Vol 43, No 2 (2017)

The interest in biologically active substances (BASs) derived from marine organisms is increasing each year. These compounds are used as a basis for creating new medicines, biopreparations applied in food industry and agriculture, as well as for the production of functional foods, biologically active dietary supplements, and cosmetics. Members of the molluscan class Cephalopoda are quite promising objects for the search for new BASs. Moreover, some squid, octopus, and cuttlefish species are characterized by early onset of sexual maturity, a short lifecycle, rapid body weight gain, rapid recovery of abundance, and the ability to form dense aggregations. The substantial resources and the high species diversity make these animals a reliable source of raw materials for large-scale commercial production.

Two new species of the genus Leptochiton, L. сommandorensis sp. nov. and L. incubatus sp. nov. from north-western Pacific are described. Leptochiton сommandorensis differs from the congeners in having radial rows of granules in the lateral areas of intermediate valves, unicuspid dental cap on major lateral teeth of the radula, and dorsal scales with two ribs. Leptochiton incubatus differs from the congeners in having one aesthete pore in each granule, a shallow depression between the central and lateral areas of intermediate valves and between the antemucronal and postmucronal areas of the tail valve, and unicuspid head of major lateral teeth of radula. This species is brooding.

The utilization (possible assimilation and concentration in organs) of 99% of algal viruses from the water by the Black Sea mussel Mytilus galloprovincialis was confirmed experimentally. This index depends on the duration of the experiment, the complexity of the morphology of the virus, the age (size) of the mussels, and the presence of a nonindicatory microalga, which allows the experimental conditions to be close to natural and is conducive to the agglutination of viruses in pseudofeces and their enhanced utilization by mussels. It was found that some algal viruses concentrated by filter-feeding mussels return to the environment in the feces and are transported to the bottom (where they can be used by benthivores) or diffuse back into the pelagic zone. The results indicate that mussels have a role in the circulation of marine viruses, utilizing and transferring them from the pelagic to the benthic biotope.

The mechanisms of the adaptation of the Kildin cod to the conditions of a meromictic lake were analyzed based on the study of morphological, biological, and genetic characteristics. Significant differences between the Kildin cod and Atlantic cod have been found in their morphological and genetic characteristics. The results of an X-ray microanalysis of otoliths, which were conducted for the first time, confirm that the distribution range of the Kildin cod in Lake Mogilnoye also extends to brackish waters. It has been shown that the formation of the reproductively isolated lacustrine population of Kildin cod is accompanied by specialization in a number of characteristics (body color, feeding strategy, behavior, etc.) and by a decrease in genetic diversity.

The liver, gonads, gills, and muscles of five trophically distant charr morphs from Lake Kronotskoe, as well as silty sediments of the lake, were tested for trace-element contents. Concentrations of Mn, Fe, Ni, Cu, Zn, Rb, Sr, As, and Se were detectable in the fish tissues, while the xenobiotics Hg, Cd, and Pb were not determined. The current data indicate a strong correlation between trace-element content and the ecology of each morph and no relationship to the fish length. In the majority, the Ni, Cu, and Zn levels were strongly dependent on trophic biology. The contents of Rb, Mn, and Se were dependent on the distribution of the charr morphs along the depth gradient and correlated with the accumulation of these elements in the bottom sediments.

The lifecycle, the host–parasite system, and the ecological features of the nematode Dichelyne minutus (Rudolphi, 1819), which parasitizes invertebrates and fish in the estuarine biocenosis located at the influx of the Chornaya River into the Black Sea (off Sevastopol), have been studied. The host–parasite system of D. minutus includes the polychaete Hediste diversicolor Müller, 1776 (as an obligatory intermediate host) and nine fish species, of which seven are definitive hosts and two are accidental or captive hosts. It has been found that the lifecycle of D. minutus in the biocoenosis of the Black Sea differs from the lifecycle of this nematode that inhabits the Baltic and North seas. In the studied biocoenosis, nematode larvae occur in polychaetes and fish only in the spring and summer; no larvae are found in the autumn (the study was not conducted in the winter). The nematode parasitizes the polychaete H. diversicolor in the spring; the main source of infection in this period is obviously nematode eggs that were laid in the autumn and have overwintered in the environment. The infection process ends by early summer. The seasonal and size–age dynamics of nematode infection of the round goby, Neogobius melanostomus (Pallas, 1814), are analyzed taking the specifics of fish biology into account. The short period of infection, as characterized by the active emission of nematode larvae, their low survival in polychaetes and fish, a short lifecycle and the mortality of mature nematodes after egg-laying in the autumn result in an over-scattered distribution (mostly of the negative-binomial type) of D. minutus in populations of all the hosts.

