title: Transcripts from the Drosophila heat-shock gene hsr-omega influence rates of protein synthesis but hardly affect resistance to heat knockdown.
abstract: While hundreds of genes have recently been implicated in an organism's response to thermal stress, our insight into the cellular and physiological mechanisms affected by these genes has advanced to a lesser extent. We focus on an enigmatic Drosophila heat stress RNA gene, hsr-omega, which encodes two RNA transcripts that are constitutively expressed in almost all developing and adult tissues, omega-n in the nucleus and omega-c in the cytoplasm; both being readily induced to high levels by mild heat stress. We derived three hsr-omega mutant lines via imprecise P-element excision and characterised them for changes in expression, in both the presence and absence of heat stress. Viability estimates indicate that a low level of omega-n is required for normal development. Consistent with the model of omega-n as a negative regulator of intron-processed mRNA levels the mutants displayed a 1.5-fold increase in rates of protein synthesis measured in ovarian tissue in the absence of heat stress, a result suggesting that an important function of hsr-omega is the modulation of general protein synthesis. The mutants had little effect on two measures commonly used to assess heat tolerance, heat-knockdown time and heat hardening ability, suggesting that more subtle heat-related fitness components need to be examined for effects of these mutations.
authors.affiliation: Centre for Environmental Stress and Adaptation Research, School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia. travis.johnson@monash.edu
authors.forename: Travis K
authors.initials: TK
authors.lastname: Johnson
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Cockerell
authors.forename: Stephen W
authors.initials: SW
authors.lastname: McKechnie
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000483:Alleles; D000818:Animals; D001483:Base Sequence; D004251:DNA Transposable Elements / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D017344:Genes, Insect / Q000235:genetics*; D056426:Genetic Loci / Q000235:genetics; D018869:Heat-Shock Response / Q000235:genetics*; D006358:Hot Temperature; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis
chemical_list: D004251:DNA Transposable Elements; D012333:RNA, Messenger