A rapid, simple determination of plasma cyclic AMP

Plasma cyclic AMP content was determined without being extracted, using binding protein obtained from rat liver. EDTA was suitable as an anticoagulant for cyclic AMP estimation. Cyclic AMP further added to EDTA plasma was able to be estimated. The estimated values by plasma dilution were almost the same as the expected values. It was thought that the direct assay was useful for determination of plasma cyclic AMP. Isoproterenol (50 microgram/kg, iv) produced an increase of plasma cyclic AMP level accompanied with a decrease of blood pressure and an increase of heart rate in anesthetized dogs. Cyclic AMP level of peripheral venous plasma was 18.6 +/- 1.32 p mole/ml in human (N=25), 21.6 +/- 3.04 P mole/ml in dogs (N=7) and 50.6 +/- 4.59 p mole/ml in rabbit (N=9). Plasma cyclic AMP level of rabbit was higher than those of human and dog.

The use of tris-HCl buffer for inoculation of tomato protoplasts with tobacco mosaic virus

When tris-HCL was used as the buffer for inoculation of tomato protoplasts with tobacco mosaic virus, a greater proportion became infected than when phosphate was used. Using 0-05 M-tris-HCl buffer, pH 8-0, in the presence of poly-L-ornithine or poly-D-lysine, 50 to 80 % infection was obtained.

Mechanism determining the host specificity of tobacco mosaic virus. I. Formation of polysomes containing infecting viral genome in various plants

In order to know the mechanism controling the host specificity of tobacco mosaic virus (TMV), three species of plants showing various degrees of resistance to TMV or TMV‐RNA infection were selected and the fate of infecting viral genome was studied. Extract was obtained from leaves 0.5–6 hr after inoculation of 32P‐TMV or 32P‐TMV‐RNA and analyzed by sucrose density gradient centrifugation. It was found that polysomes containing infecting 32P‐RNA were formed in plants resistant to TMV to the same extent as in susceptible tobacco plants, suggesting that the host specificity of TMV is determined at a stage of viral multiplication later than the step of translation of infecting viral genome.

Multiplication of tobacco mosaic virus in suspension culture of tobacco cells

The present study was attempted to establish an in vitro system for TMV infection and multiplication. A friable cell line Bf1 was isolated from an original callus line which which obtained from a pith of Nicotiana tabacum. Cells of the line were stirred with ordinary TMV by means of a grass rod to be mechanically infected, suspended in the liquid medium, and incubated on a reciprocal shaker. Infectivity of TMV in the cells was determined by the local lesion assay with the leaves of N. glutinosa. It was increased in the incubated cells, reflecting that TMV was able to multiply in the in vitro system. An exponential increase of infectivity was observed during 2 and 5 days after inoculation.