Lipophorin from the tsetse fly, Glossina morsitans morsitans.

1. Lipophorin was isolated from the haemolymph of adult tsetse fly, Glossina morsitans morsitans, by ultracentrifugation in a potassium bromide density gradient. 2. The tsetse fly lipophorin (Mr congruent to 600,000) has a density of congruent to 1.11 g/ml and consists of two apoproteins, apolipophorin-I (apoLp-I, Mr congruent to 250,000) and apolipophorin-II (apoLp-II, Mr congruent to 80,000), both of which are glycosylated as shown by staining with periodate-Schiff reagent. The protein complex is composed of 49% protein and 51% lipids. 3. The finding of lipophorin in tsetse fly haemolymph suggests that, although these flies primarily utilize proline for their energy needs, there is an active transport mechanism for the supply of lipid requirements.     

Octopamine distribution in the tsetse fly Glossina morsitans

Tissues of Glossina morsitans were assayed for octopamine using an enzymatic technique. Octopamine was detected at the highest concentration in the brain (7.06-7.99 ng mg-1 tissue protein) and thoracic ganglion (10.9-13.89 ng mg-1 tissue protein). Octopamine was present in haemolymph at a concentration of 1.0-1.27 X 10(-7) M. This was not found to vary when insects were flown or mechanically stressed. Nervous tissue, flight muscle and haemolymph showed a significant ability to metabolize octopamine. The greatest enzyme activity was present in the haemolymph.     

Juvenile hormone mimics as effective sterilants for the tsetse fly Glossina morsitans morsitans

The development of puparia of Glossina morsitans morsitans Westwood was disrupted by topical applications of the juvenile hormone mimics S-methoprene (the resolved enantiomer of 11-methoxy-3,7,11-trimethyl-2,4-dodecadienoic acid 1-methyl ester) (Zoecon), S21149 (propionaldoxime-0-4-phenoxyphenoxyethylether) (Sumitomo), or S31183 (2-[1-methyl-2-(4-phenoxyphenoxy)ethoxy]pyridine) (Sumitomo) dissolved in acetone. Puparia so treated during the first 4 days of life suffered developmental abnormalities, the severity of which were dose-dependent. Similarly, puparia produced by adult females treated with these compounds were abnormal. Dose-response data showed that effects were greatest with S31183 and least with S-methoprene. Abnormalities in the form of abdominal lesions and wing crumpling were typical of flies emerging from puparia produced by S-methoprene-treated females. However, arrested development at the red eye and pigmented seta stage within the puparium were typical of offspring of females treated with S21149 and S31183. A dose of 2 micrograms per female of S31183 was sufficient to prevent emergence of offspring produced for the rest of the life of the fly. The same dose resulted in partial recovery of females treated with S21149 some 18 days following treatment. Treatment with 2 micrograms S-methoprene did not suppress completely the production of normal offspring and recovery was complete some 27-35 days after treatment. Exposure of males to 20 micrograms S31183 did not impair their ability to inseminate females; transfer of material during copulation was sufficient to prevent the production of viable offspring by their mates.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cloning and expression of the yolk protein of the tsetse fly Glossina morsitans morsitans

Two major families of nutritional proteins exist in insects, namely the vitellogenins and the yolk proteins. While in other insects only vitellogenins are found, cyclorraphan flies only contain yolk proteins. Possible sites of yolk protein synthesis are the fat body and the follicle cells surrounding the oocyte. We report the cloning of the yolk protein of the tsetse fly Glossina morsitans morsitans, a species with adenotrophic viviparity. The tsetse fly yolk protein could be aligned with other dipteran yolk proteins and with some vertebrate lipases. In contrast to the situation in most fly species, only a single yolk protein gene was found in the tsetse fly. Northern blot analysis showed that only the ovarian follicle cells, and not the fat body represents the site of yolk protein synthesis.     

The effect of exercise on the growth of mitochondria and myofibrils in the flight muscles of the tsetse fly,Glossina morsitans

Exercise affects the growth of the dorsal longitudinal flight muscles in the tsetse fly. Examination of electron micrographs of flight muscles taken from flies subjected to enforced exercise, “ormal” exercise and no exercise reveals that both mitochondrial and myofibrillar fractions of the muscles are stimulated to grow at a faster rate by enforced exercise but that the mitochondria respond more rapidly.     

A study on isoenzyme polymorphism in the tsetse fly Glossina morsitans

Polymorphism was studied for a number of enzyme systems in the tsetse fly Glossina morsitans. Enzyme polymorphism was observed for -glycerophospate dehydrogenase, aldehyde oxidase and esterases. For esterases, the operation of null alleles was assumed, as otherwise no explanation could be given for the observed frequencies of the variants.Two laboratory colonies and two field populations were compared with respect to their variation at the leucine aminopeptidase (Lap) loci, for which polymorphism was shown to occur in previous work. Conspicuous differences were found between material originating from Tanzania and from Rhodesia. In addition, allelic relationships were established for the Lap ₃-locus.

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Résumé Faisant suite à des études antérieures, le polymorphisme d'un certain nombre de systèmes enzymatiques a été étudié chez Glossina morsitans. Un polymorphisme a été observé pour l' -glycerophosphate déhydrogénase, pour l'aldéhyde-oxydase et pour les estérases. Pour les estérases, on a supposé l'intervention d'allèles nuls, les fréquences observées chez les variants ne pouvant être expliquées d'autre façon.Deux colonies élevées au laboratoire et deux populations naturelles ont été comparées quant à leur variation au niveau des loci (Lap) pour la leucine aminopeptidase, pour lesquels un travail antérieur avait mis en évidence un polymorphisme. Des différences nettes ont été trouvées entre le matériel provenant de Tanzanie et celui de Rhodésie. En outre des parentés alléliques ont été établies en ce qui concerne le locus Lap ₃.

