Immunohistochemical localization of vitamin D-dependent calcium-binding protein in duodenum,kidney, uterus and cerebellum of chickens

Summary Calcium-binding protein (CaBP) has been localized with the immunoperoxidase method using antiserum against purified chick duodenal CaBP. Different preparative procedures were employed to investigate the experimental conditions possibly responsible for the contradictory reports in the literature of the precise cellular localization of CaBP. Freeze substitution, frozen sections followed by fixation and coagulant and non-coagulant fixatives were used with appropriate control sections to demonstrate that the true localization of CaBP in the chick duodenum is in the absorptive cell cytoplasm. The goblet cell localization reported in the literature seems to be a diffusion artifact due to inadequate fixation. CaBP was also localized in several other tissues. In the hen uterus, the tubular glands beneath the surface epithelium showed intense reaction. In the kidney, CaBP was present in the cells of the straight and convoluted segments of distal tubules. The cortex of the chick cerebellum showed the CaBP in Purkinje cells. The entire dendritic trees contained the reaction product. No other neurons in the molecular or the granular layer were stained. In the deep cerebellar nuclei, all neurons were negative and these were outlined by deeply staining axons of the Purkinje cells and their synaptic endings.     

Prostaglandin E1 effects on resting and cholinergically stimulated lower esophageal sphincter pressure in cats

Intraluminal esophageal manometry with a sleeve catheter was used to compare the magnitude of decrease in lower esophageal spincter (LES) pressure produced by an arterial or venous infusion of prostaglandin E₁ in cats. Arterial PGE₁ produced significantly lower LES pressures than venous PGE₁ (p < 0.05). Maximal decrease of 75% in basal LES pressure occurred with an associated 15% decrease in systolic blood pressure. The site of action of PGE₁ in producing LES hypotension was studied by injection of either edrophonium, or bethanechol during the maximal PGE₁ effects. Bethanechol, which acts directly on sphincteric smooth muscle, produced an increase in LES pressure during both saline and PGE₁ infusion, while the increases in LES pressure seen with edrophonium during saline infusion were blocked during the PGE₁ infusion. From these studies, we conclude that PGE₁ produces LES hypotension in the cat by an inhibitory effect on the cholinergic pathway responsible for maintaining LES tone. These studies pharmacologically reproduce the LES pressure abnormality previously reported in the cat during acid-induced esophagitis and support the hypothesis that PGE₁ may be involved in the pathogenesis of acute acid-induced lower esophageal sphincter abnormalities.     

A subunit-sized butyrylcholinesterase present in high concentrations in pooled rabbit serum

A butyrylcholinesterase of mol.wt. approx. 83000 was observed in pooled rabbit serum. The enzyme was named monomeric butyrylcholinesterase to distinguish it from the larger oligomeric butyrylcholinesterase of horse and human serum whose subunits are the same size as the monomeric enzyme. The active-site concentration of monomeric butyrylcholinesterase in the pooled serum was 0.18mum, which is five times the concentration of butyrylcholinesterase in pooled horse serum. This was surprising, since the horse serum is regarded as a rich source of butyrylcholinesterase, whereas rabbit serum is not generally thought to contain significant amounts of any butyrylcholinesterase. The explanation, in large part, was the relatively low k(cat.) of the monomeric enzyme, which was approx. 57s(-1) with butyrylthiocholine as substrate and is one-thirtieth of the comparable k(cat.) of horse butyrylcholinesterase. The substrate specificity of monomeric butyrylcholinesterase also differed significantly from that of horse and human butyrylcholinesterase. For example, with the monomeric enzyme, the hydrolysis of 1mm-acetylthiocholine was only 4% the rate for 1mm-butyrylthiocholine, whereas human and horse butyrylcholinesterases hydrolysed 1mm-acetylthiocholine at 50% of the rate for 1mm-butyrylthiocholine. Moreover, monomeric butyrylcholinesterase generally hydrolysed aromatic esters more rapidly than choline esters, whereas the reverse is true of the butyrylcholinesterases. To facilitate the study of monomeric butyrylcholinesterase, it was separated from the larger butyrylcholinesterase and acetylcholinesterase, also present in rabbit serum, and purified 89-fold by fractionation with (NH(4))(2)SO(4) and ion-exchange chromatography.     

Oögenesis in a marine teleost,Blennius pholis L.

Summary Oögenesis in the oviparous marine teleost, Blennius pholis L., is examined. Eleven developmental stages are identified by ultrastructural observations when changes in the distributions of the organelles and inclusions are described. An exogenous source for the protein yolk precursors is indicated, but less clear is the endogenous contribution. Changes in the follicle epithelium are described together with the formation of the zona which is considered to be follicular in origin. Two types of follicle cell are distinguished and these probably function differently in the process of zona formation. The zona becomes divided into the externa and interna, the latter probably resulting from the chemical ordering by disulphide bonding of the proteinaceous material of the former.We are indebted to Professor E.W. Knight-Jones in whose department the work was carried out, and to the Natural Environment Research Council for support for one of us (S.E.S.).     

