349 research outputs found
Detection of gfp expression from gfp-labelled bacteria spot inoculated onto sugarcane tissues
Green fluorescent protein (GFP) as a marker gene has facilitated biological research in plant-microbe interactions. However, there is one major limiting factor in the detection of GFP in living organisms whose cells emit background autofluorescence. In this study, Herbaspirillum sp. B501gfp1 bacterial cells were spot inoculated onto 5 month-old sterile micro-propagated sugarcane tissues to detect if the GFP fluorescence expression could be distinguished from the tissue’s background fluorescence. Stem tissues and leaf sections mounted on glass slides were directly inoculated with a single touch using the tip of a syringe previously dipped into the inoculum containing 108 bacterial cells/ml. We observed that GFP fluorescence could be easily distinguished in the stem than in the leaf tissues. However, the brightness level of the fluorescence varied with time as a result of fluctuations in the bacterial celldensity. The presence of chloroplasts in the leaf tissues of sugarcane requires the use of bright GFP variants when monitoring bacteria-plant interactions using GFP labelled bacteria
Colonization ability of Herbaspirillum spp. B501gfp1 in sugarcane, a non-host plant in the presence of indigenous diazotrophic endophytes
Inoculating sugarcane with a mixture of diazotrophic endophytic bacteria has shown that they can provide substantial amount of biologically fixed nitrogen to the plant. The genera of diazotrophic endophytes previously isolated from sugarcane have been reported associating with other nonleguminousplants showing a broad host range. This study examined the colonization ability of a wild rice isolate, Herbaspirillum spp., in sugarcane plants in the presence of indigenous endophytes using two inoculum concentrations (102 and 108 bacterial cells ml-1). Internal tissue colonization was observed in plants inoculated with both the 102 and 108 B501gfp1 bacterial cells ml-1 inoculum concentrations. However, extensive colonization and higher bacterial numbers were determined only in the basal stem tissues of plants inoculated with the 108 bacterial cells ml-1
Scattering of Plane Waves in Self-Dual Yang-Mills Theory
We consider the classical self-dual Yang-Mills equation in 3+1-dimensional
Minkowski space. We have found an exact solution, which describes scattering of
plane waves. In order to write the solution in a compact form, it is
convenient to introduce a scattering operator . It acts in the direct
product of three linear spaces: 1) universal enveloping of Lie algebra,
2) -dimensional vector space and 3) space of functions defined on the unit
interval.Comment: 16 pages, LaTeX fil
Closed conformal Killing-Yano tensor and geodesic integrability
Assuming the existence of a single rank-2 closed conformal Killing-Yano
tensor with a certain symmetry we show that there exist mutually commuting
rank-2 Killing tensors and Killing vectors. We also discuss the condition of
separation of variables for the geodesic Hamilton-Jacobi equations.Comment: 17 pages, no figure, LaTe
Exact form factors for the scaling Z{N}-Ising and the affine A{N-1}-Toda quantum field theories
Previous results on form factors for the scaling Ising and the sinh-Gordon
models are extended to general -Ising and affine -Toda quantum
field theories. In particular result for order, disorder parameters and
para-fermi fields and are
presented for the -model. For the -Toda model all form factors
for exponentials of the Toda fields are proposed. The quantum field equation of
motion is proved and the mass and wave function renormalization are calculated
exactly.Comment: Latex, 11 page
Normalization of Off-shell Boundary State, g-function and Zeta Function Regularization
We consider the model in two dimensions with boundary quadratic deformation
(BQD), which has been discussed in tachyon condensation. The partition function
of this model (BQD) on a cylinder is determined, using the method of zeta
function regularization. We show that, for closed channel partition function, a
subtraction procedure must be introduced in order to reproduce the correct
results at conformal points. The boundary entropy (g-function) is determined
from the partition function and the off-shell boundary state. We propose and
consider a supersymmetric generalization of BQD model, which includes a
boundary fermion mass term, and check the validity of the subtraction
procedure.Comment: 21 pages, LaTeX, comments and 3 new references adde
Hermitian Yang-Mills instantons on resolutions of Calabi-Yau cones
We study the construction of Hermitian Yang-Mills instantons over resolutions
of Calabi-Yau cones of arbitrary dimension. In particular, in d complex
dimensions, we present an infinite family, parametrised by an integer k and a
continuous modulus, of SU(d) instantons. A detailed study of their properties,
including the computation of the instanton numbers is provided. We also explain
how they can be used in the construction of heterotic non-Kahler
compactifications.Comment: 20 pages, 1 figure; typos corrected, section 3.1 expande
Medaka: a promising model animal for comparative population genomics
<p>Abstract</p> <p>Background</p> <p>Within-species genome diversity has been best studied in humans. The international HapMap project has revealed a tremendous amount of single-nucleotide polymorphisms (SNPs) among humans, many of which show signals of positive selection during human evolution. In most of the cases, however, functional differences between the alleles remain experimentally unverified due to the inherent difficulty of human genetic studies. It would therefore be highly useful to have a vertebrate model with the following characteristics: (1) high within-species genetic diversity, (2) a variety of gene-manipulation protocols already developed, and (3) a completely sequenced genome. Medaka (<it>Oryzias latipes</it>) and its congeneric species, tiny fresh-water teleosts distributed broadly in East and Southeast Asia, meet these criteria.</p> <p>Findings</p> <p>Using <it>Oryzias </it>species from 27 local populations, we conducted a simple screening of nonsynonymous SNPs for 11 genes with apparent orthology between medaka and humans. We found medaka SNPs for which the same sites in human orthologs are known to be highly differentiated among the HapMap populations. Importantly, some of these SNPs show signals of positive selection.</p> <p>Conclusion</p> <p>These results indicate that medaka is a promising model system for comparative population genomics exploring the functional and adaptive significance of allelic differentiations.</p
Exact form factors in integrable quantum field theories: the sine-Gordon model (II)
A general model independent approach using the `off-shell Bethe Ansatz' is
presented to obtain an integral representation of generalized form factors. The
general techniques are applied to the quantum sine-Gordon model alias the
massive Thirring model. Exact expressions of all matrix elements are obtained
for several local operators. In particular soliton form factors of charge-less
operators as for example all higher currents are investigated. It turns out
that the various local operators correspond to specific scalar functions called
p-functions. The identification of the local operators is performed. In
particular the exact results are checked with Feynman graph expansion and full
agreement is found. Furthermore all eigenvalues of the infinitely many
conserved charges are calculated and the results agree with what is expected
from the classical case. Within the frame work of integrable quantum field
theories a general model independent `crossing' formula is derived. Furthermore
the `bound state intertwiners' are introduced and the bound state form factors
are investigated. The general results are again applied to the sine-Gordon
model. The integrations are performed and in particular for the lowest
breathers a simple formula for generalized form factors is obtained.Comment: LaTeX, 53 pages, Corrected typo
On the Classification of Brane Tilings
We present a computationally efficient algorithm that can be used to generate
all possible brane tilings. Brane tilings represent the largest class of
superconformal theories with known AdS duals in 3+1 and also 2+1 dimensions and
have proved useful for describing the physics of both D3 branes and also M2
branes probing Calabi-Yau singularities. This algorithm has been implemented
and is used to generate all possible brane tilings with at most 6
superpotential terms, including consistent and inconsistent brane tilings. The
collection of inconsistent tilings found in this work form the most
comprehensive study of such objects to date.Comment: 33 pages, 12 figures, 15 table
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