Roger M. Herriott

Penetration of deoxyribonucleic acid into Hemophilus influenzae

Abstract An analysis has been made of some of the factors influencing the uptake of 32 P-labeled transforming DNA by competent Hemophilus influenzae . The pH and ionic strength of the medium, the extent of sonication, and denaturation of the DNA influenced the quantitative adsorption of 32 P-labeled material. These findings suggest that the initial attraction or interaction of DNA with competent cells is probably ionic in nature. The second, or irreversible, step in uptake showed pH, ionic strength and temperature optima and was reduced by the metabolic inhibitors 2,4-dinitrophenol, sodium azide, and iodoacetate. Irreversible uptake was also reduced by sonic breakdown and by heat denaturation of the DNA. It is concluded that a highly ordered and specific mechanism is involved in the transport of native polymerized DNA into Hemophilus influenzae .

Nucleases and their inhibitors in the cellular components of human blood.

The inhibitors of nucleases in various cellular components of human blood have been determined as a follow-up of an earlier study on the nuclease level of human blood, plasma and serum. WBC contain a DNase inhibitor which is released into the medium as these cells are incubated. RNase activity equivalent to that found in whole blood is present in sonically disrupted WBC. Lysed RBC contain appreciable quantities of DNase inhibitor and comparatively little RNase inhibitor. On incubation of serum, the high DNase activity disappears, and it has been shown that an inhibitor develops which will reduce the activity of added pancreatic DNase. A concentration of 0.01 M Mg++ accelerates this release of DNase inhibitor. These findings can explain the conflicting reports on the nuclease content of blood and blood products. The relationship of these findings to the possible survival of viral nucleic acids is discussed.

Structural changes associated with the conversion of pepsinogen to pepsin. I. The N-terminal amino acid residue and amino acid composition of the pepsin inhibitor.

Abstract 1. 1. The inhibitor of pepsin, found in the activation mixture of pepsinogen, has been isolated with the aid of ion exchange columns. 2. 2. A DNP-end group analysis revealed the presence of only one terminal residue which was identified as leucine. 3. 3. A complete analysis of the amino acids in the inhibitor was obtained using chromatography on the ion exchange resin Dowex-50-X 4 . 4. 4. The molecular weight of the inhibitor calculated from the DNP leucine content of the inhibitor and from the summation of the amino acid residues led to values of 3100 and 3242 respectively.

Effects on DNA: Transforming Principle

Genetic transformation in bacteria involves the transfer of hereditary determinants from ruptured or lysed cells of one strain to a recipient strain which then develops characteristics of the donor cell line. It was this experiment which led to the discovery that DNA is the carrier of heritable properties (Avery et al., 1944). DNA can be purified and stored and will confer the specific properties soon after being incorporated by recipient cells. DNA from transformable bacteria is particularly suited for studies of mutagenesis for it is quite stable and its genetic characteristics can be assayed relatively precisely.

Purification of the photoreactivating enzyme from yeast

A method of purifying the DNA photolyase (EC 4.1.99.3) from yeast has been developed. The method includes one step which has been included to destroy enzymes that may be responsible for the instability of purified preparations.

Inosine and lactate: factors critical during growth for development of competence in Haemophilus influenzae.

Abstract Competence in bacteria is the capacity of the cells to take up extracellular DNA from the medium. The development of competence in H. influenzae takes place in two phases. In phase one the organisms are grown and in phase two competence is developed (Goodgal & Herriott, 1961) . High levels of competence develop when the medium for both phases is Difco brain heart infusion broth (B-H) supplemented with hemin and nicotinamide adeninedinucleotide (NAD). It was observed that when cells were grown in a chemically defined medium they failed to yield comparable high levels of competence even though the second phase medium was B-H (Talmadge & Herriott, 1960) . This suggested that B-H contained unrecognized competence promoting activity that was essential during growth. The present report describes evidence that inosine and L(+) lactate together, have such activity.