Fission yeast Swi2 designates cell-type specific donor and stimulates Rad51-driven strand exchange for mating-type switching

A haploid of the fission yeast Schizosaccharomyces pombe expresses either the P or M mating-type, determined by the active, euchromatic, mat1 cassette. Mating-type is switched by Rad51-driven gene conversion of mat1 using a heterochromatic donor cassette, mat2-P or mat3-M. The Swi2-Swi5 complex, a mating-type switching factor, is central to this process by designating a preferred donor in a cell-type-specific manner. Swi2-Swi5 selectively enables one of two cis-acting recombination enhancers, SRE2 adjacent to mat2-P or SRE3 adjacent to mat3-M. Here, we identified two functionally important motifs in Swi2, a Swi6 (HP1 homolog)-binding site and two DNA-binding AT-hooks. Genetic analysis demonstrated that the AT-hooks were required for Swi2 localization at SRE3 to select the mat3-M donor in P cells, while the Swi6-binding site was required for Swi2 localization at SRE2 to select mat2-P in M cells. In addition, the Swi2-Swi5 complex promoted Rad51-driven strand exchange in vitro. Taken together, our results show how the Swi2-Swi5 complex would localize to recombination enhancers through a cell-type specific binding mechanism and stimulate Rad51-driven gene conversion at the localization site.

Euchromatin factors HULC and Set1C affect heterochromatin organization and mating-type switching in fission yeast Schizosaccharomyces pombe

Mating-type (P or M) of fission yeast Schizosaccharomyces pombe is determined by the transcriptionally active mat1 cassette and is switched by gene conversion using a donor, either mat2 or mat3, located in an adjacent heterochromatin region (mating-type switching; MTS). In the switching process, heterochromatic donors of genetic information are selected based on the P or M cell type and on the action of two recombination enhancers, SRE2 promoting the use of mat2-P and SRE3 promoting the use of mat3-M, leading to replacement of the content of the expressed mat1 cassette. Recently, we found that the histone H3K4 methyltransferase complex Set1C participates in donor selection, raising the question of how a complex best known for its effects in euchromatin controls recombination in heterochromatin. Here, we report that the histone H2BK119 ubiquitin ligase complex HULC functions with Set1C in MTS, as mutants in the shf1, brl1, brl2 and rad6 genes showed defects similar to Set1C mutants and belonged to the same epistasis group as set1Δ. Moreover, using H3K4R and H2BK119R histone mutants and a Set1-Y897A catalytic mutant, we found that ubiquitylation of histone H2BK119 by HULC and methylation of histone H3K4 by Set1C are functionally coupled in MTS. Cell-type biases in MTS in these mutants suggested that HULC and Set1C inhibit the use of the SRE3 recombination enhancer in M cells, thus favoring SRE2 and mat2-P. Consistent with this, imbalanced switching in the mutants was traced to compromised association of the directionality factor Swi6 with the recombination enhancers in M cells. Based on their known effects at other chromosomal locations, we speculate that HULC and Set1C control nucleosome mobility and strand invasion near the SRE elements. In addition, we uncovered distinct effects of HULC and Set1C on histone H3K9 methylation and gene silencing, consistent with additional functions in the heterochromatic domain.

Cooperative interactions facilitate stimulation of Rad51 by the Swi5-Sfr1 auxiliary factor complex

Although Rad51 is the key protein in homologous recombination (HR), a major DNA double-strand break repair pathway, several auxiliary factors interact with Rad51 to promote productive HR. We present an interdisciplinary characterization of the interaction between Rad51 and Swi5-Sfr1, a conserved auxiliary factor. Two distinct sites within the intrinsically disordered N-terminus of Sfr1 (Sfr1N) were found to cooperatively bind Rad51. Deletion of this domain impaired Rad51 stimulation in vitro and rendered cells sensitive to DNA damage. By contrast, amino acid-substitution mutants, which had comparable biochemical defects, could promote DNA repair, suggesting that Sfr1N has another role in addition to Rad51 binding. Unexpectedly, the DNA repair observed in these mutants was dependent on Rad55-Rad57, another auxiliary factor complex hitherto thought to function independently of Swi5-Sfr1. When combined with the finding that they form a higher-order complex, our results imply that Swi5-Sfr1 and Rad55-Rad57 can collaboratively stimulate Rad51 in Schizosaccharomyces pombe.

