לוח שנה משולב

The process of self-replication is at the core of Biological systems. Therefore, understanding the constraints that act on the process of self-replication is crucial. However, little is known about the physical and evolutionary constraints that shape the observed behavior of Biological Systems. We show that molecular noise can be exploited by bacteria to spread the time-scale of self-replication. However noise is not always the underlying cause of variability in clonal cells populations. We show that the variability of self-replication times in mammalian cells is governed by a deterministic process.

Displacement studies have clearly showed that birds are able to perform true navigation, i.e. they can find direction leading to destination from unfamiliar territory. Yet, the sensory mechanisms of navigation remain poorly understood. There are two primary hypotheses explaining the sensory nature of navigation: (1) a magnetic map hypothesis proposes that birds use parameters of the geomagnetic field which predictably distributed on the globe. This hypothesis claims that the magnetic receptor cells used for navigation reside in the upper beak (the so-called ‘beak organ’), and transmit information via the trigeminal nerve to the brain; (2) an olfactory map hypothesis assumes that birds can use olfaction and smell their position by taking advantage of odours predictably distributed in the atmosphere. In the last decade, I together with my co-workers have experimentally tested both hypotheses in migratory songbird species by combining sensory manipulations with displacements both in Europe and North America. Specifically, in our main model species, Eurasian reed warblers (Acrocephalus scirpaceus), a long-distance nocturnal migrant, we have found that this species (and maybe other songbird migrants) use geomagnetic cues and the magnetoreceptors embedded in the trigeminal system for geographical positioning. In parallel with our studies, there is a growing support for olfactory long-distance navigation in sea birds and homing pigeons. In my talk, I will overview the challenges of understanding true navigation in birds and present the most important advances in the context of other relevant studies.