Graduate Student Conference in Russian Language and Literatures (Helsinki—Tallinn—Tartu)

This is an overview of a newly established series of Estonian-Finnish conferences on Russian language and literatures (russkaia filologiia). In 2023, this conference united graduate students from Croatia, Czechia, Estonia, Finland, Germany, Israel, Italy, Latvia, Poland, Switzerland, the US and Uzbekistan. The first conference of the series took place at Tallinn University from May 12 to 14, 2023, while the upcoming two conferences will be held in Tartu (2024) and Helsinki (2025).KEYWORDS: Tallinn University, Tartu University, University of Helsinki, Conference Overview

A Reference Genome from the Symbiotic Hydrozoan, Hydra viridissima

Various Hydra species have been employed as model organisms since the 18(th) century. Introduction of transgenic and knock-down technologies made them ideal experimental systems for studying cellular and molecular mechanisms involved in regeneration, body-axis formation, senescence, symbiosis, and holobiosis. In order to provide an important reference for genetic studies, the Hydra magnipapillata genome (species name has been changed to H. vulgaris) was sequenced a decade ago (Chapman et al., 2010) and the updated genome assembly, Hydra 2.0, was made available by the National Human Genome Research Institute in 2017. While H. vulgaris belongs to the non-symbiotic brown hydra lineage, the green hydra, Hydra viridissima, harbors algal symbionts and belongs to an early diverging clade that separated from the common ancestor of brown and green hydra lineages at least 100 million years ago (Schwentner and Bosch 2015; Khalturin et al., 2019). While interspecific interactions between H. viridissima and endosymbiotic unicellular green algae of the genus Chlorella have been a subject of interest for decades, genomic information about green hydras was nonexistent. Here we report a draft 280-Mbp genome assembly for Hydra viridissima strain A99, with a scaffold N50 of 1.1 Mbp. The H. viridissima genome contains an estimated 21,476 protein-coding genes. Comparative analysis of Pfam domains and orthologous proteins highlights characteristic features of H. viridissima, such as diversification of innate immunity genes that are important for host-symbiont interactions. Thus, the H. viridissima assembly provides an important hydrozoan genome reference that will facilitate symbiosis research and better comparisons of metazoan genome architectures

Molecular analysis of self / nonself recognition in the urochordate Botryllus schlosseri

Transplantation immunity based on the recognition of MHC molecules is well described in vertebrates. Vertebrates, however, do not undergo transplantation reaction naturally. The phylogenetically closest group in which transplantation reactions can occur are the Urochordata. Therefore, these animals occupy a key position for understanding the evolution of the vertebrate immune system. When screening for genes differentially expressed during allorecognition in Botryllus schlosseri, we isolated a gene coding for a type II transmembrane protein with a C type lectin binding domain and close similarity to vertebrate CD94 and NKR-P1. Here we show that the gene, BsCD94-1, is differentially regulated during allorecognition and that a subpopulation of blood cells carries the corresponding receptor on their cell surface. Southern blot analysis using DNA from individual colonies and intronless BsCD94-1 probe reveals variation between individuals at the genomic level. CD94 in vertebrates is one of the markers for natural killer (NK) cells and binds to MHC class I molecules. NK cells play a major role in recognition and elimination of allogeneic cells. Their evolutionary origin, however, remained unknown. The results presented here indicate that the elaboration of the vertebrate immune system may have its roots in an ancestral population of cells in the urochordate blood

Response of Coral Reef Dinoflagellates to Nanoplastics under Experimental Conditions Suggests Downregulation of Cellular Metabolism

Plastic products contribute heavily to anthropogenic pollution of the oceans. Small plastic particles in the microscale and nanoscale ranges have been found in all marine ecosystems, but little is known about their effects upon marine organisms. In this study, we examine changes in cell growth, aggregation, and gene expression of two symbiotic dinoflagellates of the family Symbiodiniaceae, Symbiodinium tridacnidorum (clade A3), and Cladocopium sp. (clade C) under exposure to 42-nm polystyrene beads. In laboratory experiments, the cell number and aggregation were reduced after 10 days of nanoplastic exposure at 0.01, 0.1, and 10 mg/L concentrations, but no clear correlation with plastic concentration was observed. Genes involved in dynein motor function were upregulated when compared to control conditions, while genes related to photosynthesis, mitosis, and intracellular degradation were downregulated. Overall, nanoplastic exposure led to more genes being downregulated than upregulated and the number of genes with altered expression was larger in Cladocopium sp. than in S. tridacnidorum, suggesting different sensitivity to nano-plastics between species. Our data show that nano-plastic inhibits growth and alters aggregation properties of microalgae, which may negatively affect the uptake of these indispensable symbionts by coral reef organisms

Characterization of taxonomically restricted genes in a phylum-restricted cell type

Computational and functional genomic analyses in Hydra magnipapillata suggest that taxonomically-restricted genes are involved in the evolution of morphological novelties such as the cnidarian nematocyt

