Effect of chain length and concentration of anionic surfactants on the conformational transitions of poly(L-ornithine) and poly(L-lysine) in aqueous solution

The conformation of poly(L-ornithine) (PLO) and poly(L-lysine) (PLL) in solutions of sodium alkyl sulfates, CH₃(CH₂)_nSO₄Na with n = 7, 9, 11, 13 and 15 was studied by circular dichroism. PLO adopts a helical conformation in all 5 homologs and PLL a β-form in only 4 of the homologs. With octyl sulfate PLL has a helical conformation instead. These conformations were observed in solution of surfactants both below and above the critical micelle concentration.     

Gas-liquid chromatographic analysis of cyasin in cycad flour

A method for the quantitative determination of cycasin from cycad flour by gas-liquid chromatography is described. The flour is extracted with 70% ethanol and the residue from the dried extract is directly trimethylsilylated. Androsterone was found to be an excellent internal standard. The average content of cycasin from ten separate analyses of one lot of flour was $\text{0.429 gm}\text{100 gm}$. The method is rapid, sensitive, and not hindered by contaminating compounds.     

Characterization and Stability of Ribosomes from Mesophilic and Thermophilic Bacteria

Ribosomes were isolated from three mesophilic and three thermophilic strains of Bacillus. The ribosomes consisted of about 55% protein and 45% ribonucleic acid. Average ratios for the absorbance at 260/235 and 260/280 mmu were 1.77 and 1.92 for the mesophiles and 1.63 and 1.84 for the thermophiles. Ultracentrifugation revealed mainly components with sedimentation coefficients of about 30, 50, 70, 100, and 120S. All the preparations were shown to contain a ribonuclease which, in the presence of ethylenediaminetetraacetic acid, led to ribosome breakdown as measured by the increase in acid-soluble nucleotides. The stability of the ribosomes from the thermophiles was consistently greater than that of the ribosomes from the mesophiles. After 5 hr at 37 C, the breakdown was about 80% for the ribosomes from the mesophiles and 55 to 70% for those from the thermophiles. At 60 C, the ribosomes from the mesophiles were broken down slightly more and at a faster rate than those from the thermophiles. At temperatures above 60 C, the breakdown was again more pronounced for the ribosomes from the mesophiles.     

Differing activities of medullary respiratory neurons in eupnea and gasping

Our purpose was to compare further eupneic ventilatory activity with that of gasping. Decerebrate, paralyzed, and ventilated cats were used; the vagi were sectioned within the thorax caudal to the laryngeal branches. Activities of the phrenic nerve and medullary respiratory neurons were recorded. Antidromic invasion was used to define bulbospinal, laryngeal, or not antidromically activated units. The ventilatory pattern was reversibly altered to gasping by exposure to 1% carbon monoxide in air. In eupnea, activities of inspiratory neurons commenced at various times during inspiration, and for most the discharge frequency gradually increased. In gasping, the peak discharge frequency of inspiratory neurons was unaltered. However, all commenced activities at the start of the phrenic burst and reached peak discharge almost immediately. The discharge frequencies of all groups of expiratory neurons fell in gasping, with many neurons ceasing activity entirely. These data are consistent with the hypothesis that brain stem mechanisms controlling eupnea and gasping differ fundamentally.