Biology subjects

Koshikawa, S.

Publications and source records attributed to Koshikawa, S..

7 recordsLinked to original sources

bioRxiv2023

Cis-regulatory evolution that caused change in wingless expression pattern associated with wing pigmentation pattern of Drosophila

Genetic mechanisms underlying the acquisition of new traits are an important topic in evolutionary developmental biology. Especially, the co-option of important regulatory genes potentially plays an important role in the gain of new traits. However, how the co-option occurs at the sequence level is still elusive. Drosophila guttifera has a unique wing pigmentation pattern and this is newly gained via the evolution of the expression pattern of wingless, which induces the pigmentation pattern formation. In this study, to reveal the changes in the cis-regulatory sequence which caused the co-option of wingless that lead to the expression in a new place, we conducted transgenic EGFP reporter assays of altered cis-regulatory sequences. As a result, the sequence was divided into regions needed to activate expression in the entire wing veins and a region required for repressing expression in excess parts. Comparisons with the homologous sequence of Drosophila melanogaster showed that the repressive function of the cis-regulatory region is also possessed by D. melanogaster while the activating function is newly gained in a lineage leading to D. guttifera. Furthermore, a putative binding site of SMAD transcription factors is shown to be essential for activating expression but also existing in the homologous region of D. melanogaster. Our results suggest that the pre-existing regulatory sequences in the cis-regulatory region coordinate with the newly gained sequences to acquire the new expression pattern of wingless. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

developmental biology↗

bioRxiv2023

Photoreceptor genes in a trechine beetle, Trechiama kuznetsovi, living in the upper hypogean zone

To address how organisms adapt to a new environment, subterranean organisms whose ancestors colonized subterranean habitats from surface habitats have been studied. Photoreception abilities have been shown to have degenerated in organisms living in caves and calcrete aquifers. Meanwhile, the organisms living in a shallow subterranean environment, which are inferred to reflect an intermediate stage in an evolutionary pathway to colonization of a deeper subterranean environment, have not been studied well. In the present study, we examined the photoreception ability in a trechine beetle, Trechiama kuznetsovi, which inhabits the upper hypogean zone and has a vestigial compound eye. By de novo assembly of genome and transcript sequences, we were able to identify photoreceptor genes and phototransduction genes. Specifically, we focused on opsin genes, where one long wavelength opsin gene and one ultraviolet opsin gene were identified. The encoded amino acid sequences had neither a premature stop codon nor a frameshift mutation, and appeared to be subject to purifying selection. Subsequently, we examined the internal structure of the compound eye and nerve tissue in the adult head, and found potential photoreceptor cells in the compound eye and nerve bundle connected to the brain. The present findings suggest that T. kuznetsovi has retained the ability of photoreception. This species represents a transitional stage of vision, in which the compound eye regresses, but it may retains the ability of photoreception using the vestigial eye.

zoology↗

bioRxiv2023

Thermal plasticity of wing spot size in Drosophila guttifera: investigating the relevance to Wingless morphogen

Thermal plasticity of animal color patterns has been studied to investigate the molecular mechanisms of phenotypic plasticity. There are examples in which the formation of color patterns is controlled by a morphogen. The extracellular distribution of a morphogen can be plastic with temperature change. Whether alteration of morphogen distribution with temperature change produces thermal plasticity in color patterns has not been studied. To address this question, polka-dotted wing spots of Drosophila guttifera, whose inducer is wingless morphogen, can be a suitable model system. In this study, we reared D. guttifera at different temperatures to test whether wing spots show thermal plasticity. We found that wing size becomes larger and spot size adjusted with wing size becomes smaller at lower temperatures. We also changed the rearing temperature in the middle of the pupal period and found that the most sensitive developmental period for wing size and spot size is different. The results suggest that developmental mechanisms for the thermal plasticity of wing size and spot size are different. We also found that the most sensitive stage for spot size was part of the pupal period including stages at which wingless is expressed in the polka-dotted pattern. Therefore, it is suggested that temperature change might affect the process of specifying spot areas by Wingless in the extracellular region.

