1,660 research outputs found
Gene Clusters Located on Two Large Plasmids Determine Spore Crystal Association (SCA) in Bacillus thuringiensis Subsp. finitimus Strain YBT-020
Crystals in Bacillus thuringiensis are usually formed in the mother cell compartment during sporulation and are separated from the spores after mother cell lysis. In a few strains, crystals are produced inside the exosporium and are associated with the spores after sporulation. This special phenotype, named ‘spore crystal association’ (SCA), typically occurs in B. thuringiensis subsp. finitimus. Our aim was to identify genes determining the SCA phenotype in B. thuringiensis subsp. finitimus strain YBT-020. Plasmid conjugation experiments indicated that the SCA phenotype in this strain was tightly linked with two large plasmids (pBMB26 and pBMB28). A shuttle bacterial artificial chromosome (BAC) library of strain YBT-020 was constructed. Six fragments from BAC clones were screened from this library and discovered to cover the full length of pBMB26; four others were found to cover pBMB28. Using fragment complementation testing, two fragments, each of approximately 35 kb and located on pBMB26 and pBMB28, were observed to recover the SCA phenotype in an acrystalliferous mutant, B. thuringiensis strain BMB171. Furthermore, deletion analysis indicated that the crystal protein gene cry26Aa from pBMB26, along with five genes from pBMB28, were indispensable to the SCA phenotype. Gene disruption and frame-shift mutation analyses revealed that two of the five genes from pBMB28, which showed low similarity to crystal proteins, determined the location of crystals inside the exosporium. Gene disruption revealed that the three remaining genes, similar to spore germination genes, contributed to the stability of the SCA phenotype in strain YBT-020. Our results thus identified the genes determining the SCA phenotype in B. thuringiensis subsp. finitimus
Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV
By analyzing the data sets of 17.3 pb taken at GeV
and 6.5 pb taken at GeV with the BESII detector at the
BEPC collider, we have measured the observed cross sections for 12 exclusive
light hadron final states produced in annihilation at the two energy
points. We have also set the upper limits on the observed cross sections and
the branching fractions for decay to these final states at 90%
C.L.Comment: 8 pages, 5 figur
Measurements of psi(2S) decays to octet baryon-antibaryon pairs
With a sample of 14 million psi(2S) events collected by the BESII detector at
the Beijing Electron Positron Collider (BEPC), the decay channels psi(2S)->p
p-bar, Lambda Lambda-bar, Sigma0 Sigma0-bar, Xi Xi-bar are measured, and their
branching ratios are determined to be (3.36+-0.09+-0.24)*10E-4,
(3.39+-0.20+-0.32)*10E-4, (2.35+-0.36+-0.32)*10E-4, (3.03+-0.40+-0.32)*10E-4,
respectively. In the decay psi(2S)->p p-bar, the angular distribution parameter
alpha is determined to be 0.82+-0.17+-0.04.Comment: 8 pages, 8 figure
Measurements of the observed cross sections for exclusive light hadrons containing at , 3.650 and 3.6648 GeV
By analyzing the data sets of 17.3, 6.5 and 1.0 pb taken,
respectively, at , 3.650 and 3.6648 GeV with the BES-II
detector at the BEPC collider, we measure the observed cross sections for
, , ,
and at the three energy
points. Based on these cross sections we set the upper limits on the observed
cross sections and the branching fractions for decay into these
final states at 90% C.L..Comment: 7 pages, 2 figure
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays
By analyzing about 33 data sample collected at and around 3.773
GeV with the BES-II detector at the BEPC collider, we directly measure the
branching fractions for the neutral and charged inclusive semimuonic decays
to be and , and determine the ratio of the two branching
fractions to be
The pole in
Using a sample of 58 million events recorded in the BESII detector,
the decay is studied. There are conspicuous
and signals. At low mass, a large
broad peak due to the is observed, and its pole position is determined
to be - MeV from the mean of six analyses.
The errors are dominated by the systematic errors.Comment: 15 pages, 6 figures, submitted to PL
A study of charged kappa in
Based on events collected by BESII, the decay
is studied. In the invariant mass
spectrum recoiling against the charged , the charged
particle is found as a low mass enhancement. If a Breit-Wigner function of
constant width is used to parameterize the kappa, its pole locates at MeV/. Also in this channel,
the decay is observed for the first time.
Its branching ratio is .Comment: 14 pages, 4 figure
Measurement of \psip Radiative Decays
Using 14 million psi(2S) events accumulated at the BESII detector, we report
first measurements of branching fractions or upper limits for psi(2S) decays
into gamma ppbar, gamma 2(pi^+pi^-), gamma K_s K^-pi^++c.c., gamma K^+ K^-
pi^+pi^-, gamma K^{*0} K^- pi^+ +c.c., gamma K^{*0}\bar K^{*0}, gamma pi^+pi^-
p pbar, gamma 2(K^+K^-), gamma 3(pi^+pi^-), and gamma 2(pi^+pi^-)K^+K^- with
the invariant mass of hadrons below 2.9GeV/c^2. We also report branching
fractions of psi(2S) decays into 2(pi^+pi^-) pi^0, omega pi^+pi^-, omega
f_2(1270), b_1^\pm pi^\mp, and pi^0 2(pi^+pi^-) K^+K^-.Comment: 5 pages, 4 figure
Measurements of and decays into and
Using 58 million and 14 million events collected by the
BESII detector at the BEPC, branching fractions or upper limits for the decays
and and are measured. For the isospin violating decays, the upper
limits are determined to be and at the 90% confidence level. The isospin
conserving process is observed for the
first time, and its branching fraction is measured to be , where the
first error is statistical and the second one is systematic. No signal is observed in decays, and is set at the 90%
confidence level. Branching fractions of decays into and are also reported, and the sum
of these branching fractions is determined to be .Comment: 7 pages, 10 figures. Phys.Rev.D comments considere
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