Pr

1
Alain Ghysen - Montpellier
involved in - predator avoidance - prey
detection - swimming in schools - rheotaxis
(swim against current) - sexual behaviour -
building map of external world - and probably
more
The lateral-line system comprises a large set of
individual organs, the neuromasts, distributed
over the head and body in species-specific
patterns
2
Various methods to detect neuromasts in zebrafish
neuromast cellular organization
hair cells
support cells
mantle cells
skin
neurons
will they all work in tunafish embryos larvae?
3
Many different patterns in adult fish
what is the pattern in adult zebrafish?
4
complicated pattern with several hundreds of
neuromasts (marked with Di Asp, every white dot
is a neuromast)
Danio ostariophysian, basal group Psetta
acanthopterygian, highly derived group diverged
about 150 million years ago gt embryonic
patterns are highly conserved even though adult
patterns very different (so highly conserved
that the tunafish embryonic pattern is likely to
be the same - verify)
How is the embryonic pattern formed? understood
only in zebrafish
5
(optional simplified phylogeny)
6
The embryonic pattern is laid down by a migrating
group of cells (migrating primordium). This
primordium deposits five groups of cells, each of
which will become a neuromast
primordium migration
(unrelated to SELFDOTT, but interesting anyway
the molecular machinery that underlies
primordium migration is exactly the same as that
which underlies cell migration and the formation
of metastases in many human cancers)
7
Transition from embryonic (highly conserved) to
adult (highly divergent) pattern? in Danio
1. Formation of a second lateral line (in blue)
with a lateral and a dorsal branch
2. Formation of intercalary neuromasts between L1
- L5
nothing is known about post-embryonic development
in any other fish species
8
Potential interest for SELFDOTT in zebrafish,
the post-embryonic growth of the PLL system has
a very reproducible dynamics
Number of post-embryonic neuromasts
gt a very simple and sensitive way to measure
growth?
9

• Project
• develop tools to visualize neuromasts at
  different developmental stages
• verify that the "standard" embryonic pattern is
  conserved in BFT
• explore the onset of post-embryonic development
• establish the dynamics of neuromast addition
  (to validate PLL as a quantitative indicator
  of development)
• Brain projections I will introduce this aspect
  next year as there is no way I could do this in
  the 10min period that is allowed to me by Denis
  Coves