Numerous biopharmaceuticals and other recombinant biotechnology products are made in prokaryotic hosts. However, bacterial production of native, biologically active eukaryotic proteins is rarely possible for disulfide-bonded and/or multisubunit proteins. We previously described the production of soluble, native disulfide-bonded dimeric proteins in the Escherichia coli cytoplasm (Miele et al., 1990; Mantile et al., 1993). Native, biologically active proteins with up to six disulfide bonds have been produced with our expression system (Garces et al., 1997). However, plasmid instability during induction limited its usefulness. We now report the stable, high-level expression of soluble, disulfide-bonded human uteroglobin without antibiotic selection. We designed a new vector containing a multifunctional stabilization region that confers complete plasmid stability and increased protein yields without copy number increases. Recombinant expression remains fully inducible after long-term continuous culture in nonselective liquid medium (at least 260 generations). This system may significantly expand the applications of bacterial expression to recombinant production of soluble, bioactive proteins for biochemical studies and biopharmaceutical/industrial purposes. As a result of the very broad activity spectrum of the stabilization region we selected, its use could be extended to bacterial hosts other than enterobacteria.

Anti-Bacterial Agents↗

PubMedDate not supplied

Embryonic characteristics in superovulated mouse strains. Comparative analyses of the incidence of chromosomal aberrations, morphological malformations, and mortality of embryos from two strains of superovulated mice.

Superovulation was induced in an inbred (C3HeB/FeJ) and a random-bred (CD-1) strain of mice and pregnant females were serially sacrificed from 6-15 days of gestation. All embryos were examined chromosomally and by external morphology. A G-banding technique was used to detect specific chromosomal constitutions. The common types of chromosomal aberrations were monosomies and trisomies. Our results showed that the proportion of chromosomally abnormal embryos was significantly greater in the superovulated group of inbred mice, than in the spontaneously ovulating inbred group, an observation not made in the random-bred mice. In each strain, superovulation yielded a significantly higher proportion of morphologically malformed embryos, but no significant difference between strains with respect to this criterion was noted after superovulation. There was a significant increase in the post-implantation embryonic mortality in the random-bred strain but not in the inbred strain following superovulation. This study indicates that each strain has its intrinsic pattern with regard to the fate of embryos following superovulation.

Animals↗