The parameters of a hemocyte cell population were investigated in the bivalve mollusk Corbicula japonica of the Kievka River (the basin of the Sea of Japan) at four seasonal points corresponding to different stages of the reproductive cycle: (1) March (sexual rest); (2) May (gametogenesis); (3) July (spawning); and (4) November (the end of reproductive activity). Using light microscopy, we identified four cell morphotypes in the hemolymph: small and large hyalinocytes, as well as basophilic and eosinophilic granulocytes. Flow cytometry confirmed the structural heterogeneity of the cell population and allowed us to estimate the seasonal variability of the cell composition in C. japonica hemolymph. The total cell count in the mollusk hemolymph did not change significantly during the annual cycle and did not correlate with the average cell size of hemocytes. In March, May, and November, granulocytes dominated in the cell population (74.3 ± 2.9, 77.5 ± 3.5, and 86.7 ± 2.6%, respectively), while in July their relative content was reduced dramatically (37.2 ± 5.1%) causing a significant decrease of both the average cell size and granularity in circulation. Most likely, this is connected with the summer migration of mature eosinophilic granulocytes from the hemolymph to spawning gonads for resorption of the unspent sexual products, as well as to other internal organs for participation in digestion and to provide the immune defense against pathogens.

Temperature measurements in a plastic tube isolated from external influences containing an erythrocyte suspension of the scorpion fish (Scorpaena porcus Linnaeus, 1758) showed that these red blood cells are able to generate heat. Heat release in the cell suspension was expressed by a linear temperature increase in the tube during the entire experiment. Addition of extracellular ATP (1 mg mL^–1) caused the effect of a thermal shift: a sharp temperature rise in the cell suspension for 30–60 s. We believe that the heat release was caused by hydrolysis of extracellular ATP by membrane ecto-ATPase. Inhibition of ecto-ATPase activity through the addition of EDTA (1 mM) to the erythrocyte suspension led to complete blockage of heat release; the effect of the thermal shift ceased. We assume that thermal properties of red blood cells play an important role in blood hemodynamics, especially in providing the “non-Newtonian” properties of blood. The thermal phenomena observed in suspensions of fish erythrocytes open new scientific directions in exploring the capabilities of multifunctional extracellular ATP.

The complete mitochondrial genome of the Sakhalin sturgeon Acipenser mikadoi and two mitogenomes of the Amur sturgeon A. schrenckii were sequenced using Roche 454 technology. The mitogenomes of the green sturgeon A. medirostris (obtained from GenBank) and the Sakhalin sturgeon differ as much as the mitogenomes of two mtDNA haplogroups (SM and BG) found in the same population of the Amur sturgeon: 0.0042 ± 0.0006 and 0.0036 ± 0.0005 substitutions per site (Tamura–Nei distance, TrN), respectively. The differences of these mitogenome pairs from mitogenomes of sister species (kaluga A. dauricus and white sturgeon A. transmontanus) are 3–6 times larger: 0.0260 ± 0.0015 and 0.0102 ± 0.0008, respectively. Thus, the differences between the mitogenomes of the Sakhalin and green sturgeons can be attributed to the variability at the intraspecific level. The time that has passed since the divergence of the Sakhalin and green sturgeons is considered to be much shorter than was previously believed: approximately 0.16 rather than 9.60 million years.