Mating-type switching by homology-directed recombinational repair: a matter of choice

In eukaryotes, all DNA transactions happen in the context of chromatin that often takes part in regulatory mechanisms. In particular, chromatin structure can regulate exchanges of DNA occurring through homologous recombination. Few systems have provided as detailed a view on this phenomenon as mating-type switching in yeast. Mating-type switching entails the choice of a template for the gene conversions of the expressed mating-type locus. In the fission yeast Schizosaccharomyces pombe, correct template choice requires two competing small recombination enhancers, SRE2 and SRE3, that function in the context of heterochromatin. These two enhancers act with the Swi2/Swi5 recombination accessory complex to initiate strand exchange in a cell-type-specific manner, from SRE2 in M cells and SRE3 in P cells. New research indicates that the Set1C complex, responsible for H3K4 methylation, and the Brl2 ubiquitin ligase, that catalyzes H2BK119 ubiquitylation, participate in the cell-type-specific selection of SRE2 or SRE3. Here, we review these findings, compare donor preference in S. pombe to the distantly related budding yeast Saccharomyces cerevisiae, and contrast the positive effects of heterochromatin on the donor selection process with other situations, where heterochromatin represses recombination.

Design protocol of microjet mixers for achieving desirable mixing times with arbitrary flow rate ratios

We extensively examined the performance of microjet mixers.

Development of compartment for studies on the growth of protein crystals in space

To clarify the growth mechanism of a protein crystal, it is essential to measure its growth rate with respect to the supersaturation. We developed a compartment (growth cell) for measuring the growth rate (<0.1 nm s(-1)) of the face of a protein crystal at a controlled supersaturation by interferometry over a period of half a year in space. The growth cell mainly consists of quartz glass, in which the growth solution and a seed crystal are enclosed by capillaries, the screw sample holder, and a helical insert. To avoid the destruction of the cell and the evaporation of the water from the solution inside the cell, we selected the materials for these components with care. The equipment was successfully used to examine the growth of a lysozyme crystal at a controlled supersaturation in space, where convection is negligible because of the microgravity environment, thereby advancing our understanding of the mechanism of protein crystal growth from solution. The technique used to develop the growth cell is useful not only for space experiments but also for kinetic studies of materials with very slow growth and dissolution rates (<10(-3) nm s(-1)).

Top-down assessment of the Asian carbon budget since the mid 1990s

Increasing atmospheric carbon dioxide (CO₂) is the principal driver of anthropogenic climate change. Asia is an important region for the global carbon budget, with 4 of the world's 10 largest national emitters of CO₂. Using an ensemble of seven atmospheric inverse systems, we estimated land biosphere fluxes (natural, land-use change and fires) based on atmospheric observations of CO₂ concentration. The Asian land biosphere was a net sink of −0.46 (−0.70–0.24) PgC per year (median and range) for 1996–2012 and was mostly located in East Asia, while in South and Southeast Asia the land biosphere was close to carbon neutral. In East Asia, the annual CO₂ sink increased between 1996–2001 and 2008–2012 by 0.56 (0.30–0.81) PgC, accounting for ∼35% of the increase in the global land biosphere sink. Uncertainty in the fossil fuel emissions contributes significantly (32%) to the uncertainty in land biosphere sink change.

Land biosphere uptake of carbon is important in mitigating the anthropogenic increase in atmospheric CO₂ and its climate forcing. Here, the authors show that land biosphere uptake of carbon in Asia has increased substantially since the mid 1990s, likely owing to reforestation and regional climate change.

