Identification of Hox genes and their expression profiles during embryonic development of the emerging model organism, Macrobrachium olfersii

Abstract

Hox genes encode transcription factors that specify the body segment identity during development, including crustaceans, such as amphipods and decapods, that possess a remarkable diversity of segments and specialized appendages. In amphipods, alterations of specialized appendages have been obtained using knockout experiment of Hox genes, which suggests that these genes are involved in the evolution of morphology within crustaceans. However, studies of Hox genes in crustaceans have been limited to a few species. Here, we identified the homeodomain of nine Hox genes: labial (lab), proboscipedia (pb), Deformed (Dfd), Sex combs reduced (Scr), fushi tarazu (ftz), Antennapedia (Antp), Ultrabithorax (Ubx), abdominal‐A (abdA), and Abdominal‐B (AbdB), and evaluated their expression by RT‐qPCR and RT‐PCR in the ovary, during embryonic development, and at the first larval stage (Zoea I) of the decapod Macrobrachium olfersii. The transcript levels of lab, Dfd, and ftz decreased and transcripts of pb, Scr, Antp, Ubx, abdA, and AbdB increased during embryonic development. Hox genes were expressed in mature ovaries and Zoea I larval stages, except Scr and ftz, respectively. In addition, isoforms of Dfd, Scr, Ubx, and abdA, which have been scarcely reported in crustaceans, were described. New partial sequences of 87 Hox genes from other crustaceans were identified from the GenBank database. Our results are interesting for future studies to determine the specific function of Hox genes and their isoforms in the freshwater prawn M. olfersii and to contribute to the understanding of the diversity and evolution of body plans and appendages in Crustaceans.

Comparative genomics of Hox and ParaHox genes among major lineages of Branchiopoda with emphasis on tadpole shrimps

“…Providing highquality genomic resources for other Branchiopoda species is also fundamental to unravel the mechanism underlying the outstanding biological and life history trait diversity of this tiny clade of crustaceans: for example, it would be useful to include non-Daphnia Cladocera and other Anostraca species in such comparative studies which may reveal more peculiar genome and HPHG dynamics. Hopefully, this characterization of HPHGs in novel branchiopod species, together with growing comparative data from other Pancrustacea lineages (e.g., Jaramillo et al, 2022), will also empower functional studies on these organisms to better understand how the evolution of HPHG sequences and regulatory pathways may have contributed to the diversification of Pancrustacea body plans and genome architectures.…”