Ivan Anastassov

The overall goal of my research program is to understand how neuronal cell type diversity within sensory tissues contributes to circuit formation and allows sensory systems to process complex stimuli. Establishing the right connections between neurons is a fundamental requirement for sensory systems, as sensory input is often conveyed to the brain through a vast diversity of neuronal cell types making selective connections within the network. What is the underlying function of this neuronal diversity? Does each subtype of sensory neuron make connections with the right partners in a genetically predetermined way, or are those connections based on the sensory input to the system?

One sensory tissue in which we can address these questions is the retina. The retina is a nervous tissue that lines the back of your eye. What the eye sees is complex – each image received by the retina is a combination of features like outline, contrast, color, motion and direction, among others. That is a lot to take, so in most vertebrate retinas, effective processing of visual information is achieved by splitting different aspects of the visual stimulus into separate tracks called ‘parallel pathways’. This is where neuronal diversity comes into play – different retinal cell types tend to handle only specific aspects of a visual stimulus using a kind of “divide and conquer” strategy. But how does this happen? Is selectivity for color or contrast a property of the neuron’s shape, or the type of input it receives, or its unique set of membrane receptors, or a combination of all of these factors? Furthermore, are these characteristics immutable, or a product of the cell’s early experience and surrounding synaptic contacts?

We address these broad questions in retinal cell biology and circuit function in the retinas of mice and skates (a type of cartilaginous fish closely related to sharks) by using a combination of molecular, anatomical and neurophysiological approaches.

Fall 2024:BIOL 350 Cell Biology and  BIOL 640 Cellular Neuroscience

• Magaña-Hernández, L., Wagh, A. S., Fathi, J. G., Robles, J. E., Rubio, B., Yusuf, Y., Rose, E. E., Brown, D. E., Perry, P. E., Hamada, E., & Anastassov, I. A. (2023). Ultrastructural characteristics and synaptic connectivity of photoreceptors in the simplex retina of Little skate (Leucoraja erinacea). ENeuro, 10(October), ENEURO.0226-23.2023. https://doi.org/10.1523/ENEURO.0226-23.2023

• Shen, H., Anastassov I.A., Kreitzer, M.A., Slaughter, M.M., Chappell, R.L. (2021) A dark decrement for enhanced dynamic sensitivity of retinal photoreceptors. Vision Research, In Press
• Care R.A., Anastassov I.A., Santina L.D., Kastner D.B.  Kuo YM., Dunn F.A. (2020) Mature retina compensates functionally for partial loss of rod photoreceptors. Cell Reports, 31, 107730
• Anastassov, I.A., Wang, W., Dunn, F.A. (2019) Synaptogenesis and synaptic protein localization in the postnatal development of rod bipolar cell dendrites in mouse retina. Journal of Comparative Neurology 527 (1):52-66
• Agosto M.A., Anastassov, I.A., Robichaux, MA, Wensel, T.G. (2018) A large endoplasmic reticulum-resident pool of TRPM1 in retinal ON bipolar cells. eNeuro Jul 4; 5(3).
• Agosto, M.A., Anastassov, I.A., Wensel TG. (2018) Differential epitope masking reveals synapse-specific complexes of TRPM1. Visual Neuroscience 35: E001.
• Eblimit A., Akshay S., Thomas K., Anastassov I.A., Abulikemu T, Mardon G, Chen R. (2017) Conditional loss of Spata7 in photoreceptors causes progressive retinal degeneration in mice. Experimental Eye Research 166:120–130.
• Wensel, T.G., Zhang, Z., Anastassov, I.A., Gilliam, J. He, F., Schmid, M.F., Robichaux, M.A. (2016) Structural and molecular bases of rod photoreceptor morphogenesis and disease. Progress in Retinal and Eye Research (55): 32-51
• He, F., Agosto, M.A., Anastassov, I.A., Tse, D., Wu, S., Wensel, T.G. (2016) Phosphatidylinositol-3-phosphate is light-regulated and essential for survival in retinal rods. Scientific Reports 6, 26978
• Agosto, M.A., Zhang, Z., He, F., Anastassov, I.A., Wright, S.J., McGehee, J., Wensel, T.G. (2014) Oligomeric state of purified transient receptor potential melastatin-1 (TRPM1), a protein essential for dim light vision. Journal of Biological Chemistry289(39): 27019-33
• Anastassov, I., Ripps, H., Chappell, R.L. (2014) Cytoprotection by endogenous zinc in the vertebrate retina. Journal of Neurochemistry 129(2): 249-55
• Anastassov, I., Shen, W., Ripps, H., Chappell, R.L. (2013) Zinc modulation of calcium activity at the photoreceptor terminal: A calcium imaging study.  Experimental Eye Research 112: 37-44
• Chappell, R.L., Anastassov, I., Lugo, P., & Ripps, H. (2008). Zinc-mediated feedback at the synaptic terminals of vertebrate photoreceptors. Experimental Eye Research, 87(4), 394–7.
• Lee, K.-G., Miller, T., Anastassov, I., & Cohen, W.D. (2004). Shape transformation and cytoskeletal reorganization in activated non-mammalian thrombocytes. Cell Biology International, 28(4), 299–310.