the environment, including anthropogenic impacts, effects on the ozone layer and global climate change, is reviewed together with the production of halogenated natural products by seaweeds and the potential of seaweeds as bioindicators for halogen radionuclides.
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Wang, J., e AE Douglas. "Nitrogen recycling or nitrogen conservation in an alga-invertebrate symbiosis?" Journal of Experimental Biology 201, n. 16 (15 agosto 1998): 2445–53. http://dx.doi.org/10.1242/jeb.201.16.2445.
Testo completoAbstract (sommario):
When corals and allied animals are deprived of their symbiotic algae, the ammonium content in their tissues rises. This is commonly interpreted as evidence for nitrogen recycling (i.e. algal assimilation of animal waste ammonium into amino acids that are released back to the animal), but it can also be explained as nitrogen conservation by the animal (i.e. reduced net ammonium production in response to the receipt of algal photosynthetic carbon). This study discriminated between these interpretations in two ways. First, the increased ammonium concentration in the sea anemone Aiptasia pulchella, caused by darkness or depletion of the alga Symbiodinium, was partially or completely reversed by supplementing the medium with organic carbon compounds (e.g. <IMG src="/images/symbols/&agr ;.gif" WIDTH="9" HEIGHT="12" ALIGN= "BOTTOM" NATURALSIZEFLAG="3">-ketoglutarate). Second, the activity of the ammonium-assimilating enzyme glutamine synthetase and the concentration of protein amino acids in the free amino acid pool of the animal, which were depressed by darkness and algal depletion, were restored by exogenous carbon compounds. It is concluded that organic carbon, whether derived from algal photosynthate or exogenously, promotes the animal's capacity for ammonium assimilation and reduces ammonium production from amino acid degradation. These processes contribute to nitrogen conservation in the animal, but they confound the interpretation of various studies on nitrogen recycling by symbiotic algae.
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Kateriya, Suneel, Georg Nagel, Ernst Bamberg e Peter Hegemann. "“Vision” in Single-Celled Algae". Physiology 19, n. 3 (giugno 2004): 133–37. http://dx.doi.org/10.1152/nips.01517.2004.
Testo completoAbstract (sommario):
Photosynthetic unicellular algae have a unique visual system. In Chlamydomonas reinhardtii, the pigmented eye comprises the optical system and at least five different rhodopsin photoreceptors. Two of them, the channelrhodopsins, are rhodopsin-ion channel hybrids switched between closed and open states by photoisomerization of the attached retinal chromophore. They promise to become a useful tool for noninvasive control of membrane potential and intracellular ion concentrations.
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Fürst-Jansen, Janine M. R., Sophie de Vries e Jan de Vries. "Evo-physio: on stress responses and the earliest land plants". Journal of Experimental Botany 71, n. 11 (10 gennaio 2020): 3254–69. http://dx.doi.org/10.1093/jxb/eraa007.
Testo completoAbstract (sommario):
Abstract Embryophytes (land plants) can be found in almost any habitat on the Earth’s surface. All of this ecologically diverse embryophytic flora arose from algae through a singular evolutionary event. Traits that were, by their nature, indispensable for the singular conquest of land by plants were those that are key for overcoming terrestrial stressors. Not surprisingly, the biology of land plant cells is shaped by a core signaling network that connects environmental cues, such as stressors, to the appropriate responses—which, thus, modulate growth and physiology. When did this network emerge? Was it already present when plant terrestrialization was in its infancy? A comparative approach between land plants and their algal relatives, the streptophyte algae, allows us to tackle such questions and resolve parts of the biology of the earliest land plants. Exploring the biology of the earliest land plants might shed light on exactly how they overcame the challenges of terrestrialization. Here, we outline the approaches and rationale underlying comparative analyses towards inferring the genetic toolkit for the stress response that aided the earliest land plants in their conquest of land.
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Blaby-Haas, Crysten E., e Sabeeha S. Merchant. "Comparative and Functional Algal Genomics". Annual Review of Plant Biology 70, n. 1 (29 aprile 2019): 605–38. http://dx.doi.org/10.1146/annurev-arplant-050718-095841.
