Oxygen transport efficiency of multiple-component hemoglobin in Daphnia magna
- 1 December 1994
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Zoology
- Vol. 72 (12) , 2169-2171
- https://doi.org/10.1139/z94-289
Abstract
The Adair constants for Daphnia magna hemoglobin (Hb) oxygen equilibrium curves (OECs) were determined, and the fractional oxygen saturation (Y) was differentiated in terms of partial O2 pressure (p), for Hb-rich (YR) and for Hb-poor (YP) animals. Y′ (dY/dp), which depends on loading and unloading p values of Hb, is used to estimate O2 transport efficiency. The ratio of the Y′ values (Y′R/Y′P) peaked (2.9) at a value close to the p50 of HbR. Using two OECs (YI and YII) for monocomponent human adult Hb A, which have similar O2 affinities to HbR and HbP, respectively, a markedly high ratio of differential coefficients (Y′I/Y′II) was obtained. It is therefore considered that the occurrence of multiple Hb's showing an inverse correlation between Hb concentration and p50, as in D. magna, minimizes the total Hb concentration required for adaptation to a wide range of O2 conditions.Keywords
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