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Photoperiodic Regulation of Gametogenesis in Sea Stars, with Evidence for an Annual Calendar Independent of Fixed Daylength1'1
BibTeX
@MISC{Pearse_photoperiodicregulation,
author = {John S. Pearse and Douglas J. Eernisse and Vicki B. Pearse and Katherine and A. Beauchamp},
title = {Photoperiodic Regulation of Gametogenesis in Sea Stars, with Evidence for an Annual Calendar Independent of Fixed Daylength1'1},
year = {}
}
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Abstract
SYNOPSIS. Gametogenesis and gonadal growth in the west coast sea star Pisaster ochraceus normally begins in the fall and leads to large gonads full of gametes in the spring, when spawning occurs. The timing of gametogenesis can be shifted simply by maintaining the animals on a seasonally changing photoperiodic regime out of phase with ambient. When they are kept on a spring-summer photoperiodic regime during the fall and winter, game-togenesis proceeds 6 mo ahead of schedule in the following spring and summer. Game-togenesis can be shifted out of phase even when the eyespots are removed. Short daylengths that normally occur during the fall and winter are not required for gametogenesis to proceed, nor are even the long daylengths of spring and summer that precede the initiation of gametogenesis in the fall. The temporal program is insensitive to fixed daylengths (LD 15:9, 13:11, 12:12, 9:15) and appears to involve an endogenous calendar. Shifting the photoperiodic regime 6 mo out of phase also leads to a shift of the game-togenic temporal program in the sea stars Leptasterias sp. (a brooder) and Asterias vulgaris (from the New England coast), but not in the sea star Patiria miniata. Gametogenic timing also can be switched in the sea urchin Strongylocentrotus purpuratus but the mechanism of the photoperiodic response is fundamentally different; gametogenesis requires short day-lengths; continues indefinitely under a repeated short day, fall-winter photoperiod regime, and apparently does not involve an endogenous calendar. As photoperiodic responses are investigated further in these and other marine invertebrates, the models developed pri-marily from studies on terrestrial organisms may need to be extensively modified or additional new models required.
Keyphrases
annual calendar independent photoperiodic regulation fixed daylength1 sea star photoperiodic response endogenous calendar photoperiodic regime short day-lengths gonadal growth following spring game-togenic temporal program repeated short day new england coast spring-summer photoperiodic regime temporal program short daylengths large gonad marine invertebrate asterias vulgaris sea star patiria miniata sea urchin strongylocentrotus purpuratus terrestrial organism game-togenesis proceeds fall-winter photoperiod regime long daylengths additional new model leptasterias sp gametogenic timing
