Author:
Braun M. H.,Steele S. L.,Ekker M.,Perry S. F.
Abstract
Injection of antisense oligonucleotide morpholinos to elicit selective gene knockdown of ammonia (Rhag, Rhbg, and Rhcg1) or urea transporters (UT) was used as a tool to assess the relative importance of each transporter to nitrogen excretion in developing zebrafish ( Danio rerio). Knockdown of UT caused urea excretion to decrease by ∼90%, whereas each of the Rh protein knockdowns resulted in an ∼50% reduction in ammonia excretion. Contrary to what has been hypothesized previously for adult fish, each of the Rh proteins appeared to have a similar effect on total ammonia excretion, and thus all are required to facilitate normal ammonia excretion in the zebrafish larva. As demonstrated in other teleosts, zebrafish embryos utilized urea to a much greater extent than adults and were effectively ureotelic until hatching. At that point, ammonia excretion rapidly increased and appeared to be triggered by a large increase in the mRNA expression of Rhag, Rhbg, and Rhcg1. Unlike the situation in the adult pufferfish ( 35 ), the various transporters are not specifically localized to the gills of the developing zebrafish, but each protein has a unique expression pattern along the skin, gills, and yolk sac. This disparate pattern of expression would appear to preclude interaction between the Rh proteins in zebrafish embryos. However, this may be a developmental feature of the delayed maturation of the gills, because as the embryos matured, expression of the transporters in and around the gills increased.
Publisher
American Physiological Society
Reference61 articles.
1. Alsop DH, Wood CM.The interactive effects of feeding and exercise on oxygen consumption, swimming performance and protein usage in juvenile rainbow trout.J Exp Biol200: 2337–2346, 1997.
2. Avent ND, Madgett TE, Lee ZE, Head DJ, Maddocks DG, Skinner LH.Molecular biology of Rh proteins and relevance to molecular medicine.Expert Rev Mol Med8: 1–20, 2006.
3. O2 consumption and heart rate in developing zebrafish (Danio rerio): influence of temperature and ambient O2
4. Comparative biochemistry of urea synthesis. 3. Activities of urea cycle enzymes in various higher and lower vertebrates
5. Chadwick TD, Wright PA.Nitrogen excretion and expression of urea cycle enzymes in the Atlantic cod (Gadus morhual.): a comparison of early life stages with adults.J Exp Biol202: 2653–2662, 1999.
Cited by
122 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献