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

The isolation and complete DNA sequence of a rat genomic clone encoding hsc73, the major hsp70-like protein found in growing cells is described. Unlike the heat-inducible genes characterized so far, the hsc73 gene is interrupted by introns, and there are also numerous intronless hsc73 pseudogenes in the rat genome. We show that the levels of hsc73 mRNA are approximately 5-fold higher in rapidly growing tissue-culture cells than in cells whose growth has been arrested by serum starvation. The abundance of hsc73 mRNA is not significantly increased by heat shock of either fed or starved cells. The hsc73 promoter contains putative binding sites for transcription factor Sp1, two CCAAT boxes and, surprisingly, two matches to the consensus heat-shock regulatory element. When fused to the CAT gene and transfected into COS or HeLa cells, the promoter is constitutively active, showing only a small induction by heat shock. Deletion of some constitutive elements makes it more strongly heat-inducible. The gene thus appears to be subject to more than one form of regulation, mediated by different promoter elements that are intermingled.
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PMID:Cloning and expression of a gene encoding hsc73, the major hsp70-like protein in unstressed rat cells. 359 67

A 4.1 kb genomic clone of the late trypsin gene from the mosquito Aedes aegypti was isolated, mapped and subcloned. A 1.6 kb subclone, corresponding to 1.1 kb of upstream regulatory region and 0.5 kb of coding region, was sequenced. The gene has no introns within the coding region. The 5' end of the mature mRNA was mapped using primer extension analysis. A TATA box consensus sequence (TATAAA) was found at position -31 from the 5' end of the mature mRNA. A cluster of five repeat sequences homologous to the yeast GCN4 DNA binding site was found within 200 nucleotides upstream of the cap site. GCN4 is required for derepression mediated control of general amino acid biosynthesis in response to amino acid starvation in yeast. It activates the transcription of at least twenty different genes coding for enzymes involved in amino acid biosynthesis. The presence of this cluster of consensus sequences suggests that a protein similar to GCN4 might regulate expression of the late trypsin gene in the mosquito. Southern blot analysis of genomic DNA indicates that late trypsin is a single copy gene.
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PMID:Cloning and sequencing of the blood meal-induced late trypsin gene from the mosquito Aedes aegypti and characterization of the upstream regulatory region. 908 37

We have previously isolated a phosphate starvation-response (psr) cDNA clone, psr3.1, from Brassica nigra which encodes a beta-glucosidase. Southern blots of Arabidopsis thaliana genomic DNA probed with the psr3.1 cDNA indicated that this gene exists as a single locus. A genomic library of A. thaliana was screened at high stringency to isolate the corresponding genomic clone. The resultant clone was coined psr3.2 because of its sequence divergence from isolated psr3.1 cDNA clones. Northern blotting with probes derived from the coding region of the genomic clone showed that this gene is expressed at high levels in P(i)-starved roots and the enhancement occurred within two days of growth in medium lacking P(i). The expression of this gene is repressed by heat shock and anaerobic conditions, and it is not significantly induced by high salinity, or by nitrogen or sulfur deprivation. Sequence analysis of the genomic clone revealed the existence of 13 exons interrupted by 12 AT-rich introns and it possessed a high homology with the B. nigra psr3.1 as well as various other beta-glucosidase genes from other species. Sequence similarity and divergence percentages between the deduced amino acid sequences of the psr3 clones and other beta-glycosidases suggests that they should be included along with two other Brassicaceae genes in a distinct subfamily of the BGA glycosidase gene family. The presence of an endoplasmic reticulum retention signal at the carboxy terminus indicates the likely cellular location of PSR3.2. The possible metabolic and regulatory roles of this enzyme during the P(i)-starvation response are discussed.
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PMID:A phosphate-starvation inducible beta-glucosidase gene (psr3.2) isolated from Arabidopsis thaliana is a member of a distinct subfamily of the BGA family. 917 12

