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131.
Khannapho C Zhao H Bonde BK Kierzek AM Avignone-Rossa CA Bushell ME 《Metabolic engineering》2008,10(5):227-233
Using flux variability analysis of a genome scale metabolic network of Streptomyces coelicolor, a series of reactions were identified, from disparate pathways that could be combined into an actinorhodin-generating mini-network. Candidate process feed nutrients that might be expected to influence this network were used in process simulations and in silico predictions compared to experimental findings. Ranking potential process feeds by flux balance analysis optimisation, using either growth or antibiotic production as objective function, did not correlate with experimental actinorhodin yields in fed processes. However, the effect of the feeds on glucose assimilation rate (using glucose uptake as objective function) ranked them in the same order as in vivo antibiotic production efficiency, consistent with results of a robustness analysis of the effect of glucose assimilation on actinorhodin production. 相似文献
132.
LISA WINGATE ULLI SEIBT† KADMIEL MASEYK‡ JÉRÔME OGÉE§ PEDRO ALMEIDA¶ DAN YAKIR‡ JOAO S. PEREIRA¶ MAURIZIO MENCUCCINI 《Global Change Biology》2008,14(9):2178-2193
The oxygen stable isotope composition (δ18O) of CO2 is a valuable tool for studying the gas exchange between terrestrial ecosystems and the atmosphere. In the soil, it records the isotopic signal of water pools subjected to precipitation and evaporation events. The δ18O of the surface soil net CO2 flux is dominated by the physical processes of diffusion of CO2 into and out of the soil and the chemical reactions during CO2–H2O equilibration. Catalytic reactions by the enzyme carbonic anhydrase, reducing CO2 hydration times, have been proposed recently to explain field observations of the δ18O signatures of net soil CO2 fluxes. How important these catalytic reactions are for accurately predicting large‐scale biosphere fluxes and partitioning net ecosystem fluxes is currently uncertain because of the lack of field data. In this study, we determined the δ18O signatures of net soil CO2 fluxes from soil chamber measurements in a Mediterranean forest. Over the 3 days of measurements, the observed δ18O signatures of net soil CO2 fluxes became progressively enriched with a well‐characterized diurnal cycle. Model simulations indicated that the δ18O signatures recorded the interplay of two effects: (1) progressive enrichment of water in the upper soil by evaporation, and (2) catalytic acceleration of the isotopic exchange between CO2 and soil water, amplifying the contributions of ‘atmospheric invasion’ to net signatures. We conclude that there is a need for better understanding of the role of enzymatic reactions, and hence soil biology, in determining the contributions of soil fluxes to oxygen isotope signals in atmospheric CO2. 相似文献
133.
Margot ME Gosman Dirkje S Postma Judith M Vonk Bea Rutgers Monique Lodewijk Mieke Smith Marjan A Luinge Nick HT ten Hacken Wim Timens 《Respiratory research》2008,9(1):1-9
Background
Surfactant protein D (SP-D), an innate immune molecule, plays an important protective role during airway inflammation. Deficiency of this molecule induces emphysematous changes in murine lungs, but its significance in human COPD remains unclear.Methods
We collected bronchoalveolar lavage fluid from 20 subjects with varying degrees of COPD (8 former smokers and 12 current smokers) and 15 asymptomatic healthy control subjects (5 never smokers, 3 remote former smokers, and 7 current smokers). All subjects underwent a complete medical history and pulmonary function testing. SP-D was measured by Enzyme-Linked ImmunoSorbent Assay. Statistical analysis was performed using nonparametric methods and multivariable linear regression for control of confounding. The effect of corticosteroid treatment on SP-D synthesis was studied in vitro using an established model of isolated type II alveolar epithelial cell culture.Results
Among former smokers, those with COPD had significantly lower SP-D levels than healthy subjects (median 502 and 1067 ng/mL, respectively, p = 0.01). In a multivariable linear regression model controlling for age, sex, race, and pack-years of tobacco, COPD was independently associated with lower SP-D levels (model coefficient -539, p = 0.04) and inhaled corticosteroid use was independently associated with higher SP-D levels (398, p = 0.046). To support the hypothesis that corticosteroids increase SP-D production we used type II alveolar epithelial cells isolated from adult rat lungs. These cells responded to dexamethasone treatment by a significant increase of SP-D mRNA (p = 0.041) and protein (p = 0.037) production after 4 days of culture.Conclusion
Among former smokers, COPD is associated with lower levels of SP-D and inhaled corticosteroid use is associated with higher levels of SP-D in the lung. Dexamethasone induced SP-D mRNA and protein expression in isolated epithelial cells in vitro. Given the importance of this molecule as a modulator of innate immunity and inflammation in the lung, low levels may play a role in the pathogenesis and/or progression of COPD. Further, we speculate that inhaled steroids may induce SP-D expression and that this mechanism may contribute to their beneficial effects in COPD. Larger, prospective studies are warranted to further elucidate the role of surfactant protein D in modulating pulmonary inflammation and COPD pathogenesis. 相似文献134.
