Phytochelatins (PCs), a family of heavy metal-inducible peptides important in the detoxification of heavy metals, have been identified in plants and some microorganisms, including Schizosaccharomyces ...pombe, but not in animals. PCs are synthesized enzymatically from glutathione (GSH) by PC synthase in the presence of heavy metal ions. In Arabidopsis, the CAD1 gene, identified by using Cd-sensitive, PC-deficient cad1 mutants, has been proposed to encode PC synthase. Using a positional cloning strategy, we have isolated the CAD1 gene. Database searches identified a homologous gene in S. pombe, and a mutant with a targeted deletion of this gene was also Cd sensitive and PC deficient. Extracts of Escherichia coli cells expressing a CAD1 cDNA or the S. pombe gene catalyzing GSH-dependent, heavy metal-activated synthesis of PCs in vitro demonstrated that both genes encode PC synthase activity. Both enzymes were activated by a range of metal ions. In contrast, reverse transcription-polymerase chain reaction experiments showed that expression of the CAD1 mRNA is not influenced by the presence of Cd. A comparison of the two predicted amino acid sequences revealed a highly conserved N-terminal region, which is presumed to be the catalytic domain, and a variable C-terminal region containing multiple Cys residues, which is proposed to be involved in activation of the enzyme by metal ions. Interestingly, a similar gene was identified in the nematode, Caenorhabditis elegans, suggesting that PCs may also be expressed in some animal species.
We present a measurement of the left-right cross-section asymmetry ( A(LR)) for Z boson production by e(+)e(-) collisions. The measurement includes the final data taken with the SLD detector at the ...SLAC Linear Collider during the period 1996-1998. Using a sample of 383 487 Z decays collected during the 1996-1998 runs we measure the pole value of the asymmetry, A(0)(LR), to be 0.150 56+/-0.002 39 which is equivalent to an effective weak mixing angle of sin (2)straight theta(eff)(W) = 0.231 07+/-0.000 30. Our result for the complete 1992-1998 data set comprising approximately 537 000 Z decays is sin (2)straight theta(eff)(W) = 0.230 97+/-0.000 27.
Oxidation of methanethiol (MT) is a significant step in the sulfur cycle. MT is an intermediate of metabolism of globally significant organosulfur compounds including dimethylsulfoniopropionate ...(DMSP) and dimethylsulfide (DMS), which have key roles in marine carbon and sulfur cycling. In aerobic bacteria, MT is degraded by a MT oxidase (MTO). The enzymatic and genetic basis of MT oxidation have remained poorly characterized. Here, we identify for the first time the MTO enzyme and its encoding gene (mtoX) in the DMS-degrading bacterium Hyphomicrobium sp. VS. We show that MTO is a homotetrameric metalloenzyme that requires Cu for enzyme activity. MTO is predicted to be a soluble periplasmic enzyme and a member of a distinct clade of the Selenium-binding protein (SBP56) family for which no function has been reported. Genes orthologous to mtoX exist in many bacteria able to degrade DMS, other one-carbon compounds or DMSP, notably in the marine model organism Ruegeria pomeroyi DSS-3, a member of the Rhodobacteraceae family that is abundant in marine environments. Marker exchange mutagenesis of mtoX disrupted the ability of R. pomeroyi to metabolize MT confirming its function in this DMSP-degrading bacterium. In R. pomeroyi, transcription of mtoX was enhanced by DMSP, methylmercaptopropionate and MT. Rates of MT degradation increased after pre-incubation of the wild-type strain with MT. The detection of mtoX orthologs in diverse bacteria, environmental samples and its abundance in a range of metagenomic data sets point to this enzyme being widely distributed in the environment and having a key role in global sulfur cycling.
Aim To assess whether there is a significant difference in the incidence of patients with metastases of rectal carcinoma at 1 year follow-up between magnetic resonance imaging (MRI)-detected ...extramural venous invasion (EMVI) and those without. Materials and methods A search of our institution's cancer registry revealed 788 patients with rectal carcinoma between January 2007 and April 2012. Those who were initially staged using MRI and computed tomography (CT) chest/abdomen/pelvis, and followed-up with a CT chest/abdomen/pelvis examination at 1 year were included in this retrospective study. Patients with synchronous metastases were excluded, leaving a cohort of 202 cases. Two consultant radiologists reviewed all MRI images and gave a consensus opinion regarding EMVI grade and vessel size involved. All CT images were reviewed for metastases. Results were analysed using chi-squared and Fisher's exact tests. Results There were 53 cases (26.2%) of EMVI-positive rectal carcinoma. Of the patients with EMVI, 24.5% developed metastases at 1 year follow-up, compared to 6.7% of those without. There is a significant difference in prognosis between those patients with and those without MRI-detected EMVI (χ2 = 12.29, p < 0·001). Those with EMVI have a 3.7 times increased relative risk of developing metachronous metastases within 1 year of diagnosis. Conclusion MRI-detected EMVI-positive rectal carcinomas are associated with an increased risk of metachronous metastases within 1 year of diagnosis. Currently, EMVI status does not directly influence the initial management of rectal carcinoma. This available and potentially prognostic feature could be used to guide treatment pathways to increase disease-free survival.
