蝮蛇毒抗凝血活酶组份及几种蛇毒粗毒对人红细胞和血小板的作用

蝮蛇毒抗凝血活酶组分及蝗蛇毒、圆斑蝰蛇毒和眼镜蛇毒粗毒,不仅能够水解血浆中的磷脂,而且还能水解完整人红细胞膜和完整人血小板膜上的磷脂。但是五步蛇毒和金环蛇毒粗毒却不能水解完整人血小板膜上的磷脂。 扫描电镜观察表明,由于抗凝血活酶组份和几种蛇毒粗毒的作用,人红细胞和人血小板的形态发生了巨大的变化;人红细胞由正常的双圆盘形变成带刺的小球,人血小板的外形变成蜂窝状。     

The nucleotide sequence of a rat liver glutathione S-transferase subunit cDNA clone

We have determined the nucleotide sequence of a cloned cDNA derived from liver poly(A) RNA of pentobarbital-treated rats encoding a glutathione S-transferase subunit. This cDNA clone pGTR261 contains one open reading frame of 222 amino acids, a complete 3' noncoding region, and 63 nucleotides in the 5' noncoding region. The cloned DNA hybridizes to rat poly(A) RNA in a tissue-specific fashion, with strong signals to liver and kidney poly(A) RNA(s) of approximately 1100 and approximately 1400 nucleotides in size but little or no hybridization to poly(A) RNAs from heart, lung, seminal vesicles, spleen, or testis under stringent conditions. Our sequence covers the cDNA sequence of pGST94 which contains a partial coding sequence for a liver glutathione S-transferase subunit of Ya size. Comparison of sequences with our earlier clone pGTR112 suggests that there are at least two mRNA species coding for two different subunits of the Ya (Mr = 25,600) subunit family with very limited amino acid substitutions mainly of conserved polarity. The divergent 3' noncoding sequences should be useful molecular probes in differentiating these two different but otherwise very similar subunits in induction and genomic structure analyses. Our results suggest that tissue-specific expression of the glutathione S-transferase subunits represented by the sequences of pGTR261 and pGTR112 may occur at or prior to the level of RNA processing.     

Influences of medium consistency and shoot density on in vitro shoot proliferation of Populus alba × P. grandidentata

The in vitro shoot proliferation of Populus alba × P. grandidentata was affected by the medium consistency and shoot density, but not by three sizes of vessels. After 4 weeks of culture, the fresh weight and number of shoots per explant on liquid medium were significantly greater than those on agar-solidified medium. In particular, 3.2 shoots, 7 mm or longer per explant, were produced on liquid medium compared with 1.6 shoots per explant or agar-solidified medium. The fresh weight per explant after 4 weeks of culture on liquid medium and agar-solidified medium were 0.68 and 0.25 g, respectively. Increasing the number of shoots per vessel slowed the growth of the explants as measured by fresh weight and the number of shoots produced. There was little difference in the number of shoots produced between vessels with 1 or 2 shoots per vessel, but there were many fewer shoots produced when 3 shoots were placed in each vessel.Journal Paper No. J-11977 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 2210.     

Cloning and sequence analysis of a cDNA for a rat liver glutathione S-transferase Yb subunit.

We have isolated a Yb-subunit cDNA clone from a GSH S-transferase (GST) cDNA library made from rat liver polysomal poly(A) RNAs. Sequence analysis of one of these cDNA, pGTR200, revealed an open reading frame of 218 amino acids of Mr = 25,915. The deduced sequence is in agreement with the 19 NH2-terminal residues for GST-A. The sequence of pGTR200 differs from another Yb cDNA, pGTA/C44 by four nucleotides and two amino acids in the coding region, thus revealing sequence microheterogeneity. The cDNA insert in pGTR200 also contains 36 nucleotides in the 5' noncoding region and a complete 3' noncoding region. The Yb subunit cDNA shares very limited homology with those of the Ya or Yc cDNAs, but has relatively higher sequence homology to the placental subunit Yp clone pGP5. The mRNA of pGTR200 is not expressed abundantly in rat hearts and seminal vesicles. Therefore, the GST subunit sequence of pGTR200 probably represents a basic Yb subunit. Genomic DNA hybridization patterns showed a complexity consistent with having a multigene family for Yb subunits. Comparison of the amino acid sequences of the Ya, Yb, Yc, and Yp subunits revealed significant conservation of amino acids (approximately 29%) throughout the coding sequences. These results indicate that the rat GSTs are products of at least four different genes that may constitute a supergene family.     

