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- Burdon, Rosalie C. F., et al.
(författare)
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Spatiotemporal floral scent variation of Penstemon digitalis
- 2015
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 41:7, s. 641-650
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Tidskriftsartikel (refereegranskat)abstract
- Variability in floral volatile emissions can occur temporally through floral development, during diel cycles, as well as spatially within a flower. These spatiotemporal patterns are hypothesized to provide additional information to floral visitors, but they are rarely measured, and their attendant hypotheses are even more rarely tested. In Penstemon digitalis, a plant whose floral scent has been shown to be under strong phenotypic selection for seed fitness, we investigated spatiotemporal variation in floral scent by using dynamic headspace collection, respectively solid-phase microextraction, and analyzed the volatile samples by combined gas chromatography-mass spectrometry. Total volatile emission was greatest during flowering and peak pollinator activity hours, suggesting its importance in mediating ecological interactions. We also detected tissue and reward-specific compounds, consistent with the hypothesis that complexity in floral scent composition reflects several ecological functions. In particular, we found tissue-specific scents for the stigma, stamens, and staminode (a modified sterile stamen common to all Penstemons). Our findings emphasize the dynamic nature of floral scents and highlight a need for greater understanding of ecological and physiological mechanisms driving spatiotemporal patterns in scent production.
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| 69. |
- Burdon, Rosalie, 1988-, et al.
(författare)
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Scented nectar and the challenge of measuring honest signals in pollination
- 2020
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Ingår i: Journal of Ecology. - : WILEY. - 0022-0477 .- 1365-2745. ; 108:5, s. 2132-2144
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Tidskriftsartikel (refereegranskat)abstract
- Nectar scents are thought to function as honest signals of reward used by pollinators, but this hypothesis has rarely been tested. UsingPenstemon digitalis, we examined honest signalling of the nectar volatile (S)-(+)-linalool and pollinator responses to linalool in both field and laboratory settings. Because our previous work showed that linalool emission was associated with higher female fitness and that nectar is scented with linalool, we hypothesized that linalool was an honest signal of nectar reward. To assess honesty, we measured linalool-nectar associations including nectar volume, sugar amount, concentration and production rate for inflorescences and flowers in several populations. We also assessed whetherBombus impatiens, the main pollinator ofP. digitalisat our sites, can use linalool as a foraging signal. We supplemented real or artificial flowers in the field and laboratory with varying linalool-nectar combinations to measure pollinator behavioural responses. We found that an inflorescence's linalool emissions could be used to predict nectar rewards inP. digitalis, but this was driven by indirect associations with display size rather than directly advertising more profitable flowers. For flowers within inflorescences there was also no evidence for an association between signal and reward. Field tests of bumblebee behaviour were inconclusive. However, in laboratory assays, bumblebees generally used variation in linalool emissions to choose more profitable flowers, demonstrating they can detect differences in linalool emitted byP. digitalisand associate them with reward profitability. These results suggest experiments that decouple display size, scent and reward are necessary to assess whether (and when) bees prefer higher linalool emissions. Bees preferred nectars with lower linalool concentrations when linalool flavoured the nectar solution, suggesting the potential for conflicting pressures on scent emission in the field. Synthesis. Our results highlight the challenges of assessing function for traits important to fitness and suggest that the perception of floral signalling honesty may depend on whether pollinators use inflorescences or flowers within inflorescences when making foraging decisions. We conclude that future research on honest signalling in flowering plants, as well as its connection to phenotypic selection, should explicitly define honesty, in theoretical and experimental contexts.
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| 70. |
- Curtis, Michael W., et al.
(författare)
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Identification of amino acid domains of Borrelia burgdorferi P66 that are surface exposed and important for localization, oligomerization, and porin function of the protein
- 2022
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Ingår i: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media S.A.. - 2235-2988. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- P66, a bifunctional integral outer membrane protein, is necessary for Borrelia burgdorferi to establish initial infection and to disseminate in mice. The integrin binding function of P66 facilitates extravasation and dissemination, but the role of its porin function during murine infection has not been investigated. A limitation to studying P66 porin function during mammalian infection has been the lack of structural information for P66. In this study, we experimentally characterized specific domains of P66 with regard to structure and function. First, we aligned the amino acid sequences of P66 from Lyme disease-causing Borrelia and relapsing fever-causing Borrelia to identify conserved and unique domains between these disease-causing clades. Then, we examined whether specific domains of P66 are exposed on the surface of the bacteria by introducing c-Myc epitope tags into each domain of interest. The c-Myc epitope tag inserted C-terminally to E33 (highly conserved domain), to T187 (integrin binding region domain and a non-conserved domain), and to E334 (non-conserved domain) were all detected on the surface of Borrelia burgdorferi. The c-Myc epitope tag inserted C-terminally to E33 and D303 in conserved domains disrupted P66 oligomerization and porin function. In a murine model of infection, the E33 and D303 mutants exhibited decreased infectivity and dissemination. Taken together, these results suggest the importance of these conserved domains, and potentially P66 porin function, in vivo.
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