Plasma membrane NADH dehydrogenase and Ca2+-dependent potassium transport in erythrocytes of several animal species

Ca²⁺-dependent K⁺ transport and plasma membrane NADH dehydrogenase activities have been studied in several ‘high-K⁺’ (human, rabbit and guinea pig) and ‘low-K⁺’ (dog, cat and sheep) erythrocytes. All the species except sheep showed Ca²⁺-dependent K⁺ transport. NADH-ferricyanide reductase was detected in all the species and showed positive correlation with the flavin contents of the membranes. NADH-cytochrome $\text{c}$ reductase was very low or absent in dog, sheep and guinea pig membranes. No correlation was found between NADH dehydrogenase and Ca²⁺-dependent K⁺ channel activities in the species studied. Nor were any of the above activities correlated with $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ activity.     

Plasma membrane nadh dehydrogenase and Ca2+-dependent potassium transport in erythrocytes of several animal species

Ca2+-dependent K+ transport and plasma membrane NADH dehydrogenase activities have been studied in several 'high-K+' (human, rabbit and guinea pig) and 'low-K+' (dog, cat and sheep) erythrocytes. All the species except sheep showed Ca2+-dependent K+ transport. NADH-ferricyanide reductase was detected in all the species and showed positive correlation with the flavin contents of the membranes. NADH-cytochrome c reductase was very low or absent in dog, sheep and guinea pig membranes. No correlation was found between NADH dehydrogenase and Ca2+-dependent K+ channel activities in the species studied. Nor were any of the above activities correlated with (Na+ + K+)-ATPase activity.     

Trehalose Increases Freeze-Thaw Damage in Liposomes Containing Chloroplast Glycolipids

Chloroplast thylakoids contain three classes of glycolipids, monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and sulfoquinovosyldiacylglycerol (SQDG). We have investigated the stability of large unilamellar vesicles made from egg phosphatidylcholine (EPC) and different chloroplast glycolipids during freezing to -18 degreesC, as a function of the presence of three sugars: glucose, sucrose, or trehalose. Contrary to the situation in thylakoids, where cryoprotection increases from glucose < sucrose < trehalose, liposomes containing 50% DGDG showed the opposite behavior. In fact, carboxyfluorescein leakage increased over the control values (freezing in the absence of sugar) in the presence of trehalose. This effect was not seen in vesicles made from pure EPC, or a mixture of EPC and MGDG, or EPC and SQDG. Liposomes made from mixtures of all three glycolipids, however, showed even more leakage in the presence of trehalose than liposomes containing only DGDG and EPC. Copyright 1998 Academic Press.     

Sodium-Stimulated Glutamate Transport in Osmotically Shocked Cells and Membrane Vesicles of Escherichia coli

Three phenotypically distinct strains of Escherichia coli B were studied: one in which the transport of glutamate was strongly stimulated by sodium, one in which the transport was relatively independent of sodium, and one which did not transport glutamate. Membrane vesicle preparations from the three strains followed the behavior of whole cells with respect to sodium-stimulated transport. Although glutamate-binding material could be released from cells by osmotic shock, its affinity for glutamate was not significantly influenced by sodium. Furthermore, the shocked cells retained sodium-stimulated transport. The accumulated results suggest that the sodium-activated glutamate transport system resides in the cytoplasmic membrane and that releasable binding protein(s) is not intimately involved in its function.     

Long internal inverted repeat in a yeast viral double-stranded RNA.

The Saccharomyces cerevisiae viruses are non-infectious double-stranded (ds) RNA viruses present in most laboratory strains of yeast. Their genome consists of one or more dsRNAs separately encapsidated in particles composed mainly of one polypeptide, which has a Mr of 88 kdaltons in the best-studied viral subtype. A large viral dsRNA (L1, of 4.7 kb) encodes the capsid polypeptide. We have determined the sequences of a number of cDNA clones homologous to portions of L1 and mapped them by a novel heteroduplex technique. Several of these clones originate from a region of L1 2.3-2.5 kb from the 5' end of the plus strand that contains stop codons in all three reading frames in the plus strand. We therefore suspect that the capsid polypeptide gene lies in the 5' 2.3-2.6 kb of the plus strand. One of the cloned cDNAs has an inverted repeat of 170 bp that appears to be present in its parental RNA. The inverted repeat in L1 is the longest known inverted repeat in a viral dsRNA and the only known non-terminal inverted repeat. It might serve the function of creating two mRNAs from one viral dsRNA.     

Loss of Rubella Antibody from Immune Globulin Treated with Kaolin

Sera and immune globulin (IG) preparations are customarily treated with kaolin before titration of their rubella hemagglutination-inhibiting (HI) antibody in order to rid them of nonspecific inhibitors of hemagglutination. The treatment was shown in this investigation to have no adverse effect on the antibody level of the sera but was found to remove considerable amounts of gamma-globulin from IG preparations. Evidence of this removal was obtained by serological tests, by spectrophotometric determination of protein concentration and by disc electrophoresis. In contrast to kaolin, heparin-manganese chloride (MnCl(2)) treatment of IG preparations had essentially no effect on the level of antibody globulin by all the criteria used. Heparin-MnCl(2)-treated IG lots were in these respects similar, if not identical, to their untreated counterparts. Since nonspecific inhibitors associated with the beta-lipoprotein fraction of serum are removed by the method employed to fractionate the IG samples, it seems unnecessary to treat the latter in any way for the HI test. No difficulty was encountered in this investigation with several untreated IG lots.     

Lack of geographic variation in anonymous nuclear polymorphisms in the American oyster, Crassostrea virginica

Comparing geographic variation of noncoding nuclear DNA polymorphisms, which presumably are neutral to natural selection, with geographic variation of allozymes is potentially a good way to detect the effects of selection on allozyme polymorphisms. A previous study of four anonymous nuclear markers in the American oyster, Crassostrea virginica, found dramatic differences in allele frequency between the Gulf of Mexico and the Atlantic Ocean. In contrast, 14 allozyme polymorphisms were fairly uniform in frequency between the two areas. This led to the conclusion that all of the allozyme polymorphisms were kept uniform in frequency by balancing selection. To test the robustness of this pattern, six additional anonymous nuclear DNA polymorphisms were surveyed in oysters from Panacea, Fla, and Charleston, S.C. on the Gulf and Atlantic coasts, respectively. Unlike the previously studied DNA markers, the six DNA polymorphisms examined here show geographic variation that is not significantly greater than that of allozymes. The reason for the discrepancy between the two sets of DNA polymorphisms is unclear.      

Salmonella infantis in Cattle Feedlot Runoff

Ten isolates of Salmonella infantis (serologically typed) were found in litter and runoff collected from two experimental feedlots near the Kansas State University campus. Pathogenic implications are discussed relative to recreation water sites. Agricultural runoff maybe a source of viable salmonellae.