Children's family change: reports and records of mothers, fathers and children compared

Family change, when adults depart or arrive around children, raises policy issues. Its measurement depends upon the evidence collected and from whom. This paper compares British children's histories obtained from fathers and mothers. The evidence, on one birth cohort of parents, comes from two sources: the National Child Development Study and the ONS Longitudinal Study. The resulting account of family change is not substantially different between parents. There is some under-reporting of children not living with their fathers. This is due to under-reporting by those included in the studies and to under-representation in them of absent fathers and lone parents.     

Risks from ionizing radiation

For the public in the United Kingdom--and the United States--natural radon is a far greater radiation hazard than are emissions from nuclear installations.     

Site-directed mutagenesis reveals role of mobile arginine residue in lactate dehydrogenase catalysis

The binding of substrates to lactate dehydrogenases induces a marked rearrangement of the protein structure in which a 'loop' of polypeptide (residues 98-110) closes over the active site of the enzyme. In this rearrangement, arginine 109 (a basic residue conserved in all known lactate dehydrogenase sequences and in the homologous malate dehydrogenases) moves 0.8 nm from a position in the solvent to one in the active site where its guanidinium group resides within hydrogen bonding distance of both the reactive carbonyl of pyruvate and imidazole ring of the catalytic histidine 195 (see Fig. 1). Whilst this feature of the enzyme has been commented upon previously, the function of this mobile arginine residue during catalysis has not been tested experimentally. The advent of protein engineering has now enabled us to define the role of this basic residue by substituting it with the neutral glutamine. Transient kinetic and equilibrium studies of the mutant enzyme indicate that arginine 109 enhances the polarization of the pyruvate carbonyl group in the ground state and stabilizes the transition state. The gross active-site structure of the enzyme is not altered by the mutation since an alternative catalytic function of the enzyme (rate of addition of sulphite to NAD+), which does not require hydride transfer, is insensitive to the arginine----glutamine substitution.     

A bacteriocinogenic type 1 strain ofKlebsiella pneumoniae

Résumé La souche 1.2 (N.C.T.C. 5054) deKlebsiella pneumoniae est bactériocinogène. Sur 47 souches de Klebsiella étudiées 25% se sont révélées sensibles à cette bactériocine.

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We are grateful to ProfessorJ. P. Duguid, Drs.B. H. Park, I. Ørskov, andY. Hamon for strains and information.