杰克·伦敦&尼采式超人

分析杰克·伦敦的《海狼》《马丁·伊登》两部小说中的超人式人物,以及作家本人奋斗和悲剧中的超人色彩。

一条弱食强肉的海狼——评杰克·伦敦的《海狼》

本文从《海狼》中的主要人物赖生的形象分析入手,试论述杰克·伦敦创作此书时的思想矛盾。就文学史上两个有争议的问题提出笔者的看法:一、赖生是超人标本但其结局隐含作者对超人哲学朦胧的否定。二、作者塑造海狼赖生的手法中包含着浪漫主义、自然主义和现实主义等因素。

Effects of Sunitinib Malate on Growth of Human Bladder Transitional Cell Line T24 In Vitro

Objective To investigate the growth-inhibitory effect of sunitinib malate on human bladder transitional cell carcinoma （TCC） in vitro. Methods Human bladder TCC cell line T24 was cultured and exposed to graded concentrations of sunitinib malate for 72 hours in vitro to determine the sensitivities to drug. Cell viability was measured by MTT assay. Cell apoptotic morphology was observed by fluorescence microscope following DAPl staining. Band expressions of Fas, Fas ligand, poly （ADP-ribose） polyrnerase （PARP） and D-actin were analyzed by Western blot. Wound healing process of T24 cells exposed to sunitinib malate was assayed. Results Sunitinib malate exerted a concentration-dependent and time-dependent inhibitory effect on the T24 cell lines. Fluorescence microscopy showed that small vacuoles appeared in the nuclei of T24 cells and the vacuoles were bigger with higher drug concentrations. The expressions of Fas ligand and PARP in T24 cells treated with sunitinib malate exhibited a concentration-dependent increase. Moreover sunitinib malate suppressed the wound healing process in a concentration-dependent manner. Conclusion Sunitinib malate exerted marked inhibitory activity against bladder cancer cell line T24.

pH-Induced selective electrocatalytic hydrogenation of furfural on Cu electrodes

The efficient and selective electrocatalytic hydrogenation(ECH)of furfural is considered a green strategy for achieving biomass-derived high-value chemicals.Regulating an aqueous electrolytic environment,a green hydrogen energy source of water,is significant for improving the selectivity of products and reducing energy consumption.In this study,we systematically investigated the mechanism of pH dependence of product selectivity in the ECH of furfural on Cu electrodes.Under acidic conditions,the oxygen atom dissociated directly from hydrogenated furfural-derived alkoxyl intermediates,followed by stepwise hydrogenation until H_(2)O formation via a thermodynamically favorable proton-coupled electron transfer process,thereby inducing a high proportion of the hydrogenolysis product(2-methylfuran).However,under partial alkaline conditions,furfural could be directly hydrogenated to furfuryl alcohol(selectivity~98%)due to the high-energy barrier of the deoxidation process via a surface hydride(Had)transfer.Our results highlight the vital role of the electrolytic environment in furfural selective conversion and broaden our fundamental understanding of hydrodeoxygenation reactions in ECH.

Cellular localization and biochemical characterization of a novel calciumdependent protein kinase from tobacco

By screening tobacco cDNA library with MCK1 as a probe, we isolated a cDNA clone NtCPK5 （accession number AY971376）, which encodes a typical calcium-dependent protein kinase. Sequence analyses indicated that NtCPK5 is related to both CPKs and CRKs superfamilies and has all of the three conserved domains of CPKs. The biochemical activity of NtCPK5 was calcium-dependent. NtCPK5 had Vmax and Km of 526nmol/min/mg and 210μg/ml respectively with calf thymus histone （fraction Ⅲ, abbreviated to histone Ⅲs） as substrate. For substrate syntide-2, NtCPK5 showed a higher Vmax of 2008 nmol/min/mg and a lower Km of 30μM. The K0.5 of calcium activation was 0.04μM or 0.06μM for histone Ⅲs or syntide-2 respectively. The putative myristoylation and palmitoylation consensus sequence of NtCPK5 suggests that it could be a membrane-anchoring protein. Indeed, our transient expression experiments with wild type and mutant forms of NtCPK5/GFP fusion proteins showed that NtCPK5 was localized to the plasma membrane of onion epidermal cells and that the localization required the N-terminal acylation sites of NtCPK5/GFP. Taking together, our data have demonstrated the biochemical characteristics of a novel protein NtCPK5 and its subcellular localization as a membrane-anchoring protein.

