The Enigmatic Snow Microorganism, Chionaster nivalis, Is Closely Related to Bartheletia paradoxa (Agaricomycotina, Basidiomycota).
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ABSTRACT:
SUBMITTER: Matsuzaki R
PROVIDER: S-EPMC8209449 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:With the change to one scientific name for fungal taxa, generic names typified by species with sexual or asexual morph types are being evaluated to determine which names represent the same genus and thus compete for use. In this paper generic names of the Agaricomycotina (Basidiomycota) were evaluated to determine synonymy based on their type. Forty-seven sets of sexually and asexually typified names were determined to be congeneric and recommendations are made for which generic name to use. In most cases the principle of priority is followed. However, 16 generic names are recommended for use that do not have priority and thus need to be protected: Aleurocystis over Matula; Armillaria over Acurtis and Rhizomorpha; Asterophora over Ugola; Botryobasidium over Acladium, Allescheriella, Alysidium, Haplotrichum, Physospora, and Sporocephalium; Coprinellus over Ozonium; Coprinopsis over Rhacophyllus; Dendrocollybia over Sclerostilbum and Tilachlidiopsis; Diacanthodes over Bornetina; Echinoporia over Echinodia; Neolentinus over Digitellus; Postia over Ptychogaster; Riopa over Sporotrichum; Scytinostroma over Artocreas, Michenera, and Stereofomes; Tulasnella over Hormomyces; Typhula over Sclerotium; and Wolfiporia over Gemmularia and Pachyma. Nine species names are proposed for protection: Botryobasidium aureum, B. conspersum, B. croceum, B. simile, Pellicularia lembosporum (syn. B. lembosporum), Phanerochaete chrysosporium, Polyporus metamorphosus (syn. Riopa metamorphosa), Polyporus mylittae (syn. Laccocephalum mylittae), and Polyporus ptychogaster (syn. Postia ptychogaster). Two families are proposed for protection: Psathyrellaceae and Typhulaceae. Three new species names and 30 new combinations are established, and one lectotype is designated.
| S-EPMC8359032 | biostudies-literature
Project description:Sexual reproduction in fungi relies on proteins with well-known functions encoded by the mating type (MAT) loci. In the Basidiomycota, MAT loci are often bipartite, with the P/R locus encoding pheromone precursors and pheromone receptors and the HD locus encoding heterodimerizing homeodomain transcription factors (Hd1/Hd2). The interplay between different alleles of these genes within a single species usually generates at least two compatible mating types. However, a minority of species are homothallic, reproducing sexually without an obligate need for a compatible partner. Here, we examine the organization and function of the MAT loci of Cystofilobasidium capitatum, a species in the order Cystofilobasidiales, which is unusually rich in homothallic species. We determined MAT gene content and organization in C. capitatum and found that it resembles a mating type of the closely related heterothallic species Cystofilobasidium ferigula To explain the homothallic sexual reproduction observed in C. capitatum, we examined HD protein interactions in the two Cystofilobasidium species and determined C. capitatum MAT gene expression both in a natural setting and upon heterologous expression in Phaffia rhodozyma, a homothallic species belonging to a clade sister to that of Cystofilobasidium. We conclude that the molecular basis for homothallism in C. capitatum appears to be distinct from that previously established for P. rhodozyma Unlike in the latter species, homothallism in C. capitatum may involve constitutive activation or dispensability of the pheromone receptor and the functional replacement of the usual Hd1/Hd2 heterodimer by an Hd2 homodimer. Overall, our results suggest that homothallism evolved multiple times within the Cystofilobasidiales.IMPORTANCE Sexual reproduction is important for the biology of eukaryotes because it strongly impacts the dynamics of genetic variation. In fungi, although sexual reproduction is usually associated with the fusion between cells belonging to different individuals (heterothallism), sometimes a single individual is capable of completing the sexual cycle alone (homothallism). Homothallic species are unusually common in a fungal lineage named Cystofilobasidiales. Here, we studied the genetic bases of homothallism in one species in this lineage, Cystofilobasidium capitatum, and found it to be different in several aspects from those of another homothallic species, Phaffia rhodozyma, belonging to the genus most closely related to Cystofilobasidium Our results strongly suggest that homothallism evolved independently in Phaffia and Cystofilobasidium, lending support to the idea that transitions between heterothallism and homothallism are not as infrequent as previously thought. Our work also helps to establish the Cystofilobasidiales as a model lineage in which to study these transitions.
