Liu Jin, Lemonds Thomas R, Marden James H, Popadić Aleksandar
Biological Sciences Department, Wayne State University, Detroit, Michigan 48202.
Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802.
Genetics. 2016 May;203(1):403-13. doi: 10.1534/genetics.115.186684. Epub 2016 Mar 16.
Diversity in insect pigmentation, encompassing a wide range of colors and spatial patterns, is among the most noticeable features distinguishing species, individuals, and body regions within individuals. In holometabolous species, a significant portion of such diversity can be attributed to the melanin synthesis genes, but this has not been formally assessed in more basal insect lineages. Here we provide a comprehensive analysis of how a set of melanin genes (ebony, black, aaNAT, yellow, and tan) contributes to the pigmentation pattern in a hemipteran, Oncopeltus fasciatus For all five genes, RNA interference depletion caused alteration of black patterning in a region-specific fashion. Furthermore, the presence of distinct nonblack regions in forewings and hindwings coincides with the expression of ebony and aaNAT in these appendages. These findings suggest that the region-specific phenotypes arise from regional employment of various combinations of the melanin genes. Based on this insight, we suggest that melanin genes are used in two distinct ways: a "painting" mode, using predominantly melanin-promoting factors in areas that generally lack black coloration, and, alternatively, an "erasing" mode, using mainly melanin-suppressing factors in regions where black is the dominant pigment. Different combinations of these strategies may account for the vast diversity of melanin patterns observed in insects.
昆虫色素沉着的多样性，涵盖了广泛的颜色和空间模式，是区分物种、个体以及个体内身体区域的最显著特征之一。在全变态昆虫物种中，这种多样性的很大一部分可归因于黑色素合成基因，但在更基础的昆虫谱系中尚未对此进行正式评估。在这里，我们全面分析了一组黑色素基因（乌木色基因、黑色基因、芳香族氨基酸脱羧酶基因、黄色基因和棕褐色基因）如何影响半翅目昆虫——烟草天蛾的色素沉着模式。对于所有这五个基因，RNA干扰敲除以区域特异性方式导致黑色图案发生改变。此外，前翅和后翅中不同的非黑色区域与这些附肢中乌木色基因和芳香族氨基酸脱羧酶基因的表达一致。这些发现表明，区域特异性表型源于黑色素基因各种组合的区域化应用。基于这一见解，我们认为黑色素基因有两种不同的使用方式：一种是“绘画”模式，主要在通常缺乏黑色色素沉着的区域使用促进黑色素生成的因子；另一种是“擦除”模式，主要在以黑色为主要色素的区域使用抑制黑色素生成的因子。这些策略的不同组合可能解释了在昆虫中观察到的黑色素模式的巨大多样性。
