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At least 19 recordsLinked to original sources
PubMed2025

Spiroplasma endosymbiont reduction of host lipid synthesis and Stomoxyn-like peptide contribute to trypanosome resistance in the tsetse fly Glossina fuscipes.

Tsetse flies (Glossina spp.) vector African trypanosomes that cause devastating diseases in humans and domestic animals. Within the Glossina genus, species in the Palpalis subgroup exhibit greater resistance to trypanosome infections compared to those in the Morsitans subgroup. Varying microbiota composition and species-specific genetic traits can significantly influence the efficiency of parasite transmission. Notably, infections with the endosymbiotic bacterium Spiroplasma have been documented in several Palpalis subgroup species, including Glossina fuscipes fuscipes (Gff). While Spiroplasma infections in Gff are known to hinder trypanosome transmission, the underlying mechanisms remain unknown. To investigate Spiroplasma-mediated factors affecting Gff vector competence, we conducted high-throughput RNA sequencing of the gut tissue along with functional assays. Our findings reveal elevated oxidative stress in the gut environment in the presence of Spiroplasma, evidenced by increased expression of nitric oxide synthase, which catalyzes the production of trypanocidal nitric oxide. Additionally, we observed impaired lipid biosynthesis leading to a reduction of this important class of nutrients essential for parasite and host physiologies. In contrast, trypanosome infections in Gff's midgut significantly upregulated various immunity-related genes, including a small peptide, Stomoxyn-like, homologous to Stomoxyn first discovered in the stable fly, Stomoxys calcitrans. We observed that the Stomoxyn-like locus is exclusive to the genomes of Palpalis subgroup tsetse species. GffStomoxyn is constitutively expressed in the cardia (proventriculus) and synthetic GffStomoxyn exhibits potent activity against Escherichia coli and bloodstream form of Trypanosoma brucei parasites, while showing no effect against insect stage procyclic forms or tsetse's commensal endosymbiont Sodalis in vitro. Reducing GffStomoxyn levels significantly increased trypanosome infection prevalence, indicating its potential trypanocidal role in vivo. Collectively, our results suggest that the enhanced resistance to trypanosomes observed in Spiroplasma-infected Gff may be due to the reduced lipid availability necessary for parasite metabolic maintenance. Furthermore, GffStomoxyn could play a crucial role in the initial immune response(s) against mammalian parasites early in the infection process in the gut and prevent gut colonization. We discuss the molecular characteristics of GffStomoxyn, its spatial and temporal expression regulation and its microbicidal activity against Trypanosome parasites. Our findings reinforce the nutritional influences of microbiota on host physiology and host-pathogen dynamics.

Animals↗
PubMed1978

Cyclic AMP is a likely mediator of ovulation in the tsetse fly.

Ovulation in tsetse flies is normally induced by mating, but virgins can be stimulated to ovulate with an injection of dibutyryl cyclic AMP, cholera toxin (a cyclic AMP generator), or aminophylline (a phosphodiesterase inhibitor). Thus, elevation of cyclic AMP is a likely link in the events leading to ovulation.

Aminophylline↗
PubMed1975

The micro-organisms of tsetse flies.

Micro-organisms from tsetse fly mycetomes were maintained in culture, where they were more pleomorphic than in the mycetomes, but were in some cases very similar to those observed in ovaries by other authors. Agglutination tests on the cultured forms indicated in affinity to Rickettsia. They were sensitive to antibiotics introduced by feeding flies on hosts treated with Ampicillin; this reduced the longevity and fecundity of the tsetse flies and appeared to disturb normal digestion of bloodmeals.

Agglutination Tests↗
PubMed1979

[Effect of bacterial infections and antibiotics on tsetse flies (Diptera, Glossinidae) (author's transl)].

