A model for studying the initiation of normal calcification in vivo

1. Rat costal cartilage was found to begin to calcify normally when the rats weigh 35-45g. 2. The cartilage is suggested as a model for the study in vivo of mechanisms concerned with normal calcification. 3. The model was tested by studying the incorporation of fluoride into the mineral deposited in the tissue. 4. The percentage of inorganic material in cartilage rose from approx. 3% of the dry weight in the uncalcified tissue to 62% in the tissue from rats weighing 300g. 5. Mineral deposited had a calcium/phosphorus molar ratio of 1.65. 6. After the oral administration of sodium fluoride to rats, fluoride was incorporated into cartilage mineral. 7. The concentration of fluoride in cartilage ash increased rapidly with calcification and the mineral became more highly fluoridated than the corresponding rib bone. 8. Fluoridated mineral showed a marked decrease in citrate concentration.     

On some species ofHabrolepis Foester andAdelencyrtus Ashmead [Hymenoptera: Encyrtidae] in Southern Africa and mauritius

A key is given for the identification of seven species — including three newly described ones — ofHabrolepis Foerster in southern Africa. Two species ofAdelencyrtus Ashmead are recorded and annotated. One of these is a new record for the Ethiopian region.     

Oxidation ofn-alkanes to ketones by anArthrobacter species

AnArthrobacter strain isolated from soil and selected for poor ability to utilize hexadecane as sole C-source was grown in a hexadecane (or pentadecane) — salts medium supplemented with yeast extract or corn steep liquor as the source of carbon for growth. It accumulated mono-hexadecanones (or pentadecanones). The percentages to which the individual ketones were accumulated depended on the distance of the carbonyl group from the terminal end of the substrate hydrocarbon; the greater the distance, the lower the percentage. The percentages did not depend on the composition of the medium. No other hydrocarbon oxidation products were observed.These results are discussed in relation to other reports of microbial conversions of alkanes to ketones.This research was authorized for publication as paper no. 3331 in the journal series of the Pennsylvania Agricultural Experiment Station, on December 7, 1967.     

Tryptophan Synthetic Pathway and Its Regulation in Chromobacterium violaceum

Extracts of Chromobacterium violaceum catalyzed all of the reactions involved in synthesizing tryptophan from chorismic acid. Tryptophan auxotrophs which had lost any of these activities did not produce the characteristic purple pigment, violacein, when grown on a medium in which tryptophan was limiting. Gel filtration of extracts allowed us to estimate molecular weights for the tryptophan enzymes. All of the enzymes appeared to have molecular weights below 100,000. No enzymes were observed to occur in aggregates. The specific activities of the enzymes of the tryptophan pathway did not change when mutants were grown under conditions of limiting or excess tryptophan. The first enzyme in the pathway, anthranilate synthetase, was subject to feedback control by the end product, tryptophan. Tryptophan acted as a noncompetitive inhibitor with respect to glutamine, one of the substrates for anthranilate synthetase, and as a competitive inhibitor of the reaction when chorismate, the other substrate, was varied. The nonlinearity observed in the Lineweaver-Burk plot in the latter case suggests that there may be more than one chorismate-binding site on anthranilate synthetase.     

Acridine Sensitivity of Bacteriophage T2H in Escherichia coli

Normally acridine-sensitive, Escherichia coli-T2H complexes are rendered acridine-resistant if the infecting bacteriophage mutant is either pr or q. If these pr or q mutants are treated to produce sensitive revertants, one obtains a mutation at any of several dye-sensitizing (ds) sites in the early enzyme region of the T2 map. The ds mutants are nonspecific suppressors because they reduce the resistance of complexes containing either pr or q to proflavine. The ds mutants are not identical in action, since some make pr or q sensitive to proflavine and quinacrine, and others, to proflavine alone. Two ds mutants have r to r(+) mutation patterns which differ, depending upon whether or not the ds is coupled with r7 (an rII mutant). The mutation patterns of r(+) to r are the same for both ds mutants and for wild type. We suggest that dye sensitization may consist of alterations of early enzymes so as to produce slightly different forms of deoxyribonucleic acid which are in turn dyesensitive.     

