Localization and longevity of seminal-fluid esterase 6 in mated female Drosophila melanogaster

Several lines of evidence indicate that natural selection operates between the major EST6-F and EST6-S allozymes of Drosophila melanogaster. In particular, consistent latitudinal clines and seasonal variation in their relative frequencies strongly suggest that they are not selectively equivalent in field populations. Several laboratory studies have found frequency-dependent fitness differences among the Est6-F and Est6-S genotypes. Moreover, the purified EST6-F and EST6-S allozymes differ in biochemical properties and the physiology of the enzyme, as a major component of the seminal fluid, suggests that these differences could affect reproductive aspects of fitness. However, molecular analyses reveal high levels of variation in the EST6 protein both within and between the EST6-F and EST6-S allozymes. Limited thermostability and more sensitive electrophoretic analyses reveal at least 17 variants of the two allozymes and sequence comparisons among 13 isolates of the Est6 gene reveal 16 nucleotide polymorphisms that would lead to amino acid differences. Two closely linked amino acid differences are strongly associated with the major difference between EST6-F and EST6-S; either or both of these are likely to cause the observed biochemical differences between EST6-F and EST6-S and may be the primary targets for the selection between these allozymes. The functional and adaptive significance of the other amino acid polymorphisms is unclear, although the data suggest that the EST6-8 haplotype within EST6-S has both arisen and proliferated relatively recently.Key words: Drosophila melanogaster, esterase 6, nucleotide and amino acid polymorphism, natural selection.

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STUDIES OF ESTERASE 6 IN DROSOPHILA MELANOGASTER. VI. EJACULATE COMPETITIVE ABILITIES OF MALES HAVING NULL OR ACTIVE ALLELES

Genetics ◽

10.1093/genetics/97.1.85 ◽

1981 ◽

Vol 97 (1) ◽

pp. 85-94 ◽

Cited By ~ 1

Author(s):

Donald G Gilbert ◽

Rollin C Richmond

Keyword(s):

Drosophila Melanogaster ◽

Sexual Selection ◽

Competitive Ability ◽

Seminal Fluid ◽

Experimental Conditions ◽

Competition Mechanism ◽

Esterase 6 ◽

Significant Difference ◽

Female Genotype ◽

Male Genotype

ABSTRACT Recent studies of the function of the polymorphic seminal fluid enzyme, esterase 6, of Drosophila melanogaster suggested that it may act in the process of sperm displacement (Gilbert, Richmond and Sheehan, 1981a). This report examines the competitive ability of ejaculates from males homozygous for null or active alleles of esterase 6 under three experimental conditions that model aspects of sexual selection affecting males. The results demonstrate no significant difference in ejaculate competition between esterase 6 null or active male types, but marker males used for paternity identification had poorly competitive ejaculates. The proportion of second-male progeny, P 2, used as an index of competition is primarily influenced by second-male genotype and uninfluenced by female genotype. P2 can change with time from remating and be unaffected by different intensities of competition, which suggests a complex ejaculate competition mechanism.

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Temperature and Sex-Specific Differences in Reproduction Related to Genotypic Variation at the Esterase-6 Locus in Drosophila melanogaster

The American Naturalist ◽

10.1086/285248 ◽

1991 ◽

Vol 138 (3) ◽

pp. 762-767 ◽

Cited By ~ 4

Author(s):

Douglas B. Meikle ◽

Rollin C. Richmond

Keyword(s):

Drosophila Melanogaster ◽

Genotypic Variation ◽

Esterase 6

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Contrasting Histories of Three Gene Regions Associated With In(3L)Payne of Drosophila melanogaster

Genetics ◽

10.1093/genetics/144.4.1565 ◽

1996 ◽

Vol 144 (4) ◽

pp. 1565-1575 ◽

Cited By ~ 3

Author(s):

Esteban Hasson ◽

Walter F Eanes

Keyword(s):

Drosophila Melanogaster ◽

Sequence Variation ◽

Present Report ◽

Genetic Exchange ◽

Nucleotide Variation ◽

Distal Breakpoint ◽

Esterase 6 ◽

The Common ◽

Neutrality Tests ◽

Hsp83 Gene

In the present report, we studied nucleotide variation in three gene regions of Drosophila melanogaster, spanning >5 kb and showing different degrees of association with the cosmopolitan inversion In(3-L)Payne. The analysis of sequence variation in the regions surrounding the breakpoints and the heat shock 83 (Hsp83) gene locus, located close to the distal breakpoint, revealed the absence of shared polymorphisms and the presence of a number of fixed differences between arrangements, indicating absence of genetic exchange. In contrast, for the esterase-6 gene region, located in the center of the inversion, we observed the presence of shared polymorphisms between arrangements suggesting genetic exchange. In the regions close to the breakpoints, the common St arrangement is 10 times more polymorphic than inverted chromosomes. We propose that the lack of recombination between arrangements in these regions coupled with genetic hitchhiking is the best explanation for the low heterozygosity observed in inverted lines. Using the data for the breakpoints, we estimate that this inversion polymorphism is around 0.36 million yr old. Although it is widely accepted that inversions are examples of balanced polymorphisms, none of the current neutrality tests including our Monte Carlo simulations showed significant departure from neutral expectations.

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