Lecturer: Prof. Joel Stavans
Affiliation: Faculty of Physics,
Weizmann Institute of Science
Abstract:
Under prolonged nitrogen deprivation,
one-dimensional filaments of the
multicellular organism Anabaena undergo
a process of development, forming a
pattern consisting of single cells
specialized for nitrogen fixation, separated
by a chain of about ten photosynthetic,
vegetative cells. The developmental
program uses activation, inhibition, and
transport to create spatial and temporal
patterns of gene expression, in the
presence of unavoidable, coupled
stochastic fluctuations in gene expression
among cells. Using a chromosomal
fluorescent marker, we followed the
expression of an important regulator in
individual cells along filaments, both under
abundant nitrogen conditions as well as at
different times after nitrogen deprivation.
The results of our statistical analysis of
these fluctuations illuminate the
fundamental role that positive feedback,
lateral inhibition and cell-cell
communication play in the developmental
program, and establish the spatial extent
to which gene expression is correlated
along filaments.