We have developed a new technique for inclusive reconstruction of the energy of B hadrons. The excellent efficiency and resolution of this technique allow us to make the most precise determination of ...the b -quark fragmentation function, using e{sup +}e{sup -}{yields}Z{sup 0} decays recorded in the SLAC Large Detector experiment. We compared our measurement with the predictions of a number of fragmentation models. We excluded several of these models and measured the average scaled energy of weakly decaying B hadrons to be <x{sub B}>=0.714{+-}0.005(stat ){+-}0.007(syst){+-}0.00 2 (model dependence). (c) 2000 The American Physical Society.
We present final measurements of the Z boson-lepton coupling asymmetry parameters A(e), A(mu), and A(tau) with the complete sample of polarized Z bosons collected by the SLD detector at the SLAC ...Linear Collider. From the left-right production and decay polar angle asymmetries in leptonic Z decays we measure A(e) = 0.1544+/-0.0060, A(mu) = 0.142+/-0.015, and A(tau) = 0.136+/-0.015. Combined with our left-right asymmetry measured from hadronic decays, we find A(e) = 0.1516+/-0.0021. Assuming lepton universality, we obtain a combined effective weak mixing angle of sin (2)theta(eff)(W) = 0.230 98+/-0.000 26.
Chronic exposure to high temperatures may leave freshwater fishes vulnerable to opportunistic pathogens, particularly during early life stages. Lake sturgeon, Acipenser fulvescens, populations within ...the northern expanse of their range in Manitoba, Canada, may be susceptible to high temperature stress and pathogenic infection. We acclimated developing lake sturgeon for 22 days to two ecologically relevant, summer temperatures (16 and 20°C). Individuals from both acclimation treatments were then exposed to 0, 30 and 60 µg ml-1 bacterial lipopolysaccharides (endotoxins), as an immune stimulus, for 48 h and sampled 4 and 48 h during trial exposures and following a 7 day recovery period. We then measured whole-body transcriptional (mRNA) responses involved in the innate immune, stress and fatty acid responses following acute exposure to the bacterial endotoxins. Data revealed that overall levels of mRNA transcript abundance were higher in 20°C-reared sturgeon under control conditions. However, following exposure to a bacterial stimulus, lake sturgeon acclimated to 16°C produced a more robust and persistent transcriptional response with higher mRNA transcript abundance across innate immune, stress and fatty acid responses than their 20°C-acclimated counterparts. Additional whole-animal performance metrics (critical thermal maximum, metabolic rate, cortisol concentration and whole-body and mucosal lysozyme activity) demonstrated acclimation-specific responses, indicating compromised metabolic, stress and enzymatic capacity following the initiation of immune-related responses. Our study showed that acclimation to 20°C during early development impaired the immune capacity of developing lake sturgeon as well as the activation of molecular pathways involved in the immune, stress and fatty acid responses. The present study highlights the effects of ecologically relevant, chronic thermal stress on seasonal pathogen susceptibility in this endangered species.
In comparison to most modern teleost fishes, sturgeons generally display muted stress responses. While a muted stress response appears to be ubiquitous across sturgeon species, the mechanisms ...unpinning this muted response have not been fully described. The objective of this study was to determine the patterns of hematological and transcriptomic change in muscle tissue following an acute high temperature stress (critical thermal maxima; CTmax) in two locally co-occurring but evolutionarily distant sturgeon species (Atlantic and shortnose sturgeon). The most striking pattern found was that Atlantic sturgeon launched a vigorous transcriptomic response at CTmax, whereas shortnose sturgeon did not. In contrast, shortnose sturgeon have significantly higher cortisol than Atlantics at CTmax, reconfirming that shortnose have a less muted cortisol stress response. Atlantic sturgeon downregulated a number of processes, included RNA creation/processing, methylation and immune processes. Furthermore, a number of genes related to heat shock proteins were differentially expressed at CTmax in Atlantic sturgeon but none of these genes were significantly changed in shortnose sturgeon. We also note that the majority of differentially expressed genes of both species are undescribed and have no known orthologues. These results suggest that, while sturgeons as a whole may show muted stress responses, individual sturgeon species likely use different inducible strategies to cope with acute high temperature stress.
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•Atlantic and shortnose sturgeon likely utilize divergent inducible responses to acute thermal stress.•Atlantic sturgeon launch a robust transcriptomic response to acute heat stress yet shortnose sturgeon do not.•Genes related to heat shock protein are differentially expressed at CTmax by Atlantic but not in shortnose sturgeon.•Contrarily, acute heat stress elicits a higher cortisol response in shortnose compared to Atlantic sturgeon.•RNA processing, transcription and methylation was downregulated in Atlantic sturgeon.
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