Effect of boron application on barley in a sierozem sandy soil

Summary In a pot culture experiment on a sierozem sandy soil (pH 8.2) rates of added B at 3 ppm although decreased root yield significantly but shoot and grain yield was unaffected even at 6 ppm added B, even though shoot B concentration was as high as 360 ppm and Ca/B ratio as low as 11. At 6 ppm applied B, shoot yield was increased by 18.5 per cent, whereas grain yield was at par with control. The results suggested that Ca/B ratio in barley straw was not a reliable index for determing the magnitude of B problem in the soil.     

Structure and function in galactosyltransferase. Sequence locations of alpha-lactalbumin binding site, thiol groups, and disulfide bond

The region(s) of bovine galactosyltransferase that interacts with the lactose synthase regulatory protein alpha-lactalbumin was investigated using trace 3H acetylation to probe the effects of alpha-lactalbumin on the reactivities of the individual amino groups of galactosyltransferase. In the presence of Mn2+, alpha-lactalbumin was found to reduce the reactivities of lysines 93 and 181 and to increase the reactivities of one or more of lysines 230, 237, and 241. The addition of N-acetylglucosamine (20 mM), which enhances complex formation between the two proteins, did not significantly alter the pattern of perturbation. These results indicate that the NH2-terminal region of the catalytic domain of galactosyltransferase, and possibly part of the proline-rich "stem" region, is affected by the association with alpha-lactalbumin and is therefore implicated in the binding of acceptor substrates. In a separate study only cysteines 176, 266, and 342 of galactosyltransferase were found to react with [3H]iodoacetic acid under denaturing conditions. From their lack of reactivity it is deduced that the remaining two cysteines, residues 134 and 247, are joined in a disulfide linkage. From these results and those of a previous study of UDP-galactose binding (Yadav, S., and Brew, K. (1990) J. Biol. Chem. 265, 14163-14169) it appears that the soluble form of galactosyltransferase is composed of two domains, the NH2-terminal 150 residues containing the Cys134-Cys247 disulfide bond, which functions in alpha-lactalbumin and acceptor binding, and the COOH-terminal region, which is involved in UDP-galactose binding.     

Synergistic effect of heat-shock and UV-irradiation on mitosis and protein synthesis in G2-phase plasmodia of Physarum polycephalum Schw--reduction in UV-induced mitotic delay in a preheat-shocked system

The synergistic effect of UV irradiation and heat-shock during the last 3 hr of G2 phase of the cell cycle in the plasmodia of P. polycephalum, in terms of mitotic delay and inhibition of protein synthesis, has been evaluated. The mitotic delay due to both perturbers coordinately increased closer to mitosis. Maximum mitotic delay was obtained in plasmodia heat-shocked after UV irradiation, indicating the presence in this system of either a heat-labile mitogenic substance which is comparatively less susceptible to UV or a substance which is made more susceptible to hyperthermia by UV. A protective role for heat-shock applied before irradiation has been observed in that, radiation-induced mitotic delay is significantly reduced in this combination. There was severe inhibition of translation in all the perturbed classes. Organelle level effects which are independent of major protein synthetic activities or different levels of heat-shock protein production could be the reason for the lack of correlation between percentage inhibition of general protein synthesis and the extent of mitotic delay with respect to the two double-perturbed systems.     

Effect of some natural pesticides on entomogenous muscardine fungi.

Five commercial preparations of natural pesticides were tested for in vitro compatibility with muscardine fungi, Beauveria brongniartii and Metarhizium anisopliae. Neemark (azadirachtin) was found compatible with both the fungi. Phytoallexin, the natural fungicide, significantly inhibited the growth of both the fungi, while other natural pesticides showed moderate to severe inhibition.     

Chemical cross-linking study of complex formation between methylamine dehydrogenase and amicyanin from Paracoccus denitrificans

Two soluble periplasmic redox proteins from Paracoccus denitrificans, the quinoprotein methylamine dehydrogenase and the copper protein amicyanin, form a weakly associated complex that is critical to their physiological function in electron transport [Gray, K. A., Davidson, V. L., & Knaff, D. B. (1988) J. Biol. Chem. 263, 13987-13990]. The specific interactions between methylamine dehydrogenase and amicyanin have been studied by using the water-soluble cross-linking agent 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC). Treatment of methylamine dehydrogenase alone with EDC caused no intermolecular cross-linking but did cause intramolecular cross-linking of this alpha 2 beta 2 oligomeric enzyme. The primary product that was formed contained one large and one small subunit. Methylamine dehydrogenase and amicyanin were covalently cross-linked in the presence of EDC to form at least two distinct species, which were identified by nondenaturing polyacrylamide gel electrophoresis (PAGE). The formation of these cross-linked species was dependent on ionic strength, and the ionic strength dependence was much greater at pH 6.5 than at pH 7.5. The effects of pH and ionic strength were different for the different cross-linked products. SDS-PAGE and Western blot analysis of these cross-linked species indicated that the primary site of interaction for amicyanin was the large subunit of methylamine dehydrogenase and that this association could be stabilized by hydrophobic interactions. In light of these results a scheme is proposed for the interaction of amicyanin with methylamine dehydrogenase that is consistent with previous data on the physical, kinetic, and redox properties of this complex.     

Light microscopic features of the rete testis,the vas efferens,the epididymis and the vas deferens in the adult rhesus monkey

The present study was carried out to determine the detailed histological and cytological features of the excurrent ducts of the male reproductive system in the rhesus monkey. The excurrent ducts show a regional difference in their histological features. The use of some of these features as histological markers and their possible functional significance are discussed. The epithelial cells in the different components of the excurrent duct system possess cytological features which suggest their involvement in absorption and the secretion of different products into the lumen.