Aerobic respiratory activity of the yeastlike phase of Sporotrichum schenckii as affected by high hydrogen ion concentrations

Summary Six strains ofSporotrichum schenckii were studied in regard to the effect of hydrogen ion concentration on certain aspects of the aerobic respiratory activity of the yeastlike phase.Optimal oxygen uptake of endogenous respiration occurred at pH 2.0, although no effects were observed on the oxygen-carbon dioxide exchange ratio (respiratory quotient) at this pH value when compared to the R.Q. obtained at pH 7.0. Endogenous respiratory activity at both pH 2 and 7 was markedly sensitive to the presence of certain respiratory inhibitors.Optimal respiratory activity using glucose as substrate occurred at pH 7.0 .On the other hand, oxidation of pyruvate as substrate proceeded at significant rates only at pH values below pH 4.0. With decreasing hydrogen ion concentration, accumulation of this organic acid occurred when glucose was employed as substrate. With the exception of acetate, none of the organic acid respiratory intermediates were found to stimulate respiration.The results reported herein suggest that the respiratory activity of the yeastlike phase ofS. schenckii differs in several respects from that observed for the yeastlike phases ofHistoplasma capsulatum andBlastomyces dermatitidis.From the Research Laboratory, Veterans Administration Hospital, Kansas City, Missouri, and The Department of Microbiology, Kansas University Medical Center, Kansas City, Kansas.Supported in part by USPHS Grant AI 03485.     

Zone Centrifugation in a Cesium Chloride Density Gradient Caused by Temperature Change

In this communication is described a new technique for the determination of sedimentation coefficients of macromolecules banded in equilibrium density gradients. Initially, the macromolecules are banded in the analytical ultracentrifuge at a low temperature of about 5°C. After equilibrium has been obtained, the temperature is increased to 25°C. The equilibrium band will now sediment to a new equilibrium position in the ultracentrifuge cell: (a) By following the position of the migrating band as a function of time, sedimentation coefficients may be determined. (b) If several species having different sedimentation coefficients are present in the original band, then during the course of the migration the band may split into several new bands which eventually reunite at the final equilibrium position. (c) If different chemical species of macromolecules such as nucleic acids and carbohydrates are present, in general they will exhibit different temperature density relationships, and can move different distances and directions in response to temperature change.     

Production and Partial Purification of Antibiotic Materials Formed by Physarum gyrosum

Pure cultures of Physarum gyrosum were grown on agar plates with autoclaved Escherichia coli suspensions as the growth medium. Portions of such agar, after growth of the slime mold, contained diffusible materials that inhibited the growth of Bacillus subtilis, B. cereus, E. coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Paper chromatography of extracts of such cultures revealed at least three different active fractions. Preliminary fractionations increased the specific activity by one order of magnitude, probably in part by removal of inactive material and in part by separating active components. The fractionations also demonstrated the multiplicity of the antibiotic activity. Fractions variously obtained always retarded the growth of the bacterial species listed above.     

Linkage of PGK1 to X-linked severe combined immunodeficiency (IMD4) allows predictive testing in families with no surviving male

Summary We present a linkage map of DNA probes around the X-linked severe combined immunodeficiency (IMD4) locus at Xq11-13. DXS159 and PGK1 show no cross-overs with the disease locus (Lod 3.01 at = 0.00). The order of loci is DXS1-DXS106-(DXS159-PGK1-IMD4)-DXS72-DXYS1. Members of families whose carrier status has been established by X-inactivation patterns were included in the analysis. As the probe (pSPT/PGK), which is used for investigation of X-inactivation patterns, has been shown to be linked to the disease itself, it is possible to assign phase in mothers of sporadic cases who have been shown to be carriers, even when they have no surviving male offspring.