Temperature dependent expression of cdc2 and cyclin B1 in spermatogenic cells during spermatogenesis

p34cdc2 and Cyclin B1 are key components of cell cycle controlling machine and are believed to play a fundamental role in gametogenesis. It is also well known that, in scrotal mammals, spermatogenesis depends greatly on the maintenance of comparatively low temperature in the scrotum. To investigate whether the expression of cdc2 and Cyclin B1 in spermatogenic cells during spermatogenesis is actually a temperature dependent event, in situ hybridization, Western blotting and immunohistochemistry analysis were used to study the expression of cdc2 and Cyclin B1 in normal and cryptorchid testis. Results showed that the abdominal temperature had no significant influence on the transcription of cdc2 and Cyclin B1 in the spermatogonia and pachytene/diplotene primary spermatocytes, but it blocked the translation of them. Due to the deficiency of p34cdc2 and Cyclin B1, the spermatogonia and pachytene/diplotene primary spermatocytes were unable to form MPF, hence, they couldn’t undergo karyokinesis. The development of primary spermatocytes was arrested at the G2 to M phase transition. We also found that testosterone could regulate the Cyclin B1 expression in spermatogenic cells. Muscular injection of testosterone could recover spermatogenesis in the unilateral scrotal testis which was influenced by the contralateral cryptorchid testis, but it could not salvage the spermatogenesis block in the cryptorchid testis.

Allelopathic Effects of Aqueous and Ethanolic Leaves Extracts of Schinus molle L. under Different Kinds of Pruning

Secondary metabolites produced by plants can be used in popular medicine, as well they can interact with plants and other organisms, in which case they are called allelochemicals and influence the neighboring ecosystem. This work aimed to evaluate the allelopathic effects of Schinus molle L. species widely used in reforestation and urban afforestation. Therefore, leaves of S. Molle were collected from different populations located at Alfenas and Nepomuceno in Minas Gerais, Brazil. Cypselae of lettuce （Lactuca sativa L.） were germinated in biochemical oxygen demand （BOD） chamber at 25 ℃ with a photoperiod of 12 h under different extracts concentrations. The experiment was performed in factorial design （2 × 4） with two kinds of extracts （aqueous and ethanol） and four concentrations （2.5, 5, 10 and 20 mg/mL） in randomized blocks. The variables analyzed were germination （%）, germination speed index （GS1）, % of normal seedlings, root length, fresh biomass and dry biomass. Changes in the cell cycle in meristematic cells of the used model were also evaluated. Concentration-dependent effect on all parameters was observed, with the exception of dry biomass exposed to ethanol extract. The root elongation parameter was different between the extracts even in lower concentrations, thus indicating that this is the most sensitive parameter of this species. Toxic effect from S. rnolle extracts was observed in all parameters regardless the kind of pruning management or method of extraction （water or ethanol）.

Partial Order and Extremes of Multivariate Extreme Value Distributions

This paper studies the dependence order among multivariate extreme value dis- tributions with a fixed marginal distribution. Making use of copulas to prove that the set organized by multivariate extreme value distributions and the dependence order defined in it is a partial order set. Finally, the maximum and minimum values of the set is discussed.

Influence of dietary Lys levels and dietary net energy levels on growth performance and nitrogen balance of growing pigs

