Abstract: This procedure comprises the following steps: (1) cleavage of a circular cloning vector comprising two restriction sites a and b giving cohesive ends which are compatible with one another, and two restriction sites c and d which are close to the restriction sites a and b, by restriction enzyme(s), (2) introduction by ligation of the nucleic acid sequence to be polymerized into the linearized vector obtained in (1), between the two restriction sites a and b (1x vector), (3) cleavage of the recircularized vector obtained in (2), by restriction enzyme(s), (4) introduction by ligation of a gene coding for a suppressor tRNA into the linearized vector obtained in (3), between the two restriction sites c and d (1x+s vector), (5) cleavage of the vector obtained in (4) by restriction enzyme(s), (6) introduction by ligation of the fragment a-d obtained in (5) (1x+s fragment) between the sites b and d of a 1x vector as obtained in (2), after cleavage of this 1x vector at the said sites b and d, (7) introduction by ligat

Abstract: A DNA sequence derived by the mutation from a ColE1-type replication origin is provided, wherein the sequence is characterized in that it includes at least one of the following mutations, which are defined in relation to the wild ColE1 origin: a Guanine to Adenine transversion in position 2976; and a Guanine deletion in position 3057. This sequence increases the number of copies of the plasmids which include it. Plasmids containing the replication origin, and their uses in the amplification of DNA sequences and the production of polypeptides by genetic engineering, are also disclosed.

Abstract: A X-MAC encoder enables a plurality of components to be encoded, each having a sequence of packets, with the packets being distributed in successive bursts each occupying a predetermined fraction of a television frame line. It comprises a plurality of blocks each having at least one packet encoder provided with a buffer memory for storing digital data coming from a source, and an encoder for distributing the packets in bursts of adjustable duration not greater than the duration of one television line. A base encoder assembly contains a programmable device for allocating a determined window of the television frame to each block. It calls a burst of length corresponding to the width within the window that is allocated by the programmable device, on the basis of the respective block burst encoder, at the beginning of each window in a line.