     

Structural studies on the major milk gland protein of the tsetse fly, Glossina morsitans morsitans.

1. The major protein in the milk gland secretions of the tsetse fly, Glossina morsitans morsitans, was isolated by a combination of gel permeation chromatography and crystallization. 2. It has a native Mr approximately 47,000 and is composed of two identical polypeptide chains (Mr approximately 21,000) as determined by chemical cross-linking studies. The protein has no covalently-bound carbohydrates or lipids. Amino acid analysis of the protein revealed relatively high amounts of the aromatic amino acids, tyrosine (9.1 mol.%) and phenylalanine (8.5 mol.%). Immunoblotting experiments using antiserum against the protein revealed no cross-reactivity with any other milk proteins. 3. Quantitation of the protein during the pregnancy cycle showed that synthesis of the protein by the milk glands of adult female flies starts as the larva moults into second instar and rapidly declines as it matures into third instar. 4. It is proposed that the major milk gland protein could provide essential amino acids needed for the puparium formation.     

The effect of ambient temperature on the flight performance of the mature male tsetse fly, Glossina morsitans

ABSTRACT. The wingbeat frequency at flight initiation in mature male G.morsitans West, rose approximately linearly from 213 Hz at 20°C to 263 Hz at 32°C. An increase of temperature to 36°C produced no further effect. The time course of frequency changes was affected in a complex manner by temperature, due probably to the interaction of a number of physico-chemical and behavioural processes with different temperature dependencies. Higher temperatures caused a more rapid overall decline in wingbeat frequency, consistent with the greater demand on the limited reserve of the only important flight substrate, proline. At 20°C, a considerable proportion of tsetse were relatively inactive, whilst a small proportion flew for longer than at any other temperature. At intermediate temperatures both extremes in flight duration decreased, but at 36°C 80% of tsetse flew for less than 90s. These observations can be explained on the basis of the interaction between the tendency of tsetse to be inactive at extremes of temperature, and the more rapid oxidation of reserves at higher temperatures.     

The roles of vision and olfaction in mate location by males of the tsetse fly Glossina morsitans morsitans

The roles of visual and/or olfactory stimuli in eliciting mating responses from male Glossina morsitans morsitans Westwood were examined, using a system for automatically recording the number and duration of mating strikes made towards decoys, under controlled conditions. The results confirm that there is no olfactory component of the female sex recognition pheromone sensed by the male antennae, and the attraction of males to females appears to be visual. The absence of male-male mating strikes was the result of the absence of female sex-pheromone, rather than the presence of a repellent mating deterrent in the male cuticle. Experiments with coloured, artificial, sex-pheromone-dosed, cotton decoys showed that colour had only weak effects on attractiveness and number of encounters with decoys, and that no colour caused significant enhancement of mating responses over those shown to decoy females.     

Towards improving tsetse fly paratransgenesis: stable colonization of Glossina morsitans morsitans with genetically modified Sodalis

Background

Tsetse flies (Glossina sp.) refractory to trypanosome infection are currently being explored as potential tools to contribute in the control of human and animal African trypanosomiasis. One approach to disrupt trypanosome transmission by the tsetse fly vector involves the use of paratransgenesis, a technique that aims to reduce vector competence of disease vectors via genetic modification of their microbiota. An important prerequisite for developing paratransgenic tsetse flies is the stable repopulation of tsetse flies and their progeny with its genetically modified Sodalis symbiont without interfering with host fitness.

Results

In this study, we assessed by qPCR analysis the ability of a chromosomally GFP-tagged Sodalis (recSodalis) strain to efficiently colonize various tsetse tissues and its transmission to the next generation of offspring using different introduction approaches. When introduced in the adult stage of the fly via thoracic microinjection, recSodalis is maintained at high densities for at least 21 days. However, no vertical transmission to the offspring was observed. Oral administration of recSodalis did not lead to the colonization of either adult flies or their offspring. Finally, introduction of recSodalis via microinjection of third-instar larvae resulted in stably colonized adult tsetse flies. Moreover, the subsequent generations of offspring were also efficiently colonized with recSodalis. We show that proper colonization of the female reproductive tissues by recSodalis is an important determinant for vertical transmission.

Conclusions

Intralarval microinjection of recSodalis proves to be essential to achieve optimal colonization of flies with genetically modified Sodalis and its subsequent dissemination into the following generations of progeny. This study provides the proof-of-concept that Sodalis can be used to drive expression of exogenous transgenes in Glossina morsitans morsitans colonies representing a valuable contribution to the development of a paratransgenic tsetse fly based control strategy.

     

Development of mitochondrial and contractile components of the flight muscle in adult tsetse flies, Glossina morsitans

Estimates have been made of the phospholipid, the water, and the cytochrome-c content of the dorsal longitudinal flight muscles of the tsetse fly, and of the total non-fatty dry weight of the thorax, at different stages of adult development. The results have served as a basis for the partitioning of the dry weight of flight muscle into its three main components—contractile protein, mitochondrial protein, and phospholipid. Development is shown to involve a twofold increase in the amount of contractile protein, and a threefold increase in the amount of mitochondrial protein. These changes are discussed in relation to associated changes in wingbeat frequency.