CLASP2 Has Two Distinct TOG Domains That Contribute Differently to Microtubule Dynamics

CLIP-associated proteins CLASPs are mammalian microtubule (MT) plus-end tracking proteins (+TIPs) that promote MT rescue in vivo. Their plus-end localization is dependent on other +TIPs, EB1 and CLIP-170, but in the leading edge of the cell, CLASPs display lattice-binding activity. MT association of CLASPs is suggested to be regulated by multiple TOG (tumor overexpressed gene) domains and by the serine-arginine (SR)-rich region, which contains binding sites for EB1. Here, we report the crystal structures of the two TOG domains of CLASP2. Both domains consist of six HEAT repeats, which are similar to the canonical paddle-like tubulin-binding TOG domains, but have arched conformations. The degrees and directions of curvature are different between the two TOG domains, implying that they have distinct roles in MT binding. Using biochemical, molecular modeling and cell biological analyses, we have investigated the interactions between the TOG domains and αβ-tubulin and found that each domain associates differently with αβ-tubulin. Our findings suggest that, by varying the degrees of domain curvature, the TOG domains may distinguish the structural conformation of the tubulin dimer, discriminate between different states of MT dynamic instability and thereby function differentially as stabilizers of MTs.

CLASPs are required for proper microtubule localization of end-binding proteins

Microtubule (MT) plus-end tracking proteins (+TIPs) preferentially localize to MT plus ends. End-binding proteins (EBs) are master regulators of the +TIP complex; however, it is unknown whether EBs are regulated by other +TIPs. Here, we show that cytoplasmic linker-associated proteins (CLASPs) modulate EB localization at MTs. In CLASP-depleted cells, EBs localized along the MT lattice in addition to plus ends. The MT-binding region of CLASP was sufficient for restoring normal EB localization, whereas neither EB-CLASP interactions nor EB tail-binding proteins are involved. In vitro assays revealed that CLASP directly functions to remove EB from MTs. Importantly, this effect occurs specifically during MT polymerization, but not at preformed MTs. Increased GTP-tubulin content within MTs in CLASP-depleted cells suggests that CLASPs facilitate GTP hydrolysis to reduce EB lattice binding. Together, these findings suggest that CLASPs influence the MT lattice itself to regulate EB and determine exclusive plus-end localization of EBs in cells.

A marine phytoplankton (Prymnesium parvum) up-regulates ABC transporters and several other proteins to acclimatize with Fe-limitation

Iron (Fe) is one of the vital limiting factors for phytoplankton in vast regions of the contemporary oceans, notably the high nutrient low chlorophyll regions. Therefore, it is apparent to be acquainted with the Fe uptake strategy of marine phytoplankton under Fe-limited condition. In the present study, marine phytoplankton Prymnesium parvum was grown under Fe-deplete (0.0025 μM) and Fe-rich (0.05 μM) conditions, and proteomic responses of the organism to Fe conditions were compared. In sodium dodecyl sulfate (SDS) gel electrophoresis, 7 proteins (16, 18, 32, 34, 75, 82, and 116 kDa) were highly expressed under Fe-deplete condition, while one protein (23 kDa) was highly expressed under Fe-rich condition. These proteins were subjected to 2-dimensional gel electrophoresis (2-D DIGE) to differentiate individual proteins, and were identified by matrix-assisted laser desorption-ionization-time of flight-mass spectrometer (MALDI-TOF-MS) analysis. The results showed that under Fe-deplete condition P. parvum increases the biosynthesis of ATP binding cassette (ABC) transporters, flagellar associated protein (FAP), and Phosphoribosylaminoimidazole-succinocarboxamide synthase. These proteins are assumed to be involved in a number of cellular biochemical processes that facilitate Fe acquisition in phytoplankton. Under Fe-deplete condition, P. parvum increases the synthesis of ribulose biphosphate carboxylase (RuBisCo), malate dehydrogenase, and two Fe-independent oxidative stress response proteins, manganese superoxide dismutase (MnSOD) and Serine threonine kinase (STK). Thus, marine phytoplankton may change their Fe acquisition strategy by altering the biosynthesis of several proteins in order to cope with Fe-limitation.

