QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online February 27, 2009
Journal of Experimental Biology 212, 778-784 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.026575

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rombough, P. Articles by Drader, H. Search for Related Content PubMed Articles by Rombough, P. Articles by Drader, H. Social Bookmarking                         What's this?

Hemoglobin enhances oxygen uptake in larval zebrafish (Danio rerio) but only under conditions of extreme hypoxia

Peter Rombough^* and Holly Drader

Department of Biology, Brandon University, Brandon, MB, Canada R7A 4X8

^* Author for correspondence (e-mail: rombough{at}brandonu.ca)

Accepted 16 December 2008

The role of hemoglobin (Hb) in O₂ uptake by zebrafish larvae ranging in age from 5 to 42 days postfertilization was assessed under conditions of normoxia, moderate hypoxia and extreme hypoxia. This was achieved by exposing larvae with and without functional Hb to continuously declining oxygen levels (P_O2) in closed-system respirometers. Exposure to 5% CO for 2–4 h was used to render Hb effectively non-functional in terms of its ability to transport O₂. Routine metabolic rate (r_O2), critical dissolved oxygen level (P_c) and residual oxygen level (P_r) were determined and used, respectively, as indicators of response in normoxia, moderate hypoxia and extreme hypoxia. r_O2 was defined as the average rate of O₂ uptake before O₂ became limiting (i.e. at high P_O2s). P_c is the P_O2 at which r_O2 first becomes O₂-limited and P_r is the P_O2 below which larvae are no longer able to extract O₂ from the ambient medium. CO poisoning had no significant impact on r_O2 or P_c at any age, indicating that the lack of functional Hb does not impair routine O₂ usage in normoxia or at moderate levels of hypoxia [down to at least 25–50 torr (1 torr0.133 kPa), depending on age]. P_r, however, was significantly lower overall for control larvae (6.7±1.1 torr; mean ± 95%CI) than for CO-poisoned larvae (11.2±2.1 torr). It would appear that the presence of functional Hb allows zebrafish larvae to extract O₂ from water down to lower P_O2s under conditions of extreme hypoxia. This is the first documented (as opposed to inferred) benefit of Hb in developing zebrafish. However, given the relatively small magnitude of the effect it is unclear if this benefit on its own is sufficient to balance the costs associated with Hb production and maintenance.

Key words: zebrafish, Danio rerio, hemoglobin, larva, O₂, aerobic metabolism, cost–benefit analysis

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				K. M. Gilmour, K. Thomas, A. J. Esbaugh, and S. F. Perry Carbonic anhydrase expression and CO2 excretion during early development in zebrafish Danio rerio J. Exp. Biol., December 1, 2009; 212(23): 3837 - 3845. [Abstract] [Full Text] [PDF]

				S. L. Steele, K. H. A. Lo, V. W. T. Li, S. H. Cheng, M. Ekker, and S. F. Perry Loss of M2 muscarinic receptor function inhibits development of hypoxic bradycardia and alters cardiac {beta}-adrenergic sensitivity in larval zebrafish (Danio rerio) Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2009; 297(2): R412 - R420. [Abstract] [Full Text] [PDF]