Vol 45, No 6 (2019)

This paper summarizes information on the resting cysts of the dinoflagellate genus Alexandrium Halim, 1960 from the northwestern Pacific Ocean and the Chukchi Sea. Species of the genus Alexandrium, which are known as producers of paralytic toxins, cause large-scale algal blooms that pose a serious threat to marine coastal ecosystems and human health. Data are presented on the diversity, abundance, and distribution of Alexandrium spp. cysts in the Far Eastern seas of Russia and adjacent waters. The possible role of resting cysts in initiating toxic blooms of Alexandrium spp. is discussed.

The sequenced genome data from the sea urchin Strongylocentrotus purpuratus were used to identify transposons (TEs, transposable elements) and test for the presence of some of them in the genome of the sea urchin S. intermedius. The known TEs of S. purpuratus from the RepBase repeats database were used to calculate the primers and identify the corresponding TEs in the S. intermedius transcriptome. High-coverage TE sequences from the S. intermedius transcriptome were assembled based on comparison with the annotated TEs of the S. purpuratus genome. TEs with an insufficient number of reading frames in the transcriptome were beyond the analysis. The approach applied in the present study was successful: out of the 100 assembled TEs of S. intermedius, 92 corresponding TEs in the S. intermedius genome were identified using the calculated primer pairs. The TE sequences calculated by in silico methods are present in the S. intermedius genome and can be useful in further research.

This study determined the range of conditionally normal values of the catalase activity (СA) in the Black Sea red macroalga Ceramium virgatum. The level of CА in the alga corresponded to its conditionally normal functioning (26.79 ± 10.32 μg H₂O₂/(g wet weight min)). The minimum concentrations of hydrochemical parameters that correspond to the sensitivity threshold of CА in C. virgatum were found; these minimum values are 40 μM/L for organic nitrogen, 0.03 μM/L for nitrites, 0.3 μM/L for nitrates, 0.12 μM/L for inorganic phosphorus, and 0.47 μM/L for organic phosphorus.

The abundance and community structure of nirS-encoding and nirK-encoding denitrifiers inhabiting the sediment of the Pearl River Estuary was examined with quantitative PCR and high-throughput MiSeq sequencing. The results indicated that the low-oxygen condition (around 4 mg/L) of the Pearl River Estuary was the suitable environment for the denitrifying bacterial growth, and the abundances of nirS-encoding and nirK-encoding denitrifier were both highest in station P3, while the diversity and evenness were highest in stations P2 and P4, respectively. In addition, gene abundance and diversity of nirS was higher than nirK, which indicated that the denitrifying potential of nirS-encoding denitrifiers were significantly greater than that of nirK-encoding denitrifiers (p < 0.05). The most dominant nirS-encoding denitrifiers present in the sediment samples belonged to the phylum Proteobacteria, followed by Chloroflexi. However, the dominant classes of Betaproteobacteria and Gammaproteobacteria showed obvious salinity heterogeneity along the Pearl River Estuary. Betaproteobacteria have a strong survival ability in oligohaline environments and Gammaproteobacteria were opposite. Additionally, the distribution of both Betaproteobacteria and Gammaproteobacteria positively correlated with TOC and \({\text{NO}}_{2}^{ - }.\) For nirK-encoding denitrifiers, the distribution of cluster A and cluster C also showed salinity heterogeneity; the former favored oligohaline environments and the latter were opposite.

Dunaliella salina is a unicellular microalga with the potential of industrial applications. Commercial-scale cultivation of D. salina requires extensive efforts on cost reduction. This can be achieved by minimization of nutrient cost and maximization of specific growth rate and productivity. To this end, in this study, mixotrophic cultivation of D. salina on crude glycerol (by-product of calcinated-fatty acid (CaFA) production process) was investigated in shake flasks and the influences on protein, carotenoid and chlorophyll contents of the cells were studied. The highest maximum specific growth rate and biomass productivity was achieved by cultivation on 2.5 g/L crude glycerol. The protein content was more than two folds and the carotenoid content was more than 60% higher than that of autotrophic cultivation. Subsequently, continuous cultivation of D. salina on crude glycerol in a helical photobioreactor was performed at the dilution rate of 0.52/d. The biomass productivity of 2.3 × 10⁶ cell/(mL d) was achieved which was more than 75% of the values for previously reported autotrophic cultivations. Conclusively, continuous cultivation of D. salina on by-product of CaFA production process could be a potential process technology for production of D. Salina.

The composition of leukocytes was studied in the peripheral blood and hematopoietic organs (kidneys and spleen) of the Antarctic starry skate Amblyraja georgiana (Norman, 1938). Cells of several types with different morphofunctional characteristics and structures were found in the blood smears: lymphocytes, monocytes, neutrophils and eosinophils, and blast cells. A leukogram analysis showed that the white blood of A. georgiana is of a lymphoid type. In the kidney and spleen, most cells are blast forms.

Chum salmon (Oncorhynchus keta) is an endangered species in China. The numbers of chum salmon have declined sharply in the wild, especially the population entering into the Tumen River (Jilin Province) which is the boundary river between China and North Korea. In order to solve the conflict between China and North Korea about the ownership of the population, we developed ten novel microsatellite loci for future studies of paternity identification.The result showed that the observed and expected heterozygosity ranges were 0.480–0.900 and 0.645–0.885, respectively. The polymorphic information content (PIC) ranged from 0.595 to 0.864, with a mean of 0.776.