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EDRI Federal Project Inventory:
Photoperiodic Regulation of a Circannual Rhythm
- Sponsor Organization: NATIONAL SCIENCE FOUNDATION
- Project Title: PHOTOPERIODIC REGULATION OF A CIRCANNUAL RHYTHM
- Project Focus: ECOLOGICAL EFFECTS
- Description: Virtually all animals undergo marked changes in body structure,
function andbehavior which enable them to adapt to, and survive, the
hardships of a seasonallychanging natural environment. The goal of
Dr. Karsch's research is to understand themeans by which the changing
seasons regulate seasonal reproduction, a naturalprocess of reversible
fertility and infertility. He has selected domestic female sheep
asthe model system. In this species, the process of seasonal
reproduction is generatedspontaneously by a self-sustained endogenous
rhythm of neuroendocrine activity. Changes in day length provide time
cues which permit appropriate phasing of thisendogenous rhythm with
cyclic changes in the environment. Dr. Karsch will determinewhether a
short day photoperiodic cue is effective when given during anestrus,
andwhether a long day photoperiodic cue is ineffective when given
during the breedingseason. The specific photoperiodic messages will
be restored by infusion of melatonininto pinelectomized sheep.
Melatonin is a hormone secreted by the pineal gland only atnight, and
it enables the animal to tell how long the night is and thus the
duration of theday. The outcome of this research should lead to new
insights into a fundamentalproblem of enormous biological significance
and practical importance: the regulation offertility. The results
will also be more broadly applicable to a wide variety
ofphysiological, metabolic and behavioral rhythms which form an
integral part of theadaptive mechanisms in many animals. An
understanding of these processes shouldhave profound implications to
the reproductive biology of endangered species that areseasonal
breeding. Since the studies will be done in domestic sheep, the
findings willhave a direct bearing on production in the food and fiber
industries.
- References:
- Category: MODELS
- Subcategory: BASIC RESEARCH
- Keywords for Experimental System/Species: OVINE, MAMMAL, IN VIVO, LABORATORY STUDY
- Keywords for Experimental Endpoints: NEUROLOGICAL, REPRODUCTIVE, HORMONE MEASURES, SEX STEROIDS, PEPTIDE
HORMONES,PHYSIOLOGY, BREEDING BEHAVIOR, GROWTH, PHOTOPERIOD
- Chemical Agents: Sex Steroids, Peptide Hormones
- Performing Institution: University of Michigan
- Contact: Fred J Karsch, 3003 S. State St., Room 1026,Ann Arbor, MI 48109-1274
313 764-1817
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