Enzymatic synthesis of a blood group H-related glycosphingolipid by an alpha-fucosyltransferase from bovine spleen

An alpha-fucosyltransferase activity has been detected in a purified membrane preparation isolated from bovine spleen which catalyzes the transfer of L-fucose from GDP-L-[14C]-fucose to a tetraglycosylceramide (Lac-nTet-cer, Galbetal-4GlcNAcbeta1-3Galbeta1-4-Glc-cer) to form the blood group H-related glycosphingolipid. The membrane preparation contained a highly active endogenous nonlipid acceptor, which could be precipitated by 5% trichloroacetic acid or chloroform-methanol-water (6:3:5, v/v/v), whereas there was little endogenous glycosphingolipid acceptor. The optimum pH value for the incorporation of L-fucose was 6.4 in cacodylate-HCl buffer. The Km values were 0.6 mM and 0.36 mM for Lac-nTet-cer and GDP-L-fucose, respectively. The 14C-labeled product of the reaction was isolated and purified; it migrated with human erythrocyte blood group H-active pentaglycosylceramide. the terminal [14C]fucose was hydrolyzed 85% and 55% by 0.1 N trichloroacetic acid at 100 degrees for 2 hours and Charonia lampas alpha-fucosidase (19 hours at 37 degrees), respectively. The 14C-labeled product inhibited the hemagglutination reaction of O-type cells against eel anti H(O) globulin and formed a precipitin line with Ulex europeus lectin.

Prevalence of Salmonella serotypes in India: a 61-year study

During the period 1958-73, 8 027 strains of Salmonella were tested at the National Salmonella and Escherichia Centre: 3 834 strains from man, 3 018 from animals, 839 from sewage and water sources, and 336 of unknown origin. A total of 99 serotypes were identified: 47 from man, 83 from animals, and 35 from sewage and water sources. S. typhi was the commonest serotype in man, followed by S. weltevreden and S. paratyphi A. S. typhimurium was the commonest serotype isolated from animals, followed by S. weltevreden and S. anatum. In sewage and other water sources S. weltevreden was the commonest serotype identified followed by S. typhimurium and S. bareilly. Infection due to S. weltevreden in both man and animals increased considerably after 1970. Out of a total of 99 serotypes isolated from different sources, 13 were isolated from man only, 49 from animals only, 34 from both man and animals, 30 from both animals and water sources, and 22 from man, animals, and water sources.

Ultraviolet absorption and optical rotatory dispersion studies of deoxyribonucleic acid and nucleohistone

This report concerns the ultraviolet absorption and optical rotatory dispersion (ORD) of DNA and of nucleotides down to 185 mμ. An absorption band (y) at about 195 mμ occurs for all these compounds. Similar studies have been made on histones and nucleohistone. These indicate a strong absorption below 200 mμ due to protein. Consequently, if any native DNA is associated with some amount (2 - 12%) of protein (e.g., histones), the molecular absorption of DNA in the said region becomes masked, and no clear y-maximum due to DNA occurs in the absorption spectrum. The absorption of DNA in the y-band region (ca. 190 mμ) seems to be decreased as a result of DNA-protein interaction. No significant change is observed in the absorption region of DNA at longer wavelengths (250-290 mμ). The y-peak of DNA appears at about 190 mμ on complete removal of proteins. This peak is sharper than the conventional one (x) at 260 mμ and is hyperchromic on denaturation, and involves multiple Cotton effects to any degrees similar to that observed at the second peak (260 mμ).

The absorption (also ORD) features of nucleohistone at the x and y wavelengths do not provide similar information (e.g., denaturation artefacts) regarding the structure of the nucleohistone contained DNA which is apparently distinct from the structures of native and partially denatured (denaturation 10%) DNA. The weaker π-π* transition (190 mμ) in the DNA bases is very susceptible to nucleoprotein interaction. This result has been used to explain the influence of nucleoprotein interaction on the configuration of DNA in nucleohistone

Reaction of Vibrio cholerae and choleragenic toxin in ileal loop of laboratory animals

Accumulation of fluid in the ligated ileal loop upon injection of cholera vibrios or choleragenic toxin seems to be a generalized phenomenon in laboratory animals.

The role of DNA concentration

Melting temperatures (Tm) of several DNA’s do not vary with the change of DNA concentration. However, at any temperature above Tm, the fractional hyperchromism was always greater at the lower concentration. This result was also evident in the presence of formaldehyde.

Reversibility on renaturation decreased with the progress of thermal denaturation along the melting profile. The effect was much enhanced at low DNA concentration and for a DNA of low G—C content.

The occurrence of some permanent changes on the dissociated molecules has been suspected to be the only cause for the observed effects.

Spectrophotometric studies on aggregation of denatured DNA

Spectrophotometric studies have shown that aggregation of denatured DNA is dependent upon temperature (with an optimum at thirty seven degrees), concentration of the macromolecule, and on solvent conditions. The aggregates dissolve at very low (0°C) and high temperatures (60°C), and in very low concentrations of either macromolecule or salt in the solvent.