Investigating proteins and proteases composing amniotic and allantoic fluids during chicken embryonic development

Area of Science:

• Comparative Physiology
• Developmental Biology
• Avian Embryology

Background:

• Amniotic fluid is vital for mammalian fetal development, but avian extraembryonic fluids remain understudied.
• Understanding chicken amniotic fluid (AmF) and allantoic fluid (AlF) composition and function is crucial for avian embryology.

Purpose of the Study:

• To characterize the properties, protein composition, and functions of chicken AmF and AlF from day 8 to day 16 of incubation.
• To investigate the distinct roles of these fluids in embryonic development.

Main Methods:

• SDS-PAGE and mass spectrometry were used to analyze protein profiles of AmF and AlF.
• Gelatin zymography and mass spectrometry identified active proteolytic enzymes.
• Physicochemical properties like osmolality and pH were measured.

Main Results:

• AmF and AlF exhibit distinct protein compositions, with AlF containing yolk proteins and AmF resembling albumen.
• Significant changes in AmF protein profiles occur during incubation, unlike AlF.
• AlF shows decreasing osmolality and pH, while AmF pH remains stable. Both fluids contain active proteases involved in digestion, morphogenesis, and hemostasis.

Conclusions:

• Chicken AmF and AlF possess unique protein compositions and dynamic changes, indicating specialized functions.
• These fluids contribute to embryonic development through metabolic regulation, protection, and potentially more complex roles in morphogenesis and hemostasis.
• The findings highlight the sophisticated roles of avian extraembryonic fluids beyond waste management.