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

Our aim was to generate and prove the concept of "smart" plants to monitor plant phosphorus (P) status in Arabidopsis. Smart plants can be genetically engineered by transformation with a construct containing the promoter of a gene up-regulated specifically by P starvation in an accessible tissue upstream of a marker gene such as beta-glucuronidase (GUS). First, using microarrays, we identified genes whose expression changed more than 2.5-fold in shoots of plants growing hydroponically when P, but not N or K, was withheld from the nutrient solution. The transient changes in gene expression occurring immediately (4 h) after P withdrawal were highly variable, and many nonspecific, shock-induced genes were up-regulated during this period. However, two common putative cis-regulatory elements (a PHO-like element and a TATA box-like element) were present significantly more often in the promoters of genes whose expression increased 4 h after the withdrawal of P compared with their general occurrence in the promoters of all genes represented on the microarray. Surprisingly, the expression of only four genes differed between shoots of P-starved and -replete plants 28 h after P was withdrawn. This lull in differential gene expression preceded the differential expression of a new group of 61 genes 100 h after withdrawing P. A literature survey indicated that the expression of many of these "late" genes responded specifically to P starvation. Shoots had reduced P after 100 h, but growth was unaffected. The expression of SQD1, a gene involved in the synthesis of sulfolipids, responded specifically to P starvation and was increased 100 h after withdrawing P. Leaves of Arabidopsis bearing a SQD1::GUS construct showed increased GUS activity after P withdrawal, which was detectable before P starvation limited growth. Hence, smart plants can monitor plant P status. Transferring this technology to crops would allow precision management of P fertilization, thereby maintaining yields while reducing costs, conserving natural resources, and preventing pollution.
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PMID:Changes in gene expression in Arabidopsis shoots during phosphate starvation and the potential for developing smart plants. 1280 89

The phosphate (P(i)) starvation stimulon of Corynebacterium glutamicum was characterized by global gene expression analysis by using DNA microarrays. Hierarchical cluster analysis of the genes showing altered expression 10 to 180 min after a shift from P(i)-sufficient to P(i)-limiting conditions led to identification of five groups comprising 92 genes. Four of these groups included genes which are not directly involved in P metabolism and changed expression presumably due to the reduced growth rate observed after the shift or to the exchange of medium. One group, however, comprised 25 genes, most of which are obviously related to phosphorus (P) uptake and metabolism and exhibited 4- to >30-fold-greater expression after the shift to P(i) limitation. Among these genes, the RNA levels of the pstSCAB (ABC-type P(i) uptake system), glpQ (glycerophosphoryldiester phosphodiesterase), ugpAEBC (ABC-type sn-glycerol 3-phosphate uptake system), phoH (unknown function), nucH (extracellular nuclease), and Cgl0328 (5'-nucleotidase or related esterase) genes were increased, and pstSCAB exhibited a faster response than the other genes. Transcriptional fusion analyses revealed that elevated expression of pstSCAB and ugpAEBC was primarily due to transcriptional regulation. Several genes also involved in P uptake and metabolism were not affected by P(i) starvation; these included the genes encoding a PitA-like P(i) uptake system and a putative Na(+)-dependent P(i) transporter and the genes involved in the metabolism of pyrophosphate and polyphosphate. In summary, a global, time-resolved picture of the response of C. glutamicum to P(i) starvation was obtained.
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PMID:The phosphate starvation stimulon of Corynebacterium glutamicum determined by DNA microarray analyses. 1286 61

Cultures of Escherichia coli will not grow in media containing very high specific activities of radiophosphorus P(32), the inhibition of growth being due to the decay of assimilated P(32) atoms. Experiments with a differentially labeled thymineless strain of E. coli show that the P(32) disintegrations which occur in the bacterial deoxyribonucleic acid, i.e. in the nucleus, are mainly responsible for the inactivation of the cell. The kinetics with which radioactive bacterial populations are inactivated indicate that the function of several nuclei per bacterial cell must be eliminated by P(32) decay before the ability to generate a colony is lost. The efficiency with which each P(32) disintegration inactivates the nucleus in which it has occurred is calculated to be 0.02 (at -196 degrees ), i.e., similar in magnitude to the killing efficiency of P(32) decay in bacteriophages. P(32) decay and thymine starvation cooperate in bringing about the death of individuals of the thymineless strain, from which observation it is inferred that "thymineless death" is likewise a nuclear inactivation. The descendants of a non-radioactive bacterial culture grown for several generations in the presence of P(32) and the descendants of a radioactive culture grown in the absence of P(32) are inactivated by P(32) decay in a manner which indicates that the phosphorus atoms of bacterial nuclei are dispersed among the progeny nuclei in their line of descendance.
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PMID:Inactivation of bacteria by decay of incorporated radioactive phosphorus. 1335 38

