Heterocycles from saccharide hydrazones : Part I. Saccharide 1,3,4-oxadiazoles

Oxidation, with iodine-mercuric oxide, of acetylated saccharide aroylhydrazones and of aromatic aldehyde hydrazones yields 5-aryl-2-(polyacetoxyalkyl)-1,3,4-oxadiazoles and 2,5-diaryl-1,3,4-oxadiazoles, respectively. On de-O-acetylation, saccharide oxadiazole acetates rearrange to the tautomeric, cyclic iminolactones which, on reacetylation, regenerate the starting oxadiazoles. Attempted dehydration of saccharide acetyl- and benzoyl-hydrazones by treatment with boiling acetic anhydride under reflux resulted in the formation of peracetylated N,N-diacetylhydrazones and-N-acetyl-N-benzoylhydrazones, respectively.     

Immobilization antigens of Tetrahymena pyriformis : I. Assay and extraction

A method using immunodiffusion has been established to assay the two mutually exclusive temperature dependent immobilization antigens, H and T, of Tetrahymena pyriformis. Specific antiserum was obtained by exploitation of allelic or temperature induced variations among inbred strains for absorption of antisera prepared against whole cells. The antigens were extracted both from isolated cilia and from whole cell bodies. Mild detergent extraction was found to be more efficient than mechanical disruption of the cells by freeze-thawing. The sedimentation behavior in sucrose density gradients of active H antigen was the same, whether freeze-thaw or detergent extracted; similarly, the sedimentation behavior of T was the same following the two extraction methods. Extraction with acetic acid, as reported by others, solubilized the same material as the detergent, but the acid denatured the antigen. An estimate of the molecular weight of the antigen of 29 000 for H and 23 000 for T was made.     

Light scattering by cellulose : IV. Fibers with helical morphology

Solid-state light scattering has been used to study the scattering by the helically wound microfibrils in wood fibers. Scattering envelopes have been recorded from a section of Eastern spruce wood as well as a single fiber of Black spruce. Theoretical expressions for the intensity of light scattered by a continuous helix have been derived and found to be in fair agreement with the experimental results. A method of estimating the “pitch” and “tilt” of the helical segments is outlined.     

Sub-lethal autolysis : Modification of cell periphery by lysosomal enzymes

Lysosomal activation was induced in dog kidney and HEp-2 cells by treatment with anticellular serum and high concentrations (20 μg/ml) of vitamin A alcohol. The morphological changes accompanying the release of enzymes from activated lysosomes were described. Measurements of cell coat thickness by ellipsometry revealed that lysosomal enzymes released extracellularly were able to digest the coat. The scale of enzyme release was an important factor in determining the amount of coat digested. Complement-sufficient anticellular sera and high concentrations of vitamin A induced marked lysosomal activation and extensive digestion of the coat. Complement-deficient anticellular serum produced significantly less lysosomal labilization and only limited digestion of the coat. The digestion of the cell coat induced by these agents was prevented by pretreatment of the cells with either hydrocortisone or chloroquine.     

Fluorinated carbohydrates : Part XIII. 2-deoxy-2-fluoro-D-galactose

Reaction of trifluoro(fluoroxy)methane at ca. −80° with 3,4,6-tri-O-acetyl-D-galactal affords trifluoromethyl 3,4,6-tri-O-acetyl-2-deoxy-2-fluoro-α-D-galactopyranoside (2, 39%), 3,4,6-tri-O-acetyl-2-deoxy-2-fluoro-α-D-galactopyranosyl fluoride (3, 37%), trifluoromethyl 3,4,6-tri-O-acetyl-2-deoxy-2-fluoro-α-D-talopyranoside (4, 3%), and 3,4,6-tri-O-acetyl-2-deoxy-2-fluor-α-D-talopyranosyl fluoride (5, 2%). The structures of compounds 2–5 have been established by n.m.r. spectroscopy. Acid hydrolysis of 2 or 3 allords 2-deoxy-2-fluoro-D-galactose.     

Intracellular pH electrode : Experiments on the giant squid axon

A new, easy method to produce and calibrate a 1-μm tip intracellular pH electrode is described. This antimony electrode and a micro-calomel electrode were inserted into the giant axon of Loligo pealii. The potential obtained when the axon was bathed in seawater corresponded to a pH of 7.0 ± 0.2. It was found that acidification of the external perfusate induced a drop in axoplasmatic pH leading to changes in the membrane electrical properties. Changes of resting or action potentials did not influence intracellular pH.     

Quinacrine fluorescence of metaphase chromosomes : Identical patterns in different tissues

The quinacrine mustard fluorescence patterns of the metaphase chromosomes of different tissues of the same plant species were found to be identical. Similar studies of the chromosome regions on human material gave the same result.     

Studies on purified α-actinin : I. Effect of temperature and tropomyosin on the α-actinin/F-actin interaction

α-Actinin, purified by two passages through a DEAE-cellulose column, migrates either as a single band or as a single major band with a fainter trailing band during polyacrylamide gel electrophoresis at pH 8.3. In the presence of sodium dodecyl sulfate, purified α-actinin always migrates as a single electrophoretic zone during polyacrylamide gel electrophoresis. Temperature has large effects on the interaction of α-actinin with F-actin. At 0 °C, α-actinin causes large increases in F-actin viscosity, either in the presence or absence of tropomyosin. Quantitative binding studies show that α-actinin can displace tropomyosin from F-actin at 0 °C and that F-actin will quantitatively bind 45% of its weight of α-actinin either in the presence or absence of tropomyosin. This binding ratio corresponds to one α-actinin molecule to approximately 10 to 11 G-actin subunits and suggests that one molecule of α-actinin binds to each turn of the F-actin helix at 0 °C.     

Deletion mutants of bacteriophage lambda : III. Physical structure of att

Deletion mutants and substitution mutants of bacteriophage λ have been used to examine the physical structure of the att^φ site in the λ chromosome which is essential for prophage integration. Integration-defective att mutants were analyzed by constructing heteroduplex DNA molecules containing one wild-type and one mutant strand and examining these heteroduplexes by electron microscopy. The results indicate that att^φ is less than 2500 base pairs in length and may be as small as 20 to 50 base pairs. Integration cross-overs between att^φ and its bacterial analog, att^B, occur within a region which is less than 12 base pairs in length. Moreover, there is no detectable base sequence homology between att^φ and att^B. These results suggest that λ integration is a truly unique system of recombination.     

Filamentous bacterial viruses : I. DNA synthesis during the early stages of infection with fd

During the first ten minutes after infection of bacteria with fd, the rate of DNA synthesis in an infected culture becomes several-fold larger than the rate in a parallel uninfected culture. This stimulation of rate is due to the synthesis of 100 to 200 double-stranded forms of viral DNA, superimposed on continuing bacterial DNA synthesis. At the end of the ten-minute period, the rate of viral plus bacterial DNA synthesis stops increasing, and remains constant for the next 50 minutes. The abrupt decrease in acceleration of net DNA synthesis corresponds in time to the onset of synthesis of single-stranded viral DNA.