| S-EPMC8545103 | biostudies-literature
Project description:Cold environments, such as glaciers and alpine regions, constitute unique habitats for organisms living on Earth. In these harsh ecosystems, snow algae survive, florish, and even become primary producers for microbial communities. How the snow algae maintain physiological activity during violent ambient temperature changes remains unsolved. To explore the cold adaptation mechanisms of the unicellular snow alga Chlamydomonas nivalis, we compared its physiological responses to a model organism from the same genus, Chlamydomonas reinhardtii. When both cell types were exposed to a shift from 22°C to 4°C, C. nivalis exhibited an apparent advantage in cold tolerance over C. reinhardtii, as C. nivalis had both a higher growth rate and photosynthetic efficiency. To determine the cold tolerance mechanisms of C. nivalis, RNA sequencing was used to compare transcriptomes of both species after 1 h of cold treatment, mimicking temperature fluctuations in the polar region. Differential expression analysis showed that C. nivalis had fewer transcriptomic changes and was more stable during rapid temperature decrease relative to C. reinhardtii, especially for the expression of photosynthesis related genes. Additionally, we found that transcription in C. nivalis was precisely regulated by the cold response network, consisting of at least 12 transcription factors and 3 RNA-binding proteins. Moreover, genes participating in nitrogen metabolism, the pentose phosphate pathway, and polysaccharide biosynthesis were upregulated, indicating that increasing resource assimilation and remodeling of metabolisms were critical for cold adaptation in C. nivalis. Furthermore, we identified horizontally transferred genes differentially expressed in C. nivalis, which are critical for cold adaptation in other psychrophiles. Our results reveal that C. nivalis adapts rapid temperature decrease by efficiently regulating transcription of specific genes to optimize resource assimilation and metabolic pathways, providing critical insights into how snow algae survive and propagate in cold environments.
| S-EPMC7874021 | biostudies-literature
Project description:The phylogenetic placement of the monotypic crab plover Dromasardeola (Aves, Charadriiformes) remains controversial. Phylogenetic analysis of anatomical and behavioral traits using phenetic and cladistic methods of tree inference have resulted in conflicting tree topologies, suggesting a close association of Dromas to members of different suborders and lineages within Charadriiformes. Here, we revisited the issue by applying Bayesian and parsimony methods of tree inference to 2,012 anatomical and 5,183 molecular characters to a set of 22 shorebird genera (including Turnix). Our results suggest that Bayesian analysis of anatomical characters does not resolve the phylogenetic relationship of shorebirds with strong statistical support. In contrast, Bayesian and parsimony tree inference from molecular data provided much stronger support for the phylogenetic relationships within shorebirds, and support a sister relationship of Dromas to Glareolidae (pratincoles and coursers), in agreement with previously published DNA-DNA hybridization studies.
| S-EPMC3036115 | biostudies-literature
Project description:Snow and ice present challenging substrates for cellular growth, yet microbial snow communities not only exist, but are diverse and ecologically impactful. These communities are dominated by green algae, but additional organisms, such as fungi, are also abundant and may be important for nutrient cycling, syntrophic interactions, and community structure in general. However, little is known about these non-algal community members, including their taxonomic affiliations. An example of this is Chionaster nivalis, a unicellular fungus that is morphologically enigmatic and frequently observed in snow communities globally. Despite being described over one hundred years ago, the phylogeny and higher-level taxonomic classifications of C. nivalis remain unknown. Here, we isolated and sequenced the internal transcribed spacer (ITS) and the D1-D2 region of the large subunit ribosomal RNA gene of C. nivalis, providing a molecular barcode for future studies. Phylogenetic analyses using the ITS and D1-D2 region revealed that C. nivalis is part of a novel lineage in the class Tremellomycetes (Basidiomycota, Agaricomycotina) for which a new order Chionasterales ord. nov. (MB838717) and family Chionasteraceae fam. nov. (MB838718) are proposed. Comparisons between C. nivalis and sequences generated from environmental surveys revealed that the Chionasterales are globally distributed and probably psychrophilic, as they appear to be limited to the high alpine and arctic regions. These results highlight the unexplored diversity that exists within these extreme habitats and emphasize the utility of single-cell approaches in characterizing these complex algal-dominated communities.
| S-EPMC7990227 | biostudies-literature
Project description:Chloromonas nivalis (Volvocales, Chlorophyceae) is considered a cosmopolitan species of a snow-inhabiting microalga because cysts morphologically identifiable as zygotes of the species are distributed worldwide. However, recent molecular data demonstrated that field-collected cysts identified as the zygotes consist of multiple species. Recently, we demonstrated that species identification of snow-inhabiting Chloromonas species is possible based on light and electron microscopy of asexual life cycles in strains and molecular phylogenetic analyses. Vegetative cells without eyespots and of inverted-teardrop shape have been reported once in North American material of C. nivalis; however, strains with such vegetative cells in snow-inhabiting species of Chloromonas have not been examined taxonomically in detail. Here, we used light and transmission electron microscopy together with molecular analyses of multiple DNA sequences to examine several C. nivalis strains. The morphological data demonstrated that one North American strain could be identified as C. nivalis, whereas three other strains should be re-classified as C. hoshawii sp. nov. and C. remiasii sp. nov. based on vegetative cell morphology, the number of zoospores within the parental cell wall during asexual reproduction, and whether cell aggregates (resulting from repeated divisions of daughter cells retained within a parental cell wall) were observed in the culture. This taxonomic treatment was supported by multigene phylogeny and comparative molecular analyses that included a rapidly evolving DNA region. Our molecular phylogenetic analyses also demonstrated that the North American strain of C. nivalis was phylogenetically separated from the Austrian and Japanese specimens previously identified as C. nivalis based on zygote morphology.
