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1.
A duplex Escherichia coli bacteriophage M13 genome was constructed containing a single cis-[Pt(NH3)2(d(GpG]] intrastrand cross-link, the major DNA adduct of the anticancer drug cis-diamminedichloroplatinum(II). The duplex dodecamer d(AGAAGGCCTAGA).d(TCTAGGCCTTCT) was ligated into the HincII site of M13mp18 to produce an insertion mutant containing a unique StuI restriction enzyme cleavage site. A genome with a 12-base gap in the minus strand was created by hybridizing HincII-linearized M13mp18 duplex DNA with the single-stranded circular DNA of the 12-base insertion mutant. The dodecamer d(TCTAGGCCTTCT) was synthesized by the solid-phase phosphotriester method and platinated by reaction with cis-[Pt(NH3)2(H2O)2]2+ (yield 39%). Characterization by pH-dependent 1H NMR spectroscopy established that platinum binds to the N7 positions of the adjacent guanosines. The platinated oligonucleotide was phosphorylated in the presence of [gamma-32P]ATP with bacteriophage T4 polynucleotide kinase and incorporated into the 12-base gap of the heteroduplex, thus situating the adduct specifically within the StuI site in the minus strand of the genome. Approximately 80% of the gapped duplexes incorporated a dodecanucleotide in the ligation reaction. Of these, approximately half did so with the dodecanucleotide covalently joined to the genome at both 5' and 3' termini. The site of incorporation of the dodecamer was mapped to the expected 36-base region delimited by the recognition sites of XbaI and HindIII. The cis-[Pt(NH3)2(d(GpG]] cross-link completely inhibited StuI cleavage, which was fully restored following incubation of the platinated genome with cyanide to remove platinum as [Pt(CN)4]2-. Gradient denaturing gel electrophoresis of a 289-base-pair fragment encompassing the site of adduction revealed that the presence of the cis-[Pt(NH3)2(d(GpG]] cross-link induces localized weakening of the DNA double helix. In addition, double- and single-stranded genomes, in which the cis-[Pt(NH3)2(d(GpG]] cross-link resides specifically in the plus strand, were constructed. Comparative studies revealed no difference in survival between platinated and unmodified double-stranded genomes. In contrast, survival of the single-stranded platinated genome was only 10-12% that of the corresponding unmodified single-stranded genome, indicating that the solitary cis-[Pt(NH3)2(d(GpG]] cross-link is lethal to the single-stranded bacteriophage. 相似文献
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The economics of a process for the production of ethanol employing a hollow fiber extractive fermentor have been investigated. A computer simulation of the process incorporating a mathematical model of the fermentor was used to calculate the mass and energy balances. The results of the process simulation were read into a computer spreadsheet programmed with the economic calculations from which a final ethanol product cost was obtained. The process was found to be as competitive as conventional fermentation processes even at the currently high cost--$4/sq ft--of hollow fibers. It was determined that the 1986 price of 46.2 cents/L of ethanol produced by the process would be reduced by 1.8 cents/L for every $1/sq foot drop in the price of hollow fibers. A comparison of this process with conventional fermentation processes indicates that its potential savings lie in its ability to use a concentrated sugar feed, and the fermentor's increased productivity and ability to produce a concentrated ethanol stream which is removed by the extracting solvent. 相似文献
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Ahmadi Fakhrieh Nazari Farzad Ghaderi Naser Teixeira da Silva Jaime A. 《Journal of Plant Growth Regulation》2023,42(1):168-182
Journal of Plant Growth Regulation - Salinity stress is one of the most important global problems that afflicts and limits the growth and development of turfgrass in arid and semi-arid areas.... 相似文献
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Naderi Gharehgheshlagh Soheila Fatemi Mohammad Javad Jamili Shahla Nourani Mohammad Reza Sharifi Ali Mohammad Saberi Mohsen Amini Naser Ganji Fatemeh 《International journal of peptide research and therapeutics》2021,27(1):317-328
International Journal of Peptide Research and Therapeutics - Natural compounds extracted from marine organisms consisting of biological active materials like collagen provide a major source of... 相似文献
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Anthony Owusu-Sekyere Juha Kontturi Roghieh Hajiboland Somaieh Rahmat Naser Aliasgharzad Helinä Hartikainen Mervi M. Seppänen 《Plant and Soil》2013,372(1-2):541-552
Background and aims
Extensive worldwide dryland degradation calls for identification of functional traits critical to dryland plant performance and restoration outcomes. Most trait examination has focused on drought tolerance, although most dryland systems are water and nutrient co-limited. We studied how drought impacts both plant water relations and nitrogen (N) nutrition.Methods
We grew a suite of grasses common to the Intermountain West under both well-watered and drought conditions in the greenhouse. These grasses represented three congener pairs (Agropyron, Elymus, Festuca) differing in their habitat of origin (“wetter” or “drier”). We measured growth, water relations, N resorption efficiency and proficiency and photosynthetic N use efficiency in response to drought.Results
Drought decreased growth and physiological function in the suite of grasses studied, including a negative impact on plant N resorption efficiency and proficiency. This effect on resorption increased over the course of the growing season. Evolutionary history constrained species responses to treatment, with genera varying in the magnitude of their response to drought conditions. Surprisingly, habitat of origin influenced few trait responses.Conclusions
Drought impacted plant N conservation, although these responses also were constrained by evolutionary history. Future plant development programs should consider drought tolerance not only from the perspective of water relations but also plant mineral nutrition, taking into account the role of phylogeny. 相似文献9.
Moh’d A Salameh Evette S Radisky 《International Journal of Biochemistry and Molecular Biology》2013,4(3):129-139
Thirty five years ago mesotrypsin was first isolated from the human pancreas. It was described as a minor trypsin isoform with the remarkable property of near total resistance to biological trypsin inhibitors. Another unusual feature of mesotrypsin was discovered later, when it was found that mesotrypsin has defective affinity toward many protein substrates of other trypsins. As the younger sibling of the two major trypsins secreted by the pancreas, cationic and the anionic trypsin, it has been speculated to represent an evolutionary waste with no apparent function. We know now that mesotrypsin is functionally very different from the other trypsins, with novel substrate specificity that hints at distinct physiological functions. Recently, evidence has begun to emerge implicating mesotrypsin in direct involvement in cancer progression. This review will explore the biochemical characteristics of mesotrypsin and structural insights into its specificity, function, and inhibition. 相似文献
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