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VARIATION IN GROWTH, LIPID CLASS AND FATTY ACID COMPOSITION OF THE MUD CRAB, RHITHROPANOPEUS HARRISII (GOULD) DURING LARVAL DEVELOPMENT FOLLOWING EXPOSURE TO AN INSECT JUVENILE HORMONE ANALOG (FENOXYCARB(R))
Citation:
Nates, S. F. AND C L. McKenney Jr. VARIATION IN GROWTH, LIPID CLASS AND FATTY ACID COMPOSITION OF THE MUD CRAB, RHITHROPANOPEUS HARRISII (GOULD) DURING LARVAL DEVELOPMENT FOLLOWING EXPOSURE TO AN INSECT JUVENILE HORMONE ANALOG (FENOXYCARB(R)). Presented at Atlantic Coast Contaminants Workshop, "Endocrine Disruptors in the Marine Environment: Impacts on Marine Wildlife and Human Health, The Jackson Laboratory, Bar Harbor, ME, 22-25 June 2000.
Description:
This study examines the effects of fenoxycarb?, an insect juvenile hormone (JH) analog, on larval growth, and lipid class and fatty acid composition in first crabs of the mud crab Rhithropanopeus harrisii reared through total larval development in nominal water concentrations from 1 to 100 ?g/l. Ovigerous females of R. hararisii were collected in shallow waters of Perdido Bay, FL, during 1999, and thereafter maintained individually until larvae hatched. Each exposure concentration and the control consisted of three replicate 10-cm bowls containing approximately 50 ml of test media. Ten larvae were added randomly to each bowl and maintained in an incubator at 25?1?C and a 12:12 h photoperiod. Upon completion of metamorphosis, living representatives of first crabs were collected and freeze-dried for further biochemical analysis. Lipids were extracted from samples after homogenization in chloroform/methanol (2:1 v/v) and lipid content was obtained gravimetrically. Lipid classes were determined by separating a portion of the total lipid extract on matched SII chromarods and quantified using an Iatroscan. Polar and neutral lipids were separated using the dichloroethane-chloroform-glacial acetic acid-isopropanol (92:8.0:0.1:0.03) system. Methyl esters of the fatty acids were prepared by transesterification with 0.2 M KOH in methanol for 1 h at 37?C. After extraction with hexane, the composition was analyzed with a gas-lipid chromatograph. Fatty acid methyl esters were identified by comparison to the retention time of authentic standards, and the identities were confirmed by capillary gas chromatography-mass spectrometry. In first crabs of R. harrisii, dry weight (?g) decreased significantly (p<0.05) from 228.8 ? 38.2 ?g (n=9) in the controls to 131.8 ? 10.1 ?g (n=4) in animals exposed throughout larval development to 100 ?g/l fenoxycarb. A significant (p<0.05) reduction was found between total lipid content in the controls and first crabs reared at concentrations greater