Testo completoAbstract (sommario):
Over 100 whole-genome sequences from algae are published or soon to be published. The rapidly increasing availability of these fundamental resources is changing how we understand one of the most diverse, complex, and understudied groups of photosynthetic eukaryotes. Genome sequences provide a window into the functional potential of individual algae, with phylogenomics and functional genomics as tools for contextualizing and transferring knowledge from reference organisms into less well-characterized systems. Remarkably, over half of the proteins encoded by algal genomes are of unknown function, highlighting the volume of functional capabilities yet to be discovered. In this review, we provide an overview of publicly available algal genomes, their associated protein inventories, and their quality, with a summary of the statuses of protein function understanding and predictions.
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NOVAKOVSKAYA, IRINA V., IRINA N. EGOROVA, NINA V. KULAKOVA, ELENA N. PATOVA, DMITRY M. SHADRIN e OLGA V. ANISSIMOVA. "Morphological and phylogenetic relations of members of the genus Coelastrella (Scenedesmaceae, Chlorophyta) from the Ural and Khentii Mountains (Russia, Mongolia)". Phytotaxa 527, n. 1 (26 novembre 2021): 1–20. http://dx.doi.org/10.11646/phytotaxa.527.1.1.
Testo completoAbstract (sommario):
We describe the morphological features and the phylogenetic relationships of five morphologically similar strains belonging to the genus Coelastrella, which live in different ecological and geographical conditions of terrestrial ecosystems: in the Ural Mountains (Polar, Subpolar, and Northern Urals of Russia) and the Khentii Mountains (Russia and Mongolia). We analysed algal strains stored in the Culture Collection of Algae of the Institute of Biology, Syktyvkar, Russia (SYKOA Ch-045-09, SYKOA Ch-047-11, SYKOA Ch-072-17) and the Culture Collection of Algae at Herbarium of the Siberian Institute of Plant Physiology and Biochemistry, Irkutsk, Russia (IRK-A 2, IRK-A 173). By light microscopy, all samples were assigned to Coelastrella terrestris. However, the phylogenetic analyses based on the nucleotide sequences of 18S rDNA and ITS1-ITS2 showed that only one strain belongs to C. terrestris (IRK-A 173). Other samples were closer to C. oocystiformis (SYKOA Ch-045-09; IRK-A 2) and C. aeroterrestrica (SYKOA Ch-047-11). The strain SYKOA Ch-072-17 is probably a new species for the genus. These results confirmed the high phenotypic variability and the hidden diversity among the members of this green algal group.
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Brown, Matthew B., Matthew S. Edwards e Kwang Young Kim. "Effects of climate change on the physiology of giant kelp, Macrocystis pyrifera, and grazing by purple urchin, Strongylocentrotus purpuratus". ALGAE 29, n. 3 (15 settembre 2014): 203–15. http://dx.doi.org/10.4490/algae.2014.29.3.203.
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Courtecuisse, Emilie, Elias Marchetti, Kevin Oxborough, Peter D. Hunter, Evangelos Spyrakos, Gavin H. Tilstone e Stefan G. H. Simis. "Optimising Multispectral Active Fluorescence to Distinguish the Photosynthetic Variability of Cyanobacteria and Algae". Sensors 23, n. 1 (1 gennaio 2023): 461. http://dx.doi.org/10.3390/s23010461.