Spriggs KA Stoneley M Bushell M Willis AE 《Biology of the cell / under the auspices of the European Cell Biology Organization》2008,100(1):27-38
There is now an overwhelming body of evidence to suggest that internal ribosome entry is required to maintain the expression of specific proteins during patho-physiological situations when cap-dependent translation is compromised, for example, following heat shock or during mitosis, hypoxia, differentiation and apoptosis. Translational profiling has been used by several groups to assess the extent to which alternative mechanisms of translation initiation selectively recruit mRNAs to polysomes during cell stress. The data from these studies have shown that under each condition 3-5% of coding mRNAs remain associated with the polysomes. Importantly, the genes identified in each of these studies do not show a significant amount of overlap, suggesting that 10-15% of all mRNAs have the capability for their initiation to occur via alternative mechanism(s). 相似文献
135.
1998年5月-2000年10月间调查了梅州柚果贮藏期的真菌病害,它们是:①柚果绿霉病(Penicilliumdigitatum),②柚果炭疽病(Collettrichumgloeosporioides),③柚果黑腐病(Alternariacitri),④柚果焦腐病(Diplodianatalensis)和⑤柚果酸腐病(Oosporacitri-aurantii)等5种.从几种安全性高的保鲜剂中筛选出1个混用配方,该配方对柚果贮藏防腐保鲜效果明显,贮藏5个月无病斑果达100%,6个月也只有20%的柚果出现少量病斑,且柚果几项质量指标较好. 相似文献
136.
137.
The rate of protein synthesis is rapidly down-regulated in mammalian cells following the induction of apoptosis. Inhibition occurs at the level of polypeptide chain initiation and is accompanied by the phosphorylation of the alpha subunit of initiation factor eIF2 and the caspase-dependent cleavage of initiation factors eIF4G, eIF4B, eIF2alpha and the p35 subunit of eIF3. Proteolytic cleavage of these proteins yields characteristic products which may exert regulatory effects on the translational machinery. Inhibition of caspase activity protects protein synthesis from long-term inhibition in cells treated with some, but not all, inducers of apoptosis. This review describes the initiation factor modifications and the possible signalling pathways by which translation may be regulated during apoptosis. We discuss the significance of the initiation factor cleavages and other changes for protein synthesis, and the implications of these events for our understanding of the cellular changes associated with apoptosis. 相似文献
138.
139.
RAFAEL G. SEVILLA AMALIA DIEZ MICHAEL NORN OLIVIER MOUCHEL MARC JR
ME VRONIQUE VERREZ‐BAGNIS HILDE VAN PELT LAURENCE FAVRE‐KREY GRIGORIOS KREY THE FISHTRACE CONSORTIUM JOS M. BAUTISTA 《Molecular ecology resources》2007,7(5):730-734
This report describes a set of 21 polymerase chain reaction primers and amplification conditions developed to barcode practically any teleost fish species according to their mitochondrial cytochrome b and nuclear rhodopsin gene sequences. The method was successfully tested in more than 200 marine fish species comprising the main Actinopterygii family groups. When used in phylogenetic analyses, its combination of two genes with different evolutionary rates serves to identify fish at the species level. We provide a flow diagram indicating our validated polymerase chain reaction amplification conditions for barcoding and species identification applications as well as population structure or haplotyping analyses, adaptable to high‐throughput analyses. 相似文献
140.
George Skalka Holly Hall Joanna Somers Martin Bushell Anne Willis 《Cell cycle (Georgetown, Tex.)》2019,18(9):963-975
Common hallmarks of cancer include the dysregulation of cell cycle progression and the acquisition of genome instability. In tumors, G1 cell cycle checkpoint induction is often lost. This increases the reliance on a functional G2/M checkpoint to prevent progression through mitosis with damaged DNA, avoiding the introduction of potentially aberrant genetic alterations. Treatment of tumors with ionizing radiation (IR) utilizes this dependence on the G2/M checkpoint. Therefore, identification of factors which regulate this process could yield important biomarkers for refining this widely used cancer therapy. Leucine zipper and ICAT domain containing (LZIC) downregulation has been associated with the development of IR-induced tumors. However, despite LZIC being highly conserved, it has no known molecular function. We demonstrate that LZIC knockout (KO) cell lines show a dysregulated G2/M cell cycle checkpoint following IR treatment. In addition, we show that LZIC deficient cells competently activate the G1 and early G2/M checkpoint but fail to maintain the late G2/M checkpoint after IR exposure. Specifically, this defect was found to occur downstream of PIKK signaling. The LZIC KO cells demonstrated severe aneuploidy indicative of genomic instability. In addition, analysis of data from cancer patient databases uncovered a strong correlation between LZIC expression and poor prognosis in several cancers. Our findings suggest that LZIC is functionally involved in cellular response to IR, and its expression level could serve as a biomarker for patient stratification in clinical cancer practice. 相似文献