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There are increasing findings of the bivalve transmissible neoplasia derived from the Pacific mussel Mytilus trossulus (MtrBTN) in populations of different Mytilus species worldwide. The Subarctic is an area where this disease has not yet been sought despite the fact that Mytilus spp. are widespread there, and M. trossulus itself is a boreal species. We used flow cytometry of the hemolymph, hemocytology, and histology to diagnose disseminated neoplasia in a sample of M. trossulus from Magadan in the subarctic Sea of Okhotsk. Neoplasia was identified in 11 of 214 mussels studied. Using mtDNA COI sequencing, we revealed genotypes identical or nearly identical to known MtrBTN ones in the hemolymph of most of the diseased mussels. Both MtrBTN evolutionary lineages have been identified, the widespread MtrBTN2, and MtrBTN1, so far only known from M. trossulus in British Columbia on the other side of the Pacific from Magadan. In addition, MtrBTN2 was represented by 2 common diverged mtDNA haplolineages. These conclusions were confirmed for selected cancerous mussels by molecular cloning of COI and additional nuclear and mtDNA genes. On the background of high genetic diversity, different cancers were similar in terms of ploidy (range 4.0–5.8 n) and nuclear-to-cell ratio. Our study provides the first description of neoplasia and MtrBTN in mussels from the Sea of Okhotsk and from the Subarctic, of both MtrBTN1 and MtrBTN2 in the same mussel population, and the first direct comparison between these transmissible cancers.

Transmissible cancers are malignant cell clones that spread among individuals through transfer of living cancer cells. Several such cancers, collectively known as bivalve transmissible neoplasia (BTN), are known to infect and cause leukaemia in marine bivalve molluscs. This is the case of BTN clones affecting the common cockle,Cerastoderma edule, which inhabits the Atlantic coasts of Europe and north-west Africa. To investigate the origin and evolution of contagious cancers in common cockles, we collected 6,854C. edulespecimens and diagnosed 390 cases of BTN. We then generated a reference genome for the species and assessed genomic variation in the genomes of 61 BTN tumours. Analysis of tumour-specific variants confirmed the existence of two cockle BTN lineages with independent clonal origins, and gene expression patterns supported their status as haemocyte-derived marine leukaemias. Examination of mitochondrial DNA sequences revealed several mitochondrial capture events in BTN, as well as co-infection of cockles by different tumour lineages. Mutational analyses identified two lineage-specific mutational signatures, one of which resembles a signature associated with DNA alkylation. Karyotypic and copy number analyses uncovered genomes marked by pervasive instability and polyploidy. Whole-genome duplication, amplification of oncogenesCCND3andMDM2, and deletion of the DNA alkylation repair geneMGMT, are likely drivers of BTN evolution. Characterization of satellite DNA identified elements with vast expansions in the cockle germ line, yet absent from BTN tumours, suggesting ancient clonal origins. Our study illuminates the evolution of contagious cancers under the sea, and reveals long-term tolerance of extreme instability in neoplastic genomes.

Two lineages of bivalve transmissible neoplasia (BTN), BTN1 and BTN2, are known in blue mussels Mytilus. Both lineages derive from the Pacific mussel M. trossulus and are identified primarily by their unique genotypes of the nuclear gene EF1α. BTN1 is found in populations of M. trossulus from the Northeast Pacific, while BTN2 has been detected in populations of other Mytilus species worldwide but not in M. trossulus itself. Here we examined M. trossulus from the Sea of Japan (Northwest Pacific) for the presence of BTN. Using hemocytology and flow cytometry of the hemolymph, we confirmed the presence of disseminated neoplasia in our specimens. Cancerous mussels possessed the BTN2 EF1α genotype and two mitochondrial haplotypes with different recombinant control regions, similar to that of common BTN2 lineages. This is the first report of BTN2 in its original host species M. trossulus. A comparison of all available BTN and M. trossulus COI sequences suggests a common and recent origin of BTN2 diversity in populations of M. trossulus outside the Northeast Pacific, possibly in the Northwest Pacific.

Two lineages of bivalve transmissible neoplasia (BTN), BTN1 and BTN2, are known in blue musselsMytilus. Both lineages derive from the Pacific musselM. trossulusand are identified primarily by the unique genotypes of the nuclear gene EF1α. BTN1 is found in populations ofM. trossulusfrom the Northeast Pacific, while BTN2 has been detected in populations of otherMytilusspecies worldwide but not inM. trossulusitself. The aim of our study was to examine musselsM. trossulusfrom the Sea of Japan (Northwest Pacific) for the presence of BTN. Using hemocytology and flow cytometry of the hemolymph, we confirmed disseminated neoplasia in our specimens. Cancerous mussels possessed the unique BTN2 EF1α genotype and two mitochondrial haplotypes with different recombinant control regions, similar to that of common BTN2 lineages. This is the first report of BTN2 in its original host speciesM. trossuluspopulations in West Pacific may be the birthplace of BTN2 and a natural reservoir where it is maintained and whence it spreads worldwide. A comparison of all available BTN andM. trossulusCOI sequences suggests a common and recent, though presumably prehistoric origin of BTN2 diversity in populations ofM. trossulusoutside the Northeast Pacific.

