[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.

[Linkage of genes responsible for sex determination and expression of a sperm-specific isozyme of glucose-6-phosphate isomerase in the polychaete Polydora brevipalpa]. / Stseplenie genov, otvetstvennykh za opredelenie pola i ékspressiiu spermii-spetsificheskogo izofermenta gliukozo-6-fosfatizomerazy, u polikhety Polydora brevipalpa.

In Polydora brevipalpa (Polychaeta, Spionidae), an unusual electrophoretic pattern of glucose-6-phosphate isomerase (GPI) which is determined by a single GPI gene locus and represented by two isozymes (GPI-1 and GPI-2) has been revealed. The anode isozyme (GPI-1) was detected in both males and females, whereas the cathode enzyme GPI-2 appears in males and results from alternative splicing of the pre-mRNA transcripts. In males, GPI-2 was shown to express only in sperm. The results obtained suggest that the genes responsible for sex determination and expression of the alternative isozyme GPI-2 are tightly linked. However, rare recombination events between these genes produce reciprocal deviant GPI phenotypes in males (GPI-2 is absent) and females (GPI-2 is present). In the sample of 376 individuals (202 males and 174 females) six recombinant males and six recombinant females were found, which ratio is in good agreement with the expected 1:1 ratio. Recombinant males of different genotypes at the GPI locus were also found. This indicates the absence of negative selection against all genotypes of the locus, except those carrying the unique allele that controls the cathode allozyme GPI-1. The results obtained suggest genetic sex determination in P. brevipalpa. Based on the fact that genetic sex determination is also characteristic of other species of the genus Polydora, which diverged independently during several million years, and taking into account that only six recombination events occurred in the history of 376 P. brevipalpa genomes examined, the conclusion is made that the gene responsible for sex determination and that responsible for the expression of the alternative GPI-2 isozyme are tightly linked.

Nonfluorescent negative stain for alanopine dehydrogenase activity on starch gels.

A two-step procedure for negative staining NADH-dependent alanopine dehydrogenase (ALPDH) activity on starch gels is described, using nitroblue tetrasolium and phenasine methosulfate. This method gives a blue background with unreacted NADH, and white areas where ALPDH is located. Using this technique the first reliable evidence of the existence of true ALPDH isoenzymes is obtained.

[Purification and some properties of electrophoretic variants of 6-phosphogluconate dehydrogenase from rat erythrocytes]. / Ochistka i nekotorye svoistva elektroforeticheskikh variantov 6-fosfogliukonatdegidrogenazy iz eritrotsitov krysy

Purification procedure of electrophoretic variants FF and SS of 6-phosphogluconate dehydrogenase (6-PGD) is described. The method includes (NH4)2SO4 fractionation and chromatography on DEAE- and CM-celluloses. Isoenzymes were purified about 5000 fold, and were found to be homogenous by disc electrophoresis in 7% polyacrylamide gel. It was found by comparative studies of activities of variants FF and SS, that pH optimum was 8.2 for variant FF and 8.8 for variant SS. Km for 6-phosphogluconate were found to be 17,5-10(-5) M for variants SS and FF respectively.