Characterization ofAndante, A NewDrosophilaClock Mutant, and its Interactions with Other Clock Mutants

Abstract

A new clock mutant, named Andante, has been identified on the X chromosome of Drosophila melanogaster. Andante lengthens the period of the circadian eclosion and locomotor activity rhythms by 1.5-2.0 hours. The phase response curves for the eclosion and activity rhythms, indicating light-induced phase shifts, show a similar degree of lengthening. Andante also lengthens the periods of other clock mutants, including Clock, and alleles of the period locus. Analysis of locomotor activity rhythms reveals that Andante is semi-dominant, and Andante rhythms are highly temperature compensated. The sine oculis mutation, which eliminates the outer visual system, has no effect on the period of Andante. Deficiency mapping indicates that Andante is located in the 1OE1-2 to 1OF1 region of the X chromosome, close to the miniature-dusky locus. Whereas Andante flies have a dusky wing phenotype, dusky flies do not have an Andante clock phenotype.

Principles and Problems Revolving Round Rhythm-related Genetic Variants

“…(However, and as is so for any chronovariant at the outset, there was no way to infer that And is a pacemaker mutant per se.) Cycle durations of And adults or of flies emerging from late-developing cultures are only at most 2 hours different from the norm (Konopka et al 1991). This seems to have militated against immediate or even vigorous attempts to take this gene to the molecular level.…”

“…Furthermore, And came with a wing anatomical abnormality whose appearance was like that of the classical dusky (dy) mutants (Konopka et al 1991). Sure enough, the mutational etiology of the And-and dy-like defect mapped to one genetic locus on the X chromosome-to the narrowly defined region where dy mutations (per se) were long known to be located (Konopka et al 1991). Did some dissatisfaction set in thereby, owing to pleiotropy of the And mutant strain?…”

Analysis of conditioned courtship in dusky-Andante rhythm mutants of Drosophila.

“…In the earlier experiments involving rhythm defects and learning, the most dramatically defective mutant was And, notwithstanding the fact that this mutant's circadian clock runs only 1-2 hr more slowly than normal (Konopka et al 1991;Newby et al 1991). A set of novel And-like mutants was induced by mutagenesis, and the isolation of these variants was accompanied by analysis of their pleiotropic effects (Newby et al 1991 ).…”

“…One dy mutant reported by Newby et al (1991), dy n2, was not investigated in the present behavioral experiments owing to its near-normal appearance (see description of "blind-testing" procedure, below). The original dy-related rhythm variant, dy Ana, had been maintained here for many years (having been obtained from R.J. Konopka, a long time before it was reported; Konopka et al 1991 adults. This darkening is not a pigmentation problem but is caused by the fact that individual wing cells of dy flies are smaller than normal (see Newby et al 1991 and references therein).…”

“…Certain dy mutations were reported to produce relatively long-period rhythms (>25 hr), whereas others were ostensibly normal (Konopka et al 1991;Newby et al 1991). Retesting outcrossed versions of these particular mutants yielded circadian-rhythm periodicities (exemplified in Fig.…”