Language：English   Publishing type：Research paper (scientific journal)  

Limb reduction has occurred multiple times in tetrapod history. Among ratites, wing reductions range from mild vestigialization to complete loss, with emus (Dromaius novaehollandiae) serving as a model for studying the genetic mechanisms behind limb reduction. Here, we explore the developmental mechanisms underlying wing reduction in emu. Our analyses reveal that immobilization resulting from the absence of distal muscles contributes to skeletal shortening, fusion and left-right intraindividual variation. Expression analysis and single cell-RNA sequencing identify muscle progenitors displaying a dual lateral plate mesodermal and myogenic signature. These cells aggregate at the proximal region of wing buds and undergo cell death. We propose that this cell death, linked to the lack of distal muscle masses, underlines the morphological features and variability in skeletal elements due to reduced mechanical loading. Our results demonstrate that differential mobility during embryonic development may drive morphological diversification in vestigial structures.

DOI： 10.1038/s41467-024-52203-x

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

The medaka contains seven zic genes, two of which, zic1 and zic4, have been studied extensively. The analyses are mainly based on the double anal fin (Da) mutant, which was isolated from the wild. Da is an enhancer mutant of zic1/zic4, and the expression of zic1/zic4 is specifically lost in the dorsal half of the somites, which leads to a mirror-image duplication of the ventral half across the lateral midline from larva to adult. The studies of medaka Da give us important insights into the function of zic1/zic4 in mesodermal tissues and also the mechanism of dorsoventral patterning in the vertebrate trunk region occurring during late development, which is a long-standing mystery in developmental biology. In this chapter, we introduce genomic organization of medaka zic genes and discuss their function, mainly focusing on zic1 and zic4 in dorsoventral patterning of the trunk region and possible connections to human congenital disorders.

DOI： 10.1007/978-981-10-7311-3_8

PubMed

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Teleost fish exhibit remarkable diversity in morphology, such as fins and coloration, particularly on the dorsal side. These structures are evolutionary adaptive because their back is highly visible to other individuals. However, owing to the late phenotypic appearance (from larva to adult) and lack of appropriate mutants, the genetic mechanisms that regulate these dorsoventrally asymmetric external patterns are largely unknown. To address this, we have analyzed the spontaneous medaka mutant Double anal fin (Da), which exhibits a mirror-image duplication of the ventral half across the lateral midline from larva to adult. Da is an enhancer mutant for zic1 and zic4 in which their expression in dorsal somites is lost. We show that the dorsoventral polarity in Da somites is lost and then demonstrate using transplantation techniques that somites and their derived tissues globally determine the multiple dorsal-specific characteristics of the body (fin morphology and pigmentation) from embryo to adult. Intriguingly, the zic1/zic4 expression in the wild type persists throughout life in the dorsal parts of somite derivatives, i.e. the myotome, dermis and vertebrae, forming a broad dorsal domain in the trunk. Comparative analysis further implies a central role for zic1/zic4 in morphological diversification of the teleost body. Taken together, we propose that the teleost trunk consists of dorsal/ventral developmental modules and that zic1/zic4 in somites function as selector genes in the dorsal module to regulate multiple dorsal morphologies.

DOI： 10.1242/dev.088567

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

The vertebrate mineralized skeleton is known to have first emerged as an exoskeleton that extensively covered the fossil jawless fish. The evolutionary origin of this exoskeleton has long been attributed to the emergence of the neural crest, but experimental evaluation for this is still poor. Here we determine the embryonic origin of scales and fin rays of medaka (teleost trunk exoskeletons) by applying long-term cell labelling methods, and demonstrate that both tissues are mesodermal in origin. Neural crest cells, however, fail to contribute to these tissues. This result suggests that the trunk neural crest has no skeletogenic capability in fish, instead highlighting the dominant role of the mesoderm in the evolution of the trunk skeleton. This further implies that the role of the neural crest in skeletogenesis has been predominant in the cephalic region from the early stage of vertebrate evolution.

DOI： 10.1038/ncomms2643

PubMed

Language：English   Publishing type：Research paper (scientific journal)  

Teleosts have an asymmetrical caudal fin skeleton formed by the upward bending of the caudal-most portion of the body axis, the ural region. This homocercal type of caudal fin ensures powerful and complex locomotion and is regarded as one of the most important innovations for teleosts during adaptive radiation in an aquatic environment. However, the mechanisms that create asymmetric caudal fin remain largely unknown. The spontaneous medaka (teleost fish) mutant, Double anal fin (Da), exhibits a unique symmetrical caudal skeleton that resembles the diphycercal type seen in Polypterus and Coelacanth. We performed a detailed analysis of the Da mutant to obtain molecular insight into caudal fin morphogenesis. We first demonstrate that a large transposon, inserted into the enhancer region of the zic1 and zic4 genes (zic1/zic4) in Da, is associated with the mesoderm-specific loss of their transcription. We then show that zic1/zic4 are strongly expressed in the dorsal part of the ural mesenchyme and thereby induce asymmetric caudal fin development in wild-type embryos, whereas their expression is lost in Da. Comparative analysis further indicates that the dorsal mesoderm expression of zic1/zic4 is conserved in teleosts, highlighting the crucial role of zic1/zic4 in caudal fin morphogenesis.

DOI： 10.1016/j.cub.2012.01.063

PubMed

Event date： 2021.12

Language：Japanese   Presentation type：Poster presentation  

Venue：パシフィコ横浜   Country：Japan  

Event date： 2020.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Kumamoto   Country：Japan  

Event date： 2020.3 - 2020.4

Language：English   Presentation type：Oral presentation (general)  

Venue：Universidad Peruana Cayetano Heredia (UPCH), Lima   Country：Peru  

Event date： 2019.7

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：東京慈恵会医科大学   Country：Japan  

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Venue：International House Osaka, Osaka   Country：Japan  

Event date： 2017.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Peter Giligan Centre for Research and Learning   Country：Canada  

Event date： 2012.9

Language：English   Presentation type：Poster presentation  

Venue：Kyoto University, Kyoto   Country：Japan  

Event date： 2012.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学   Country：Japan  

Event date： 2012.7

Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：National University of Singapore   Country：Singapore  

Event date： 2011.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Okinawa Convention Center, Okinawa   Country：Japan  

Event date： 2010.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：八王子セミナーハウス   Country：Japan  

Event date： 2010.8

Language：English   Presentation type：Poster presentation  

Venue：Albuquerque Convention Center, New Mexico   Country：United States  

Event date： 2010.6

Language：English   Presentation type：Poster presentation  

Venue：Kyoto International Conference Center, Kyoto   Country：Japan  

Event date： 2009.9

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：静岡グランシップ   Country：Japan  

Event date： 2009.5

Language：English   Presentation type：Poster presentation  

Venue：Toki Messe, Niigata   Country：Japan  

Event date： 2009.1

Language：Japanese   Presentation type：Poster presentation  

Venue：東京大学   Country：Japan  

Event date： 2008.9

Language：Japanese   Presentation type：Poster presentation  

Venue：岡崎カンファレンスセンター   Country：Japan  

Event date： 2008.5

Language：English   Presentation type：Poster presentation  

Venue：Tokushima Arts Foundation for Culture, Tokushima   Country：Japan  

Country：Japan