Genomic analysis of Drosophila ananassae and its sibling species by means of parthenogenetic hybrid

由孤雌生殖的果蝇品系ananassae（单性无父品系雌性）和D.pallidosa（两性桥品系雄性）的杂交产生杂种。由于前者在XL（X染色体的左臂;下文中染色体臂的缩写类似（L，左臂; R，右臂））上有一个可见的标记黄色，杂交通过雌性的黄色^+表型来证实。F_1雌株孤雌生殖后代，F_2雌株建立266个株系。所述品系具有各种基因型，所述基因型具有种间嵌合基因组，所述种间嵌合基因组是纯合的（即，等基因的）。我们研究了每个嵌合体基因组系的基因组结构（每个染色体区域的物种起源）。黄绿杜父虫的In（3R）A和黄绿杜父虫的In（XL）A、In（2L）CD+B和In（3R）B染色体倒位。苍白球作为细胞学标记。利用6个已确定细胞学位置的PCR-RFLP标记（w（XR）、Om（2D）（2 mid）、eyg（2 R）、cn（3L）、Amyrel（3 mid）和RfaBp（4））和2个与上述倒位完全连锁的RAPD标记（OPA 15 -950（2L）和OPA 15 -1200（3R））。所有品系的基因组结构均已确定。统计检验表明2L和3R之间存在准连锁。这可能是由于（1）某些基因型的低适合度（育性或活力）或（2）减数分裂中同一物种起源的染色体同时分布。我们将使用这里建立的种间嵌合基因组系来定位决定种特异性特征（包括性行为）的基因。

Hybrids were made from the cross of parthenogenetic strains of Drosophila ananassae (a unisexual impaternate strain females) and D.pallidosa (a bisexual bridge strain males). As the former has a visible marker yellow on XL (the left arm of the X chromosome ; hereafter chromosome arms are abbreviated similarly (L, the left arm ; R, the right arm)), hybridism is confirmed by the yellow^+ phenotype of the females. The F_1 females produce offspring parthenogenetically and 266 lines were established from individual F_2 females. The lines have various genotypes with interspecific mosaic genomes which are made homozygous (i.e., iso-genic). We investigated the genomic structure (the species origin of every chromosome region) of each mosaic genome lines. Chromosome inversions In(3R)A of D.ananassae and In(XL)A, In(2L)CD+B and In (3R)B of D. pallidosa were utilized for cytological markers. 6 PCR-RFLP markers whose cytological locations have been determined (w (XR), Om (2D)(2mid), eyg (2R), cn (3L), Amyrel (3mid) and RfaBp (4)) plus 2 RAPD markers completely linked to the above-mentioned inversions (OPA15-950 (2L) and OPA15-1200 (3R)) were also utilized. The genomic structure of all the lines has been determined. The statistical test indicated quasi-linkage between 2L and 3R. This might be caused by either (1)low fitness (fertility or viability) of some genotypes or (2)simultaneous distribution of the chromosomes of the same species origin in meiosis. We are going to use the interspecific mosaic genome lines established here for the mapping of genes determining species-specific characters (including sexual behavior).