Vítková Magda, Fuková Iva, Kubícková Svatava, Marec Frantisek
Biology Centre ASCR, Institute of Entomology, Branisovská 31, CZ-370 05, Ceské Budejovice, Czech Republic.
Chromosome Res. 2007;15(7):917-30. doi: 10.1007/s10577-007-1173-7. Epub 2007 Nov 7.
Most Lepidoptera have a WZ/ZZ sex chromosome system. We compared structure of W chromosomes in four representatives of the family Pyralidae--Ephestia kuehniella, Cadra cautella, Plodia interpunctella, and Galleria mellonella--tracing pachytene bivalents which provide much higher resolution than metaphase chromosomes. In each species, we prepared a W-chromosome painting probe from laser-microdissected W-chromatin of female polyploid nuclei. The Ephestia W-probe was cross-hybridized to chromosomes of the other pyralids to detect common parts of their W chromosomes, while the species-specific W-probes identified the respective W chromosome. This so-called Zoo-FISH revealed a partial homology of W-chromosome regions between E. kuehniella and two other pyralids, C. cautella and P. interpunctella, but almost no homology with G. mellonella. The results were consistent with phylogenetic relationships between the species. We also performed comparative genomic hybridization, which indicated that the W chromosome of C. cautella is composed mainly of repetitive DNA common to both sexes but accumulated in the W chromosome, whereas E. kuehniella, P. interpunctella, and G. mellonella W chromosomes also possess a large amount of female specific DNA sequences, but differently organized. Our results support the hypothesis of the accelerated molecular divergence of the lepidopteran W chromosomes in the absence of meiotic recombination.
大多数鳞翅目昆虫具有WZ/ZZ性染色体系统。我们比较了螟蛾科四个代表物种——地中海粉螟、印度谷螟、一点谷螟和大蜡螟——的W染色体结构，追踪粗线期二价体，其分辨率比中期染色体高得多。在每个物种中，我们从雌性多倍体细胞核的激光显微切割W染色质中制备了W染色体涂染探针。地中海粉螟的W探针与其他螟蛾科昆虫的染色体进行交叉杂交，以检测它们W染色体的共同部分，而物种特异性的W探针则可识别各自的W染色体。这种所谓的动物荧光原位杂交显示，地中海粉螟与另外两种螟蛾科昆虫——印度谷螟和一点谷螟——的W染色体区域存在部分同源性，但与大蜡螟几乎没有同源性。结果与这些物种之间的系统发育关系一致。我们还进行了比较基因组杂交，结果表明，印度谷螟的W染色体主要由两性共有的重复DNA组成，但在W染色体中积累，而地中海粉螟、一点谷螟和大蜡螟的W染色体也拥有大量雌性特异性DNA序列，但组织方式不同。我们的结果支持了在没有减数分裂重组的情况下，鳞翅目昆虫W染色体分子分歧加速的假说。
