Requirement of calmodulin binding by HIV-1 gp160 for enhanced FAS-mediated apoptosis

Accelerated apoptosis is one mechanism proposed for the loss of CD4+ T-lymphocytes in human immunodeficiency virus type 1 (HIV-1) infection. The HIV-1 envelope glycoprotein, gp160, contains two C-terminal calmodulin-binding domains. Expression of gp160 in Jurkat T-cells results in increased sensitivity to FAS- and ceramide-mediated apoptosis. The pro-apoptotic effect of gp160 expression is blocked by two calmodulin antagonists, tamoxifen and trifluoperazine. This enhanced apoptosis in response to FAS antibody or C(2)-ceramide is associated with activation of caspase 3, a critical mediator of apoptosis. A point mutation in the C-terminal calmodulin-binding domain of gp160 (alanine 835 to tryptophan, A835W) eliminates gp160-dependent enhanced FAS-mediated apoptosis in transiently transfected cells, as well as in vitro calmodulin binding to a peptide corresponding to the C-terminal calmodulin-binding domain of gp160. Stable Tet-off Jurkat cell lines were developed that inducibly express wild type gp160 or gp160A835W. Increasing expression of wild type gp160, but not gp160A835W, correlates with increased calmodulin levels, increased apoptosis, and caspase 3 activation in response to anti-FAS treatment. The data indicate that gp160-enhanced apoptosis is dependent upon calmodulin up-regulation, involves the activation of caspase 3, and requires calmodulin binding to the C-terminal binding domain of gp160.     

中药柴胡不同采收期的皂甙含量

中药柴胡不同采收期的皂甙含量潘泽惠庄体德周雪林林湘（江苏省中国科学院植物研究所,南京２１００１４）（黑龙江双鸭山矿务局师范学校,双鸭山１５５１２５）ＯｎｓｅａｓｏｎａｌｃｈａｎｇｅｓｏｆｔｈｅｔｏｔａｌｓａｐｏｎｉｎｓｉｎＣｈｉｎｅｓｅｔｒａｄｉｔ...     

Endogenous hydrogen sulfide regulation of myocardial injury induced by isoproterenol

Previous work has shown that the endogenous cystathionine γ-synthase (CSE)/hydrogen sulfide (H₂S) pathway participates in the regulation of cardiac contraction. We hypothesized that the pathway might participate in the pathophysiological regulation of ischemic heart disease. Isoproterenol injection of rat hearts induced a myocardial ischemic injury model, with reduced myocardial and plasma H₂S levels, decreased CSE activity, and upregulated CSE gene expression. Exogenous administration of the H₂S donor NaHS reduced the mortality rate; increased left-ventricular pressure development and left-ventricular-end systolic pressure; and decreased left-ventricular-end diastolic pressure (LVEDP) and subendocardial necrosis, capillary dilatation, leukocytic infiltration, fibroblast swelling, and fibroblastic hyperplasia. As well, production of lipid peroxidation, including myocardial malondialdehyde (MDA), and plasma MDA and conjugated diene, was reduced. Oxidative stress injury is an important mechanism of isoproterenol-induced myocardial injury. In vitro experiments revealed that NaHS might antagonize myocyte MDA production by oxygen-free radicals and that NaHS directly scavenged hydrogen peroxide and superoxide anions. Our results suggest that the endogenous CSE/H₂S pathway contributes to the pathogenesis of isoproterenol-induced myocardial injury. Administration of exogenous H₂S effectively protects myocytes and contractile activity, at least by its direct scavenging of oxygen-free radicals and reducing the accumulation of lipid peroxidations.     

Phytochemistry and biosynthesis of δ-lactone withanolides

Withanolides are highly oxygenated natural products. These C₂₈ steroids with ergostane-based skeletons functionalized at C-22 and C-26 form six-membered δ-lactone rings. Withanolides containing a δ-lactone side chain often occur in Solanaceae and have a variety of biological activities because of their complicated structures. Characteristic spectroscopic behaviors and biosynthesis of withanolides are conducive to their structural elucidation and “biomimetic synthesis”, respectively. However, the last review to summarize their spectroscopic features and biosynthesis was in 1996. Since then, many withanolides with novel structures have been described by their spectra with biosynthesis investigated with many bioassays. This review surveys δ-lactone withanolides and emphasizes their spectral features, configurations and biosynthetic genes. The period reviewed includes through January 2014. We also include phytochemical species.     

