Biology subjects

Daimon, T.

Publications and source records attributed to Daimon, T..

5 recordsLinked to original sources

bioRxiv2025

Sex-specific doublesex regulation targeting the color-patterning gene h underlies the evolution of wing sexual dimorphism in the harlequin ladybug Harmonia axyridis

Organisms on Earth show various forms of sexual dimorphism, including ornaments, weapon traits, and pheromone glands, which has been acquired through sexual selection during evolution. Although the genetic basis of sexual trait has been investigated in diverse species, its evolutionary origin, evolutionary mode, and evolvability remain poorly understood. To address these issues, we investigated the strain-specific sexual dimorphism in elytral color patterns of the harlequin ladybug, Harmonia axyridis, a species with over 200 color morphs. The most basal Red-nSpots type color morph exhibits sexual dimorphism, whereas other derived color morphs have lost it. To investigate how this loss of sexual dimorphism is associated with the emergence of novel color morphs, we investigated the genetic basis of sexual dimorphism by focusing on the master sex differentiation gene, doublesex (dsx). We show that dsx regulates color pattern dimorphism by negatively modulating black spot size in males. This modulation is primarily mediated by the transcriptional regulation of the color patterning gene, h (Drosophila pannier ortholog). Intraspecific comparative ATAC-seq analysis of the pupal wings revealed that, at the h locus, not the absolute number of Dsx-binding motifs but the proportion of open chromatin regions containing Dsx-binding motifs relative to those lacking such motifs was reduced in strains that had lost sexual dimorphism and acquired novel color patterns, implying that sexual dimorphism evolves based on the balance between novel CREs and Dsx-binding motif density. The present study provides a fundamental molecular framework for understanding how a secondary sexual trait evolves within H. axyridis.

evolutionary biology↗

bioRxiv2023

DIPA-CRISPR gene editing in the yellow fever mosquito Aedes aegypti (Diptera: Culicidae)

Current methods for gene editing in insects rely on embryonic microinjection, which can be challenging for non-specialist laboratories. Recently, an alternative method known as "direct parental" CRISPR (DIPA-CRISPR) was developed. This method involves injecting commercial Cas9 protein and single-guide RNA into adult females, which can efficiently introduce mutations into developing oocytes. However, its versatility has not been fully explored, particularly in insects that have the most derived, polytrophic meroistic ovaries. In this study, we successfully applied DIPA-CRISPR to the yellow fever mosquito Aedes aegypti, which has polytrophic meroistic ovaries. Following adult injection of Cas9 ribonucleoproteins (Cas9 RNPs) targeting the kynurenine 3-monooxygenase gene, we recovered gene-edited G0 individuals. Injection at 24 h after blood-feeding resulted in the highest gene editing efficiency (3.5%), confirming that a key parameter of DIPA-CRISPR is the stage in which the adult females are injected. Together with our previous study, we demonstrated that DIPA-CRISPR is applicable to all three types of insect ovaries (i.e., panoistic, telotrophic, and polytrophic), which indicates that DIPA-CRISPR is a generalizable approach for insect gene editing.

genetics↗

bioRxiv2022

Reduction of embryonic E93 expression as a key factor for the evolution of insect metamorphosis

The early embryo of the cockroach Blattella germanica exhibits high E93 expression. In general, E93 triggers adult morphogenesis during postembryonic development, but in the cockroach E93 is also crucial in early embryogenesis. Moreover, the embryonic levels of E93 expression are high in hemimetabolan insects, while in holometabolans they are very low. They are also low in Thysanoptera and in Hemiptera Sternorrhyncha with postembryonic quiescent stages, as well as in Odonata, the nymph of which is very different from the adult. In ametabolans, such as the Zygentoma Thermobia domestica, E93 expression levels are very high in the early embryo, whereas during postembryonic development they are medium and relatively constant. Given that embryogenesis of hemimetabolans yields an adultiform nymph, we speculate that E93 plays some sort of adult triggering role in the embryo of these species. We conjecture that the reduction of E93 transcript levels in the embryo has been instrumental in the evolution of insect metamorphosis. The suppression of E93 expression during the nymphal period, and its concentration in the preadult stage, is consubstantial with the emergence of hemimetaboly. As such, attenuation of E93 expression in the embryo could have resulted in a larval genetic program and the emergence of holometaboly. Independent decreases of E93 expression in the embryo of Odonata, Thysanoptera, and different groups of Hemiptera Sternorrhyncha would have allowed the development of modified juvenile stages adapted to specific ecophysiological conditions.

developmental biology↗

bioRxiv2021

Pathogen-derived 9-methyl sphingoid base is perceived by a lectin receptor kinase in Arabidopsis

In plants, many invading microbial pathogens are recognized by cell-surface pattern recognition receptors (PRRs), inducing defense responses; yet how PRRs perceive pathogen sphingolipids remains unclear. Here, we show that the ceramide Pi-Cer D from a plant pathogenic oomycete Phytophthora infestans triggers defense responses in Arabidopsis. Pi-Cer D is cleaved by an Arabidopsis apoplastic ceramidase, NCER2, and the resulting 9-methyl-branched sphingoid base is recognized by a plasma membrane lectin receptor-like kinase, RDA2. Importantly, 9-methyl-branched sphingoid base, which is unique to microbes, induces plant immune responses by interacting with RDA2. Loss of RDA2 or NCER2 function compromised Arabidopsis resistance against an oomycete pathogen, indicating that these are crucial for defense. We provide new insights that help elucidate the recognition mechanisms of pathogen-derived lipid molecules in plants. One Sentence SummaryOomycete-derived ceramide is cleaved into sphingoid base by ceramidase and recognized by an Arabidopsis receptor kinase.

plant biology↗

bioRxiv2021

Pheromone binding protein shapes olfactory temporal resolution

Male moths are capable of orienting towards conspecific females using sex pheromones. Since pheromones are distributed as discontinuous plumes owing to air turbulence, tracking intermittent stimuli with high temporal resolution is suggested to be important for efficient localisation. Here, using a pheromone binding protein (BmPBP1) knockout silkmoth, we revealed that the loss of functional pheromone binding protein altered antennal response kinetics resulting in reduced temporal resolution to intermittent pheromone stimuli on the antennae. Behavioural analysis revealed that BmPBP1-knockout males exhibited significantly less straight walking, which occurs when detecting pheromone stimuli, especially to high frequency stimuli. Accordingly, BmPBP1-knockout males took a significantly longer time to locate pheromone sources and females than did wild-type males. Together, BmPBP1 plays a critical role in determining temporal antennal response kinetics and that an appropriate range of temporal sensory and behavioural resolutions is essential for tracking pheromone plumes for efficient pheromone source localisation in the silkmoth.

neuroscience↗