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Query: CAS:7440-44-0 (Carbon)
 10,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Azotobacter vinelandii (ATCC 12837) became competent to be transformed by exogenous deoxyribonucleic acid towards the end of exponential growth. Competence in wild-type and nitrogenase auxotrophic (nif-) strains was repressed by the addition of ammonium salts or urea to the transformation medium. Transformation of wild-type cells and nif- strains was optimal on nitrogen-free or nitrogen-limiting medium, respectively. Transformation of wild-type cells also was enhanced when the transformation medium had low molydbate content. During the development of competence, nitrogen was growth limiting, whereas carbon (glucose) was in excess. Carbon source shift-down was not effective in inducing competence. Shifting glucose-grown wild-type cells to medium containing 0.2% beta-hydroxybutyrate initiated encystment and also induced competence. The addition of glucose to this medium blocked encystment and early competence induction and reduced the transformation frequency to the basal level. Cyclic adenosine 3',5'-monophosphate induced competence in wild-type nitrogen-fixing cells and increased the transformation frequency 1,000-fold over the basal level. Exogenous cyclic adenosine 3',5'-monophosphate however, did not reverse nitrogen repression of competence in ammonia-grown wild-type or nif- strains.
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PMID:Control of transformation competence in Azotobacter vinelandii by nitrogen catabolite derepression. 17 41

Carbon/nitrogen ratio as a factor for sporulation, expressed in terms of magnitude of population variation of macroconidia and microconidia in the cultures of Eusarium oxysporum Schlecht ex. Fr., Fusarium moniliforme v. subglutinans Wr. and Rg., and of chlamydospores (only in Fusarium oxysporum) was investigated. It has been found that the amount of carbon source shapes the course of macro- and micro. conidial production in a linear fashion, being enhanced parallel to the increase in its amount-Nitrogen level, limiting proliferation and effectively diminishing the macro- and micro-conidial population, varies for the two species, namely Fusarium oxysporum and Fusarium moniliforme v-subglutinans. For chlamydomspore production, higher carbon and still higher nitrogen concentration favours profuse proliferation in case of Fusarium oxysporum.
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PMID:Comparative studies with regard to the influence of carbon and nitrogen ratio on sporulation in Fusarium oxysporum and Fusarium moniliforme v. subglutinans. 54 20

Valine, leucine, and isoleucine were extracted by the lactating bovine mammary gland in excess of outputs in milk protein. Carbon-14 uniformly labeled L-valine, L-leucine or L-isoleucine were catabolized when incubated in vitro with lactating bovine mammary tissue slices. The pathways of degradation of these amino acids by mammary tissue appear to be those common to other tissues. These amino acids represent a potential source of energy to the mammary gland as well as a source of carbon and alpha-amino nitrogen for synthesis of nonessential amino acids.
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PMID:Valine, leucine, and isoleucine metabolism by lactating bovine mammary tissue. 56 75

Carbon-13 and proton nuclear magnetic resonance (NMR) spectra have been recorded for porphyrins, zinc porphyrins, and iron(III) porphyrin complexes in aqueous media. Spectra of porphyrin-c and hemin-c confirm the structure with thioether linkages at positions alpha to the porphyrin ring. The pattern of NMR isotropic shifts has implications regarding electron transfer in cytochrome-c. Free-base porphyrin-c and meso-substituted porphyrins have been examined for pyrrole nitrogen-hydrogen tautomerism and possible aggregation in aqueous solution. Zinc porphyrin 13C NMR spectra were recorded in order to provide diamagnetic references for paramagnetic iron(III) derivatives. Low-spin iron(III) porphyrin-biscyano complexes in aqueous solution exhibit NMR isotropic shift patterns similar to those previously observed for related compounds in non-aqueous media. The first 13C NMR spectra are reported for mu-oxo-bridged iron(III) porphyrin dimers. A partially resolved spectrum of a high-spin iron(III) porphyrin has also been obtained. Patterns of 13C and proton isotropic shifts are compared, and unpaired spin delocalization mechanisms for 13C resonances are discussed in a qualitative manner.
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PMID:Carbon-13 and proton nuclear magnetic resonance spectroscopy of water-soluble porphyrins and metalloporphyrins. 68 73