Harold, F. M. (National Jewish Hospital, Denver, Colo.) and Susan Sylvan. Accumulation of inorganic polyphosphate in Aerobacter aerogenes. II. Environmental control and the role of sulfur compounds. J. Bacteriol. 86:222-231. 1963.-The accumulation of inorganic polyphosphate in Aerobacter aerogenes was shown to be a function of the growth medium. In low-phosphate medium, polyphosphate accumulated whenever nucleic acid synthesis ceased due to a nutritional deficiency, regardless of its nature. In high-phosphate medium polyphosphate accumulation was induced only by sulfur starvation. Polyphosphate accumulation could thus be induced or suppressed at will by manipulation of the sulfur and phosphorus content of the medium. The specific requirement for sulfur starvation was traced to the presence of an intracellular inhibitor of polyphosphate accumulation. This was depleted during sulfur starvation and replenished when sulfate was restored. The inhibitor was identified as oxidized glutathione or a closely related compound. Suppression of polyphosphate accumulation required the simultaneous presence of a high exogenous phosphate concentration and a high intracellular glutathione level. Suppression of polyphosphate accumulation resulted in a constant polyphosphate level, due to a steady state of polyphosphate synthesis and degradation. The former continued at half the original rate while the latter was sharply accelerated. The synthetic and degradative phases of polyphosphate metabolism could be completely dissociated by inhibitors of energy generation. It is proposed that the primary effect of glutathione plus phosphate is the stimulation of polyphosphate degradation. Polyphosphate synthesis appears to be a general consequence of the inhibition of nucleic acid synthesis, but net accumulation may be obscured by concurrent degradation.
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PMID:ACCUMULATION OF INORGANIC POLYPHOSPHATE IN AEROBACTER AEROGENES. II. ENVIRONMENTAL CONTROL AND THE ROLE OF SULFUR COMPOUNDS. 1405 45

Mallette, M. F. (Pennsylvania State University, University Park), Cynthia I. Cowan, and J. J. R. Campbell. Growth and survival of Escherichia coli in medium limited in phosphate. J. Bacteriol. 87:779-785. 1964.-Washed suspensions of Escherichia coli B increased in turbidity and plate count when incubated at 36.5 to 38 C without added phosphate. The population increased more quickly than did the turbidity. On continued incubation, cell viability decreased rapidly in the presence of all necessary nutrients except phosphate. The decline in viability was logarithmic for 90% of the death curve, suggesting loss of a single critical process. Various combinations of phosphate-starved cells and log-phase cells with fresh, phosphate-deficient and phosphate-containing media, and medium depleted of any contaminating phosphate suggested that the simple, phosphate-deficient medium was, in fact, devoid of available phosphorus. This deduction was confirmed by the linearity and extrapolation through the origin of a plot of turbidity against inoculum size. Cell suspensions increased in a linear manner, with the phosphate concentration at low levels. Therefore, a threshold requirement of phosphate for growth of E. coli did not exist, at least, above 1 x 10(-9) moles of phosphate per ml. Thus, there is no maintenance level for phosphorus in the organism analogous to the energy of maintenance. When cells had been previously incubated without exogenous phosphate, their subsequent response to added phosphate was limited. Moderate additions of phosphate did not raise the turbidity much above a plateau value reached at lower phosphate concentrations. Under such conditions, the cells were still viable as measured by plate counting. Yet, when returned to a relatively complete but simple medium after starvation, they could not divide normally. Growth of E. coli in a medium deficient only in phosphate rendered the cells susceptible to death on continued incubation. Apparently, material lost during starvation was necessary for multiplication. It was replaced by the plating medium and colonies formed.
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PMID:GROWTH AND SURVIVAL OF ESCHERICHIA COLI IN MEDIUM LIMITED IN PHOSPHATE. 1413 13

Phytate, the main form of phosphorus storage in plant seeds, is well known to be an anti-nutrient and a major source of phosphorus pollution in animal manure. To improve phosphorus bio-availability, we introduced a recently characterized phytase from Bacillus subtilis into the cytoplasm of tobacco cells. Although the introduction of acid fungal phytase from Aspergillus niger in previous studies did not result in any phenotypic changes in tobacco, here we show that a tobacco line transformed with a neutral phytase exhibited phenotypic changes in flowering, seed development, and response to phosphate deficiency. The transgenic line showed an increase in flower and fruit numbers, small seed syndrome, lower seed IP6/IP5 ratio, and enhanced growth under phosphate-starvation conditions compared with the wildtype. The results suggest that the over-expression of Bacillus phytase in the cytoplasm of tobacco cells shifts the equilibrium of the inositol phosphate biosynthesis pathway, thereby making more phosphate available for primary metabolism. The approach presented here can be applied as a strategy for boosting productivity in agriculture and horticulture.
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PMID:The introduction of a phytase gene from Bacillus subtilis improved the growth performance of transgenic tobacco. 1455 35

