title: A Pathway Analysis of Melanin Patterning in a Hemimetabolous Insect.
abstract: 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.
authors.affiliation: Biological Sciences Department, Wayne State University, Detroit, Michigan 48202.
authors.forename: Jin
authors.initials: J
authors.lastname: Liu
authors.affiliation: Biological Sciences Department, Wayne State University, Detroit, Michigan 48202.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Lemonds
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802.
authors.forename: James H
authors.initials: JH
authors.lastname: Marden
authors.affiliation: Biological Sciences Department, Wayne State University, Detroit, Michigan 48202 apopadic@biology.biosci.wayne.edu.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Popadić
mesh_terms: D000818:Animals; D017344:Genes, Insect; D006430:Hemiptera / Q000235:genetics / Q000378:metabolism*; D008543:Melanins / Q000235:genetics / Q000378:metabolism*; D010858:Pigmentation / Q000235:genetics*
chemical_list: D008543:Melanins
keywords: Oncopeltus fasciatus; insect pigmentation; melanin patterning; melanin suppressors; melanin-promoting factors