M A Teillet

Fabrication of microscalpels by electrolysis of tungsten wire in a meniscus.

A simple technique has been devised for generating consistent microscalpel blades from tungsten wire for use in microdissections. Electrolysis of the tungsten wire held horizontally in contact with the extended, up-lifted meniscus of an aqueous solution of 1.0 N NaOH sculps the metal into a blade configuration with a very sharp cutting edge. These microscalpels are suitable for dissection of embryonic neural tissues.

The neural crest and its developmental analysis in avian embryo chimaerast

Abstract As far as the development of the peripheral nervous system is concerned neural crest cell differentiation exhibits a considerable plasticity. The migration pattern of crest cells in the developing body appears to be largely regulated by non-neural embryonic structures, rather than by the cells themselves. Also the expression of a phenotype can be influenced by nonneural structures after the cells have left the neural primordium.

GR-03 Sonic hedgehog: A new player in temporal control of somite formation

The transition to flowering is a fundamental switch in the lifetime of a plant and therefore tightly regulated. Genes controlling the transition in the model plant Arabidopsis thaliana are grouped into four major pathways. One of the most important outputs of these is the floral promoting factor FT. While genetic approaches have revealed most of the components necessary for flowering, there is not enough understanding yet to formally model how the floral transition switch operates and possesses a number of key properties, including stability, ability to integrate diverse environmental and endogenous signals as well as being rapid and biphasic. In an approach to conceptualize this biphasic switch we developed a mathematical model incorporating our current knowledge of the floral transition in Arabidopsis. We initially aimed at looking at the qualitative behaviour to verify whether the gene network structure was capable of reproducing the expected switches. By fitting in new data produced in the lab we were able to generate a quantitative model. Simulations we ran on flowering time mutants are very promising and show striking congruency between our simulations and experimental data. Our aim is to be able to predict the flowering time behaviour of mutants as well as wild type plants grown under various environmental conditions. This is especially important in the light of climate change, where the mean global temperature is expected to rise significantly which will have impact the flowering time of a wide range of species including crops.

Expression pattern of the receptor tyrosine‐kinase c‐kit and its ligand steel during avian development

EXPRESSION OF HSP70 DURING OOGENESIS AND EARLY DEVELOPMENT OF THE AMPHIBIAN PLEURODELES WALTL AFI-ER A HYPERTHERMIC TREATMTBT. PRUDHOMME Chris&&, MOREAU Nicole and ANGELIER Nicole. UPMC-CNRS UA1135 Groupe Genes ef DCveloppement 9, quai St-Bemnrd, 75005 PARIS, FRANCE. The expression of heat shock or stress proteins (hsp) is a well conserved response to stress that has been found in all cell types investigated so far, from bacteria to mammals. We have examined the expression of the inducible form of HSMO during oogenesis and early development of the Amphibian Pkurodeles zLhdt1. Defolliculated oocytes were heated at 34’C, 36’C or 37°C and maintained at these temperatures for 15 mn. After stress, the oocytes were placed at 2O’C for 1 hr or 4 hr. Samples were incubated 1 hr 30 in %-methionine. Equal amounts of cpm from the samples were analyzed by Western blotting. Autoradiographic signals showed that the amount of HSP70 in oocytes shocked at 37’C was higher than in the controls at all stages of oogenesis, which suggests that HSP70 was translationally regulated in Pleurodeles oocyte. During early development, embryos were maintained for 20 mn at 34”C, 36’C or 37°C and incubated 1 hr 30 in 35S-methionine at 20°C. Neosynthesis of HSP70 was analyzed by Western blotting. Autoradiographic results showed an increase of HSP70 neosynthesis in embryos shocked at 37’C from the midblastula stage. This stage is very important in development, as it coincides with the activation of the zygotic genome. Thus, we can suppose that a translationally regulation of Pleurodeles FBI’70 expression occurs from this stage on.