Two-dimensional polyacrylamide gel electrophoresis of proteins synthesized and released by conceptuses and endometria from pony mares.

The research focused on identifying the variety of proteins synthesized and released by the conceptuses (embryos) and endometria (the lining tissues of the uterus) in pregnant pony mares. Samples were obtained at different stages of pregnancy from day 12 through day 100 and analyzed using two-dimensional polyacrylamide gel electrophoresis, a technique utilized to study proteins.

Methodology and Experimental Procedure

• The researchers obtained conceptuses from pony mares at each day of pregnancy between Days 12 and 28, further at Days 39, 45, 65 and 100. Endometrial tissues were also collected at Days 12, 14, 16, 18, 39, 45, 65 and 100 of pregnancy, and from non-pregnant mares during various reproductive stages.
• These tissues were then incubated in vitro for 24 hours with L-[3H]leucine, a common technique in biology to track protein synthesis.
• The proteins synthesized and those released into the culture medium were then analyzed using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and fluorography, an imaging technique, to gain information about their molecular structure and function.

Results

• The researchers identified that conceptuses obtained before Day 14 after ovulation released a specific pattern of labeled proteins. These proteins showed different molecular weight ranges and isoelectric points, an indicator of the pH at which the protein carries no net electrical charge.
• After Day 14, the array of synthesized proteins had changed and resembled the protein production pattern of the isolated yolk sac at later stages of pregnancy. Included amongst these were certain acidic polypeptides.
• The endometrial samples also released a variety of non-dialysable polypeptides into the culture medium. The research noticed that the endometrium from mares within the same pregnancy stage had similar patterns of protein synthesis.

The study provides valuable insight into the protein synthesis patterns of pregnant pony mares which could have implications in their reproductive biology. It also adds to the body of knowledge on horse breeding by providing information about the proteins synthesized at different stages of pregnancy.