The membrane feeding technique (in vitro feeding) used for the rearing of tsetse flies has advantages over the conventional method of feeding the flies on host animals. However, as long as blood remains the sole source of tsetse fly nutrition, the risk remains of blood being contaminated during collection, storage or feeding with bacteria pathogenic to the flies. The resulting high mortality of the tsetse flies endangers the success of this rearing. The experiments described here have shown that Glossina m. morsitans Westw. are more sensitive to Pseudomonas aeruginosa than G. p. palpalis Rob.-Desv. Rearing experiments over several years have confirmed this finding in that the latter species has never been threatened by high bacterial-induced mortality, whereas in 1973-74, due to contamination of the in vitro fed blood, a population of G. m. morsitans was difficult to colonize. The quantity of infected blood intake (14 to 70 mg) had no influence on the survival rate. However, when flies were infected once with Pseudomonas aeruginosa (dilution stage of 10(-3)), the organisms were eliminated after only nine days in living G. p. palpalis, but after 14 days in living G. m. morsitans. Females were infected at different stages of pregnancy but the same bacteria were not isolated in any puparia. Therefore, transmission of the bacteria to larvae growing in the uterus could not be demonstrated. All antibiotics used, to which bacteria isolated from tsetse flies in the laboratory were sensitive, caused a reduction in productivity. Parental females as well as females which emerged from larvae deposited by these flies (= F1-generation) 6 days after the administration of the drug to the pregnant females showed a similar loss in productivity. This corresponds with a degeneration of mesenteric symbionts. The most successful way to cope with bacterial infection in the membrane feeding technique in the rearing of tsetse flies has proved to be prophylactic measures, i.e. sterile membranes, sterile underlying aluminium trays and sterile blood. The methods employed at this laboratory, where up to 20 000 flies are being fed daily through membranes, have prevented dangerous bacterial infections in both species.

Animals↗
PubMed1977

Lethal effect of tetracycline on tsetse flies following damage to bacterioid symbionts.

High mortality was observed in tsetse flies, Glossina morsitans morsitans, that had had a single blood meal on rabbits which had previously been administered tetracycline complex salts. The death of the flies was apparently effected by the killing of the fly symbionts and the destruction of the mycetomes of the gut. It is suggested that tetracycline complex salts in the food or drink of livestock may be tried for the control of tsetse flies.

Animals↗
PubMed1975

Salivary secretion in three species of tsetse flies (Glossinidae).

The study of the mechanism and process of salivation in tsetse flies is of paramount importance towards a fuller understanding of the transmission of trypanosomiasis and nagana diseases. Gordon, Crewe and Willett (1956) made direct observations, through a microscope, of the haustellum of G. morsitans as it penetrated into the ear of an anesthetised mouse and found that probing was accompanied by a copious but intermittent ejection of saliva from the hypopharynx. The outpouring of the saliva commenced during penetration of the stratum corneum and was maintained throughout probing of the tissues. During engorgement, blood is taken in through the labium while saliva was discharged from the hypopharynx at the same time. Besides this work, very little else seems to have been done on the salivary secretion by tsetse flies especially in relation to the hunger cycle of the fly and to the species of tsetse. These aspects were studied on three important species of tsetse and are reported upon in this paper.

Animals↗
PubMed1979

Serratia marcescens as a pathogen of tsetse flies.

When applied to the ears of rabbits used as hosts for tsetse flies, the bacterium Serratia marcescens produced significant mortality in populations of Glossina m. morsitans and G. pallidipes. After being ingested during the blood meal, cells of S. Marcescens multiplied in the intestine of the flies and entered the hemocoel. Using the brush method of applying the bacterium, 100% mortality of both Glossina species occurred within 10 days after application. In newly killed flies, the bacteria could be found free in the hemocoel as well as in the fat body and blood cells. The supernatant of a liquid culture of S. marcescens did not produce fly mortality when applied to rabbit ears. The results indicate that S. marcescens is able to invade the hemocoel of "normal" laboratory-reared tsetse flies.

