“Comparative sequence analysis of canine progesterone receptor-B-Upstream Segment and the relationship of this segment with the estrous cycle in Canidae"
Summary
The dog seems to have unique features concerning activation function (AF) 3 domain and putative phosphorylation sites of the progesterone receptor-B-Upstream Segment (BUS) in comparison with mice, rats, rabbits, horses, cattle and human. The first aim of this research is to assess if the dog is still unique when compared to wolves, seals, ferrets, cats and pigs. A comparative sequence analyses was performed. In the wolf, the same differences as the dog were found in the AF3 domain and putative phosphorylation sites. Therefore, the differences found in AF3 domains and putative phosphorylation sites do not seem to be unique for the dog, but might be unique for wolf-like canids or Canidae in general.
According to many authors, canids or Canidae in general have a unique reproduction cycle. One of the remarkable features of this cycle is the prolonged luteal phase, during which progesterone is the dominating hormone. The question rises if there is a connection between the unique sequence of BUS and the apparently unique prolonged luteal phase of Canidae. Answering this question is the second aim of this study. Therefore, a short review was performed. Besides Canidae, also some members of the Ursidae and Phocidae families showed a prolonged luteal phase. These species were all monoestrous females with spontaneous ovulation. The sequence analysis of the seal showed no changes in the AF3 domain and the changes in the putative phosphorylation sites differed from the changes in the dog and wolf. Therefore, no connection between BUS and the estrous cycle could be assessed in Canidae.