Evolutionary studies on pancreatic colipase

Area of Science:

• Biochemistry
• Evolutionary Biology
• Comparative Physiology

Background:

• Bile salts inhibit pancreatic lipase activity, crucial for fat digestion.
• Colipase is known to restore lipase activity in mammals.
• The evolutionary history and presence of colipase in non-mammalian vertebrates remain largely unexplored.

Purpose of the Study:

• To investigate the evolutionary origins of colipase.
• To determine the presence and characteristics of colipase in various vertebrate species.
• To understand the co-evolution of colipase with bile salts and the exocrine pancreatic gland.

Main Methods:

• Characterization of colipase based on its ability to restore bile salt-inhibited lipase activity.
• Immunological cross-reactivity assays using antisera against mammalian colipases.
• Gel-filtration to estimate molecular weight.
• Detection of colipase activity in tissue extracts from hagfish, ratfish, rayfish, sharks, and crayfish.

Main Results:

• Colipase was identified as a heat-stable, low-molecular-weight protein (approx. 10,000 Da).
• Colipase activity was confirmed in the exocrine pancreatic cells of hagfish, ratfish, rayfish, Greenland shark, and dogfish.
• No colipase activity was detected in the gastric juice of crayfish.

Conclusions:

• Colipase evolved in vertebrates prior to the development of the organized exocrine pancreatic gland.
• The presence of colipase appears to coincide with the emergence of bile salts or bile alcohols.
• This study provides evidence for the ancient evolutionary role of colipase in lipid digestion across vertebrates.