Lunch @ 11:45, talk @ 12pm.

Much of complex biology results from interactions among a large number of individually simpler elements. Blood regeneration is no different. About 100 billion new blood cells are made everyday from a much smaller yet a large population of diverse stem cell population. I will present a phenomenological model of blood regeneration, which provides…

The big challenge in modern biology is to understand and control the mechanisms by which living organisms organize, maintain, remodel, and restore their shape. Some creatures are able to regenerate whole limbs or eyes, and many examples of adaptive pattern regulation tell us that understanding cell differentiation is not enough; large-scale shape…

In recent years, through parallel advances in microscopy, fluorescent probe development, and computational modeling, it has become possible to describe gene expression in a fundamentally different way: one can now directly observe single molecules of RNA in living and fixed cells using the fluorescence microscope. In this talk, I will describe…

Bacterial chemotaxis is a paradigm for how environmental signals modulate behavior. Escherichia coli, like many species of bacteria, swim by rotating a bundle of helical flagella driven by bi-directional rotary motors. Cells swim in a random pattern described as a series of swims along an approximately straight path called “runs” interrupted by…

Longevity is a remarkably plastic trait, governed by genetic programs that enable organisms to respond appropriately to environmental cues. These genetic programs are highly conserved and were first discovered in model organisms such as yeast, worms, and flies. Germline-less and daf-2 insulin/IGF-1 signaling (IIS) mutants remain youthful and…

“A quantitative phenomenological approach towards predictive biology”
Lunch at 11:45, seminar is from 12-1:00.

Pollen transcriptomics revealed the expression of of about 7.000 genes in pollen, but theoretical modelling suggests that the cooperation of all of these into the processes of wall surface and cytoplasmic volume production is a minimal condition to explain most of the morphogenic events that characterize these cells. Spatial and temporal…

“The functional contribution of synaptic complexity to learning and memory” An incredible gulf separates theoretical models of synapses, often described solely by a single scalar value denoting the size of a postsynaptic potential, from the immense complexity of molecular signaling pathways underlying real synapses. To understand the…

Catered lunch at 11:45, talk begins at 12 noon.

“Follow the wave - a dynamic mechanism for contact guidance and collective cell migration.”
Lunch @ 11:45,seminar 12-1:00

During spindle assembly, microtubules are highly enriched near chromatin by a process which, in many systems, is driven by the GTPase Ran. The Ran pathway has been proposed to establish a reaction-diffusion network that generates gradients in the behaviors of soluble proteins around chromatin, but the manner in which this happens is poorly…

Early T-cell activation is selected by evolution to discriminate a few foreign peptides rapidly from a vast excess of self-peptides, and it is unclear in quantitative terms how this is possible. It will be discussed how a generic proofreading cascade supplemented by a single negative feedback accounts quantitatively for early T-cell activation,…

During embryonic development, the forces generated by myosin II must be controlled in space and time to shape simple epithelia into tissues and organs with complex form and structure. Molecular-level properties of myosin regulation and force generation have been extensively studied in vitro, but it is not understood how these molecular properties…

Biological organisms in the real world do not typically grow up in well-mixed test tubes or featureless Petri dishes, but instead must find ways to prosper in the presence of environmental inhomogeneities that vary in space. In a collaboration with Wolfram Moebius and Andrew Murray, we have created a spatially random bacterial lawn on a Petri…

Neural networks typically make use of simplified, stereotypical single neuron units, while in reality neurons show fascinating and diverse properties that give them a range of computational and representational powers. The emerging ability that molecular techniques provide to identify, record from and manipulate the activity of different cell…

"The clonal raider ant Cerapachys biroi as a new model system for social evolution and behavior"
Lunch at 11:45, seminar at 12:00.

"A Physical Approach to Organismal Development" Understanding how the physical form of an organism emerges is a central goal of developmental biology. That said, understanding the spatio-temporal dynamics of development from a list of participating genes and molecules is difficult. Recent advances in live-imaging give us a view into organismal…

All animals sleep, or do they? This question remains controversial. If sleep is truly universal to the animal kingdom then even the simplest animal should sleep, and may offer valuable clues regarding the origin and core function of sleep (or perhaps provide insight by being an exception to the rule). The nematode Caenorhabditis elegans develops…