A novel PAR-1-binding protein, MTCL1, plays critical roles in organizing microtubules in polarizing epithelial cells

The establishment of epithelial polarity is tightly linked to the dramatic reorganization of microtubules (MTs) from a radial array to a vertical alignment of non-centrosomal MT bundles along the lateral membrane and a meshwork under the apical and basal membranes. However, little is known about the underlying molecular mechanism of this polarity-dependent MT remodeling. The evolutionarily conserved cell polarity-regulating kinase PAR-1, whose activity is essential for maintaining the dynamic state of MTs, plays indispensable roles to promote this process. Here, we identify a novel PAR-1-binding protein, named MTCL1 (Microtubule crosslinking factor 1), which crosslinks MTs through its N-terminal MT-binding region and subsequent coiled-coil motifs. MTCL1 colocalized with the apicobasal MT bundles in epithelial cells, and its knockdown impaired the development of these MT bundles and the epithelial cell specific columnar shape. Rescue experiments revealed that the N-terminal MT-binding region was indispensable for restoring these defects of the knockdown cells. MT regrowth assays indicated that MTCL1 was not required for the initial radial growth of MTs from the apical centrosome, but was essential for the accumulation of non-centrosomal MTs to the sublateral regions. Interestingly, MTCL1 recruited a subpopulation of PAR-1b to the apicobasal MT bundles, and its interaction with PAR-1b was required for MTCL1-dependent development of the apicobasal MT bundles. These results suggest that MTCL1 mediates the epithelial cell-specific reorganization of non-centrosomal MTs through its MT-crosslinking activity, and cooperates with PAR-1b to maintain the correct temporal balance between dynamic and stable MTs within the apicobasal MT bundles.

Crystallization and preliminary X-ray data analysis of the pXO1 plasmid-partitioning factor TubZ from Bacillus cereus

TubZ is a structural homologue of tubulin and FtsZ GTPases, which are involved in the type III plasmid-partitioning system. TubZ assembles into polymers in a GTP-dependent manner and drives plasmid segregation as `cytomotive' filaments. In this study, C-terminally truncated TubZ from Bacillus cereus was crystallized in the presence or absence of GDP by the hanging-drop vapour-diffusion method. The crystal of TubZ in complex with GDP belonged to the monoclinic space group P2(1), with unit-cell parameters a=67.05, b=84.49, c=67.66 Å, β=92.92°, and was non-isomorphous with GDP-bound TubZ previously crystallized in the presence of the slowly hydrolysable GTP analogue GTPγS. TubZ was also crystallized in the free form and the crystal belonged to space group P2(1), with unit-cell parameters a=53.91, b=65.54, c=58.18 Å, β=106.19°. Data were collected to 1.7 and 2.1 Å resolution for the free and GDP-bound forms, respectively.

Phytotoxicity of arsenate and salinity on early seedling growth of rice (Oryza sativa L.): a threat to sustainable rice cultivation in South and South-East Asia

Arsenic (As) contamination is an important environmental consequence in some parts of salinity-affected South (S) and South-East (SE) Asia. In this study, we investigated the individual and combined phytotoxicity of arsenic (As) [arsenate; As(V)] and salinity (NaCl) on early seedling growth (ESG) of saline-tolerant and non-tolerant rice varieties. Germination percentage (GP), germination speed (GS) and vigor index (VI) of both saline-tolerant and non-tolerant rice varieties decreased significantly (p > 0.01) with increasing As(V) and NaCl concentrations. The highest GP (91%) was observed for saline non-tolerant BRRI dhan28 and BRRI dhan49, while the lowest (62%) was for saline-tolerant BRRI dhan47. The ESG parameters, such as weights and relative lengths of plumule and radicle, also decreased significantly (p < 0.01) with increasing As(V) and NaCl concentrations. Relative radicle length was more affected than plumule length by As(V) and NaCl. Although VI of saline-tolerant and non-tolerant rice seedlings showed significant variation (p < 0.05), weights and lengths of plumule and radicle of different rice varieties did not show significant variation for As(V) and NaCl treatments. Results reveal that the combined phytotoxicity of As(V) and NaCl on rice seed germination and ESG are greater than their individual toxicities, and some saline-tolerant rice varieties are more resistant to the combined phytotoxicity of As(V) and NaCl than the saline non-tolerant varieties.

Effect of external iron and arsenic species on chelant-enhanced iron bioavailability and arsenic uptake in rice (Oryza sativa L.)

