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Concurrence in the ability for lipid synthesis between life stages in insects

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ABSTRACT

The ability to synthesize lipids is critical for an organism’s fitness; hence, metabolic pathways, underlying lipid synthesis, tend to be highly conserved. Surprisingly, the majority of parasitoids deviate from this general metabolic model by lacking the ability to convert sugars and other carbohydrates into lipids. These insects spend the first part of their life feeding and developing in or on an arthropod host, during which they can carry over a substantial amount of lipid reserves. While many parasitoid species have been tested for lipogenic ability at the adult life stage, it has remained unclear whether parasitoid larvae can synthesize lipids. Here we investigate whether or not several insects can synthesize lipids during the larval stage using three ectoparasitic wasps (developing on the outside of the host) and the vinegar fly Drosophila melanogaster that differ in lipogenic ability in the adult life stage. Using feeding experiments and stable isotope tracing with gas chromatography/mass spectrometry, we first confirm lipogenic abilities in the adult life stage. Using topical application of stable isotopes in developing larvae, we then provide clear evidence of concurrence in lipogenic ability between larval and adult life stages in all species tested.

No MeSH data available.


Deuterium incorporation into shorter chain fatty acids (C12 : 0 + C14 : 0), palmitate and palmitoleate (C16 : 0 + C16 : 1) and longer chain fatty acids (C18 : 0 + C18 : 1) for adults. IS refers to the internal standard (C17 : 0) that was added as a control. Asterisks indicate significant differences in incorporation between adults receiving deuterium treatment and those receiving water controls. Points and error bars denote log-transformed adjusted mean per cent incorporation and 95% CIs, respectively. Letters not shared within chain length type indicate significant differences in rates of incorporation between species (α=0.05).
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RSOS160815F1: Deuterium incorporation into shorter chain fatty acids (C12 : 0 + C14 : 0), palmitate and palmitoleate (C16 : 0 + C16 : 1) and longer chain fatty acids (C18 : 0 + C18 : 1) for adults. IS refers to the internal standard (C17 : 0) that was added as a control. Asterisks indicate significant differences in incorporation between adults receiving deuterium treatment and those receiving water controls. Points and error bars denote log-transformed adjusted mean per cent incorporation and 95% CIs, respectively. Letters not shared within chain length type indicate significant differences in rates of incorporation between species (α=0.05).

Mentions: After feeding on sugar–water with or without the stable isotope deuterium, incorporation was traced into the FA fraction of all species. Significant main effects were observed for species, treatment and FA chain length, as well as their interactions (figure 1 and table 1). No incorporation of deuterium was observed in the parasitoid E. vuilleti (t8.87=0.13, p=0.90), whereas the vinegar fly D. melanogaster (t8.15=5.99, p=0.0003), and the parasitoids G. agilis (t8.04=6.60, p=0.0002) and G. areator (t9.04=6.31, p=0.0001) readily incorporated deuterium in their FA fractions. Drosophila melanogaster synthesized the shorter chain FAs (C12 : 0 + C14 : 0) at a higher rate than G. agilis and G. areator (t2101.32=20.698, p<0.001), whereas the longer chain FAs (C18 : 0 + C18 : 1) were synthesized at higher rates in both Gelis species (p<0.0001 for all contrasts).Figure 1.


Concurrence in the ability for lipid synthesis between life stages in insects
Deuterium incorporation into shorter chain fatty acids (C12 : 0 + C14 : 0), palmitate and palmitoleate (C16 : 0 + C16 : 1) and longer chain fatty acids (C18 : 0 + C18 : 1) for adults. IS refers to the internal standard (C17 : 0) that was added as a control. Asterisks indicate significant differences in incorporation between adults receiving deuterium treatment and those receiving water controls. Points and error bars denote log-transformed adjusted mean per cent incorporation and 95% CIs, respectively. Letters not shared within chain length type indicate significant differences in rates of incorporation between species (α=0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383825&req=5

RSOS160815F1: Deuterium incorporation into shorter chain fatty acids (C12 : 0 + C14 : 0), palmitate and palmitoleate (C16 : 0 + C16 : 1) and longer chain fatty acids (C18 : 0 + C18 : 1) for adults. IS refers to the internal standard (C17 : 0) that was added as a control. Asterisks indicate significant differences in incorporation between adults receiving deuterium treatment and those receiving water controls. Points and error bars denote log-transformed adjusted mean per cent incorporation and 95% CIs, respectively. Letters not shared within chain length type indicate significant differences in rates of incorporation between species (α=0.05).
Mentions: After feeding on sugar–water with or without the stable isotope deuterium, incorporation was traced into the FA fraction of all species. Significant main effects were observed for species, treatment and FA chain length, as well as their interactions (figure 1 and table 1). No incorporation of deuterium was observed in the parasitoid E. vuilleti (t8.87=0.13, p=0.90), whereas the vinegar fly D. melanogaster (t8.15=5.99, p=0.0003), and the parasitoids G. agilis (t8.04=6.60, p=0.0002) and G. areator (t9.04=6.31, p=0.0001) readily incorporated deuterium in their FA fractions. Drosophila melanogaster synthesized the shorter chain FAs (C12 : 0 + C14 : 0) at a higher rate than G. agilis and G. areator (t2101.32=20.698, p<0.001), whereas the longer chain FAs (C18 : 0 + C18 : 1) were synthesized at higher rates in both Gelis species (p<0.0001 for all contrasts).Figure 1.

View Article: PubMed Central - PubMed

ABSTRACT

The ability to synthesize lipids is critical for an organism&rsquo;s fitness; hence, metabolic pathways, underlying lipid synthesis, tend to be highly conserved. Surprisingly, the majority of parasitoids deviate from this general metabolic model by lacking the ability to convert sugars and other carbohydrates into lipids. These insects spend the first part of their life feeding and developing in or on an arthropod host, during which they can carry over a substantial amount of lipid reserves. While many parasitoid species have been tested for lipogenic ability at the adult life stage, it has remained unclear whether parasitoid larvae can synthesize lipids. Here we investigate whether or not several insects can synthesize lipids during the larval stage using three ectoparasitic wasps (developing on the outside of the host) and the vinegar fly Drosophila melanogaster that differ in lipogenic ability in the adult life stage. Using feeding experiments and stable isotope tracing with gas chromatography/mass spectrometry, we first confirm lipogenic abilities in the adult life stage. Using topical application of stable isotopes in developing larvae, we then provide clear evidence of concurrence in lipogenic ability between larval and adult life stages in all species tested.

No MeSH data available.