Novel heme-binding component in the serum of the channel catfish (Ictalurus punctatus)

The serum of the channel catfish (Ictalurus punctatus) was examined for heme- and hemoglobin-binding proteins. Electrophoretic mobility retardation assays failed to detect a hemoglobin-binding material similar to mammalian haptoglobin; however, a heme-binding component (not previously described) was identified in catfish seru. The heme-binding component was purified by gel filtration chromatography; electrophoretic analyses suggested it to be composed of two polypeptide subunits of molecular masses about 115 and 98 kDa. This composition is inconsistent with hemopexin, the known heme-binding serum protein of mammals. Although it was not fully saturated with heme, the catfish component contained detectable heme in normal sera. When complexed by the binding material, heme was used as an iron source by isolates of the bacterial Gram-negative genusAeromonas; the capacity of other bacteria to use the complex was not tested. The physiological function of the catfish heme-binding serum protein is presently not clear.     

Developmental and hormonal regulation of specific proteins in mouse vas deferens and seminal vesicle.

This paper is concerned with hormonal regulation of the developmental pattern of major proteins of the mouse vas deferens (mouse vas deferens protein: MVDP, 34.5 kD) and seminal vesicle (15.5, 120 and 140 kD) whose expression is regulated by testosterone at adulthood. The ontogeny of these proteins, studied by SDS-polyacrylamide gel electrophoresis, appeared to be uncoordinated. MVDP was not accumulated until animals were 20 days old and its concentration increased sharply from 20 to 30 days of age. In seminal vesicle, the 15.5 kD protein did not accumulate before day 30 whereas 120 and 140 kD proteins appeared and accumulated between 30 and 40 days. In 30-day-old mice castrated at birth or treated with cyproterone acetate over 29 days, MVDP levels were not abolished and were similar to those measured in 20-day-old males. Testosterone administration, from 1 to 10 days of age, did not induce precocious expression of MVDP. These results suggest that the neonatal expression of MVDP is independent of androgens. In seminal vesicle, the first expression of the 3 proteins studied was dependent upon testicular androgens as shown by neonatal castration and injection experiments. The marked increase in the levels of the 4 proteins studied, during sexual maturation, was not associated with quantitative or qualitative changes in tissular androgen concentrations, suggesting that other factors may be necessary for protein expression. Whereas thyroxine may induce a precocious accumulation of MVDP, prolactin had no stimulatory effect on the accumulation of proteins from vas deferens and seminal vesicle. The results suggest that during sexual maturation gene activation by androgens was progressive.     

Structures of the α(1-3)-galactose-containing asparagine-linked glycans of a Lewis lung carcinoma cell subline resistant toAleuria aurantia agglutinin: elucidation by1H-NMR spectroscopy

Four bi-antennary glycan fractions of theN-acetyllactosamine-type, derived from a Lewis lung carcinoma (LL₂) cell subline resistant to theAleuria aurantia agglutinin were studied by 400 MHz¹H-NMR spectroscopy. By this method, their antennae were found to be terminated either by (2-3 or 6)-linkedN-acetylneuraminic acid or (1-3)-linked galactose residues. The primary structure of glycans of these four glycopeptide or derived oligosaccharide-alditols has been determined in full detail.Abbreviations NAc N-acetyl group - NGc N-glycolyl group - GlcNAc N-acetylglucosamine - NeuAc N-acetylneuraminic acid - NeuGc N-glycolylneuraminic acid - Man mannose - Gal galactose - Fuc fucose - Con A concanavalin A - LCA Lens culinaris agglutinin - AAA Aleuria aurantia agglutinin - WGA Wheat germ agglutinin - RCA II Ricinus communis agglutinin II - PBS phosphate buffered saline, 0.01m Na₂HPO₄/0.14m NaCl, pH 7.2 - HPLC high performance liquid chromatography - EMEM Eagle's Minimal Essential Medium - Lec^R lectin resistant - MG -methylglycoside     

Characterization of a developmentally transient adrenergic depolarizing response in cultured locus coeruleus neurons

