The origin and functions of the insect peritrophic membrane and peritrophic gel

Abstract

There is a a fluid (peritrophic gel) or membranous (peritrophic membrane, PM) film surrounding the food bolus in most insects. The PM is composed of chitin and proteins, of which peritrophins are the most important. It is proposed here that, during evolution, midgut cells initially synthesized chitin and peritrophins derived from mucins by acquiring chitin-binding domains, thus permitting the formation of PM. Since PM compartmentalizes the midgut, new physiological roles were added to those of the ancestral mucus (protection against abrasion and microorganism invasion). These new roles are reviewed in the light of data on PM permeability and on enzyme compartmentalization, fluid fluxes, and ultrastructure of the midgut. The importance of the new roles in relation to those of protection is evaluated from data obtained with insects having disrupted PM. Finally, there is growing evidence suggesting that a peritrophic gel occurs when a highly permeable peritrophic structure is necessary or when chitin-binding molecules or chitinase are present in food.

The effect of sub-lethal doses of Azadirachta indica (Meliaceae) oil on the midgut of Spodoptera frugiperda (Lepidoptera, Noctuidae)

“…In the insect digestion systems there is a membrane composed of chitin, proteins (such as peritrophins) and proteoglycans, a peritrophic matrix layer that surrounds the food bolus with the function of offering chemical and mechanical protection as well as defense against pathogens (Terra 1996;Lehane 1997;Tellam et al 1999).…”

Alternative splicing of papilin and the diversity of Drosophila extracellular matrix during embryonic morphogenesis

“…We conclude that the cells of the recurrent middle wall secrete papilin into the lumen formed by the recurrent middle and outer proventricular walls and that this papilin becomes part of the peritrophic membrane that originates there. Peritrophic membranes, which function in the defense and digestion of insects, contain chitin and incompletely characterized glycoproteins, proteoglycans and the family of chitin-binding peritrophins (Terra, 2001). Papilin is the first defined basement membrane component reported as a constituent of peritrophic membranes.…”

“…The peritrophic membrane is a molecular network that separates the cellular gut wall from the luminal, intestinal contents. It is continuously produced, is excreted with the feces, and is believed to function in protecting the gut wall from enzymatic and parasitic microbial attack (for review, Terra, 2001). The embryonic proventriculus forms at the junction of the ectodermal foregut and the endodermal, anterior midgut.…”

Derris (Lonchocarpus) urucu (Leguminosae) Extract Modifies the Peritrophic Matrix Structure of Aedes aegypti (Diptera:Culicidae)

“…The peritrophic matrix (PM) is an acellular sheet that involves the food separating it from the midgut epithelium (Richards & Richards 1977, Peters 1992, Terra 1996. There are two fundamental types of PM defined by their site of synthesis.…”

“…The PM is present in most insects at least at some stage in their lifecycle. It has important roles in facilitating the digestive process in the gut, protecting insects from invasion by viruses, bacteria, protozoa and helminthes, and protecting midgut cells from abrasive food particles (Shahabuddin et al 1996, Tellam 1996, Lehane 1997, Terra 2001. A novel role for the PM is suggested.…”