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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The starvation-related changes of glucose and maltose absorption were shown to be unrelated to absorption of sucrose and lactose. The glucose and maltose transport responds synchronously to starvation and refeeding. The total reduction of the mice body mass after refeeding occurred in 48 hrs. The effect of a preliminary load of the gastrointestinal tract on the transport rate in enzyme-transport system, is discussed.
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PMID:[The effect of starvation on carbohydrate transport in the mouse and rat small intestine]. 840 58

Nutritionists, including those involved in famine relief, have learned in the last 25 years that certain deficiency diseases arise from the high protein foods used to rehabilitate starving populations. Other, sometimes inappropriate relief foods starving populations. Other, sometimes inappropriate relief foods include unprocessed or inappropriate grains and unfortified dry skimmed milk. Yet, relief workers do not always receive the most appropriate food for distribution to certain populations. Millions of dollars are appropriated to protect relief supplies for starving people in Somalia, but money is not spent to develop and evaluate simple foods that might save the lives of starving people. There are several items relief agencies and governments should consider when deciding on the most appropriate foods to prevent starvation in famine situations. During kwashiorkor, intestinal mucous produce grossly defective cells, resulting in considerable lactose malabsorption. Thus, using milk to rehabilitate people, especially children, poses a considerable hazard. High carbohydrate diets to rehabilitate starving people can cause gross edema and fatal congestive heart failure. Generally, clinically apparent vitamin or mineral deficiencies do not occur during famines, because the amount of vitamins or minerals needed to small to maintain a very shrunken body. Yet, when the body demand increases as a result of a rehabilitation diet poor in vitamins and minerals but high in protein or calories, clinical deficiency symptoms emerge, e.g., pellagra in Mozambique. Common food combinations used in relief situations consists of corn, soy, and milk fortified with vitamins and minerals (Bal'ahar mixture, India). Both mixtures require the addition of vegetable oils to make it easier for infants and small children to digest the mixtures.
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PMID:Starvation in the modern world. 845 Aug 73

Basic features of regulation of expression of the genes encoding the cellulases of the filamentous fungus Trichoderma reesei QM9414, the genes cbh1 and cbh2 encoding cellobiohydrolases and the genes egl1, egl2 and egl5 encoding endoglucanases, were studied at the mRNA level. The cellulase genes were coordinately expressed under all conditions studied, with the steady-state mRNA levels of cbh1 being the highest. Solka floc cellulose and the disaccharide sophorose induced expression to almost the same level. Moderate expression was observed when cellobiose or lactose was used as the carbon source. It was found that glycerol and sorbitol do not promote expression but, unlike glucose, do not inhibit it either, because the addition of 1 to 2 mM sophorose to glycerol or sorbitol cultures provokes high cellulase expression levels. These carbon sources thus provide a useful means to study cellulase regulation without significantly affecting the growth of the fungus. RNA slot blot experiments showed that no expression could be observed on glucose-containing medium and that high glucose levels abolish the inducing effect of sophorose. The results clearly show that distinct and clear-cut mechanisms of induction and glucose repression regulate cellulase expression in an actively growing fungus. However, derepression of cellulase expression occurs without apparent addition of an inducer once glucose has been depleted from the medium. This expression seems not to arise simply from starvation, since the lack of carbon or nitrogen as such is not sufficient to trigger significant expression.
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PMID:Regulation of cellulase gene expression in the filamentous fungus Trichoderma reesei. 909 27

The hfb2 gene encoding the hydrophobin HFBII of the filamentous fungus Trichoderma reesei was isolated by heterologous hybridization using the vegetative hydrophobin I, hfb1, gene of T. reesei as a probe. The hfb2 gene codes for a typical fungal secreted hydrophobin of 71 amino acids containing eight cysteine residues. The amino acid similarity towards HFBI is 69%. The HFBII protein was isolated from the fungal spores by extraction with trifluoroacetic acid/acetonitrile solution, and by bubbling from the lactose-based culture medium. Expression of the hfb1 and hfb2 genes is divergent. hfb1 expression was only observed in vegetative cultures on glucose-containing and sorbitol-containing media. It was not expressed on media containing complex plant polysaccharides, cellulose, xylan, cellobiose or lactose, whereas hfb2 was highly expressed in vegetative cultures on these media. Expression of hfb2 was also strongly induced by N and C starvation, by light and in conidiating cultures.
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PMID:Differential expression of the vegetative and spore-bound hydrophobins of Trichoderma reesei--cloning and characterization of the hfb2 gene. 934 97