Two experiments were conducted to determine the effects of L y s ine（Lys） and Net Energy （NE） levels on growth performance （Exp. I） and N balance （Exp. 2） in growing pig. In Exp. 1, 36 castrated pigs [21.35 -4- 0.55 kg of body weight （BW）] were allotted to six treatments with six replicates per treatment. Pigs were fed two levels of Lys （low and high） and three levels of NE （low, med, or high） in a 2×3 factorial arrangement. The experiment lasted for 35 d. There were no effects of dietary Lys and NE on pig performance （P〉0.05, but a Lys×NE interaction in ADG was observed （P〈0.05）. In Exp. 2, 24 pigs were used to determine the effects of diet in Exp. 1 on pig N balance. Neither Lys nor NE level affected N retention （g/d） （P〉0.0）. Lys×NE interaction in N retention （g/d） （P〈0.01） and in N apparent biological value （ABV） （P〈0.05） was observed. Pigs fed the low Lys diet had lower serum urea nitrogen （SUN） concentrations compared with the high Lys treatment （P〈0.01）. Pigs fed the med-NE diet had lower SUN concentrations compared with the pigs fed the low-NE diet （P〈0.1）. These results suggest that pigs from 21 kg to 50 kg BW fed diets containing 0.83% standardized ileal digestible Lysine and 2351 Kcal of NE/kg had maximum ADG and N retention.

Excess Levels of ILysine and Threonine in Low Protein, Wheat-based Diets on Serum Amino Acid Concentrations and Performance of Growing Pigs

Two experiments were conducted to evaluate the growth response and serum concentrations （SC） of amino acids （AA） in pigs fed wheat-based diets with either deficient, adequate or excess Lys and Thr. Previously, the standardized ileal digestibilities of AA in a basal diet were determined with five ileal cannulated pigs in a digestion trial. In experiment 1, 21 pigs （12.5±0.91 kg） were used to evaluate the effect of adding 0%, 0.69%, and 1.38% free L-Lys. The best growth response was obtained with 0.69% added L-Lys, equivalent to 1.05% total in the diet. The SC of Arg, Thr, and Val were lower （P 〈 0.05） in pigs fed the Lys adequate diet, compared to the deficient, but no further change occurred with excess Lys （P 〉 0.10）. Lys SC increased with each increment in the dietary Lys content （P 〈 0.05）. In experiment 2, 20 pigs （14.3 ± 1.57 kg） were used, and the addition of 0%, 0.14%, 0.28%, and 0.42% crystalline Thr, to the 0.69% L-Lys-supplemented basal diet, was evaluated. The best response was obtained with added 0.28% L-Thr, （0.66% total Thr）, but excess Thr reduced feed intake and growth rate. Moderate and excess levels of Yhr increased the SC of Thr, but excess reduced those of Va[ and Lys. These data show that excess Thr, but not Lys, affect the performance of growing pigs. Also, these data indicate that Val may become limiting in low protein diets with excess Lys or Thr.

The Content of Selenium and Other Ten Chemical Elements in Boletus Edulis from Bulgaria and Inhibition of Lipid Peroxidation

The goal of this study was to determine the content of such biological active metals as Se, Hg, AI, Cu, Zn, As, Cd, Pb, Mg, Ca and Fe in Boletus Edulis mushrooms and to study the effect of mushrooms as inhibitors of blood serum copper-initiated lipid peroxidation. The metals content was determined by ICP-OES technique and blood lipids peroxidation in vitro was assessed by thiobarbituric acid-reactive substances measurement. The dependency between quality and content of the determined biological active metals has been traced. Samples were analyzed of wild growing mushrooms Boletus Edulis from two mountain regions in Bulgaria. On the average the content of Se in Boletus Edulis was found to be 25 mg/kg dried mushroom, this content being higher in tubules than in fleshy part. We found that Boletus Edulis mushrooms inhibited lipid peroxidation in the concentration dependent manner. The effective concentration of Boletus Edulis is in 5 times lower compared to the concentration of Cantharellus Cibarius resulting in similar lipid peroxidation inhibition. This effect can be explained by 56 times higher content of Se and by 1.5 and 3 times lower content of such initiators of lipid peroxidation as Cu and Fe in Boletus Edulis compared to Cantharellus Cibarius. A system with a source of infrared radiation heating, developed by authors, was used for the mushroom mineralization. We conclude that Boletus Edulis is an effective inhibitor of blood lipid peroxidation and in 5 times stronger rather than Cantharellus Cibarius.

