Frontiers in Protistology最新文献

{"title":"Nuclear genomes of dinoflagellates reveal evolutionarily conserved pattern of RNA editing relative to stress response","authors":"Yibi Chen, K. Dougan, Debashish Bhattacharya, C. Chan","doi":"10.3389/frpro.2024.1320917","DOIUrl":"https://doi.org/10.3389/frpro.2024.1320917","url":null,"abstract":"Dinoflagellates are a group of diverse protists with complex genomes whose gene expression regulation mechanisms remain little known. RNA editing is a post-transcriptional regulatory mechanism of gene expression utilized by diverse species, and has been described primarily in the plastid and mitochondrial genomes of dinoflagellates. Its role in post-transcriptional regulation in the nuclear genomes of dinoflagellates remains largely unexplored. Here, integrating genome and transcriptome data from two dinoflagellate taxa in a comparative analysis, we identified 10,486 and 69,953 putative RNA editing sites in the nuclear genomes of the coral symbiont, Durusdinium trenchii CCMP2556 and the free-living bloom-forming taxon, Prorocentrum cordatum CCMP1329. We recovered all 12 possible types of RNA edits, with more edits representing transitions than transversions. In contrast to other eukaryotes, we found a dominance of A-to-T transversion in non-coding regions, many of which were condition-specific. Overall, the RNA editing sites implicate 7.5% of D. trenchii genes and 13.2% of P. cordatum genes. Some sites (1.5% in D. trenchii and more-substantially 62.3% in P. cordatum) were edited at significantly different frequencies in distinct growth conditions. The distribution of editing types and locations exhibited conserved patterns between the two phylogenetically distant species. Interestingly, A-to-T editing within the untranslated regions appear to be associated with upregulation of the edited genes in response to heat stress. These results lend support to the hypothesis that RNA editing is a key molecular mechanism that underpins regulation of gene expression in dinoflagellates.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":" 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140990527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contaminant or goldmine? In silico assessment of Symbiodiniaceae community using coral hologenomes","authors":"Hisatake Ishida, Cynthia Riginos, Cheong Xin Chan","doi":"10.3389/frpro.2024.1376877","DOIUrl":"https://doi.org/10.3389/frpro.2024.1376877","url":null,"abstract":"Endosymbiotic dinoflagellates of the family Symbiodiniaceae are symbionts essential to corals and other marine organisms. A coral holobiont consists of the coral host, Symbiodiniaceae, and other microbes that together sustain the overall productivity and coral health. Coral hologenome data, generated from all interacting components of a coral holobiont, are key for elucidating the molecular mechanisms that underpin the resilience of the holobiont to changing environments. Although coral hologenome data are often dominated by host coral genomic sequences, they provide an avenue for recovering genomic sequences from Symbiodiniaceae in hospite. Here, we review recent advances in the approaches for assessing community diversity of in hospite Symbiodiniaceae from coral hologenome data. Using a case study based on existing hologenome datasets of the Acropora kenti coral, we highlight how hologenome datasets in large numbers can provide a useful analysis platform for assessing Symbiodiniaceae diversity and their function in coral holobionts.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":"105 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140751869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diversity of lipid profiles of Symbiodiniaceae under temperature and nutrient stress","authors":"Laura M. La Motta, M. Padula, Brigitte Sommer, E. Camp, Jennifer L. Matthews","doi":"10.3389/frpro.2024.1320353","DOIUrl":"https://doi.org/10.3389/frpro.2024.1320353","url":null,"abstract":"Lipid-based survival mechanisms allow microalgae to occupy wide geographical ranges and survive abiotic stress. The protist Symbiodiniaceae are globally distributed from temperate to tropical environments, and establish mutualisms with numerous hosts, including cnidarians. The ability for these dinoflagellates to maintain cellular function under wide ranging environmental conditions will influence the survival and geographic distribution of their hosts. One mechanism that microalgae utilize to adapt to environmental changes is lipid remodeling, such as increased saturation of membranes to maintain the structural integrity under temperature changes, and lipid accumulation when nutrient availability decreases. Whether Symbiodiniaceae utilize lipid remodeling to adapt to sublethal environmental change is yet to be resolved. This study examines the effects of temperature (16°C to 31°C), and nitrogen (N) and phosphorus (P) availability, on the lipid composition and physiology of cultured Symbiodiniaceae (from genera Breviolum, Cladocopium and Durusdinium) isolated from temperate or tropical environments. Glycerolipids, particularly triacyclglycerols, increased while cell size decreased under N- and NP-nutrient limited cultures, across all Symbiodiniaceae species. P-limitation caused a decrease in phosphatidylcholine, an important membrane lipid, and saw an increase in isoprenol lipids. This