Biology subjects

Hedenstroem, E.

Publications and source records attributed to Hedenstroem, E..

3 recordsLinked to original sources

bioRxiv2020

The human odorant receptor OR10A6 is tuned to the pheromone of the commensal fruit fly Drosophila melanogaster

BackgroundAll living things speak chemical. The challenge is to discover the vocabulary, the volatile odorant chemicals that enable communication across phylogenies and to translate them to physiological, behavioural and ecological function. Olfactory receptors (ORs) interface animals with airborne odorants. Expression of single ORs in human embryonic kidney cells (HEK-293) makes it possible to interrogate ORs with synthetic chemicals and to identify cognate ligands that convey olfactory information. ResultsThe cosmopolitan strain of the vinegar fly Drosophila melanogaster has accompanied the human expansion out of Africa, more than ten thousand years ago. These flies are strictly anthropophilic and depend on human resources and housing for survival, particularly in colder climate zones. Curiously, humans sense the scent of a single fly, and more precisely the female pheromone (Z)-4 undecenal (Z4-11Al), at 10 ng/mL (0.06 {micro}mol/L). A screening of all functional human ORs in a HEK-293 assay provides an explanation for this astounding sensitivity, as it shows that OR10A6, one of the most highly expressed human ORs, is specifically tuned to Z4-11Al. Chemical analysis of fly effluvia confirms that cosmopolitan D. melanogaster females release Z4-11Al, while females of an African fly strain from Zimbabwe release a 1:3-blend of Z4-11Al and (Z)-4 nonenal (Z4-9Al). Interestingly, a blend of Z4-9Al and Z4-11Al produces a different aroma than the the single compounds, which is why we readily differentiate cosmopolitan and Zimbabwe flies by nose. ConclusionThat we sensitively and specifically perceive the fly pheromone Z4-11Al suggests that it is a component of human odour scenes. This may have afforded a sensory drive during adaptation of commensal flies to human habitats and selected for a role of Z4-11Al in fly aggregation and premating communication. Screening ORs for key ligands leads to the discovery of messenger chemicals that enable chemical communication among and betwen vertebrate and invertebrate animals.

animal behavior and cognition↗

bioRxiv2019

Yeast volatomes differentially effect larval feeding in an insect herbivore

Yeasts form mutualistic interactions with insects. Hallmarks of this interaction include provision of essential nutrients, while insects facilitate yeast dispersal and growth on plant substrates. A phylogenetically ancient, chemical dialogue coordinates this interaction, where the vocabulary, the volatile chemicals that mediate the insect response, remains largely unknown. Here, we employed gas chromatography-mass spectrometry (GC-MS), followed by hierarchical cluster (HCA) and orthogonal partial least square discriminant analysis (OPLS-DA), to profile the volatomes of six Metschnikowia spp., Cryptococcus nemorosus and brewers yeast Saccharomyces cerevisiae. The yeasts, which are all found in association with insects feeding on foliage or fruit, emit characteristic, species-specific volatile blends that reflect the phylogenetic context. Species-specificity of these volatome profiles aligned with differential feeding of cotton leafworm larvae Spodoptera littoralis on these yeasts. Bioactivity correlates with yeast ecology; phylloplane species elicited a stronger response than fruit yeasts, and larval discrimination may provide a mechanism for establishment of insect-yeast associations. The yeast volatomes contained a suite of insect attractants known from plant and especially floral headspace, including (Z)-hexenyl acetate, ethyl (2E,4Z)-deca-2,4-dienoate (pear ester), (3E)-4,8-dimethylnona-1,3,7-triene (DMNT), linalool, -terpineol, {beta}-myrcene or (E,E)-a-farnesene. A wide overlap of yeast and plant volatiles, notably floral scents further emphasizes the prominent role of yeasts in plant-microbe-insect relationships including pollination. The knowledge of insect-yeast interactions can be readily brought to practical application, live yeasts or yeast metabolites mediating insect attraction provide an ample toolbox for the development of sustainable insect management.\n\nIMPORTANCEYeasts interface insect herbivores with their food plants. Communication depends on volatile metabolites, and decoding this chemical dialogue is key to understanding the ecology of insect-yeast interactions. This study explores the volatomes of eight yeast species which have been isolated from foliage, flowers or fruit, and from plant-feeding insects. They each release a rich bouquet of volatile metabolites, including a suite of known insect attractants from plant and floral scent. This overlap underlines the phylogenetic dimension of insect-yeast associations, which according to the fossil record, long predate the appearance of flowering plants. Volatome composition is characteristic for each species, aligns with yeast taxonomy, and is further reflected by a differential behavioural response of cotton leafworm larvae, which naturally feed on foliage of a wide spectrum of broad-leaved plants. Larval discrimination may establish and maintain associations with yeasts and is also a substrate for designing sustainable insect management techniques.

microbiology↗

bioRxiv2016

The Drosophila pheromone Z4-11Al is encoded together with habitat olfactory cues and mediates species-specific communication

Mate recognition in animals evolves during niche adaptation and involves habitat and social olfactory signals. Drosophila melanogaster is attracted to fermenting fruit for feeding and egg-laying. We show that, in addition, female flies release a pheromone (Z)4-undecenal (Z4-11Al), that elicits flight attraction in both sexes. The biosynthetic precursor of Z4-11Al is the cuticular hydrocarbon (Z,Z)-7,11-heptacosadiene (7,11-HD), which is known to afford reproductive isolation between D. melanogaster and D. simulans. A pair of alternatively spliced receptors, Or69aB and Or69aA, is tuned to Z4-11Al and to food olfactory cues, respectively. These receptors are co-expressed in the same olfactory sensory neurons, and feed into a neural circuit mediating species-specific, long-range communication: the close relative D. simulans does not respond. That Or69aA and Or69aB have adopted dual olfactory traits highlights the interplay of habitat and social signals in mate finding. These olfactory receptor genes afford a collaboration between natural and sexual selection, which has the potential to drive phylogenetic divergence.

animal behavior and cognition↗