Identification and initial characterization of calcyclin and phospholipaseA(2) in equine conceptuses

For development to proceed normally, the appropriate genes must be expresse d in the correct tissues and in the correct time frame. Knowledge of gene e xpression during development provides information about the changes taking place within the conceptus as well as possible reasons for pregnancy failur e. However, little is known about gene expression during development in the equine conceptus. In this study, we examined differences in gene expressio n between day 12 and day 15 equine conceptuses by suppression subtractive h ybridization. This technique was used to isolate transcripts that are more abundantly expressed in day 15 conceptuses compared to day 12 conceptuses. Between day 12 and 15 of pregnancy in horses, maternal recognition of pregn ancy occurs, gastrulation is taking place, and mesoderm is beginning to for m. Fifty cDNA clones were isolated, sequenced, and compared to known sequences in the GenBank database. Two cDNA clones identified that were of primary i nterest were calcyclin and phospholipase A(2). Calcyclin is a calcium-bindi ng protein of the S-100 protein family that has been found in mouse decidua and trophoblast. Calcyclin was found to be expressed in both day 12 and 15 equine conceptuses, with approximately a 30-fold increase in transcript ab undance between days 12 and 15. Phospholipase A2 is an enzyme that cleaves phospholipids to release fatty acids and is involved in arachidonic acid re lease needed for prostaglandin, thromboxane, and leukotriene synthesis. Mul tiple forms of PLA(2), that appear to be differentially regulated in day 12 and 15 conceptuses, were detected by northern blotting. Mol. Reprod. Dev. 53:179-187, 1999. (C) 1999 Wiley-Liss, Inc.