Changes in osmotic and ionic concentrations in the hemolymph of Macrobrachium rosenbergii exposed to varying salinities and correlation to ionic and crystalline composition of the cuticle

Osmotic and ionic regulatory ability were examined in the giant freshwater prawn, Macrobrachium rosenbergii in response to varying salinities. In freshwater, and under conditions of low salinity, hemolymph osmolality was maintained around 450 mOsm. Under high salinity, osmolality values increased in...

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Published in:Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 1998-04, Vol.119 (4), p.941-950
Main Authors: Wilder, Marcy N, Ikuta, Kazumasa, Atmomarsono, Muharijadi, Hatta, Tamao, Komuro, Kosei
Format: Article
Language:English
Subjects:
Brackish
Calcite
Calcium carbonate
Carapace
Cuticle
Freshwater
Ionic regulation
Macrobrachium rosenbergii
Osmoregulation
Prawns
α-Chitin
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Summary:Osmotic and ionic regulatory ability were examined in the giant freshwater prawn, Macrobrachium rosenbergii in response to varying salinities. In freshwater, and under conditions of low salinity, hemolymph osmolality was maintained around 450 mOsm. Under high salinity, osmolality values increased in a time-wise manner until reaching levels of the surrounding rearing water. Changes in sodium concentration generally paralleled osmotic change, and potassium and magnesium concentrations increased upon exposure to extremely high salinity. In contrast, total calcium concentration was maintained at high levels regardless of salinity treatment. Examination of crystalline structure and ionic composition of the cuticle revealed that it was comprised principally of an α-chitin-like material, and calcite (calcium carbonate). Calcite accounted for 25% of total bulk weight in freshwater, while sodium, potassium and magnesium constituents combined comprised less than 2.5% of this total. Although sodium, potassium and magnesium contents increased nearly 2-fold in response to changing salinity, calcium levels remained relatively constant.
ISSN:1095-6433
1531-4332
DOI:10.1016/S1095-6433(98)00008-7