No abstract

The haemolymph of a number of insects has been shown to contain the non-reducing disaccharide trehalose as the principal carbohydrate (Wyatt & Kalf, 1956, 1957). This is so in the desert locust, Yeast cells are also able to convert glucose into trehalose, and Cabib & Leloir (1958) have shown that yeast contains an enzyme which catalyses the reaction: uridine diphosphate glucose + glucose 6-phosphate = uridine diphosphate + trehalose phosphate. Schi8tocerca gregaria, the haemolymph of which may contain up to 2 % of trehalose (Howden & Kilby, 1956). Treherne (1958a, b) demonstrated that the introduction of radioactive glucose into the alimentary canal or directly into the haemolymph of S. gregaria in vsvo resulted in the appearance of radioactive trehalose in the haemolymph within a short time, but the site and mode of conversion of glucose into trehalose were not investigated. We have been able to show that the fat body is the most active tissue of the locust in this respect. The insect fat body is a conspicuous organ which extends throughout the abdominal and thoracic cavities, and consists of a loose meshwork of 8 hr. against three changes of distilled water at 5°. The dialysate was then freeze-dried and stored at-20°until used. Paper chromatography. Solvents used for the chromatographyof sugarswere: solvent 1, propan-1-ol-ethyl acetatewater (7:1:2, by vol.

No abstract

Although the structure of streptomycin has been known for some time, the process of its biosynthesis by Streptomyce8 gri8eua has not yet been elucidated. Blumsom & Baddiley (1961) examined extracts of S. gri8eU8 for nucleotide-sugar compounds which may be involved in synthesis of the streptose and N-methyl-L-glucosamine moieties of streptomycin. They found thymidine diphosphate rhamnose a possible intermediate for streptose, but no compounds more closely related to streptomycin were identified. Other workers have grown S. gri8eu8 in the presence of labelled compounds and examined the incorporation of the isotope into the streptomycin produced. Such experiments were first carried out by Karow, Peck, Rosenblum & Wood

1. Streptomyces griseus was grown in a medium containing l-[Me-(14)C]methionine, and the labelled products from an ethanolic extract of the cells were examined. 2. Acid hydrolysis of one of the products gave a compound identified as 3-O-[Me-(14)C]-methylmannose by a series of degradative reactions. 3. Reduction of the radioactive compound gave 3-O-methyl-d-mannitol, indistinguishable from a synthetic sample.