The adaptive significance of crustacean hyperglycaemic hormone (CHH) in daily and seasonal migratory activities of the Christmas Island red crab Gecarcoidea natalis.
The Christmas Island red crab Gecarcoidea natalis undergoes extreme changes in metabolic status, ranging from inactivity during the dry season, to a spectacular annual breeding migration at the start of the wet season. The dramatic change in metabolic physiology that this polarisation entails should be reflected in changes in endocrine physiology, particularly that of the crustacean hyperglycaemic hormone (CHH), of which we know relatively little. CHH levels were measured using a novel ultrasensitive time-resolved fluoroimmunoassay (TR-FIA), together with metabolites (glucose, lactate), in the field at several scales of temporal resolution, during migratory activities (wet season) and during the inactive fossorial phase (dry season). Release patterns of CHH were measured during extreme (forced) exercise, showing for the first time an unexpectedly rapid pulsatile release of this hormone. A seasonally dependent glucose-sensitive negative-feedback loop was identified that might be important in energy mobilisation during migration. Haemolymph lactate levels were strongly correlated with CHH levels in both field and experimental animals. During migration, CHH levels were lower than during the dry season and, during migration, daytime CHH levels (when most locomotor activity occurred) increased. However, the intense dawn activity in both dry and wet seasons was not always associated with repeatable hyperglycaemia or CHH release. The results obtained are discussed in relation to the life history and behaviour of G. natalis.
Morris
Stephen
S
School of Biological Sciences, University of Bristol, Woodland Road, Clifton, Bristol BS8 1UG, UK.
Postel
Ute
U
Mrinalini
Turner
Lucy M
LM
Palmer
Jessica
J
Webster
Simon G
SG
D000222:Adaptation, Physiological; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D060829:Arthropod Proteins; D001786:Blood Glucose / Q000378:metabolism; D003386:Brachyura / Q000502:physiology*; D025461:Feedback, Physiological; D015200:Fluoroimmunoassay; D006003:Glycogen / Q000378:metabolism; D006458:Hemolymph / Q000378:metabolism; D007447:Invertebrate Hormones; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008849:Micronesia; D009132:Muscles / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000097:blood / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D012015:Reference Standards; D012621:Seasons
D060829:Arthropod Proteins; D001786:Blood Glucose; D007447:Invertebrate Hormones; D009419:Nerve Tissue Proteins; C015947:hyperglycemic hormone, crustacean; D019344:Lactic Acid; D006003:Glycogen