The general stress sigma factor sigmaS (RpoS) of Escherichia coli is strongly induced in response to glucose starvation. This increase in the cellular sigmaS level is due to stabilization of sigmaS, which under non-stress conditions is subject to rapid proteolysis. In the present study, it is demonstrated that sigmaS is also induced during the diauxic shift from glucose to lactose, i.e., under conditions of glucose exhaustion in the presence of another, less-preferred carbon source that eventually gets utilized. This sigmaS induction, which is due to stabilization, is transient and precedes the induction of beta-galactosidase. In parallel, sigmaS-dependent genes are transiently activated, as was shown here for osmY. Although sigmaS can mediate transcription of lacZ in vitro, sigmaS does not contribute to the induction of beta-galactosidase during the diauxic lag phase. Rather, the induction of sigmaS and the general stress response during the diauxic shift plays the role of a rapidly activated emergency system, which is shut off again as soon as the cells are able to cope with the stress situation by utilizing a more specific and more economical system.
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PMID:The general stress sigma factor sigmaS of Escherichia coli is induced during diauxic shift from glucose to lactose. 982 28

Two strains of Lactococcus lactis subsp. lactis were used to determine the influence of lactose and arginine on viability and amino acid use during carbohydrate starvation. Lactose provided energy for logarithmic-phase growth, and amino acids such as arginine provided energy after carbohydrate exhaustion. Survival time, cell numbers, and ATP concentrations increased with the addition of arginine to the basal medium. By the onset of lactose exhaustion, the concentrations of glycine-valine and glutamate had decreased by as much as 67% in L. lactis ML3, whereas the serine concentration increased by 97% during the same period. When no lactose was added, the concentrations of these amino acids remained constant. Similar trends were observed for L. lactis 11454. Without lactose or arginine, L. lactis ML3 was nonculturable on agar but was viable after 2 days, as measured by fluorescent viability stains and intracellular ATP levels. However, L. lactis 11454 without lactose or arginine remained culturable for at least 14 days. These data suggest that lactococci become viable but nonculturable in response to carbohydrate depletion. Additionally, these data indicate that amino acids other than arginine facilitate the survival of L. lactis during carbohydrate starvation.
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PMID:Influence of carbohydrate starvation and arginine on culturability and amino acid utilization of lactococcus lactis subsp. lactis. 992 98

Lovastatin is a secondary metabolite produced by Aspergillus terreus. A chemically defined medium was developed in order to investigate the influence of carbon and nitrogen sources on lovastatin biosynthesis. Among several organic and inorganic defined nitrogen sources metabolized by A. terreus, glutamate and histidine gave the highest lovastatin biosynthesis level. For cultures on glucose and glutamate, lovastatin synthesis initiated when glucose consumption levelled off. When A. terreus was grown on lactose, lovastatin production initiated in the presence of residual lactose. Experimental results showed that carbon source starvation is required in addition to relief of glucose repression, while glutamate did not repress biosynthesis. A threefold-higher specific productivity was found with the defined medium on glucose and glutamate, compared to growth on complex medium with glucose, peptonized milk, and yeast extract.
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PMID:Lovastatin biosynthesis by Aspergillus terreus in a chemically defined medium. 1137 68

