Inhibition of ovulation, steroidogenesis and collagenolytic activity in rabbits by sulpiride-induced hyperprolactinaemia

Ovulation induced by hCG in rabbits was reduced significantly (P less than 0.005) by sulpiride-induced hyperprolactinaemia. The pre- and post-ovulatory increases in peripheral and ovarian venous progesterone (but not oestradiol or testosterone) were suppressed in the treated animals. The condition of hyperprolactinaemia also prevented the usual changes in 2,4-dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg-OH peptidase (DNP-peptidase) and alpha-N-benzoyl-DL-Arg-beta-naphthylamide hydrolase (BANA-hydrolase) activities in follicular tissue that had been stimulated by an ovulatory dose of hCG. These results suggest that inhibition of progesterone production and collagenolytic enzyme activity by sulpiride-induced hyperprolactinaemia may be responsible for the ovulatory dysfunction that occurs when a mammal has a high level of circulating prolactin.     

Superoxide dismutase is preferentially degraded by a proteolytic system from red blood cells following oxidative modification by hydrogen peroxide

The cupro-zinc enzyme superoxide dismutase (SOD) undergoes an irreversible (oxidative) inactivation when exposed to its product, hydrogen peroxide (H2O2). Recent studies have shown that several oxidatively modified proteins (e.g., hemoglobin, albumin, catalase, etc.) are preferentially degraded by a novel proteolytic pathway in the red blood cell. We report that bovine SOD is oxidatively inactivated by exposure to H2O2, and that the inactivated enzyme is selectively degraded by proteolytic enzymes in cell-free extracts of bovine erythrocytes. For example, 95% inactivation of SOD by 1.5 mM H2O2 was accompanied by a 106 fold increase in the proteolytic susceptibility of the enzyme during (a subsequent) incubation with red cell extract. Both SOD inactivation and proteolytic susceptibility increased with H2O2 concentration and/or time of exposure to H2O2. Pre-incubation of red cell extracts with metal chelators, serine reagents, or sulfhydryl reagents inhibited the (subsequent) preferential degradation of H2O2-modified SOD. Furthermore, a slight inhibition of degradation was observed with the addition of ATP. We suggest that H2O2-inactivated SOD is recognized and preferentially degraded by the same. ATP-independent, metallo- serine- and sulfhydryl- proteinase pathway which degrades other oxidatively denatured red cell proteins. Related work in this laboratory suggests that this novel proteolytic pathway may actually consist of a 700 kDa enzyme complex of proteolytic activities. Mature red cells have no capacity for de novo protein synthesis but do have extremely high concentrations of SOD. Red cell SOD generates (and is, therefore, exposed to) H2O2 on a continuous basis, by dismutation of superoxide (from hemoglobin autooxidation and the interaction of hemoglobin with numerous xenobiotics).(ABSTRACT TRUNCATED AT 250 WORDS)     

Diploid and triploid offspring of triploid agamosporous fernDryopteris pacifica

A cytological and reproductive study of the diploid and triploid agamosporousDryopteris pacifica was made to elucidate the origin of its infraspecific cytotypes. Some triploids produced 16 spore mother cells (SMCs) sometimes with n=41II+41I chromosomes, in addition to eight SMCs with n=123II, in each sporangium. In the former case the 16 SMCs usually underwent abnormal meiosis to give rise to some 50 spores, some of which were regular-shaped; in the latter the eight SMCs multiplied into 32 spores by normal meiosis. We found that spores from one of the triploid plants developed into either diploid or triploid gametophytes, which further apogamously produced diploid or triploid sporophytes, respectively. This novel mechanism of ploidy reduction is discussed in relation to the origin of diploid agamosporous ferns, the taxonomic complexity of the species, and the correlation of agamospory with polyploidy. The mechanism is also compared to that operating in agamospermous angiosperms.     

Performance of 133 compounds in the lambda prophage induction endpoint of the Microscreen assay and a comparison with S. typhimurium mutagenicity and rodent carcinogenicity assays.

The Microscreen assay was developed as a means of testing very small samples, as in complex mixture fractionation. It is a multi-endpoint assay which utilizes E. coli WP2s(lambda). Exposure takes place to serial dilutions of the test compound in microtitre wells (250 microliters) followed by sampling from wells in which growth has occurred ('non-toxic wells'). Although a number of different endpoints can be measured, only the prophage induction endpoint (the first one developed) has been extensively tested. Results with 133 compounds are presented. These include 111 compounds which have been tested in the S. typhimurium assay and 66 compounds for which both rodent bioassay and S. typhimurium assay data exists. The concordance for the Microscreen assay and the S. typhimurium assay was 71%. For this group of compounds, the sensitivity of the Microscreen assay in detecting carcinogens was 76% compared with 58% for the S. typhimurium assay. However, the S. typhimurium assay was somewhat more specific (69%) compared with the Microscreen (56%). The overall association between carcinogenicity and Microscreen results was statistically significant (p = 0.029), whereas for the S. typhimurium assay the association with carcinogenicity was non-significant (p = 0.086). The Microscreen assay was able to detect halogenated compounds better than the S. typhimurium assay. The Microscreen assay should prove useful in complex mixture fractionation, or in other situations where sample size is limiting.     

