Nature of inhibition of rat testicular alkaline phosphatase by isatin

Summary Isatin has been found to inhibit rat testicular alkaline phosphatase (EC 3.1.3.1). That the inhibition is non-competitive as well as non-allosteric is evident from a) the hyperbolic curve relating inhibition as a function of inhibitor concentration; b) the small change in enthalpy, free energy and entropy; c) the number of isatin molecules associating with 1 molecule of the enzyme (n=1.29); and, d) the decrease in the values of both K_m and V_max in the presence of isatin.     

Ca2+-dependence and metabolic status of an obligate thermophile,Thermoactinomyces vulgaris,under shake culture conditions

Summary Ca²⁺ stimulates germination ofT. vulgaris spores. There is a higher mycelial yield as well as higher protein, DNA, RNA and free Pi content in cultures grown in the presence of Ca²⁺ as compared to those grown in the absence of this divalent cation.Grateful thanks are due to Professor R. P. Roy for providing the necessary facilities. V. P. S. acknowledges with thanks the receipt of a Post Doctoral Research Fellowship of the Council of Scientific and Industrial Research, New Delhi.     

Tbx2 and Tbx3 induce atrioventricular myocardial development and endocardial cushion formation

A key step in heart development is the coordinated development of the atrioventricular canal (AVC), the constriction between the atria and ventricles that electrically and physically separates the chambers, and the development of the atrioventricular valves that ensure unidirectional blood flow. Using knock-out and inducible overexpression mouse models, we provide evidence that the developmentally important T-box factors Tbx2 and Tbx3, in a functionally redundant manner, maintain the AVC myocardium phenotype during the process of chamber differentiation. Expression profiling and ChIP-sequencing analysis of Tbx3 revealed that it directly interacts with and represses chamber myocardial genes, and induces the atrioventricular pacemaker-like phenotype by activating relevant genes. Moreover, mutant mice lacking 3 or 4 functional alleles of Tbx2 and Tbx3 failed to form atrioventricular cushions, precursors of the valves and septa. Tbx2 and Tbx3 trigger development of the cushions through a regulatory feed-forward loop with Bmp2, thus providing a mechanism for the co-localization and coordination of these important processes in heart development.     

Comparison of the production rates of bacteria in the rumen estimated by using labelled live and formaldehyde treated mixed bacterial cells

Summary The bacteria production rates in the rumen have been estimated by injecting¹⁴C- and³⁵S-labelled mixed rumen bacteria, either live or killed by treatment with formaldehyde, into the rumen and applying isotope dilution technique. The rate of bacteria production when estimated by using either live- or dead-(protected-)labelled bacterial cells were comparable.     

Isolation and structure of the strong cell growth and tubulin inhibitor combretastatin A-4

The African tree Combretum caffrum (Combretacae) has been found to contain a powerful inhibitor of tubulin polymerization (IC50 2-3 microM), the growth of murine lymphocytic leukemia (L 1210 and P 388 with ED50 approximately 0.003 microM and human colon cancer cell lines [(e.g. LoVo (ED50 = 0.005 microgram/ml), HT 29 (ED50 0.02 microgram/ml, Colo 205 (ED50 = 0.07 microgram/ml), DLD-1 (ED50 = 0.005 microgram/ml) and HCT-15 (ED50 = 0.0009 microgram/ml] designated combretastatin A-4 (1c). The structure assigned by spectral techniques was confirmed by synthesis.