FULL-TERM DEVELOPMENT OF ENUCLEATED OOCYTES INJECTED WITH CUMULUS CELL NUCLEI

Until recently, fertilization was the only way to produce viable mammalian offspring, a process implicitly involving male and female gametes. However, techniques involving fusion of embryonic or fetal somatic cells with enucleated oocytes have become steadily more successful in generating cloned young. Dolly the sheep was produced by electrofusion of sheep mammary-derived cells with enucleated sheep oocytes. Here we investigate the factors governing embryonic development by introducing nuclei from somatic cells (Sertoli, neuronal and cumulus cells) taken from adult mice into enucleated mouse oocytes. We found that some enucleated oocytes receiving Sertoli or neuronal nuclei developed in vitro and implanted following transfer, but none developed beyond 8.5 days post coitum; however, a high percentage of enucleated oocytes receiving cumulus nuclei developed in vitro. Once transferred, many of these embryos implanted and, although most were subsequently resorbed, a significant proportion (2 to 2.8%) developed to term. These experiments show that for mammals, nuclei from terminally differentiated, adult somatic cells of known phenotype introduced into enucleated oocytes are capable of supporting full development

Molecular characterization of glutathione reductase cDNAs from pea (Pisum sativum L.).

A cDNA for pea glutathione reductase has been cloned and sequenced. The derived amino acid sequence of 562 residues shows a high degree of homology to the previously published GR sequences from human erythrocytes and from two prokaryotes: Escherichia coli and Pseudomonas aeruginosa. The pea enzyme differs from other GRs in having an M-terminal leader sequence of about 60–70 residues which may be a chloroplast transit peptide and a 20 amino acid C-terminal extension of unknown function

Interactions of Neisseria meningitidis with cells of the human meninges

The interaction of Neisseria meningitidis with the meninges that surround and protect the brain is a pivotal event in the progression of bacterial meningitis. Two models of the human meninges were established in vitro, using (i) sections of fresh human brain and (ii) cultures of viable cells grown from human meningiomas. Neisseria meningitidis showed a specific predilection for binding to the leptomeninges and meningeal blood vessels in human brain and not to the cerebral cortex. There was a close correlation between the adherence of different Neisseria species to leptomeninges and cultured cells. The major ligand that mediated adherence was the pilus, and pilin variation modulated the interactions. The presence of Opa protein increased the association of Cap+ meningococci that expressed low-adhesive pili, but did not influence the association of high-adhesive pili. In contrast, Opc did not influence the adherence of Cap+ meningococci, whereas loss of capsule was associated with a more intimate interaction between the bacteria and the meningioma cell that was not apparent with Cap+ meningococci. There was no evidence of internalization of meningococci by meningioma cells in vitro, an observation that is consistent with the barrier properties of the leptomeninges to N. meningitidis observed in vivo