ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα

ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα.     

NMR study of in vivo RIF-1 tumors: Analysis of perchloric acid extracts and identification of 1H, 31P and 13C resonances

Perchloric acid extracts of radiation-induced fibrosarcoma (RIF-1) tumors grown in mice have been analyzed by multinuclear NMR spectroscopy and by various chromatographic methods. This analysis has permitted the unambiguous assignment of the ³¹P resonances observed in vivo to specific phosphorus-containing metabolites. The region of the in vivo spectra generally assigned to sugar phosphates has been found in RIF-1 tumors to contain primarily phosphorylethanolamine and phosphorylcholine rather than glycolytic intermediates. Phosphocreatine was observed in extracts of these tumor cells grown in culture as well as in the in vivo spectra, indicating that at least some of the phosphocreatine observed in vivo arises from the tumor itself and not from normal tissues. In the ³¹P-NMR spectra of the perchloric acid extract, resonances originating from purine and pyrimidine nucleoside di- and triphosphate were resolved. HPLC analyses of the nucleotide pool indicate that adenine derivatives were the most abundant components, but other nucleotides were present in significant amounts. The ¹H and ¹³C resonance assignments of the majority of metabolites present in RIF-1 extracts have also been made. Of particular importance is the ability to observe lactate, the levels of which may provide a noninvasive measure of glycolysis in these cells in both the in vivo and in vitro states. In addition, the aminosulfonic acid, taurine, was found in high levels in the tumor extracts.     

Analysis of nutrient components of food for Asian elephants in the wild and in captivity

Thirty-seven wild plants as food for Asian elephants in the field in Simao, Yunnan province, China and five cultivated plants as food for captive elephants in the Beijing Zoo were collected and analyzed for their main nutrient components. Protein, fat, fiber, dry material, ash as well as major microelements: calcium, kalium, zincum, sodium in the food were analyzed by standard methodology. No significant differences were found between the wild plants taken in the field and forage provided in captivity. However, the calcium content in the forage is significantly less than the average of those in the wild plants. It is suggested that the increase in calcium intake may contribute to the relief of low plasma calcium diseases of elephants in captivity. Translated from Journal of Beijing Normal University (Natural Science), 2006, 42(2): 184–188 [译自: 北京师范大学学报 (自然科学版)]     

Preliminary study of the physical chemistry and catalytic properties of glutathione-S-transferase from human placenta

Glutathione-S-transferase activity has been identified in the cytosol of human placenta. The specific activity measured is about 50% of that found in human liver. While some kinetic data have a close correspondence with those attributed to transferases of other sources, the molecular weight (60.000 daltons) and electric properties of this protein are unusual. The inhibitory effect of several non-substrate compounds suggests that also the placental Glutathione-S-transferase may play some role in detoxication of exogenous substances.     

Isolation and properties of a thialysine-resistant clone of CHO cells

A variant clone of Chinese hamster ovary (CHO) cells resistant to thialysine has been isolated. It maintains the phenotypic properties even after 250 generations in medium without thialysine. Growth rate, cell viability and protein synthesis rate of the variant are much less affected by thialysine than the parental strain. In both the parental strain and the variant, thialysine acts in competition with lysine as indicated by the fact that all thialysine effects can be completely reversed by lysine.