GTP-activated communication between distinct inositol 1,4,5-trisphosphate-sensitive and -insensitive calcium pools

Inositol 1,4,5-trisphosphate (InsP3) is an established mediator of intracellular Ca2+ signals but little is known of the nature and organization of Ca2+ regulatory organelles responsive to InsP3. Here we derive new information from the study of Ca2+ movements induced both by InsP3 and a specific GTP-activated Ca2+ translocation process. The latter mechanism is clearly distinct from that activated by InsP3 and may involve the translocation of Ca2+ between compartments without its release into the cytosol. This idea is supported by the fact that GTP activates Ca2+ movement into the InsP3-releasable pool. In the light of this evidence we postulated that there are two intracellular Ca2+ pools distinguishable by InsP3-sensitivity and oxalate-permeability, and that movement between them is activated by GTP. We report here direct evidence for the existence and separation of two distinct Ca2+-pumping compartments with properties coinciding with those predicted. Of these, the InsP3-sensitive Ca2+ pool is identified within a purified rough endoplasmic reticulum fraction, an observation consistent with recent InsP3 receptor-localization studies. Ca2+ translocation between pools may reflect function of a class of small GTP-binding proteins known to mediate interorganelle transfer in eukaryotic cells.     

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.     

Kinetic studies on the reduction of iron ore nuggets by devolatilization of lean-grade coal

An isothermal kinetic study of a novel technique for reducing agglomerated iron ore by volatiles released by pyrolysis of lean-grade non-coking coal was carried out at temperature from 1050 to 1200°C for 10–120 min. The reduced samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chemical analysis. A good degree of metallization and reduction was achieved. Gas diffusion through the solid was identified as the reaction-rate-controlling resistance; however, during the initial period, particularly at lower temperatures, resistance to interfacial chemical reaction was also significant, though not dominant. The apparent rate constant was observed to increase marginally with decreasing size of the particles constituting the nuggets. The apparent activation energy of reduction was estimated to be in the range from 49.640 to 51.220 kJ/mol and was not observed to be affected by the particle size. The sulfur and carbon contents in the reduced samples were also determined.     

Estimates of the population by ethnic group for areas within England

This article describes, and provides some initial analysis of, the experimental population estimates by ethnic group for areas within England published by the Office for National Statistics (ONS) in January 2006. The article considers growth and the population structure of each of the ethnic groups identified in the 2001 Census; subnational patterns of change; population turnover; and measures of diversity and segregation, and also provides a comparison of the estimates and corresponding sample-based estimates from the Labour Force Survey.     

Forecasting with preliminary data

This paper examines several methods to forecast revised US trade balance figures by incorporating preliminary data. Two benchmark forecasts are considered: one ignoring the preliminary data and the other applying a combination approach; with the second outperforming the first. Competing models include a bivariate AR error-correction model and a bivariate AR error-correction model with GARCH effects. The forecasts from the latter model outperforms the combination benchmark for the one-step forecast case only. A restricted AR error-correction model with GARCH effects is discovered to provide the best forecasts. © 1997 John Wiley & Sons, Ltd.     

A convenient thin layer chromatographic method for the detection of cyclochlorotine and simatoxin, toxins from Penicillium islandicum Sopp

A rapid, convenient TLC method is described for detection of cyclochlorotine, a carcinogen produced by the commonly found storage mold Penicillium islandicum Sopp. This method has also led to the isolation of a new toxic metabolite, simatoxin.     

Formaldehyde-Schiff's reagent as a nucleolar strain.

The use of formaldehyde-Schiff's reagent as a nucleolar stain has been described. Using different digestion procedures, it was confirmed that the stain is specific for RNA. It can be suitably used as a nucleolar stain, particularly in plant materials after a short TCA extraction, which probably extracts the nonbound RNA.