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dc.contributor.authorQiu, Zhijun.en_US
dc.date.accessioned2014-10-21T12:34:57Z
dc.date.available2006
dc.date.issued2006en_US
dc.identifier.otherAAINR16688en_US
dc.identifier.urihttp://hdl.handle.net/10222/54778
dc.descriptionDuring oviparous development, Artemia embryos encyst and enter diapause, a condition characterized by low metabolic activity and high tolerance to environmental stress. Entry into diapause is thought to involve differential gene expression leading to synthesis of regulatory and structural proteins that modulate organismal behavior, and during diapause stress proteins are may protect encysted embryos. Subtractive hybridization was utilized to recover several up-regulated genes, including those that encode the small heat shock proteins (sHSPs) ArHsp21 and ArHsp22, and p8, a cotranscription factor. Full length cDNAs of ArHsp21 and ArHsp22 encode 181 and 190 amino acid residues, respectively, with a conserved alpha-crystallin domain. ArHsp21 and ArHsp22 form oligomers and exhibit chaperone activity, functional characteristics of most sHSPs. These sHSPs are detected during oviparous but not ovoviviparous development and upon exposure of adult Artemia to thermal stress, synthesis of ArHsp22 was observed. In contrast, instar II larvae synthesized neither ArHsp21 nor ArHsp22 in response to heat shock. ArHsp21 and ArHsp22 have the potential to protect Artemia embryos during development, whereas only ArHsp22 is stress inducible. Artemia p8 contains 66 amino acid residues and its sequence is similar to p8 from other organisms. Probing of Southern blots indicated a single p8 gene in Artemia. p8 transcripts are present in low amounts in oocytes prior to fertilization and increase rapidly, peaking at one day post-fertilization during oviparous but not ovoviviparous development. p8 protein is present at two days post-fertilization and is found in encysted embryos released from females, where it was detected in nuclei by immunofluorescent staining. The properties of p8 are consistent with a role in regulation of Artemia entry into encystment. As a representative of Artemia sHSPs, p26 gene structure was analyzed, revealing four exons and three introns, with one intron in the 5'-untranslated region. Cis-acting elements such as putative estrogen and Ap-1 binding sites, and heat shock elements, were found in the first intron and the 5'-flanking upstream region of the p26 gene, and they may contribute to developmental regulation of this gene.en_US
dc.descriptionThesis (Ph.D.)--Dalhousie University (Canada), 2006.en_US
dc.languageengen_US
dc.publisherDalhousie Universityen_US
dc.publisheren_US
dc.subjectBiology, Molecular.en_US
dc.subjectBiology, Zoology.en_US
dc.titleMolecular analysis of encystment and diapause in Artemia: Gene expression and stress response.en_US
dc.typetexten_US
dc.contributor.degreePh.D.en_US
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