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UID:1676386800@ist.ac.at
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DESCRIPTION:Speaker: Kohgaku Eguchi and Roshan Satapathy\nAbstract: Speaker
 : Koghaku Eguchi (Postdoc\, Shigemoto group)Title: Alternative splicing 
 of CaV2.1-EF-hand regulates coupling between calcium influx-synaptic vesic
 le exocytosisAbstractTight coupling between voltage-gated calcium channels
  (VGCCs) and the sensors of neurotransmitter release is crucial for fast a
 nd efficient synaptic transmission. At parallel fiber (PF)-Purkinje cell (
 PC) synapses in mouse cerebellum\, the coupling tightens during synaptic m
 aturation in parallel with a switching of expression from EFb to EFa splic
 ing isoforms of the P/Q-type VGCC (Cav2.1) EF-hand. In hippocampal pyramid
 al neurons\, the Cav2.1[EFa] isoform has been reported to exhibit the high
 er synaptic efficacy than the Cav2.1[EFb] isoform. Thus\, the transition o
 f the Cav2.1-EF hand isoforms may play a causal role in tightening the cou
 pling at PF synapses. To address this hypothesis\, we generated a knock-in
  mice expressing only Cav2.1[EFb] in a Cre-dependent manner and crossed th
 em with E3CreN driver mice expressing Cre selectively in cerebellar granul
 e cells. We then used electrophysiology and SDS-digested freeze-fracture r
 eplica labeling to compare the coupling distance at PF-PC synapses in thes
 e mice (EFb mice) and wild-type (WT) mice\, which predominantly express th
 e EFa variant. A slow Ca2+ chelator EGTA attenuated neurotransmitter rele
 ase stronger\, indicating a looser coupling\, in EFb than in WT mice. Dire
 ct measurement of the distance between gold particles for Cav2.1 and vesic
 le docking site marker proteins in replica samples showed significantly lo
 nger nearest neighbor distances at the active zone in EFb than WT mice\, s
 upporting the results of the electrophysiological results. These results s
 uggest that the splicing transition of the Cav2.1-EF hand at PF synapses i
 nduces a developmental tightening of Ca2+ influx-release coupling. Speak
 er: Roshan Satapathy (PhD. Jösch group)Title: Estimation of self-moti
 on in insects is mediated by interaction between LPTCsAbstract :Animals re
 ly on visual cues to compute self-motion for course stabilization. In flie
 s\, self-motion is estimated primarily by a network of optic flow-sensitiv
 e neurons called lobula plate tangential cells (LPTCs). While these neuron
 s have been characterized in great detail\, the mechanism by which their o
 utputs are transformed into specific motor commands for course control is 
 largely unknown. We hypothesize that interaction and exchange of informati
 on between LPTCs is essential for the correct interpretation of optic flow
  and subsequent generation of stabilizing responses. In this talk\, I will
  present two complementary approaches that we developed for studying these
  interactions.First\, we generated a FlpStop based genetic cassette to dis
 rupt gap junctions between LPTCs in order to explore the role of electrica
 l coupling in the network. Using this newly generated mutant\, we show tha
 t estimation of self-motion requires binocular integration of visual infor
 mation mediated largely via gap junctions. Second\, we developed a genetic
  technique\, based on SPARC\, for stochastic excitation and inhibition of 
 different subset of LPTCs. By mapping behavioral responses to correspondin
 g patterns of excitation and inhibition\, we are able to construct the beh
 avioral repertoire of the LPTC network. Overall our results establish the 
 importance of electrical coupling in the motion vision system of insects a
 nd shed light on the behavioral role of LPTCs
LOCATION:Mondi 2\, ISTA
ORGANIZER:mariam.mosiashvili@ist.ac.at
SUMMARY:Kohgaku Eguchi and Roshan Satapathy: Kohgaku Eguchi and Roshan Sata
 pathy
URL:https://talks-calendar.ista.ac.at/events/3992
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