SNSS

  Lectures

※Alphabetical order

Speaker
Dr. Pablo A. Iglesias (The Johns Hopkins University)

Title
Theoretical and Experimental Analysis of Chemotactic
Systems in Biology

Abstract
Many biological systems have the ability to sense the direction of external chemical sources and respond by polarizing and migrating toward chemoattractants or away from chemorepellants. This phenomenon, referred
to as chemotaxis, is crucial for proper functioning of single cell organisms, such as bacteria and amoebae, as well as multi-cellular systems as complex as the immune and nervous systems. Chemotaxis also appears to be important in wound healing and tumor metastasis.
I will discuss our groups efforts at elucidating the mechanisms underlying chemotaxis. Using known biochemical data, we have developed mathematical models that can account for many of the observed
chemotactic behavior of the model organism Dictyostelium. I will discuss experiments used to test these models. Finally, I will describe how information-theoretic methods can be used to evaluate the optimality of the gradient sensing mechanisms.

References
* Levchenko A, Iglesias PA: *Models of eukaryotic gradient sensing: application to chemotaxis of amoebae and neutrophils*.     /Biophys J /2002, *82*:50-63.

* Janetopoulos C, Ma L, Devreotes PN, Iglesias PA: *Chemoattractant-induced phosphatidylinositol 3,4,5-trisphosphate accumulation is spatially amplified and adapts, independent of the actin cytoskeleton*. /Proc Natl Acad Sci U S A /2004, *101*:8951-8956.
   
* Ma L, Janetopoulos C, Yang L, Devreotes PN, Iglesias PA: *Two complementary, local excitation, global inhibition mechanisms acting in parallel can explain the chemoattractant-induced regulation of PI(3,4,5)P3 response in dictyostelium cells*.  /Biophys J /2004, *87*:3764-3774.

* Franca-Koh J, Kamimura Y, Devreotes P: *Navigating signaling networks: chemotaxis in Dictyostelium discoideum*. /Curr Opin Genet Dev /2006, *16*:333-338.


Speaker
Dr. Mineko Kengaku (RIKEN)

Title
Mechanisms of neuronal migration

Abstract
Newborn neurons in the developing brain migrate from the site of birth to their destination for integration into specific neural circuits.  Neuronal migration is highly directional movement along either radial or tangential dimension of the cylindrical neural tube.  Migrating neurons polarize to extend the leading process in the direction of the travel, and then translocate the cell body containing the nucleus into the leading process.  In this lecture, we will discuss the molecular and cellular dynamics of neuronal migration in comparison with other cell types. 

References

Speaker
Dr. Ikue Mori (Nagoya University)

Title
Molecular and physiological basis of learning and memory in the neural circuit of behavior

Abstract
The behavioral response of C. elegans to temperature called thermtaxis is an ideal system for elucidation of the mechanism by which animals sense temperature and memorize temperature. The neural circuit essential for this thermotaxis behavior was identified and several genes required for thermotaxis were isolated. Thermotaxis was further shown to be the behavioral outcome of associative learning between temperature and feeding state. To address how genes acting in the neural circuitry generate behavior, the activities of the component neurons in the thermotaxis neural circuit in live animals were monitored using a genetically encodable calcium sensor. Systematic optical imaging of neurons in the thermotaxis circuit combined with application of computational biology may ultimately propose a new concept for dynamics of neural circuit controlling behavior.
References

Speaker
Dr. Akinao Nose (The
University of Tokyo)

Title
Watching and dissecting selective synapse formation

Abstract
The proper functioning of the nervous system depends on precise interconnections of distinct types of neurons.  Therefore, understanding the molecular mechanisms of synaptic specificity ― the specificity with which connections form between neurons ― is a central issue in modern neuroscience.  We have used the Drosophila neuromuscular system to study this problem.  In this lecture, I will talk about the following two new developments.  (1) Using microarray, we identified Wnt4 as a repulsive target cue.  Our results showed that target specificity is determined not only by an attractive signal from the target cell but also by a negative signal from neighboring non-target cells (ref.2), (2) live-imaging analysis of the process of synapse formation revealed in vivo role of a cell adhesion molecule in synaptic induction (ref.3).

References

Speaker
Dr. Alex Reyes (New York University)

Title
Experimental And Theoretical Analyses Of Circuitry Underlying Neuronal Firing In Cortex

Abstract
The responses of cortical neurons in response to sensory stimulation are diverse. The goal of this study is to elucidate the cellular properties and network architecture that underlie the firing behaviors of cortical neurons.  We first perform multiple whole-cell recordings in a slice preparation to characterize the synaptic and intrinsic
membrane properties of pyramidal cells and interneurons as well as their patterns of connections.  We then use the measured parameters to perform simulations both in vitro and with a computer to determine salient firing behaviors that arise from the network. Surprisingly, we were able to account for many of the firing behaviors and receptive field properties of cortical neurons with a simple network of pyramidal and inhibitory neurons. Finally,  we use mean field theoretical techniques borrowed from Physics to elucidate general principles that are applicable to the nervous system as a whole.

References

Speaker
Dr. Peter J Verveer (Max Planck Institute of Molecular Physiology)

Title
Functional imaging of molecular processes in living cells

Abstract
In the last few decades, fluorescence microscopy has become a vertasile and indispensable tool for investigating molecular processes in living cells. It has become possible to measure the localization, activity and interactions of proteins in single living cells with high spatial and temporal resolution. In the first part of this lecture, the basics of fluorescence and of fluorescent labeling in cells will be discussed. In the second part the basics of fluorescence microscopy will be described, and recent developments in the field will be presented. In the last part, methods for measuring protein activity and interactions in living cells using fluorescence microscopy will be presented.

References
E. Haustein and P. Schwille. Fluorescence correlation spectroscopy: novel variations of an established technique. Annu. Rev. Biophys. Biomol. Struct. 36: 151-169, 2007.

S. W. Hell. Far-field optical nanoscopy. Science 316:1153-1158, 2007.

E. A. Jares-Erijman and T. M. Jovin. Imaging molecular interactions in living cells by FRET microscopy. Curr. Opin. Chem. Biol. 10:409-416, 2006.

J. Lippincott-Schwartz and G. H. Patterson. Development and use of fluorescent protein markers in living cells. Science 300:87-91, 2003.

F. S. Wouters, P. J. Verveer and P. I. H. Bastiaens. Imaging biochemistry inside cells. Trends Cell Biol. 11:203-211, 2001.