Diurnal depth-wise and seasonal changes of physico-chemical factors in Sathiar reservoir

The various physico-chemical factors such as rainfall, depth, water spread, temperature, dissolved oxygen, pH, redox potential, alkalinity, total phosphorus, nitrate, kjeldahl nitrogen and dissolved organic matter were studied both diurnally and seasonally and depth-wise for the period from April 1977 to March 1978. Consideration of physico-chemical factors indicates that they are inter-related. The main characteristics of Sathiar clearly indicate that it is highly eutrophic.     

Response surface methodology for the optimization of <Emphasis Type="Italic">α</Emphasis>-amylase production by <Emphasis Type="Italic">Streptomyces</Emphasis> sp. ML12 using agricultural byproducts

Amylases constitute one of the most important groups of enzymes for commercial use. In the present study, production of α-amylase was optimized using a newly isolated actinobacterial strain from the coral reef environment of the Gulf of Mannar Biosphere Reserve, India. It was identified as Streptomyces sp. ML12 based on chemotaxonomy, cultural and morphological characteristics, carbon source utilization and 16S rRNA gene sequencing. Fermentation variables were selected in accordance with the Plackett-Burman design and were optimized by response surface methodology. Five significant variables (rice bran and wheat bran — both agricultural byproducts, sodium chloride, magnesium sulphate and incubation period) were selected for the optimization via central composite design. The optimal features were rice bran (5.5 g/100 mL), wheat bran (5.3 g/100 mL), sodium chloride (2.8 g/100 mL), magnesium sulphate (1.4 g/100 mL) and 8 days of incubation period. Optimization of the medium with the above tested features increased the amylase yield by 4.4-fold.     

Structure of presynaptic toxins: Crystallization and preliminary x-ray diffraction data on Notechis II-5, a presynaptic toxin phospholipase

The presynaptic neutrotoxin-phospholipase, Notechis II-5 from the venom of NotechisScutatus scutatus (Australian tiger snake) has been crystallized in a form suited for x-ray diffraction analysis. The crystals belong to the orthorhombic space group P2₁ 2₁,2₁, with unit cell dimensions, a=146.1,b =43.5 and c =39.0 A. There are two molecules of Notechis II-5 in the asymmetric unit. The molecular weight is about 13,500. Notechis II-5 is highly homologous to Notexin, another presynaptic toxin from the venom of the Australian tiger snake, to bovine and porcine pancreatic phospholipases A and other venom phospholipases.     

Functional mapping of community‐acquired respiratory distress syndrome (CARDS) toxin of Mycoplasma pneumoniae defines regions with ADP‐ribosyltransferase,vacuolating and receptor‐binding activities

Community‐acquired respiratory distress syndrome (CARDS) toxin from Mycoplasma pneumoniae is a 591‐amino‐acid virulence factor with ADP‐ribosyltransferase (ADPRT) and vacuolating activities. It is expressed at low levels during in vitro growth and at high levels during colonization of the lung. Exposure of experimental animals to purified recombinant CARDS toxin alone is sufficient to recapitulate the cytopathology and inflammatory responses associated with M. pneumoniae infection in humans and animals. Here, by molecular modelling, serial truncations and site‐directed mutagenesis, we show that the N‐terminal region is essential for ADP‐ribosylating activity. Also, by systematic truncation and limited proteolysis experiments we identified a portion of the C‐terminal region that mediates toxin binding to mammalian cell surfaces and subsequent internalization. In addition, the C‐terminal region alone induces vacuolization in a manner similar to full‐length toxin. Together, these data suggest that CARDS toxin has a unique architecture with functionally separable N‐terminal and C‐terminal domains.     