Testo completoAbstract (sommario):
This study assesses the ability of a new active fluorometer, the LabSTAF, to diagnostically assess the physiology of freshwater cyanobacteria in a reservoir exhibiting annual blooms. Specifically, we analyse the correlation of relative cyanobacteria abundance with photosynthetic parameters derived from fluorescence light curves (FLCs) obtained using several combinations of excitation wavebands, photosystem II (PSII) excitation spectra and the emission ratio of 730 over 685 nm (Fo(730/685)) using excitation protocols with varying degrees of sensitivity to cyanobacteria and algae. FLCs using blue excitation (B) and green–orange–red (GOR) excitation wavebands capture physiology parameters of algae and cyanobacteria, respectively. The green–orange (GO) protocol, expected to have the best diagnostic properties for cyanobacteria, did not guarantee PSII saturation. PSII excitation spectra showed distinct response from cyanobacteria and algae, depending on spectral optimisation of the light dose. Fo(730/685), obtained using a combination of GOR excitation wavebands, Fo(GOR, 730/685), showed a significant correlation with the relative abundance of cyanobacteria (linear regression, p-value < 0.01, adjusted R2 = 0.42). We recommend using, in parallel, Fo(GOR, 730/685), PSII excitation spectra (appropriately optimised for cyanobacteria versus algae), and physiological parameters derived from the FLCs obtained with GOR and B protocols to assess the physiology of cyanobacteria and to ultimately predict their growth. Higher intensity LEDs (G and O) should be considered to reach PSII saturation to further increase diagnostic sensitivity to the cyanobacteria component of the community.
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Krieger, Erik C., Aleluia Taise, Wendy A. Nelson, Johan Grand, Eric Le Ru, Simon K. Davy e Christopher E. Cornwall. "Tolerance of coralline algae to ocean warming and marine heatwaves". PLOS Climate 2, n. 1 (4 gennaio 2023): e0000092. http://dx.doi.org/10.1371/journal.pclm.0000092.
Testo completoAbstract (sommario):
Ocean warming (OW) and marine heatwaves (MHWs) rapidly transform marine ecosystems, especially when they impact keystone or foundation species. Foundation species such as kelps, fucoids and corals are highly sensitive to heat stress, which threatens the future of temperate seaweed forests and tropical reefs. However, functioning and resilience of these systems also relies on the less conspicuous coralline algae, whose thermal tolerances have gone largely untested. Here, we examined the sensitivity of four temperate coralline algal morphotypes from three different species to four realistic present day and future OW and MHW scenarios (ambient [16°C constant]; ambient+MHW [16°C baseline + a symmetric two-week heatwave with a peak intensity of 18.7°C]; future [18.7°C constant]; future+MHW [18.7°C baseline + a symmetric two-week heatwave with a peak intensity of 21.4°C]). Photo-physiology (e.g., Fv/Fm) and calcification physiology (e.g., proxies for calcifying fluid saturation state ΩCF) were generally unaffected by the treatments, implying a high thermo-tolerance of our study species compared to other important marine foundation species. We ascribe this mainly to their photosynthetic apparatus that, unlike in other photoautotrophs, continued to function under heat stress. Experimental evidence presented here and elsewhere implies that coralline algae are likely to continue to play their crucial ecological roles in a warming ocean. Yet, such predictions are fraught with uncertainty due to the substantial gaps in our knowledge. We attempt to highlight some of these gaps and aim to present potential physiological underpinnings of their thermo-tolerance.
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Dvir, Irit, Reuven Chayoth, Uriel Sod-Moriah, Shraga Shany, Abraham Nyska, Aliza H. Stark, Zecharia Madar e Shoshana Malis Arad. "Soluble polysaccharide and biomass of red microalgaPorphyridiumsp. alter intestinal morphology and reduce serum cholesterol in rats". British Journal of Nutrition 84, n. 4 (ottobre 2000): 469–76. http://dx.doi.org/10.1017/s000711450000177x.
Testo completoAbstract (sommario):
The present study investigated the effects of the red microalgaPorphyridiumsp. on gastrointestinal physiology and lipid metabolism in male Sprague-Dawley rats. Diets containing dietary fibre from pelleted red microalgal cells (biomass) or their sulfated polysaccharide, pectin or cellulose (control) were fed to rats for a period of 30 d. All three fibre-supplemented diets increased the length of both the small intestine and colon, with a significantly greater effect in rats fed the algal polysaccharide. The polysaccharide also increased mucosa and muscularis cross-sectional area of the jejunum, and caused hypertrophy in the muscularis layer. The algal biomass significantly lowered gastrointestinal transit time by 44 % in comparison with the control rats. Serum and mucosal cholecystokinin levels were lower in rats on the pectin and polysaccharide diets, while cholecystokinin levels in rats fed algal biomass were not different from those in the control animals. In comparison with the control diet, all the experimental diets significantly lowered serum cholesterol levels (22–29 %). Feeding of non-fermentable algal polysaccharide or biomass significantly increased faecal weight and bile acid excretion compared with pectin-fed or control rats. The algal polysaccharide and biomass were thus shown to be potent hypocholesterolaemic agents active at low concentrations in the diet. Both metabolic and morphological changes were observed following consumption of algae, suggesting several possible mechanisms by which the alga affects lipid metabolism. The results presented in the present study encourage the use of red microalga as a functional food.
