van Vugt Joke J F A, van der Hulst Ron G M, Pruijssers Andrea J P, Verbaarschot Patrick, Stouthamer Richard, de Jong Hans
Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH Wageningen, The Netherlands.
Genome. 2009 May;52(5):447-55. doi: 10.1139/g09-024.
The parasitoid wasp Trichogramma kaykai with a haplo-diploid sex determination has a B chromosome called the paternal sex ratio (PSR) chromosome that confers paternal genome loss during early embryogenesis, resulting in male offspring. So far, it is not well known whether the PSR chromosome has unique DNA sequence characteristics. By comparative AFLP fingerprinting of genomic DNA from wasps with and without the PSR chromosome, we isolated DNA from PSR-specific bands. Fourteen of such DNA fragments were analysed to confirm their PSR specificity. Seven were sequenced and two (PT-AFLP 1 and PT-AFLP1 3) were identified as parts of retrotransposon genes based on BLAST searches. Internal primers designed from a third AFLP fragment allowed PCR amplification of a PSR chromosome specific marker, which can be used to screen for the PSR trait in male wasps. Southern analysis revealed a dispersed repetitive nature of this third sequence in the T. kaykai genome, suggesting that it is part of a transposon. A fourth AFLP fragment (PT-AFLP 5) appears to be a large repetitive sequence on the PSR chromosome. This sequence is also found in the genome of both T. kaykai and the closely related species Trichogramma deion, but its distribution on the PSR chromosome strongly resembles that of T. deion rather than that of T. kaykai. Our results provide further insight into the repetitive nature of sequences comprising B chromosomes and their similarities with their host and closely related species.
具有单倍体 - 二倍体性别决定的寄生蜂凯氏赤眼蜂（Trichogramma kaykai）有一条被称为父本性别比（PSR）染色体的B染色体，该染色体在胚胎发育早期导致父本基因组丢失，从而产生雄性后代。到目前为止，尚不清楚PSR染色体是否具有独特的DNA序列特征。通过对具有和不具有PSR染色体的黄蜂基因组DNA进行比较AFLP指纹分析，我们从PSR特异性条带中分离出DNA。对14个这样的DNA片段进行了分析，以确认它们的PSR特异性。对其中7个进行了测序，基于BLAST搜索，其中两个（PT - AFLP 1和PT - AFLP1 3）被鉴定为反转录转座子基因的一部分。从第三个AFLP片段设计的内部引物允许PCR扩增PSR染色体特异性标记，可用于筛选雄性黄蜂中的PSR性状。Southern分析揭示了该第三个序列在凯氏赤眼蜂基因组中的分散重复性质，表明它是转座子的一部分。第四个AFLP片段（PT - AFLP 5）似乎是PSR染色体上的一个大的重复序列。该序列也存在于凯氏赤眼蜂和密切相关物种德氏赤眼蜂（Trichogramma deion）的基因组中，但其在PSR染色体上的分布与德氏赤眼蜂的非常相似，而不是与凯氏赤眼蜂的相似。我们的结果进一步揭示了构成B染色体的序列的重复性质及其与宿主和密切相关物种的相似性。
