EXRC supports cell and developmental biologists who use the

Xenopus model. It provides wild-type, transgenic and mutant frogs

to research labs at cost and can now also supply oocytes, embryos

and frozen sperm. All of the GA animals are quality controlled to

ensure that their offspring have the expected phenotype. In addi-

tion to these animal resources EXRC is gathering insitu hybridisa-

tion probes, relevant antibodies and expression clones from labs;

again these are being quality controlled and then made available

to researchers at cost. EXRC also has Xenopus tropicalis fosmid

libraries available and full length Xenopus laevis ESTs.

In terms of research for the community EXRC has undertaken

a large survey of chytrid (Bd) infection of the UK Xenopus colonies

and is refining transgenesis techniques. Our main aim in this area

currently is to identify transgenic lines that the cell and develop-

mental biology communities require and to produce these at

medium throughput.

doi:10.1016/j.mod.2009.06.1221

22-P011 Comparative analysis of early axon tracts in the

embryonic vertebrate brain

Michelle Ware, Frank Schubert

University of Portsmouth, Portsmouth, United Kingdom

Initial nerve connections in the vertebrate brain form an array

of longitudinal tracts, transversal tracts and commissures, which

acts as a scaffold for later, follower axons that allow more complex

connections to occur in the brain. For correct development of the

early axon scaffold, neurones are specified to their specific fate

by homeobox genes such as Sax1, Emx2, Six3, Pax6 and Nkx2.2 at

the correct place and time. The early axon scaffold has been iden-

tified in a number of vertebrates, and many of the tracts appear

remarkably conserved between all vertebrates analysed. However,

a direct comparison of early tracts between different species is

lacking, and many of the tracts are poorly characterised. To analyse

the early axon scaffold and provide a comparative description, the

early neurons and their tracts can be mapped using pan-neural

antibodies in embryonic vertebrate brains. The first time series of

axon tracts has been analysed in chick embryos using Tuj1 anti-

body and also combined with DiI labelling to demonstrate the for-

mation of neurones and tracts in the early axon scaffold. The MLF

is the first axon tract to form in the embryonic brain as previously

shown, but its neurones appear at HH11, earlier than previously

suggested. Zebrafish, Xenopus, catshark and mouse embryos have

also been labelled with a range of antibodies to describe the forma-

tion of the early axon scaffold with the aim of completing a time

series and finding a comparative antibody. This will also provide

insight into the evolution of the embryonic brain architecture.

doi:10.1016/j.mod.2009.06.1222

22-P012 The role of Aminopeptidase O (ApO) in vascular biology

and disease

Richard Axton, Helen Taylor, Julie Wilson, Lesley Forrester

MRC Centre for Regenerative Medicine, University of Edinburgh,

Edinburgh, United Kingdom

The acquisition of a new blood vessel supply (angiogenesis)

plays a significant role in the progression of many diseases

including solid tumour growth, rheumatoid arthritis and athero-

sclerosis. Implicit in the progression of these diseases is the

altered regulation of proteases that are either able to degrade

extracellular matrix or control cell cycle.

We identified a gene trap integration into Aminopeptidase O, a

member of the M1 family metalloaminopeptidases. Using the

bgal reporter of the gene trap vector, we have revealed that ApO

isoforms are expressed predominantly in embryonic and adult

blood vessels. SiRNA knockdown of APO in Human Umbilical Vein

Endothelial Cells resulted in an angiogenic phenotype in a Mati-

gel capillary tube formation assay. We propose that this protease

is important in the process of angiogenesis and may be a poten-

tial therapeutic target for anti cancer drug discovery.

The full length GFP-APO fusion protein localised to the

nucleolus in transfected COS7 cells. We identified a putative

nucleolar localisation signal, which when removed from the pro-

tein resulted with APO being retained in the cytoplasm. We

report the existence of multiple alternatively-spliced ApO iso-

forms that differ with respect to the presence of exons encoding

important functional domains. Alternative splicing predictably

produces protein products with or without the catalytic domain

and/or a nucleolar localisation signal and therefore likely repre-

sents an important mechanism in regulating the biological

activity of APO.

doi:10.1016/j.mod.2009.06.1223

22-P013 – Withdrawn

22-P014 Molecular correlates of life history trade-offs

Sarah Morgan1,3, Peter Dearden1,3, David Raubenheimer2,3

1University of Otago, Dunedin, New Zealand2Massey University Albany, Auckland, New Zealand3National Research Centre for Growth & Development, Auckland, New

Zealand

The life history trade-off between longevity and reproduc-

tion is seen in a variety of animals. It has been found in the

model organism Drosophila melanogaster that regulation of life-

span and reproduction rates are linked with various ratios of

protein to carbohydrate diet ingested by the flies throughout

their lifetime.

Dietary Restriction and its effects on lifespan have been stud-

ied for many years, with consistent results seen between vastly

different organisms. Restriction of caloric intake is known to

extend lifespan in these different organisms. Initially called Calo-

ric Restriction, it has been shown in Drosophila that isocaloric

diets of yeast (as a protein source) and sugar, in varying ratios,

results in organisms portraying the typical trade-off between life-

span and reproduction, implying that it is macronutrient status

rather than Caloric Restriction that is extending lifespan. Isocalo-

ric is the term used to describe diets of differing component

ratios, while maintaining the same calorie value. When given

S332 M E C H A N I S M S O F D E V E L O P M E N T 1 2 6 ( 2 0 0 9 ) S 3 2 9 – S 3 3 5