High level of genetic divergence between sympatric color morphs of the littoral sea anemone Anthopleura orientalis (Anthozoa: Actiniaria)

Using enzyme electrophoresis and nematocyst analysis, the sympatrically occurring "light" and "dark" color morphs of the sea anemone Anthopleura orientalis from the Sea of Japan were shown to be two valid species. The "light" morph was identified as A. orientalis (Averintsev, 1967 Issledovaniya fauny morei: Vyp. 5 (13). Nanka, Leningrad, pp. 62-77), while the "dark" morph was designated as Anthopleura sp. The analysis of 21 isozyme loci revealed high value of Nei's genetic distance (D=1.284) between the two species, which are indistinguishable in their external morphology. The mean values of observed and expected heterozygosities for A. orientalis and Anthopleura sp. are high (H(o)=0.252+/-0.061, H(e)=0.250+/-0.061 and H(o)=0.327+/-0.052, H(e)=0.351+/-0.054, respectively). The species differ significantly in the size of spirocysts and nematocysts, among which the atrichs from acrorhagi and the basitrichs from actinopharynx contribute most to the observed difference. Strong qualitative difference is revealed between distributions of nematocysts in mesenteric filaments of the two sea anemone species studied. The possible conspecificity of Anthopleura sp. with Anthopleura artemisia (Dana, 1848) is discussed and the conclusion made that these are two separate species.     

Nootropic and analgesic effects of Semax following different routes of administration

Heptapeptide Semax (MEHFPGP) is the fragment of ACTH(4-10) analogue with prolonged neurotropic activity. The aim of the present work was to study the Semax effects on learning capability and pain sensitivity in white rats following intraperitoneal and intranasal administration in different doses. Semax nootropic effects were studied in the test of acquisition of passive avoidance task. Pain sensitivity was estimated in Randall-Selitto paw-withdrawal test. It was shown that Semax exerts nootropic and analgesic activities following intraperitoneal administration. Analysis of dependence of these effects on dose resulted in different dose-response curves. Following intranasal administration, Semax was more potent in learning improvement compared to intraperitoneal administration. The peptide failed to affect the animal pain sensitivity following intranasal administration as opposed to intraperitoneal administration. The data obtained suggest different mechanisms and brain structures involved in realization of the nootropic and analgesic effects of Semax.     

The Protective Effect of Semax in a Model of Stress-Induced Impairment of Memory and Behavior in White Rats

The effect of acute restrained stress on cognitive functions and anxiety-like behavior in white rats has been studied; furthermore, the influence of the fragment ACTH(4–10) analog Semax on the stress effects was evaluated. It was shown that stress exposure leads to impaired retention of previously acquired food-motivated maze task as well as reduced anxiety-like behavior in the elevated plus maze in rats. Preliminary intraperitonial administration of Semax (0.1 mg/kg) attenuates cognitive impairment caused by acute restrained stress, but it does not affect stress-induced changes in anxiety.     

Atomic force microscopy study of red blood cell membrane nanostructure during oxidation‐reduction processes

The morphology and functional state of red blood cells (RBCs) mainly depends on the configuration of the spectrin network, which can be broken under the influence of intoxication because of oxidation processes in the cells. Measurement of these processes is a complex problem. The most suitable and prospective method that resolves this problem is atomic force microscopy (AFM). We used AFM to study the changes in the spectrin matrix and RBC morphology during oxidation processes caused by ultraviolet (UV) irradiation in RBC suspension. The number of discocytes decreased from 98% (in control) to 12%. We obtained AFM images of the spectrin matrix in RBC ghosts. Atomic force microscopy allows for the direct observation and quantitative measurement of the disturbances in the structure of the spectrin matrix during oxidation processes in RBCs. The typical section size of the spectrin network changed from approximately 80 to 200 nm (in control) to 600 nm and even to 1000 nm after UV irradiation. An AFM study showed that incubation of RBCs with Cytoflavin® after UV irradiation preserved the forms of RBCs almost at control levels; 89% of the cells remained as discocytes. To quantify the intensity of the oxidation‐reduction processes, the percentage of haemoglobin derivatives was measured. The content of methaemoglobin varied in the range of 1% to 70% during the experiments. These evidence‐based studies are important for the fundamental research of interactions during redox processes in RBCs at the molecular level.     

Genetic divergence between three sea urchin species of the genus Strongylocentrotus from the Sea of Japan

Intraspecific allozymic variation and interspecific genetic divergence were studied in three sea urchin species of the genus Strongylocentrotus (S. intermedius, S. nudus, S. pallidus) from the Sea of Japan. S. pallidus and S. intermedius showed high mean values of expected heterozygosity, H(e)=0.223+/-0.072 (17loci) and H(e)=0.230+/-0.065 (19loci), respectively. This estimate was somewhat lower in S. nudus, H(e)=0.126+/-0.043 (17loci). Estimates of Nei's genetic distance between S. nudus/S. intermedius (D=1.578, 17loci) and S. nudus/S. pallidus (D=1.327, 15loci) were considerably higher than that between S. intermedius/S. pallidus (D=0.269, 17loci). Invoking the protein clock hypothesis and using Panamanian geminate sea urchins for protein clock calibration, the time of divergence between S. intermedius and S. pallidus was estimated as 2.7MY. The results obtained for S. intermedius and S. nudus by us differ considerably from results obtained for these species by Norimasa Matsuoka and coworkers. The revealed discrepancies are discussed and the conclusion made that Matsuoka and coworkers' data on echinoderm biochemical genetics and systematics should be used with caution.     

Unusual isozyme patterns of glucose-6-phosphate isomerase in polydorids (Polychaeta: Spionidae) and the possible mechanisms of their formation

The isozyme patterns of glucose-6-phosphate isomerase (GPI) have been analyzed in ten species of polychaetes of the genera Polydora and Dipolydora (Polychaeta: Spionidae). The GPI patterns of these species have been found to have some specific characteristics that cannot be explained in terms of the generally accepted views on the nature of isozymes. The patterns are represented by two hybridizing isozymes with different expression specificities that exhibit coordinated allozymic variation in most individuals of each species studied. Involvement of alternative splicing in the expression of the GPI gene is considered to be the most probable mechanism of the formation of the unusual GPI isozyme patterns in polydorids.     

Genetic differences between two allopatric sibling species of the genus Polydora (Polychaeta: Spionidae) from the West Pacific

Polydora vulgaris Mohammad, 1972, a commensal borer of the oysters Pinctada margaritifera and Hyotissa hyotis from the South China Sea, was investigated by means of starch gel electrophoresis. Polydora vulgaris and the allopatric sibling Polydora glycymerica Radashevsky, 1993, a commensal borer of the bivalve Glycymeris yessoensis from the Sea of Japan, were compared with respect to their allozymic variation and number of isozyme loci. Interspecific differences in the number of gene loci coding for three enzymes: alanopine dehydrogenase, glucose-6-phosphate isomerase and -iditol dehydrogenase were revealed suggesting that we are dealing with two valid species. Two different modes of origin duplicate loci in polydorids are dicussed—polyploidization and regional gene duplication. The use of gene number as a character for discriminating between morphologically indistinguishable allopatric polydorid taxa is outlined.