PubMed Health⌕ Search

Biomedical subjects

C L Ginther

Publications and source records attributed to C L Ginther.

9 recordsLinked to original sources
PubMed1996

DNA sequencing using a four-color confocal fluorescence capillary array scanner.

The design, construction and operation of a four-color capillary array electrophoresis scanner are presented. The use of sensitive energy transfer primers facilitates four-color detection of the DNA sequencing fragments following excitation at a single laser wavelength (488 nm). This scanner collects fluorescence data from up to 25 capillaries in parallel. The resulting four-color image files are automatically reduced to four-color line plots, and a base-calling program (Sax) is used to call the sequence. The performance of this system for DNA sequencing is demonstrated by examining twelve different motifs of the hypervariable region I of human mitochondrial (mt) DNA obtained from a Sierra Leone population.

Base Sequence↗
PubMed1981

Production of an aromatic amino acid auxotroph of a trimethoprim-resistant Escherichia coli and deuteration of the aromatic amino acids in its dihydrofolate reductase.

Interpretation of the 1H-NMR spectra of Escherichia coli dihydrofolate reductase is complicated by the large number of overlapping resonances due to protonated aromatic amino acids. Deuteration of the aromatic protons of aromatic amino acid residues is one technique useful for simplifying the 1H-NMR spectra. Previous attempts to label the dihydrofolate reductase from overproducing strains of Escherichia coli were not completely successful. This labeling problem was solved by transducing via P1 phage a genetic block into the de novo biosynthetic pathway of aromatic amino acids in a trimethoprim resistant strain of E. coli, MB 3746. A new strain, MB 4065, is a very high level producer of dihydrofolate reductase and requires exogenous aromatic amino acids for growth, therefore allowing efficient labeling of its dihydrofolate reductase with exogenous deuterated aromatic amino acid.

Amino Acids↗
PubMed1979

Sporulation and the production of serine protease and cephamycin C by Streptomyces lactamdurans.

Streptomyces lactamdurans, producer of the antibiotic cephamycin C, excretes at least two proteases. Physiological studies indicate that antibiotic synthesis and serine protease formation are coordinately regulated. Both are produced only after culture growth ends, and they appear with essentially identical kinetics. In addition, strains which produce superior levels of cephamycin C form equally superior levels of the serine protease. Genetic evidence reveals that the syntheses of the antibiotic and serine proteases are associated with sporulation. Mutants which fail to produce aerial hyphae (bald mutants) also fail to synthesize the antibiotic and serine proteases.

Cephalosporins↗
PubMed1977

Erythromycin resistant mutations in Bacillus subtilis cause temperature sensitive sporulation.

All of several hundred erythromycin resistant single site mutants of Bacillus subtilis W168 are temperature senstive for sporulation. The mutants and wild type cells grow vegetatively at essentially the same rates at both permissive (30 degrees C) and nonpermissive (47 degrees C) temperatures. In addition cellular protein synthesis, cell mass increases and cell viabilities are similar in mutant and wild type strains for several hours after the end of vegetative growth (47 degrees C). in the mutants examined, the temperature sensitive periods begin when the sporulation process is approximately 40% completed, and end when the process is 90% completed. At nonpermissive temperatures, the mutants produce serine and metal proteases at 50% of the wild type rate, accumulate serine esterase at 16% of the wild type rate, and do not demonstrate a sporulation related increase in alkaline phosphatase activity. The eryR and spots phenotypes cotransform 100%, and cotransduce 100% using phage PBS1. Revertants selected for ability to sporulate normally at 47 degrees C (spot), simultaneously regain parental sensitivity to erthromycin. No second site revertants are found. Ribosomes from eryR spots strains bind erythromycin at less than 1% of the wild type rate. A single 50S protein (L17) from mutant ribosomes shows an altered electrophoretic mobility. Ribosomes from spo+ revertants bind erythromycin like parental ribosomes and their proteins are electrophoretically identical to wild type. These data indicate that the L17 protein of the 50S ribosomal subunit from Bacillus subtilis may participate specifically in the sporulation process.

Bacillus subtilis↗
PubMed1974

Cold-sensitive mutant of Salmonella typhimurium defective in nucleosidediphosphokinase.

A cold-sensitive mutant of Salmonella typhimurium defective in nucleosidediphosphokinase (ATP:nucleosidediphosphate phosphotransferase, EC 2.7.4.6) has been isolated and characterized. The mutant contains only 2% of the enzyme activity found in the parent, and the heat lability of this activity is 10 times that from the parent at 33 C. Mutant extracts lack the ability to convert any of 11 nucleoside diphosphates tested to the corresponding nucleoside triphosphates, but the nucleosidemonophosphatase activities are normal. Although the nucleoside triphosphate pools of the mutant are depressed significantly at the restrictive temperature (20 C), they are slightly elevated at the permissive temperature (37 C). The levels of guanosine pentaphosphate and guanosine tetraphosphate are dramatically increased. Two representative enzymes of pyrimidine de novo synthesis, aspartic transcarbamylase and dihydroorotate dehydrogenase, are fully repressed at both 37 and 20 C. Intracellular pools of uridine diphosphate are depressed at both permissive and restrictive temperature.

Adenosine Triphosphate↗