Previously we identified Mt4, a phosphate starvation inducible cDNA from Medicago truncatula which is down-regulated in roots in response to phosphate fertilization as well as colonization by arbuscular mycorrhizal (AM) fungi (AM). Here we present further studies of Mt4. Expression was highly sensitive to exogenous applications of phosphate fertilizer; transcripts were abundant in roots fertilized with nutrient solution lacking phosphate, reduced when fertilized with 0.02 or 0.1 mM phosphate and undetectable when fertilized with 1 or 5 mM phosphate. A time course experiment, to study the expression of Mt4 following colonization by AM fungi, revealed that Mt4 transcripts increased in uncolonized roots during the first three weeks of growth and then plateaued, while transcript levels in roots colonized with the AM fungus, Glomas versiforme, increased transiently and then decreased. Although the Mt4 gene is expressed exclusively in roots, transcripts were also detected in M. truncatula cell suspension cultures following phosphate starvation. A genomic clone containing the Mt4 gene and 1133 bp of the 5' flanking sequence was identified from a M. truncatula genomic library. The promoter region contains a conserved cis-element found in the promoters of phosphate starvation inducible genes of yeast and tomato. As Mt4 is the first cDNA reported to show independent regulation by both phosphate and mycorrhizal fungi, the genomic clone may provide a starting point from which to analyze the signal transduction pathways involved in these two processes.
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PMID:Characterization of the Mt4 gene from Medicago truncatula. 971 29

ATP sulfurylase (ATP: sulfate adenylyl transferase, EC 2.7.7.4), the first enzyme of the sulfate assimilation pathway, is present in the chloroplast and cytosol of plants. In Arabidopsis thaliana cDNA cloning revealed the existence of three ATP sulfurylase isoforms (APS1, -2, and -3) all of which appear to be localized in plastids. In the present study the cytosolic isoform was sought by searching the expressed sequence tag (EST) database and by screening A. thaliana genomic libraries. A fourth isoform, APS4, was identified, but it also encodes a plastid-localized isoform. The APS genes all contain four introns. The introns are located at identical positions within the coding sequence of each of the APS genes. A putative TATA box was identified in the promoter of the APS3 and APS4 genes, but no regions of sequence similarity were found among the other promoters. Combined analysis of an APS4 cDNA and genomic clone revealed that the deduced protein is 469 amino acids and is most homologous to the A. thaliana APS1 subclass. The APS4 cDNA was able to functionally complement a yeast ATP sulfurylase (met3) mutant and the recombinant enzyme displayed ATP sulfurylase activity. The APS4 protein exhibits a plastid targeting peptide at its amino terminus that, when fused to green fluorescent protein, was able to target the reporter to chloroplasts. APS4 mRNA was detected at a similar steady-state level in roots and leaves, and its expression was not induced by sulfur starvation or by O-acetylserine treatment. Having identified a fourth plastid-localized ATP sulfurylase, the origin of cytosolic isoform in A. thaliana remains unclear. Based on sequence analysis, it is hypothesized that APS2 may encode the cytosolic ATP sulfurylase.
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PMID:Functional characterization of a gene encoding a fourth ATP sulfurylase isoform from Arabidopsis thaliana. 1080 50

Among the downstream targets of calcium in plants, calcium-dependent protein kinases (CDPKs) form an interesting class of kinases which are activated by calcium binding. They have been implicated in a diverse array of responses to hormonal and environmental stimuli. In order to dissect the role of CDPKs in the moss Funaria hygrometrica, a polymerase chain reaction (PCR)-based approach was adopted to clone the gene. Using degenerate PCR primers against conserved regions of CDPKs, a 900 bp amplicon was obtained from the genomic DNA of Funaria. Southern hybridization under low stringency conditions indicated the presence of several CDPK related sequences in the Funaria genome. This observation is consistent with reports of multigene families of CDPKs in other plants. The 900 bp fragment was subsequently used to isolate a 2.2 kb partial genomic clone of the CDPK gene from Funaria. The genomic clone encodes an open reading frame (ORF) of 518 amino acids. Interestingly, unlike other CDPK genes from plants, the entire 1.5 kb ORF is not interrupted by introns. The deduced amino acid sequence of the Funaria gene shows extensive homology with CDPKs from higher plants, 73% identity with the Fragaria CDPK and 71% identity with CDPK isoform 7 of Arabidopsis. Phylogenetic analysis revealed that the Funaria CDPK is closer to the CDPKs from higher plants like strawberry and Arabidopsis as compared to those from lower plants such as the liverwort Marchantia, the green alga Chlamydomonas or another moss Tortula. Northern analysis shows enhanced expression of the CDPK transcript within 24-48 h of starvation for nitrogen, phosphorus or sulphur. So far the only other kinase which is known to be induced by nutrient starvation in plants is the wpk 4 which is a snf-1 related kinase (SnRKs). To our knowledge this is the first report that implicates a CDPK in the starvation response.
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PMID:Enhanced expression of a calcium-dependent protein kinase from the moss Funaria hygrometrica under nutritional starvation. 1112 May 85