Purple acid phosphatases (PAPs) are commonly found in plants, but the physiological functions of different classes of PAPs are not thoroughly understood. In the present study, we identified a novel gene, GmPAP3, from salt-stressed soybean using suppression subtractive hybridization (SSH) techniques. Protein sequence alignment studies and phylogenetic analysis strongly suggested that GmPAP3 belongs to the group of plant PAPs and PAP-like proteins that are distinct from those of fungi and animals. In addition, the invariable consensus metal binding residues of PAPs were all conserved in GmPAP3. Surprisingly, analysis of protein sorting signals showed that a putative mitochondrion targeting transit peptide is present on GmPAP3. Northern blot analysis revealed that NaCl stress causes a general induction of GmPAP3 expression in both roots and leaves of various cultivated (Glycine max) and wild (Glycine soja) soybean varieties. Further test using two genetically unrelated cultivated soybean varieties showed that the expression pattern of GmPAP3 is distinct from other PAP genes in soybeans. NaCl stress and oxidative stress but not phosphorus (P) starvation induces the expression of GmPAP3. These results suggest that the physiological role of GmPAP3 might be related to the adaptation of soybean to NaCl stress, possibly through its involvement in reactive oxygen species (ROS) forming and/or scavenging or stress-responding signal transduction pathways.
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PMID:GmPAP3, a novel purple acid phosphatase-like gene in soybean induced by NaCl stress but not phosphorus deficiency. 1458 3

Plants have evolved complex strategies to maintain phosphate (Pi) homeostasis and to maximize Pi acquisition when the macronutrient is limiting. Adjustment of root system architecture via changes in meristem initiation and activity is integral to the acclimation process. However, the mechanisms that monitor external Pi status and interpret the nutritional signal remain to be elucidated. Here, we present evidence that the Pi deficiency response, pdr2, mutation disrupts local Pi sensing. The sensitivity and amplitude of metabolic Pi-starvation responses, such as Pi-responsive gene expression or accumulation of anthocyanins and starch, are enhanced in pdr2 seedlings. However, the most conspicuous alteration of pdr2 is a conditional short-root phenotype that is specific for Pi deficiency and caused by selective inhibition of root cell division followed by cell death below a threshold concentration of about 0.1 mm external Pi. Measurements of general Pi uptake and of total phosphorus (P) in root tips exclude a defect in high-affinity Pi acquisition. Rescue of root meristem activity in Pi-starved pdr2 by phosphite (Phi), a non-metabolizable Pi analog, and divided-root experiments suggest that pdr2 disrupts sensing of low external Pi availability. Thus, PDR2 is proposed to function at a Pi-sensitive checkpoint in root development, which monitors environmental Pi status, maintains and fine-tunes meristematic activity, and finally adjusts root system architecture to maximize Pi acquisition.
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PMID:Arabidopsis pdr2 reveals a phosphate-sensitive checkpoint in root development. 1499 15

Phosphorus is one of the major plant nutrients that is least available in the soil. Consequently, plants have developed numerous morphological, physiological, biochemical, and molecular adaptations to acquire phosphate (Pi). Enhanced ability to acquire Pi and altered gene expression are the hallmarks of plant adaptation to Pi deficiency. The intricate mechanisms involved in maintaining Pi homeostasis reflect the complexity of Pi acquisition and translocation in plants. Recent discoveries of multiple Pi transporters have opened up opportunities to study the molecular basis of Pi acquisition by plants. An increasing number of genes are now known to be activated under Pi starvation. Some of these genes may be involved in Pi acquisition, transfer, and signal transduction during Pi stress. This review provides an overview of plant adaptations leading to enhanced Pi acquisition, with special emphasis on recent developments in the molecular biology of Pi acquisition.
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PMID:PHOSPHATE ACQUISITION. 1501 23

Agricultural and animal husbandry practices combined with soil composition have caused phosphate overloading of farmlands in different parts of the U.S. and Europe. Movement of soluble phosphates (Pi) from phosphorus enriched soils results in degradation of natural aquatic systems, triggering serious environmental problems. Remediation of such sites using plants that tolerate and accumulate high concentrations of Pi in their aerial parts may be an attractive remediation technology. In the present study, Pi transport and accumulation potential of Marshall and Gulf ryegrass (Lolium multiflorum cultivars) were determined using a solution culture of seedlings. Ryegrass seedlings accumulated phosphorus (P) in excess of 2% of dry weight in their aerial parts when supplied with 5 g/L KH2PO4 in medium. Phosphorus accumulation was positively correlated with the concentration of phosphate (0-5 g/L KH2PO4) in medium. Plants grew well on medium containing 5 g/L KH2PO4, but concentrations above 5 g/L caused symptoms of toxicity. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed high P accumulation in different cell types of grass roots and shoots. Phosphate starvation and replenishment experiments point to the unique ability of these grasses to concentrate phosphate in the above-ground parts. It is hypothesized that the unique ability of these ryegrass cultivars may be due to the presence of efficient phosphate transport and sequestration mechanisms.
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PMID:Enhanced accumulation of phosphate by Lolium multiflorum cultivars grown in phosphate-enriched medium. 1511 52


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