Daily variations in crustacean hyperglycaemic hormone and serotonin immunoreactivity during the development of crayfish.
The present study investigated changes in crustacean hyperglycaemic hormone (CHH) and serotonin (5-hydroxytryptamine, 5-HT) immunoreactivity in the retina and the X-organ/sinus gland complex (XO-SG) of the crayfish Procambarus clarkii at two developmental stages, post-embryonic stage two (PO2) and the juvenile stage, at three different times of day, under a photoperiod cycle of 12 h:12 h L:D, using qualitative and quantitative immunohistochemical methods. In the retina, CHH immunoreactivity is located in the tapetal cells, while 5-HT immunoreactivity is found in the retinular cells. In the XO-SG, CHH-immunoreactivity is localized to the CHH-producing cell perikarya and in their axons and endings in the sinus gland, while 5-HT immunoreactivity is restricted to axon endings branching into the perikarya of the CHH-producing cells. A stereological analysis demonstrates that the PO2 and juvenile stages show significant differences in the amount of the immunoreactive CHH and 5-HT material at the three selected time points, indicating daily and related changes in the levels of CHH and 5-HT in the XO-SG and the retina. Our findings therefore support the idea that daily rhythms in the secretory activity of the XO-SG complex affect the circadian sensitivity of the eye. Furthermore, the differences found between the PO2 and juvenile stages suggest that both CHH and 5-HT are key factors in the development of the circadian rhythm of retinal sensitivity.
Escamilla-Chimal
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EG
Laboratorio de Neurofisiología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ap. Postal 41-630, CP 11000 México DF, México.
Van Herp
F
F
Fanjul-Moles
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ML
D000818:Animals; D060829:Arthropod Proteins; D003400:Astacoidea / Q000254:growth & development* / Q000378:metabolism; D002940:Circadian Rhythm; D007447:Invertebrate Hormones; D018613:Microscopy, Confocal; D009419:Nerve Tissue Proteins / Q000032:analysis*; D017440:Photoperiod; D012160:Retina / Q000737:chemistry; D012701:Serotonin / Q000032:analysis*
D060829:Arthropod Proteins; D007447:Invertebrate Hormones; D009419:Nerve Tissue Proteins; C015947:hyperglycemic hormone, crustacean; D012701:Serotonin