Genetics and Biochemistry of "Red Cells" in Drosophila melanogaster

Author: Grell, Ellsworth Herman

Year: 1958

Degree: Dissertation (Ph.D.)

Advisor: Lewis, Edward B.

Committee Member: Unknown, Unknown

Option: Biology; Biochemistry

DOI: 10.7907/B5AB-S991

Abstract

Studies were made of the "red cells" strain of Drosophila melanogaster. "Red cells" flies are characterized by the presence of reddish pigment in certain fat cells.

A genetic analysis revealed that the fat cells are pigmented only when flies are homozygous for two mutant genes. The two genes are 4.4 crossover units apart on the second chromosome. They were separated, maintained in separate stocks and recombined. When they were recombined the "red cells" phenotype was again produced as it is in the original stock. The two mutant genes have been named red cells (rc) and lysine (lys). With or without rc, the mutant gene, lys, causes flies which are homozygous for it to contain a greater quantity of the amino acid, lysine, than normal flies. In experiments with injection of radioactive lysine, over a period of eight hours normal flies converted thirteen times more lysine into carbon dioxide than did lys flies.

The hypothesis was offered that lys is a mutation of a gene which is important in the degradation of lysine. The mutation causes an impairment in the processes by which lysine is degraded, therefore lysine tends to accumulate in the flies if they ingest more lysine than is required in protein synthesis.

Attempts were made to localize the position of the step at which lys impairs the degradation of lysine.

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