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Title: THE PRESENCE OF AN INTERCALATED DISK-LIKE STRUCTURE IN THE HINDGUT MUSCLES OF THE COCKROACH

Author
item Cook, Benjamin
item Pryor, Nan

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Recent research has shown that insect hormones known as neuropeptides regulate many critical life processes in insects and as such they offer considerable potential for the development of new and more effective methods of pest insect control. Neuropeptides are composed of short chains of amino acids, the building blocks of proteins. In earlier studies, we discovered a group of neuropeptides in the head of the cockroach that stimulate the contraction of certain muscles of that insect. This report identifies and describes a previously unknown structure between muscle cells located in the digestive tract of the cockroach. If neuropeptide research is ultimately to be successful in developing new and better methods of controlling pest insects, it is very important to know how these chemicals interact with the living systems they effect. The discovery of these new structures in insect muscle cells is important in understanding how insect muscles function.

Technical Abstract: An interfibrillar junction with many ultrastructural features of an intercalated disk was found in the circular muscle of the anterior rectum of the cockroach, Leucophaea maderae (Fabricius). This junction consisted of a central region with a large amount of electron-dense material associated with the I band of the myofibrils. A zona occludens was present in the plasma membrane that extended from the region of the myofilaments to the periphery of the cells. Intercalated disks have been frequently reported in insect cardiac muscle but this is the first recorded instance of its presence in insect non-cardiac muscle. Such interdigitated junctions appear to provide a means of adhesion between individual cells to prevent any separation during contraction. Moreover, gap junctions in the plasma membrane may provide an avenue for intercellular communication by ion exchange. Finally, the frequent and uniform rhythmic contractions of the muscles in the rectal valve suggest a heart-like action.