Nonspecific inhibition of precursor uptake by alkyl-substituted purines and prednisolone

Of 43 compounds, encompassing a wide variety of biological activities, only the same six (9-cyclopentyladenine, 9-benzyladenine,9-n-butyladenine, 6-benzylthiopurine, 9-cyclopentyl-6-mercaptopurine, and prednisolone), at concentrations less than 10 times the toxic amounts, inhibited precursor incorporation into lipids, glycoproteins, and DNA of logarithmically-growing adenocarcinoma 755 and leukemia LI 210 cells in culture. For adenocarcinoma 755 cells, each of the six agents, added subsequent to choline, had little effect on the incorporation of choline into lipids, an indication that their action was on uptake of the precursor rather than on a bio-synthetic step. Direct measurements of choline and thymidine uptake into cells of both types showed that each of the six agents apparently blocked choline incorporation into lipids and thymidine incorporation into nucleic acids by inhibiting uptake of the precursors.     

Effects of acriflavine on the mitochondria and kinetoplast of Crithidia fasciculata. Correlation of fine structure changes with decreased mitochondrial enzyme activity

The effects of acriflavine on the fine structure and function of the mitochondria and the kinetoplast in Crithidia fasciculata have been investigated. A mitochondrial fraction was prepared by differential centrifugation of cells broken by grinding with neutral alumina. Isolated mitochondria or intact cells revealed by spectrophotometric measurements the presence of cytochromes a + a ₃, b, c ₅₅₅ and o. After cells were grown in acriflavine for 3–4 days, the fine structure of the mitochondria and their cytochrome content were affected. Cells grown in 5.0 µM acriflavine had a threefold decrease in cytochrome a + a ₃ and decreased respiratory activity. The mitochondrial preparation from these cells had a fivefold decrease in cytochrome a + a ₃ and a less but significant decrease of other cytochromes present. There was also a decrease in the mitochondrial enzyme activities of NADH, succinic and L-α-glycerophosphate oxidases, and succinic and L-α-glycerophosphate dehydrogenases. Dyskinetoplastic cells could be demonstrated after growth in 1.0 µM acriflavine. At 5 µM, 80–90% of the cells were dyskinetoplastic. The kinetoplastic DNA was condensed, nonfibrillar, and did not incorporate thymidine-³H. The mitochondria in these cells had few cristae and were shorter and more swollen than the controls. Acriflavine may induce the fine structure effects we have observed and may affect the formation of the mitochondria in C. fasciculata.     

On the morphology,behaviour and systematic status of the assam macaque (Macaca assamensis McClelland, 1839)

Studies on a living and freshly dead male ofM. assamensis at Y.R.P.R.C. supplemented by notes on a living pair and their male offspring observed at the Z.S.L., enable us to supplement existing data on the somatology, craniology, dental anatomy and behavioural features of the species. Collectively the new data necessitate taxonomic revision of the status of the species, viz: its removal from immediate association withM. mulatta (subgenusMaimon) and alignment within the subgenusZati. Zoogeographical discontinuity in this subgenus is compared with that of the subgenusSilenus.     

A note on the precision of estimates of gibberellin concentration from regression lines calculated from bioassay data

Summary The method by which the results of biological assays for gibberellinlike substances in plants are presented as gibberellic acid equivalents is discussed and a technique for deriving confidence limits for such estimates is referred to. Two different assay methods used to illustrate the technique both showed the relatively wide confidence limits associated with estimates of this kind, following the necessary logrithmic transformation of the data.     

Phosphotransferase system of Staphylococcus aureus: its requirement for the accumulation and metabolism of galactosides

The phosphotransferase system of Staphylococcus aureus was characterized. Mutants defective in enzyme I and heat-stable (HPr) protein as well as in the two components specific to lactose accumulation, factor III and enzyme II, were isolated. Colorimetric assays for each of the components are presented based on the formation of o-nitrophenyl-beta-d-galactoside-6-phosphate by the system and its hydrolysis by the staphylococcal 6-phospho-beta-galactosidase. The components were partially purified and their molecular weights were estimated: enzyme I, 100,000 +/- 15%; HPr, 10,000 +/- 15%; factor III, 30,000 +/- 15%; 6-phospho-beta-galactosidase, 45,000. Enzyme II is a membrane-bound protein.