Previous Research
Post Graduate Researcher
Cultured Amacrine Cell Receptor Spacing
Using images taken by Dave Dalcino, a former member of the Wilson Lab, I collected a set of spacing intervals for each type of receptor and a nearest-neighbor set for ryanodine receptors and their nearest IP3 companion.
Following the data collection, randomized samples were created to test our hypothesis: receptors appear in a nonrandom distribution along a dendrite.
Two factors caused us to formulate this hypothesis:
- Both receptors are thought to span the same type of membrane.
- Both receptors are Ca2+ ion transport channels.
Immunohistochemically stained dendrite
A very narrow amacrine cell dendrite, showing the distribution of IP3Rs (green) and RyRs (red). Primary antibodies were against a synthetic C-terminal peptide of Type 1 IP3R and chicken skeletal muscle and RyRs.
The data for a typical dendrite are plotted as filled circles (IP3Rs in green, RyRs in red) in the figure below. Filled black circles represent the nearest-neighbor distribution from RyRs to IP3Rs, since fewer RyRs were present.
The lines in the figure show a randomly generated logarithmically-normal CRF distribution. The black curve is the CRF distribution generated by a simulated random shuffling of the positions of the RyRs along each dendrite and recomputation of the nearest-neighbor data. This distribution is totalled from 500 repeat shufflings.
Comparison of real and random spacing distributions
Cumulative IP3R and RyR spacing distributions fit to log-normal cumulative probability distributions. Receptor distributions are taken from one specific dendrite.
Our data suggest that our hypothesis was incorrect.
RyRs and IP3Rs appear to have no explicit spatial relationship. In other words, the position of one RyR does not seem to have any connection to the position of the nearest neighboring IP3R. Also, the individual receptors appear not to have any grouping behavior amongst their own type, within the limit of our microscope's resolution.