This study was conducted to investigate the effect of external iron status and arsenic species on chelant-enhanced iron bioavailability and arsenic uptake. Rice seedlings (Oryza sativa L.) were used as model plant, and were grown in artificially contaminated sandy soils irrigated with Murashige and Skoog (MS) culture solution. Arsenate uptake in roots and shoots of rice seedlings were affected significantly (p>0.05) while dimethylarsinic acid (DMAA) was not by the additional iron and chelating ligand treatments. Regardless of iron concentrations in the soil solution, HIDS increased arsenic uptake for roots more than EDTA and EDDS. Chelating ligands and arsenic species also influenced iron uptake in rice roots. Irrespective of arsenic species, HIDS was found to be more effective in the increase of iron bioavailability and uptake in rice roots compared to other chelants. There was a significant positive correlation (r=0.78, p<0.05) between arsenate and iron concentrations in the roots of rice seedlings grown with or without additional iron indicating that arsenate inhibit iron uptake. In contrast, there was no correlation between iron and DMAA uptake in roots. Poor correlation between iron and arsenic in shoots indicated that iron uptake in shoots was neither affected by additional iron nor by arsenic species. Compared to the control, chelating ligands increased iron uptake in shoots of rice seedlings significantly (p<0.05). Regardless of additional iron and arsenic species, iron uptake in rice shoots did not differed among EDTA, EDDS, and HIDS treatments.

Effects of karaya saponin and Rhodobacter capsulatus on yolk cholesterol in laying hens

1. It has been reported that karaya saponin and Rhodobacter capsulatus individually have hypocholesterolaemic activity in laying hens. This study focuses on the effect of adding karaya saponin with R. capsulatus to hen's diet with regard to serum and egg yolk cholesterol and triglycerides. 2. A total of 56 Boris Brown laying hens were divided into 7 groups at 20 weeks of age. Combinations of 25, 50, 75 mg kg(-1) karaya saponin and R. capsulatus 200 and 400 mg kg(-1) were used as treatment groups. 3. After 8 weeks of supplementation, the effects of all the combinations of karaya saponin and R. capsulatus on serum and egg yolk cholesterol, triglycerides, and high-density lipoprotein (HDL)-cholesterol were greater than either karaya saponin or R. capsulatus alone. The combination of karaya saponin 50 mg kg(-1)+ R. capsulatus 400 mg kg(-1) exhibited the greatest reduction of serum (325%) and yolk (225%) cholesterol and the greatest increase of faecal, liver bile acids and yolk fatty acid (oleic, linoleic and linolenic) concentrations. In addition, egg production and yolk colour were significantly improved by the combined use of karaya saponin and R. capsulatus supplementation. 4. Therefore, the dietary supplementation of karaya saponin and R. capsulatus may lead to the production of a low-cholesterol egg, with production performance maintained at a standard level.

Intraoperative administration of inhaled carbon monoxide reduces delayed graft function in kidney allografts in Swine

Ischemia/reperfusion injury and delayed graft function (DGF) following organ transplantation adversely affect graft function and survival. A large animal model has not been characterized. We developed a pig kidney allograft model of DGF and evaluated the cytoprotective effects of inhaled carbon monoxide (CO). We demonstrate that donor warm ischemia time is a critical determinant of DGF as evidenced by a transient (4-6 days) increase in serum creatinine and blood urea nitrogen following transplantation before returning to baseline. CO administered to recipients intraoperatively for 1 h restored kidney function more rapidly versus air-treated controls. CO reduced acute tubular necrosis, apoptosis, tissue factor expression and P-selectin expression and enhanced proliferative repair as measured by phosphorylation of retinol binding protein and histone H3. Gene microarray analyses with confirmatory PCR of biopsy specimens showed that CO blocked proinflammatory gene expression of MCP-1 and heat shock proteins. In vitro in pig renal epithelial cells, CO blocks anoxia-reoxygenation-induced cell death while promoting proliferation. This large animal model of DGF can be utilized for testing therapeutic strategies to reduce or prevent DGF in humans. The efficacy of CO on improving graft function posttransplant validates the model and offers a potentially important therapeutic strategy to improve transplant outcomes.

