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Osmotic Balance in the Eggs of the Turtle Chelodina rugosa during Developmental Arrest under water

Seymore, R. S., Kennett, Rod M. and Christian, Keith A. (1997). Osmotic Balance in the Eggs of the Turtle Chelodina rugosa during Developmental Arrest under water. Physiological Zoology,70(3):301-306.

Document type: Journal Article
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Title Osmotic Balance in the Eggs of the Turtle Chelodina rugosa during Developmental Arrest under water
Author Seymore, R. S.
Kennett, Rod M.
Christian, Keith A.
Journal Name Physiological Zoology
Publication Date 1997
Volume Number 70
Issue Number 3
ISSN 0031-935X   (check CDU catalogue  open catalogue search in new window)
Start Page 301
End Page 306
Total Pages 6
Place of Publication Chicago
Publisher The University of Chicago Press
HERDC Category C1 - Journal Article (DEST)
Abstract The tropical Australian turtle Chelodina rugosa normally lays its hard-shelled eggs in mud, under shallow freshwater, during the monsoon season. The eggs undergo developmental arrest until the water recedes and oxygen is able to diffuse into the embryo. This period of arrest can exceed 12 wk without embryonic mortality. To understand how the eggs avoid osmotic absorption of water leading to shell rupture and embryonic death, this study investigates the solute concentrations and volumes of the albumen and yolk compartments during submergence in distilled water. The albumen loses considerable sodium through the shell, particularly during the first week, and its osmotic concentration drops from 234 mmol/kg at laying to about 23 mmol/kg. Meanwhile, water from the albumen slowly moves through the vitelline membrane into the yolk compartment, which enlarges at a constant rate until it approaches the inside of the shell at about 22 wk. Osmotic uptake dilutes yolk solutes, decreasing the osmotic concentration from 281 mmol/kg at laying to 132 mmol/kg at 157 d. Loss of embryonic viability is associated with contact of the vitelline membrane with the inside of the shell. The principal adaptation of this species for protracted developmental arrest under water is a vitelline membrane of such low permeability to water that the expansion of the yolk compartment occurs about 10 times more slowly than in other chelonians.
Additional Notes Current title: Physiological and Biochemical Zoology: ecological and evolutionary approaches (ISSN: 1522-2152)
 
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