Carbon-nitrogen ratio experiments indicate that limiting nutrition not only hinders Penicillium stoloniferum host proliferation but reduces total PsV-F and PsV-S virus replication. Results of C-N experiments show a pH-induced autolysis and virus release at minimal C levels. Maximal PsV-F levels and biomass were obtained with glucose and sucrose as C sources. Oleic acid also yielded high biomass and PsV-F yields. Yeast extract was an excellent N source; 2.83 g dry weight biomass and 87 A260 units PsV-F after 96 h of growth. Other nitrogen sources, including amino acids, supported only minimal growth and virus replication. The autolysis phenomenon is pH, not viral-induced. High C and N will support maximal growth and unrestricted virus replication with no cellular lysis. Under low C growth conditions, the replication of PsV-S is favored coupled with high pH and autolysis.
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PMID:Mycoviruses of Penicillium stoloniferum: influence of carbon-nitrogen nutrition upon replication. 68 2

Three isolates, a Pseudomonas sp., a Bacillus sp. and an Arthrobacter sp., which had been isolated from a meadow soil at Devon Island, Canada, were subjected to starvation under varying conditions. The viabilities of the three isolates during starvation for 30 days in a carbon-free medium was assessed after the organisms had been grown continuously at varying rates in carbon- and nitrogen-limited media at 5 and 15 degrees C. Pseudomonas M216 was the most resistant to starvation stress, Bacillus M153 the least, and Arthrobacter M51 was intermediate in its response. Cells grown and starved at 5 degrees C survived longer than those at 15 degrees C. Carbon-limited Bacillus and Arthrobacter cells grown at high rates prior to starvation survived longer than those grown slowly, while in nitrogen-limited Arthrobacter the reverse was observed. The pattern of endogenous metabolism of the three isolates during starvation at 15 degrees C for 10 days was similar to that observed in other organisms. Levels of endogenous substrates such as carbohydrate and protein showed a rapid decrease in the initial 20 h of starvation, followed by a gradual decline over the remainder of the starvation period. The rates of endogenous metabolism of the isolates were positively correlated with their survival rates during starvation.
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PMID:Effect of starvation on survival of three bacterial isolates from an arctic soil. 74 9

The response of the marine Vibrio sp. strain S14 to starvation for carbon, nitrogen, or phosphorus and to simultaneous depletion of all these nutrients (multiple-nutrient starvation) was examined with respect to survival, stress resistance, quantitative and qualitative alterations in protein and RNA synthesis, and the induction of the stringent control. Of the conditions tested, carbon starvation and multiple-nutrient starvation both promoted long-term starvation resistance and a rapid induction of the stringent control, as deduced from the kinetics of RNA synthesis. Carbon- and multiple-nutrient-starved cells were also found to become increasingly resistant to heat, UV, near-UV, and CdCl2 stress. Nitrogen- and phosphorus-starved cells demonstrated a poor ability to survive in the presence of carbon and did not develop a marked resistance to the stresses examined. The carbon, nitrogen, and phosphorus starvation stimulons consisted of about 20 proteins each, while simultaneous starvation for all the nutrients elicited an increased synthesis of 42 polypeptides. Nine common proteins were found to be induced regardless of the starvation condition used and were tentatively termed general starvation proteins. It was also demonstrated that the total number of proteins induced in response to multiple-nutrient starvation was not a predictable sum of the different individual starvation stimulons. Multiple-nutrient starvation induced 14 proteins which were not detected at increased levels of expression in response to individual starvation conditions. Furthermore, four out of five phosphorus starvation-specific polypeptides were not induced during simultaneous starvation for phosphorus, nitrogen, and carbon. The results are discussed in light of the physiological alterations previously described for Vibrio sp. strain S14 cells starved for carbon, nitrogen, and phosphorus simultaneously.
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PMID:Survival, stress resistance, and alterations in protein expression in the marine vibrio sp. strain S14 during starvation for different individual nutrients. 137 61