30
CASSELTON, P. J., G. CHANDLER, N. SHAH, G. R. STEWART e N. SUMAR. "GLUTAMINE SYNTHETASE ISOFORMS IN ALGAE". New Phytologist 102, n. 2 (febbraio 1986): 261–70. http://dx.doi.org/10.1111/j.1469-8137.1986.tb00580.x.
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Denny, Mark, e Brian Gaylord. "The mechanics of wave-swept algae". Journal of Experimental Biology 205, n. 10 (15 maggio 2002): 1355–62. http://dx.doi.org/10.1242/jeb.205.10.1355.
Testo completoAbstract (sommario):
SUMMARYWave-swept marine algae must contend with the hydrodynamic forces imposed by extreme water velocities. Nonetheless, they seldom have a shape that appears streamlined and they are constructed of weak, compliant materials. How do they survive? The answer is complex, but a coherent story is beginning to emerge. The combined effect of frond shape and material properties ensures that algae are flexible. In small individuals, flexibility allows the plant to reorient and reconfigure in flow, thereby assuming a streamlined shape and reducing the applied hydrodynamic force. In large individuals, flexibility allows fronds to `go with the flow', a strategy that can at times allow the plant to avoid hydrodynamic forces but may at other times impose inertial loads. Our understanding of algal mechanics is such that we can begin to predict the survivorship of algae as a function of size, spatial distribution and wave climate.
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Zhou, Hong, e Klaus von Schwartzenberg. "Zygnematophyceae: from living algae collections to the establishment of future models". Journal of Experimental Botany 71, n. 11 (19 febbraio 2020): 3296–304. http://dx.doi.org/10.1093/jxb/eraa091.
Testo completoAbstract (sommario):
Abstract The class of conjugating green algae, Zygnematophyceae (Conjugatophyceae), is extremely rich in species and has attracted the interest of phycologists for a long time. It is now widely accepted that this class of charophyte algae holds a key position in the phylogenetic tree of streptophytes, where they represent the closest relatives to all land plants (embryophytes). It is increasingly evident that robust model plants that can be easily cultivated and genetically transformed are necessary to better understand the process of terrestrialization and the related molecular, cellular, and physiological adaptations. Living algae collections play an important role, not only for phylogenomic-based taxonomy but also for screening for suitable model organisms. For this review, we screened six major public algae collections for Zygnematophyceae strains and established a cumulative list comprising 738 different taxa (including species, subspecies, varieties, and forms). From the described biodiversity with 8883 registered taxa (AlgaeBase) the cultured Zygnematophyceae taxa worldwide cover only ~8.3%. We review the past research on this clade of algae and discuss it from the perspective of establishing a model organism. We present data on the life cycle of the genera Micrasterias and Spirogyra, representing the orders Desmidiales and Zygnematales, and outline the current status of genetic transformation of Zygnematophyceae algae and future research perspectives.
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Guolan, Huang, Sun Hongwen e Cong Li Li. "Study on the physiology and degradation of dye with immobilized algae". Artificial Cells, Blood Substitutes, and Biotechnology 28, n. 4 (gennaio 2000): 347–63. http://dx.doi.org/10.3109/10731190009119364.
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Jüttner, F. "Physiology and biochemistry of odorous compounds from freshwater cyanobacteria and algae". Water Science and Technology 31, n. 11 (1 giugno 1995): 69–78. http://dx.doi.org/10.2166/wst.1995.0405.
