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

Lysine catabolism in plants is initiated by a bifunctional LKR/SDH (lysine-ketoglutarate reductase/saccharopine dehydrogenase) enzyme encoded by a single LKR/SDH gene. Yet, the AtLKR/SDH gene of Arabidopsis also encodes a second gene product, namely a monofunctional SDH. To elucidate the regulation of lysine catabolism in Arabidopsis through these two gene products of the AtLKR/SDH gene, an analysis was carried out on the effects of the hormones, abscisic acid and jasmonate, as well as various metabolic and stress signals, including lysine itself, on their mRNA and protein levels. The response of the two gene products to the various treatments was only partially co-ordinated, but the levels of the monofunctional SDH mRNA and protein were always in excess over their bifunctional LKR/SDH counterparts. These results suggest that lysine catabolism is regulated primarily by the first enzyme LKR, while the excess level of SDH enables efficient flux of lysine catabolism following the LKR step. Analysis of transgenic plants expressing beta-glucoronidase fusion constructs with the AtLKR/SDH and monofunctional AtSDH promoters demonstrated that transcriptional regulation contributes to the modulation of expression of the bifunctional LKR/SDH and monofunctional SDH gene products in response to hormonal and metabolic signals. To test whether the enhanced expression of the LKR/SDH gene under various hormonal and metabolic signals is correlated with enhanced lysine catabolism, wild-type Arabidopsis and a knockout mutant lacking lysine catabolism were exposed to abscisic acid and sugar starvation. Free lysine accumulated to significantly higher levels in this knockout mutant than in the wild-type plants.
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PMID:Regulation of lysine catabolism in Arabidopsis through concertedly regulated synthesis of the two distinct gene products of the composite AtLKR/SDH locus. 1556 7

Malpighian tubules are critical organs for epithelial fluid transport and stress tolerance in insects, and are under neuroendocrine control by multiple neuropeptides secreted by identified neurons. Here, we demonstrate roles for CRF-like diuretic hormone 44 (DH44) and Drosophila melanogaster kinin (Drome-kinin, DK) in desiccation and starvation tolerance. Gene expression and labelled DH44 ligand binding data, as well as highly selective knockdowns and/or neuronal ablations of DH44 in neurons of the pars intercerebralis and DH44 receptor (DH44-R2) in Malpighian tubule principal cells, indicate that suppression of DH44 signalling improves desiccation tolerance of the intact fly. Drome-kinin receptor, encoded by the leucokinin receptor gene, LKR, is expressed in DH44 neurons as well as in stellate cells of the Malpighian tubules. LKR knockdown in DH44-expressing neurons reduces Malpighian tubule-specific LKR, suggesting interactions between DH44 and LK signalling pathways. Finally, although a role for DK in desiccation tolerance was not defined, we demonstrate a novel role for Malpighian tubule cell-specific LKR in starvation tolerance. Starvation increases gene expression of epithelial LKR. Also, Malpighian tubule stellate cell-specific knockdown of LKR significantly reduced starvation tolerance, demonstrating a role for neuropeptide signalling during starvation stress.
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PMID:The corticotropin-releasing factor-like diuretic hormone 44 (DH44) and kinin neuropeptides modulate desiccation and starvation tolerance in Drosophila melanogaster. 2689 69