Milky hemolymph syndrome (MHS) associated with a virus in tanner crab Chionoecetes bairdi off the Pacific coast of Kamchatka.

Milky hemolymph syndrome (MHS) caused by a bacilliform virus (BV) was found in tanner crab Chionoecetes bairdi in the shelf zone of Kamchatka. The prevalence of the disease varied from 0.18 to 1.02%. A total lesion of the cells of the interstitial connective tissue and the connective tissue component of all internal organs was noted, which was expressed in the hypertrophy of their nuclei. In addition, hypertrophy of fixed phagocytes and circulating hemocytes was noted. Ultrastructural analysis of the tissues confirmed that in the interstitial connective tissue of pathologically altered organs, virus particles of two morphotypes were found - rod-shaped and globular. In the cytoplasm of infected cells, bands of microtubules formed near where viral particles were concentrated. In the area of contacts at the poles of microtubules, successive stages of the transformation of rod-shaped viruses into globular viruses was observed. The bacilliform virus that infects C. bairdi is structurally very similar to CoBV found in Chionoecetes opilio. Structural features are characteristic of representatives of fam. Nimaviridae. The molecular data obtained suggest that the virus causing MHS in C. bairdi is systematically very close, if not identical, to CoBV.

Biogenic synthesis of selenium and tellurium nanoparticles by marine bacteria and their biological activity.

Selenium (SeNPs) and tellurium nanoparticles (TeNPs) were synthesized by green technology using the three new bacterial marine isolates (strains PL 2476, AF 2469 and G 2451). Isolates were classified as Pseudoalteromonas shioyasakiensis according to 16S rRNA sequence analysis, morphological characteristics, and biochemical reactions. The bioreduction processes of isolates were studied in comparison with the previously described Alteromonas macleodii (strain 2328). All strains exhibited significant tolerance to selenite and tellurite up to 1000 µg/mL. A comparative analysis of the bioreduction processes of the isolates demonstrated that the strains have a high rate of reduction processes. Characterization of biogenic red SeNPs and black TeNPs using scanning electron microscopy (SEM), EDX analysis, Dynamic Light Scattering, and micro-Raman Spectroscopy revealed that all the isolates form stable spherical selenium and tellurium nanoparticles whose size as well as elemental composition depend on the producer strain. Nanoparticles of the smallest size (up to 100 nm) were observed only for strain PL 2476. Biogenic SeNPs and TeNPs were also characterized and tested for their antimicrobial, antifouling and cytotoxic activities. Significant antimicrobial activity was shown for nanoparticles at relatively high concentrations (500 and 1000 µg/mL), with the antimicrobial activity of TeNPs being more significant than SeNPs. In contrast, against cell cultures (breast cancer cells (SkBr3) and human dermal fibroblasts (HDF) SeNPs showed greater toxicity than tellurium nanoparticles. Studies have demonstrated the high antifouling effectiveness of selenium and tellurium nanoparticles when introduced into self-polishing coatings. According to the results obtained, the use of SeNPs and TeNPs as antifouling additives can reduce the concentration of leachable biocides used in coatings, reducing the pressure on the environment.

First detection of Hematodinium sp. In spiny king crab Paralithodes brevipes, and new geographic areas for the parasite in tanner crab Chionoecetes bairdi, and red king crab Paralithodes camtschaticus.

