Biomedical subjects

H W SEELEY

Publications and source records attributed to H W SEELEY.

16 recordsLinked to original sources

PubMed1963

TEMPERATURE-SENSITIVE DEXTRANSUCRASE SYNTHESIS BY A LACTOBACILLUS.

Dunican, L. K. (Cornell University, Ithaca, New York), and H. W. Seeley, Jr. Temperature-sensitive dextransucrase synthesis by a lactobacillus. J. Bacteriol. 86:1079-1083. 1963.-Dextran synthesis was found to be temperature-dependent in Lactobacillus strain RWM-13. Dextran was not formed above 37 C, although growth of cells occurred up to 42 C. Logarithmically growing cells transferred from 30 C to 40 C ceased producing dextran while growth decreased nominally. An examination of the extracts of cells broken by sonic treatment showed that as the temperature of growth was increased above 37 C the production of dextransucrase decreased. By use of an inhibitor of invertase, 10(-4)m AgNO(3), it was shown that invertase replaced dextransucrase activity at temperatures above 37 C. In contrast to dextransucrase in Leuconostoc mesenteroides, the enzyme in Lactobacillus strain RWM-13 was constitutive and thus resembled that of Streptococcus bovis. Thermosensitivity of dextransucrase synthesis has not been observed in Leuconostoc or Streptococcus.

Dextrans↗

PubMed1962

Starch hydrolysis by Strepto-coccus equinus.

Dunican, Lawrence K. (Cornell University, Ithaca, N. Y.) and Harry W. Seeley. Starch hydrolysis by Streptococcus equinus. J. Bacteriol. 82:264-269. 1962.-In a study of starch hydrolysis by strains of Streptococcus equinus, 52 isolates were obtained and their amylolytic abilities determined. It was found that all the strains could hydrolyze starch to some extent when grown in the presence of an easily fermentable carbohydrate, viz., glucose. Without this carbohydrate the organisms did not hydrolyze starch. The hydrolysis of starch was inhibited when the organisms were grown in an atmosphere of 5% CO(2) and 95% N(2), even if grown in the presence of a fermentable monosaccharide. S. bovis, which was used as a reference organism, readily hydrolyzed starch in the absence of monosaccharides and in atmospheres containing CO(2). In no instance did S. equinus hydrolyze the starch to the level of reducing sugars. Negligible amounts of reducing sugars were recovered when the cell-free filtrates of S. equinus were incubated with starch. With S. bovis, the yield of reducing sugars under such conditions was almost quantitative. These facts extend further the differences between these related organisms. The ability to synthesize an internal starchlike polysaccharide was noted in most of the strains of S. equinus. Synthesis was found when the organisms were grown on maltose or on a starch medium containing a small amount of fermentable monosaccharide.

Bacteria↗

PubMed1961

Nutrition of Streptococcus bovis in relation to dextran formation.

Barnes, Isabel J. (Cornell University, Ithaca, N. Y.), H. W. Seeley, and P. J. VanDeMark. Nutrition of Streptococcus bovis in relation to dextran formation. J. Bacteriol. 82:85-93. 1961.-Three nutritional types of Streptococcus bovis were encountered. Minimal media for their growth are described. Transferable growth in defined media was always accompanied by dextran production and the nutrition for dextran production could not be distinguished from the minimal nutritional requirements of the organism for growth. Measurable, free CO(2) was evolved from a complex medium during the growth of S. bovis. Several compounds were found to replace partially the CO(2) requirement of the species. When fractured cell preparations containing S. bovis dextran were employed as antigens, rabbits failed to yield sera which would precipitate S. bovis or leuconostoc dextrans.

Dextrans↗

PubMed1960