A.B. Bolten
K.A. Bjorndal
L. J. Guillette
T. S. Gross
D.A. Crain
1995
<p><span>This study examines size-dependent, sex-dependent, and seasonal fluctuations in plasma insulin-like growth factor-I (IGF-I) concentrations in loggerhead sea turtles (</span><i>Caretta caretta</i><span>). Loggerhead turtles (</span><i>n</i><span> = 158) were captured in shrimp trawler nets during a 12-month survey in Cape Canaveral Channel, Florida. Plasma samples were analyzed using a validated heterologous radioimmunoassay. Large turtles (>75 cm straight-line carapace length) had significantly higher plasma IGF-I concentrations than small turtles (⩽75 cm; </span><i>P</i><span> < 0.0001). Plasma IGF-I concentrations did not vary seasonally in small turtles, but large turtles had significantly higher plasma IGF-I concentrations during the spring and summer months (P < 0.005). Within the large turtles, adult males had significantly lower IGF-I concentrations than females and subadult males (</span><i>P</i><span> < 0.05). These results and a review of loggerhead turtle natural history suggest that the seasonal fluctuations in plasma IGF-I of adult turtles are due to elevated IGF-I levels in reproductively active female turtles. Further research is needed to examine correlations between reproductive activities and plasma IGF-I concentrations in reptiles.</span></p>
application/pdf
10.1006/gcen.1995.1063
en
Elsevier
Size-dependent, sex-dependent and seasonal changes in insulin-lige growth-factor-I in the loggerhead sea turtle
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