BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Evolving mechanisms of Pattern Generation: Segmentation in Animals
  - Professor Michael Akam (Laboratory for Development and Evolution\, Depa
 rtment of Zoology\, Cambridge)
DTSTART:20061117T151500Z
DTEND:20061117T154500Z
UID:TALK5269@talks.cam.ac.uk
CONTACT:Duncan Simpson
DESCRIPTION:Many of the most successful animal groups are based on modular
  design.  The body is made of a series of repeating units\, or segments\, 
 that are modified to a greater or lesser extent to serve distinct function
 s.  In vertebrates\,  modular organisation is most apparent early in devel
 opment\, but a reflection of this fundamental segmentation persists in the
  adult vertebral column and nervous system.\n\nThe gene networks that gene
 rate segments are particularly well understood in the fruit fly Drosophila
 .  Here\, segmentation is divorced from growth.  All segments of the body 
 are generated simultaneously\, by a cascade of gene regulatory interaction
 s operating within the egg while it is still a single\, large\, multinucle
 ate cell. \n\nSegmentation in vertebrates appears to use quite different m
 echanisms\, involving temporal and spatial oscillations of gene expression
  within a growing population of cells. These oscillations are co-ordinated
  by cell-cell interactions.  The oscillating pattern of gene expression be
 comes  “frozen” at a moving wavefront  in the embryo to generate a sta
 ble pattern of alternating cell states that underlies segmentation.  Segme
 nts thus appear sequentially\, from head to tail\, as the embryo grows.\n\
 nRecent work has made it clear that much of the Drosophila segmentation ca
 scade is a relatively new invention that evolved within the arthropods\, p
 robably as an adaptation to speed up development.  Other arthropods\, for 
 example centipedes\, use mechanisms that may be more similar to those foun
 d in vertebrates than they are to the highly derived mechanism seen in Dro
 sophila.  Our own research seeks to understand what were the ancestral mec
 hanisms of segmentation within the arthropods\, and how these evolved into
  the gene regulatory cascade that we know from Drosophila.\n
LOCATION:Kaetsu Centre\, New Hall
END:VEVENT
END:VCALENDAR