03-P070 A YFP-exon trap screen to identify patterns of gene expression and protein localisation in Drosophila embryos

MECHANISMS OF DEVELOPMENT

mechanical strain on gene cascades in developing bone would impact efforts in tissue engineering of skeletal tissues.

1 2 6 ( 2 0 0 9 ) S 6 7 –S 1 0 6

S87

the sub-cellular localisation patterns of almost every protein. In Drosophila, a few hundred proteins have been GFP-tagged, out of about 14,000 genes. To increase the proportion of proteins

doi:10.1016/j.mod.2009.06.121

tagged in Drosophila, a UK consortium (led by D. St. Johnston and S. Russell) is generating novel exon-trap lines using piggyBac transposition to mobilize a YFP exon. The artificial exon also harbors affinity tags to identify protein partners by mass

03-P069 Development of the oculomotor system and modelling Duane’s syndrome in zebrafish Christopher Clark, Martin Meyer, Sarah Guthrie

spectrometry. In a collaborative effort with 30 other UK laboratories, we are characterising the expression and sub-cellular localisation of the YFP-tagged proteins and annotating the data using a web-inter-

MRC Centre for Developmental Neurobiology, King’s College London,

faced database (FlAnnotator). We have examined 346 lines so

London, United Kingdom

far and characterised the localisation of the tagged proteins in the cellularising embryo (stage 5), as well as documenting expres-

Eye movements in vertebrates are controlled by six extraocu-

sion levels and patterns during mid- (stage 11) and late- (stages

lar muscles innervated by three of the cranial nerves – the ocu-

15–17) embryogenesis. We found that out of 242 tagged proteins

lomotor, trochlear and abducens. Incorrect development of this

expressed at cellularisation, 54% were enriched in the cytoplasm,

wiring network can lead to eye movement disorders, such as

25% in nuclei and 17% at the cell membrane (4% did not show

the congenital condition Duane retraction syndrome (DRS),

enrichment in any sub-cellular compartments). We also found

which results in squint (strabismus). In DRS patients, the abdu-

that out of 335 lines expressed during embryogenesis, 55% had

cens nerve is often absent, and the oculomotor nerve branches

tissue or organ-specific expression patterns, a common one being

to an inappropriate muscle target. How the program of neural

expression in the nervous system (18%). We are currently charac-

projections to the extraocular muscles is regulated in normal

terising the lines further to identify those that show differential

or abnormal development is mostly unknown. However, our

expression or localisation during parasegmental boundary

recent studies have identified mutations in the signalling mole-

formation.

cule alpha2-chimaerin as being causal in DRS, and have shown that mutant forms of alpha2-chimaerin lead to striking axon

doi:10.1016/j.mod.2009.06.123

guidance defects of the oculomotor nerve1. We are mapping axon projections to the extraocular muscles in normal development and Duane syndrome, using the zebrafish embryo as a

03-P071 – Withdrawn

model system. Timelapse movies of oculomotor axon guidance (using the Islet1-GFP line) show a stereotyped sequence of growth and branching to muscle targets, which differs from the pattern previously identified in the chick embryo. We are

03-P072

also using DNA injection or electroporation into oculomotor

Molecular and cellular mechanisms underlying tubulogenesis of

neurons and immunohistochemistry for nerve, muscle and/or

the notochord of Ciona intestinalis

synaptic components to precisely map the development of the

Elsa Denker, Bo Dong, Di Jiang

ocular motor system. Fluorescently-tagged alpha2-chimaerin

Unifob, University of Bergen, Bergen, Norway

constructs harbouring known human mutations will then be expressed in oculomotor and/or abducens neurons in the zebrafish in order to determine how the axon projection pattern is disrupted, using a combination of live imaging and imaging of fixed embryos.

Tubulogenesis is one of the most interesting morphogenesis processes, because it involves many fundamental cell behaviors, such as cell polarization, cell shape remodeling, and dynamic changes in cell–cell and cell–matrix adhesion and signalling. Previous studies have shown that biological tubes can be generated

doi:10.1016/j.mod.2009.06.122

through many different mechanisms, e.g. wrapping, budding, cavitation, cord hollowing, cell hollowing (Lubarsky and Krasnow, 2003). The notochord of Ciona intestinalis is a good model to study

03-P070 A YFP-exon trap screen to identify patterns of gene expression and protein localisation in Drosophila embryos Claire

Lye, David Welchman, Juliana Gutierrez Mazariegos,

Hannah Booth, Pierre-Marie Le Droguen, Valentine Battisti, Olivia Lenoir, Audrey Coiffic, Benedicte Sanson University of Cambridge, Cambridge, United Kingdom

tube formation because it is composed of only 40 cells. The way this group of mesodermal cells becomes a one-cell wide cord through convergent extension has been extensively studied. However, the later steps, leading to the formation of a tubular structure, have not been well characterized. We recently reported that this process requires the establishment of de novo apical domains as well as mesenchymal-epithelial transition leading to the formation of atypical bipolar epithelial cells (Dong et al.,

Tagging endogenous proteins with a fluorescent marker to

2009). Luminal components are concomitantly secreted and

visualise them in vivo provides a powerful method to analyse

extracellular lumen pockets form at the level of apical membrane

gene function. In yeast, this strategy was used to characterise

domain. These pockets grow and eventually fuse to form a single