A parasitic dinoflagellate of the genus Hematodinium was found off the Pacific coast of Kamchatka in three species of crabs: red king crab Paralithodes camtschaticus, tanner crab Chionoecetes bairdi, and spiny king crab Paralithodes brevipes. This is the first detection of Hematodinium in spiny king crab. The results of the genetic analysis showed that the pathogen found in P. brevipes, P. camtschaticus, and C bairdi from the Avacha and Kronotsky bays off the Pacific coast of Kamchatka was the same or very close to the Hematodinium sp., which infects many species of crustaceans in the Northern Hemisphere. The prevalence of infection was 0.2% for tanner crabs and 2.7% for red king crabs. Due to a limited sample size, we were unable to calculate the prevalence for spiny king crabs and female red king crabs. Both the macroscopic and microscopic signs of the pathology were similar in all diseased crabs. The differences in the micromorphology of the Hematodinium cells we found in the three crab species, including the presence or absence of trichocysts, the shape of the plasmodia, and the structure of pore complexes, are most likely related to the life cycle and the physiology of the parasite. The results of the genetic analysis showed that the pathogen found in P. brevipes, P. camtschaticus, and C. bairdi from the Avacha and Kronotsky bays of the Pacific coast of Kamchatka was the same or very close to the Hematodinium sp., which infects many species of crustaceans in the Northern Hemisphere.

First record of new rickettsia-like organism in the blue king crab Paralithodes platypus from the Sea of Okhotsk: Distribution, morphological evidence and genetic analysis.

An infection caused by a rickettsia-like organism (RLO) was detected in the blue king crab Paralithodes platypus from the eastern Sea of Okhotsk. The external signs of the disease are lethargy and an empty gastrointestinal tract. Dissection of infected individuals revealed that their hepatopancreas was light yellow in color. The causative agent of infection is Gram-negative rod-shaped bacterium targeted exclusively at hepatopancreas tissues. In the cytoplasm of infected cells, the bacteria are enclosed in parasite vacuoles or located immediately in cytosol. An ultrastructural analysis showed two main morphological types corresponding to the life cycle stages in the RLO: the vegetative stage of intermediate bodies, characterized by growth and division processes, and the infection stage of elementary bodies, which are spore-like non-dividing short rods surrounded by a multilayered membrane and having an osmiophilic inclusion body. At the terminal stage of infection, as a result of lysis of the infected cells, the RLO enters the lumen of the hepatopancreatic tubules which contributes to the spread of infection. According to genetic analysis based on 16S rRNA gene sequences, the RLO from P. platypus is most closely related to the Candidatus Hepatobacter penaei, NCBI #JX981946 (94.7% similarity) and NCBI #KY363553 (94.1% similarity). The high level of genetic differences (more than 5%) of the studied pathogen, along with the structural features, allows characterizing the RLO isolated from P. platypus as a new species of the genus Candidatus Hepatobacter paralithodi nov. sp., NCBI #MK928971.

[Fish growth hormone genes: Divergence of coding sequences in salmonid fishes].

Comparison of coding nucleotide sequences of the paralogous GH1 and GH2 genes, as well as of the growth hormone amino acid sequences, in the species of closely related salmonid genera Salvelinus, Oncorhynchus, and Salmo was performed. It was demonstrated that, in different groups of salmonids, the amino acid substitution rates were considerably different. In some cases, an obvious discrepancy between the divergence of growth hormone genes and phylogenetic schemes based on other methods and approaches was revealed. These findings suggest that the reason may be multidirectional selection at duplicated genes at different stages of evolution.

[Genetic Differentiation of Pacific Smelt Osmerus mordax dentex Inferred from the Data of Mitochondrial DNA Analysis].

The population genetic structure of Pacific smelt Osmerus mordax dentex from 25 locations in the Sea of Japan, Okhotsk Sea, Bering Sea, Kara Sea, Barents Sea, and White Sea was examined based on mitochondrial DNA variability. The genetic structuring of O. m. dentex over the larger part of the examined Eurasian range was weakly expressed, despite the high level of haplotype diversity (0.770 +/- 0.154). Hierarchical analysis of molecular variance (AMOVA) showed that the majority of molecular diversity (89%) was found within the populations. The most considerable differentiation of geographical populations for those grouped by their association with sea basins was observed for the Sea of Japan; with mean phi(ST) values of 0.114 (based on data from restriction fragment length polymorphism (RFLP) analysis) and 0.115 (based on sequencing data) (p < 0.01).

