England P R, Briscoe D A, Frankham R
School of Biological Sciences, Macquarie University, N.S.W., Australia.
Genet Res. 1996 Jun;67(3):285-90. doi: 10.1017/s0016672300033760.
Highly variable DNA polymorphisms called microsatellites are rapidly becoming the marker of choice in population genetic studies. Until now, microsatellites have not been utilized for Drosophila studies. We have identified eight polymorphic microsatellite loci in Drosophila melanogaster and used them to characterize the genetic variation in a wild population from the Tyrrell's winery in Australia. Microsatellites were isolated from a partial genomic DNA library. All microsatellites consist of (AC)n repeats ranging from n = 2 to n = 24. Six loci were assigned to chromosomal location by genetic mapping, with three loci on chromosome II, one locus on chromosome III and two loci on the X chromosome. Up to four microsatellite loci were multiplexed in the same reaction. Microsatellite variation is substantially greater than allozyme variation in the Tyrrell's Drosophila population. 80% of the microsatellite loci examined are polymorphic, compared with 28% of allozymes. The mean number of alleles per polymorphic locus is 5.2 in microsatellites compared with 3.0 in allozymes. The average observed heterozygosity of polymorphic microsatellites is 47% compared with 26% for allozymes. Microsatellite variation in Drosophila melanogaster is similar to that reported for other insects. Higher variability commends microsatellites over allozymes for genetic studies in Drosophila melanogaster.
一种被称为微卫星的高度可变的DNA多态性正迅速成为群体遗传学研究中首选的标记。到目前为止，微卫星尚未用于果蝇研究。我们在黑腹果蝇中鉴定出了8个多态微卫星位点，并利用它们来描述来自澳大利亚泰瑞尔酒庄野生种群的遗传变异。微卫星是从一个部分基因组DNA文库中分离出来的。所有微卫星均由n值从2到24的（AC）n重复序列组成。通过遗传作图将6个位点定位到染色体位置，其中3个位点在第二号染色体上，1个位点在第三号染色体上，2个位点在X染色体上。在同一反应中最多可对4个微卫星位点进行多重分析。在泰瑞尔果蝇种群中，微卫星变异明显大于等位酶变异。所检测的微卫星位点中有80%是多态的，相比之下，等位酶的多态性为28%。每个多态位点的平均等位基因数在微卫星中为5.2个，而在等位酶中为3.0个。多态微卫星的平均观察杂合度为47%，而等位酶为26%。黑腹果蝇中的微卫星变异与其他昆虫报道的情况相似。更高的变异性使得微卫星在黑腹果蝇的遗传研究中比等位酶更具优势。
