Changes in the Composition of Triacylglycerols in the Fat Bodies of Bumblebee Males During Their Lifetime

Two‐dimensional comprehensive gas chromatography (GC×GC) coupled with mass detection was used as a tool for biosynthetic studies of bumblebee pheromones. Prior to biosynthetic experiments, the chromatographic behaviour of isotopically modified esters in the GC×GC system as well as their behaviour in mass detection was studied. The male marking pheromones of Bombus lucorum, Bombus lapidarius and Bombus terrestris were investigated. Main pheromonal components are ethyl tetradec‐9‐enoate (53 %) and ethyl dodecanoate (6 %) in B. lucorum, hexadec‐9‐en‐1‐ol (52 %) and hexadecan‐1‐ol (31 %) in B. lapidarius, and 2,3‐dihydrofarnesol (58 %) and ethyl dodecanoate (15 %) in B. terrestris. The research strategy was based on 1) in vivo incubation of isotopically (2H, 13C) modified fatty acids (FAs) and analysis of their metabolites and 2) feeding experiments with 2H‐ and 13C‐labelled FAs mixed with food. It was observed that labelled FAs were modified into the most abundant aliphatic compounds present in labial gland secretions. In feeding experiments, the labelled FAs were transformed into pheromone components. Transport of the FA precursors from the fat body through haemolymph was confirmed. The results show that FAs, stored in the form of triacylglycerols in the fat body, are likely to participate in the biosynthesis of some aliphatic pheromone components.

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“…Jiroš et al. found that bumblebee males hatch with fully developed FBs,36 which could serve as a source of FAs.…”

Section: Resultsmentioning

confidence: 99%

Biosynthetic Studies of the Male Marking Pheromone in Bumblebees by Using Labelled Fatty Acids and Two‐Dimensional Gas Chromatography with Mass Detection

et al. 2015

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“…Beenakkers et al [ 35 ] reported on the existence of two different acylglycerol pools in FB with expected differences in the manner of their utilization. Metabolic TG belonging to group A ( Fig 4 ) dominate also in the males' FB [ 15 ] while queen-specific TG change during the queens' life. This may indicate their relationship to overwintering and possibly also to future egg formation and/or development with their special metabolic requirements beyond the needs of short-lived males.…”

Section: Discussionmentioning

confidence: 99%

“…HPLC/MS with atmospheric pressure chemical ionization (APCI) was used for the TG analyses as described by Jiroš et al [ 15 ]. In order to evaluate the total lipid composition, we used HPLC combined with electrospray ionization mass-spectrometry (MS-ESI) (modified according to ref.…”

Section: Methodsmentioning

confidence: 99%

“…Knowledge as to the composition of bumblebee energy reserves consists in only a few studies, reporting namely quantifications of glycogen content in freshly emerged queens and workers [ 12 ] and male triacylglycerols (TG) profile in several bumblebee species [ 13 – 15 ]. Unlike short-lived males with a single dominant activity, queens are exposed to many energy-demanding processes.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Dynamics in the Chemistry and Structure of the Fat Bodies of Bumblebee Queens

Votavová¹,

Tomčala

Kofroňová

et al. 2015

PLoS ONE

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Insects’ fat bodies are responsible for nutrient storage and for a significant part of intermediary metabolism. Thus, it can be expected that the structure and content of the fat body will adaptively change, if an insect is going through different life stages. Bumblebee queens belong to such insects as they dramatically change their physiology several times over their lives in relation to their solitary overwintering, independent colony foundation stage, and during the colony life-cycle ending in the senescent stage. Here, we report on changes in the ultrastructure and lipid composition of the peripheral fat body of Bombus terrestris queens in relation to seasonal changes in the queens’ activity. Six life stages are defined and evaluated in particular: pharate, callow, before and after hibernation, egg-laying, and senescence. Transmission electron microscopy revealed that the fat body contained two main cell types–adipocytes and oenocytes. Only adipocytes reveal important changes related to the life phase, and mostly the ration between inclusion and cytoplasm volume varies among particular stages. Both electron microscopy and chemical analyses of lipids highlighted seasonal variability in the quantity of the stored lipids, which peaked prior to hibernation. Triacylglycerols appeared to be the main energy source during hibernation, while the amount of glycogen before and after hibernation remained unchanged. In addition, we observed that the representation of some fatty acids within the triacylglycerols change during the queen’s life. Last but not least, we show that fat body cell membranes do not undergo substantial changes concerning phospholipid composition in relation to overwintering. This finding supports the hypothesis that the cold-adaptation strategy of bumblebee queens is more likely to be based on polyol accumulation than on the restructuring of lipid membranes.

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“…Established protocols for year‐round breeding of Bombus terrestris provides a continuous source of specimens of defined ages and physiological condition. This allows for the investigation of temporal changes in MP composition, along with other aspects of Bombus terrestris physiology and behaviour (Šobotník et al ., ; Žáček et al ., ; Jiroš et al ., ; Jarau et al ., ; Brabcová et al ., ; Buček et al ., ; Prchalová et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Exploring complex pheromone biosynthetic processes in the bumblebee male labial gland by RNA sequencing

Buček

Brabcová

Vogel

et al. 2016

Insect Molecular Biology

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Male marking pheromones (MPs) are used by the majority of bumblebee species (Hymenoptera: Apidae), including a commercially important greenhouse pollinator, the buff-tailed bumblebee (Bombus terrestris), to attract conspecific females. MP biosynthetic processes in the cephalic part of the bumblebee male labial gland (LG) are of extraordinary complexity, involving enzymes of fatty acid and isoprenoid biosynthesis, which jointly produce more than 50 compounds. We employed a differential transcriptomic approach to identify candidate genes involved in MP biosynthesis by sequencing Bombus terrestris LG and fat body (FB) transcriptomes. We identified 12 454 abundantly expressed gene products (reads per kilobase of exon model per million mapped reads value > 1) that had significant hits in the GenBank nonredundant database. Of these, 876 were upregulated in the LG (> 4-fold difference). We identified more than 140 candidate genes potentially involved in MP biosynthesis, including esterases, fatty acid reductases, lipases, enzymes involved in limited fatty acid chain shortening, neuropeptide receptors and enzymes involved in biosynthesis of triacylglycerols, isoprenoids and fatty acids. For selected candidates, we confirmed their abundant expression in LG using quantitative real-time reverse transcription-PCR (qRT-PCR). Our study shows that the Bombus terrestris LG transcriptome reflects both fatty acid and isoprenoid MP biosynthetic processes and identifies rational gene targets for future studies to disentangle the molecular basis of MP biosynthesis. Additionally, LG and FB transcriptomes enrich the available transcriptomic resources for Bombus terrestris.

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Changes in the Composition of Triacylglycerols in the Fat Bodies of Bumblebee Males During Their Lifetime

Cited by 7 publications

References 37 publications

Biosynthetic Studies of the Male Marking Pheromone in Bumblebees by Using Labelled Fatty Acids and Two‐Dimensional Gas Chromatography with Mass Detection

Biosynthetic Studies of the Male Marking Pheromone in Bumblebees by Using Labelled Fatty Acids and Two‐Dimensional Gas Chromatography with Mass Detection

Seasonal Dynamics in the Chemistry and Structure of the Fat Bodies of Bumblebee Queens

Exploring complex pheromone biosynthetic processes in the bumblebee male labial gland by RNA sequencing

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