卷 52, 编号 4 (2016)

Using fishes (32 species, 11 families) as an example, the relationship between the taste attractiveness of free amino acids (L-isomers) and their physicochemical and biological properties was analyzed. It was shown that essential amino acids, most nutritionally required for an organism, have lower taste attractiveness for fishes than nonessential amino acids. Only in 6 of the 32 tested species (sunbleak Leucaspius delineatus, European minnow Phoxinus phoxinus, dace Leuciscus leuciscus, chub Leuciscus cephalus, blue gourami Trichopodus trichopterus, pearl gourami Trichopodus leerii) the relationship between the taste attractiveness and molecular weight of amino acids was supported statistically, being negative in all cases. Only in 2 species, a statistically significant correlation between the taste properties of amino acids and the dissociation constant (K₁) was found, positive in the stone loach Barbatula barbatula and negative in the lake char Salvelinus namaycush. A positive correlation between taste preferences and the magnitude of the isoelectric point (pI) of amino acids was found in one species (roach Rutilus rutilus) and a negative correlation in 2 species (brown trout Salmo trutta and Arctic char Salvelinus alpinus erythrinus). A statistically significant correlation between the taste attractiveness and water solubility of amino acids was revealed in 2 species (chum salmon Oncorhynchus keta and navaga Eleginus nawaga), negative in both cases. The flavor, which stimulates food intake, was found to be more often intrinsic to acidic and polar uncharged than basic and nonpolar amino acids, L- than D-isomers, amino acids with an amino group at the α- than β-position. Amino acids are more attractive than their salts. Aromatic amino acids are much less attractive than S-containing or acyclic amino acids. Thus, in most fish species there is no or weak relationship between the taste attractiveness of free amino acids and many of their physical, chemical and biological properties, suggesting a mediated character of this relationship and/or its poor detectability.

The composition and content of carotenoids in tissues of Anadara kagoshimensis (Tokunaga, 1906) were analyzed under food deprivation over 30 days. By the end of the experiment, a little and uneven decrease in the total carotenoid level was observed in the foot, hepatopancreas, gills, and tissue remainder. Initially, β-carotine, pectenolon, zeaxanthine, diatoxanthine, alloxanthine and the ethers of the latter four carotenoids were detected in tissue extracts. The qualitative carotenoid composition in the tissues under study was similar. During the experiment, changes common to all tissues were found both in the composition and content of carotenoids. β-carotene disappeared on days 3–4, the level of pectenolon, zeaxanthine, diatoxanthine and alloxanthine ethers decreased over 30 days, while the pectenolon and alloxanthine levels increased. Tissue specificity was revealed. Specifically, in the foot and hepatopancreas, a considerable increase was observed in the pectenolon and alloxanthine levels parallel to the decreasing total level of carotenoid esthers and increasing level of diatoxanthine and zeaxanthine; in the gills and lump of the remaining tissues, at the similar increase in the pectenolon and alloxanthine levels, those of diatoxanthine and zeaxanthine remained intact or even a little below the initial level. The diagram of carotenoid transformation in Anadara kagoshimensis is supplemented.

Ecdysteroids are multifunctional hormones regulating virtually all morphogenetic events in insects. Their role in stress and immune response regulation is not well researched. Here we study the effect of 20-hydroxyecdysone on antimicrobial peptide synthesis in the larvae of Calliphora vicina. An inverse correlation was observed between the 20-hydroxyecdysone titer and antimicrobial peptide concentration in the hemolymph of naïve and bacteria challenged maggots. High and low doses of 20-hydroxyecdysone, injected simultaneously with bacterial cells, had an opposite effect on antimicrobial peptide synthesis in the diapausing larvae. Morphogenetically effective doses of 20-hydroxyecdysone demonstrated immunosuppressive activity. A low dose of 20-hydroxyecdysone, on the contrary, moderately stimulated antimicrobial peptide synthesis. The data suggest that ecdysteroids are directly involved in the regulation of the immune system activity and that the final effect is dose-dependant.

Sleep is characterized by cycling and consecutive alternation of different phases and stages, each of which features intrinsic changes in autonomic regulation with heart rate oscillations; this may cause heart rhythm disorders, especially in the presence of comorbidities. This review addresses the issues of interrelationship between cardiac conduction disorders and obstructive sleep apnea. It is shown that some mechanisms of bradyarrythmia emergence (first of all, features of autonomic regulation with increases in parasympathetic tone) under respiratory arrest during sleep are also inherent to human divers as well as aquatic or para-aquatic mammals that have to hold their breath when diving or staying under water for a long time. These mechanisms may fulfill the defense function.

Literature and own data on central effects of regulatory peptides (155 substances from 32 families) have been analyzed. Peptides produced by peripheral tissues affect the brain through the almost impermeable for them blood–brain barrier and evoke numerous central effects. The mechanisms of this impact are as follows: peptides bind to specific receptors located on vagal afferent terminals and in the circumventricular organs as well as (to a lesser extent) penetrate into the brain with the aid of specific transport systems or by simple diffusion. The number of these trans-barrier communications depends on the evolutionary age of the regulated physiological function: the more ancient the function is, the greater number of peripheral peptides are involved in such trans-barrier communications.