Nature of inhibition of rat testicular alkaline phosphatase by isatin

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 Km and Vmax in the presence of isatin.     

Synaptosomal adenosine triphosphatase (ATPase) inhibition by organophosphates.

Chicken spinal cord adenosine triphosphatases (both Na+, K+ stimulated and ouabain insensitive) were inhibited by tri-o-tolyl phosphate (TOTP, a neurotoxic organophosphate which is not a cholinesterase inhibitor) and mevinphos (a non-neurotoxic compound but inhibitor of cholinesterases). The inhibition was concentration and time dependent, with an initial rapid drop in activity followed by a gradual exponential decline.     

A new observation onHalobacterium halobium; light-induced volume flow through the whole organism

Summary A new observation on theH. halobium cells is reported. It has been observed that when the cells are exposed to light a volume flow is observed through them. The magnitude of the light-induced volume flow depends on the intensity and wavelength of the exciting light and is also influenced by temperature. The phenomenon appears to be relevant to the physiology of the organism.Acknowledgment. Thanks are due to the Council of Scientific and Industrial Research, New Dehli for financial support and to Dr Th. Schreckenbach of Max Planck Institute of Biochemistry, Germany for his gift of a sample ofHalobacterium halobium S9 strain.     

Electric polarization reversal and memory in a multiferroic material induced by magnetic fields

Ferroelectric and magnetic materials are a time-honoured subject of study and have led to some of the most important technological advances to date. Magnetism and ferroelectricity are involved with local spins and off-centre structural distortions, respectively. These two seemingly unrelated phenomena can coexist in certain unusual materials, termed multiferroics. Despite the possible coexistence of ferroelectricity and magnetism, a pronounced interplay between these properties has rarely been observed. This has prevented the realization of multiferroic devices offering such functionality. Here, we report a striking interplay between ferroelectricity and magnetism in the multiferroic TbMn2O5, demonstrated by a highly reproducible electric polarization reversal and permanent polarization imprint that are both actuated by an applied magnetic field. Our results point to new device applications such as magnetically recorded ferroelectric memory.     

Three dimensional Couette flow and heat transfer through a porous medium with variable permeability

This paper reports research on the effects of variations in injection velocity and permeability on the heat transfer and flow through a highly porous medium between two horizontal parallel plates situated at constant distance with constant suction by the upper plate.Due to this type of variation in injection velocity and in permeability the flow becomes three dimensional.The governing equstions are solved by adopting complex variable notations to obtain the expressions for the velocity and temperature field.The skin-friction along the main flow direction and rate of heat transfer are discussed with the help of graphs.     

The exotoxin ofBacillus thuringiensis: A new C-mitotic agent

Summary Thuringiensin A, an exotoxin fromBacillus thuringiensis, a constituent of the microbial insecticide thuricide has been found to inhibit mitotic spindle, condense and scatter chromosomes. It may therefore be a promizing tool in future cell biological studies.We thank Prof.H. Sharatchandra for facilities. CBSR is a National Associate of the University Grants Commission, New Delhi.