title: Serum hormone levels associated with spawning activity in the mummichog, Fundulus heteroclitus.
abstract: Daily collections of the mummichog, Fundulus heteroclitus, from field populations during the first 45 days of the breeding season revealed a semilunar cycle in the sperm index. Peaks in the sperm index were preceded by 6 days with peaks in the serum testosterone concentration. Bihourly sampling of field populations during a 72-hr period at the new moon showed both diel cycling and an upward trend in serum progesterone levels in female mummichogs. Male mummichogs had 12-hr cycles in serum 17 beta-hydroxy-4-androstene-3,11-dione levels, the peaks of which preceded high tide by 4 hr. The physiological significance of these cycles are discussed.
authors.affiliation: Johns Hopkins University Chesapeake Bay Institute, Shady Side, Maryland 20764.
authors.forename: R C
authors.initials: RC
authors.lastname: Cochran
authors.forename: S D
authors.initials: SD
authors.lastname: Zabludoff
authors.forename: K T
authors.initials: KT
authors.lastname: Paynter
authors.forename: L
authors.initials: L
authors.lastname: DiMichele
authors.forename: R E
authors.initials: RE
authors.lastname: Palmer
mesh_terms: D000728:Androgens / Q000097:blood* / Q000494:pharmacology; D000818:Animals; D002940:Circadian Rhythm; D004967:Estrogens / Q000097:blood / Q000494:pharmacology; D005260:Female; D005306:Fertilization; D005399:Fishes / Q000097:blood*; D008297:Male; D009866:Oogenesis / Q000187:drug effects; D013091:Spermatogenesis / Q000187:drug effects
chemical_list: D000728:Androgens; D004967:Estrogens