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Circadian Clock Mutants of Drosophila melanogaster


Konopka, Ronald Jerome (1972) Circadian Clock Mutants of Drosophila melanogaster. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/R04B-3425.


Three mutants of Drosophila melanogaster have been isolated in which the free-running period of the circadian eclosion rhythm and the adult locomotor activity rhythm is affected. One mutant is arrhythmic, another has a short period of 19 hours, and the third has a long period of 28 hours. The mutants retain their phenotypes over the temperature range 18° to 25° C. All three mutants map near the tip of the X chromosome (distal to the centromere). By deficiency mapping, the short-period mutation has been localized to the 3B1-2 region. Complementation tests show that all three mutations affect the same functional gene.

Analysis of activity rhythms of individual mosaic flies indicates that the site of action of the short-period mutation is probably located in the head of the fly. A few activity patterns of split-head and mixed-head mosaics appear to possess both mutant and heterozygous components, suggesting that the fly head may contain two complete clocks capable of maintaining their periodicities independently.

The short-period mutation affects both the duration of the light-insensitive part of the oscillation and the degree to which the clock can be reset during the light-sensitive part of the oscillation.

Both the short-period and long-period mutant eclosion rhythms can be entrained to a period of 24 hours by a 12:12 light-dark cycle having a light intensity at least two orders of magnitude greater than that required to entrain the normal rhythm. The arrhythmic mutant does not entrain under these conditions. In the presence of a temperature cycle, however, the arrhythmic mutant does entrain, but its rhythm damps out when the temperature cycle is removed.

Evidence is presented that Pittendrigh's two-oscillator model for the clock in D. pseudoobscura applies to D. melanogaster as well. The three clock mutations primarily affect the light- sensitive driving oscillator. The arrhythmic mutation appears to have eliminated the driving oscillator while leaving the temperature-sensitive driven oscillator relatively intact.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Biochemistry and Chemistry)
Degree Grantor:California Institute of Technology
Major Option:Biochemistry
Minor Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Benzer, Seymour
Thesis Committee:
  • Benzer, Seymour (chair)
  • Lewis, Edward B.
  • Mitchell, Herschel K.
  • Strumwasser, Felix
  • Vinograd, Jerome
Defense Date:29 February 1972
Funding AgencyGrant Number
Record Number:CaltechTHESIS:04012016-120503899
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9639
Deposited On:01 Apr 2016 20:14
Last Modified:01 Jul 2024 21:10

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