Date of Award:

5-1-1973

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

Eldon J. Gardner

Committee

Eldon J. Gardner

Committee

Spendlove

Committee

Dewey

Abstract

The purpose of this study was to investigate black spottedness, in the eyes of the op-e strain of Drosophila melanogaster. This process has some characteristics of tumor formation and is a hereditarily transmissable trait. It was found that black spot formation resulted from a reduced temperature event occurring just prior to pigment (ommochrome) deposition in the eye. The temperature influenced event required the presence of a genetic factor behaving as a semi-dominant ("sp-e") gene identified with the third chromosome. Black spottedness then developed in a manner characteristic of melanization. Present in the spotted region were grossly abnormal cells that showed evidence of degeneration. The two cell layers in the spotted eye differed. The dioptric layer exhibited a normal pattern of degeneration whereas the retinular layer exhibited extensive granulation. In addition, it was found that a subtle phenotype of spotted-eyed flies had a sensitivity to alcohol. Alcohol dehydrogenase (ADH) extracted from “sp-e" flies after temperature treatment showed two patterns of gene influenced reduction of ADH activity. The “sp-e” reduction of ADH activity followed temperature treatment during a critical period of pupation. The loss of ADH activity began in the last 24 hours of pupation, and was coincident with "melanization” of the dioptric layer. The “sp-e" reduction of ADH activity indicated an alteration of a basic physiological process. The "Adh-” pattern was not dependent on tem perature treatment, and reduction in enzyme activity was not coincident with any developmental event of the Drosophila eye. The “Adh-" reduction of enzyme activity reflected a specific loss of ADH activity. Spottedness, temperature treatment, and the occurrence of different patterns of ADH activity produced a complex phenotype involving three different genes, namely, op-e, “sp-e,” and “Adh- .” In addition, the “Adh-” factor is closely linked with the op-e locus. An examination of said locus revealed properties characteristic of some unstable alleles. The occurrence of hereditarily transmitted and frequently occurring mutant phenotypes may explain the presence of the "Adh-” allele and point to a strain of flies having a mutationally unstable gene. A study of research in the field indicates that reduced-temperature mutants may result from alteration in ribonucleoproteins.

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