K.V. Mikhailov’s research while affiliated with The Institute for Information Transmission Problems, Russian Academy of Sciences and other places

Fungi are one of the most diverse groups of organisms with an estimated number of species in the range of 2–3 million. The higher-level ranking of fungi has been discussed in the framework of molecular phylogenetics since Hibbett et al., and the definition and the higher ranks (e.g., phyla) of the ‘true fungi’ have been revised in several subsequent publications. Rapid accumulation of novel genomic data and the advancements in phylogenetics now facilitate a robust and precise foundation for the higher-level classification within the kingdom. This study provides an updated classification of the kingdom Fungi , drawing upon a comprehensive phylogenomic analysis of Holomycota , with which we outline well-supported nodes of the fungal tree and explore more contentious groupings. We accept 19 phyla of Fungi, viz . Aphelidiomycota , Ascomycota , Basidiobolomycota , Basidiomycota , Blastocladiomycota , Calcarisporiellomycota , Chytridiomycota , Entomophthoromycota , Entorrhizomycota , Glomeromycota , Kickxellomycota , Monoblepharomycota , Mortierellomycota , Mucoromycota , Neocallimastigomycota , Olpidiomycota , Rozellomycota , Sanchytriomycota, and Zoopagomycota . In the phylogenies, Caulochytriomycota resides in Chytridiomycota ; thus, the former is regarded as a synonym of the latter, while Caulochytriomycetes is viewed as a class in Chytridiomycota . We provide a description of each phylum followed by its classes. A new subphylum, Sanchytriomycotina Karpov is introduced as the only subphylum in Sanchytriomycota . The subclass Pneumocystomycetidae Kirk et al. in Pneumocystomycetes , Ascomycota is invalid and thus validated. Placements of fossil fungi in phyla and classes are also discussed, providing examples.

Transglutaminases are enzymes that carry out post-translational modifications of proteins and participate in the regulation of their activities. Here, we show for the first time that the transglutaminase genes in the basal metazoan, the sea sponge Halisarca dujardinii, are organized in a cluster, similarly to mammalian transglutaminases. The regulatory regions of six transglutaminase genes and their differential expression in the course of the life cycle of H. dujardinii suggest independent regulation of these genes. The decrease in transglutaminase activities by cystamine facilitates restoration of the multicellular structures of this sponge after its mechanical dissociation. For the first time we observed that this decrease in transglutaminase activities was accompanied by generation of the reactive oxygen species in the cells of a basal metazoan. The study of transglutaminases in the basal metazoans and other sea-dwelling organisms might provide better understanding of the evolution and specific functions of these enzymes in higher animals.

Microtubules are an indispensable component of all eukaryotic cells due to their role in mitotic spindle formation, yet their organization and number can vary greatly in the interphase. The last common ancestor of all eukaryotes already had microtubules and microtubule motor proteins moving along them. Sponges are traditionally regarded as the oldest animal phylum. Their body does not have a clear differentiation into tissues, but it contains several distinguishable cell types. The choanocytes stand out among them and are responsible for creating a flow of water with their flagella and increasing the filtering and feeding efficiency of the sponge. Choanocyte flagella contain microtubules, but thus far, observing a developed system of cytoplasmic microtubules in non-flagellated interphase sponge cells has been mostly unsuccessful. In this work, we combine transcriptomic analysis, immunofluorescence, and electron microscopy with time-lapse recording to demonstrate that microtubules appear in the cytoplasm of sponge cells only when transdifferentiation processes are activated. We conclude that dynamic cytoplasmic microtubules in the cells of sponges are not a persistent but rather a transient structure, associated with cellular plasticity.

The phylum Nematoda remains very poorly sampled for mtDNA, with a strong bias toward parasitic, economically important or model species of the Chromadoria lineage. Most chromadorian mitogenomes share a specific order of genes encoded on one mtDNA strand. However, the few sequenced representatives of the Dorylaimia lineage exhibit a variable order of mtDNA genes encoded on both strands. While the ancestral arrangement of nematode mitogenome remains undefined, no evidence has been reported for Enoplia, the phylum's third early divergent major lineage. We describe the first mitogenome of an enoplian nematode, Campydora demonstrans, and contend that the complete 37-gene repertoire and both-strand gene encoding are ancestral states preserved in Enoplia and Dorylaimia versus the derived mitogenome arrangement in some Chromadoria. The C. demonstrans mitogenome is 17,018 bp in size and contains a noncoding perfect inverted repeat with 2013 bp-long arms, subdividing the mitogenome into two coding regions. This mtDNA arrangement is very rare among animals and instead resembles that of chloroplast genomes in land plants. Our report broadens mtDNA taxonomic sampling of the phylum Nematoda and adds support to the applicability of cox1 gene as a phylogenetic marker for establishing nematode relationships within higher taxa.

