[Show abstract][Hide abstract] ABSTRACT: We report dynamic regimes supported by a sharp quasi-one-dimensional (1D) ("razor"), pyramid-shaped ("dagger"), and conical ("needle") potentials in the 2D complex Ginzburg-Landau (CGL) equation with cubic-quintic nonlinearity. This is a model of an active optical medium with respective expanding antiwaveguiding structures. If the potentials are strong enough, they give rise to continuous generation of expanding soliton patterns by a 2D soliton initially placed at the center. In the case of the pyramidal potential with M edges, the generated patterns are sets of M jets for M < or = 5, or expanding polygonal chains of solitons for M > or = 6. In the conical geometry, these are concentric waves expanding in the radial direction.
[Show abstract][Hide abstract] ABSTRACT: We find that the angle between elementary lattice vectors obviously affects the bandwidth and dispersion of slow light in photonic crystal line-defect waveguides. When the fluctuation of group index is strictly limited in a +/-1% range, the oblique lattice structures with the angle between elementary lattice vectors slightly larger than 60 degrees have broader available bandwidth of flat band slow light than triangular lattice structures. For example, for the angle 66 degrees , there are increases of the available bandwidth from 20% to 68% for several different structures. For the same angle and a +/-10% variation in group velocity, when group indices are nearly constants of 30, 48.5, 80 and 130, their corresponding bandwidths of flat band reach 20 nm, 11.8 nm, 7.3 nm and 3.9 nm around 1550 nm, respectively. The increasing of bandwidth is related to the shift of the anticrossing point towards smaller wave numbers.
[Show abstract][Hide abstract] ABSTRACT: Annularly and radially phase-modulated spatiotemporal necklace-shaped patterns (SNPs) in the complex Ginzburg-Landau (CGL) and complex Swift-Hohenberg (CSH) equations are theoretically studied. It is shown that the annularly phase-modulated SNPs, with a small initial radius of the necklace and modulation parameters, can evolve into stable fundamental or vortex solitons. To the radially phase-modulated SNPs, the modulated "beads" on the necklace rapidly vanish under strong dissipation in transmission, which may have potential application for optical switching in signal processing. A prediction that the SNPs with large initial radii keep necklace-ring shapes upon propagation is demonstrated by use of balance equations for energy and momentum. Differences between both models for the evolution of solitons are revealed.
[Show abstract][Hide abstract] ABSTRACT: We have cloned a chitinase cDNA (MpChi-1) from plantain (Musa paradisiacal L) using rapid amplification of cDNA ends (RACE) according to a sequence fragment which we had cloned using the suppression subtractive hybridization (SSH) technique. The MpChi-1 encodes a protein of 326 amino acids and belongs to acidic chitinase class Ib subfamily. MpChi-1 shares high identity with rice endochitinase (XP_468714) and different each other only at three residues. Homology modelling indicated these three substitutions would not change the configuration of the activity site of the enzyme. We have expressed recombinant MpChi-1 and purified by ammonium sulphate precipitation and preparative reversed phase HPLC. The recombinant protein could hydrolyse chitin and inhibit the growth of the Gloeosporium musarum Cke and Massee in vitro. Northern blot revealed that the MpChi-1 transcripts rapidly after inoculation with G. musarum and maximum mRNA accumulation reached at 48 h. Jasmonic acid (JA) and salicylic acid (SA) could induce MpChi-1 expression, while mechanical wounding, silver nitrate and osmotic stress stimulated only a slight accumulation of MpChi-1 transcripts. Abscisic acid (ABA) could induce MpChi-1 transcript. These results suggest the MpChi-1 plays important role in the events of the hypersensitive reaction (HR).
Preview · Article · Dec 2007 · Journal of Biochemistry
[Show abstract][Hide abstract] ABSTRACT: The carrot (Daucus carota) antifreeze protein (DcAFP) has a strong antifreeze activity and identified as belonging to the plant polygalacturonase-inhibiting protein (PGIP) family based on its sequence similarities, including the presence of a leucine-rich repeat (LRR) motif. In this study, yeast two-hybrid technology was used to analyze whether the carrot AFP could act as a PGIP. The complete DcAFP and polygalacturonase (PGase; obtained from fungus Alternaria alternata by RT-PCR) coding sequences were cloned into the bait and capture vectors, respectively, and yeast two-hybrid assays were performed. The results revealed that there was no evidence of an interaction between DcAFP and PGase, which suggests that DcAFP probably lacks PGIP activity. An analysis of the electrostatic potential of DcAFP and other PGIPs revealed that a large number of nonconservative residues within the beta-helix of the DcAFP LRR motif had been substituted to basic amino acids, thus changing the surface from negative to positive. This will electrostatically prevent DcAFP from binding with the positively charged surface of PGase. This is the first report that showed the correlation between nonconservative amino acids within the LRR motif of the DcAFP and its loss of polygalacturonase inhibiting activity.
Preview · Article · Dec 2006 · Acta Genetica Sinica