Testo completoAbstract (sommario):
Freshwater cyanobacteria and algae are responsible for the formation of a wide spectrum of different odorous compounds that are frequently observed in natural waters and are the causes consumer complaints. The physiology and biochemistry of odorous compounds that are permanently in the cells or excreted into the environment are here described, as are the odorous compounds that are generated only after disintegration of the cells and are produced by the initiation of lipoxygenase and carotene oxygenase reactions.
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Zhao, Min, Han Xiao, Dong Sun e Shunshan Duan. "Investigation of the Inhibitory Effects of Mangrove Leaves and Analysis of Their Active Components on Phaeocystis globosa during Different Stages of Leaf Age". International Journal of Environmental Research and Public Health 15, n. 11 (1 novembre 2018): 2434. http://dx.doi.org/10.3390/ijerph15112434.
Testo completoAbstract (sommario):
The presence of harmful algal blooms (HABs) can cause significant problems to the quality of the water, the marine ecosystems, and the human health, and economy worldwide. Biological remediation can inhibit harmful algal growth efficiently in an environmental-friendly manner. Therefore, the research conducted on biological remediation with regard to the inhibition of HABs is becoming a major focus in marine ecology. To date, no study has been reported with regard to the red tides occurring in mangrove wetlands. Therefore, the present study used two mangrove species, namely Bruguiera gymnorrhiza and Kandelia candel and one harmful algae species Phaeocystis globosa as experimental organisms. The present study determined the inhibitory effects and algae physiology of specific aqueous extracts from mangrove leaves on the viability of harmful algae, and analyzed the main chemical composition of the aqueous extracts by ultra-performance liquid chromatography coupled to high resolution mass spectrometry (UPLC-QTOF-MS). The results indicated that the aqueous extracts from different leaf ages of B. gymnorrhiza and K. candel leaves exhibited apparent inhibitory effects on the growth of P. globosa. The inhibitory effects of B. gymnorrhiza and K. candel leaves aqueous extracts on the growth of P. globosa were in the following order: senescent > mature > young leaves. The levels of the parameters superoxide dismutase (SOD) activity, glutathione (GSH), and malondialdehyde (MDA)content in P. globosa following treatment with B. gymnorrhiza and K. candel leaves aqueous extracts were increased as follows: senescent > mature > young leaves. Simultaneously, the intensity of the ion peaks of the specific secondary metabolites assigned 4 (No.: 4 Rt: 2.83 min), 7 (No.: 7 Rt: 3.14 min), 8 (No.: 8 Rt: 3.24 min), 9 (No.: 9 Rt: 3.82min) and 10 (No.: 10 Rt: 4.10 min) were increased. These metabolites were found in the aqueous extracts from B. gymnorrhiza leaves. The intensities of the ion peaks of the secondary metabolites 7, 8 in the aqueous extracts from the K. candel leaves were also increased. The majority of the substances that inhibited the algae found in the mangrove plants were secondary metabolites. Therefore, we considered that the norsesquiterpenes compounds 4, 8, 9, and 10 and a phenolic glycoside compound 7 were the active constituents in the aqueous extracts of the mangrove leaves responsible for the inhibition of algae growth. This evidence provided theoretical guidance for the development of biological methods to control red tides and for the further use of substances with antiproliferative activity against algae.
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Zachleder, V. "Origins of Algae and Their Plastids". Photosynthetica 36, n. 4 (1 gennaio 2000): 600. http://dx.doi.org/10.1023/a:1007020910942.
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Moroney, J. V., S. G. Bartlett e G. Samuelsson. "Carbonic anhydrases in plants and algae". Plant, Cell & Environment 24, n. 2 (febbraio 2001): 141–53. http://dx.doi.org/10.1111/j.1365-3040.2001.00669.x.
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Sansone, Clementina, Christophe Brunet, Douglas M. Noonan e Adriana Albini. "Marine Algal Antioxidants as Potential Vectors for Controlling Viral Diseases". Antioxidants 9, n. 5 (7 maggio 2020): 392. http://dx.doi.org/10.3390/antiox9050392.