GSH Transport in Immortalized Mouse Brain Endothelial Cells

We have previously shown GSH transport across the blood-brain barrier in vivo and expression of transport in Xenopus laevis oocytes injected with bovine brain capillary mRNA. In the present study, we have used MBEC-4, an immortalized mouse brain endothelial cell line, to establish the presence of Na+-dependent and Na+-independent GSH transport and have localized the Na+-dependent transporter using domain-enriched plasma membrane vesicles. In cells depleted of GSH with buthionine sulfoximine, a significant increase of intracellular GSH could be demonstrated only in the presence of Na+. Partial but significant Na+ dependency of [35S]GSH uptake was observed for two GSH concentrations in MBEC-4 cells in which gamma-glutamyltranspeptidase and gamma-glutamylcysteine synthetase were inhibited to ensure absence of breakdown and resynthesis of GSH. Uniqueness of Na+-dependent uptake in MBEC-4 cells was confirmed with parallel uptake studies with Cos-7 cells that did not show this activity. Molecular form of uptake was verified as predominantly GSH, and very little conversion of [35S]cysteine to GSH occurred under the same incubation conditions. Poly(A)+ RNA from MBEC expressed GSH uptake with significant (approximately 40-70%) Na+ dependency, whereas uptake expressed by poly(A)+ RNA from HepG2 and Cos-1 cells was Na+ independent. Plasma membrane vesicles from MBEC were separated into three fractions (30, 34, and 38% sucrose, by wt) by density gradient centrifugation. Na+-dependent glucose transport, reported to be localized to the abluminal membrane, was found to be associated with the 38% fraction (abluminal). Na+-dependent GSH transport was present in the 30% fraction, which was identified as the apical (luminal) membrane by localization of P-glycoprotein 170 by western blot analysis. Localization of Na+-dependent GSH transport to the luminal membrane and its ability to drive up intracellular GSH may find application in the delivery of supplemented GSH to the brain in vivo.     

Plant Regeneration from Leaf Explants of Three Grain Legumes on Same Medium

The regeneration potential of leaves of moth bean, pigeonpea and grass pea was studied on Murashige and Skoog’s (MS) medium supplemented with various combinations of auxins and cytokinins. Regeneration of shoots was obtained mainly on MS medium supplemented with high auxin and low cytokinin levels. However, frequency of response varied not only in the three legume species but also in their varieties studied. Roots were induced on regenerated shoots by transferring them to MS basal medium. Complete plant regeneration was observed in the three legumes in a short duration of 60–70 days.     

A Markov chain analysis of predator strategy in a model-mimic system

A predator which is preying on a model-mimic system can choose either the single-trial strategy or a multi-trial strategy as its behavior in learning to prudently harvest such a prey system. In this learning behavior, an important and often-posed problem is to determine which among these two strategies is better suited for the predator and why one is preferable over the other. We present in this article, using Markov chain methods, an extensive analysis of these strategies (and also of eat-everything, strategy). We conclude that the multi-trial strategy is the one that the predator should adopt (but we will also describe the situations when the single-trial strategy seems to be better). Our conclusions are based on the comparisons of quantities such as the mean benefit to the predator, energy derived by a predator from the model-mimic system and (a newly introduced notion of) contagion in eating mimics and models (these quantities are computed for different strategies). The first two quantities are functions of the abundancep and noxiousnessb of models. The contagion is a function of onlyp; and, though independent ofb, it is also in support of multi-trial, strategy. We introduce, in the present context, a biological analog of the d'Alembert principle and also derive functions describing the influences of eating a specified type of prey at a given time on eating any type of prey at a later time. Various results of Estabrook-Jespersen (single-trial strategy) and Bobisud-Potratz (multi-trial strategy) are re-derived as special cases of our more general results. A central limit theorem under the eat-everything strategy is given.     

One-pot synthesis of highly functionalized morphans from C-glycosides

Highly functionalized morphan derivatives were synthesized from nitroalkene 2′-(oxoalkyl)-C-glycosides by a tandem reaction that created three (two C–N and one C–C) new bonds and four stereogenic centers in a one-pot procedure under very mild conditions without the use of expensive reagents. The transformation was achieved from a β-elimination/Michael addition cascade, followed by Michael addition of the amine and intramolecular enamination. In the presence of sodium cyanoborohydride the iminium intermediate was reduced in situ to afford the desired morphans.     

Glucagon secretion in chronic pancreatitis.

Plasma insulin, pancreatic glucagon and immunoreactive glucagon-like polypeptide of intestinal origin (enteroglucagon) have been measured in 10 patients with chronic pancreatitis and 5 normal subjects. Basal levels and changes following oral glucose (50 g) and an intravenous infusion of arginine (25 g in 30 min) have been studied. In patients with chronic pancreatitis the plasma insulin response to oral glucose and intravenous arginine was reduced. Basal pancreatic glucagon was increased in the patients and increased further with oral glucose. During an arginine infusion the pancreatic glucagon showed a brisk early increase greater than that seen in the normal subjects. Basal enteroglucagon levels were significantly increased in chronic pancreatitis but response to orla glucose and arginine infusion were little different from those seen in the normal subjects.