zoology↗

bioRxiv2021

DrosoPhyla: genomic resources for drosophilid phylogeny and systematics

The vinegar fly Drosophila melanogaster is a pivotal model for invertebrate development, genetics, physiology, neuroscience, and disease. The whole family Drosophilidae, which contains over 4000 species, offers a plethora of cases for comparative and evolutionary studies. Despite a long history of phylogenetic inference, many relationships remain unresolved among the groups and genera in the Drosophilidae. To clarify these relationships, we first developed a set of new genomic markers and assembled a multilocus data set of 17 genes from 704 species of Drosophilidae. We then inferred well-supported group and species trees for this family. Additionally, we were able to determine the phylogenetic position of some previously unplaced species. These results establish a new framework for investigating the evolution of traits in fruit flies, as well as valuable resources for systematics.

evolutionary biology↗

bioRxiv2021

The color pattern inducing gene wingless is expressed in specific cell types of campaniform sensilla of a polka-dotted fruit fly, Drosophila guttifera

A polka-dotted fruit fly, Drosophila guttifera, has a unique pigmentation pattern on its wings and is used as a model for evo-devo studies exploring the mechanism of evolutionary gain of novel traits. In this species, a morphogen-encoding gene, wingless, is expressed in species-specific positions and induces a unique pigmentation pattern. To produce some of the pigmentation spots on wing veins, wingless is thought to be expressed in developing campaniform sensilla cells, but it was unknown which of the four cell types there express(es) wingless. Here we show that two of the cell types, dome cells and socket cells, express wingless, as indicated by in situ hybridization together with immunohistochemistry. This is a unique case in which non-neuronal SOP (sensory organ precursor) progeny cells produce Wingless as an inducer of pigmentation pattern formation. Our finding opens a path to clarifying the mechanism of evolutionary gain of a unique wingless expression pattern by analyzing gene regulation in dome cells and socket cells.

developmental biology↗

bioRxiv2020

Sexually monomorphic wing pigmentation pattern does not contribute to mate choice in Drosophila guttifera

In many animal groups, sexually dimorphic ornaments are thought to be evolved by intraspecific competition or mate choice. Some researchers pointed out that sexually monomorphic ornaments could also be evolved by mate choice by both sexes or either sex. Many species of fruit fly have sexually monomorphic wing pigmentation. However, involvement of their sexually monomorphic ornaments in mate choice has not been tested. We aimed to examine whether the sexually monomorphic polka-dotted pattern on wings of Drosophila guttifera contributes to mate choice. Because D. guttifera does not mate in the dark condition at all and courtship sound was not observed, some visual information is likely to be used in mating behaviour. We compared the number of mates between individuals with and without wings, and found that presence of wings influenced mate choice in both sexes. We then compared the number of mates between individuals bearing replaced wings, one group for conspecific D. guttifera wings and another group for heterospecific D. melanogaster wings with no pigmentation pattern. The effect of conspecific/heterospecific wings was only detected in mate choice by females. By comparison between wild-type and black-painted wings, we found no evidence of contribution of wing pigmentation pattern to mate choice in either sex.

animal behavior and cognition↗

bioRxiv2020

Transcriptome analysis reveals evolutionary co-option of neural development and signaling genes for the wing pigmentation pattern of the polka-dotted fruit fly.

How evolutionary novelties have arisen is one of the central questions in evolutionary biology. Pre-existing gene regulatory networks or signaling pathways have been shown to be co-opted for building novel traits in several organisms. However, the structure of entire gene regulatory networks and evolutionary events of gene co-option for emergence of a novel trait are poorly understood. In this study, we used a novel wing pigmentation pattern of the polka-dotted fruit fly, and identified the complete set of genes for pigmentation pattern formation by de novo genome sequencing and transcriptome analyses. In pigmentation areas of wings, 151 genes were positively or negatively regulated by wingless, a master regulator of wing pigmentation. Genes for neural development, Wnt signaling, Dpp signaling, Zinc finger transcription factors, and effectors (such as enzymes) for melanin pigmentation were included among these 151 genes. None of the known regulatory genes that regulate pigmentation pattern formation in other fruit fly species were included. Our results suggest that the novel pigmentation pattern of the polka-dotted fruit fly emerged through multi-step co-options of multiple gene regulatory networks, signaling pathways, and effector genes, rather than recruitment of one large gene circuit.

developmental biology↗