Hemoglobin in the parthenogenetic eggs of <i>Daphnia magna</i>

Abstract

Abstract The hemoglobin (Hb) concentration in a single parthenogenetic egg from Hb‐rich Daphnia magna was about three times that in an egg from a Hb‐poor animal. Hemoglobin‐rich animals first produced Hb‐rich eggs in air‐saturated water. The Hb concentration of the eggs gradually decreased, leading to a decrease in the Hb concentration in hemolymph in adult animals. The P50 values (equilibrium oxygen pressure at half saturation) of solutions of purified Hb were 2.9 and 7.2 torr at 20°C for Hb‐rich and Hb‐poor eggs, respectively. Hemoglobin from the eggs was separated into at least eight Hb components by isoelectric focusing. The pI values (isoelectric point) of the major Hb components of the eggs exceeded those of adult Hb. The relative amounts of Hb components with high pI values in Hb‐rich eggs were higher than those of Hb‐poor eggs. On sodium dodecyl sulfate‐polyacrylamide gel electrophoresis technique (SDS‐PAGE), the Hb from eggs was composed of 37,000 molecular weight subunits.