Abstract: Animals and animal embryos comprising cells having a genome comprising a recombinant endogenous recipient gene are provided. Methods of making animals and animal embryos comprising cells having a genome comprising a recombinant endogenous recipient gene are also provided.

Abstract: DNA gene inactivation constructs for homologous recombination in the genome of a mammalian cell are provided.

Abstract: A modified bioluminescent system comprising a fluorescent molecule covalently linked with a photoprotein, wherein said link between the two proteins has the function to stabilize the modified bioluminescent system and allowing the transfer of the energy by Chemiluminescence Resonance Energy Transfer (CRET).

Abstract: A hybrid protein (GFP-TTC) comprising the non-toxic proteolytic C fragment of tetanus toxin fused to green fluorescent protein was used to analyze the functional synaptic organization of neural networks. When injected intramuscularly in vivo, the GFP-TTC hybrid protein binds to tetanus neurotoxin receptors and clusters very rapidly to the active neuromuscular junction. Membrane traffic by GFP-TTC at the pre-synaptic level of the neuromuscular junction is strongly and rapidly influenced by exogenously co-injecting neurotrophic factors, such as BDNF, NT-4, and GDNF, but not by NGF, NT-3, and CNTF. The membrane traffic, directly detected using GFP-TTC in vivo, permits methods of analyzing synaptic functioning as well as methods of modulating neuronal transport using neurotrophic factors and agonists or antagonists thereof.

Abstract: The present invention relates to a process for targeted replacement of at least a part of an endogenous gene by at least a part of a foreign gene or targeted insertion of at least a part of a foreign gene at a targeted site in an endogenous gene in a cell by homologous recombination.

Abstract: A modified bioluminescent system comprising a fluorescent molecule covalently linked with a photoprotein, wherein said link between the two proteins has the function to stabilize the modified bioluminescent system and allowing the transfer of the energy by Chemiluminescence Resonance Energy Transfer (CRET).

Abstract: A modified bioluminescent system comprising a fluorescent molecule covalently linked with a photoprotein, wherein said link between the two proteins has the function to stabilize the modified bioluminescent system and allowing the transfer of the energy by Chemiluminescence Resonance Energy Transfer (CRET).

Abstract: A process for providing a recombinant, heterologous gene in the genome of a eukaryotic cell is provided. In particular, heterologous DNA is inserted into a recipient gene of the eukaryotic cell by homologous recombination. Moreover, a transgenic or chimeric animal comprising cells with DNA inserted into its genome by homologous recombination is disclosed. Further, the method of making these transgenic animal is taught.

Abstract: The present invention relates to a process for targeted replacement of at least a part of an endogenous gene by at least a part of a foreign gene or targeted insertion of at least a part of a foreign gene at a targeted site in an endogenous gene in a cell by homologous recombination.

Abstract: The non-toxic proteolytic C fragment of tetanus toxin (TTC peptide) has the same ability to bind nerve cells and be retrogradely transported through a synapse as the native toxin. A hybrid protein encoded by the IacZ-TTC gene fusion retains the biological functions of both proteins in vivo, i.e. retrograde transynaptic transport of the TTC fragment and &bgr;-gal enzymatic activity. After intramuscular injection, enzymatic activity could be detected in motoneurons and connected neurons of the brainstem areas. This strategy is useful for the delivery of a biological activity to neurons from the periphery to the central nervous system. Such a hybrid protein can also be used to map synaptic connections between neural cells.