Combinatorial expression of ebony and tan generates body color variation from nymph through adult stages in the cricket, Gryllus bimaculatus

• Published in: PloS one Vol. 18; no. 5; p. e0285934
• Main Authors: Inoue, Shintaro, Watanabe, Takahito, Hamaguchi, Taiki, Ishimaru, Yoshiyasu, Miyawaki, Katsuyuki, Nikawa, Takeshi, Takahashi, Akira, Noji, Sumihare, Mito, Taro
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 18-05-2023; Public Library of Science (PLoS)
• Subjects: Adults; Amino acids; Analysis; Animals; Biology and Life Sciences; Biosynthesis; Body composition; Chemical synthesis; Color; Combinatorial analysis; Crickets; CRISPR; Dopamine; Dopamine - metabolism; Embryos; Enzymes; Genes; Genetic research; Genomes; Gryllidae - genetics; Gryllidae - metabolism; Gryllus bimaculatus; Hatching; Identification and classification; Insect Proteins - genetics; Insect Proteins - metabolism; Insects; Males; Melanin; Melanins - genetics; Melanins - metabolism; Molecular weight; Molting; Mutants; Nymph - metabolism; Phenotypes; Phylogenetics; Physical Sciences; Pigments; Proteins; Scientific equipment and supplies industry; Tanning; Japan; United States
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0285934

Insect body colors and patterns change markedly during development in some species as they adapt to their surroundings. The contribution of melanin and sclerotin pigments, both of which are synthesized from dopamine, to cuticle tanning has been well studied. Nevertheless, little is known about how insects alter their body color patterns. To investigate this mechanism, the cricket Gryllus bimaculatus, whose body color patterns change during postembryonic development, was used as a model in this study. We focused on the ebony and tan genes, which encode enzymes that catalyze the synthesis and degradation, respectively, of the precursor of yellow sclerotin N-β-alanyl dopamine (NBAD). Expression of the G. bimaculatus (Gb) ebony and tan transcripts tended to be elevated just after hatching and the molting period. We found that dynamic alterations in the combined expression levels of Gb'ebony and Gb'tan correlated with the body color transition from the nymphal stages to the adult. The body color of Gb'ebony knockout mutants generated by CRISPR/Cas9 systemically darkened. Meanwhile, Gb'tan knockout mutants displayed a yellow color in certain areas and stages. The phenotypes of the Gb'ebony and Gb'tan mutants probably result from an over-production of melanin and yellow sclerotin NBAD, respectively. Overall, stage-specific body color patterns in the postembryonic stages of the cricket are governed by the combinatorial expression of Gb'ebony and Gb'tan. Our findings provide insights into the mechanism by which insects evolve adaptive body coloration at each developmental stage.