Analysis of Novel Unknown D. melanogaster Mutation trex
Sallianne Roher
University of Houston
Abstract
In this study, a mutation of unknown identity with suspected association with the D. melanogaster gene vestigial was examined in order to determine its characteristics, mode of inheritance, and molecular nature and function. Flies of this mutation, appropriately named trex, display wings smaller in size with a crumpled appearance. Wild type mutant crosses (WTM1 and WTM2) were performed first to determine if the trex phenotype is dominant or recessive by crossing wild-type females with trex males, and then to determine whether it is inherited in an autosomal or sex-linked manner. Mapping crosses were performed using three marker genes (purple, black, and brown) in order to estimate trex’s location within the genome from the resulting recombination frequencies. The association of trex with the given marker genes by genetic linkage was analyzed using chi-square analysis and a p-value test of significance. After extracting DNA from wild type, trex, and reciprocal cross progeny flies, polymerase chain reactions and gel electrophoresis were performed in order to deduce characteristics of the mutation of trex. Further, using BLAST bioinformatic analyses, wild-type and trex gene sequences and protein products were compared to analyze the molecular nature of trex. trex was found to be inherited in an autosomal recessive pattern as evidenced by the results of WTM1 and WTM2, both of which produced an F1 generation that displayed only the wild-type presentation of wing morphology. From the mapping crosses’ recombination frequencies and statistical analysis, it was estimated that trex is located at 2:68 within the genome. Analysis by PCR and gel electrophoresis revealed that the trex mutation is apparent as the addition of genomic material in comparison to the wild-type molecular presentation. These findings were further supported by BLAST analysis, which revealed that the trex mutation was due to the insertion of retrotransposon 412 within the coding sequence. BLAST also revealed trex to be allelic to vestigial, which interacts with a protein produced by scalloped (sd), completing a transcription factor complex regulating wing development. When mutated, as in trex flies, vestigial is unable to perform its normal function and we see phenotypically abnormal wing formation.
