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.     

Rhythmic pulses of haemolymph pressure associated with parturition and ovulation in the tsetse fly,Glossina morsitans

Abstract Expulsion of the tsetse larva from the uterus of the female is preceded by 1–2 h of rhythmic pulses of haemolymph pressure that can be detected using a barographic technique. At first baseline pressure is maintained and all pulses are positive in relation to baseline. Then, about 1 h before parturition, baseline pressure increases, pulse intensity increases, and the pulses become both positive and negative in relation to baseline. Each pulse correlates with ‘bobbing’ action of the female's proboscis, the only external indication of this internal activity. A single large pressure pulse is observed at parturition, and thereafter the pressure level returns to the original baseline and pulsing action ceases. Around the presumptive time of ovulation, 1–2 h after parturition, another series of pressure pulses is observed. The pulses are the likely consequence of coordinated waves of muscular contraction that are essential preparation for successful parturition and ovulation.     

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.     

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)     

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.

     

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.     

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.     

Neuroendocrine stimulation of uterine gland protein synthesis in the tsetse fly, Glossina morsitans

ABSTRACT. The uterine gland of the tsetse fly Glossina morsitans morsitans Westw. synthesizes a secretion which nourishes the developing larva in the uterus. Aqueous extracts of the brain have been shown to stimulate the synthesis of the protein and amino acid components of this secretion from L- [U-¹⁴C]leucine by uterine gland tubules in vivo and in vitro. A linear dose response relationship was demonstrated in vitro with extract concentrations ranging from 1 × 10^-4 to 1 × 10^-2 brains μl^-1. The maximum response, a > 300% increase in the rate of protein and amino acid synthesis, was achieved with as little as 1 × 10^-2 brains μl^-1 The concentration of active factor(s) in the brain declined during a single interlarval period coincident with the period of release of secretion associated with larval growth. The stimulatory activity in brain extracts was destroyed by proteolytic enzymes indicating that it is probably a protein or peptide. Results suggest that the active factor(s) is a hormone responsible for the stimulation of uterine gland protein synthesis essential for larval nutrition.     

Influence of temperature changes on larviposition rhythm in the tsetse fly, Glossina morsitans

ABSTRACT. The hourly and quarter-hourly distribution of larval deposition by female Glossina morsitans Westw. was studied at various temperatures. At constant temperature and humidity, peak larviposition occurred 8–9 h after lights on. The effect of confining the flies to daily (LD 12:12 h) regimes of at least twenty-five consecutive cycles that included a sudden increase in temperature of c. 6°C for 2 h was a significant reduction in depositions during each period of increased temperature, and a significant increase before the heat impulse. When the temperature was allowed to fall rapidly, larviposition rate doubled in the following 15 min.