Functions and analysis of the seminal fluid proteins of male Drosophila melanogaster fruit flies.

Resistance to organophosphorus insecticides (OP) in Culex pipiens mosquitoes represents a convenient model for investigating the fitness cost of resistance genes and its origin, since both the environmental changes in nature and the adaptive genes are clearly identified. Two loci are involved in this resistance--the super-locus Ester and the locus Ace.1--each displaying several resistance alleles. Population surveys have shown differences in fitness cost between these resistance genes and even between resistance alleles of the same locus. In order to better understand this fitness cost and its variability, the effects of these resistance genes on several fitness-related traits are being studied. Here, through competition experiments between two males for the access to one female, we analysed the effect on paternity success associated with three resistance alleles--Ester4, Ester1 and Ace.1R--relative to susceptible males and relative to one another. The eventual effect of female genotype on male mating success was also studied by using susceptible and resistant females. The strains used in this experiment had the same genetic background. Susceptible males had a mating advantage when competing with any of the resistant males, suggesting a substantial cost of resistance genes to this trait. When competing against susceptible males, the paternity success did not vary among resistant males, whatever the genotype of the female. When competing against other resistant males, no difference in paternity success was apparent, except when the female was Ester1.

Insecticide resistance genes induce a mating competition cost in Culex pipiens mosquitoes.

10 – Sperm Transfer and Use in the Multiple Mating System of Drosophila

The genetic analysis of Drosophila neurobiology has expanded into a considerable field. A host of genetic variants is now available for analyzing the development, structure, physiology, and chemistry of the fly's excitable cells and tissues and how they control the animal's behavior.

Genetics of the nervous system in Drosophila.

The developments between gametogenesis and fertilization: ovulation and female sperm storage in Drosophila melanogaster.

Esterase 6 of Drosophila melanogaster: Kinetics of transfer to females, decay in females and male recovery

The often remarkable similarity in structural gene products among related species has led to the hypothesis that species differences may reside largely in changes at regulatory gene loci. This hypothesis assumes that groups capable of speciating have allelic variation at regulatory loci in their natural populations. We have undertaken an analysis of the mode of regulation of the esterase 6 (Est 6) locus in Drosophila melanogaster to determine the nature and extent of regulatory gene variation in natural populations. Analyses of esterase 6 (EST 6) activity among strains carrying the same thermostability variants reveal that significant, specific-activity differences are present. Reciprocal crosses between lines having high and low EST 6 activity show that loci other than the Est 6 structural gene influence EST 6 activity. Analyses of male hybrids from crosses between D. melanogaster and simulans indicate that the X chromosome of these flies affects the expression of the Est 6 locus, resulting in unequal levels of enzyme activity from the two alleles. The effect is sex and tissue specific. Female hybrids carrying the X chromosomes of both species exhibit equal expression of the two Est 6 alleles. We have determined whether natural populations are polymorphic for X chromosomes which affect EST 6 activity by extracting single X chromosomes from wild-collected males and placing these chromosomes in identical genetic backgrounds. Stocks which are otherwise genetically identical but carry independently derived X chromosomes show significant differences in the activity of EST 6. These data suggest that regulatory loci may be commonly polymorphic in natural populations.

Alayne Senior

Papers

Esterase 6 of Drosophila melanogaster: Kinetics of transfer to females, decay in females and male recovery

Studies of esterase 6 in Drosophila melanogaster: XI. Modification of esterase 6 activity by unlinked genes