22 research outputs found
Lack of phenotypic and evolutionary cross-resistance against parasitoids and pathogens in Drosophila melanogaster
No full textBackgroundWhen organisms are attacked by multiple natural enemies, the evolution of a resistance mechanism to one natural enemy will be influenced by the degree of cross-resistance to another natural enemy. Cross-resistance can be positive, when a resistance mechanism against one natural enemy also offers resistance to another; or negative, in the form of a trade-off, when an increase in resistance against one natural enemy results in a decrease in resistance against another. Using Drosophila melanogaster, an important model system for the evolution of invertebrate immunity, we test for the existence of cross-resistance against parasites and pathogens, at both a phenotypic and evolutionary level.MethodsWe used a field strain of D. melanogaster to test whether surviving parasitism by the parasitoid Asobara tabida has an effect on the resistance against Beauveria bassiana, an entomopathogenic fungus; and whether infection with the microsporidian Tubulinosema kingi has an effect on the resistance against A. tabida. We used lines selected for increased resistance to A. tabida to test whether increased parasitoid resistance has an effect on resistance against B. bassiana and T. kingi. We used lines selected for increased tolerance against B. bassiana to test whether increased fungal resistance has an effect on resistance against A. tabida.Results/ConclusionsWe found no positive cross-resistance or trade-offs in the resistance to parasites and pathogens. This is an important finding, given the use of D. melanogaster as a model system for the evolution of invertebrate immunity. The lack of any cross-resistance to parasites and pathogens, at both the phenotypic and the evolutionary level, suggests that evolution of resistance against one class of natural enemies is largely independent of evolution of resistance against the other
Accessory gland size predicts time to seuxal maturity and mating frequency in the stalk-eyed fly, Cyrtodiopsis dalmanni
No full textAge at first reproduction is an extremely important life-history trait. Several factors such as nutritional state and age-specific fecundity have been shown to influence time to sexual maturity; however, little work has been done in insects. We addressed this in a stalk-eyed fly (Cyrtodiopsis dalmanni), by testing the hypothesis that time to sexual maturity is associated with the development of male internal reproductive structures. We found that sexual maturity was attained after an increased rate of growth in the accessory glands, several days after mature sperm bundles, and motile sperm were observed in the testes. Although testis development is essential, the results suggest that accessory gland growth is more closely associated with the time taken to reach sexual maturity than is testis growth. When we manipulated the growth of testes and accessory glands via a dietary manipulation, we found that delayed growth rates increased the time taken to reach sexual maturity. Among the delayed individuals, sexually mature males had larger accessory glands, but not testes, than did immature males. In adult males, mating frequency was significantly positively correlated with accessory gland size, but not with testis length or body size. We conclude that accessory gland size is a critical determinant of sexual maturity and male mating frequency in this species
Accessory gland size influences time to sexual maturity and mating frequency in the stalk-eyed fly, Cyrtodiopsis dalmanni
No full textAuthor Correction: Q-RAI data-independent acquisition for lipidomic quantitative profiling
No full textThe essential neutral sphingomyelinase is involved in the trafficking of the variant surface glycoprotein in the bloodstream form of Trypanosoma brucei
No full textSphingomyelin is the main sphingolipid in Trypanosoma brucei, the causative agent of African sleeping sickness. In vitro and in vivo characterization of the T. brucei neutral sphingomyelinase demonstrates that it is directly involved in sphingomyelin catabolism. Gene knockout studies in the bloodstream form of the parasite indicate that the neutral sphingomyelinase is essential for growth and survival, thus highlighting that the de novo biosynthesis of ceramide is unable to compensate for the loss of sphingomyelin catabolism. The phenotype of the conditional knockout has given new insights into the highly active endocytic and exocytic pathways in the bloodstream form of T. brucei. Hence, the formation of ceramide in the endoplasmic reticulum affects post-Golgi sorting and rate of deposition of newly synthesized GPI-anchored variant surface glycoprotein on the cell surface. This directly influences the corresponding rate of endocytosis, via the recycling endosomes, of pre-existing cell surface variant surface glycoprotein. The trypanosomes use this coupled endocytic and exocytic mechanism to maintain the cell density of its crucial variant surface glycoprotein protective coat. TbnSMase is therefore genetically validated as a drug target against African trypanosomes, and suggests that interfering with the endocytic transport of variant surface glycoprotein is a highly desirable strategy for drug development against African trypanosomasis.Peer reviewe
Fungal resistance of flies surviving parasitism.
No full text<p>Mean time to death (in days) for <i>Drosophila melanogaster</i> adult flies that were either infected with <i>Beauveria bassiana</i> (F; grey bars) or uninfected (U; white bars), depending on whether they had been parasitised by <i>Asobara tabida</i> as a larvae (Par; right side of panel) or had not been parasitised (Unp; left side of panel). The two bars within each treatment combination represent the results of the two experimental blocks. Bars show mean ± s.e.</p
Encapsulation ability of larvae infected with microsporidia.
No full text<p>Rate of encapsulation of <i>Asobara tabida</i> eggs by <i>Drosophila melanogaster</i> larvae which had either been infected with <i>Tubulinosema kingi</i> (M; grey bar) or had not been infected (U; white bar). Bars show mean ± s.e.</p
Encapsulation ability of larvae selected for fungal resistance.
No full text<p>Rate of encapsulation of <i>Asobara tabida</i> eggs by <i>Drosophila melanogaster</i> larvae which had either been selected for tolerance to <i>Beauveria bassiana</i> (S; grey bar) or had not been selected (U; white bar). Bars show mean ± s.e.</p
Resistance to microsporidia of flies selected for parasitoid resistance.
No full text<p>Early fecundity of <i>Drosophila melanogaster</i> females adult flies that were either infected with <i>Tubulinosema kingi</i> (M; grey bars) or uninfected (U; white bars), depending on whether they had been selected for increased resistance to <i>Asobara tabida</i> (Sel; right side of panel) or had not been selected (Con; left side of panel). Bars show mean ± s.e.</p
Cross-resistance in <i>Drosophila melanogaster</i>.
No full text<p>Overview of the existence of cross-resistance, and its direction if present, in <i>Drosophila melanogaster</i> in response to various combinations of parasites and pathogens. Based on data from this paper (indicated by an *) and the literature (none = no cross-resistance detected; empty cell = cross-resistance not tested).</p
