Assimilate partitioning in Pachyrhizus erosus tubers under short days

The distribution of ¹⁴C products in yam bean ( Pachyrhizus erosus ) plants was measured as a function of time after a ¹⁴CO₂ pulse-chase experiment under short-day conditions. The ¹⁴C declined by more than 70% in leaves during the first two hours, indicating that they actively exported carbon. Tubers were strong storage sinks for carbon and accumulated more than 80% of the total incorporated ¹⁴C after a 72-h chase. The data show that, although sucrose represented about 21% of the tuber non-structural carbohydate, i.e. 15% of the tuber dry weight, ¹⁴C did not accumulate in sucrose but in glucose, fructose and starch. The data indicate the existence of a separate sucrose pool which is affected only very slowly by recent assimilates. As a result, recent photosynthates, temporarily stored, may contribute to the reservoir of carbon available for nitrogen fixation. The data also suggest the existence of two distinct pools of amino acids in the tuber, one utilized mostly for protein synthesis and the other probably stored in the vacuole.     

Natural Messenger Ribonucleic Acid-Directed Cell-Free Protein-Synthesizing System of Bacillus subtilis

A very active in vitro protein-synthesizing system has been developed from Bacillus subtilis. High activity in the extracts is dependent upon precautions taken to reduce proteolytic activity. Endogenous, exogenous natural and synthetic messenger ribonucleic acids (RNAs) are translated by the system. The activity of the B. subtilis system has been compared to that of the Escherichia coli system. With either SPO1 RNA or polyuridylic acid, the activities of the two systems were very similar. Electrophoresis of the products synthesized in vitro by the two systems primed with SPO1 RNA yields similar radioactive profiles. The major bands of radioactivity correspond to proteins of molecular weight between 15,000 and 40,000.     

Cu(II)–Protamine interaction. I. The formation and structure of Cu(II)–clupeine Z complexes

The formation and structure of four different Cu(II)–clupeine Z complexes have been studied using potentiometric and spectroscopic (ir and visible absorption, and CD) measurements. The results thus obtained indicate the presence of up to 8 binding sites in the pH range from 6.5 to 10.5. The spectroscopic evidence suggests that the strongest site available contains the α-amino terminal and the adjacent peptide nitrogen, which bind to copper from pH 5 to 6.5 to form the first complex. The stability constant of this first complex has a value of (9.5 ± 0.9) × 10³ mol^?1 1. From pH 6.5 to 8.5, two intervening guanidinium nitrogens of arginine residues occupy the two other corners of the coordination square, giving rise to the second complex. The other sites potentially available from pH 6.5 to 10.5 are formed by two amino nitrogens of arginine residues and two contiguous peptide nitrogens. The first intervene up to pH 8.5, forming the third complex, and the latter from this pH to 10.5, forming the fourth complex. Although the ligands intervening at sites 2–8 appear to be the same, the sites are by no means equivalent. The spectroscopic data enable one to distinguish three different types of binding sites.     

Scanning Electron Microscopy of Invasion of Apple Leaves and Blossoms by Pseudomonas syringae pv. syringae

Scanning electron microscopy indicated that Pseudomonas syringae pv. syringae L795 entered leaves through stomata and multiplied in the substomatal chambers. Strain L195 applied to blossoms colonized stigmas and also occurred in intercellular spaces of styles. Nonpathogenic strain L796 failed to colonize blossoms. This study suggests that inoculum of pathogenic P. syringae pv. syringae builds up on apple leaves and blossoms.     

A microdilution method for drug sensitivity testing of fish associated bacteria at 22°C

When applied to the psychrophilic and psychrotropic bacteria associated with diseases of fish, the disc-diffusion method generally fails to provide correct estimates of minimal inhibitory concentrations (MIC). A microdilution method using a medium containing agar (15 g/l) and 10 selected drugs has been developed. Serial four-fold dilutions of the drugs were performed in specially designed dilution plates, which were prepared and stored at −30° or −70°C. Although its reliability sometimes appeared to be influenced by the temperature at the time of testing, the temperature and duration of freezing and the nature of the drugs, the microtest provided results as accurate as other reference methods. In repeated experiments very rare major discrepancies were noted and minor variations of one dilution step were below 10%, except with tetracyclines and the sulphonamide-trimethoprim mixture. The advantages of the method and the optimum conditions for use in fish disease diagnosis are specified.