Reproduction-related effects of green alga Coccomyxa sp. infestation in the horse mussel Modiolus modiolus.

The effects of Coccomyxa sp. infestation on the reproductive characteristics of the horse mussel Modiolus modiolus from the north-western Pacific (Peter the Great Bay, Sea of Japan) are demonstrated in this study. The mussels were collected monthly from May to September of 2009, and the prevalence of females and males with green tissues was 39% and 47%, respectively. Overall, the green alga infection caused a mild effect on gametogenesis in the horse mussel. The dynamics of gonad development in the healthy and infected mussels during the study period was generally similar, with the spawning being partial and occurring from the beginning of June to the first half of September; total spawning was recorded at the end of this period. However, several negative reproduction-related effects of the green alga infestation were observed, i.e., general gonadal underdevelopment, which was apparent from significant decrease in the acinus areas of the ovaries and testes and an increase in the connective tissue layer between the acini, a delay in some stages of the reproductive cycle and production of decreased number of spermatozoa and large vitellogenic oocytes, especially in the early spawning period (June). All of these results suggest a reduced reproductive output for the infected mussels.

Phylogenetic and morphological characterization of the green alga infesting the horse mussel Modiolus modiolus from Vityaz Bay (Peter the Great Bay, Sea of Japan).

In this work, the ultrastructural features and taxonomic position of the green microalga infesting the horse mussel Modiolus modiolus from the north-western Pacific (Vityaz Bay, Peter the Great Bay, Sea of Japan) are reported. Mussels were collected monthly from May to September of 2009. In different months, the prevalence of mussels with green tissues was 16.6-62.5% (mean 43%). The most affected organs were the mantle, digestive gland and gonad. Histological analysis revealed severe infiltration of the connective tissue by hemocytes containing the alga cells. Electron microscopy showed that the alga was morphologically similar to the green algae from the genus Coccomyxa (Chlorophyta: Chlorococcales). Two new primers were designed to generate partial small subunit (SSU) rRNA sequences of the green alga from M. modiolus. Phylogenetic analysis based on the comparison of the SSU rRNA sequences of the trebouxiophyceans confirmed an affiliation of the green alga with the genus Coccomyxa. The sequence (1296 bases) of the green alga from M. modiolus was most closely related to the sequence CPCC 508 (AM981206) (identity 100%), obtained from an acid-tolerant, free-living chlorophyte microalga Coccomyxa sp. and to the sequences EU127470 (identity 99.3%) and EU127471 (identity 99.7%) of the green alga, presumably the true Coccomyxa parasitica, infecting the blue mussel Mytilus edulis from the Flensburg Fjord (North Atlantic).

Hematodinium sp. infection of red Paralithodes camtschaticus and blue Paralithodes platypus king crabs from the Sea of Okhotsk, Russia.

A disease caused by a parasitic dinoflagellate of the genus Hematodinium was identified in red, Paralithodes camtschaticus, and blue, Paralithodes platypus, king crabs from the north-east region of the Sea of Okhotsk, Russia, during annual stock surveys. No carapace color change was observed even in heavily infected crabs, but diseased crabs possessed creamy-yellow hemolymph, which was visible through the arthrodial membranes of the abdomen and appendages. Several stages of the parasite's life history, including trophonts, plasmodia, sporonts and macrodinospores, were observed in tissues of infected king crabs. Numerous parasite cells were observed in the lumina of the myocardium, the gills, the connective tissue of antennal glands and the sinuses of nerve ganglia, eyestalks and gastrointestinal tract of king crabs with gross signs of infection. Based on sequencing of the 18S rDNA, it appears that the Hematodinium sp. found in red and blue king crabs is identical or closely related to Hematodinium sp. isolated from crabs of the genera Chionoecetes and Lithodes. Observed prevalences were 0.33% in sublegal male red king crabs, 0.18% in female red king crabs, 0.34% in sublegal male blue king crabs and 0.31% in female blue king crabs.