tailieunhanh - Báo cáo khoa học: ArHsp22, a developmentally regulated small heat shock protein produced in diapause-destined Artemia embryos, is stress inducible in adults

Diapause embryos of the crustaceanArtemia franciscanaexhibit extreme stress tolerance, a property thought to involve molecular chaperones known as small heat shock proteins. To further explore this idea, the struc-ture, function and synthesis of ArHsp22, an Artemiasmall heat shock protein, were characterized. | ễFEBS Journal ArHsp22 a developmentally regulated small heat shock protein produced in diapause-destined Artemia embryos is stress inducible in adults Zhijun Qiu and Thomas H. MacRae Department of Biology Dalhousie University Halifax Canada Keywords Artemia franciscana diapause molecular chaperone small heat shock protein stress tolerance Correspondence T. H. MacRae Department of Biology Dalhousie University Halifax Nova Scotia B3H 4J1 Canada Fax 1 902 494 3736 Tel 1 902 494 6525 E-mail tmacrae@ Received 1 April2008 accepted 12 May 2008 doi Diapause embryos of the crustacean Artemia franciscana exhibit extreme stress tolerance a property thought to involve molecular chaperones known as small heat shock proteins. To further explore this idea the structure function and synthesis of ArHsp22 an Artemia small heat shock protein were characterized. ArHsp22 contains amino-terminal WXDPF motifs an a-crystallin domain with a highly conserved arginine and a car-boxy-terminal I VXI V motif all typical of small heat shock proteins. ArHsp22 formed large oligomers and exhibited molecular chaperone activity in vitro protecting citrate synthase and insulin from denaturation. Quantitative PCR and immunoprobing of western blots revealed that ArHsp22 synthesis is restricted to diapause-destined Artemia embryos and that the protein is degraded during post-diapause development. ArHsp22 was observed in cyst nuclei a location shared by p26 but not ArHsp21 which are two other diapause-specific Artemia small heat shock proteins. ArHsp22 production was enhanced by thermal stress but only in adults thus representing the first crustacean small heat shock protein whose synthesis is known to be both developmentally regulated and stress inducible. The results demonstrate that expression of the gene for ArHsp22 is modulated by multiple cues that vary with life history stage. Such findings are of importance in understanding diapause maintenance in Artemia .

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