| S-EPMC5865719 | biostudies-literature
Project description:BACKGROUND: In a recent report, the carbohydrate-binding specificities of the plant lectins Galanthus nivalis (GNA) and the closely related lectin from Zea mays (GNAmaize) were determined by glycan array analysis and indicated that GNAmaize recognizes complex-type N-glycans whereas GNA has specificity towards high-mannose-type glycans. Both lectins are tetrameric proteins sharing 64% sequence similarity. RESULTS: GNAmaize appeared to be ~20- to 100-fold less inhibitory than GNA against HIV infection, syncytia formation between persistently HIV-1-infected HuT-78 cells and uninfected CD4+ T-lymphocyte SupT1 cells, HIV-1 capture by DC-SIGN and subsequent transmission of DC-SIGN-captured virions to uninfected CD4+ T-lymphocyte cells. In contrast to GNA, which preferentially selects for virus strains with deleted high-mannose-type glycans on gp120, prolonged exposure of HIV-1 to dose-escalating concentrations of GNAmaize selected for mutant virus strains in which one complex-type glycan of gp120 was deleted. Surface Plasmon Resonance (SPR) analysis revealed that GNA and GNAmaize interact with HIV IIIB gp120 with affinity constants (KD) of 0.33 nM and 34 nM, respectively. Whereas immobilized GNA specifically binds mannose oligomers, GNAmaize selectively binds complex-type GlcNAc?1,2Man oligomers. Also, epitope mapping experiments revealed that GNA and the mannose-specific mAb 2G12 can independently bind from GNAmaize to gp120, whereas GNAmaize cannot efficiently bind to gp120 that contained prebound PHA-E (GlcNAc?1,2man specific) or SNA (NeuAc?2,6X specific). CONCLUSION: The markedly reduced anti-HIV activity of GNAmaize compared to GNA can be explained by the profound shift in glycan recognition and the disappearance of carbohydrate-binding sites in GNAmaize that have high affinity for mannose oligomers. These findings underscore the need for mannose oligomer recognition of therapeutics to be endowed with anti-HIV activity and that mannose, but not complex-type glycan binding of chemotherapeutics to gp120, may result in a pronounced neutralizing activity against the virus.
| S-EPMC3048538 | biostudies-literature
Project description:The alga Chlamydomonas nivalis thrives in polar snow fields and on high-altitude mountain tops, and contributes significantly on primary production in the polar regions, however, the mechanisms underlying this adaptation to low temperatures are unknown. Here, we compared the growth, photosynthetic activity, membrane lipid peroxidation, and antioxidant activity of C. nivalis with those of the model alga C. reinhardtii, under grow temperature and low temperatures. C. nivalis maintained its photosynthetic activity in these conditions by reducing the light-harvesting ability of photosystem II and enhancing the cyclic electron transfer around photosystem I, both of which limited damage to the photosystem from excess light energy and resulted in ATP production, supporting cellular growth and other physiological processes. Furthermore, the increased cyclic electron transfer rate, carotenoid content, and antioxidant enzyme activities jointly regulated the reactive oxygen species levels in C. nivalis, enabling recovery from excess excitation energy and reduced photooxidative damage to the cell. Therefore, we propose a model in which adaptive mechanisms related to photosynthetic regulation promote the survival and even blooming of C. nivalis under polar environment, suggesting that C. nivalis can provide organic carbon sources as an important primary producer for other surrounding life in the polar regions for maintaining ecosystem.
| S-EPMC7297934 | biostudies-literature
Project description:A long-read high-throughput multi-locus sequencing method for fungal systematics and species delimitation
| PRJNA945373 | ENA
Project description:Red snow is a well-known phenomenon caused by microalgae thriving in alpine and polar regions during the melting season. The ecology and biodiversity of these organisms, which are adapted to low temperatures, high irradiance and freeze-thaw events, are still poorly understood. We compared two different snow habitats containing two different green algal genera in the European Alps, namely algae blooming in seasonal rock-based snowfields (Chlamydomonas nivalis) and algae dominating waterlogged snow bedded over ice (Chlainomonassp.). Despite the morphological similarity of the red spores found at the snow surface, we found differences in intracellular organization investigated by light and transmission electron microscopy and in secondary pigments investigated by chromatographic analysis in combination with mass spectrometry. Spores ofChlainomonassp. show clear differences fromChlamydomonas nivalisin cell wall arrangement and plastid organization. Active photosynthesis at ambient temperatures indicates a high physiological activity, despite no cell division being present. Lipid bodies containing the carotenoid astaxanthin, which produces the red color, dominate cells of both species, but are modified differently. While inChlainomonassp. astaxanthin is mainly esterified with two fatty acids and is more apolar, inChamydomonas nivalis, in contrast, less apolar monoesters prevail.
| S-EPMC4815433 | biostudies-literature