The mosquito Aedes aegypti is capable of transmitting a variety of pathogens to man and to other vertebrates. The midgut of this insect has been well-studied both as the tissue where the first contact occurs between ingested pathogens and the insect host, and as a model system for blood meal digestion in blood-sucking insects. To understand better the nature of the midgut surface encountered by parasites or viruses, we used scanning electron microscopy to identify the most prominent structures and cell morphologies on the luminal midgut surface. The luminal side of the midgut is a complex and layered set of structures. The microvilli that are found on most, but not all, cells are covered by a network of fine strands that we have termed the microvilli-associated network (MN). The MN strands are membranous, as shown by a membrane bilayer visible in cross sections of MN strands at high magnification in transmission electron micrographs. The MN is found in blood-fed as well as unfed mosquitoes and is not affected by chitinase treatment, suggesting that it is not related to the chitinous peritrophic membrane that is formed only after blood feeding. The cells in the midgut epithelium have two distinct morphologies: the predominant cell type is densely covered with microvilli, while cells with fewer microvilli are found interspersed throughout the midgut. We used lectins to probe for the presence of carbohydrates on the midgut surface. A large number of lectins bind to the luminal midgut surface, suggesting that a variety of sugar linkages are present on the structures visualized by electron microscopy. Some of these lectins partially block attachment of malaria ookinetes to the midgut surface in vitro. Thus, the mosquito midgut epithelium, like the lining of mammalian intestines, is complex, composed of a variety of cell types and extensively covered with surface carbohydrate that may play a role in pathogen attachment.
A tubular network associated with the brush-border surface of the Aedes aegypti midgut: implications for pathogen transmission by mosquitoes
H. Zieler, C.F. Garon, E.R. Fischer, M. Shahabuddin; A tubular network associated with the brush-border surface of the Aedes aegypti midgut: implications for pathogen transmission by mosquitoes. J Exp Biol 15 May 2000; 203 (10): 1599–1611. doi: https://doi.org/10.1242/jeb.203.10.1599
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The Forest of Biologists
We are excited to announce the launch of The Forest of Biologists, a new biodiversity initiative created with support from the Woodland Trust, aiming to counteract nature loss and safeguard some of the most critically endangered ecosystems for future generations. Do take a look around our virtual forest. For every Research Article and Review/Commentary article that is published in JEB, a native tree is planted in a forest in the UK.
Celebrating 100 years of discovery
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Looking back on the first issue of JEB
Journal of Experimental Biology launched in 1923 as The British Journal of Experimental Biology. As we celebrate our centenary, we look back at that first issue and the zoologists publishing their work in the new journal.
In our new Conversation series JEB@100, JEB Editor-in-Chief Craig Franklin talks about the big outstanding questions in the field of physiological plasticity and why he thinks a sense of community is key to the journal's success. Find out more here.
Deer mice overheat and struggle to run in high temperatures
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