In a system described by Cairns and Foster, starvation of a particular leaky lac mutant (lacIZ33) in the presence of lactose appears to direct mutation in non-growing cells to sites that allow growth (adaptive mutation). This behaviour requires that the lac operon be located on an F' plasmid. This position effect was investigated by placing the mutant lac operon at many sites in the genome of Salmonella enterica (Typhimurium; LT2) and testing reversion behaviour. Genomic position did not affect reversion during non-selective growth. When lac was at any of 550 chromosomal sites, starvation caused little or no enhancement of reversion. In the 28 strains with the lac on Salmonella's conjugative plasmid (pSLT), selection enhanced reversion strongly, just as seen for strains with lac on an F' plasmid. In 46 strains, the lac operon was inserted within a small chromosomal duplication, and selection stimulated RecA-dependent partial reversion by simple amplification (about 8x) of the mutant lac region. The position of lac on a conjugative plasmid is important to reversion because it allows more frequent gene duplication and amplification. These events are central to growth and reversion under selection because they increase the number of replicating lac alleles within each developing revertant clone.
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PMID:The effect of genomic position on reversion of a lac frameshift mutation (lacIZ33) during non-lethal selection (adaptive mutation). 1201 Apr 95

Escherichia coli strain MG1655 was chosen for sequencing because the few mutations it carries (ilvG rfb-50 rph-1) were considered innocuous. However, it has a number of growth defects. Internal pyrimidine starvation due to polarity of the rph-1 allele on pyrE was problematic in continuous culture. Moreover, the isolate of MG1655 obtained from the E. coli Genetic Stock Center also carries a large deletion around the fnr (fumarate-nitrate respiration) regulatory gene. Although studies on DNA microarrays revealed apparent cross-regulation of gene expression between galactose and lactose metabolism in the Stock Center isolate of MG1655, this was due to the occurrence of mutations that increased lacY expression and suppressed slow growth on galactose. The explanation for apparent cross-regulation between galactose and N-acetylglucosamine metabolism was similar. By contrast, cross-regulation between lactose and maltose metabolism appeared to be due to generation of internal maltosaccharides in lactose-grown cells and may be physiologically significant. Lactose is of restricted distribution: it is normally found together with maltosaccharides, which are starch degradation products, in the mammalian intestine. Strains designated MG1655 and obtained from other sources differed from the Stock Center isolate and each other in several respects. We confirmed that use of other E. coli strains with MG1655-based DNA microarrays works well, and hence these arrays can be used to study any strain of interest. The responses to nitrogen limitation of two urinary tract isolates and an intestinal commensal strain isolated recently from humans were remarkably similar to those of MG1655.
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PMID:Physiological studies of Escherichia coli strain MG1655: growth defects and apparent cross-regulation of gene expression. 1294 14

The freeze-drying tolerance of Pseudomonas chlororaphis, an antifungal bacterium used as biocontrol agent was investigated. P. chlororaphis is freeze-drying sensitive and the viability drops more than 3 log units in the absence of protective freeze-drying medium. Of the freeze-drying media tested, lactose, sucrose, trehalose, glutamate, sucrose with glutamate, skimmed milk, and skimmed milk with trehalose, skimmed milk gave the lowest survival (0.6+/-0.2%) and sucrose the highest (6.4+/-1.2%). Cellular accumulation of sucrose from the freeze-drying medium and the protective effect of sucrose were dependent on sucrose concentration. The effect of initial cell concentration, from 1 x 10(7) to 5 x 10(10) CFU/ml, on survival after freeze-drying was studied for carbon starved cells with sucrose as freeze-drying medium. The highest freeze-drying survival values, 15-25%, were obtained for initial cell concentrations between 1 x 10(9) and 1 x 10(10) CFU/ml. For cell concentrations outside this window more than 10 times lower survival values were observed. P. chlororaphis was cultivated to induce stress response that could confer protection against freeze-drying inactivation. Carbon starvation and, to a lesser extent, heat treatment enhanced freeze-drying tolerance. By combining optimal cell concentration, optimal sucrose concentration and carbon starvation the survival after freeze-drying was 26+/-6%.
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PMID:Optimisation of initial cell concentration enhances freeze-drying tolerance of Pseudomonas chlororaphis. 1296 9


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