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The lateral-line system comprises a large set of individual organs, the neuromasts,

the lateral line: a sensory system of utmost importance provides a sense of "touch at a distance" (touch without touching ). Alain Ghysen - Montpellier. involved in:

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The lateral-line system comprises a large set of individual organs, the neuromasts,

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  1. the lateral line: a sensory system of utmost importanceprovides a sense of "touch at a distance" (touch without touching) 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. Nomarski optics tuft of hairs round nuclei of hair cells elongated nuclei of mantle cells DiAsp (fluorescent dye specifically taken up by functional hair cells, works only on living fish) Alc. Phosphatase (reveals the polarity of the neuromast, works on fixed fish) 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. In the embryo: much simpler pattern 5 neuromasts on each side of the body Psetta maxima (turbot) embryo: almost identical to zebrafish 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 => 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 migration pathway of the primordium 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. L1 L2 L3 L4 L5 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 => 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

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