https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 Two modes of excytosis from synaptosomes are differentially regulated by protein phosphatase types 2A and 2B https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1634 Sat 24 Mar 2018 08:30:35 AEDT ]]> F-actin-dependent endocytosis of cell wall pectins in meristematic root cells: insights from Brefeldin A-induced compartments https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1474 4)-β-D-galactan side chains of rhamnogalacturonan I were internalized into BFA compartments. In contrast, Golgi-derived secretory (esterified up to 80%) homogalacturonan pectins localized to the cytoplasm in control cells and did not accumulate within characteristic BFA compartments. Latrunculin B-mediated depolymerization of F-actin inhibited internalization and accumulation of cell wall pectins within intracellular BFA compartments. Importantly, cold treatment and protoplasting prevented internalization of wall pectins into root cells upon BFA treatment. These observations suggest that cell wall pectins of meristematic maize root cells undergo rapid endocytosis in an F-actin-dependent manner.]]> Sat 24 Mar 2018 08:28:12 AEDT ]]> Small molecules demonstrate the role of dynamin as a bi-directional regulator of the exocytosis fusion pore and vesicle release https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:28297 Sat 24 Mar 2018 07:33:49 AEDT ]]> Dynamin regulates specific membrane fusion events necessary for acrosomal exocytosis in mouse spermatozoa https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:22263 in vitro induction of acrosomal exocytosis by progesterone, but not by the calcium ionophore A23187, and elicited a concomitant reduction of in vitro fertilization. In vivo treatment with these inhibitors also resulted in spermatozoa displaying reduced acrosome reaction potential. Dynamin 1 and 2 phosphorylation increased on progesterone treatment, and this was also selectively blocked by dynasore. On the basis of our collective data, we propose that dynamin could regulate specific membrane fusion events necessary for acrosomal exocytosis in mouse spermatozoa.]]> Sat 24 Mar 2018 07:17:38 AEDT ]]> ACh-induced hyperpolarization and decreased resistance in mammalian type II vestibular hair cells https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:35648 -/-) mice. Immunostaining for choline acetyltransferase revealed there were no obvious gross morphological differences in the peripheral EVS innervation among any of these strains. ACh application onto wt type II hair cells, at resting potentials, produced a fast inward current followed by a slower outward current, resulting in membrane hyperpolarization and decreased membrane resistance. Hyperpolarization and decreased resistance were due to gating of SK channels. Consistent with activation of a9*nAChRs and SK channels, these ACh-sensitive currents were antagonized by the a9*nAChR blocker strychnine and SK blockers apamin and tamapin. Type II hair cells from a9-/- mice, however, failed to respond to ACh at all. These results confirm the critical importance of a9nAChRs in efferent modulation of mammalian type II vestibular hair cells. Application of exogenous ACh reduces electrical impedance, thereby decreasing type II hair cell sensitivity. NEW & NOTEWORTHY Expression of a9 nicotinic subunit was crucial for fast cholinergic modulation of mammalian vestibular type II hair cells. These findings show a multifaceted efferent mechanism for altering hair cell membrane potential and decreasing membrane resistance that should reduce sensitivity to hair bundle displacements.]]> Fri 18 Aug 2023 10:20:28 AEST ]]>