Testo completoAbstract (sommario):
As the COVID-19 epidemic expands in the world, and with the previous SARS epidemic, avian flu, Ebola and AIDS serving as a warning, biomedical and biotechnological research has the task to find solutions to counteract viral entry and pathogenesis. A novel approach can come from marine chemodiversity, recognized as a relevant source for developing a future natural “antiviral pharmacy”. Activities of antioxidants against viruses can be exploited to cope with human viral infection, from single individual infections to protection of populations. There is a potentially rich and fruitful reservoir of such compounds thanks to the plethora of bioactive molecules and families present in marine microorganisms. The aim of this communication is to present the state-of-play of what is known on the antiviral activities recognized in (micro)algae, highlighting the different molecules from various algae and their mechanisms of actions, when known. Given the ability of various algal molecules—mainly sulfated polysaccharides—to inhibit viral infection at Stage I (adsorption and invasion of cells), we envisage a need to further investigate the antiviral ability of algae, and their mechanisms of action. Given the advantages of microalgal production compared to other organisms, the opportunity might become reality in a short period of time.
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Lapina, Tatiana, Vladislav Statinov, Roman Puzanskiy e Elena Ermilova. "Arginine-Dependent Nitric Oxide Generation and S-Nitrosation in the Non-Photosynthetic Unicellular Alga Polytomella parva". Antioxidants 11, n. 5 (11 maggio 2022): 949. http://dx.doi.org/10.3390/antiox11050949.
Testo completoAbstract (sommario):
Nitric oxide (NO) acts as a key signaling molecule in higher plants, regulating many physiological processes. Several photosynthetic algae from different lineages are also known to produce NO. However, it remains unclear whether this messenger is produced by non-photosynthetic algae. Among these organisms, the colorless alga Polytomella parva is a special case, as it has lost not only its plastid genome, but also nitrate reductase and nitrite reductase. Up to now, the question of whether NO synthesis occurs in the absence of functional nitrate reductase (NR) and the assimilation of nitrates/nitrites in P. parva has not been elucidated. Using spectrofluorometric assays and confocal microscopy with NO-sensitive fluorescence dye, we demonstrate L-arginine-dependent NO synthesis by P. parva cells. Based on a pharmacological approach, we propose the existence of arginine-dependent NO synthase-like activity in this non-photosynthetic alga. GC-MS analysis provides primary evidence that P. parva synthesizes putrescine, which is not an NO source in this alga. Moreover, the generated NO causes the S-nitrosation of protein cysteine thiol groups. Together, our data argue for NR-independent NO synthesis and its active role in S-nitrosation as an essential post-translational modification in P. parva.
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Cornwall, Christopher E., Steeve Comeau, Hollie Putnam e Verena Schoepf. "Impacts of ocean warming and acidification on calcifying coral reef taxa: mechanisms responsible and adaptive capacity". Emerging Topics in Life Sciences 6, n. 1 (14 febbraio 2022): 1–9. http://dx.doi.org/10.1042/etls20210226.
Testo completoAbstract (sommario):
Ocean warming (OW) and acidification (OA) are two of the greatest global threats to the persistence of coral reefs. Calcifying reef taxa such as corals and coralline algae provide the essential substrate and habitat in tropical reefs but are at particular risk due to their susceptibility to both OW and OA. OW poses the greater threat to future reef growth and function, via its capacity to destabilise the productivity of both taxa, and to cause mass bleaching events and mortality of corals. Marine heatwaves are projected to increase in frequency, intensity, and duration over the coming decades, raising the question of whether coral reefs will be able to persist as functioning ecosystems and in what form. OA should not be overlooked, as its negative impacts on the calcification of reef-building corals and coralline algae will have consequences for global reef accretion. Given that OA can have negative impacts on the reproduction and early life stages of both coralline algae and corals, the interdependence of these taxa may result in negative feedbacks for reef replenishment. However, there is little evidence that OA causes coral bleaching or exacerbates the effects of OW on coral bleaching. Instead, there is some evidence that OA alters the photo-physiology of both taxa. Tropical coralline algal possess shorter generation times than corals, which could enable more rapid evolutionary responses. Future reefs will be dominated by taxa with shorter generation times and high plasticity, or those individuals inherently resistant and resilient to both marine heatwaves and OA.
