Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Conditions were investigated that promote the formation of 'non-culturable' (NC) cells of Mycobacterium (Myc.) smegmatis in stationary phase. After cultivation in a rich medium, or under conditions that may be considered optimal for bacterial growth, or starvation for carbon, nitrogen or phosphorus, bacteria failed to enter a NC state. However, when grown under suboptimal conditions, resulting in a reduced growth rate or maximal cell concentration (e.g. in modified Hartman's-de Bont medium), bacteria adopted a stable NC state after 3-4 days incubation in stationary phase. Such conditions are not specific as purF and devR mutants of Myc. smegmatis also showed (transient) loss of culturability following growth to stationary phase in an optimized medium, but under oxygen-limited conditions. The behaviour of the same mutants in oxygen-sufficient but nutrient-inappropriate medium (modified Hartman's-de Bont medium) was similar to that of the wild-type (adoption of a stable NC state). It is hypothesized that adoption of a NC state may represent an adaptive response of the bacteria, grown under conditions when their metabolism is significantly compromised due to the simultaneous action of several factors, such as usage of inappropriate nutrients or low oxygen availability or impairment of a particular metabolic pathway. NC cells of wild-type Myc. smegmatis resume growth when transferred to a suitable resuscitation medium. Significantly, resuscitation was observed when either recombinant Rpf protein or supernatant derived from a growing bacterial culture was incorporated into the resuscitation medium. Moreover, co-culture with Micrococcus (Mcc.) luteus cells (producing and secreting Rpf) also permitted resuscitation. Isogenic strains of Myc. smegmatis harbouring plasmids containing the Mcc. luteus rpf gene also adopt a similar NC state after growth to stationary phase in modified Hartman's-de Bont medium. However, in contrast to the behaviour noted above, these strains resuscitated spontaneously when transferred to the resuscitation medium, presumably because they are able to resume endogenous synthesis of Mcc. luteus Rpf. Resuscitation was not observed in the control strain harbouring a plasmid lacking Mcc. luteus rpf. In contrast to wild-type, the NC cells of purF and devR mutants obtained under oxygen-limited conditions resuscitate spontaneously, presumably because the heterogeneous population contains some residual viable cells that continue to make Rpf-like proteins.
 ...
PMID:Formation of 'non-culturable' cells of Mycobacterium smegmatis in stationary phase in response to growth under suboptimal conditions and their Rpf-mediated resuscitation. 1518 55

The htx and ptx operons of Pseudomonas stutzeri WM88 allow for the use of the inorganic reduced phosphorus (P) compounds hypophosphite (P valence, +1) and phosphite (P valence, +3) as sole P sources. To support the proposed in vivo role for the htx and ptx operons, namely the use of phosphite and hypophosphite as alternative P sources, we used reporter gene fusions to examine their expression levels with respect to various P conditions. Expression of the htx and ptx operons was induced up to 17- and 22-fold, respectively, in cultures grown under phosphate starvation conditions relative to expression in medium with excess phosphate (Pi). However, the presence of the reduced P substrate hypophosphite, phosphite, or methylphosphonate, in addition to excess Pi, did not result in an increase in the expression of either operon. To provide further support for a role of the htx and ptx operons in Pi acquisition, we identified P. stutzeri phoBR homologs and constructed deletion mutants. Induction of the htx and ptx reporter gene fusions in response to growth on limiting Pi was abolished in DeltaphoB, DeltaphoR, and DeltaphoBR mutants, demonstrating that htx and ptx expression is phoBR dependent. The putative LysR-type regulator encoded by ptxE has no apparent role in the expression of the htx and ptx operons, as no effect was observed on the level of induction of either operon in a DeltaptxE mutant.
 ...
PMID:The htx and ptx operons of Pseudomonas stutzeri WM88 are new members of the pho regulon. 1531 93

Hypophosphatemia is a seldom but potentially fatal complication of the nutritional recovery or refeeding syndrome in patients with protein-calorie malnutrition or starvation. We report here the case of a 35-year-old anorexic patient who presented a severe but uncomplicated hypophosphatemia during enteral refeeding, despite phosphorus supplementation. Serum phosphorus monitoring is recommended in severely malnourished anorexic patients, particularly during the first week of refeeding, be it parenteral or enteral.
 ...
PMID:Severe hypophosphatemia in a patient with anorexia nervosa during enteral refeeding. 1581 81

