Review of calcium methodologies.

A review of calcium methodologies for serum has been described. The analytical systems developed over the past century have been classified as to type beginning with gravimetry and extending to isotope dilution-mass spectrometry by covering all of the commonly used technics which have evolved during that period. Screening and referee procedures are discussed along with comparative sensitivities encountered between atomic absorption spectrophotometry and molecular absorption spectrophotometry.

Biochemical Changes in Terminal Root Galls Caused by an Ectoparasitic Nematode, Longidorus africanus - Nucleic Acids.

Changes in DNA and RNA in roots of bur marigold fed upon by Longidorus africanus were studied using analytical methods, radioactive precursors, and analytical CsC1 density-gradient centrifugation. The analyses showed that almost twice as much RNA and DNA was present in parasitized root tips as in those of nonparasitized control plants. Studies on the rates of incorporation of labeled thymidine and uridine confirmed the DNA levels determined by analytical methods, but revealed a much higher incorporation rate of RNA in healthy root tips than in those attacked by L.

The velocities of ion transport into and through the xylem of roots: findings with a two-point application pulse-chase technique.

Excised corn roots, Zea mays, had radioactively labeled solution applied at two points along their length, for 1 minute, and were then kept in dilute, unlabeled nutrient solution. During this "chase" period, exudate was collected at 1-minute intervals, and its content of radioions was determined. Two pulses of label appeared in succession, originating at the points of application near the cut end of the root and farther from the cut end, respectively.

Precursors of collagen secreted by cultured human fibroblasts.

Soluble precursors of collagen ("procollagens") in the culture medium of human diploid fibroblasts were characterized by molecular sieve chromatography on 6% agarose and by sodium dodecyl sulfate-acrylamide gel electrophoresis. Under the denaturing conditions for gels, the following molecular species were identified: a major species of three procollagen chains, a procollagen dimer, and free procollagen chains. Reduction with 2-mercaptoethanol completely dissociated the trimer and dimer, releasing procollagen alpha1 and procollagen alpha2 chains with molecular weights of about 120,000.