Antisense expression of Gossypium barbadense UGD6 in Arabidopsis thaliana significantly alters cell wall composition

Uridine diphosphate-glucose dehydrogenase (UGD, EC1.1.1.22 oxidizes UDP-Glc (UDP-D-glucose) to UDP-GlcA (UDP-Dglucuronate), a critical precursor of cell wall polysaccharides. GbUGD6 from Gossypium barbadense is more highly expressed late in the elongation of cotton fibers (15 d post-anthesis (DPA)) and during the stage of secondary cell wall thickening (30 DPA). Subcellular localization analysis in onion epidermis revealed that fluorescently labeled GbUGD6 protein was distributed throughout the cell membrane, as well as the nucleus and vacuoles. Examination of UGD function in Arabidopsis revealed that the antisense GbUGD6 lines had shorter roots, deferred blossoming, compared to wild-type plants. Activities of associated enzymes were also affected by UGD reduction, and biochemical analysis of cell wall samples showed an increase in cellulose levels and a decrease in UGP-GlcA contents. The results of the present study as well as previous studies on UGD support the conclusion that UGD plays a major role in synthesizing polysaccharides synthesis in the cell wall.     

The activity parameters,cDNA cloning and mRNA expression of lysozyme in Cyclina sinensis (Bivalvia,Veneridae) responding to the pathogenic bacterium Vibrio anguillarum

ABSTRACT

Lysozyme is an important component of the innate immune response against pathogen infection. The functional forms have been well-studied in the c-type lysozymes of vertebrates but less so in i-type lysozymes prevalent in most invertebrate animals. Cyclina sinensis is a commercially important marine venerid bivalve that is abundant and widely distributed around the maritime coasts of Asia. We obtained an i-type lysozyme (i-lyz) gene in C. sinensis by large scale EST sequencing of a SMART-cDNA library. In C. sinensis, the i-lyz gene encodes 181 amino acids. The lysozyme activities and the mRNA levels of the i-lyz gene in haemocytes were upregulated during the infection by a bacterium, Vibrio anguillarum. The lysozyme activity in haemocytes was increased after 12?h infection by V. anguillarum, and reached the highest level at 24?h post-infection, which was significantly higher than that of the control group (P?<?0.01). The expression level of the i-lyz gene in haemocytes was increased after 3?h infection of Vibrio, and reached the highest level at 6?h post-infection. A recombinant i-lyz was obtained through prokaryotic expression which, when isolated and purified, had a molecular weight of approximately 19?kDa. Western blotting was used to validate the expression of the fusion protein. Furthermore, we demonstrate that the recombinant i-lyz protein has obvious bacteriostatic activity upon Escherichia coli whereby the K value of the curve was significantly lower than control and blank groups. Our study shows that the C. sinensis i-type lysozyme plays an important role in the immune defence against V . anguillarum and provides a theoretical reference for clarifying the mechanism of immune response against pathogen invasion in this bivalve.     

Physiological basis of the synergistic effects of IBA and triadimefon on rooting of mung bean hypocotyls

Mixtures of 1–3 × 20.32 mg L^-1 IBA and 1–3 × 289.5 µg L^-1 triadimefon (TRI) significantly increased the formation of adventitious roots in mung bean hypocotyl cuttings compared to application of either IBA or TRI alone. The physiological basis of the synergistic effects of the mixture is likely to be due to a combination of increased endogenous IAA content and peroxidase activity. It is suggested that a mixture of IBA with TRI at appropriate concentrations is an effective and simple method for promoting adventitious root formation.     

Distribution of the flavohaemoglobin, HMP, between periplasm and cytoplasm in Escherichia coli

Abstract The subcellular distribution of the soluble flavohaemoglobin (HMP) of Escherichia coli has been determined. Cells over-expressing HMP from the cloned hmp gene on a multicopy plasmid were fractionated by osmotic shock and lysozyme treatment. Spectral analysis of subcellular fractions showed the CO-binding haemoprotein to be cytoplasmic. However, Western blotting using antibody raised to purified HMP revealed approximately 30% of the protein to be periplasmic in the over-expressing strain. Western analysis also revealed substantial levels of periplasmic HMP in a strain expressing only chromosomally encoded protein but none in an hmp mutant. The results are discussed in relation to protein function and the similar distribution reported for Vitreoscilla globin.