Lipid peroxidation in plumbagin administered rats

Plumbagin was administered to rats at a concentration of 1,2,4,8 and 16 mg per kg body weight. After 24 h lipid peroxide levels were found to decrease in subcellular fractions of liver. Plumbagin inhibited ascorbate and nicotinafde adenine dinucleotide phosphate (reduced) dependent lipid peroxidation but was without any effect on cumene hydroperoxide dependent lipid peroxidation. Injection of 16 mg of plumbagin per kg body weight was found to decrease liver total reduced glutathione and also fcrosomal glucose-6-phosphatase. The results are discussed with reference to the anti- and prooxidant properties of plumbagin.     

Synthesis of ribulose 1,5-bisphosphate carboxylase by isolatedSorghum mesophyll chloroplasts

Chloroplasts isolated fromSorghum vulgare are active in light-dependent, organelle protein synthesis. Intact chloroplasts can use light as an energy source; photosynthetically inactive chloroplasts require the addition of ATP for this protein synthesis. Preincubation of chloroplasts in light at 25°C for 1 h depleted the endogenous templates completely; such preincubated chloroplasts translated exogenously added heterologous templates efficiently. When total cellular RNA fromChlorella protothecoides, a C₃ plant, was used as template for translation in a cell-free light-dependent system of isolated mesophyll chloroplasts fromSorghum vulgare, a C₄ type plant, polypeptides of 55 kDa (large subunit) and 15 kDa (small subunit) were detectable in the fluorographic profile of the newly synthesized proteins; these polypeptides were absent in the products obtained with endogenous RNA. Evidence for the fidelity of the system was obtained by immunological analysis of ribulose 1, 5-bisphosphate carboxylase obtained by the translation ofChlorella cellular RNAs.     

Induction and accumulation of phytoalexins in cowpea roots infected with a mycorrhizal fungusGlomus fasciculatum and their resistance toFusarium wilt disease

The interaction of a vesicular-arbuscular mycorrhizal fungusGlomus fasciculatum with a wilt-causing soil borne pathogen,Fusarium oxysporum, was studied in cowpea (Vigna unguiculata). It was found that pre-establishment by vesicular-arbuscular mycorrhizal fungus reduced the colonization of the pathogen and the severity of the disease, as determined by reduction in vascular discolouration index. In mycorrhizal plants, the production of phytoalexin compounds was always higher than in the nonmycorrhizal plants. There appeared to be a direct correlation between the concentration of the phytoalexins and the degree of mycorrhizal association. Three different compounds withR _f values of 0.23 (I), 0.17 (II) and 0.11 (III) were obtained from mycorrhizal plants. Similar compounds were also found to be induced by an abiotic elicitor CuSO₄. The first compound was identified as an isoflavonoid, daidzein and the other two remain to be identified. These compounds were checked for their antifungal activityin vitro. The germination of conidial spores ofFusarium oxysporum was strongly inhibited by the compound III than the other two. It is argued that the production of phytoalexin compounds in mycorrhizal plant could be one of the mechanisms imparting tolerance of the plants to wilt disease.     

Production of pectinases by Aspergillus niger in solid state fermentation at high initial glucose concentrations

Exopectinase (exo-p) and endopectinase (endo-p) production by Aspergillus niger CH4 in solid state culture was studied at initial glucose concentrations of 100, 250, 350 and 450 g/l. The highest activity of exo-p (35 U/g) was produced at 72 and 120 h in the medium containing 100 and 250 g glucose/l, respectively. The maximum endo-p activity (9 U/g) was produced at 72 h in the medium with 250 g glucose/l. The reduction in pectinase production at 350 and 450 g/l initial glucose concentration was due neither to repression of the synthesis of the enzyme nor to the glucose consumption rate of the strain but due to a drastic drop in pH of the medium.S. Solis-Pereyra, E. Favela-Torres, M. Gutiérrez-Rojas, G. Saucedo-Castañeda and G. Viniegra-González are with the Departamento de Biotecnologia, Universidad Autónoma Metropolitana, A.P. 55-535, C.P. 09340, México D.F., México; S. Roussos is with the Laboratoire de Biotechnologie, ORSTOM, B.P. 5045, 34032, Montpellier Cedex, France, and P. Gunasekaran is with the Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625-021, India.     

