Invertebrate gut diverticula are nutrient absorptive organs

Area of Science:

• Comparative physiology
• Invertebrate biology
• Gastrointestinal physiology

Background:

• Gastrointestinal absorption and secretion mechanisms in invertebrates are poorly understood.
• Solute transfer across epithelial cells and membranes is influenced by physical and biological forces.

Purpose of the Study:

• To review the physiological mechanisms of gastrointestinal absorption and secretion of organic and inorganic solutes in invertebrates.
• To discuss solute transfer across epithelial cells and membranes in vertebrate and invertebrate guts.
• To present features of sugar and amino acid transport in echinoderms, molluscs, and arthropods.

Main Methods:

• Discussion of physical and biological forces affecting solute transfer.
• Presentation of sugar and amino acid transport features in invertebrate gastrointestinal tracts.
• Detailed analysis of nutrient transport studies using purified epithelial brush-border membrane vesicles.
• Transepithelial nutrient and ion transport studies using cultured crustacean hepatopancreatic epithelial cell monolayers.

Main Results:

• Epithelial cells and membranes play a crucial role in solute transfer.
• Specific features of sugar and amino acid transport were identified in echinoderms, molluscs, and arthropods.
• Studies using membrane vesicles and cell monolayers provided insights into nutrient and ion transport.
• The methods used are applicable to complex invertebrate organs.

Conclusions:

• Understanding invertebrate gastrointestinal physiology is crucial.
• Specific transport mechanisms for nutrients and ions exist in invertebrates.
• Advanced techniques like membrane vesicle and cell culture studies are valuable for investigating invertebrate gut function.
• These methods can be broadly applied to diverse invertebrate organ systems.