University Of Tasmania

File(s) under permanent embargo

A functional shift of urea-producing site from extraembryonic yolk sac to liver in the developing embryos of two oviparous cartilaginous fishes

conference contribution
posted on 2023-05-24, 13:40 authored by Tagaki, W, Kajimura, M, Tanaka, H, Bell, JD, Hyodo, S
For adaptation to high-osmolality marine environment, cartilaginous fish retain a high systemic concentration of urea. Although the composition of embryonic body fluid was similar to that in adult fish, urea-producing organ has not been identified in developing embryo. Therefore, we investigated the mRNA expression profiles of ornithine urea cycle (OUC) enzymes in two oviparous species. The expression of OUC enzyme genes was detected in the embryonic body, and remarkably increased to hatching, presumably due to the liver growth. The mRNA expression was also found in extraembryonic yolk sac membrane (YSM). The mRNA level of rate-limiting carbamoyl phosphate synthetase III was much higher in the YSM than that in the embryonic body during early stages of development. Our results demonstrate that the YSM makes an important contribution to the ureosmotic strategy of oviparous embryos, and that a functional shift of urea-producing site from YSM to embryonic liver occurs during the development.


Publication title

Abstract Book for the International Congress on the Biology of Fish


D MacKinlay




Institute for Marine and Antarctic Studies

Event title

The International Congress on the Biology of Fish 2014

Event Venue

Edinburgh, Scotland

Date of Event (Start Date)


Date of Event (End Date)


Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the biological sciences

Usage metrics

    University Of Tasmania