The tumorous-head-1 locus affects bristle number of the Drosophila melanogaster cuticle.
The tuh-1 maternal effect locus contains two naturally occurring isoalleles, tuh-1h and tuh-1g. Until recently there has been no possibility to distinguish between the tuh-lh and the tuh-1g maternal effects other than evaluating their effect on the Bithorax-Complex (BXC) Abdominal B (Abd-B) mutant tuh-3. However, in this report we identify a bristle phenotype associated with the tuh-1 locus that has very interesting evolutionary implications. Females homozygous for tuh-1h always produce adult offspring with more bristles than females homozygous or heterozygous for tuh-1g. The effect is global. Increased bristle number occurs in the head, the thorax, and the anterior and posterior abdomen. Females totally deficient for the tuh-1 gene produce offspring with high bristle number. Thus, the bristle phenotype results from the absence of the maternally contributed tuh-1g factor. Genetic evidence shows that the bristle phenotype is caused by the tuh-1 locus and that tuh-1h is completely recessive to tuh-1g. The tuh-1 locus is located at the euchromatin-beta-heterochromatin junction near the centromere of the X chromosome and deficiency analysis places the locus between the lethal genes extra organs (eo) and lethal B20 (lB20). The variance in bristle number attributable to the tuh-1 locus in nature is approximately 10.1%, an indication that the bristle phenotype is most likely a neutral, pleiotrophic side effect of tuh-1.
Packert
G
G
Department of Biology, University of Central Florida, Orlando 32816-0990, USA.
Kuhn
D T
DT
D000005:Abdomen / Q000254:growth & development; D000818:Animals; D003433:Crosses, Genetic; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D017344:Genes, Insect / Q000235:genetics*; D006257:Head / Q000254:growth & development; D006579:Heterozygote; D006720:Homozygote; D010641:Phenotype; D013696:Temperature; D013909:Thorax / Q000254:growth & development; D014960:X Chromosome