Notes on the Process of Digestion in Tsetse-flies

Abstract

(1) The salivary glands of Glossina contain a powerful anticoagulin, which delays the clotting of blood of mammals, birds, reptiles and batrachians. It was found that when the salivary glands are removed from the living fly, it can still draw blood normally and may live long, but sooner or later large clots form in the narrow anterior portions of the alimentary tract, so that the fly can no longer feed and dies of starvation. The purpose of the anticoagulin is to prevent such clotting and blood coagulation in the crop.(2) The proventriculus and first third of the mesenteron are themselves inert in relation to coagulation of blood, but as removed from the normal fly they contain the anticoagulin which is derived from the salivary secretion.(3) The hinder part of the mesenteron contains a powerful coagulin, the purpose of which is to neutralise the anticoagulin and cause a rapid clotting, in order to retain the fluid meal in the proper region while draining and assimilation take place, probably also to save strain on the sphincter mesenteri and prevent the occasional loss of food through the anus.

A thrombin inhibitor from the gut of Boophilus microplus ticks

“…Presence of a diVerent thrombin inhibitor in gut reinforces the coagulation inhibition initiated by saliva, thus contributing to the success of blood feeding, which depends on keeping the sucked blood Xuid in the bite site, in the buccal apparatus and in the gut. This was Wrst observed by Lester and Lloyd (1926) in experiments with bloodsucking Xies, and was corroborated by Cappello et al (1998) who proved that the tsetse thrombin inhibitor, Wrst isolated from salivary glands of Xies, is also expressed in the midgut. In the case of B. microplus, however, the gut has an anticoagulant diVerent from the salivary ones (BmAP and microphilin).…”

Anterior midgut proteinase inhibitor from Glossina morsitans morsitans Westwood (Diptera: Glossinidae) and its effects upon tsetse digestive enzymes

“…To determine if proteinase inhibitor was the anticoagulant described from the anterior midgut (Lester and Lloyd 1928) simultaneous determinations of proteinase inhibitor, anticoagulant, and protein, as absorbance at 280nm, were carried out from a single fractionation of anterior midgut material using the small Sephadex G-75 column. Salivary gland homogenate was applied to the same column in a second run and assayed for anticoagulant activity.…”

Errata

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In "higher" flies (e.g. In our recent studies on the feeding of S. calcitrans, we noted that the change in the size of the abdominal air-sacs, besides making room for the growing abdominal organs, may minimize change in abdominal volume during feeding and digestion.Adult stable flies of both sexes feed on blood, and they usually take an amount of blood equal to I1/z-2 times their own weight (Kuzina 1942), as is found also in tsetse flies (Lester and Lloyd 1928). The main function of these air-sacs appears to be to maintain the extended external shape of the abdomen in newly emerged flies, because as the fat-bodies in both sexes, and also eggs in the female, grow, these air-sacs decrease in size, thus allowing room for these growing organs (Evans 1935).

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“…Adult stable flies of both sexes feed on blood, and they usually take an amount of blood equal to I1/z-2 times their own weight (Kuzina 1942), as is found also in tsetse flies (Lester and Lloyd 1928). In the laboratory, newly emerged stable flies usually have their wings still unexpanded and their abdomen shrunken, but 1 h thereafter, the wings and abdomen become fully extended.…”