Department of Biology, University of Washington, Seattle, Washington, USA.
PLoS Genet. 2009 Nov;5(11):e1000744. doi: 10.1371/journal.pgen.1000744. Epub 2009 Nov 26.
Relatively little is known about the generation of adult form. One complex adult trait that is particularly amenable to genetic and experimental analysis is the zebrafish pigment pattern, which undergoes extensive remodeling during post-embryonic development to form adult stripes. These stripes result from the arrangement of three classes of neural crest-derived pigment cells, or chromatophores: melanophores, xanthophores, and iridophores. Here, we analyze the zebrafish bonaparte mutant, which has a normal early pigment pattern but exhibits a severe disruption to the adult stripe pattern. We show that the bonaparte mutant phenotype arises from mutations in basonuclin-2 (bnc2), encoding a highly conserved, nuclear-localized zinc finger protein of unknown function. We show that bnc2 acts non-autonomously to the melanophore lineage and is expressed by hypodermal cells adjacent to chromatophores during adult pigment pattern formation. In bonaparte (bnc2) mutants, all three types of chromatophores differentiate but then are lost by extrusion through the skin. We further show that while bnc2 promotes the development of two genetically distinct populations of melanophores in the body stripes, chromatophores of the fins and scales remain unaffected in bonaparte mutants, though a requirement of fin chromatophores for bnc2 is revealed in the absence of kit and colony stimulating factor-1 receptor activity. Finally, we find that bonaparte (bnc2) mutants exhibit dysmorphic ovaries correlating with infertility and bnc2 is expressed in somatic ovarian cells, whereas the related gene, bnc1, is expressed within oocytes; and we find that both bnc2 and bnc1 are expressed abundantly within the central nervous system. These findings identify bnc2 as an important mediator of adult pigment pattern formation and identify bonaparte mutants as an animal model for dissecting bnc2 functions.
关于成体形式的产生，我们知之甚少。有一种复杂的成体特征特别适合进行遗传和实验分析，那就是斑马鱼的色素模式，它在胚胎后发育过程中经历了广泛的重塑，形成了成体条纹。这些条纹是由三类神经嵴衍生的色素细胞，即黑素细胞、黄色素细胞和虹彩细胞的排列形成的。在这里，我们分析了斑马鱼 bonaparte 突变体，它具有正常的早期色素模式，但表现出严重的成体条纹模式破坏。我们表明，bonaparte 突变体表型是由 basonuclin-2 (bnc2)突变引起的，bnc2 编码一种高度保守的、核定位的锌指蛋白，其功能未知。我们表明，bnc2 非自主地作用于黑素细胞谱系，并在成体色素模式形成过程中由相邻于色素细胞的真皮细胞表达。在 bonaparte(bnc2)突变体中，所有三种类型的色素细胞都分化了，但随后通过皮肤挤出而丢失。我们进一步表明，虽然 bnc2 促进了体条纹中两种具有遗传差异的黑素细胞群体的发育，但 bonaparte 突变体中的鳍和鳞片的色素细胞不受影响，尽管在 kit 和集落刺激因子-1 受体活性缺失的情况下，fin 色素细胞对 bnc2 的需求被揭示出来。最后，我们发现 bonaparte(bnc2)突变体表现出与不育相关的卵巢畸形，并且 bnc2 在体腔卵巢细胞中表达，而相关基因 bnc1 在卵母细胞中表达；我们还发现 bnc2 和 bnc1 在中枢神经系统中都大量表达。这些发现确定了 bnc2 是成体色素模式形成的重要介质，并确定 bonaparte 突变体是解析 bnc2 功能的动物模型。
