Mycotoxigenic infestation in samples of cereal straw from Bihar, India

A survey of different types of cereal straw samples viz. paddy, maize and wheat, from Bihar State, India, was conducted in order to examine the mould flora and mycotoxin contamination. Out of 170 samples examined for mould flora,Aspergillus flavus group of fungi had highest level of incidence followed byA niger. Isolates ofA flavus, A ochraceus, Fusarium verticillioides andPenicillium citrinum were screened for their mycotoxins producing abilities. Out of 75, 63 and 68 isolates ofA flavus group obtained from stored straw of paddy, maize and wheat samples, respectively, 27 (36%), 14 (22%) and 24 (35%) were found to be toxigenic which produced different combinations of aflatoxins in different concentrations. The percentage toxigenicity was comparatively lower in the isolates of other mycotoxigenic fungi from all types of samples. Out of 222 samples of straw analysed for natural occurrence of different mycotoxins, besides the aflatoxins present, zearalenone, ochratoxin A and citrinin were also recorded alone or as co-contaminants. A conducive climate together with the socioeconomic conditions of this region are important determinants for the high incidence of mycotoxins in cereal straw samples.     

Homologies of the adductor mandibulae muscles in Tetraodontiformes as indicated by nerve branching patterns

Homologies of the adductor mandibulae muscles in eight families of Tetraodontiformes were hypothesized from the branching patterns of ramus mandibularis trigeminus. Insertions of the muscles to the upper or lower jaw were weak indicators of homology, migrations of the sites occurring frequently in A1, A2, A2, and A3. In monacanthids, tetraodontids, and diodontids, A1 tended to be split into numerous subsections, whereas in aracanids and ostraciids, A3 was highly developed, comprising three or four subsections. In tetraodontids, A2 was found to be a composite of A1 subsection and A2. The methods of and limits to applying nerve branching patterns to muscle homology are discussed. A new naming system that reflects both muscle homologies and insertions is proposed.     

Exogenously applied ascorbic acid ameliorates detrimental effects of NaCl and mannitol stress in Vicia faba seedlings

The adverse effects of either NaCl or mannitol on growth, nitrogen content, and antioxidant system in Vicia faba seedlings were investigated. The role of exogenous ascorbic acid in increasing resistance to these stressors was also evaluated. Thus, with an increase in concentration of either NaCl or mannitol in culture media, a progressively greater significant decrease in percentage germination, in growth parameters, and in nitrogen constituents of the germinating beans, was observed. On the other hand, amide-, nitrate-, and total soluble-N contents appeared to show a progressive significant increase. Exogenous addition of ascorbic acid (4 mM) to the stressful media induced a pronounced significantly increased percentage germination and the growth attributes, whereas nitrogen constituents were variably changed in relation to values maintained in beans treated with either NaCl or mannitol. Furthermore, exogenous addition of ascorbic acid to NaCl or mannitol media induced a significant increase in the contents of ascorbate and glutathione and enzymatic antioxidant activities, in particular, in beans treated with the three highest concentrations of NaCl or mannitol, throughout the period of the experiments (12 days). Thus, ascorbic acid ameliorates the adverse effects of the stressful media; the magnitude of amelioration being a function of the type and the concentration of the stressful agent as well as of the duration of treatment. The importance of the above-mentioned changes in growth and metabolism to stress tolerance in broad bean is discussed.     

In vitro fertilization of goat oocytes

Experiments were carried out to achieve fertilization (IVF) and initial embryonic development of goat oocytes in vitro. Oocyte/cumulus complexes were recovered from large follicles (greater than 7 mm) of hormonally treated doses and from 1-6-mm follicles of ovaries from hormonally superstimulated and nontreated goats. Three different sperm treatment/IVF media were used: defined medium (Brackett and Oliphant, Biol Reprod 1975; 12:260-274) with modifications (mDM); TALP (Bavister and Yanagimachi, Biol Reprod 1977; 16:228-237), as modified by Parrish et al. (Theriogenology 1986; 25:591-600), i.e. modified TALP (mTALP); and HEPES-buffered M199 with modifications (mH-M199). Immature oocytes (from 1-6 mm, small antral follicles) were cultured for in vitro maturation (IVM) in M199 buffered with bicarbonate and with modifications including supplementation with 20% (v/v) goat serum (mB-M199) with either (a) 100 micrograms LH/ml, (b) 5 micrograms FSH/ml, or (c) no added gonadotropin control. Insemination of (in vivo or in vitro) matured oocytes was performed with swim-up separated and heparin-treated freshly ejaculated sperm; additionally, caffeine was included in the mDM treatment. Use of mDM yielded better results than mTALP or mH-M199 (p less than .05). Results with oocytes after IVM were significantly better than those obtained with oocytes matured in vivo (68.4% vs. 45.5%, p less than 0.05). Presence of LH or FSH during oocyte maturation improved both the IVM and IVF results over those of the control (p less than 0.05). The highest proportion of fertilized oocytes (fertilization rate) was achieved by combining the use of mDM for sperm and IVF with IVM in the presence of LH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Conformation and activity of chloroplast coupling factor exposed to low chemical potential of water in cells

(1) Photophosphorylation, fCa²⁺-ATPase and Mg²⁺-ATPase activities of isolated chloroplasts were inhibited 55–65% when the chemical potential of water was decreased by dehydrating leaves to water potentials (ψ_w) of ?25 bars before isolation of the plastids. The inhibition could be reversed in vivo by rehydrating the leaves.(2) These losses in activity were reflected in coupling factor (CF₁) isolated from the leaves, since CF₁ from leaves with low ?_w had less Ca²⁺-ATPase activity than control CF₁ and did not recouple phosphorylation in CF₁-deficient chloroplasts. In contrast, CF₁ from leaves having high ?_w only partially recoupled phosphorylation by CF₁-deficient chloroplasts from leaves having low ?_w. This indicated that low ?_w affected chloroplast membranes as well as CF₁ itself.(3) Coupling factor from leaves having low ψ_w had the same number of subunits, and the same electrophoretic mobility, and could be obtained with the same yields as CF₁ from control leaves. However, direct measurements of fluorescence polarization, ultraviolet absorption, and circular dichroism showed that CF₁ from leaves having low ?_w differed from control CF₁. The CF₁ from leaves having low ?_w also had decreased ability to bind fluorescent nucleotides (?-ATP and ?-ADP).(4) Exposure of isolated CF₁ to low ?_w in vitro by preincubation in sucrose-containing media inhibited the Ca²⁺-ATPase activity of the protein in subsequent assays without sucrose. Inclusion of 5 or 10 mM Mg²⁺ in the preincubation medium markedly inhibited Ca²⁺-ATPase activity.(5) These results show that CF₁ undergoes changes in cells which alter its phosphorylating ability. Since low cell ?_w changed the spectroscopic properties but not other protein properties of CF₁, the changes were most likely caused by altered conformation of the protein. This decreased the binding of nucleotides and, in turn, photophosphorylation. The inhibition of ATPase activity in CF₁ in vitro at low ?_w and high ion concentration mimicked the change in activity seen in vivo.     

Synthesis of biologically active steroid derivatives by the utility of Lawesson's reagent

Steroid derivatives V, VI, VII and VIII reacted with Lawesson's reagent (LR) to produce spiro-oxazaphosphole-4',17-androstene derivative XI, diazaphospholoandrostane XIV and the thionated derivatives XVI and XVII, respectively. The structures of the new compounds were confirmed by analytical and spectroscopic evidence. A mechanism accounting for the formation of the new compounds was given. The in vitro antimicrobial activity of the new compounds were tested.