Drought adaptability of phreatophytes:insight from vertical root distribution in drylands of China

Aims The vertical distribution of plant roots is a comprehensive result of plant adaptation to the environment.Limited knowledge on fine vertical root distributions and complex interactions between roots and environmental variables hinders our ability to reliably predict climatic impacts on vegetation dynamics.This study attempts to understand the drought adaptability of plants in arid areas from the perspective of the relationship between vertical root distribution and surroundings.Methods By analyzing root profiles compiled from published studies,the root vertical profiles of two typical phreatophytes,Tamarix ramosissima and Populus euphratica,and their relationships with environmental factors were investigated.A conceptual model was adopted to link the parameter distribution frequency with plant drought adaptability.Important Findings The strong hydrotropism(groundwater-dependent)and flexible water-use strategy of T.ramosissima and P.euphratica help both species survive in hyperarid climates.The differences in the developmental environments between T.ramosissima and P.euphratica can be explained well by the different distribution characteristics of root profiles.That is,higher root plasticity helps T.ramosissima develop a more efficient water-use strategy and therefore survive in more diverse climatic and soil conditions than P.euphratica.We conclude that the higher variation in root profile characteristics of phreatophytes can have greater root adaptability to the surroundings and thus wider hydrological niches and stronger ecological resilience.The inadequacy of models in describing root plasticity limits the accuracy of predicting the future response of vegetation to climate change,which calls for developing process-based dynamic root schemes in Earth system models.

Secretome profiling reveals temperature-dependent growth of Aspergillus fumigatus

Aspergillus fumigatus is a ubiquitous opportunistic fungus. In this study, systematic analyses were carried out to study the temperature adaptability of A. fumigatus. A total of 241 glycoside hydrolases and 69 proteases in the secretome revealed the strong capability of A. fumigatus to degrade plant biomass and protein substrates. In total, 129 pathogenesis-related proteins detected in the secretome were strongly correlated with glycoside hydrolases and proteases. The variety and abundance of proteins remained at temperatures of 34°C–45°C. The percentage of endo-1,4-xylanase increased when the temperature was lowered to 20°C, while the percentage of cellobiohydrolase increased as temperature was increased, suggesting that the strain obtains carbon mainly by degrading xylan and cellulose, and the main types of proteases in the secretome were aminopeptidases and carboxypeptidases. Only half of the proteins were retained and their abundance declined to 9.7% at 55°C. The activities of the remaining β-glycosidases and proteases were merely 35% and 24%, respectively, when the secretome was treated at 60°C for 2 h. Therefore, temperatures >60°C restrict the growth of A. fumigatus.

Discovery and application of 6π-azaelectrocyclization to natural product synthesis and synthetic biology

While elucidating the inhibitory mechanism of a hydrolytic enzyme by aldehyde-containing natural product,we discovered a reaction involving a rapid 6π-azaelectrocyclization of azatrienes generated from aldehyde with lysine residues.The electrocyclic reaction of the 1-azatriene system,a cyclization precursor,exhibited a significant substituent effect.Asymmetric chiral piperidine synthesis and a one-pot library synthesis of pyridines on solid-supports were applied to synthesize pyridine/indole alkaloid-type natural product.Additionally,we developed lysine-based labeling and engineering of biomolecules and living cells based on the rapid 6π-azaelectrocyclization.Both labels and oligosaccharide structures were introduced efficiently and selectively into surface lysines under the mild conditions;notable effects of N-glycans on proteins and living cells were visualized for the first time by PET and noninvasive fluorescence imaging.

Interaction between curcumin and mimetic biomembrane

Curcumin, a major bioactive compound in turmeric, has a broad spectrum of antioxidant, anticarcinogenic, antimutagenic and anti-inflammatory properties. At the molecular level, curcumin modulates many structurally unrelated membrane proteins through several signaling pathways. Curcumin has been suggested to change the properties of cell membranes and affect the membrane-bound proteins indirectly; however, the detailed mechanism has yet to be investigated. In this paper, self-assembled bilayer lipid membranes are artificially constructed on the surface of a gold electrode to miinic biomembranes, and interaction between the supported membranes and curcumin is studied electrochemically. Results show that curcumin interacts with the membranes strongly, in a concentration-dependent manner. At low concentrations, curcumin tends to insert into the outer monolayer only, while at high concentrations, it may also begin to penetrate the inner monolayer. The results obtained in this work may enhance our understanding of the effect of curcumin, and possibly flavonoids, on ceU membranes and membrane proteins.