We report here on a novel transcription factor with a basic helix-loop-helix domain for tolerance to inorganic phosphate (Pi) starvation in rice (Oryza sativa). The gene is designated OsPTF1. The expression of OsPTF1 is Pi starvation induced in roots while constitutively expressed in shoots, as shown by northern-blot analysis. Overexpression of OsPTF1 enhanced tolerance to Pi starvation in transgenic rice. Tillering ability, root and shoot biomass, and phosphorus content of transgenic rice plants were about 30% higher than those of the wild-type plants in Pi-deficient conditions in hydroponic experiments. In soil pot and field experiments, more than 20% increase in tiller number, panicle weight, and phosphorus content was observed in transgenic plants compared to wild-type plants at low-Pi levels. In Pi-deficient conditions, transgenic rice plants showed significantly higher total root length and root surface area, which results in a higher instantaneous Pi uptake rate over their wild-type counterparts. Microarray analysis for transgenic plants overexpressing OsPTF1 has been performed to investigate the downstream regulation of OsPTF1.
 ...
PMID:OsPTF1, a novel transcription factor involved in tolerance to phosphate starvation in rice. 1600 97

Poly-beta-hydroxybutyrate (PHB) accumulation in the unicellular cyanobacterium, Synechocystis sp. PCC 6803, was studied under various cultural and nutritional conditions. Under controlled condition, cells harvested at the stationary phase of growth depicted maximum accumulation of PHB, i.e., 4.5% (w/w of dry cells) as compared to lag (1.8%) or logarithmic (2.9%) phases of cultures. A temperature range of 28-32 degrees C and pH between 7.5 and 8.5 were preferred for PHB accumulation. Cells cultivated under regular light-dark cycles accumulated more PHB (4.5%) than those grown under continuous illumination (2.4%). Nitrogen and phosphorus starvation stimulated PHB accumulation up to the tune of 9.5 and 11% (w/w of dry cells), respectively. Synechocystis cells pre-grown in glucose (0.1%)-supplemented BG-11 medium when subjected to P-deficiency in presence of acetate (0.4%), PHB accumulation was boosted up to 29% (w/w of dry cells), the value almost 6-fold higher with respect to photoautotrophic condition. Fishpond discharges were found as suitable media for PHB accumulation in the test cyanobacterium.
 ...
PMID:Optimization of cultural and nutritional conditions for accumulation of poly-beta-hydroxybutyrate in Synechocystis sp. PCC 6803. 1604 19

Cyanobacteria are equipped with numerous mechanisms that allow them to survive under conditions of nutrient starvation, some of which are unique to these organisms. This review surveys the molecular mechanisms underlying acclimation responses to nitrogen and phosphorus deprivation, with an emphasis on non-diazotrophic freshwater cyanobacteria. As documented for other micro-organisms, nutrient limitation of cyanobacteria elicits both general and specific responses. The general responses occur under any starvation condition and are the result of the stresses imposed by arrested anabolism. In contrast, the specific responses are acclimation processes that occur as a result of limitation for a particular nutrient; they lead to modification of metabolic and physiological routes to compensate for the restriction. First, the general acclimation processes are discussed, with an emphasis on modifications of the photosynthetic apparatus. The molecular mechanisms underlying specific responses to phosphorus and nitrogen-limitation are then outlined, and finally the cross-talk between pathways modulating specific and general responses is described.
 ...
PMID:Acclimation of unicellular cyanobacteria to macronutrient deficiency: emergence of a complex network of cellular responses. 1607 30

Phosphorus, one of the essential elements for plants, is often a limiting nutrient because of its low availability and mobility in soils. Significant changes in plant morphology and biochemical processes are associated with phosphate (Pi) deficiency. However, the molecular bases of these responses to Pi deficiency are not thoroughly elucidated. Therefore, a comprehensive survey of global gene expression in response to Pi deprivation was done by using Arabidopsis thaliana whole genome Affymetrix gene chip (ATH1) to quantify the spatio-temporal variations in transcript abundance of 22,810 genes. The analysis revealed a coordinated induction and suppression of 612 and 254 Pi-responsive genes, respectively. The functional classification of some of these genes indicated their involvement in various metabolic pathways, ion transport, signal transduction, transcriptional regulation, and other processes related to growth and development. This study is a detailed analysis of Pi starvation-induced changes in gene expression of the entire genome of Arabidopsis correlated with biochemical processes. The results not only enhance our knowledge about molecular processes associated with Pi deficiency, but also facilitate the identification of key molecular determinants for improving Pi use by crop species.
 ...
PMID:A genome-wide transcriptional analysis using Arabidopsis thaliana Affymetrix gene chips determined plant responses to phosphate deprivation. 1608 8

