Abstract: A plasmid for the production of porcine growth hormone or an analog thereof which upon introduction into a suitable bacterial host containing the thermolabile repressor C.sub.I renders the host cell capable, upon increasing the temperature of the host cell to a temperature at which the repressor is destroyed, of effecting expression of DNA encoding porcine growth hormone and production of porcine growth hormone or analogs thereof.

Abstract: An improved vector upon introduction into a suitable bacterial host containing the thermolabile repressor C.sub.I renders the host cell capable, upon increasing the temperature of the host cell to a temperature at which the repressor is destroyed, of effecting expression of a desired gene inserted into the vector and production of polypeptide encoded by the gene. The vector is a double-stranded DNA molecule which includes in 5' to 3' order the following: a DNA sequence which contains the promoter and operator P.sub.L O.sub.

Abstract: A method is provided for recovering a purified animal growth hormone or a polypeptide analog thereof having substantially the same amino acid sequence as, and the biological activity of, the corresponding naturally-occurring animal growth hormone from a bacterial cell in which the animal growth hormone or polypeptide analog has been produced by means of expression of a plasmid encoding the hormone or polypeptide analog which comprises: (a) disrupting the cell wall of the bacterial cell in a buffered neutral pH solution so as to produce a lysate containing precipitated hormone or polypeptide analog; (b) recovering the resulting precipitated hormone or polypeptide analog; (c) suspending the precipitated hormone or polypeptide analog so recovered in distilled water; (d) treating the resulting precipitate-containing suspension with a sodium hydroxide solution having an alkaline pH of about 11.

Abstract: An improved vector upon introduction into a suitable bacterial host containing the thermolabile repressor C.sub.I renders the host cell capable, upon increasing the temperature of the host cell to a temperature at which the repressor is destroyed, of effecting expression of a desired gene inserted into the vector and production of polypeptide encoded by the gene. The vector is a double-stranded DNA molecule which includes in 5' to 3' order the following: a DNA sequence which contains the promoter and operator P.sub.L O.sub.