THE FORMATION OF DUMPY VORTICES IN MOSAICS OF DROSOPHILA MELANOGASTER
Certain alleles of the gene dp produce vortices, which are changes in the configuration of the dorsal surface of the thorax and in the distribution of thoracic chaetae and hairs. The dp alleles appear to affect the chaeta pattern through tissue movement, since they do not change the total number of bristle organs. Cellular changes which occur are bristle organs with doubled chaetae, and small bald'' areas devoid of chaetae and cell hairs. The vortices are associated with insertions of certain of the indirect flight muscles through deep invaginations of the hypodermis and cuticle. Vortex formation begins prior to normal attachment of the flight muscles: the formation of vortices is indirectly responsible for the development of doubled chaetae. X-ray induced somatic crossing over produced mosaic patches which were homozygous for dp and homozygous or hemizygous for yellow on a heterozygous wild-type background. Thirteen mosaics, including eight involving recessive lethal alleles, were recovered from an estimated 7,000 treated individuals. In the mosaic specimens, the dumpy recessives are nonautonomous: homozygous recessive patches bring about the vortex pattern in the adjacent heterozygous or homozygous dominant tissue, and, in three cases, in the heterozygous tissue of the opposite side of the thorax. The doubling of chaetae in the vortices is an indirect effect, since it sometimes occurs in the background tissue. The wild-type allele of dp, in response to specific developmental environments, appears to regulate (either directly or by intracellular inhibition) the production of a supracellular factor, which in turn affects tissue movement. The recessive alleles apparently fail to respond to these developmental environments, leading to a failure to regulate the production of the supracellular factor and thus to abnormal tissue movement. It is concluded that dp is not a prepattern gene with respect to the distribution of thoracic bristle organs, since it does not have any effect on the determination of bristle organ anlagen. The differentiation of doubled chaeate, however, is due to a physical change in the cellular environment, indirectly brought about by dp; in this minor respect dp can be considered a prepattern gene. (auth)
- Research Organization:
- Univ. of California, Berkeley
- NSA Number:
- NSA-18-013491
- OSTI ID:
- 4089957
- Journal Information:
- Genetics (U.S.), Vol. Vol: 49; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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