suggests a diversion of phosphorus from phospholipid membranes to the biosynthesis of membrane-stabilizing isoprenes. Reduced photophysiology under P-limitation in all Symbiodiniaceae further supports evidence that P-limitation induced stress in these Symbiodiniaceae cells. As expected, growth rate was reduced in all Symbiodiniaceae at temperature extremes (31°C). Significant increases in oxidized lipids, particularly oxidized phosphatidylinositol, and a reduction in ether-linked phospholipids in cultures grown at 31°C, suggests increased reactive oxygen species (ROS) abundance in these cells. In addition, at 31 °C, D. trenchii and both C. goreaui spp. cell size increased, a common sign of ROS accumulation, cell cycle arrest and necrosis. The observed increases in lipid energy storage (triacylglycerols and isoprenoids) under nutrient stress, as well as ROS-mitigation via lipid remodeling leading to increases in saturated fatty acids and oxidized lipids under temperatures stress, suggest Symbiodiniaceae can remodel their lipids to adapt to environmental shifts. If similar mechanisms occur in hospite, this could be an adaptive strategy for coral holobionts under a changing climate.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":"70 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140424298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deleterious effects of free fatty acids and hydrogen peroxide towards the dinoflagellate Gymnodinium catenatum","authors":"Martín Fernando Encinas-Yánez, C. Band-Schmidt, Tania Zenteno-Savín, Ignacio Leyva-Valencia, Leyberth José Fernández Herrera, Elena Palacios-Mechetnov","doi":"10.3389/frpro.2024.1302560","DOIUrl":"https://doi.org/10.3389/frpro.2024.1302560","url":null,"abstract":"Allelopathy refers to biochemical interactions among competing microalgae, it involves a donor species that produces metabolites which can cause inhibitory effects on susceptible species. This phenomenon can participate in the regulation of harmful algal blooms. The dinoflagellate Gymnodinium catenatum is negatively affected by allelopathic interactions with co-occurring microalgae species, like Chattonella marina var. marina, which has been suggested to produce reactive oxygen species (ROS) and free fatty acids (FFA) as nocive and allelopathic agents. This study explored the effect of hydrogen peroxide (H2O2) and the main fatty acids produced by C. marina. An analysis of fatty acids content of C. marina in exponential phase detected 16:0 (12.5 ± 0.01%), 18:4ω-3 (15.4 ± 0.36%) and 20:5ω-3 (35.4 ± 0.71%) as the most abundant. These fatty acids along with H2O2 were used in dose-response bioassays with cultures of G. catenatum in exponential phase. Results suggest that these substances affect cell morphology, including the loss of motility and signs of chlorosis, as well as the chain forming qualities of G. catenatum. Toxicity among these substances varied, suggesting that the polyunsaturated fatty acid 18:4ω-3 can potentially act as a more effective allelochemical (LD50 = 1.7 ± 0.19 mg L-1 at 24 h), followed by 20:5ω-3 (LD50 = 3.6 ± 0.17 mg L-1 at 24 h) and the saturated fatty acid 16:0 (LD50 = 6.2 ± 1.05 at 48 h). Our results suggest these substances can act, at least partially, as allelochemicals, with PUFA being the most effective metabolites. These results contribute in elucidating the potential role of ROS and FFA in allelopathy in marine phytoplankton communities.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":"5 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139893462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deleterious effects of free fatty acids and hydrogen peroxide towards the dinoflagellate Gymnodinium catenatum","authors":"Martín Fernando Encinas-Yánez, C. Band-Schmidt, Tania Zenteno-Savín, Ignacio Leyva-Valencia, Leyberth José Fernández Herrera, Elena Palacios-Mechetnov","doi":"10.3389/frpro.2024.1302560","DOIUrl":"https://doi.org/10.3389/frpro.2024.1302560","url":null,"abstract":"Allelopathy refers to biochemical interactions among competing microalgae, it involves a donor species that produces metabolites which can cause inhibitory effects on susceptible species. This phenomenon can participate in the regulation of harmful algal blooms. The dinoflagellate Gymnodinium catenatum is negatively affected by allelopathic interactions with co-occurring microalgae species, like Chattonella marina var. marina, which has been suggested to produce reactive oxygen species (ROS) and free fatty acids (FFA) as nocive and allelopathic agents. This study explored the effect of hydrogen peroxide (H2O2) and the main fatty acids produced by C. marina. An analysis of fatty acids content of C. marina in exponential phase detected 16:0 (12.5 ± 0.01%), 18:4ω-3 (15.4 ± 0.36%) and 20:5ω-3 (35.4 ± 0.71%) as the most abundant. These fatty acids along with H2O2 were used in dose-response bioassays with cultures of G. catenatum in exponential phase. Results suggest that these substances affect cell morphology, including the loss of motility and signs of chlorosis, as well as the chain forming qualities of G. catenatum. Toxicity among these substances varied, suggesting that the polyunsaturated fatty acid 18:4ω-3 can potentially act as a more effective allelochemical (LD50 = 1.7 ± 0.19 mg L-1 at 24 h), followed by 20:5ω-3 (LD50 = 3.6 ± 0.17 mg L-1 at 24 h) and the saturated fatty acid 16:0 (LD50 = 6.2 ± 1.05 at 48 h). Our results suggest these substances can act, at least partially, as allelochemicals, with PUFA being the most effective metabolites. These results contribute in elucidating the potential role of ROS and FFA in allelopathy in marine phytoplankton communities.