Effect of ascorbic acid on pigmentation of toad (Bufo melanostictus).

Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.     

A structural basis for allosteric control of DNA recombination by lambda integrase

Site-specific DNA recombination is important for basic cellular functions including viral integration, control of gene expression, production of genetic diversity and segregation of newly replicated chromosomes, and is used by bacteriophage lambda to integrate or excise its genome into and out of the host chromosome. lambda recombination is carried out by the bacteriophage-encoded integrase protein (lambda-int) together with accessory DNA sites and associated bending proteins that allow regulation in response to cell physiology. Here we report the crystal structures of lambda-int in higher-order complexes with substrates and regulatory DNAs representing different intermediates along the reaction pathway. The structures show how the simultaneous binding of two separate domains of lambda-int to DNA facilitates synapsis and can specify the order of DNA strand cleavage and exchange. An intertwined layer of amino-terminal domains bound to accessory (arm) DNAs shapes the recombination complex in a way that suggests how arm binding shifts the reaction equilibrium in favour of recombinant products.     

Effect of ascorbic acid on pigmentation of toad (Bufo melanostictus)

Summary Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.Acknowledgment. The authors' thanks are due to Prof.C. Deb, Head of the Department of Physiology, Calcutta University, for encouragements.     

浑善达克榆树疏林自然保护区缓冲区宽度研究

 世界上建设有很多森林自然保护区以保护各种类型的森林,自然保护区的核心区外围常常要求建设缓冲区,但是如何设计缓冲区宽度的研究很少。土壤种子库是衡量退化森林生态系统生态恢复潜力的重要指标,利用种子库进行缓冲区的设计。采用植物群落学调查及种子库分析的方法,在核心区内外选择一系列样方,调查样方种子库及其地面的植物种类组成,计算样方与核心区种子库、植物群落的相似性指数,根据核心区外不同距离的样方的相似性指数,确定了缓冲区的宽度。研究结果发现,缓冲区最低宽度在低地为300 m,在流动沙地为600 m,在固定沙地和半固定沙地为1 000~1 200 m。对于沙漠化地区的自然保护区缓冲区的设计有一定的借鉴价值。     

Microbial leaching of chromite overburden from Sukinda mines, Orissa, India using Aspergillus niger

Leaching of nickel and cobalt from two physical grades (S1, 125–190 μm, coarser and S3, 53–75 μm, finer) of chromite overburden was achieved by treating the overburden (2% pulp density) with 21-d culture filtrate of an Aspergillus niger strain grown in sucrose medium. Metal dissolution increases with ore roasting at 600°C and decreasing particle size due to the alteration of microstructural properties involving the conversion of goethite to hematite and the increase in surface area and porosity as evident from X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (DT-TGA), and field emission scanning electron microscopy (FESEM). About 65% Ni and 59% Co were recovered from the roasted S3 ore employing bioleaching against 26.87% Ni and 31.3% Co using an equivalent amount of synthetic oxalic acid under identical conditions. The results suggest that other fungal metabolites in the culture filtrate played a positive role in the bioleaching process, making it an efficient green approach in Ni and Co recovery from lateritic chromite overburden.     

Ascorbic acid and testicular activity in heat-exposed toad (Bufo melanostictus)

Résumé On a trouvé que la fonction du testicule et la concentration de l'acide ascorbique dans cette glande ont été augmentées chez les crapauds exposés à la chaleur.     

Testicular Δ5-3β dehydrogenase,ascorbic acid and dehydroascorbic acid in actinomycin D-treated toads

Summary Unilaterally intratesticular injection of actionomycin D in toad inhibited ⁵-3 dehydrogenase activity with significant increase of dehydroascorbic acid and decrease of ascorbic acid level in the testis.Acknowledgments. Thanks are due to Prof. C. Deb, Department of Physiology, Calcutta University, for his suggestions and constant encouragment. Thanks are also extended to Mr R.K. Bhattacharya Microphotographer Department of Physiology, for his kind cooperation.     

Testicular Leydig cells and 277-1277-1277-1dehydrogenase in cadmium-treated toads (Bufo melanostictus)

Summary Injection of cadmium chloride in toad increased Leydig cell size (area) and ₅-3-hydroxysteroid dehydrogenase activity in the testis.Acknowledgments. We would like to express our thanks to Dr C. Deb, Head of the Department of Physiology, Calcutta University, for his constant encouragement and Mr R. K. Bhattacharya, Microphotographer, Department of Physiology, for his kind cooperation. This work was supported by U. G. C. Teachers' Grants, New Delhi.