Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085593 (chills)
 4,268 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Diurnal change in the temperature below or above 12.5 degrees C hastens the degreening of citrus peel and elicits the phytohormone ethylene production in citrus fruit. Ethylene triggers the degradation of chlorophyll and synthesis of carotenoids in citrus peel. To investigate if ethylene is required for the degreening of citrus peel elicited by low temperatures, we studied the chilling-regulated gene expression of ACC synthase, one of the key enzymes catalyzing ethylene biosynthesis. We isolated and characterized a chilling-inducible 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) gene, CS-ACS1, and a chilling-repressible gene, CS-ACS2, from citrus peel. The CS-ACS1 transcript 1.7 kb in length encodes a polypeptide of 483 amino acids (Mr 54,115, pI 6.63), whereas the CS-ACS2 transcript of 1.8 kb encodes a polypeptide of 477 amino acids (Mr 53,291, pI 6.72). Both genes showed a rapid but transient induction (within 2.4 h) of transcripts upon rewarming after the chilling (4 degrees C) treatment. After 24 h of incubation at room temperature, CS-ACS1 mRNA diminished to an undetectable level, whereas the CS-ACS2 mRNA regained its basal level of expression attained prior to the chilling treatment. Chilling-induced ethylene production and ACC accumulation were also observed upon rewarming. Both genes were also induced by the wound stress (excision). The protein synthesis inhibitor cycloheximide super-enhances the accumulation of both ACS transcripts at room temperature. Molecular analysis of the 3.3 kb genomic DNA of CS-ACS1 revealed that this gene consists of three introns and four exons. The intron 3 is exceptionally large ( 1.2 kb) and shares significant homology with mitochondrial DNA, supporting the intron-late theory.
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PMID:Identification of two chilling-regulated 1-aminocyclopropane-1-carboxylate synthase genes from citrus (Citrus sinensis Osbeck) fruit. 1064 19

The aim of the present work was to investigate the effects of osmoconditioning on chilling injury in soybean (Glycine max (L.) Merr.) seeds during imbibition. Soybean seeds germinated readily over a large range of temperatures (10-35 degrees C), the thermal optimum being 25-30 degrees C. Low temperatures reduced the germination rate and no seed germinated at 1 degrees C. Pre-treatment of seeds at 1 degrees C reduced further germination at the optimal temperature (25 degrees C). This deleterious effect of chilling increased with duration of the treatment, and was maximal after 4 days. Osmoconditioning of seeds at 20 degrees C with a polyethylene glycol-8000 solution at -1.5 MPa for at least 24 h followed by drying back the seeds to their initial moisture content reduced their chilling sensitivity and even allowed germination at 1 degrees C. Chilling of control seeds resulted in a sharp decline in in vivo ACC-dependent ethylene production and in an increase in electrolyte leakage in the medium, which indicated deterioration of membrane properties. Osmoconditioned seeds placed at 1 degrees C did not show any reduction in their ability to convert ACC to ethylene nor any strong increase in electrolyte leakage. Imbibition of both control and osmoconditioned seeds at 1 degrees C resulted in a marked increase in ATP level (more than 50% of the total nucleotides) and energy charge; however, the latter cannot be considered as an indicator of chilling since it remained high (0.74-0.88) throughout the cold treatment. Chilling treatment longer than 6 days induced accumulation of malondialdehyde in the embryonic axis, which was more marked in control seeds than in osmoconditioned seeds, suggesting that chilling sensitivity was associated with lipid peroxidation. Imbibition of seeds at 1 degrees C resulted in an increase in superoxide dismutase, catalase and glutathione reductase activity, which was generally higher in osmoconditioned seeds than in control ones. This stimulation of the antioxidant defence systems occurred during the 4 first days of chilling and decreased then in control seeds while it remained high in osmoconditioned ones. Re-warming seeds at 25 degrees C resulted in an increase in all enzyme activity involved in antioxidant defence. However this effect of re-warming decreased in control seeds after 4 days of chilling, whereas it was maintained in osmoconditioned seeds.
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PMID:Osmoconditioning reduces physiological and biochemical damage induced by chilling in soybean seeds. 1129 12