Phosphoglucose isomerase isozymes in teleostean fishes from the Arabian Gulf

Two phosphoglucose isomerases (PGI) with different electrophoretic mobilities have been found in all groups of teleostean fishes studied, with the exception of the Clupeomorpha. PGI proved to be a good taxonomic criterion to differentiate members of the Nemipteridae, Sciaenidae, Platycephalidae and Stromateidae from the other teleost families.     

Genetic variation and divergence of the sibling pair of cyprinid fishes, Notropis cornutus and N. chrysocephalus

Horizontal starch gel electrophoresis was used to estimate the amount of genetic divergence between Notropis cornutus and N. chrysocephalus. Measures of genetic identity (1) and distance (D) were 0.881 and 0.127 ± 0.055 (s.e.), respectively. These estimates correspond more closely to the sibling species status of these taxa than other previously reported estimates. Notropis cornutus was found to be significantly more variable than N. chrysocephalus electrophoretically and morphologically. Assuming the existence of an electrophoretic clock, the time of divergence was calculated to be roughly 1.9–2.5 million years. This estimate corresponds very closely to a previously hypothesized late Pliocene divergence.     

Role of actin binding protein phosphorylation in platelet cytoskeleton assembly

Actin binding protein from human blood platelets is shown to exist in the resting platelet as a phosphorylated protein and contains two residues of phosphate per 260,000 kd. Removal of one-half of these residues with E. coli alkaline phosphatase results in the loss of its ability to crosslink F-actin into a low speed sedimentable complex (its cytoskeleton) and to bind to an F-actin affinity column. Thus, phosphorylation-dephosphorylation of ABP may be an important regulatory mechanism by which the platelet regulates its shape via its cytoskeletal structure.     

Susceptibility of platelet alpha-actinin to a Ca2+-activated neutral protease

Purified alpha-actinin from human platelets was digested with Ca2+-activated protease from muscle. The alpha subunit (Mr = 100 kDa) was degraded into a unique polypeptide b of slightly lower molecular mass. In fresh platelets, only the a subunit was detected by immunoblotting techniques, while in out-dated platelets, both a and b polypeptides were present. Since a similar conversion of a to b occurs in vitro as in whole platelets, it can be assumed that, in platelets, alpha-actinin is cleaved by the endogenous Ca2+-activated protease.     

Catechol-O-methyltransferase: A method for autoradiographic visualization of isozymes in Cellogel

An electrophoretic procedure for separating the molecular forms of catechol-O-methyltransferase in cellulose acetate gel is described; the zones of enzyme activity were revealed by autoradiography. The electrophoretic patterns of the enzyme in several tissues and cell lines derived from four different species are presented.This investigation was supported by Grant 500.6/Ric. 70/1981 from the Italian Ministry of Health and by the Italian Ministry of Education. We are grateful to Dr. M. Castagnola for useful advice and help with thin-layer chromatography.     

Genetic structure of natural populations of the red-spotted newt,Notophthalmus viridescens

Genetic variation is described at 15 loci in 2 neotenic and 12 nonneotenic populations of red-spotted newts. Though high levels of genetic similarity (I=0.990) were found among all populations, allele frequencies at six of the eight most polymorphic loci show significant heterogeneity across populations. Change in allele frequencies at two of these loci (Pep-2 and Ldh-1) is significantly correlated with latitude. Interspecific homologies are established for newt peptidases based on substrate specificities and lactate dehydrogenases based on tissue distribution, thermal stability, and kinetic properties. Nonneotenic populations are highly variable (H=0.157) and neotenic populations are only slightly, but significantly, less variable (H=0.120). The high levels of heterozygosity detected in nonneotenic populations may result from large effective population size and/or environmental heterogeneity. The unexpectedly high heterozygosity values obtained for the neotenic populations may indicate adult dispersal or the presence of some previously undetected red efts at these localities. In any case, a major change in life history has apparently had little effect on the genetic structure of these populations.This research was supported by grants from the Blakeslee Fund of Smith College.     