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Vosolsobě, Stanislav, Roman Skokan e Jan Petrášek. "The evolutionary origins of auxin transport: what we know and what we need to know". Journal of Experimental Botany 71, n. 11 (4 aprile 2020): 3287–95. http://dx.doi.org/10.1093/jxb/eraa169.
Testo completoAbstract (sommario):
Abstract Auxin, represented by indole-3-acetic acid (IAA), has for a long time been studied mainly with respect to the development of land plants, and recent evidence confirms that canonical nuclear auxin signaling is a land plant apomorphy. Increasing sequential and physiological data show that the presence of auxin transport machinery pre-dates the emergence of canonical signaling. In this review, we summarize the present state of knowledge regarding the origins of auxin transport in the green lineage (Viridiplantae), integrating both data from wet lab experiments and sequence evidence on the presence of PIN-FORMED (PIN), PIN-LIKES (PILS), and AUXIN RESISTANT 1/LIKE-AUX1 (AUX1/LAX) homologs. We discuss a high divergence of auxin carrier homologs among algal lineages and emphasize the urgent need for the establishment of good molecular biology models from within the streptophyte green algae. We further postulate and discuss two hypotheses for the ancestral role of auxin in the green lineage. First, auxin was present as a by-product of cell metabolism and the evolution of its transport was stimulated by the need for IAA sequestration and cell detoxification. Second, auxin was primarily a signaling compound, possibly of bacterial origin, and its activity in the pre-plant green algae was a consequence of long-term co-existence with bacteria in shared ecological consortia.
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Teoh, Ming-Li, Wan-Loy Chu e Siew-Moi Phang. "Effect of temperature change on physiology and biochemistry of algae: a review". Malaysian Journal of Science 29, n. 2 (26 agosto 2010): 82–97. http://dx.doi.org/10.22452/mjs.vol29no2.1.
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Kumar, Ajay, Rahul Prasad Singh, Indrajeet Kumar, Priya Yadav, Sandeep Kumar Singh, Kaushalendra, Prashant Kumar Singh et al. "Algal Metabolites Can Be an Immune Booster against COVID-19 Pandemic". Antioxidants 11, n. 3 (24 febbraio 2022): 452. http://dx.doi.org/10.3390/antiox11030452.
Testo completoAbstract (sommario):
The world has faced the challenges of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) for the last two years, first diagnosed at the end of 2019 in Wuhan and widely distributed worldwide. As a result, the WHO has proclaimed the illness brought on by this virus to be a global pandemic. To combat COVID-19, researcher communities continuously develop and implement rapid diagnoses, safe and effective vaccinations and other alternative therapeutic procedures. However, synthetic drug-related side effects and high costs have piqued scientists’ interest in natural product-based therapies and medicines. In this regard, antiviral substances derived from natural resources and some medicines have seen a boom in popularity. For instance, algae are a rich source of compounds such as lectins and sulfated polysaccharides, which have potent antiviral and immunity-boosting properties. Moreover, Algae-derived compounds or metabolites can be used as antibodies and vaccine raw materials against COVID-19. Furthermore, some algal species can boost immunity, reduce viral activity in humans and be recommended for usage as a COVID-19 preventative measure. However, this field of study is still in its early stages of development. Therefore, this review addresses critical characteristics of algal metabolites, their antioxidant potential and therapeutic potential in COVID-19.
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IWATSUKI, KENJI, e YUTAKA NAITOH. "Behavioural Responses to Light in Paramecium Bursaria in Relation to its Symbiotic Green Alga Chlorella". Journal of Experimental Biology 134, n. 1 (1 gennaio 1988): 43–60. http://dx.doi.org/10.1242/jeb.134.1.43.