A Novel Gene Family Controls Species-Specific Morphological Traits in Hydra

Understanding the molecular events that underlie the evolution of morphological diversity is a major challenge in biology. Here, to identify genes whose expression correlates with species-specific morphologies, we compared transcriptomes of two closely related Hydra species. We find that species-specific differences in tentacle formation correlate with expression of a taxonomically restricted gene encoding a small secreted protein. We show that gain of function induces changes in morphology that mirror the phenotypic differences observed between species. These results suggest that “novel” genes may be involved in the generation of species-specific morphological traits

Species Diversity of Fish Fauna of South Bug River Basin

Установлено різноманіття іхтіофауни водойм басейну Південного Бугу, а також зональний розподіл іхтіофауни в різних притоках річок із поступовим зменшенням аборигенних видів та збільшенням інродуцентів й акліматизантів. Ці відомості підтверджують коефіцієнти схожості Серенсона й типовості угруповань іхтіофауни річкових екосистем. Дослідження засвідчує необхідність подальшого вивчення стану іхтіофауни басейну р. Південний Буг та потребує розроблення рекомендацій про реакліматизацію аборигенних видів, чисельність яких скоротилась унаслідок активного впливу антропогенних чинників. Established diversity of ichthyofauna water basin of the Southern Bug and zonal distribution of fish fauna in the various tributaries of the river, with a gradual decrease in native species and increase inrodutsentiv and aklimatyzantiv. These data confirmed the similarity coefficients Serensona typicality and groups of fish fauna of river ecosystems. Installed indicates the need for further study of the state ichthyofauna South Bug River Basin and the need to develop recommendations on re-acclimatization of native species whose numbers declined due to the active influence of anthropogenic factors.Роботу виконано на кафедрі загальної зоології та іхтіології НУБіП

NR3E receptors in cnidarians : a new family of steroid receptor relatives extends the possible mechanisms for ligand binding

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Journal of Steroid Biochemistry and Molecular Biology 184 (2018): 11-19, doi:10.1016/j.jsbmb.2018.06.014.Steroid hormone receptors are important regulators of development and physiology in bilaterian animals, but the role of steroid signaling in cnidarians has been contentious. Cnidarians produce steroids, including A-ring aromatic steroids with a side-chain, but these are probably made through pathways different than the one used by vertebrates to make their A-ring aromatic steroids. Here we present comparative genomic analyses indicating the presence of a previously undescribed nuclear receptor family within medusozoan cnidarians, that we propose to call NR3E. This family predates the diversification of ERR/ER/SR in bilaterians, indicating that the first NR3 evolved in the common ancestor of the placozoan and cnidarian-bilaterian with lineage-specific loss in the anthozoans, even though multiple species in this lineage have been shown to produce aromatic steroids, whose function remain unclear. We discovered serendipitously that a cytoplasmic factor within epidermal cells of transgenic Hydra vulgaris can trigger the nuclear translocation of heterologously expressed human ERα. This led us to hypothesize that aromatic steroids may also be present in the medusozoan cnidarian lineage, which includes Hydra, and may explain the translocation of human ERα. Docking experiments with paraestrol A, a cnidarian A-ring aromatic steroid, into the ligand-binding pocket of Hydra NR3E indicates that, if an aromatic steroid is indeed the true ligand, which remains to be demonstrated, it would bind to the pocket through a partially distinct mechanism from the manner in which estradiol binds to vertebrate ER.KK is supported by grant from Japan Society for the Promotion of Science (JSPS 17K07420). I.M.L.B and Y.C. acknowledge the support and the use of resources of the French Infrastructure for Integrated Structural Biology FRISBI ANR-10-INBS-05 and of Instruct-ERIC. AMR was supported by NIH Award R15GM114740. AMT was supported by an Internal Research and Development Award from the Woods Hole Oceanographic Institution

The innate immune repertoire in Cnidaria - ancestral complexity and stochastic gene loss

Analysis of genomic resources available for cnidarians revealed that several key components of the vertebrate innate immune repertoire are present in representatives of the basal cnidarian class Anthozoa, but are missing in Hydra, a member of the class Hydrozoa, indicating ancient origins for many components of the innate immune system

The Hydra polyp: Nothing but an active stem cell community

Hydra is a powerful stem cell model because its potential immortality and extensive regeneration capacity is due to the presence of three distinct stem cell lineages. All three lineages conform to a well-defined spatial distribution across the whole body column of the polyp. Stem cell function in Hydra is controlled by extracellular cues and intrinsic genetic programs. This review focuses on the elusive stem cell niche of the epithelial layers. Based on a comparison of the differences between, and commonalities among, stem cells and stem cell niches in Hydra and other invertebrates and vertebrates, we propose that the whole body column of the polyp may be considered a stem cell ''niche'' in which stem cell populations are established and signals ensuring the proper balance between stem cells and progenitor cells are integrated. We show that, at over 500 million years old, Hydra offers an early glimpse of the regulatory potential of stem cell niches