The distribution of two common intertidal amphipod speciesGammarus oceanicusandGammarus setosuswas studied along the coast of Svalbard Archipelago. Genetic analysis showed geographical homogeneity ofG. oceanicuswith only one molecular operational taxonomic unit (MOTU) and much higher diversification ofG. setosus(5 MOTUs) in the studied area. Only two MOTUs ofG. setosusare widespread along the whole studied Svalbard coastline, whereas the remaining three MOTUs are present mainly along the northern and eastern parts of archipelago’s largest island, Spitsbergen. Distribution analysis indicates that the demographic and spatial expansion ofG. oceanicusin the northern Atlantic has started already during the Last Glacial Maximum (LGM, ca. 18 ka), whileG. setosusseems to be a long-persistent inhabitant of the Arctic, possibly even through the LGM, with slower distribution dynamics. Combining the results of our molecular study with previous field observations and the knowledge upon the direction of ocean currents around the Svalbard Archipelago, it can be assumed thatG. oceanicusis a typical boreal Atlantic species that is still continuing its postglacial expansion northwards. In recent decades it colonized High Arctic due to the climate warming and has partly displacedG. setosus, that used to be the only common gammarid of the Svalbard intertidal zone.

One of the clinicians’ major concerns is the biological safety of MSC. The critical question for clinical application of human MSC is their ability to undergo spontaneous malignant transformation in a recipient organism. The goal of our research was to study umbilical cord hMSC proliferative and differentiation capacities, karyotype stability, telomerase activity and telomere length, oncomarkers expression and tumorigenicity during long-term (6 months) cultivation ex vivo. Here we report on the establishing the primary culture of human umbilical cord MSC, MSC_0714, that was capable to proliferate ex vivo for up to 59 passages (6 months). During this period, the cells preserved their normal karyotype, morphology and MSC immunophenotype. Telomeres started to shorten only after the passage 20, while hTERT was inactive in these cells for the whole period of expansion. At the beginning of cultivation the number of SA-β-gal positive cells did not exceeded 3-5%, after the 22th passage their number started to increase and reached 49% at the passage 57. Thus, it was shown that MSC during long-term culture retain their characteristics and undergo cell senescence.

Sea stars Asterias rubens are important natural enemies of the blue mussel Mytilus in the North Atlantic. We asked whether these predators distinguish between the cryptic species M. edulis and M. trossulus that occur sympatrically in the White Sea. In mixed experimental stocks, the odds of being eaten by sea stars were about four times greater for M. trossulus. We also showed that A. rubens preferred smaller mussels to larger ones, irrespective of their species affinity. Our findings support earlier indirect observations showing that sea stars recognize M. trossulus as a more preferable prey than M. edulis. Dramatic differences in the vulnerability to sea star predation may explain the segregation of habitats between the two mussel species in contact zones; M. trossulus usually tends to occupy habitats where the sea star predators are scarce.

Four exons of the CgFrep1 gene (3333 bp long) encode a putative fibrinogen-related protein (324 aa) bearing a single C-terminal FBG domain. Transcripts of the gene obtained from hemocytes of different Pacific oysters show prominent individual variation based on SNP and indels of tandem repeats resulted in polymorphism of N-terminus of the putative CgFrep1 polypeptide. The polypeptide chain bears N-terminal coiled-coil region potentially acting as inter-subunit interface in the protein oligomerization. It is suggested that CgFrep1 gene encodes the oligomeric lectin composed of at least two subunits.

Populations of marine bivalves are known to be unstable but it is unclear whether this instability has internal or external causes. In this paper we summarize results from long-term (1978–2007) monitoring of an Astarte borealis (Astartidae) population in the White Sea. We sought significant long-term changes among a population of subtidal clams existing under relatively stable conditions. The studied population was initially (in 1978–1995) formed exclusively by adult clams, with no recruitment occurring until a mass inflow of unidentified astartid’s juveniles in the late 1990s. We assessed the suitability of periostracum microsculpture for identification of astartid juveniles and identified the juveniles recruited the population as A. borealis. Thus significant changes in population structure were detected. Our study suggests that A. borealis may have a very long life span (>20 years) and a prolonged recruitment failure could be associated with scarcity of hard substrates needed for egg attachment in a silted environment. As old clams died, their valves provided a hard substrate on the bottom surface, facilitating recruitment. We propose a new conceptual model of subtidal clams’ population dynamics predicting long-term cyclic changes driven by internal mechanisms associated with an unusual type of positive influence of adults upon recruits.

Preliminary survey of lichen flora was carried out in the Kologriv District of Kostroma Region. The territory of Kologrivsky Les Nature Reserve and vicinity of Burdovo village were investigated. Totally 162 species of lichens and allied fungi were recorded, 95 of them were found within the nature reserve.