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":"252 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139896089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular approaches and challenges for monitoring marine harmful algal blooms in a changing world","authors":"Kirsty F. Smith, J. Stuart, Lesley L. Rhodes","doi":"10.3389/frpro.2023.1305634","DOIUrl":"https://doi.org/10.3389/frpro.2023.1305634","url":null,"abstract":"Harmful algal blooms (HABs) of marine microalgae are a growing concern globally and many studies predict that their occurrence, range, and toxicity may increase with climate change, highlighting the need for responsive and adaptable monitoring techniques. Monitoring programmes for HABs require appropriate sampling techniques, accurate and quantitative identification of potentially toxic taxa, and the ability to respond to novel species or HAB events. These challenges have made it difficult to move past traditional techniques, but research tools are continuing to be developed to bring new opportunities for both monitoring programmes and fundamental understanding of these globally significant organisms within a changing landscape.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140506309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracking down the rare ciliate biosphere","authors":"James Weiss, G. Esteban","doi":"10.3389/frpro.2023.1308546","DOIUrl":"https://doi.org/10.3389/frpro.2023.1308546","url":null,"abstract":"In protists, rare species include dormant organisms and those that do not reach high population abundance, and therefore, are not detected in the samples. These rare microorganisms are part of the so-called ‘rare microbial biosphere’. Although some may occasionally become abundant or dominant under particular environmental conditions, others do have a very rare occurrence, characterized by always having very low populations. The rare protist biosphere represents a significant component of microbial communities, and it is crucial for maintaining ecosystem biodiversity and function. In this study, we aim to demonstrate the richness of the rare ciliate biosphere and hypothesize on the reasons of rarity by combining morphological and ecological details on some exceedingly rare ciliates. The study includes the first report of different morphotypes of Dactylochlamys since 1928, first report of Penardiella undulata since 1930, second report of Penardiella interrupta since 1930, and an undescribed Penardiella species. The first report of Bryophyllum caudatum since 1933, microscopical observations and taxonomical discussion of the rare Legendrea bellerophon and of and undescribed Legendrea species. A new Apertospathula sp. with prokaryotic endosymbionts is described. The rarity of these species is explored and explained by their anaerobic metabolism combined with their prey selection.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":"4 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140512640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dinophysis, a highly specialized mixoplanktonic protist","authors":"Beatriz Reguera, María García-Portela, Esther Velasco-Senovilla, P. Rial, Laura Escalera, Patricio A. Díaz, Francisco Rodríguez","doi":"10.3389/frpro.2023.1328026","DOIUrl":"https://doi.org/10.3389/frpro.2023.1328026","url":null,"abstract":"Several Dinophysis species produce lipophilic toxins (diarrhetic shellfish poisoning, DSP and pectenotoxins PTX) which are transferred through the food web. Even at low cell densities (< 103 cell L-1), they can cause human illness and shellfish harvesting bans; toxins released into the water may kill early life stages of marine organisms. Dinophysis species are mixotrophs: they combine phototrophy (by means of kleptoplastids stolen from their prey) with highly selective phagotrophy on the ciliate Mesodinium, also a mixotroph which requires cryptophyte prey of the Teleaulax/Geminigera clade. Life cycle strategies, biological interactions and plastid acquisition and functioning in Dinophysis species make them exemplars of resilient holoplanktonic mixoplankters and of ongoing speciation and plastidial evolution. Nevertheless, 17 years after the first successful culture was established, the difficulties in isolating and establishing cultures with local ciliate prey, the lack of robust molecular markers for species discrimination, and the patchy distribution of low-density populations in thin layers, hinder physiological experiments to obtain biological measurements of their populations and slow down potential advances with next-generation technologies. The Omic’s age in Dinophysis research has only just started, but increased efforts need to be invested in systematic studies of plastidic diversity and culture establishment of ciliate and cryptophyte co-occurring with Dinophysis in the same planktonic assemblages.","PeriodicalId":516940,"journal":{"name":"Frontiers in Protistology","volume":"11 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140512346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}