Vol 44, No 6 (2018)

One of the modern antibacterial strategies to control various infectious pathogens in agriculture, veterinary medicine, and the food industry is the use of bacteriocins, which are potent antimicrobial peptides produced by almost all species of bacteria. The wide distribution of antibiotic-resistant bacteria, as well as the increasing awareness of the importance of the normal human biocenosis for health, necessitates the study of this new class of antimicrobial agents, whose application is recognized an alternative strategy for the treatment of infectious diseases. Among diverse marine organisms, bacteria are considered the most numerous. They are a promising source of bacteriocins, which play an important role in regulating competitive interactions in marine microbial systems. In the marine environment, with its high competition for space and resources, bacteria produce more potent bacteriocins than those isolated from other ecosystems. The scientific substantiation of the relevance of the research on the biological properties of these peptides is associated with the prospect of industrial cultivation of their producers in maricultures, as well as with the use of bacteriocins for medical and veterinary purposes.

Hybrids between the whitespotted char Salvelinus leucomaenis and the northern Dolly Varden S. malma malma have been found to regularly occur and exist in the Utkholok River in western Kamchatka and constitute a significant part of the local char stock. Initially, hybrids were recorded in 1970–1971; however, a detailed description is provided for the first time. The diagnosis, description, morphometry, and skull morphology, as well as an analysis of the mtDNA CO1 gene and nuclear TNFα gene sequences and variation in six microsatellite loci, are considered. It has been established that in some of the craniological and meristic morphological traits and genetic markers the hybrids hold an intermediate position between the whitespotted char and northern Dolly Varden, whereas in other traits they are closer to whitespotted char or northern Dolly Varden. According to data of the genetic marker analysis, the hybrids are produced by female whitespotted char and male northern Dolly Varden. It has been shown that in the Utkholok River hybridization occurs constantly due to the disruption of the prezygotic isolation mechanism. A hypothesis is made that the process of permanent hybridization and the large number of hybrids are caused by the close proximity of the spawning grounds of the whitespotted char and northern Dolly Varden in the river tributaries. During the spawning of the whitespotted char, anadromous males, as well as mature male parr of both the whitespotted char and northern Dolly Varden, form a “gamete cloud” resulting in fertilization of whitespotted char eggs.

A search for biologically active peptides has been performed in an aqueous extract of the sea anemone Urticina aff. coriacea (Cuvier, 1798) (Actiniidae) from the Sea of Okhotsk. A separation of the peptides by size-exclusion chromatography and subsequent electrophysiological testing have shown that peptides of three fractions can completely inhibit currents of mammalian ASIC1a channels. The sea anemone Urticina aff. coriacea is believed to be a promising source of novel peptides that interact with ASIC channels.

Sprat is one of the most important fish in the food webs of the open part of the Baltic Sea. It is a crucial element in the diet of predators, which include salmonid and gadoid fish, marine mammals and sea birds. Sprat might also be a source of parasitic invasion for piscivorous organisms. We evaluated the level of sprat invasion with zoonotic nematodes in the southern Baltic Sea (Polish EEZ) from two sampling periods (1987–1989–1990: 3511 fish examined; and 2015–2016: 180 fish examined). While there was no evidence for zoonotic nematode parasites in sprats sampled during the first period, or in those from 2015, we found larvae of the liver worm Contracaecum osculatum in sprat sampled in 2016 from the central off-shore area of the Polish EEZ. Together with other recent reports, this suggests that sprat recently may play a role as a transmitter of this parasite to piscivorous organisms in several areas of the Baltic Sea.

Eighteen microsatellite sequences were isolated from Platygyra acuta through magnetic bead hybridization enrichment method, and the site primers were used to analyze the genetic diversity of P. acuta, Platygyra daedalea, Favites flexuosa, and Porites lutea. Results showed that among the 18 microsatellites of P. acuta, 12 (66.67%) were perfect, 3 (16.67%) were imperfect, and the remaining 3 (16.67%) were compound type. P. acuta, P. daedalea, F. flexuosa, and P. lutea were detected to have 39, 28, 40, and 21 alleles using 12 pairs of common primers. The genetic diversity analysis of the four scleractinian populations indicated that the average polymorphism information contents were 0.5168, 0.4250, 0.5286, and 0.3409; the average expected heterozygosity values were 0.6667, 0.6042, 0.5972, and 0.4702; and the average effective numbers of allele were 2.7112, 2.5376, 2.6860, and 2.0081, respectively. All results indicated that the P. acuta and the F. flexuosa populations had high levels of genetic diversities, whereas P. daedalea and P. lutea had moderate levels of genetic diversities. In addition, environment stresses and the modes of reproduction of corals may be the main reasons for the deviation from Hardy-Weinberg equilibrium.

Larvae of Stichaeus fuscus from the Sea of Japan and the Sea of Okhotsk have been identified and their diagnostic traits described. Larvae of this species were collected in August to early October at a water temperature of 9.9–19.0°C and a salinity of 31.4–33.6‰. The size of larvae varies from 3.5 to 10.0 mm. The areas of finds of S. fuscus larvae fit the known range of this species well.

The female fertile samples of the red alga Pleuroblepharidella japonica (Okamura) M.J. Wynne from coastal waters of Matua Islet (Kurile Islands) have been found for the first time. The carposporophyte is described and illustrated; some features of development of the alga in this habitat are discussed.