Animals↗
PubMed1979

Cyclical transmission of Trypanosoma brucei rhodesiense and Trypanosoma congolense by tsetse flies infected with culture-form procyclic trypanosomes.

Culture procyclic forms of Trypanosoma brucei rhodesiense and Trypanosoma congolense were fed to Glossina morsitans morsitans through artificial membranes. A very high percentage of the flies so fed produced established midgut infections, a proportion of which went on to develop into mature metacyclic trypanosomes capable of infecting mammalian hosts. The method offers a safe, clean way of infecting tsetse flies with African trypanosomes which reduces the need for trypanosome-infected animals in the laboratory.

Animals↗
PubMed1976

Physiology of an ATP receptor in labellar sensilla of the tsetse fly Glossina morsitans morsitans Westw. (Diptera: Glossinidae).

Electrophysiological recordings have been made from cells in the eight large, labellar sensilla of g. morsitans. One of these cells in each sensillum was shown to respond to ATP over a concentration range of 10(-6)-10(-3) M. It was also sensitive to several other adenosine phophates, but much less sensitive to CTP, GTP and ITP. The activity of the receptor was depressed below pH 7, and sometimes considerably increased above pH 9. These aspects the receptor's physiology support the results of behavioural studies. It is concluded that the eight receptors mediate the flies' behavioural response to ATP.

Action Potentials↗
PubMed1979

The feeding habits and ecology of the tsetse fly Glossina morsitans submorsitans Newstead in relation to nagana transmission in the Gambia.

The source of blood meals from 174 fed Glossina morsitans submorsitans Newstead, captured in malaise traps in Savanna woodland in The Gambia, were identified by the precipitin test. Warthog accounted for 90% of the meals and single bushbuck and ox feeds were identified. Nagana is a major problem in the area, but contact between tsetse and livestock is reduced by restricted grazing. In this situation, warthog, with a ubiquitous distribution, appear to be major maintenance hosts for G. m. submorsitans as well as a potential reservoir of trypanosomiasis.

Animals↗
PubMed1976

Active transport of sodium by the malpighian tubules of the tsetse fly Glossian morsitans.

Isolated Malpighian tubules of Glossina morsitans are able to transport sodium against its concentration gradient. Their rate of secretion is dependent on the sodium concentration of the bathing medium. Potassium must be present in the bathing solution for rapid secretion to be maintained, but it does not play an active role in fluid secretion. Lithium and ammonium ions are able to substitute partially for sodium, other monovalent cations cannot. Ouabain does not affect rapid secretion by Glossina tubules in vitro. Conclusions drawn from the results are incorporated into a model of Malpighian tubule cell function in this insect.

Animals↗
PubMed1979

Infectivity of Trypanosoma brucei cultivated at 28 C with tsetse fly salivary glands.

When transformed procyclic noninfective trypanosomes of several unrelated stocks of Trypanosoma brucei were cultivated in T-30 Falcon flasks at 28 C in a liquid medium containing head-salivary gland explants of Glossina morsitans morsitans some of the organisms developed into forms infective for mice. Infective trypanosomes were detected 7 to 14 days after the cultures were prepared and they persisted for varying periods of up to 88 days when the cultures were terminated. A few of the salivary glands became invaded with parasites about the time infective organisms appeared in the cultures. Using T. brucei TREU 929, it was shown that trypanosomes grown with between 2m and 50 explants were capable of producing infections consistently for prolonged periods. On the other hand, trypanosomes cultivated with 25 or fewer explants rarely infected mice. Infectivity titrations on trypanosome suspensions from cultures of stocks TREU 1275 and TREU 929 revealed that the maximum number of infective organisms was present 26 to 50 days after initiation of the cultures. Control cultures of trypanosomes grown in medium alone were generally not infective but 2 of the 6 stocks gave rise to a few sporadic infections. A few epimastigote-like and metacyclic-like trypanosomes were seen in stained preparations of infective inocula.

Animals↗