Search for pair production of supersymmetric top quarks in dilepton events from pp collisions at sqrt[s]=1.96 TeV

We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark t{1}) decaying to a b quark and a chargino χ{1}{±} with a subsequent χ{1}{±} decay into a neutralino χ{1}{0}, lepton ℓ, and neutrino ν. Using a data sample corresponding to 2.7  fb{-1} of integrated luminosity of pp collisions at sqrt[s]=1.96  TeV collected by the CDF II detector, we reconstruct the mass of top squark candidate events and fit the observed mass spectrum to a combination of standard model processes and t{1}t{1} signal. We find no evidence for t{1}t{1} production and set 95% C.L. limits on the masses of the top squark and the neutralino for several values of the chargino mass and the branching ratio B(χ{1}{±}→χ{1}{0}ℓ{±}ν).

First measurement of the b-jet cross section in events with a W boson in pp collisions at square root(s) = 1.96 TeV

The cross section for jets from b quarks produced with a W boson has been measured in pp collision data from 1.9 fb(-1) of integrated luminosity recorded by the CDF II detector at the Tevatron. The W+b-jets process poses a significant background in measurements of top quark production and prominent searches for the Higgs boson. We measure a b-jet cross section of 2.74+/-0.27(stat)+/-0.42(syst) pb in association with a single flavor of leptonic W boson decay over a limited kinematic phase space. This measured result cannot be accommodated in several available theoretical predictions.

Seasonal changes of arsenic speciation in lake waters in relation to eutrophication

In this study, the influence of eutrophication on arsenic speciation in lake waters was investigated. Surface water samples (n=1-10) were collected from 18 lakes in Japan during July 2007 and February 2008. The lakes were classified into mesotrophic (7 lakes) and eutrophic (11 lakes) based on the total phosphate (T-P) and chlorophyll-a (Chl-a) concentrations in water column. Inorganic, methylated and ultraviolet-labile fractions of arsenic species were determined by combining hydride generation atomic absorption spectrometry with ultraviolet irradiation. Organoarsenicals (mainly methylated and ultraviolet-labile fractions) comprised 30-60% of the total arsenic in most lakes during summer. On the other hand, inorganic arsenic species (As(III+V)) dominates (about 60-85%) during winter. The occurrence of ultraviolet-labile fractions of arsenic was higher in eutrophic lakes than those in mesotrophic lakes in both seasons. The concentration of dimethyl arsenic (DMAA) was high in eutrophic lakes during winter; and in mesotrophic lakes during summer. The results suggest that the conversion of As(III+V) to more complicated organoarsenicals occurred frequently in eutrophic lakes compared to that in mesotrophic lakes, which is thought to be the influence of biological activity in the water column. The distribution of arsenic species were well correlated with phosphate concentrations than those of Chl-a. This might be due to the competitive uptake of As(V) and phosphate by phytoplankton. The organoarsenicals (OrgAs)/As(V) ratio was higher at low phosphate concentration indicating that conversion of As(V) to OrgAs species was more active in phosphate-exhausted lakes with high phytoplankton density.

Search for the associated production of the standard-model Higgs Boson in the all-hadronic channel

We report on a search for the standard-model Higgs boson in pp collisions at square root(s) = 1.96 TeV using an integrated luminosity of 2.0 fb(-1). We look for production of the Higgs boson decaying to a pair of bottom quarks in association with a vector boson V (W or Z) decaying to quarks, resulting in a four-jet final state. Two of the jets are required to have secondary vertices consistent with B-hadron decays. We set the first 95% confidence level upper limit on the VH production cross section with V(--> qq/qq')H(--> bb) decay for Higgs boson masses of 100-150 GeV/c2 using data from run II at the Fermilab Tevatron. For m(H) = 120 GeV/c2, we exclude cross sections larger than 38 times the standard-model prediction.

