SREL Reprint #2338

 

 

 

Lipid analysis of Aglaodiaptomus stagnalis Forbes and their desiccation resistant diapause eggs

J. Williams-Howze, B.E. Taylor, P.M. Biesiot and G. Seaborn

 

Abstract: Aglaodiaptomus stagnalis Forbes is a prevalent member of temporary ponds throughout the southeastern United States. Females are large, bright red and produce orange diapausing eggs capable of complete desiccation for long periods. The early eggs are orange due to the lipid reserves; as the eggs develop, the embryos utilize the lipid and become dark brown. This study compared total lipid content and lipid classes of males, females, copepodites and eggs as well as the fatty acid profile of females with eggs and non-gravid females (those without egg sacs). Lipid reserves per individual occurred in the following order of decreasing weight: males, females, copepodites, eggs. The dominant lipid class in all stages is triacylglycerol (TAG), a common storage lipid often dominant in freshwater copepods. Overall, the n-3 fatty acid levels are higher among gravid females compared to non-gravid females, most notably the 18:3n-3 followed by 20:5n-3 and 22:6n-3. Gravid females also have a higher percentage of 18:2n-6. On the other hand, gravid females exhibit a lower percentage of saturated fatty acids as well as some polyunsaturated fatty acids (PUFA) including 20:4n-6 and 22:5n-6 compared to non-gravid females. Our data suggest that female A. stagnalis incorporate a large percentage of lipid as TAG in the egg sacs. This probably allows the diapause eggs to survive potentially long desiccation times, and to undergo rapid development when diapause is terminated. Although fatty acid profiles of the egg sacs themselves were not done, differences between the profiles of gravid and non-gravid females indicate that some fatty acids may be shunted non-selectively to the egg sacs whereas others may be preferentially sequestered in the egg sacs.

SREL Reprint #2338

Williams-Howze, J., B.E. Taylor, P.M. Biesiot, and G. Seaborn. 1998. Lipid analysis of Aglaodiaptomus stagnalis Forbes and their desiccation resistant diapause eggs. Arch. Hydrobiol. Spec. Issues Advanc. Limnol. 52:493-506.

 

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