Multiple xylanases of Cellulomona fimi are encoded by distinct genes

Cellulomonas fimi genomic DNA encoding xylanase activity has been cloned and expressed in Escherichia coli. As judged by DNA hybridization and restriction analysis, twelve xylanase-positive clones carried a minimum of four different xylanase (xyn) genes. The encoded enzymes were devoid of cellulase activity but three of the four bound to Avicel.     

Dual action of hydroxylated diphenylethylene estrogens on protein kinase C1

Protein kinase C (PKC) I (gamma), II (beta) and III (alpha) subspecies are all activated by 1,1-di-(p-hydroxyphenyl)ethylene derivatives (DPE) at micromolar concentrations. This PKC activation depends on the presence of both Ca2+ and phosphatidylserine (PS) but does not require diacylglycerol (DG). DPEs enhance PKC activity at low PS concentrations, but not at saturating PS concentrations. Like DG, DPEs increase the apparent affinity of PKC for PS as well as for Ca2+, but lead to a decrease in the catalytic activity (Vmax). In the presence of saturating DG concentrations, DPEs exhibit an inhibitory action. The derivatives also inhibit the activity of the proteolytic fragment of PKC, protein kinase M. It is concluded that DPEs are mixed-type inhibitors, probably interacting with the catalytic domain of the enzyme.     

Certain biochemical characteristics of an insulin-like substance from the bivalve mollusk Anodonta cygnea

An insulin-like substance (ILS) was isolated from the visceral organs of the bivalve mollusc Anodonta cygnea by chromatography on a sulfocationite CU-23 and purified by reverse phase liquid chromatography. ILS was shown to be made up to several fractions with Mr ranging from 9 to 20 kDa which have identical amino acid composition but different hydrophobicity and N-terminal amino acids. It was supposed that the heterogeneity of ILS fractions is due to its genetical or posttranslational polymorphism. ILS has a low (0.02%) affinity for the mammalian insulin receptor and a low immune affinity for mammalian insulin and possesses a mitogenic activity which is commensurate with that of the epidermal growth factor. The data obtained suggest that Anodonta cygnea ILS represents a separate branch of a relatively ancient family of insulin-like hormones and growth factors responsible for metabolism and proliferation of invertebrate tissues.     

A comparative histological and histochemical study of the post-gastric alimentary canal from three species of pleuronectid, the Atlantic halibut, the yellowtail flounder and the winter flounder

The histology and mucus histochemistry of the pleuronectid post-gastric alimentary canal was examined using light and electron microscopy. Distinct differences in goblet cell mucus histochemistry were observed between species, with the two closest taxonomic species, the winter flounder and the yellowtail flounder showing the most diversity and the halibut showing regional variation. Numbers of goblet cells within post-gastric regions did not differ significantly between species, but were significantly different between regions within species increasing toward the rectum. The post-gastric region was divisible into two areas based upon the ultrastructural features of lipid digestion and absorption in the intestine and pyloric caeca, and of exogenous protein in the rectum. The combination of species-specific histochemical differences in mucus and general histological and ultrastructural differences within the post-gastric regions between these species suggest a correlation between lumenal environmental conditions/histology and natural prey preference.     

Novel Interaction of the Z-DNA Binding Domain of Human ADAR1 with the Oncogenic c-Myc Promoter G-Quadruplex

Both G-quadruplex and Z-DNA can be formed in G-rich and repetitive sequences on genome, and their formation and biological functions are controlled by specific proteins. Z-DNA binding proteins, such as human ADAR1, have a highly conserved Z-DNA binding domain having selective affinity to Z-DNA. Here, our study identifies the Z-DNA binding domain of human ADAR1 (hZα_ADAR1) as a novel G-quadruplex binding protein that recognizes c-myc promoter G-quadruplex formed in NHEIII₁ region and represses the gene expression. An electrophoretic migration shift assay shows the binding of hZα_ADAR1 to the intramolecular c-myc promoter G-quadruplex-forming DNA oligomer. To corroborate the binding of hZα_ADAR1 to the G-quadruplex, we conducted CD and NMR chemical shift perturbation analyses. CD results indicate that hZα_ADAR1 stabilizes the parallel-stranded conformation of the c-myc G-quadruplex. The NMR chemical shift perturbation data reveal that the G-quadruplex binding region in hZα_ADAR1 was almost identical with the Z-DNA binding region. Finally, promoter assay and Western blot analysis show that hZα_ADAR1 suppresses the c-myc expression promoted by NHEIII₁ region containing the G-quadruplex-forming sequence. This finding suggests a novel function of Z-DNA binding protein as a regulator of G-quadruplex-mediated gene expression.     

Differential effects of anticytoskeletal compounds on the localization and chemical patterns of actin in germinating conidia of Neurospora crassa

Abstract Anti-actin drugs, cytochalasins A and B, inhibited both normal single, and benomyl-induced multiple, germ tube outgrowth from conidia of Neurospora crassa . Actin was cytochemically found to be concentrated in each of the benomyl-induced germ tube tips. No significant quantitative changes either in total actin or its isoforms were measured in the inhibitor-treated germlings. While intact microtubules are required for normal, monopolar axiation of the germ tube, they appear not to be necessary for benomyl-induced multipolar outgrowth which, in contrast, still requires intact actin microfilaments. Microfilaments and microtubules thus play complementary roles in the normal germination of conidia.