The Global Consortium for the Classification of Fungi and fungus-like taxa is an international initiative of more than 550 mycologists to develop an electronic structure for the classification of these organisms. The members of the Consortium originate from 55 countries/regions worldwide, from a wide range of disciplines, and include senior, mid-career and early-career mycologists and plant pathologists. The Consortium will publish a biannual update of the Outline of Fungi and funguslike taxa, to act as an international scheme for other scientists. Notes on all newly published taxa at or above the level of species will be prepared and published online on the Outline of Fungi website (https://www.outlineoffungi.org/), and these will be finally published in the biannual edition of the Outline of Fungi and fungus-like taxa. Comments on recent important taxonomic opinions on controversial topics will be included in the biannual outline. For example, ‘to promote a more stable taxonomy in Fusarium given the divergences over its generic delimitation’, or ‘are there too many genera in the Boletales?’ and even more importantly, ‘what should be done with the tremendously diverse ‘dark fungal taxa?’ There are undeniable differences in mycologists’ perceptions and opinions regarding species classification as well as the establishment of new species. Given the pluralistic nature of fungal taxonomy and its implications for species concepts and the nature of species, this consortium aims to provide a platform to better refine and stabilize fungal classification, taking into consideration views from different parties. In the future, a confidential voting system will be set up to gauge the opinions of all mycologists in the Consortium on important topics. The results of such surveys will be presented to the International Commission on the Taxonomy of Fungi (ICTF) and the Nomenclature Committee for Fungi (NCF) with opinions and percentages of votes for and against. Criticisms based on scientific evidence with regards to nomenclature, classifications, and taxonomic concepts will be welcomed, and any recommendations on specific taxonomic issues will also be encouraged; however, we will encourage professionally and ethically responsible criticisms of others’ work. This biannual ongoing project will provide an outlet for advances in various topics of fungal classification, nomenclature, and taxonomic concepts and lead to a community-agreed classification scheme for the fungi and fungus-like taxa. Interested parties should contact the lead author if they would like to be involved in future outlines.

Delta-aminolevulinic acid dehydratase (ALAD) is a key enzyme in the cytoplasmic pathway of heme biosynthesis. Here, a primary structure of the ALAD gene of the marine cold-water sponge Halisarca dujardinii, a multimeric structure of the ALAD/hemB protein, and the ALAD gene expression during the sponge annual reproductive cycle were analyzed. On the base of results obtained one can suppose that the sponge ALAD gene expression is regulated by the transcription factor GATA-1 and DNA methylation. Re-aggregation of the sponge cells was accompanied by a decrease in ALAD expression and a change in the cellular content of the active ALAD/hemB form. Further study of heme biosynthesis and the role of ALAD/hemB in morphogenesis of basal animals may provide new opportunities for correcting pathologies in higher animals.

Tikhonenkov et al. introduce the Provora-a newly described, yet ancient, supergroup of unicellular protists encompassing as much genetic diversity as animals and fungi combined.

Centrohelids (Haptista: Centroplasthelida) are axopodial protists with a remarkable diversity of external siliceous scale morphologies. It is believed that the last common ancestor of centrohelids had a double layer of siliceous scales composed of plate scales closer to a cell surface and spine scales radiating outwards. The characteristic morphotype of spine scales with a heart-shaped base was once believed to be a unique feature of the genus Choanocystis, as it was defined by Siemensma and Roijackers (1988). Further research revealed that this morphology is present in different and sometimes distantly related lineages: Ozanamiidae, Meringosphaeridae, and Marophryidae. Here, we report the fourth clade, Pterocystidae, which is also revealed to contain representatives having this phenotype. Cernunnos gen. nov. is erected here to place Cernunnos uralica sp. nov., Cernunnos arctica sp. nov., Cernunnos america sp. nov., and Cernunnos antarctica Tikhonenkov et Mylnikov, 2010, Gerasimova comb. nov. C. uralica was studied with scanning electron microscopy and SSU rDNA sequencing. Molecular phylogenetic analysis placed it into marine environmental clade P within Pterocystida. The ubiquity of spine scales with heart-shaped bases could be an example of parallel evolution, but taking into account the considerable similarity it is likely an ancestral trait, acquired from the last common ancestor of centrohelids.

Aminolevulinic acid dehydratase (ALAD) is a key enzyme of the cytoplasmic heme biosynthesis pathway. The primary structure of the ALAD gene, the multimeric structure of the ALAD/hemB protein, and ALAD expression during the annual reproductive cycle were studied in the cold-water marine sponge Halis-arca dujardinii. The results implicated the GATA-1 transcription factor and DNA methylation in regulating ALAD expression. Re-aggregation of sponge cells was accompanied by a decrease in ALAD expression and a change in the cell content of an active ALAD/hemB form. Further study of heme biosynthesis and the role of ALAD/hemB in morphogenesis of basal animals may provide new opportunities for treating pathologies in higher animals.