Isolation of Drosophila mutants with abnormal proboscis extension reflex

Abstract

Drosophila mutants with defects in their proboscis extension reflex (PER) were isolated for a genetic dissection of the PER system. Five mutant strains were screened from 35,000 mutagenized flies through a twostep screening: a mass test of sugar intake, followed by an individual PER test. Mutants were classified into three complementation groups: aperA (genetical map position, 1-22.11, aperB (1-0.6) and aperC (1-0.4). The aperA mutants showed incomplete penetrance and expressivity. Some flies did not extend their proboscises at all, while others did so only to either the right or the left side; the PERs of the rest were apparently normal. The aperB mutants showed abnormality in the direction of the PER: they extended their proboscises backward, instead of straight forward. The aperB mutation was temperaturesensitive and its phenotype was expressed at a culture temperature above 25°C. The aperC mutation caused a PER defect in aged flies. Within 2 days of eclosion they showed normal PER, but 2 or more days after eclosion most of them had become unable to extend their proboscises. Later, about half of the aperC mutants recovered the PER ability. The anatomical site of action of these mutations seems to be in the neuromuscular or skeletomuscular system. Insect behavior is an integrated expression of neural, muscular, and exoskeletal activities. The role of each element in the behavior mechanism has been analyzed by an experimental replacement of the structure or by its dissection. A study of behavioral mutants provides another way to dissect these mechanisms (Hall and Greenspan, '79; Hall, '82). A systematic genetic dissection of the behavior mechanism is possible in Drosophila m e lanogaster by using induced single-gene mutations.The proboscis extension reflex (PER) is a stereotyped response released by a sugar stimulus applied to the leg tarsus or the mouthpart labellum (Minnich, '21; Dethier, '76). The sensory information from chemosensory hairs is conveyed through the sensory neurons to the central nervous system (CNS) and integrated. The integrated information generates a motoneuron activity and the proboscis extension is evoked by direct muscle actions (van der Starre and Ruigrok, '80). The PER is also regulated by a number of internal signals. Nutritional conditions and gut volume affect the threshold of the PER (Getting and Steinhardt, '72). The isolation of mutants with a single defect at various levels of the PER will allow us to dissect the mechanism of the PER. Several mutants with affected taste reception, the input site of the PER system, have already been isolated (Tanimura, '84). We now set out to isolate X-linked mutants with a defective PER system, and obtained three mutants, aperA aperB, aperC (aper: abnormal proboscis extension reflex). Here we report the genetic and phenotypic characterizations of the isolated PER mutants. MATERIALS AND METHODS Mutagenesis and screeningThe fruit flies Drosophila melanogaster were reared on the usual cornmeal-yeast medium at 25°C under constant illuminatio...

An Inhibitory Sex Pheromone Tastes Bitter for Drosophila Males

“…To assess whether the sensory processing of 7-T affected feeding behavior, we performed the Proboscis Extension Reflex (PER; [24]). When sensilla on the tarsi were unilaterally stimulated with 0.1M sucrose, a positive PER was shown by a majority of male and female flies (Fig.…”

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G-protein gamma subunit 1 is required for sugar reception in Drosophila

“…The PER was examined principally as described (Kimura et al , 1986). Flies aged 3–6 days after eclosion were maintained on fresh medium for 1 day.…”

Drosophila Evaluates and Learns the Nutritional Value of Sugars

“…Next, to determine the correlation between tarsal taste sensitivities and feeding responses to sugars, we performed the proboscis extension reflex test by stimulation of a prothoracic leg [6]. D-glucose and D-arabinose induced reflex responses of similar strengths, whereas D-sorbitol did not ( Figure S2).…”