Testo completoAbstract (sommario):
The behavioural responses to light in the ciliate Paramecium bursaria Focke, which normally contains hundreds of the symbiotic green alga Chlorella in its cytoplasm, were analysed quantitatively to clarify the mechanisms governing photoreception in the cell. P. bursaria was found to possess three kinds of photoreceptor systems for (1) the step-up photophobic response (system I), (2) the step-down photophobic response (system II), and (3) the photokinetic response (system III). Under the influence of light, the symbiotic algae inhibited systems I and III, but activated system II. Thus the cells showed the avoiding reaction when they encountered shade (the step-down photophobic response), and consequently gathered in the light region (photoaccumulation). Inhibition of system I and activation of system II were assumed to be mediated by products of the blue-light effect of the algae, while inhibition of system III was due to photosynthetic products of the algae. The cells whose algae were experimentally removed gathered in the shade (photodispersal) due to the avoiding reaction exhibited by them when they encountered a lighted region (the step-up photophobic response mediated by system I). Lowered swimming velocity and increased frequency of spontaneous changes in the swimming direction in the shade (photokinetic responses mediated by system III) also caused photodispersal.
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Young, Erica B., Lindsay Reed e John A. Berges. "Growth parameters and responses of green algae across a gradient of phototrophic, mixotrophic and heterotrophic conditions". PeerJ 10 (21 luglio 2022): e13776. http://dx.doi.org/10.7717/peerj.13776.
Testo completoAbstract (sommario):
Many studies have shown that algal growth is enhanced by organic carbon and algal mixotrophy is relevant for physiology and commercial cultivation. Most studies have tested only a single organic carbon concentration and report different growth parameters which hampers comparisons and improvements to algal cultivation methodology. This study compared growth of green algae Chlorella vulgaris and Chlamydomonas reinhardtii across a gradient of photoautotrophic-mixotrophic-heterotrophic culture conditions, with five acetate concentrations. Culture growth rates and biomass achieved were compared using different methods of biomass estimation. Both species grew faster and produced the most biomass when supplied with moderate acetate concentrations (1–4 g L−1), but light was required to optimize growth rates, biomass yield, cell size and cell chlorophyll content. Higher acetate concentration (10 g L−1) inhibited algal production. The choice of growth parameter and method to estimate biomass (optical density (OD), chlorophyll a fluorescence, flow cytometry, cell counts) affected apparent responses to organic carbon, but use of OD at 600, 680 or 750 nm was consistent. There were apparent trade-offs among exponential growth rate, maximum biomass, and culture time spent in exponential phase. Different cell responses over 1–10 g L−1 acetate highlight profound physiological acclimation across a gradient of mixotrophy. In both species, cell size vs cell chlorophyll relationships were more constrained in photoautotrophic and heterotrophic cultures, but under mixotrophy, and outside exponential growth phase, these relationships were more variable. This study provides insights into algal physiological responses to mixotrophy but also has practical implications for choosing parameters for monitoring commercial algal cultivation.
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Raven, J. A. "Iron acquisition and allocation in stramenopile algae". Journal of Experimental Botany 64, n. 8 (1 maggio 2013): 2119–27. http://dx.doi.org/10.1093/jxb/ert121.
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CLODE, PETA L., MARTIN SAUNDERS, GARTH MAKER, MARTHA LUDWIG e CRAIG A. ATKINS. "Uric acid deposits in symbiotic marine algae". Plant, Cell & Environment 32, n. 2 (febbraio 2009): 170–77. http://dx.doi.org/10.1111/j.1365-3040.2008.01909.x.
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Buschmann, Henrik, e Andreas Holzinger. "Understanding the algae to land plant transition". Journal of Experimental Botany 71, n. 11 (11 giugno 2020): 3241–46. http://dx.doi.org/10.1093/jxb/eraa196.
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Barrero-Gil, Javier, Blanca Garciadeblás e Begoña Benito. "Sodium, Potassium-ATPases in Algae and Oomycetes". Journal of Bioenergetics and Biomembranes 37, n. 4 (agosto 2005): 269–78. http://dx.doi.org/10.1007/s10863-005-6637-x.
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Barros, Marcelo P., Ernani Pinto, Teresa CS Sigaud-Kutner, Karina HM Cardozo e Pio Colepicolo. "Rhythmicity and oxidative/nitrosative stress in algae". Biological Rhythm Research 36, n. 1-2 (febbraio 2005): 67–82. http://dx.doi.org/10.1080/09291010400028666.
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