Synthesis and cytogenetics of crossover suppressors in the genome of Tribolium castaneum

Giovani Mocelin, Purdue University

Abstract

The red flour beetle, Tribolium castaneum, may serve as an excellent molecular genetic model for the Coleoptera. However, the detection and mapping of biological functions is difficult without a system of crossover suppressors (balancer chromosomes) for large segments of the Tribolium genome. Therefore, I have examined the possibility of constructing balancer chromosomes for four Linkage Groups (LGs) in the Tribolium genome. I have since examined these induced crossover suppressors cytologically and evaluated the use of one of the suppressors for chromosome extraction and genome mapping experiments in beetles. Crossover suppressors were induced by gamma radiation (4 krad). My efforts were most successful for LG3. Two viable unique crossover suppressors had breakpoints associated with the LG3 and a dominant mutation designated Blunt abdominal and metathoraxic projections-27(Bamp-27). One crossover suppressor was associated with the LG4 and a dominant mutation called Displaced sternellun (Ds). Two crossover suppressors were associated with LG2 and a dominant mutation called Eye reduced (Er). For LG5, wild-type chromosomes were exposed to radiation and six crossover suppressors were identified. The distribution of breakpoints among these balancer chromosomes was determined using two- and three-point crosses. Molecular marker, identified as random amplified polymorphic DNA sequence (RAPD) or as restriction fragment length polymorphism (RFLP) was localized to the region balanced by one of the crossover suppressors associated with LG3. Novel mutations, induced by gamma radiation (4 krads) were also recovered within the balanced region. The karyotypes of genetically defined rearrangements were examined cytologically in an attempt to make chromosome/linkage group correlations.

Degree

Ph.D.

Advisors

Stuart, Purdue University.

Subject Area

Entomology|Genetics

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