Archivos de biologia y medicina experimentales最新文献

To determine the transitions of sea urchin sperm specific non-histone chromosomal proteins (Sp NHCP) following fertilization, their presence in zygotes during and after male pronuclear formation was investigated by comparing the electrophoretic patterns of NHCP obtained from gametes with those isolated from zygotes. Polyclonal antibodies directed against whole Sp NHCP were used to detect, by Western immunoblots, the Sp NHCP among the NHCP present in zygotes at different times post-insemination. The results obtained from immunological and electrophoretic studies indicate that shortly after fertilization the majority of Sp NHCP are lost. The electrophoretic patterns of NHCP obtained from unfertilized eggs were almost identical with those observed for NHCP isolated from zygotes. This similarity strongly suggests that the NHCP of unfertilized eggs are conserved after fertilization.

Acetaldehyde, a product of alcohol metabolism, is known to bind covalently to plasma and red cell proteins, yielding stable adducts which have recently shown are recognized as foreign by the immune system. The present study demonstrates that immunization of mice with protein-acetaldehyde adducts in aluminum hydroxide gel results in the production of reaginic antibodies that recognize the adducts and trigger an allergic-anaphylactic reaction. These findings may lead to new approaches in the treatment of excessive alcohol consumption in humans.

Mammary gland growth and differentiation are largely dependent on a complex and interrelated action of many different hormones which makes the mammary tissue a very suitable one for the study of heterologous hormonal regulation. This type of control is analyzed by two different approaches: 1. The participation of estradiol in prolactin action during lactation, and 2. The role of glucocorticoids and thyroid hormones in the control of functional activity of rat mammary gland beta-adrenergic receptors.

The ability of bacterial strains to metabolize lignin model compounds was studied. Strains examined were non-filamentous bacterial isolates obtained from decaying wood and the actinomycete Streptomyces viridosporus T7A. Model compounds included dimers containing either the beta-1 (1,2-diarylethane) or the beta-O-4 (arylglycerol-beta-aryl ether) type of linkage. Pseudomonas fluorescens biovar I A1 proliferated on anisoin (4,4'-dimethoxybenzoin) accumulating anisic acid temporarily. Cleavage at the beta-1 bond was also observed with crude extracts prepared from the same strain. In turn, cleavage of the beta-O-4 linkage of veratrylglycerol-beta-guaiacyl ether was detected in cultures of Pseudomonas acidovorans D3. In this case, main degradation intermediates were beta-hydroxypropioveratrone, acetoveratrone and guaiacol. S. viridosporus T7A reduced the carbonyl group of some beta-1 dimers and did not modify the beta-O-4 model compounds tested. Attempts to ascribe a catabolic character to large molecular weight extrachromosomal DNA present in some strains were unsuccessful. Gene banks of P. fluorescens biovar I A1 and P. acidovorans D3 were prepared utilizing the broad host range cosmid pLAFR1 as vector.

Recent studies have demonstrated the existence of cortico-nigral fibers in the brain which may use L-glutamic or L-aspartic acid as their transmitters. Such cortico-nigral neuronal pathway seems to functionally interact with intrinsic neuronal systems in substantia nigra (SN) by first activating different subtypes of excitatory amino acid (EAA) receptors. Particularly interesting are results showing that activation of N-methyl-D-aspartate (NMDA) subtype receptor may evoke the Ca(2+)-dependent release of dopamine from dendrites of nigro-striatal neurons. In addition, NMDA and other EAA receptors may influence the functional activity of gabaergic, glycinergic and peptidergic neurons located in SN. Acidic aminoacid-containing neurons in SN may thus play a pivotal role in determining the outflow information from SN to caudal motor-related as well as rostral limbic-related areas in the brain.