Influence of carbon and nitrogen sources on glutathione catabolic enzymes inCandida albicans during dimorphism

The effect of carbon sources, glucose and sucrose, and nitrogen sources such as ammonia, glutamate andl-citrulline on the activities of glutathione metabolic enzymes has been studied. Yeast and mycelial cells were used to identify changes in activity levels of glutathione reductase (GSSGR), glutathione transferase (GST), glutathione peroxidase (GPX) and -glutamyl transpeptidase (GGT). Enzyme activities from cells grown in sucrose media were lower than in glucose media regardless of the enzyme tested, morphological form, or the growth interval. In all enzymes except GST, activity was higher in yeast form than in mycelia, regardless of nitrogen source, with lower activity from 24 to 72 h than at 96 h. In citrulline media, yeast form showed the maximum GST, GGT, and GPX activity. In ammonia-amended media, mycelia showed maximum activity in GGT, whereas in glutamate media, mycelia showed the maximum activity in GST. Also, the type of nitrogen source had no effect on GPX activity in the mycelial form. Finally, changing the nitrogen source showed no significant effect on GSSGR activity, either in the yeast or mycelial form.     

Purification and properties of glutamine synthetase from Nocardia asteroides

Glutamine synthetase (GS, EC 6.3.1.2) from Nocardia asteroides was purified to homogeneity by ammonium sulfate precipitation, Sephadex G-150, and DEAE-Sepharose chromatography. The native molecular weight of the purified enzyme was determined to be 720 kDa. SDS-PAGE analysis of the purified preparation revealed a single band corresponding to 59 kDa, indicating the possible presence of 12 identical subunits. The divalent cations Mn^2- and Mg²⁺ were found to be essential for optimal transferase and biosynthetic activity, respectively. The optimal pH and temperature for both activities of the enzyme were found to be 7.2 and 50°C. Amino acids such as l-alanine, glycine, and aspartate inhibited the GS activity. The K _m values for the substrates of the biosynthetic reaction ATP, glutamate, and ammonium chloride were found to be 400 m, 7.7mm, and 200 m, respectively. Addition of ammonium chloride to the nitrogen-limited culture resulted in a decrease of GS transferase and biosynthetic activities. Phosphodiesterase treatment of the extract from ammonia-shocked cultures showed an increase in GS transferase activity. The results indicate the possible regulation of GS by covalent modification.     

A simple liquid medium for chlamydospore formation in Candida albicans

A new, relatively simple and inexpensive liquid medium was devised to produce all structural forms ofC. albicans. Optimum conditions to induce the yeast cells, germ tubes, pseudohyphae and chlamydospores along with the methods to obtain them are described.Supported in part by Grant CA 20917, National Cancer Institute, National Institutes of Health and ALSAC.     

Structure and species distribution in Coringa mangrove forest,Godavari Delta,Andhra Pradesh,India

Coringa mangrove forest is located in the Godavari delta, Andhra Pradesh, India. The mangrove community consisted of more than 13 species of mangrove and other plants in the present study area. The following three dominant mangrove plants,Avicennia marina, Excoecaria agallocha andSonneratia apetala were found to be present on the banks of a major channel of the Godavari river running through the forest. The structure and species distribution of mangrove, in the Channel Nagathana Kalaya has been described. The area behind the belt consisting ofAcanthus ilicifolius andMyriostachya wightiana is generally colonized byE. agallocha andA. marina. The zone has been called theAvicennia andExcoecaria zone. Adjacent to this zone species likeAegiceras corniculatum andA. officinalis were the common species. In the flat clayey soil,Suaeda maritima was found to grow. In areas of high elevation, devoid of inundation of tidal seawater during the high tidal period, species such asM. wightiana andAcanthus were found to colonize both the banks of the channels.An analysis of species diversity, indicated a definite trend in the distribution of mangrove from the mouth of the estuarine region to the inland waters.The levels of atmospheric pollutants such as sulphur dioxide (SO₂), oxides of nitrogen (NO_x), ammonia (NH₃) and suspended particle matter (SPM) were within the legal limits.