Search for Higgs bosons predicted in two-Higgs-doublet models via decays to tau lepton pairs in 1.96 TeV pp collisions

We present the results of a search for Higgs bosons predicted in two-Higgs-doublet models, in the case where the Higgs bosons decay to tau lepton pairs, using 1.8 fb(-1) of integrated luminosity of pp collisions recorded by the CDF II experiment at the Fermilab Tevatron. Studying the mass distribution in events where one or both tau leptons decay leptonically, no evidence for a Higgs boson signal is observed. The result is used to infer exclusion limits in the two-dimensional space of tanbeta versus m(A) (the ratio of the vacuum expectation values of the two Higgs doublets and the mass of the pseudoscalar boson, respectively).

First observation of B(s)(0) --> D(s)(+/-)K(-/+) and measurement of the ratio of branching fractions B(B(s)(0) --> D(s)(+/-)K(-/+)/B(B(s)(0) --> D(s)(+)pi(-))

A combined mass and particle identification fit is used to make the first observation of the decay B(s)(0) --> D(s)(+/-)K(-/+) and measure the branching fraction of B(s)(0) --> D(s)(+/-)K(-/+) relative to B(s)(0) --> D(s)(+)pi(-). This analysis uses 1.2 fb(-1) integrated luminosity of pp collisions at square root(s) = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron collider. We observe a B(s)(0) --> D(s)(+/-)K(-/+) signal with a statistical significance of 8.1 sigma and measure B(B(s)(0) --> D(s)(+/-)K(-/+) /B(B(s)(0) --> D(s)(+)pi(-) 0.097+/-0.018(stat) +/- 0.009(syst).

Precision measurement of the X(3872) mass in J/psi pi(+) pi(-) decays

We present an analysis of the mass of the X(3872) reconstructed via its decay to J/psi pi(+)pi(-) using 2.4 fb(-1) of integrated luminosity from pp collisions at square root(s)=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. The possible existence of two nearby mass states is investigated. Within the limits of our experimental resolution the data are consistent with a single state, and having no evidence for two states we set upper limits on the mass difference between two hypothetical states for different assumed ratios of contributions to the observed peak. For equal contributions, the 95% confidence level upper limit on the mass difference is 3.6 MeV/c(2). Under the single-state model the X(3872) mass is measured to be 3871.61+/-0.16(stat)+/-0.19(syst) MeV/c(2), which is the most precise determination to date.

Search for a standard model Higgs boson in WH --> lvbb in pp collisions at square root s = 1.96 TeV

We present a search for a standard model Higgs boson produced in association with a W boson using 2.7 fb(-1) of integrated luminosity of pp collision data taken at square root s = 1.96 TeV. Limits on the Higgs boson production rate are obtained for masses between 100 and 150 GeV/c(2). Through the use of multivariate techniques, the analysis achieves an observed (expected) 95% confidence level upper limit of 5.6 (4.8) times the theoretically expected production cross section for a standard model Higgs boson with a mass of 115 GeV/c(2).

Search for charged Higgs bosons in decays of top quarks in pp collisions at square root s = 1.96 TeV

We report on the first direct search for charged Higgs bosons decaying into cs in tt events produced by pp collisions at square root s = 1.96 TeV. The search uses a data sample corresponding to an integrated luminosity of 2.2 fb(-1) collected by the CDF II detector at Fermilab and looks for a resonance in the invariant mass distribution of two jets in the lepton + jets sample of tt candidates. We observe no evidence of charged Higgs bosons in top quark decays. Hence, 95% upper limits on the top quark decay branching ratio are placed at B(t --> H(+)b)< 0.1 to 0.3 for charged Higgs boson masses of 60 to 150 GeV/c(2) assuming B(H(+) --> cs)=1.0. The upper limits on B(t --> H(+)b) are also used as model-independent limits on the decay branching ratio of top quarks to generic scalar charged bosons beyond the standard model.