Isolation and characterization of a cDNA clone encoding the anti-viral protein from Phytolacca americana

Phytolacca anti-viral protein (PAP) was purified from Phytolacca leaves and the N-terminal was sequenced. A cDNA library was made from mRNAs isolated from Phytolacca leaves and cDNA clones for PAP were identified using oligonucleotide probes derived from the N-terminal amino acid sequence. The PAP-cDNA clone was sequenced from both directions. The predicted amino acid sequence of PAP was compared with the amino acid sequences of other ribosome-inactivating proteins. The identities of these proteins to PAP ranged from 29 to 38%, and a region was found in each with a sequence similar to the PAP sequence (AIQMVSEAARFKYI). Southern blot analysis indicates that PAP is encoded by a multi-gene family.Abbreviations MAP Mirabilis jalapa anti-viral protein - PAP Phytolacca anti-viral protein - SO6 30 kDa ribosome-inactivating protein from the seeds of Saponaria officinalis     

Production of cellulolytic enzymes from theXylaria andHypoxylon species of xylariaceae

Eighteen strains of xylariaceous fungi have been screened for higher activities of cellulolytic enzymes,Trichoderma reesei QM 9414 was also examined for comparison. Strains ofXylaria anisopleura andX. regalis had higher endocellulase (CMCase) and exocellulase (Avicelase) activities after 2 weeks' incubation.Hypoxylon stygium produced the highest activity of -glucosidase 3 days after inoculation. The optimum pH for these cellulolytic enzymes was approx. 5.0 and the optimum temperatures ranged from 37 to 50°C. A mixed culture process usingT. reesei QM 9414 andH. stygium was developed to obtain enhanced synthesis of cellulase. -Glucosidase activities in the mixed culture increased within 48h whenH. stygium was introduced after 24h.     

Construction and expression of nonsense suppressor tRNAs which function in plant cells

An Arabidopsis thaliana L. DNA containing the tRNA(TrpUGG) gene was isolated and altered to encode the amber suppressor tRNA(TrpUAG) or the ochre suppressor tRNA(TrpUAA). These DNAs were electroporated into carrot protoplasts and tRNA expression was demonstrated by the translational suppression of amber and ochre nonsense mutations in the chloramphenicol acetyltransferase (CAT) reporter gene. DNAs encoding tRNA(TrpUAG) and tRNA(TrpUAA) nonsense suppressor tRNAs caused suppression of their cognate nonsense codons in CAT mRNAs, with the tRNA(TrpUAG) gene exhibiting the greater suppression under optimal conditions for expression of CAT. The development of these translational suppressors which function in plant cells facilitates the study of plant tRNA gene expression and will make possible the manipulation of plant protein structure and function.     

生态因子对中药甘草质量影响的初步研究

甘草是一种常用中药,由于具有“调和诸药”之功效而成为方剂中最常用的一味药。古有“十方九草”之说,可见对甘草的需求量之大;目前,对甘草的需求不仅仅限于医药界,在食品、轻工、畜牧等行业也有广泛的应用。然而,由于长期滥采、滥挖,只挖不种,使得甘草的蕴藏量急剧下降,有些地区的甘草资源濒临枯竭。例如,东北松嫩平原,原是我国“东草”商品的主产区之一,并大量出口国外,     

The malmö polymorphism of coagulation factor IX, an immunologic polymorphism due to dimorphism of residue 148 that is in linkage disequilibrium with two other F.IX polymorphisms

A mouse monoclonal antibody (MAB 9.9) to coagulation factor IX (F.IX) detects a polymorphism in the plasma of normal people. Its epitope has been narrowed down to <6 amino acids in the activation peptide of the X-linked F.IX protein. The activation peptide contains a dimorphism—Thr:Ala—at position 148 of the protein. Using synthetic oligonucleotides, we have demonstrated that (1) the F.IX which reacts with 9.9 has Thr at position 148 and (2) that which does not has Ala. Positive reactors (148^thr) are designated Malmö A, and negative reactors (148^ala) are designated Malmö B. The plasma levels of AA women are indistinguishable from those of A men, and both B men and BB women are null against MAB 9.9. The plasma level of Malmö A in AB women is approximately half that of AA women, and “lyonization” is clearly operating in the heterozygotes. The dimorphism is in strong linkage disequilibrium with two other intragenic RFLPs, TaqI and XmnI. Furthermore, intragenic crossing-over—including double crossing-over—appears to have occurred between the three sites. Seven of the eight possible haplotypes have been identified, five in men and two others in women. The immunoassay that identifies ～50% of the AB women in the pool of Malmö A females with 95% confidence identifies men unambiguously as A or B. The assay would be very useful for population-genetic studies of the Malmö epitope if the studies were limited to men.