Genetic and molecular basis of heavy metal tolerance and the heat shock response in the Mediterranean fruit fly : Ceratitis capitata

Sujinda Thanaphum
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The Mediterranean fruit fly (Medfly), Ceratitis capitata, is a major pest of agricultural commodities world wide. Genetic and molecular studies of heavy metal tolerance and the heat shock response in the Medfly can provide a better understanding of how eukaryotes respond to environmental stresses. Potential uses of heavy metal tolerance and a heat shock gene in biological control programs have also been evaluated. Three heavy metal tolerant strains were established. Genetic analyses of test crosses between these strains and a nonselected strain suggested different modes of inheritance underlying the heavy metal tolerance trait. An attempt to generate a Y-autosome translocation involving this trait appeared to not be feasible. PCR products were amplified from the Medfly genome based on conserved domains of a metallothionein gene. Genomic DNA sequences homologous to these PCR products demonstrated coding potential metallothionein proteins, although transcripts homologous to these sequences were not detected in poly(A) selected RNA. This coding potential included a long open reading frame with a potentially cysteine rich region and alignment to mammalian metallothionein proteins. A heat shock like gene (Cerhscl) was cloned from the Medfly using PCR. This PCR used heavy metal induced cDNA as a template and a PCR primer designed from a conserved domain of metallothionein proteins. The Cerhscl gene shows some structural characteristics of a heat inducible gene including the presence of several heat shock elements and the absence of an intron. The Cerhsc1 gene also exhibits a heat shock response resulting in a 10 to 20% increase in the level of transcription. Developmentally, expression of the Cerhsc1 gene is very abundant in the adult stage, less so in the pupal stage and not detectable in the embryo stages. Overall, the Cerhsc1 gene exhibits structural and functional similarities to both heat inducible and non-heat inducible genes from a wide range of organisms.
Thesis (Ph. D.)--University of Hawaii at Manoa, 1995.
Includes bibliographical references (leaves 171-187).
xix, 187 leaves, bound ill. 29 cm
Mediterranean fruit-fly -- Genetics, Mediterranean fruit-fly -- Effect of heavy metals on
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