Nitrogen starvation and blue light are the two environmental cues that control sexual differentiation in Chlamydomonas reinhardtii. Insertional mutagenesis was applied to generate mutants that still require nitrogen starvation as the initiating signal for gametogenesis but were no longer dependent on irradiation. In one mutant analysed, sequences adjacent to the site of insertion were cloned and used for the isolation of a genomic clone that, upon transformation, could complement the mutant phenotype. The gene identified (LRG6) encodes two mRNAs that appear to be the products of differential splicing. The two putative gene products derived from these mRNAs differ in their C-terminal ends. Both predicted gene products exhibit multiple hydrophobic domains with alpha-helical secondary structure typical for integral membrane proteins. These proteins may form pores, and may function as transporters of as-yet unknown substrates. Since rendering the LRG6 gene non-functional resulted in light-independence of gamete formation, it is suggested that this transporter may inhibit signal flux from the photoreceptor to target genes - either directly by its activity or indirectly by serving as a scaffold for signalling proteins. Shutting off this transporter may be required for the activation of signal flux in this pathway. This concept is supported by the observed reduction in LRG6 mRNA levels during the first phase of gametic differentiation.
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PMID:Knock-out of a putative transporter results in altered blue-light signalling in Chlamydomonas. 1220 48

The molecular characterization of components involved in nitrate uptake and assimilation in phytoplankton is likely to provide new insights into these processes, their regulation, and their effect on primary production. We report the cloning and initial characterization of the first nitrate transporter genes in a marine organism, from the diatom Cylindrotheca fusiformis Reimann et Lewin. A clone isolated from a silicon-responsive cDNA library was shown by sequence comparison to encode a homolog of high-affinity nitrate transporters. The C. fusiformis nitrate transporter cDNA was named NAT (NitrAte Transporter). The NAT cDNA was used to isolate a genomic clone that contained two additional nitrate transporter genes, NAT1 and NAT2, arranged in tandem. The cDNA and two genomic sequences were highly conserved, and only 18 of 1446 nucleotides in the coding region differed. At least four copies of NAT genes were present in C. fusiformis and as shown by hybridization, multiple copies were present in other diatom species. The transcript abundance of NAT genes in cultures with different nitrogen sources was monitored by RNase protection assays. NAT mRNA levels were high in the presence of nitrate, at nearly the same level during nitrogen starvation, and also high in urea-containing cultures. Lower mRNA levels occurred in nitrite-grown cultures. NAT transcript levels were highly repressed with NH4 Cl or NH4 NO3 as the nitrogen source, although very low amounts were detected. These results suggested that monitoring NAT mRNA levels could serve as a marker for (1) nitrate uptake in nitrate medium, (2) nitrogen starvation, and (3) ammonium use by virtue of absence of expression. NAT mRNA levels were not directly regulated by light or dark, but were apparently related to cellular growth and protein synthesis. Using light/dark synchronized cultures to monitor cell cycle responses, NAT mRNA levels were high in early G1 phase, decreased through the remainder of G1 , then increased during DNA synthesis in S phase and into G2 , and finally decreased after M phase. In silicon-starvation synchronized cultures, levels were high at the G1 /S phase boundary, high throughout S and G2 , and finally decreased after M phase. It was clear that NAT expression, and by inference nitrate uptake, did not occur at continuous levels throughout the cell cycle. The results of the RNase protection experiments suggested that transcriptional regulation is a major contributing factor in the control of diatom nitrate uptake. The cloning of the C. fusiformis nitrate transporter genes provides a new tool for investigating diatom nitrogen uptake and metabolism. In addition, the regulation of NAT expression by nitrogen source is likely to be useful in developing techniques to specifically control the expression of genes fused to NAT regulatory sequences in transgenic diatoms.
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PMID:NITRATE TRANSPORTER GENES FROM THE DIATOM CYLINDROTHECA FUSIFORMIS (BACILLARIOPHYCEAE): mRNA LEVELS CONTROLLED BY NITROGEN SOURCE AND BY THE CELL CYCLE. 2954 59