We found that cells of Saccharomyces cerevisiae have an elevated level of the NAD-dependent glutamate dehydrogenase (NAD-GDH; encoded by the GDH2 gene) when grown with a nonfermentable carbon source or with limiting amounts of glucose, even in the presence of the repressing nitrogen source glutamine. This regulation was found to be transcriptional, and an upstream activation site (GDH2 UASc) sufficient for activation of transcription during respiratory growth conditions was identified. This UAS was found to be separable from a neighboring element which is necessary for the nitrogen source regulation of the gene, and strains deficient for the GLN3 gene product, required for expression of NAD-GDH during growth with the activating nitrogen source glutamate, were unaffected for the expression of NAD-GDH during growth with activating carbon sources. Two classes of mutations which prevented the normal activation of NAD-GDH in response to growth with nonfermentable carbon sources, but which did not affect the nitrogen-regulated expression of NAD-GDH, were found and characterized. Carbon regulation of GDH2 was found to be normal in hxk2, hap3, and hap4 strains and to be only slightly altered in a ssn6 strain; thus, in comparison with the regulation of previously identified glucose-repressed genes, a new pathway appears to be involved in the regulation of GDH2.
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PMID:Physiological and genetic analysis of the carbon regulation of the NAD-dependent glutamate dehydrogenase of Saccharomyces cerevisiae. 165 57

Effects of Hg and Zn on in situ nitrogen fixation, autotrophic index, pigment diversity, 14CO2 uptake, and change in algal community structure of Ganges water have been studied for the first time using CEPEX chambers in aquatic ecosystem of India. A concentration-dependent decrease in in situ nitrogenase activity of Ganges water with Hg and Zn has been noticed. No ethylene production was observed at 0.8 microgram/ml of Hg. However, an increase in the autotrophic index was observed in CEPEX enclosures treated with Hg and Zn. The AI value was maximum at 0.8 microgram/ml Hg after an incubation of 15 days. An increase in pigment diversity also followed the pattern of AI with the test metals used. Inhibition of 14CO2 uptake of phytoplankton of Ganges water was maximum at 0.8 microgram/ml Hg (79%) followed by Zn (69%). Carbon fixation showed an increase for 1 hr, after which no appreciable change was noticed. Maximum inhibition of algal number was observed at 0.8 microgram/ml Hg followed by 8.0 micrograms/ml of Zn in the CEPEX chamber. Members of Chlorophyceae showed more tolerance than Cyanophyceae and Bacillariophyceae. The filamentous forms were more tolerant to Hg and Zn. In contrast, unicellular forms were more sensitive to Hg. The test of significance (ANOVA) showed that metal-induced variations in pigment diversity, the autotrophic index, and the 14CO2 uptake were highly significant (P less than 0.001).
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PMID:Employment of CEPEX enclosures for monitoring toxicity of Hg and Zn on in situ structural and functional characteristics of algal communities of River Ganga in Varanasi, India. 198 Apr 58

In this paper some radioanalytical methods will be described for assessing the contents of various elements in the human body. In vivo methods are necessary for this problem. Protein content can be estimated by means of in vivo measurements of nitrogen, bone minerals by means of the total body content of calcium. Fat contains a high concentration of carbon. Carbon in fat can be estimated and from this the total body fat can be calculated. Toxic elements such as lead, cadmium and mercury are assessed by in vivo measurements, both related to occupationally exposed workers and to members of the public.
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PMID:Experiences in the field of elemental analysis in vivo. 219 89


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