Proteomic analysis of amniotic and allantoic fluid from buffaloes during foetal development

The objective of this study was to describe the dynamic changes in protein composition and protein abundance in amniotic and allantoic fluids from buffaloes during gestation. Amniotic and allantoic fluids were collected during the first, second and third trimesters of gestation. The foetuses were measured and weighed. Fluid samples were centrifuged at 800 g for 10 min and then at 10,000 g for 60 min at 4°C. The supernatant was collected to determine the total protein concentration. Based on total protein concentration, an aliquot (50 μg) was used for in-solution tryptic digestion, and mass spectrometry analysis (nano-LC-MS/MS) was performed. A multivariate statistical analysis of the proteomic data was conducted. Across the different stages of buffalo gestation, fifty-one proteins were found in the amniotic fluid, and twenty-one were found in the allantoic fluid. A total of twelve proteins were common among the stages, and four presented significant differences (VIP score α > 1). Fibronectin and alpha-1-antiproteinase were more abundant in the amniotic fluid than in the allantoic fluid. Alpha-2-macroglobulin and alpha-2-HS-glycoprotein were more abundant in the allantoic fluid than in the amniotic fluid. Alpha-2-macroglobulin participates in remodelling and growth of the uterus at beginning of the gestation (first trimester), and these findings indicate that can serve as a potential tool for the early diagnosis of pregnancy in buffaloes.