Effect of aluminium on some properties and template activity of purified pea DNA

In order to study the mechanism of aluminium(Al)-induced inhibitionof root elongation, DNA was purified from Alaska pea seedlingsand some physical properties and template activity supportedby E. coli RNA polymerase were measured in the presence of Al.The absorption spectrum of the DNA did not shift, indicatingthat Al might bind to the DNA phosphate. While the Tm (meltingtemperature) of DNA was not affected by Al, the rate of hyperchromicitywas reduced with increasing concentrations of Al. The templateactivity of the DNA was clearly suppressed by the amount ofAl which was needed for the reduction of hyperchromicity. (Received September 9, 1977; )     

Oblique cell plate formation in tobacco BY-2 cells originates in double preprophase bands

Under specific experimental conditions, the formation of oblique cell plates was observed in tobacco BY-2 cells. Examination of this process, using an inverted microscope and immunofluorescence microscopy, revealed that the oblique cell plates were formed in cells that had double preprophase bands (PPBs). The formation of the oblique cell plates is discussed with a relationship to PPBs.     

Synthesis and Biochemical Activity of 5-Tethered Carborane-Containing Pyrimidine Nucleosides as Potential Agents for DNA Incorporation

Abstract

Synthesis and biochemical evaluation of a series of 5-tethered carborane-containing pyrimidine nucleosides have been undertaken. The biochemical studies with human TK demonstrated that these compounds can be phosphorylated to the corresponding 5′-monophosphate and that the most significant conversion occurred when seven atoms were inserted between the carborane cage and the pyrimidine base, and of these the best was the one with saturated ester.     

A de novo designed 11 kDa polypeptide: Model for amyloidogenic intrinsically disordered proteins

A de novo polypeptide GH₆[(GA)₃GY(GA)₃GE]₈GAH₆ (YE8) has a significant number of identical weakly interacting β‐strands with the turns and termini functionalized by charged amino acids to control polypeptide folding and aggregation. YE8 exists in a soluble, disordered form at neutral pH but is responsive to changes in pH and ionic strength. The evolution of YE8 secondary structure has been successfully quantified during all stages of polypeptide fibrillation by deep UV resonance Raman (DUVRR) spectroscopy combined with other morphological, structural, spectral, and tinctorial characterization. The YE8 folding kinetics at pH 3.5 are strongly dependent on polypeptide concentration with a lag phase that can be eliminated by seeding with a solution of folded fibrillar YE8. The lag phase of polypeptide folding is concentration dependent leading to the conclusion that β‐sheet folding of the 11‐kDa amyloidogenic polypeptide is completely aggregation driven. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 607–618, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

Hormonal Control of Elongation of Tobacco Cells Derived from Protoplasts

Spherical protoplasts (30–40 µm in diameter), isolatedfrom cultured tobacco cells, elongated rapidly during a cultureperiod of 3 to 8 days and finally assumed a long cylindricalform (300–400 µm in length). The optimum concentrationof a-naphthaleneacetic acid and benzyladenine for the elongationwas 0.1 mg/liter and 1 mg/liter respectively. (Received August 10, 1982; Accepted November 12, 1982)     

Prolactin augments luteinizing hormone binding to rat Leydig cells in serum-free culture

Effect of prolactin on the testicular luteinizing hormone binding was studied in a serum-free culture system. By the collagenase digestion of decapsulated testes taken out from 25-day-old rats, Leydig cells were isolated and cultured for 7 days in DME/F12 (1:1) medium supplemented with insulin, transferrin, epidermal growth factor, and gentamicin. The cultured cells exhibited the 3β-hydroxysteroid dehydrogenase activity. Hill plots constructed from the data of competition experiment showed that the dissociation constant (K_d) was 0.33 × 10^–10M. The K_d value was approximately the same as the known value for the rat testicular homogenates. When the Leydig cells were cultured with ovine prolactin for the last 3 days of 7-day culture period, the binding of luteinizing hormone increased to 1.7-fold ofthat in the control group. From these results it is concluded that prolactin acts to up-regulate the binding of luteinizing hormone to rat testicular Leydig cells in serum-free culture     

Less involvement of pectin, in the precipitatiro of aluminium in pea root

The possibility of absorbed aluminium (Al) associating withpectin in Alaska pea root was investigated. No distinct associationwas observed after gel filtration of the pectinase-digestedcell wall materials. Furthermore, partially overlapping Al anduronic acids eluted by gel filtration were not associated witheach other according to paper chromatography, paper electrophoresisand charging to Dowex 1 resin. Also there was no positive interrelationshipbetween the amounts of Al and uronic acids in three differentroot sections. The precipitation of a large amount of Al onthe root or root cell surface might have been caused by polymerizationof the absorbed monomeric Al due to pH increase in the root. (Received September 17, 1976; )     

Role of Sex Steroids on the Survival, Neuritic Outgrowth of Neurons, and Dopamine Neurons in Cultured Preoptic Area and Hypothalamus

Morphological sex differences in some discrete brain regions are thought to be developed by the influence of circulating androgen during the perinatal period. In order to know whether the effect of androgen is a direct one, cells derived from neonatal rat preoptic area (POA) and/or hypothalamus were cultured in a serum-free medium, and the effects on survival, process growth of neurons, and dopaminergic function were examined. When the POA cells were exposed to testosterone (T), neuronal survival was greater than the controls, and the frequency distribution of total process length and the number of process branchings were significantly deviated from the controls. Estradiol-17β (E₂) and 5α-dihydrotestosterone had less significant effects on these parameters than T. Moreover, the addition of T increased the dopamine (DA) contents of cells and medium DA in the hypothalamic culture. E₂ also greatly increased DA content of the medium. These steroids failed to alter the DA levels in the POA cell cultures. These results generally conform to the notion of previous investigators that T has direct effects on the expansion of dendritic elements of the POA and the development of sex difference in the hypothalamic DA neurons, although the effect of T after conversion to E₂ cannot be excluded.