Effect of High-intensity Light Given Prior to Low-temperature Treatment on the Long-day Flowering of Pharbitis nil

Pharbitis nil, strain Violet which had been exposed to high-intensitylight (18,000 lux at 23?C) for 7 days followed by a low-temperaturetreatment (13–14?C) for 7 days initiated flower buds evenunder continuous light, but plants given these treatments inreverse order failed to bud. Three days of high-intensity lightat 23?C was most effective in promoting the flower-inducingeffect of the subsequent low-temperature period. Six days oflow temperature following the 3-day high-intensity light periodinduced near-maximum flowering response. DCMU (5?10^–6M) given during the high-intensity light period inhibited flowering,but when given during or after the low-temperature period itwas ineffective. DCMU at the same concentration given before,during or after an inductive 16-hr dark period at 26?C did notinhibit flowering. Sucrose, ATP, NADPH and some other reducingagents tested did not nullify the DCMU effect nor substitutefor the effect of high-intensity light. But, the high-intensitylight effect could be substituted, at least partly, by 5-chlorosalicylicacid, 3,4-dichlorobenzoic acid and some other benzoic acid derivatives,which are highly effective in inducing long-day flowering inthe short-day plant, Lemna paucicostata. (Received October 20, 1981; Accepted February 3, 1982)     

Molecular adaptability of carp myosin: a study of some physico-chemical properties and their comparison with those of rabbit myosin.

During thermal inactivation, the addition of as low as M urea resulted in the reduction of delta G identical to barrier of the inactivation of carp myosin Ca2+-ATPase, whereas that of rabbit myosin remained unaffected. In the absence of urea, a four-hour incubation of carp myosin was accompanied by the release of light chains at 30 degrees C, a value 10 degrees C lower than that for rabbit myosin. Electron micrographs revealed that carp myosin forms artificial thick filaments, which were uniform in size and may differ in a few details from those of rabbit. Not only that helical content of carp myosin was about 4% less than those of rabbit myosin, but it showed more sensitivity to thermal and urea denaturation; and its reversibility upon subsequent cooling or removal of urea was rather poor. The loss in helicity of myosins by urea was a concentration- and temperature-dependent biphasic reaction, with the most obvious effect observed on carp myosin. That carp myosin has increased tendency of unfolding in urea solutions was confirmed by viscosity data and the exposure of thiols also. Even in the absence of urea more SH groups of carp myosin were incorporated by DTNB, and more epsilon-amino groups reacted with NQS. Carp myosin remained in solution till the modification of about 52 surface myosin remained in solution till the modification of about 52 surface amino groups, whereas no precipitation effect was noted in case of rabbit myosin. Neither amino-acid composition nor some parameters derived from it, such as average hydrophobicity polarity index and number of polar side chains, revealed any difference pertinent to the relative stability of the two myosins. On the contrary, the contractile efficiency of carp myosin in the near physiological range was high and thus inversely related with the thermostability. This relationship along with the above evidence has been regarded to demonstrate the adaptability of carp myosin through a loose molecular conformation, which has probably been achieved by the addition of weak interactions in the course of evolution.     

Production of L-aspartic acid from fumaric acid by a fumaric acid-assimilating obligate thermophile,Bacillus stearothermophilus KP 1041

Summary A fumaric acid-assimilating obligate thermophile having a high aspartase activity was isolated from soil. The isolate (KP 1041) that grew at 45 to 68 °C was assigned to a strain of Bacillus stearothermophilus. The cell suspensions produced L-aspartate from fumarate and ammonium ion, with the rapidest initial rate at 65 °C and pH 9.5. The Michaelis constant for fumarate was 0.2 M. The cellular aspartase was relatively stable for 18 h at and below 50 °C over a pH range 6.7–8.3 in the presence of ammonium fumarate; this substance protected the enzyme from heat inactivation. The best yield in L-aspartic acid production was achieved at 6 h incubation at 53 °C and pH 8.5, using 0.88 M fumarate, 3.1 M ammonium ion, and the cells at 53 mg dry weight per ml. In this case, 85% of fumarate added was converted into aspartic acid. The structure of the product was determined from its infrared spectrum, specific rotation, melting point and ultimate analysis.Presented at the Annual Meeting of the Agricultural Chemical Society of Japan, Yokohama, April 2, 1977     

Electron paramagnetic resonance properties and oxidation-reduction potentials of the molybdenum,flavin, and iron-sulfur centers of chicken liver xanthine dehydrogenase

The oxidation-reduction potentials of the various prosthetic groups in the native and desulfo forms of chicken liver xanthine dehydrogenase, determined by potentiometric titration in 0.05 m potassium phosphate buffer, pH 7.8, are: Mo(VI)/Mo(V) (native), ?357 mV; Mo(VI)/Mo(V) (desulfo), ?397 mV; Mo(V)/Mo(IV) (native), ?337 mV; Mo(V)/Mo(IV) (desulfo), ?433 mV; FAD/FADH · ?345 mV; FADH · FADH₂, ? 377 mV; (Fe/S)I_ox/(Fe/S)I_red, ?280 mV; (Fe/S)II_ox/(Fe/S)II_red, ? 275 mV. Titration at pH 6.8 revealed that the Mo and FAD centers but not the Fe/S centers are in prototropic equilibrium. Spectroscopic studies on the native and deflavinated enzymes show that environment of the flavin in xanthine dehydrogenase differs from that in bovine milk xanthine oxidase.     

Differential effects of oxygen on N2 fixation and C2H2 reduction by Anabaena cylindrica

Both nitrogen fixation and acetylene reduction by intact cellsof Anabaena cylindrica were inhibited by oxygen, but nitrogenfixation was invariably less sensitive than acetylene reduction.The C₂H₂/N₂ ratio ranged from 6 to 8 in the absence of oxygen,and it decreased with increase in partial pressure of oxygento 2 at a pO₂ of 0.3 atm. (Received June 5, 1979; )     

Prevention by Vitamin A of the occurrence of permanent vaginal changes in neonatally estrogen-treated mice

Cell and Tissue Research - Ovary-independent (estrogen-independent) irreversible proliferation and cornification of the vaginal epithelium in ovariectomized mice caused by neonatal injections of 20...