Midgut

About: Midgut is a research topic. Over the lifetime, 3371 publications have been published within this topic receiving 90832 citations.

ENETS Consensus Guidelines for the management of patients with liver and other distant metastases from neuroendocrine neoplasms of foregut, midgut, hindgut, and unknown primary.

Abstract: ENETS Consensus Guidelines for the Management of Patients with Liver and Other Distant Metastases from Neuroendocrine Neoplasms of Foregut, Midgut, Hindgut, and Unknown Primary

Peritrophic matrix structure and function.

Abstract: Formed of proteins, glycoproteins, and chitin microfibrils in a proteoglycan matrix, the peritrophic matrix (PM) separates the food from the midgut epithelium in most but not all insects. A PM occurs in two forms. A type I PM is delaminated from the entire midgut epithelium and, in some cases, may only be formed in response to feeding and the type of meal ingested. A type II PM is produced by a specialized region of the anterior midgut called the cardia and forms a continuous sleeve (or sleeves) that is always present. As it is positioned between food and midgut epithelium, the PM plays key roles in the intestinal biology of the insect. The PM may protect the midgut epithelium from mechanical damage and insult from pathogens and toxins; it must act as a semipermeable membrane regulating passage of molecules between the different midgut compartments; and it may separate the midgut lumen into different, physiologically significant compartments.

Natural Microbe-Mediated Refractoriness to Plasmodium Infection in Anopheles gambiae

Abstract: Malaria parasite transmission depends on the successful transition of Plasmodium through discrete developmental stages in the lumen of the mosquito midgut. Like the human intestinal tract, the mosquito midgut contains a diverse microbial flora, which may compromise the ability of Plasmodium to establish infection. We have identified an Enterobacter bacterium isolated from wild mosquito populations in Zambia that renders the mosquito resistant to infection with the human malaria parasite Plasmodium falciparum by interfering with parasite development before invasion of the midgut epithelium. Phenotypic analyses showed that the anti-Plasmodium mechanism requires small populations of replicating bacteria and is mediated through a mosquito-independent interaction with the malaria parasite. We show that this anti-Plasmodium effect is largely caused by bacterial generation of reactive oxygen species.

Biology of the Insect Midgut

Abstract: List of contributors. Preface. Part One: Structural biology of the midgut. 1. Structure and ultrastructure of the insect midgut P.F. Billingsley, M.J. Lehane. 2. Midgut development K.M. Baldwin, et al. 3. Midgut endocrine cells F. Sehnal, D. Zitnan. 4. The peritrophic matrix R.L. Tellam. 5. Structural macromolecules of the cell membranes and the extracellular matrices of the insect midgut N.J. Lane, et al. Part Two: Digestion and transport. 6. Digestive enzymes W.R. Terra, et al. 7. Mechanisms controlling the synthesis and secretion of digestive enzymes in insects M.J. Lehane, et al. 8. Compartmentalization of digestion W.R. Terra, et al. 9. Ion transport in Lepidoptera U. Klein, et al. 10. Amino acid absorption V.F. Sacchi, M.G. Wolfersberger. 11. Lipid and sugar absorption S. Turunen, K. Crailsheim. Part Three: The midgut as a target for control strategies. 12. Immune intervention against blood-feeding insects P. Willadsen, P.F. Billingsley. 13. Bacillus thuringiensis endotoxins: action on the insect midgut P.V. Pietrantonio, S.S. Gill. 14. Antinutritive plant defence mechanisms G.W. Felton, J.A. Gatehouse. Part Four: The midgut as an environment for other organisms. 15. Microbialsymbioses in the midgut of insects A.E. Douglas, C.B. Beard. 16. Insect-transmitted pathogens in the insect midgut D.C. Kaslow, S. Welburn. Index.

Midgut bacteria required for Bacillus thuringiensis insecticidal activity

Abstract: Bacillus thuringiensis is the most widely applied biological insecticide and is used to manage insects that affect forestry and agriculture and transmit human and animal pathogens. This ubiquitous spore-forming bacterium kills insect larvae largely through the action of insecticidal crystal proteins and is commonly deployed as a direct bacterial spray. Moreover, plants engineered with the cry genes encoding the B. thuringiensis crystal proteins are the most widely cultivated transgenic crops. For decades, the mechanism of insect killing has been assumed to be toxin-mediated lysis of the gut epithelial cells, which leads to starvation, or B. thuringiensis septicemia. Here, we report that B. thuringiensis does not kill larvae of the gypsy moth in the absence of indigenous midgut bacteria. Elimination of the gut microbial community by oral administration of antibiotics abolished B. thuringiensis insecticidal activity, and reestablishment of an Enterobacter sp. that normally resides in the midgut microbial community restored B. thuringiensis-mediated killing. Escherichia coli engineered to produce the B. thuringiensis insecticidal toxin killed gypsy moth larvae irrespective of the presence of other bacteria in the midgut. However, when the engineered E. coli was heat-killed and then fed to the larvae, the larvae did not die in the absence of the indigenous midgut bacteria. E. coli and the Enterobacter sp. achieved high populations in hemolymph, in contrast to B. thuringiensis, which appeared to die in hemolymph. Our results demonstrate that B. thuringiensis-induced mortality depends on enteric bacteria.