TY - JOUR A1 - Değirmenci, Laura A1 - Rogé Ferreira, Fabio Luiz A1 - Vukosavljevic, Adrian A1 - Heindl, Cornelia A1 - Keller, Alexander A1 - Geiger, Dietmar A1 - Scheiner, Ricarda T1 - Sugar perception in honeybees JF - Frontiers in Physiology N2 - Honeybees (Apis mellifera) need their fine sense of taste to evaluate nectar and pollen sources. Gustatory receptors (Grs) translate taste signals into electrical responses. In vivo experiments have demonstrated collective responses of the whole Gr-set. We here disentangle the contributions of all three honeybee sugar receptors (AmGr1-3), combining CRISPR/Cas9 mediated genetic knock-out, electrophysiology and behaviour. We show an expanded sugar spectrum of the AmGr1 receptor. Mutants lacking AmGr1 have a reduced response to sucrose and glucose but not to fructose. AmGr2 solely acts as co-receptor of AmGr1 but not of AmGr3, as we show by electrophysiology and using bimolecular fluorescence complementation. Our results show for the first time that AmGr2 is indeed a functional receptor on its own. Intriguingly, AmGr2 mutants still display a wildtype-like sugar taste. AmGr3 is a specific fructose receptor and is not modulated by a co-receptor. Eliminating AmGr3 while preserving AmGr1 and AmGr2 abolishes the perception of fructose but not of sucrose. Our comprehensive study on the functions of AmGr1, AmGr2 and AmGr3 in honeybees is the first to combine investigations on sugar perception at the receptor level and simultaneously in vivo. We show that honeybees rely on two gustatory receptors to sense all relevant sugars. KW - AmGr1 KW - AmGr2 KW - AmGr3 KW - sugar responsiveness KW - proboscis extension response (PER) KW - gustatory receptors (Grs) KW - honeybee taste perception Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-302284 SN - 1664-042X VL - 13 ER - TY - JOUR A1 - Lu, Jinping A1 - Dreyer, Ingo A1 - Dickinson, Miles Sasha A1 - Panzer, Sabine A1 - Jaślan, Dawid A1 - Navarro-Retamal, Carlos A1 - Geiger, Dietmar A1 - Terpitz, Ulrich A1 - Becker, Dirk A1 - Stroud, Robert M. A1 - Marten, Irene A1 - Hedrich, Rainer T1 - Vicia faba SV channel VfTPC1 is a hyperexcitable variant of plant vacuole two pore channels JF - eLife N2 - To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca\(^{2+}\). In our search for species-dependent functional TPC1 channel variants with different luminal Ca\(^{2+}\) sensitivity, we found in total three acidic residues present in Ca\(^{2+}\) sensor sites 2 and 3 of the Ca\(^{2+}\)-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca\(^{2+}\). When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca\(^{2+}\) sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca\(^{2+}\) sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche. KW - A. thaliana KW - Brassicaceae KW - Fabaceae KW - pore KW - potassium channel KW - voltage gating KW - vacuolar calcium sensor Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-350264 VL - 12 ER -