Mining of a streptothricin gene cluster from Streptomyces sp.TP-A0356 genome via heterologous expression

Streptothricins (STs) are used commercially to treat bacterial and fungal diseases in agriculture. Mining of the sequenced microbial genomes uncovered two cryptic ST clusters from Streptomyces sp. C and Streptomyces sp. TP-A0356. The ST cluster from S. sp. TP-A0356 was verified by successful heterologous expression in Streptomyces coelicolor M145. Two new ST analogs were produced together with streptothricin F and streptothricin D in the heterologous host. The ST cluster was further confirmed by inactivation of gene stnO, which was proposed encoding an aminomutase supplying -lysines for the poly-β-Lys chain formation. A putative biosynthetic pathway for STs is proposed based on bioinformatics analyses of the ST genes and experimental evidence.

Hydraulic pressure inducing renal tubular epithelial-myofibroblast transdifferentiation in vitro

Objective： The effects of hydraulic pressure on renal tubular epithelial-myofibroblast transdifferentiation （TEMT） were investigated. Methods： We applied hydraulic pressure （50 cmH2O） to normal rat kidney tubular epithelial cells （NRK52E） for different durations. Furthermore, different pressure magnitudes were applied to cells. The morphology, cytoskeleton, and expression ofmyofibroblastic marker protein and transforming growth factor-β1 （TGF-β1） of NRK52E cells were examined. Results Disorganized actin filaments and formation of curling clusters in actin were seen in the cytoplasm of pressurized cells. We verified that de novo expression α-smooth muscle actin induced by pressure, which indicated TEMT, was dependent on both the magnitude and duration of pressure. TGF-β1 expression was significantly upregulated under certain conditions, which implies that the induction of TEMT by hydraulic pressure is related with TGF-β1. Conclusion： We illustrate for the first time that hydraulic pressure can induce TEMT in a pressure magnitude- and duration-dependent manner, and that this TEMT is accompanied by TGF-β1 secretion.

On the existence of traveling wave solutions and upper and lower bounds for some Fisher-iolmogorov type equations

In this paper, we use a dynamical systems approach to prove the existence of traveling waves solutions for the Fisher-Kolmogorov density-dependent equation. Moreover, we prove the existence of upper and lower bounds for these traveling wave solutions found previously. Finally, we present a particular example which has several applications in the mathematical biology field.

Numerical simulation of physiologically relevant pulsatile flow of blood with shear-rate-dependent viscosity in a stenosed blood vessel

Pulsatile flow of blood in a blood vessel having time-dependent shape （diameter） is inves-tigated numerically in order to understand some important physiological phenomena in arteries. A smooth axi-symmetric cosine shaped constriction is considered. To mimic the realistic situation as far as possible, viscosity of blood is taken to be non-uniform, a shear-thinning viscosity model is considered and a physiologically relevant pulsatile flow is introduced. Taking advantage of axi-symmetry in the proposed problem, the stream function-vorticity formulation is used to solve the governing equations for blood flow. Effect of different parameters associated with the problem on the flow pattern has been investigated and disparities from the Newtonian case are discussed in detail.

COEVOLUTIONARY DYNAMICS OF PREDATOR-PREY INTERACTIONS

In this paper, with the method of adaptive dynamics, we investigate the coevolution of phenotypic traits of predator and prey species. The evolutionary model is constructed from a deterministic approximation of the underlying stochastic ecological processes. Firstly, we investigate the ecological and evolutionary conditions that allow for continu- ously stable strategy and evolutionary branching. We find that evolutionary branching in the prey phenotype will occur when the frequency dependence in the prey carrying capacity is not strong. Furthermore, it is found that if the two prey branches move far away enough, the evolutionary branching in the prey phenotype will induce the sec- ondary branching in the predator phenotype. The final evolutionary outcome contains two prey and two predator species. Secondly, we show that under symmetric interactions the evolutionary model admits a supercritical Hopf bifurcation if the frequency depen- dence in the prey carrying capa.city is very weak. Evolutionary cycle is a likely outcome of the nmtation-selection processes. Finally, we find that frequency-dependent selection can drive the predator population to extinction under asymmetric interactions.