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Reprod. Nutr. Dev.
Volume 45, Number 2, March-April 2005
Page(s) 151 - 162
Reprod. Nutr. Dev. 45 (2005) 151-162
DOI: 10.1051/rnd:2005012

Relationship between MT1 melatonin receptor gene polymorphism and seasonal physiological responses in Île-de-France ewes

Xochitl Hernandeza, b, Loys Bodinc, Didier Chesneaua, Daniel Guillaumea, Philippe Chemineaua, Benoît Malpauxa and Martine Migauda

a  UMR INRA-CNRS-Université de Tours, Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France
b  Facultad de Medicina Veterinaria y Zootecnia, Departamento de Reproducción Animal, Universidad Nacional Autonoma de Mexico, Mexico
c  Station d'Amélioration génétique des animaux, Chemin de Borde-Rouge, Auzeville BP 27, 31326 Castanet-Tolosan Cedex, France

(Received 11 November 2004; accepted 14 December 2004)

Abstract - The gene encoding the MT1 melatonin receptor in sheep has a restriction fragment length polymorphism (RFLP) site to the MnlI enzyme whose incidence is associated to the expression of seasonality in several breeds. The aim of this study was to examine the relationship between this genetic marker and the physiological effects of MT1 receptor gene polymorphism on several seasonal functions in Île-de-France ewes. The study was performed using 12 pairs of half-sib adult Île-de-France ewes. Within each pair, ewes were selected on the basis of their genotype at the MnlI RFLP site: group +/+ and -/- (presence and absence of MnlI restriction site, respectively). No difference in the dates of the beginning, the end or the length of the breeding season was observed between groups during the two-year study. The seasonal changes in prolactin secretion were not different between groups. Similarly, wool growth rate and primary follicle activity, measured for one year, varied with the time of the year in the same way in the two groups. Our study therefore failed to show any relationship between MT1 polymorphism and reproductive seasonality in Île-de-France ewes. This suggests that the influence of this polymorphism on the regulation of seasonal function is dependent upon the breed and/or environmental conditions. The MT1 polymorphism can explain only a small part of the genetic variability of seasonal functions and the implication of other genes must be investigated.

Key words: polymorphism / MT1 receptor gene / reproduction / seasonal functions / genetic control / Île-de-France ewes

Corresponding author: Martine Migaud

© INRA, EDP Sciences 2005