Modification of Oudin’s method of single immunodiffusion in agar gel for detection of IgA in bronchoalveolar lavage of white mice

Oudin’s principle of single immunodiffusion in agar gel was modified for quantitative determination of IgA in bronchoalveolar lavage (BAL) of normal 20–25 g mice. The reaction took place at 25 °C in 0.3 % agarose with 16.7 % pig serum against mouse IgA, and was evaluated on the basis of a relationship between the progress of the precipitin zone and the square root of time. The linear dependence of the derived constantk on the logarithmic concentration of antibody in the sample permitted to express the results as titre, corresponding to a dilution wherek = 0. Examination of seven samples of pooled blood serum of normal mice shoved taht (1) the IgA level was practically constant, (2) serum IgA possessed under given conditions similar properties as IgA from the bronchoalveolar secretion; it is therefore possible to employ pooled sera as a reliable control of the immunodiffusion system in ease of lack of reference standards with defined IgA content. Examination of 82 individual BAL samples of normal mice revealed that the mean IgA concentration in 2.5 mL samples was almost 1000 times lower than in blood serum.     

Tissue-specific expression of the rat glutathione S-transferases

Tissue-specific patterns of rat glutathione S-transferase expression have been demonstrated by in vitro translation of purified poly(A) RNAs and by protein purification. Poly(A) RNAs from six rat tissues including heart, kidney, liver, lung, spleen, and testis were used to program in vitro translation with the rabbit reticulocyte lysate system and [35S]methionine. The glutathione S-transferase subunits synthesized in vitro were purified from the translation products by affinity chromatography on S-hexylglutathione-linked Sepharose 6B columns. The affinity bound fractions were analyzed by Na dodecyl SO4-polyacrylamide gel electrophoresis and fluorography. A subunit of Mr = 22,000 detected in the in vitro translation products of poly(A) RNAs from heart, kidney, lung, spleen, and testis is missing from the translation products of liver poly(A) RNAs. This Mr = 22,000 subunit is present only in the anionic glutathione S-transferase fraction purified from rat heart, kidney, lung, spleen, and testis. Purified anionic glutathione S-transferase from rat liver does not contain this subunit. The relative specific activities toward a dozen different substrates also demonstrate the nonidentity between liver and kidney anionic glutathione S-transferases. In addition, among the glutathione S-transferase subunits expressed in the liver, some of them could not be detected in the other tissues investigated. Our results indicate that tissue-specific expression of rat glutathione S-transferases may occur pretranslationally.     

Characterization of lizard venom hyaluronidase and evidence for its action as a spreading factor

Hyaluronidase was isolated from the lizard (Heloderma horridum horridum) crude venom. The chemical properties were characterized and compared to the same enzyme from other sources. The enzyme was found to be a single polypeptide chain with a molecular weight of 63,000 daltons. It possesses an isoelectric point and pH optimum of 5.0, and was observed to be extremely temperature sensitive. The role of hyaluronidase as a spreading factor which serves to aid in the diffusion of toxins has been suspected for a long time; yet no experimental proof has been offered until now. It was shown that hyaluronidase promotes the spread of the hemorrhagic area in mice when injected with hemorrhagic toxin. Thus experimental evidence is supplied for the first time that the enzyme plays a role as a "spreading factor" in the toxic action of venom.     

Relationship Between the Membrane Envelope of Rhizobial Bacteroids and the Plasma Membrane of the Host Cell as Demonstrated by Histochemical Localization of Adenyl Cyclase

By using adenyl cyclase as a marker enzyme, the relationship between the membrane envelope of the bacteroids of rhizobia and the plasma membrane of the host cell was demonstrated histochemically. Electron-dense deposits were found on the outer surface of the plasma membrane of the host cell and on the inner surface of the membrane envelopes of the bacteroids, but not in vacuole membranes, endoplasmic reticula, Golgi apparatus, and mitochondrial membranes. The results suggest that the membrane envelopes of the bacteroids are closely related to the host plasma membrane, and that entry of the bacteroids into the cytoplasm is in a manner similar to endocytosis.