Biology subjects

Komata, S.

Publications and source records attributed to Komata, S..

2 recordsLinked to original sources

bioRxiv2023

Molecular mechanisms underlying the formation of larval green color and camouflage patterns in swallowtail butterfly, Papilio memnon

Insects have various strategies like mimicry or camouflage to avoid predation. Swallowtail butterfly larvae switch from a black and white pattern mimicking bird droppings to a green camouflage pattern in the fifth (final) instar. This larval pattern switch is regulated during the juvenile hormone (JH)-sensitive period, when JH titer declines rapidly, and clawless (cll), abdominal-A (abd-A), and Abdominal-B (Abd-B) function during this period. However, the molecular mechanism behind the background green color, a crucial aspect of the camouflage pattern, remains poorly understood. Here, we used Papilio memnon, which switches to the camouflage pattern in the fifth instar but is greenish from the third instar, to investigate the mechanism of camouflage pattern formation, particularly the larval green coloration. Through RNA sequencing, we found that BBPs forming a gene cluster are upregulated in the green regions of P. memnon larvae during the fourth instar, whereas P. xuthus larvae, which have not yet turned green, showed minimal BBPs expression. When BBP1 and BBP2, which were particularly highly expressed, were knocked down by RNAi, there was a phenotypic change in green to yellow in both fourth and fifth instar larvae. Expression analysis and knockdown experiments were conducted also for JHBP, which had been previously reported, and confirmed that it is involved in the synthesis of yellow pigment. Furthermore, knockdown of Ubx resulted in no phenotypic change in fourth instar larvae, but in fifth instar larvae, the eyespots pattern characteristic of the camouflage pattern almost entirely disappeared, suggesting that Ubx is also functional only during JH-sensitive period. Our results indicate that the switch from mimetic to camouflage patterns resulted from the function of cll, abd-A, Abd-B, and Ubx prepatterning genes during the JH-sensitive period. And the increased expression of BBPs and JHBPs, independent of the JH-sensitive period, contributed to the development of green coloration.

molecular biology↗

bioRxiv2022

Functional involvement of multiple genes as members of the supergene unit in the female-limited Batesian mimicry of Papilio polytes

Supergenes are sets of genes and genetic elements that are inherited like a single gene and control complex adaptive traits, but their functional roles and units are poorly understood. In Papilio polytes, female-limited Batesian mimicry is thought to be regulated by a ~130kb inversion region (highly diversified region: HDR) containing three genes, UXT, U3X and doublesex (dsx) which switches non-mimetic and mimetic types. To determine the functional unit, we here performed electroporation-mediated RNAi analyses (and further Crispr/Cas9 for UXT) of genes within and flanking the HDR in pupal hindwings. We first clarified that non-mimetic dsx-h had a function to switch from male to non-mimetic female and only dsx-H isoform 3 had an important function in the formation of mimetic traits. Next, we found that UXT was involved in making mimetic type pale-yellow spots and adjacent gene sir2 removed excess red spots in hindwings, both of which refine more elaborate mimicry. Furthermore, downstream gene networks of dsx, U3X and UXT screened by RNA sequencing showed that U3X upregulated dsx expression and repressed UXT expression. These findings demonstrate that a set of multiple genes, not only inside but also flanking HDR, can function as supergene members, which extends the definition of supergene unit than we considered before. Also, our results indicate that dsx-H functions as the switching gene and some other genes such as UXT and sir2 within the supergene unit work as the modifier gene. Article summarySupergenes are thought to control complex adaptive traits, but their detailed function are poorly understood. In Papilio polytes, female-limited Batesian mimicry is regulated by an ~130kb inversion region (highly divergent region: HDR) containing three genes. Our functional analysis showed that doublesex switches the mimicry polymorphism, and that an inside gene UXT and an outside gene sir2 to the HDR work to refine more elaborate mimicry. We here succeed in defining the unit of mimicry supergene and some novel modifier genes.

genetics↗