Cytogenetic Characterization and AFLP-Based Genetic Linkage Mapping for the Butterfly Bicyclus anynana, Covering All 28 Karyotyped Chromosomes
Cytogenetic Characterization and AFLP-Based Genetic Linkage Mapping for the Butterfly Bicyclus anynana, Covering All 28 Karyotyped Chromosomes
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蝴蝶 Bicyclus anynana 的细胞遗传学表征和基于 AFLP 的遗传连锁图谱，涵盖所有 28 条核型染色体
作者：
Arjèn E. van’t Hof;F. Marec;I. Saccheri;P. Brakefield;B. Zwaan
研究背景：尽管Bicyclus anynana在科学上具有重要意义，但其染色体特征却很少受到关注。本研究通过细胞遗传学分析和连锁图谱的方法对该物种的染色体进行了表征。方法/主要发现蝴蝶B的物理基因组特征。通过核型分析和连锁图谱的构建，对Anynana进行了研究。鳞翅目昆虫具有雌性异配子W-Z性染色体系统。B粗线期卵母细胞中的WZ二价体。anynana由一条异常小的异染色质W-染色体组成，Z-染色体包裹在W-染色体周围，因此间期核中的W-体比鳞翅目昆虫通常的小得多。这表明在W-染色体的继发性丢失过程中的一个中间阶段，ZZ/Z性别决定系统。粗线期有两个核仁，分别与常染色体和WZ二价体有关。染色体计数证实n = 28的单倍体数目。 连锁图谱必须考虑到没有交换的女性，我们使用的全同胞杂交设计。我们开发了一种新的方法来确定和排除后代中的非重组无信息的女性遗传成分。利用一种新的方法构建的连锁图谱，该方法仅使用JOINMAP软件进行鳞翅目连锁作图。该方法简化了作图过程，避免了对作图距离的高估，提高了标记相对位置的可靠性。共检测到347个AFLP标记、9个微卫星标记和1个单拷贝核基因，覆盖了28条染色体，定位距离为1354 cM。Tpi在鳞翅目昆虫Z染色体上的保守同线性为B。anynana。结果进行了讨论，在其他映射研究鳞翅目。结论/意义这项研究增加了深入研究的生物体的染色体结构和进化的知识。在更广泛的范围内，它提供了一个深入了解鳞翅目性染色体的进化，它提出了一个更简单，更可靠的方法，连锁作图比鳞翅目至今。
Background The chromosome characteristics of the butterfly Bicyclus anynana, have received little attention, despite the scientific importance of this species. This study presents the characterization of chromosomes in this species by means of cytogenetic analysis and linkage mapping. Methodology/Principal Findings Physical genomic features in the butterfly B. anynana were examined by karyotype analysis and construction of a linkage map. Lepidoptera possess a female heterogametic W-Z sex chromosome system. The WZ-bivalent in pachytene oocytes of B. anynana consists of an abnormally small, heterochromatic W-chromosome with the Z-chromosome wrapped around it. Accordingly, the W-body in interphase nuclei is much smaller than usual in Lepidoptera. This suggests an intermediate stage in the process of secondary loss of the W-chromosome to a ZZ/Z sex determination system. Two nucleoli are present in the pachytene stage associated with an autosome and the WZ-bivalent respectively. Chromosome counts confirmed a haploid number of n = 28. Linkage mapping had to take account of absence of crossing-over in females, and of our use of a full-sib crossing design. We developed a new method to determine and exclude the non-recombinant uninformative female inherited component in offspring. The linkage map was constructed using a novel approach that uses exclusively JOINMAP-software for Lepidoptera linkage mapping. This approach simplifies the mapping procedure, avoids over-estimation of mapping distance and increases the reliability of relative marker positions. A total of 347 AFLP markers, 9 microsatellites and one single-copy nuclear gene covered all 28 chromosomes, with a mapping distance of 1354 cM. Conserved synteny of Tpi on the Z-chromosome in Lepidoptera was confirmed for B. anynana. The results are discussed in relation to other mapping studies in Lepidoptera. Conclusions/Significance This study adds to the knowledge of chromosome structure and evolution of an intensively studied organism. On a broader scale it provides an insight in Lepidoptera sex chromosome evolution and it proposes a simpler and more reliable method of linkage mapping than used for Lepidoptera to date.