Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
Chromosome Res. 2009;17(8):1015-24. doi: 10.1007/s10577-009-9095-1. Epub 2009 Nov 20.
The cane toad (Bufo marinus) is one of the most notorious animal pests encountered in Australia. Members of the genus Bufo historically have been regarded as having genotypic sex determination with male homogamety/female heterogamety. Nevertheless, as with many toads, karyotypic analyses of the cane toad have so far failed to identify heteromorphics sex chromosomes. In this study, we used comparative genomic hybridization, reverse fluorescence staining, C-banding, and morphometric analyses of chromosomes to characterize sex chromosome dimorphism in B. marinus. We found that females consistently had a length dimorphism associated with a nucleolus organizer region (NOR) on one of the chromosome 7 pair. A strong signal over the longer NOR in females, and the absence of a signal in males indicated sex-specific DNA sequences. All females were heterozygous and all males homozygous, indicating a ZZ/ZW sex chromosomal system. Our study confirms the existence of sex chromosomes in this species. The ability to reliably identify genotypic sex of cane toads will be of value in monitoring and control efforts in Australia and abroad.
蔗蟾蜍（Bufo marinus）是澳大利亚最著名的动物害虫之一。Bufo 属的成员历史上被认为具有基因型性别决定，雄性同型性/雌性异型性。然而，与许多蟾蜍一样，迄今为止，对蔗蟾蜍的染色体分析未能确定异型性的性染色体。在这项研究中，我们使用比较基因组杂交、反向荧光染色、C 带和染色体形态计量分析来描述 B. marinus 的性染色体二态性。我们发现，雌性动物 consistently 存在与第 7 对染色体上的一个核仁组织区域（NOR）相关的长度二态性。雌性动物的较长 NOR 上有强烈的信号，而雄性动物则没有信号，表明存在特定于性别的 DNA 序列。所有雌性动物均为杂合子，所有雄性动物均为纯合子，表明存在 ZZ/ZW 性染色体系统。我们的研究证实了该物种存在性染色体。能够可靠地识别蔗蟾蜍的基因型性别将对澳大利亚和国外的监测和控制工作具有重要价值。
