Hormones andCuscuta development: interaction of cytokinin and indole-3-acetic acid in the growth and curvature of subapical stem segments

Cuscuta stem (vines) exhibits two modes of growth—longitudinal elongation forming free-hanging vines, or coiling growth to twine around the host. The elongation zone of free-hanging vine extended up to 160 mm from the stem apex and in vivo growth rate (during 8 h of growth) was maximal in the 20-to-40-mm region. While gibberellic acid (GA3) or fusicoccin (FC) could maintain (GA3) or enhance (FC) the growth rate of apical (10 or 25 mm) segments, indole-3-acetic acid (IAA) (10 mgrM) induced growth only in subapical (5–160 mm) segments. In vitro growth rate induced by IAA (10 mgrM) was similar to the in vivo growth rate up to 40 mm. Thereafter, up to 100 mm, IAA induced growth rate exceeded in vivo growth. p ]Subapical segments (sim13 mm) from 5- to 40-mm regions responded to a cytokinin (BA, Z, or iP) or to low IAA (0.1 mgrM) with curved growth, whereas the segments grew straight in the presence of high IAA (10 mgrM). Curvature (measured as the angle subtended at the center of the circle of which the segment formed an arc) induced by BA and low (0.1 mgrM) IAA was greater than either added separately. Besides, segments induced to curve in BA + low-IAA solution could be made to straighten out by transferring to a solution containing high IAA (10 mgrM) with or without BA. Thus in vivo patterns of straight and coiling growth could be mimicked reversibly in vitro by adjusting the relative concentrations of cytokinin and auxin; low auxin and cytokinin induced coiling growth, whereas high auxin and cytokinin induced straight growth. p ]Beyond 40 mm, BA had no growth-promoting or curvative-inducing effect.Cuscuta vine segments thus showed sequential sensitivity to applied hormones, the apical region (0–25 mm) to GA3, the subapical (5–40 mm) region to BA and IAA and the region beyond (40–160 mm) to IAA alone.

Superharmonic vibrations of order 3 in stretched strings

Superharmonic vibrations of order 3 in stretched strings driven by a single-mode planar simple-harmonic force are investigated. It is shown that planar as well as nonplanar superharmonic resonances can occur. After giving a few analytical results, the problem is thoroughly investigated numerically. The stability analysis shows that the region of stable nonplanar oscillations is much smaller than that of stable planar oscillation. It is observed in the case of nonplanar oscillations that the amplitude of the superharmonic in the plane normal to the plane of excitation is larger than that in the plane of excitation.

Purification and properties of 4-hydroxyphenylacetic acid 3-hydroxylase from pseudomonas putida

4-Hydroxyphenylacetic acid 3-hydroxylase is a key enzyme in the pathway for the microbial degradation of phenylalanine, tyrosine and many aromatic amines. This enzyme was purified to homogeneity from Image by affinity chromatography. The protein had a molecular weight of 91,000 and was a dimer of identical subunits. It was a typical external flavoprotein monooxygenase and showed an absolute requirement of NADH for activity. The enzyme had a pH optimum of 7.5 and the Km values for 4-hydroxyphenylacetic acid and NADH were 2×10−4 M and 5.9×10−5 M respectively. It was strongly inhibited by heavy metal ions and thiol reagents, suggesting the possible involvement of -SH group(s) in enzyme reaction.

Crystal structure of 8-methoxy-3-dibromoacetylcoumarin, C12H8Br2O4

C12H8BT2O4. monoclinic, P12(1)/cl (No. 14), a = 11.546(2) Angstrom, b = 6.885(4) Angstrom,= 15.949(3) Angstrom, beta = 101.75(2)degrees, V= 1241.3 Angstrom(3), Z = 4, p(m) = 2.040 g.cm(-3), R-all(F) = 0.039, wR(all)(F) = 0.043, T = 300 K.

Design and fabrication of an automated temperature programmed reaction system to evaluate 3-way catalysts Ce1-x-y(La/Y)(x)PtyO2-delta

A completely automated temperature-programmed reaction (TPR) system for carrying out gas-solid catalytic reactions under atmospheric flow conditions is fabricated to study CO and hydrocarbon oxidation, and NO reduction. The system consists of an all-stainless steel UHV system, quadrupole mass spectrometer SX200 (VG Scientific), a tubular furnace and micro-reactor, a temperature controller, a versatile gas handling system, and a data acquisition and analysis system. The performance of the system has been tested under standard experimental conditions for CO oxidation over well-characterized Ce1-x-y(La/Y)(y)O2-delta catalysts. Testing of 3-way catalysis with CO, NO and C2H2 to convert to CO2, N-2 and H2O is done with this catalyst which shows complete removal of pollutants below 325 degrees C. Fixed oxide-ion defects in Pt substituted Ce1-y(La/Y)(y)O2-y/2 show higher catalytic activity than Pt ion-substituted CeO2.

Structural and spectral perspectives of a novel thiosemicarbazone synthesized from di-2-pyridyl ketone and 4-phenyl-3-thiosemicarbazide

A new thiosemicarbazone, HL is synthesized from di-2-pyridyl ketone and 4-phenyl-3-thiosemicarbazide and structurally and spectrochemically characterized. H-1 NMR, C-13 NMR, COSY, HMQC and IR spectra of the compound are studied and the proton magnetic resonance spectrum reveals some unprecedented observations. The thione form is predominant in the solid state, as supported by the crystal structure and IR data, while a thiol-thione equilibrium is proposed in the solution state by NMR studies. The compound crystallizes into a monoclinic lattice with space group C2/c and the ZE conformation is exhibited by the thiosemicarbazone. Intra- and intermolecular hydrogen-bonding interactions give rise to a two-dimensional packing in the crystal lattice. (c) 2005 Elsevier B.V. All rights reserved.

Proton-bifurcated C-H center dot center dot center dot(O,O) hydrogen bonds in 2,3-dichloro-6-nitrobenzylaminium chloride

In the crystal structure of the title salt, C7H7Cl2N2O2+ center dot Cl-, the chloride anions participate in extensive hydrogen bonding with the aminium cations and indirectly link the molecules through multiple N+-H center dot center dot center dot Cl- salt bridges. There are two independent molecules in the asymmetric unit, related by a pseudo-inversion center. The direct intermolecular coupling is established by C-H center dot center dot center dot O, C-H center dot center dot center dot Cl and C-Cl center dot center dot center dot Cl- interactions. A rare three-center (donor bifurcated) C-H center dot center dot center dot (O,O) hydrogen bond is observed between the methylene and nitro groups, with a side-on intramolecular component of closed-ring type and a head-on intermolecular component.