Kings and queens of termites, like queens of other advanced eusocial insects, are endowed with admirable longevity, which dramatically exceeds the life expectancies of their non-reproducing nest-mates and related solitary insects. In the quest to find the mechanisms underlying the longevity of termite reproductives, we focused on somatic maintenance mediated by telomerase. This ribonucleoprotein is well established for pro-longevity functions in vertebrates, thanks primarily to its ability of telomere extension. However, its participation in lifespan regulation of insects, including the eusocial taxa, remains understudied. Here, we report a conspicuous increase of telomerase abundance and catalytic activity in the somatic organs of primary and secondary reproductives of the termite Prorhinotermes simplex and confirm a similar pattern in two other termite species. These observations stand in contrast with the telomerase downregulation characteristic for most adult somatic tissues in vertebrates and also in solitary insects and non-reproducing castes of termites. At the same time, we did not observe caste-specific differences in telomere lengths that might explain the differential longevity of termite castes. We conclude that although the telomerase activation in termite reproductives is in line with the broadly assumed association between telomerase and longevity, its direct phenotypic impact remains to be elucidated.

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.

The fungus Geotrichum candidum 4013 produces two types of lipases (extracellular and cell-bound). Both enzymes were tested for their hydrolytic ability to pnitrophenyl esters and compounds having a structure similar to the original substrate (triacylglycerols). Higher lipolytic activity of extracellular lipase was observed when triacylglycerols of medium-(C12) and long-(C18) chain fatty acids were used as substrates. Cell-bound lipase preferentially hydrolysed trimyristate (C14). The differences in the abilities of these two enzymes to hydrolyse p-nitrophenyl esters were observed as well. The order of extracellular lipase hydrolysis relation velocity was as follows: p-nitrophenyl decanoate > p-nitrophenyl caprylate > p-nitrophenyl laurate > p-nitrophenyl palmitate > p-nitrophenyl stearate. The cell-bound lipase indicates preference for p-nitrophenyl palmitate. The most striking differences in the ratios between the activity of both lipases (extracellular : cell-bound) towards different fatty acid methyl esters were 2.2 towards methyl hexanoate and 0.46 towards methyl stearate (C18). The Michaelis constant (K m ) and maximum reaction rate (V max ) for p-nitrophenyl palmitate hydrolysis of cell-bound lipase were significantly higher (K m 2.462 mM and V max 0.210 U/g/min) than those of extracellular lipase (K m 0.406 mM and V max 0.006 U/g/min).

BackgroundIn addition to their general role in the hydrolysis of storage lipids, bumblebee lipases can participate in the biosynthesis of fatty acids that serve as precursors of pheromones used for sexual communication.ResultsWe studied the temporal dynamics of lipolytic activity in crude extracts from the cephalic part of Bombus terrestris labial glands. Extracts from 3-day-old males displayed the highest lipolytic activity. The highest lipase gene expression level was observed in freshly emerged bumblebees, and both gene expression and lipase activity were lower in bumblebees older than 3 days. Lipase was purified from labial glands, further characterized and named as BT-1. The B. terrestris orthologue shares 88% sequence identity with B. impatiens lipase HA. The molecular weight of B. terrestris lipase BT-1 was approximately 30 kDa, the pH optimum was 8.3, and the temperature optimum was 50°C. Lipase BT-1 showed a notable preference for C8-C10 p-nitrophenyl esters, with the highest activity toward p-nitrophenyl caprylate (C8). The Michaelis constant (Km) and maximum reaction rate (Vmax) for p-nitrophenyl laurate hydrolysis were Km = 0.0011 mM and Vmax = 0.15 U/mg.ConclusionThis is the first report describing neutral lipase from the labial gland of B. terrestris. Our findings help increase understanding of its possible function in the labial gland.