Characterization of Lrp, and Escherichia coli regulatory protein that mediates a global response to leucine

Exogenous leucine affects the expression of a number of different operons in Escherichia coli. For at least some of these operons, the leucine-related effect is mediated by a protein called Lrp (Leucine-responsive regulatory protein). The purification of Lrp to near homogeneity is described. Lrp is a moderately abundant, basic protein composed of two subunits of molecular mass 18.8 kDa each. In addition, the corresponding protein was purified from a strain having a mutation within the gene that encodes Lrp (lrp). This mutation (lrp-1) causes high constitutive expression of ilvIH, one of the operons controlled by Lrp (Platko, J. V., Willins, D.A., and Calvo, J.M. (1990) J. Bacteriol. 172, 4563-4570). The Lrp-1 and Lrp proteins have similar physical properties, but they show some differences in the characteristics with which they bind DNA upstream of the ilvIH promoter. The nucleotide sequences of the lrp and lrp-1 genes differ by only a single nucleotide, a C to G change that would substitute a Glu for an Asp at amino acid 114. Lrp has some amino acid sequence similarity to AsnC, a protein that regulates asnA expression (Kolling, R., and Lother, H. (1985) J. Bacteriol. 164, 310-315).

Law and science policy in federal regulation of formaldehyde

An examination of the way in which the Environmental Protection Agency, Occupational Safety and Health Administration, and Consumer Product Safety Commission each responded to evidence of formaldehyde's carcinogenicity in animal systems reveals the interplay between politics and science policy in regulatory determinations. In some cases there were significant and unjustified departures from reasoned decision-making. Agency decisions not to take action deserve special attention by citizens, the Congress, and the judiciary to ensure that federal regulatory agencies take the necessary steps to protect the public from significant health, safety, and environmental risks.

Stability and sex differences on the Coopersmith Self-esteem Inventory for students in grades two to twelve

This study reassessed the presence or absence of sex differences and investigated the stability of self-esteem as measured by Coopersmith's Self-esteem Inventory over 6 mo. for Grades 2 to 12. The subjects were 591 students, 296 male and 295 female, enrolled in an urban central Maine school district. No sex differences were found on any of the subscales or total scale score on either the pretest or posttests by grade. Significant correlations, small to moderate in size, were found for all grades on two scales, general self and total self. The results and implications are discussed.