Hydroxyiminodisuccinic acid (HIDS): A novel biodegradable chelating ligand for the increase of iron bioavailability and arsenic phytoextraction

The influence of biodegradable chelating ligands on arsenic and iron uptake by hydroponically grown rice seedlings (Oryza sativa L.) was investigated. Even though the growth solution contained sufficient Fe, the growth of rice seedlings gradually decreased up to 76% with the increase of pH of the solution from 7 to 11. Iron forms insoluble ferric hydroxide complexes at neutral or alkaline pH in oxic condition. Chelating ligands produce soluble 'Fe-ligand complex' which assist Fe uptake in plants. The biodegradable chelating ligand hydroxyiminodisuccinic acid (HIDS) was more efficient then those of ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), and iminodisuccinic acid (IDS) in the increase of Fe uptake and growth of rice seedling. A total of 79+/-20, 87+/-6, 116+/-15, and 63+/-18mg dry biomass of rice seedlings were produced with the addition of 0.5mM of EDDS, EDTA, HIDS, and IDS in the nutrient solution, respectively. The Fe concentrations in rice tissues were 117+/-15, 82+/-8, 167+/-25, and 118+/-22micromolg(-1) dry weights when 0.25mM of EDDS, EDTA, HIDS, and IDS were added to the nutrient solution, respectively. Most of the Fe accumulated in rice tissues was stored in roots after the addition of chelating ligands in the solution. The results indicate that the HIDS would be a potential alternative to environmentally persistent EDTA for the increase of Fe uptake and plant growth. The HIDS also increased As uptake in rice root though its translocation from root to shoot was not augmented. This study reports HIDS for the first time as a promising chelating ligand for the enhancement of Fe bioavailability and As phytoextraction.

Observation of electroweak single top-quark production

We report the observation of single top-quark production using 3.2 fb(-1) of pp[over ] collision data with sqrt[s]=1.96 TeV collected by the Collider Detector at Fermilab. The significance of the observed data is 5.0 standard deviations, and the expected sensitivity for standard model production and decay is in excess of 5.9 standard deviations. Assuming m(t) = 175 GeV/c(2), we measure a cross section of 2.3(-0.5);(+0.6)(stat + syst) pb, extract the CKM matrix-element value |V(tb)| = 0.91 + or - 0.11(stat + syst) + or - 0.07(theory), and set the limit |V(tb)| > 0.71 at the 95% C.L.

First observation of vector boson pairs in a hadronic final state at the tevatron collider

We present the first observation in hadronic collisions of the electroweak production of vector boson pairs (VV, V = W, Z) where one boson decays to a dijet final state. The data correspond to 3.5 fb(-1) of integrated luminosity of pp[over ] collisions at sqrt[s] = 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron. We observe 1516 + or - 239(stat) + or - 144(syst) diboson candidate events and measure a cross section sigma(pp[over ]-->VV + X) of 18.0 + or - 2.8(stat) + or - 2.4(syst) + or -1.1(lumi) pb, in agreement with the expectations of the standard model.

Search for a fermiophobic Higgs boson decaying into diphotons in pp[over] collisions at sqrt[s] = 1.96 TeV

A search for a narrow diphoton mass resonance is presented based on data from 3.0 fb;{-1} of integrated luminosity from pp[over ] collisions at sqrt[s] = 1.96 TeV collected by the CDF experiment. No evidence of a resonance in the diphoton mass spectrum is observed, and upper limits are set on the cross section times branching fraction of the resonant state as a function of Higgs boson mass. The resulting limits exclude Higgs bosons with masses below 106 GeV/c;{2} at a 95% Bayesian credibility level for one fermiophobic benchmark model.

Search for the production of narrow tb[over] resonances in 1.9 fb;{-1} of pp[over] collisions at sqrt[s] = 1.96 TeV

We present new limits on resonant tb[over] production in pp[over] collisions at sqrt[s] = 1.96 TeV, using 1.9 fb;{-1} of data recorded with the CDF II detector at the Fermilab Tevatron. We reconstruct a candidate tb[over] mass in events with a lepton, neutrino candidate, and two or three jets, and search for anomalous tb[over] production as modeled by W;{'} --> tb[over]. We set a new limit on a right-handed W;{'} with standard model-like coupling, excluding any mass below 800 GeV/c;{2} at 95% C.L. The cross section for any narrow, resonant tb[over] production between 750 and 950 GeV/c;{2} is found to be less than 0.28 pb at 95% C.L. We also present an exclusion of the W;{'} coupling strength versus W;{'} mass over the range 300-950 GeV/c;{2}.