לוח שנה משולב

Biological dispersal---the movement of organisms between habitats---is a
ubiquitous phenomenon with important and wide-ranging consequences. In the
natural environment, organisms expand their ranges, colonise new habitats,
and can undergo speciation if they become spatially isolated. Therefore,
dispersal plays a key role in determining spatial and temporal patterns of
genetic diversity. It has been pointed out recently, that migration from a
favourable habitat to an unfavourable one can explain the genetics of some
pathogenic microbes and viruses. However, despite its importance, a general
understanding of how migration affects mutation-selection balance in
microbial systems is lacking. In particular, one would like to know how
migration changes the proportions of different genotypes in the evolving
population. Here I will discuss a simple model for evolution of asexual
organisms in two different habitats, with different fitness landscapes,
coupled through one-way migration. The key finding is a dynamical phase
transition at a critical value of the migration rate. The time to reach
steady state diverges at this critical migration rate. Above the transition,
the population is dominated by immigrants from the primary habitat. Below
the transition, the genetic composition of the population is highly
non-trivial, with multiple coexisting quasi-species which are not native to
either habitat. Using results from localization theory, I will show that the
critical migration rate may be very small --- demonstrating that
evolutionary outcomes can be very sensitive to even a small amount of
migration.

Just as the original open source software was propelled by software developers motivated to contribute to large collaborative projects, proponents of Open Source Drug Discovery (OSDD) believe that the global need for new low-cost drugs, particularly for treating neglected tropical diseases, will make this model effective. Because drug research is so complex, different OSDD initiatives are applying different strategies. For example, under Brahmachari’s direction, India launched an OSDD program in 2008, aimed to have a web-enabled interactive open source platform listing the current design challenges for developing drugs to treat diseases such as tuberculosis, malaria, and HIV. Research teams from CSIR and other government, university and industry participants contribute to the posted drug design challenges. This may include new algorithm or information about a new drug target. As first steps, the CSIR’s OSDD initiative has launched an open source website hosting information about Mycobacterium tuberculosis, including gene sequences, expression, function, activity, and the response to drugs of all M. tuberculosis proteins as well as host-pathogen interactions
(http://mtbsysborg.igib.res.in). As the next step, CSIR will initiates an open source program for malaria, with global participation. (see S. Singh, Cell 113:201-3 (2008)

Professor Brahmachariis Secretary to the Department of Scientific and Industrial Research (DSIR), Ministry of Science and Technology, Government of India and Director General of Council of Scientific and Industrial Research (CSIR), India.

The hypothalamo-neurohypophyseal system (HNS) is a central point of interface between the hormonal, neuronal and vascular systems and constitutes a conduit through which the brain exerts control over peripheral organs. The neuropeptides arginine-vasopressin (AVP) and oxytocin (OXT), highly conserved in all vertebrates, are produced in hypothalamic neurons and released from their axons onto fenestrated capillaries in the neurohypophysis, where they enter the general circulation. To identify signaling events controlling neurohypopheseal development, we have generated a transgenic OXT reporter zebrafish line in which oxytocinergic neurons and their axonal termini are fluorescently labeled, and used it to trace the organization of the HNS during embryogenesis and characterize the interactions between OXT neurosecretory termini and the developing hypophyseal vasculature. Using this newly established experimental system, we show that OXT signaling is required for formation of the hypophyseal vasculature, leading us to hypothesize that it is acting as an angiogenic signal during HNS morphogenesis.