Evidence for the identity of glutathione-dependent formaldehyde dehydrogenase and class III alcohol dehydrogenase

Formaldehyde dehydrogenase (EC 1.2.1.1) is a widely occurring enzyme which catalyzes the oxidation of S-hydroxymethylglutathione, formed from formaldehyde and glutathione, into S-formyglutathione in the presence of NAD. We determined the amino acid sequences for 5 tryptic peptides (containing altogether 57 amino acids) from electrophoretically homogeneous rat liver formaldehyde dehydrogenase and found that they all were exactly homologous to the sequence of rat liver class III alcohol dehydrogenase (ADH-2). Formaldehyde dehydrogenase was found to be able at high pH values to catalyze the NAD-dependent oxidation of long-chain aliphatic alcohols like n-octanol and 12-hydroxydodecanoate but ethanol was used only at very high substrate concentrations and pyrazole was not inhibitory. The amino acid sequence homology and identical structural and kinetic properties indicate that formaldehyde dehydrogenase and the mammalian class III alcohol dehydrogenases are identical enzymes.     

Chloroplast DNA variation inAnemone s. lato (Ranunculaceae)

Chloroplast DNA of seven species belonging toAnemone (sectt.Omalocarpus, Anemonidium, andAnemonanthea),Hepatica, andPulsatilla have been analyzed by restriction enzymes. According to the dendrogram constructed, the sections ofAnemone and the generaHepatica andPulsatilla seem to be evolutionary approximately equidistant to each others. This supports the concept that these groups should be treated on a similar taxonomic level, either as genera or subgenera.     

Excess amino acid polymorphism in mitochondrial DNA: contrasts among genes from Drosophila, mice, and humans

Recent studies of mitochondrial DNA (mtDNA) variation in mammals and Drosophila have shown an excess of amino acid variation within species (replacement polymorphism) relative to the number of silent and replacement differences fixed between species. To examine further this pattern of nonneutral mtDNA evolution, we present sequence data for the ND3 and ND5 genes from 59 lines of Drosophila melanogaster and 29 lines of D. simulans. Of interest are the frequency spectra of silent and replacement polymorphisms, and potential variation among genes and taxa in the departures from neutral expectations. The Drosophila ND3 and ND5 data show no significant excess of replacement polymorphism using the McDonald-Kreitman test. These data are in contrast to significant departures from neutrality for the ND3 gene in mammals and other genes in Drosophila mtDNA (cytochrome b and ATPase 6). Pooled across genes, however, both Drosophila and human mtDNA show very significant excesses of amino acid polymorphism. Silent polymorphisms at ND5 show a significantly higher variance in frequency than replacement polymorphisms, and the latter show a significant skew toward low frequencies (Tajima's D = -1.954). These patterns are interpreted in light of the nearly neutral theory where mildly deleterious amino acid haplotypes are observed as ephemeral variants within species but do not contribute to divergence. The patterns of polymorphism and divergence at charge-altering amino acid sites are presented for the Drosophila ND5 gene to examine the evolution of functionally distinct mutations. Excess charge-altering polymorphism is observed at the carboxyl terminal and excess charge-altering divergence is detected at the amino terminal. While the mildly deleterious model fits as a net effect in the evolution of nonrecombining mitochondrial genomes, these data suggest that opposing evolutionary pressures may act on different regions of mitochondrial genes and genomes.      

The distribution of C-arachidonic acid in hamster lungs is sensitive to quinacrine

Isolated hamster lungs were labelled with ¹⁴C-arachidonic acid. When the lungs were ventillated with a respirator only a small amount of radioactivity was released to the perfusion effluent. This release was not changed significantly by pulmonary infusion of quicacrine (0.5 mM), a known inhibitor of phospholipase A₂. After the perfusion about 75% of the radioactivity in the lungs was in phospholipids, mainly in phosphatidylcholine, phosphatidylethanolamine and phosphatidylinostil and to a lesser degree in phosphatidylserine and phosphatidic acid. About one fourth of the radioactivity was in neutral lipids (tri- and diacylglycerols) and as free unmetabolized ¹⁴C-arachiodonic acid. Pulmonary infusion of quinacrine increased the amount of radioactivity in diacylglycerols and phosphatidylinositol but had no effect on that in phosphatidylcholine, phosphatidylserine, phosphatidic acid and triacylglycerols. The amount of radioactivity in phosphatidylethanolamine was decreased by quinacrine and increased in the vicinity of an unidentified phospholipid-quinacrine complex. The present study indicates that the distribution of ¹⁴C-arachidonic acid in hamster lung lipids is sensitive to quinacrine. The detected changes can, however, not be explained by an overall inhibition of phospholipase A₂ activities.     

Demonstration of PGl2 production by isolated perfused rat lungs with platelet aggregation test

Platelet aggregation test was used for PGl₂ measurements. The use of 6 % CO₂ in air stabilized human platelet rich plasma (PRP) so that it could be used for up to 7 hours in these measurements. The PGl₂ caused inhibition of aggregation in response to ADP was concentration dependent in the range of 0.5 ng/ml to 50 ng/ml. Isolated perfused rat lungs released spontaneously 190 ng/min PGl₂ and about 3 % of infused arachidonic acid potassium salt (equivalent to 25 μg/min arachidonic acid) was converted to PGl₂.     

Integrin CD11c/CD18 α-Chain Phosphorylation Is Functionally Important

CD11c/CD18 (α_Xβ₂, p150/95, or complement receptor 4, CR4) is a monocyte/macrophage-enriched integrin that has been reported to bind to a variety of ligands. These include cell surface proteins, extracellular matrix proteins, and soluble ligands. The regulation of ligand binding to CD11c/CD18 has remained poorly understood. Previous work has shown that both α-chain and β-chain phosphorylations of CD11a/CD18 and CD11b/CD18 are needed for activity, but no corresponding studies on CD11c/CD18 have been performed. In this study, we have identified the phosphorylation site of CD11c as Ser-1158 and show that it is pivotal for adherence and phagocytosis.