Quercetin inhibits hexose transport in a human diploid fibroblast

Summary The flavonol quercetin, a phloretin analog, inhibits transport of 2-deoxyglucose and 3-O-methylglucose in a cultured human diploid fibroblast. This inhibition is related to transport itself and not to the reported effects of flavonoids on membrane-bound ATPases. From concentration-inhibition curves at several pH's we conclude that uncharged (acid) quercetin (pK=7.65) is the inhibitory form of the molecule (K _I =10m). Quercetin, unlike phloretin, is rapidly degraded in 0.1n NaOH; the degradation products are weakly inhibitory to hexose transport.     

Purification and properties of mammalian toxins from the venom of the Brazilian scorpion Tityus serrulatus Lutz and Mello

The water-soluble part of the dried venom from the scorpion, Tityus serrulatus Lutz and Mello (range, Southeastern Brazil), showed 16 polypeptide bands on polyacrylamide gel electrophoresis. This material exhibited toxic and hyaluronidase activity but no phospholipase, phosphodiesterase, protease, or fibrinolytic activity. Fractionation on glycinamide-treated Sephadex G-50 afforded three protein fractions, which were non-toxic, equitoxic, and three times more toxic than the water-soluble venom. Subsequent separation of the toxic fractions on carboxymethyl-cellulose with phosphate buffers furnished five toxic components, which were further purified on carboxymethyl-cellulose with a salt gradient in acetate buffer. Toxin γ, the major and most basic toxin, is a 62-residue protein that, unlike other scorpion toxins, contains methionine. Automated Edman degradation showed the amino-terminal sequence to be H-Lys-Glu-Gly-Tyr-Leu-Met-Asp-His-Glu-Gly-Cys-Lys-Leu-Ser-Cys-Phe-Ile-Arg-Pro-Ser-Gly-Tyr-Cys-Gly-Arg-Glu-Cys-Gly-Ile-. Toxin γ is the first example of a fifth structural type of mammalian toxin from scorpion venom. Its amino-terminal sequence shows greater homology with toxins similar to Centruroides suffusus suffusus toxin III and Androctonus australis toxin II than with toxins similar to A. australis toxin I or Bhutus occitanus tunetanus toxin I.     

SMITHSONIELLA GEN. NOV., A POSSIBLE EVOLUTIONARY LINK BETWEEN THE MULTICELLULAR AND SIPHONOUS HABITS IN THE ULVOPHYCEAE,CHLOROPHYTA

A low relief, green turf-forming alga of a heterotrichous habit was discovered in the coral reef microcosm, Museum of Natural History, Smithsonian Institution. Erect filaments bore lateral, specialized sporangia and together with basal filaments possessed septal plugs between adjacent cells, grossly similar to the “pit connections” of red algae. Data are presented which: 1) establish the identity of our plant with a plant recently described as Pilinia earleae Gallagher et Humm from the Florida Gulf coast; 2) support our establishment of the new genus Smithsoniella and our transfer of P. earleae to this new taxon. Additional data on pigmentation and cytology are related to the fine structure of other selected green algae to develop and test three hypotheses, viz. Smithsoniella earleae represents either: 1) a symbiotic association between a green and a red alga; 2) an alga which belongs to either the Ulotrichales, Chaetophorales or the Chroolepidales; or 3) an alga representing an evolutionary link between filamentous forms of the Ulvophyceae and members of the coenocytic siphonalean complex (e.g., Codiales or Caulerpales) of the Chlorophyta. Data refute hypotheses 1 and 2 but do lend support to the third hypothesis.     

Effect of hyperinsulinemia on acid cholesterol ester hydrolase activity in liver, heart and epididymal fat pad preparations from rats and mice

The effect of insulin on lysosomal acid cholesterol ester hydrolase activity was studied in liver, heart and fat pad preparations from rats and mice. Hyperinsulinemia was induced for a period of 6 days in rats by the subcutaneous administration of exogenous insulin by an osmotic minipump. The effect of more chronic endogenous hyperinsulinemia was studied using genetic strains of diabetic (db/db) mice at 12 weeks of age. Mouse liver and heart preparations were characterized as having an acid pH optimum of 4.5-5 for cholesterol ester hydrolase activity; a smaller but distinct pH optimum could also be observed at pH 7. In contrast, hydrolase activity in mouse fat pad preparations had only one distinct pH optimum of 6.5. Hyperinsulinemia in rats and mice resulted in a significant decrease in acid cholesterol ester hydrolase activity in heart preparations, but had no consistent effect on acid hydrolase activity observed in liver and fat pad preparations. This decrease in lysosomal acid cholesterol ester hydrolase activity in cardiac tissue due to hyperinsulinemia cannot be related to any changes in lipoprotein turnover caused by insulin or diabetes.