Том 44, № 3 (2018)

In this review, the results of the study of marine benthic algal flora of Hainan Island, China, during the period from 1933 to 2015 are considered. It has been found that the local floristic diversity and taxonomic composition are similar to those of macroalgae from other large islands of the Indo-Pacific, where coral reefs are the main ecosystem of the shallow-water zone. An analysis of historical (decadal) changes in the marine benthic flora of Hainan has shown the following pattern of variations in the species diversity of macroalgae since the middle of the 20th century: a decline in low-productive epilithic algae with voluminous forms of thalli and an increase in highly productive opportunistic species with filamentous, fine filamentous, and membranous forms. These historical changes are thought to be caused by human impacts: inappropriate exploitation of coral reefs and eutrophication of coastal waters due to household sewage from large cities and discharge of mariculture wastes.

This paper presents results from a study of phytoplankton communities that was performed in 2015 at 213 stations in the southwestern part of the Kara Sea. The values of primary production at most stations exceeded the estimates obtained in 1993 by several times. A continued increase in productivity indices and no outbreaks of phytoplankton were consistent with long-term satellite monitoring data. At the same time, grouping of stations showed a highly mosaic structure of the spatial distribution of phytoplankton and a significant range of variation of most of the studied parameters.

The state of waters in Peter the Great Bay, Sea of Japan, and Nha Trang Bay, South China Sea, has been assessed according to the following microbiological parameters at the sites that differ in their degrees of anthropogenic impact: spectra of substrate consumption determined by the method of multi-substrate testing (MST) and the abundance of some indicator bacteria. The results of mathematical processing of the spectra of substrate consumption by microorganisms in the studied waters showed the main characteristics of secure well-functioning water ecosystems and systems under the influence of external factors. The cleanest water sites were characterized by the maximum values of the ecosystem health index and the minimum values of the number of conditionally pathogenic bacteria. Consequently, the data obtained through determination of the spectra of substrate consumption by marine microflora reflect the actual ecological and epidemiological situation in the water area and can be used in monitoring of marine waters.

This study examines the interaction between two types of phagocytes (P1 and P2) of the holothurian Eupentacta fraudatrix and its in vitro modulation by dexamethasone. Our results indicate that inhibition of apoptosis in P1 phagocytes by P2 phagocytes was accompanied by increased activities of antioxidant enzymes and reduced synthesis of interleukin-1α-like substances. We hypothesize that P1-phagocyte-related effects occurred in response to a high level of hydrogen peroxide produced by P2 phagocytes. The reduced anti-apoptotic effect of P2-phagocyte supernatant during prolonged incubation (24 h) was accompanied by a decline in defense reactions in P1 phagocytes due to depletion of antioxidant enzymes (catalase, glutathione reductase, and glutathione transferase). Inhibition of apoptotis in P1 phagocytes associated with upregulation of antioxidant enzyme defense in response to P2 phagocytes preincubated with dexamethasone (100 µM) indicates that P2 phagocytes affect P1 phagocytes via a ROS-associated mechanism. Thus, our data provide evidence that P1 and P2 phagocytes exhibit their maximum activity at different stages of the immune response, thus causing inhibition of activity in target cells during prolonged exposure. Dexamethasone enhances these effects.

The free amino-acid contents of the apical and middle parts of the thallus, as well as the receptacles of fertile and juvenile specimens, of the brown alga Fucus vesiculosus collected from seven different biotopes of the Murman shore, Barents Sea have been studied for the first time. The free amino-acid composition of the studied algae specimens was dominated by alanine, along with aspartic and glutamic acid. The distribution of free amino acids in the thallus of Fucus is uneven and depends on the habitat. The free aminoacid contents in the spring vary considerably between different parts of the thallus; however, certain regular patterns of their distribution are observed. A correlation has been found between the level of some individual amino acids in different parts of the thallus of fertile and juvenile algae and the salinity of the seawater.

Shrimp lysozyme is as an antibacterial enzyme that participates in the innate defense against the invasion of bacterial pathogens. In this study, the lysozyme gene from hemocytes of the shrimp Marsupenaeus japonicus was isolated and characterized. The M. japonicus lysozyme (MjLys) encodes a polypeptide of 158 amino acids (aa) that includes an 18 aa signal peptide. The gene fragment encoding the mature MjLys protein was subcloned into the expression vector pET-32a(+) and transformed into E. coli BL21(DE3)pLysS, and the protein was strongly expressed in insoluble inclusion bodies. Following extraction using urea, the denatured recombinant protein was refolded by on-column Ni²⁺ affinity chromatography or dialysis with a gradient of decreasing urea concentration. Approximately 50% of the recombinant MjLys was successfully refolded into monomeric protein using urea gradient dialysis, while 30% was salvaged using on-column refolding. Purified MjLys exhibited significant antibacterial activity against Gram-positive bacteria Micrococcus lysodeikticus and Staphylococcus aureus. This efficient over-expression and refolding method can provide the large quantities of biologically active protein required for further biochemical and structural studies and potential biotechnological applications.