Phosphorus is an essential component of macromolecules, like DNA, and central metabolic intermediates, such as sugar phosphates, and bacteria possess enzymes and control mechanisms that provide an optimal supply of phosphorus from the environment. UDP-sugar hydrolases and 5' nucleotidases may play roles in signal transduction, as they do in mammals, in nucleotide salvage, as demonstrated for UshA of Escherichia coli, or in phosphorus metabolism. The Corynebacterium glutamicum gene ushA was found to encode a secreted enzyme which is active as a 5' nucleotidase and a UDP-sugar hydrolase. This enzyme was synthesized and secreted into the medium when C. glutamicum was starved for inorganic phosphate. UshA was required for growth of C. glutamicum on AMP and UDP-glucose as sole sources of phosphorus. Thus, in contrast to UshA from E. coli, C. glutamicum UshA is an important component of the phosphate starvation response of this species and is necessary to access nucleotides and related compounds as sources of phosphorus.
 ...
PMID:Phosphate starvation-inducible gene ushA encodes a 5' nucleotidase required for growth of Corynebacterium glutamicum on media with nucleotides as the phosphorus source. 1608 22

Many microorganisms form symbioses with plants that range, on a continuous scale, from parasitic to mutualistic. Among these, the most widespread mutualistic symbiosis is the arbuscular mycorrhiza, formed between arbuscular mycorrhizal (AM) fungi and vascular flowering plants. These associations occur in terrestrial ecosystems throughout the world and have a global impact on plant phosphorus nutrition. The arbuscular mycorrhiza is an endosymbiosis in which the fungus inhabits the root cortical cells and obtains carbon provided by the plant while it transfers mineral nutrients from the soil to the cortical cells. Development of the symbiosis involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells. The aim of this review is to explore the current understanding of the signals and signaling pathways used by the symbionts for the development of the AM symbiosis. Although the signal molecules used for initial communication are not yet known, recent studies point to their existence. Within the plant, there is evidence of arbuscular mycorrhiza-specific signals and of systemic signaling that influences phosphate-starvation responses and root development. The landmark cloning of three plant signaling proteins required for the development of the symbiosis has provided the first insights into a signaling pathway that is used by AM fungi and by rhizobia for their symbiotic associations with legumes.
 ...
PMID:Signaling in the arbuscular mycorrhizal symbiosis. 1615 62

The population composition of polycultures of Pseudomonas aeruginosa dissociants (R + M and R + S + M) developing on media with various contents and ratios of nitrogen and phosphorus has been studied. Irrespective of its proportion (10 to 90%) in the inoculum, the R variant accounted for 65 to 84% of the whole population of linear-phase and stationary-phase binary cultures of R and M dissociants, which differ in terms of energy metabolism and nutritional requirements. After prolonged cultivation, the population in the binary culture contained only R cells (100%), which are characterized by minimum requirements with respect to the main biogenic elements. These data agree with the predictive data of model studies and can be attributed to regulation of the population composition of bacterial cultures by trophic factors. It was established that the proportion of M cells, which are distinguished by maximum nutrient requirements and enhanced stability, increased during two developmental stages of the Ps. aeruginosa polycultures (R + M and R + S + M): the lag phase and the decay stage. This result cannot be due to the influence of trophic factors and presumably results from changes in the levels of autoregulatory factors (anabiosis autoinducers) involved in stress resistance and plausibly in the adaptive interconversion of dissociants upon transfer to a new medium (during the lag phase) and under starvation conditions (at the onset of the decay phase).
 ...
PMID:[Dynamics of the growth and population composition of the mixed cultures of R, S, and M dissociants of Pseudomonas aeruginosa]. 1621 50


<< Previous 1 2 3 4 5 6 7 8 9 10