Activation and alteration of plant and fungal polyphenoloxidase isoenzymes in sodium dodecylsulfate electrophoresis

Electrophoretic analysis of polyphenoloxidase isoenzymes from a variety of angiosperms and from mushroom revealed that the enzymes remain active in the presence of 0.1 % sodium dodecylsulfate. Electrophoresis in the presence of sodium dodecylsulfate allows the detection of latent enzyme forms of polyphenoloxidase, and can also convert slower migrating enzyme forms to faster migrating forms. Electrophoresis in the absence of sodium dodecylsulfate followed by incubation in the presence of sodium dodecylsulfate can also be used to detect latent forms of polyphenoloxidase. Together, these approaches provide a method for screening latent enzymes and give some insight into the mechanism of activation by sodium dodecylsulfate.     

Murine “housekeeping” enzyme (genetic locus:Idh-1) is regulated in an allele-specific manner

The murine “housekeeping” enzyme, cytosolic NADP-isocitrate dehydrogenase (E.C. 1.1.1.42) (genetic locus:Idh-1), exhibited a complex pattern of allele-specific expression. Protein electrophoresis on cellulose-acetate gels and determination of relative enzymatic activity by means of densitometry revealed that in heart tissue (but not liver tissue) of certain hybrid crosses the AA-homodimer was underrepresented relative to total enzymatic activity, and the degree of underrepresentation changed during development. In mixtures of homozygous tissue extracts of heart tissue (but not liver tissue) the AA-homodimer was underrepresented relative to the BB-homodimer. Relative activity of allelic isozymes varied as a function of tissue (heart versus liver), age, and the parental source of the Idh-1^a allele, but did not vary as a function of sex. Allele-specific expression was also exhibited in kidney tissue of the same animals. In adult male kidney tissue extracts from heterozygotes, the AA-hornodimer was underrepresented relative to total enzymatic activity; in adult female kidney tissue extracts from heterozygotes, a more codominant phenotype was observed. Tissue extracts from immature hybrid animals exhibited a phenotype midway between the adult male and adult female phenotypes. Tissue extracts from castrated males exhibited a phenotype equivalent to that seen in females. Relative activity of allelic isozymes in kidney varied as a function of age and sex, but did not vary as a function of the parental source of the Idh-1^a allele. While cytosolic NADP-IDH is a “housekeeping” enzyme, expressed in multiple tissues of the mouse, differences in the relative intensities of allelic isozyme bands provide evidence for tissue- and stage-specific regulatory variation.     

Phylogenetic relationships in theSideritis leucantha group (Lamiaceae)

Six closely related taxa of the sect.Eusideritis of the genusSideritis (S. leucantha, S. pusilla, S. flavovirens, S. granatensis, S. biflora andS. osteoxylla) are analysed to elucidate their phylogenetic relationships and position within the sect.Eusideritis. Meiotic behaviour, karyotype features, size and fertility of pollen grains, DNA amounts and seed protein profiles are reviewed. A polyploid origin of the group (from x = 7) and the further diversification through dysploidy and chromosome repatterning is postulated.S. osteoxylla is apparently of hybrid origin.     

Qualitative and quantitative changes in hemolymph proteins during an ovarian cycle and after insemination in Thermobia domestica (packard) (thysanura,lepismatidae)

Qualitative and quantitative investigations on the hemolymph proteins in the adult firebrat Thermobia domestica were performed during an ovarian cycle in inseminated and noninseminated females. Variations of hemolymph protein concentration were determined by Lowry's method. In addition, the proteins were studied by gradient slab gel electrophoresis using nondenaturing conditions and microdensitometry. Besides five major protein fractions, which are present in both sexes, three female-specific protein bands (vitellogenins) are found in the hemolymph and in maturing oocytes. These vitellogenins have molecular masses of 430, 300 and 240 kiloDalton. In fact, associated with the main 300-kD band, there were two smaller bands (320 and 280 kD) indistinguishable by densitometric measurement. Quantitative changes of vitellogenins are linked to oocyte maturation. These proteins appeared in the hemolymph before ecdysis, at the same time as the first yolk granules in the basal oocytes. They increased after ecdysis during the intense vitellogenic phase and decreased during chorion formation. In noninseminated females, in which all maturing oocytes are resorbed before chorion formation, the level of the 300 kD vitellogenins remained lower than in inseminated females. The quantity of vitellogenins fell only after complete oosorption. Thus insemination caused changes in the relative quantities of the different vitellogenic proteins.