Genotype of Yupik Eskimos with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Summary An A-to-G transition in the second intron was the sole mutation detected in four Yupik Eskimo patients with salt-wasting congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency. Allele-specific hybridization should be an efficient means of performing prenatal diagnosis of the disease in this highly inbred population.     

Phenylketonuria—Experience at One Center in the First Year of Screening in California

One year''s experience with phenylketonuria during the calendar year 1966, the first year for compulsory newborn screening in California, was reviewed. The over-all prevalence rate from reported cases in California during this period was one case per 19,500 persons tested. Fifty-seven persons suspected of having pku were evaluated, and 25 of them were determined to be phenylketonuric. Eleven of the 25 were infants in whom the abnormality was detected through the newborn screening program or because it was detected in a sibling through a screening program. All the newborn phenylketonuric patients were developing normally at the time of last report (although the follow-up periods were short).In nine of the other children, pku was detected because they were retarded. Five retarded children who were diagnosed as phenylketonuric at another clinic were given dietary assistance.Five additional infants had elevated serum phenylalanines but did not have the classic biochemical findings of pku and are being evaluated further. Nine infants with positive screening tests exhibited biochemical and clinical findings consistent with transient tyrosinemia. Eighteen other children were evaluated and found to have no metabolic abnormality.The newborn screening program for pku is of decided benefit in early identification of a group of infants who have a high rate of potentially serious metabolic disease. Early identification permits treatment soon enough to prevent mental retardation. Newly identified patients should be evaluated in a medical setting capable of careful pediatric, biochemical and nutritional surveillance.     

Isolation of High-Frequency Recombining Strains from Escherichia coli Containing the V Colicinogenic Factor

The isolation and characterization of high-frequency recombining strains from different Escherichia coli host cells containing either the F factor or the Col V factor are described. The strains (with one exception) formed from three of the V⁺ parents showed the same origin and polarity of transfer (xyl-arg-pro-trp-his-mal). The Hfr strains formed from the one remaining V⁺ and the F⁺ host cells showed a greater variety in their points of origin. In addition, several Hfr strains isolated from V⁺ parents lost the ability to produce colicin V. F_v⁺ segregants of these were isolated, and the F_v factors appeared to retain their preferential site for Hfr formation, but they lacked other propertes controlled by the Col V factor. Chromosomal integration of episomes and its relation to the fertility of F⁺ and V⁺ strains are discussed. Production of colicin V appeared to be uninfluenced by the state of the Col V factor within the cell.     

Intracellular aminopeptidases inStreptomyces lividans 66

Summary We have investigated the aminopeptidase activities present inStreptomyces lividans strains. The majority of these activities proved to be intracellular with multiple active species. Two aminopeptidase P genes were identified to be responsible for the ability to hydrolyze amino terminal peptide bonds adjacent to proline residues. Two other broad spectrum aminopeptidases were found to display homology at both the DNA and protein levels. One showed significant homology to PepN proteins, particularly around the putative zinc-binding residues which are important for catalysis. The second broad spectrum activity was not analyzed in detail but showed a different spectrum of substrate specificity to that of PepN.     

Characterization and immunocytochemical demonstration of glucocorticoid receptor using antisera specific to transformed receptor

Cytosolic and nuclear forms of the glucocorticoid receptor were characterized using immunochemical techniques. Antibodies were raised in rabbits to an M_r 58,000 fragment of the transformed (DNA-binding) glucocorticoid receptor purified from rat liver cytosol by DNA-cellulose chromatography and polyacrylamide gel electrophoresis. Antibodies reacted with the transformed receptor form in a radioimmunoassay for glucocorticoid receptor. Western blot analysis of antibody reactivity revealed a single M_r 185,000 receptor form in rat liver cytosol but a smaller M_r 85,000 form in nucleosol, indicating the M_r 85,000 form is the transformed receptor. Furthermore, western blot analysis indicates that the M_r 185,000 receptor undergoes proteolysis during receptor purification and in vitro transformation processes by generating immunochemically similar proteins of smaller molecular weights. An identical M_r 185,000 glucocorticoid receptor was detected in cytosols of four rat tissues; liver, brain, adrenal medulla, and thymus. The glucocorticoid receptor was localized to the cytoplasm and nucleus of rat adrenal medulla cells by immunohistochemistry, demonstrating the existence in vivo of the transformed receptor and translocation of the receptor from cytoplasm to nucleus.     

Increased recovery of salmonellae from environmental samples enriched with buffered peptone water.

The incidence and persistence of salmonellae in weather pools on the top of Stone Mountain were investigated with lactose and buffered peptone water used as pre-enrichment broths. A total of 162 samples were collected from 16 weather pools over a 3-month period. The use of buffered peptone water increased the recovery of salmonellae by approximately 25%. The combined use of direct enrichment in tetrathionate broth containing brilliant green dye and pre-enrichment in buffered peptone water followed by enrichment in tetrathionate broth made it possible to detect all 37 of the contaminated samples. All of the isolates were Salmonella bareilly, the only serotype recovered in a previous study. All but one of the isolations were made from moist or wet samples. S. bareilly was isolated from rabbit dung and litter collected near the weather pools, but attempts to trap rabbits for study were unsuccessful. Random samples taken along a side of the mountain yielded S. bareilly in weather pools within the upper third of the mountain; below this level, S. weslaco and S. memphis were recovered, but not S. bareilly.     

Enhanced virulence effect of K1 polysaccharide in neonatal rats challenged withE. coli

Purified K1 polysaccharide enhanced the virulence of non-K1Escherichia coli species when given by orogastric feeding to neonatal rats. Neonatal rats developedE. coli bacteremia when K1 polysaccharide was given concomitantly with non-K1E. coli, whereasE. coli bacteremia did not develop when non-K1E. coli was given alone.E. coli K1 species did cause bacteremia and meningitis when fed to neonatal rats. The mechanism by which k1 polysaccharide enhances virulence can be studied with this model of bacteremia development in neonatal rats.     

Further Tests of a Recombination Model in Which χ Removes the Recd Subunit from the Recbcd Enzyme of Escherichia Coli

When one of two infecting lambda phage types in a replication-blocked cross is chi + and DNA packaging is divorced from the RecBCD-chi interaction, complementary chi-stimulated recombinants are recovered equally in mass lysates only if the chi + parent is in excess in the infecting parental mixture. Otherwise, the chi 0 recombinant is recovered in excess. This observation implies that, along with the chi 0 chromosome, two chi + parent chromosomes are involved in the formation of each chi + recombinant. The trimolecular nature of chi +-stimulated recombination is manifest in recombination between lambda and a plasmid. When lambda recombines with a plasmid via the RecBCD pathway, the resulting chromosome has an enhanced probability of undergoing lambda x lambda recombination in the interval into which the plasmid was incorporated. These two observations support a model in which DNA is degraded by Exo V from cos, the sequence that determines the end of packaged lambda DNA and acts as point of entry for RecBCD enzyme, to chi, the DNA sequence that stimulates the RecBCD enzyme to effect recombination. The model supposes that chi acts by ejecting the RecD subunit from the RecBCD enzyme with two consequences. (1) ExoV activity is blocked leaving a highly recombinagenic, frayed duplex end near chi, and (2) as the enzyme stripped of the RecD subunit travels beyond chi it is competent to catalyze reciprocal recombination.