BRIEF RESEARCH REPORT article
Front. Cell Dev. Biol.
Sec. Evolutionary Developmental Biology
Volume 13 - 2025 | doi: 10.3389/fcell.2025.1667637
The subfunctionalization of shox and shox2 paralogs in shark highlights both shared and distinct developmental mechanisms of branchial arches and fins
Provisionally accepted
Galina V. Ermakova1,2
Irina V. Meyntser3
Vassily A. Lyubetsky4,5
Andrey G. Zaraisky1,2,6,7,8,9
Andrey V. Bayramov1,2,6,7*- 1Institute of Bioorganic Chemistry (RAS), Moscow, Russia
- 2FBGUN Institut bioorganiceskoj himii im akademikov M M Semakina i U A Ovcinnikova Rossijskoj akademii nauk, Moscow, Russia
- 3Mosqvarium Center for Oceanography and Marine Biology, Moscow, Russia
- 4Institut problem peredaci informacii imeni A A Harkevica RAN, Moscow, Russia
- 5Institute for Information Transmission Problems of the Russian Academy of Sciences (Kharkevich Institute), Moscow, Russia
- 6FGBUN Institut biologii razvitia imeni N K Kol'cova Rossijskoj akademii nauk, Moscow, Russia
- 7Koltzov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
- 8Rossijskij nacional'nyj issledovatel'skij medicinskij universitet imeni N I Pirogova, Moscow, Russia
- 9Pirogov Russian National Research Medical University, Moscow, Russia
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The genomes of most gnathostomes contain two paralogs of the shox gene, shox and shox2, both of which are implicated in the development of two key morphological innovations: the jaw apparatus derived from the branchial arches and the paired appendages, whose evolutionary origins remain debated. Here, we investigate the expression patterns of shox and shox2 paralogs in the gray bamboo shark (Chiloscyllium griseum), a representative of Chondrichthyes, a basally divergent gnathostome lineage. The paired fins of cartilaginous fishes are considered a basal model for gnathostome appendages. Our findings suggest spatial subfunctionalization of the shox and shox2 genes. Specifically, shox is expressed in the mandibular and branchial arches, as well as in paired and unpaired fins, indicating shared developmental mechanisms among these structures. In contrast, shox2 expression is predominantly restricted to paired fins, highlighting distinct developmental features that differentiate them from the evolutionarily older median fins.
Keywords: SHOX, Shox2, shark, Median fins, Paired fins, Branchial arches
Received: 16 Jul 2025; Accepted: 09 Sep 2025.
Copyright: © 2025 Ermakova, Meyntser, Lyubetsky, Zaraisky and Bayramov. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Andrey V. Bayramov, Institute of Bioorganic Chemistry (RAS), Moscow, Russia
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