The effects of iontophoretically applied noradrenaline have been tested on intracellularly recorded locus coeruleus neurons grown in explant cultures from neonatal mice. In addition to hyperpolarizing responses mediated by alpha 2-adrenergic receptors, as observed in locus coeruleus neurons in vivo and in brain slices from adult animals, alpha 1-mediated depolarizations were observed to succeed the initial hyperpolarizations in some cultures. It was shown that the depolarizing responses were only present in younger cultures, i.e., less than 26 days in vitro. In cultures less than 20 days old, all cells displayed the biphasic hyperpolarizing-depolarizing responses. Both components of the response appear to be direct, since they were present when synaptic transmission was blocked by including tetrodotoxin or by altering divalent cations in the perfusate. The depolarizing responses were frequently reduced in solutions with altered divalent cation content, and this might reflect a calcium dependency of this response. The hyperpolarizing and depolarizing components of the responses to noradrenaline were progressively blocked by increasing concentrations of the selective antagonists yohimbine and prazosin, respectively, in the dose ranges of 100 mM - 1 microM (yohimbine) and 20-200 nM (prazosin). Recent results from electrophysiological studies of locus coeruleus neurons in brain slices suggest that similar changes occur in the animal as well as in culture. It is possible that the transient depolarizing responses reflect a developmentally important enhanced responsiveness of locus coeruleus neurons during the early postnatal period.     

Stereoscopic back-scattered electron imaging of silver-stained proteins in nucleoli

By using simultaneously the AgNOR silver staining method, back-scattered electron imaging mode and stereo-tilt in scanning electron microscopy (SEM), it is possible to observe the nucleus through the cell surface, the nucleolus, and the tri-dimensional distribution of the AgNOR-associated acidic proteins. In C3H10T1:2 cells and their 7-12-dimethylbenz--anthracene-treated transformants, the staining demonstrates several intranucleolar silver-staining granules (SSG), surrounded by a weakly staining region. The SSG may represent the fibrillar center (FC) and the weakly staining region, the fibrillar dense component (FD). This component can link several SSG together to form a rope-like structure. In cells with no visible nucleolus and inactive nucleolar organizer regions (NORs) the silver-staining granules are less numerous, close together and the presumed fibrillar dense components are not visible. The SSG are located more peripheraly, and the weakly staining region and the rope-like structure are less prominent in control cell nucleoli than in transformed cells with a comparatively high rate of RNA synthesis.     

Some aspects of the natural history and food selection ofAvahi laniger

Two groups ofAvahi laniger were studied in the Forêt de Analamozoatra near Perinet in the eastern rainforest of Madagascar from August to October 1984. Overlap between the home ranges of neighbouring groups ofA. laniger was minimal. Group size ranged from one to four individuals with a median group size of two. In four out of ten groups a baby was born between August and September.A. laniger were most active after dusk and before dawn. They had an extended resting period around midnight. Their diet consisted mostly of leaves from at least 17 different plant species. They also ate flowers. Fruit eating was recorded twice. Leaves eaten had high contents of protein and sugar but did not contain alkaloids. The concentration of condensed tannins did not differ between food items and non-food items. There was no indication of competition with other prosimians that might explain their nocturnality.     

Use of purified antipeptide sera of selected specificity for the detection of the simian virus 40 large T antigen by western blotting

Western blotting was used as a powerful alternative to immunoprecipitation for the detection of the simian virus 40 (SV40) large tumor (T) antigen. After resolution by electrophoresis on a SDS-polyacrylamide gel of a [¹⁵S]methionine labeled crude extract from SV40 infected monkey kidney cells, the separated proteins were transferred electrophoretically on nitrocellulose paper. T antigen was detected on nitrocellulose strips by using for the first time, specific, purified antipeptide monoclonal antibodies directed against the N- and C-terminal portions of the molecule, and¹²⁵I-labeled Protein A.     

Morphogenic substances released by plant tissue cultures

The release of endogenous substances is a general phenomenon of plant tissue cultures, with some substances having significant developmental effects on the releasing tissues. Their systematic study was initiated with Nandina tissue cultures, and a yellow compound that accumulated in the culture medium was identified as the alkaloid, berberine. The rate of its release was related to the supplies of auxin, cytokinin, and nutrient salts. Addition of berberine \ HCl to nutrient media did not inhibit Nandina tissues, but suppressed shoot formation in Nicotiana stem segments. Growth of Nandina and Nicotiana callus, as well as rooting of Nicotiana stem segments, was promoted by alkaloid addenda.