title: Seasonal Dynamics in the Chemistry and Structure of the Fat Bodies of Bumblebee Queens.
abstract: 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.
authors.affiliation: Agricultural Research, Ltd., Troubsko, Czech Republic.
authors.forename: Alena
authors.initials: A
authors.lastname: Votavová
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.|Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.
authors.forename: Aleš
authors.initials: A
authors.lastname: Tomčala
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Edita
authors.initials: E
authors.lastname: Kofroňová
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Michaela
authors.initials: M
authors.lastname: Kudzejová
authors.affiliation: Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Šobotník
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Jiroš
authors.affiliation: Agricultural Research, Ltd., Troubsko, Czech Republic.
authors.forename: Olga
authors.initials: O
authors.lastname: Komzáková
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Irena
authors.initials: I
authors.lastname: Valterová
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001516:Bees / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D005216:Fat Body / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D006605:Hibernation; D012621:Seasons
chemical_list: D005227:Fatty Acids