126 spine answers

126 spine answers - It is studied by tagging PSD-95 with...

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Problem set 6 (10 points) Questions on the papers by Gray et al., due Tuesday 3/3/09 at the start of class: 1) (3 points) What method the authors use to selectively label layer2/3 neurons? Two DNA constructs were injected at the same time, what are they and what structures do they label? In utero electroporation. (1pt) mCherry labels the whole neuron. (1pt) PSD-95-GFP labels only the dendritic spine (can also say: only the post-synaptic site). (1pt) 2) (3 points) Why are authors interested in synaptic PSD-95 stability? How was PSD-95 stability studied in this paper? PSD-95 is the major postsynaptic scaffold protein. It binds to NMDAR and interacts with AMPAR. PSD-95 level may determine synaptic strength. (give 1pt when any of these is mentioned, as long as the answer links PSD-95 and synaptic plasticity)
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Unformatted text preview: It is studied by tagging PSD-95 with photoactivatable GFP (paGFP), then use two-photon laser excitation to irreversibly converte the dark paGFP into bright fluorophores, and then flow the decay time from the single spine. (2pt) 3) (4 points) What is fluorescence retention time mentioned in this paper? How does the PSD size over time predict changes in retention time? How do the retention times change with developmental age and sensory deprivation? Retention time: the apparent time constant for the exponential component of the fluorescence decay. (1pt) Bigger spines have longer retention time. (1pt) Retention time increase with developmental age (1pt) and decrease with sensory deprivation (1pt)...
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