Mg2+对灰树花菌丝体生长的影响

研究了不同浓度的Mg^2 对灰树花菌丝体生长的影响,结果表明:2—3g/L的Mg^2 浓度对菌丝体生长有明显的促进作用。浓度过高,则抑制菌丝体生长。     

灰树花液体深层培养工艺研究

对灰树花进行了液体深层培养试验,结果表明：液体培养基碳源以豆粉+麸皮、玉米粉+麸皮和氮源以蛋白胨、牛肉膏等较适宜菌丝生长的物质,确定了灰树花深层培养的液体培养基配方;并研究了培养条件对菌丝生物量的影响,得出了培养液pH在5．30～6．00和通气量为1：(1．00～1．40)的条件下,菌丝生物量达到最大。     

灰树花多糖的分子修饰及其活性研究进展

灰树花是一种高蛋白低脂肪的食品,具有免疫调节、抗氧化和抗肿瘤等生物活性。其中,多糖是灰树花的主要活性成分之一。对多糖进行分子修饰是提高它原有的生物活性或增加新活性的重要途径之一。综述了灰树花多糖的分子修饰方法,以及修饰后灰树花多糖的生物活性及其构效关系的研究进展,以期为灰树花多糖的深入研究和开发利用提供参考。     

莱芜灰树花生物学特性研究

目的:测定掌握莱芜灰树花野生菌株的生物学特性,为其开发利用提供科学依据。方法:采用组织分离法和菌丝尖端纯化技术分离纯化菌种;采用生长速率法测定其生长适宜条件。结果:该野生菌株的菌丝体生长的最适温度为28℃;最适pH值为5.5;在被测的11种碳源和7种氮源中,最佳碳源为甘露糖,最佳氮源为(NH4)2SO4;KH2PO4对菌丝体的生长具有明显的促进作用,促进效果达223.64%;培养料最适含水量为65%;子实体生长发育温度24~30℃,平均转化率为66.37%。结论:莱芜灰树花野生菌株为转化率中等的高温型株系。     

灰树花深层发酵培养基的研究

灰树花具有较宽广的碳源谱和氮源谱,其最佳碳源为马铃薯汁加葡萄糖,最佳氮源为麸皮。在有生长促进剂一板栗壳煮汁作用下,菌丝的增产率达１４０％。培养基的氮源种类和生长促进剂对菌丝生长具显著的影响,两者交互作用明显。培养基中碳源浓度过高不利于菌丝的生长。灰树花深层发酵的较佳培养基为ＱＦ培养基：葡萄糖６０９,ＫＨ_２ＰＯ_４ ｌｇ,ＭｇＳＯ_４ ０．５ｇ,ＣａＣｌ_２ ０．１ｇ板栗壳煮汁 １５０ｇ,水１Ｌ。     

灰树花活性多糖构效关系研究进展

灰树花是一种珍贵的食药用菌,具有降血糖、抗肿瘤、免疫调节和抗病毒等多种生物活性。灰树花多糖是其主要的活性成分,多糖的生物活性与多糖的结构密切相关。本文综述了从20世纪80年代起国内外已报道的灰树花活性多糖的结构表征。部分研究认为多糖的降血糖活性可能与β-1,6-葡聚糖主链化学结构相关,而灰树花多糖结构为β-1,6主链或β-1,3主链葡聚糖时具有较好的抗肿瘤活性。然而多糖结构异常复杂,精细结构的解析困难,导致目前灰树花多糖结构表征一般止步于单糖组成、分子量、糖苷键类型、分支结构和粗略分子链构象,但二维核磁(two dimensional nuclear magnetic resonance,2D-NMR)和高分辨质谱联用等技术的发展将有助于解开灰树花多糖构效关系,并为灰树花活性多糖的开发利用提供理论依据。     

灰树花子实体多糖D-组分的提取、硫酸化及免疫测定

从灰树花(Maitake)子实体中提取分离得到子实体多糖D组分,并分别考察了提取中的几个关键因素对D组分得率的影响,包括加水倍数、浸提时间、醇沉浓度、浓缩倍数。然后,对D组分进行了硫酸化修饰,得到了两种不同取代度的硫酸化多糖。最后,研究了灰树花多糖D组分及硫酸化灰树花多糖D组分对小鼠的免疫器官重量、腹腔巨噬细胞吞噬功能、血清溶血素形成及淋巴细胞转化率的影响。结果表明,在10mgkg剂量下,灰树花多糖D组分及硫酸化灰树花多糖D组分具有免疫增强作用,并且在合适的取代度下硫酸化灰树花多糖D组分比灰树花多糖D组分表现了更强的免疫调节作用。     

灰树花胞外多糖对四氯化碳致小鼠肝损伤的保护作用

四氯化碳可导致小鼠急性肝损伤,采用灰树花胞外多糖(GFP)防治后,对其血清中丙氨酸氨基转移酶(ALT),天门冬氨酸氨基转移酶(AST)和过氧化氢酶活力(CAT)以及肝组织匀浆中的丙二醛(MDA)和乳酸脱氢酶(LDH)进行测定,与模型组相比较,灰树花胞外多糖治疗组ALT、AST、MDA、LDH活力明显降低,而CAT活力明显升高。通过组织切片染色可以直观的看出灰树花胞外多糖能显著减轻肝组织病理变化程度。结果显示GFP对CCL4致小鼠急性肝损伤具有保护作用。     

灰树花漆酶酶学性质的初步研究

漆酶是一种具有广泛应用前景的多功能酶,但能否大规模工业化生产成了制约其应用开发的主要瓶颈之一。担子菌类真菌是分泌漆酶的主要来源之一,灰树花隶属于担子菌,但有关其分泌漆酶的研究鲜有报道。本文初步探讨了pH值、温度及不同阴、阳离子等因素对灰树花孢外漆酶酶学特性的影响,结果表明灰树花孢外漆酶最适反应pH值为2.2,最适反应温度65℃,且反应体系中缓冲液的组成也会影响灰树花漆酶的活性。灰树花漆酶具有较强的热稳定性,但反应体系中若存在卤族离子则会强烈抑制灰树花漆酶的活性。本研究为今后开发利用灰树花漆酶提供了借鉴。     

灰树花孔菌超微粉体内抗肿瘤作用研究

通过研究肿瘤抑制率、脏器指数、肿瘤切片的观察以及血清中影响因子干扰素-γ（IFN-γ）、白细胞介素-2（IL-2）、血管内皮细胞生长因子（VEGF）、过氧化氢酶（CAT）、谷胱甘肽-过氧化物酶（GSH-PX）和超氧化物歧化酶（SOD）等指标的变化对比分析灰树花孔菌 Grifola frondosa子实体粗粉及灰树花孔菌子实体超微粉对Hep-A-22荷瘤小鼠体内抗肿瘤和免疫调节作用。结果表明,各剂量组分均具有抑制肿瘤生长作用,其中灰树花孔菌超微粉高剂量组（1 500mg/kg）抑瘤效果最佳,与模型组比较有极显著性差异（ P<0.01）。通过HE染色后的肿瘤细胞可观察到坏死面积增大,同时该组血清中IFN-γ、IL-2、VEGF、GSH-PX和SOD含量显著增加（ P<0.01或 P<0.05）,并与抑制肿瘤具有一定相关性。     

A unifying theory of refractive error development

While retinal defocus is believed to be myopigenic in nature, the underlying mechanism has remained elusive. We recently constructed a theory of refractive error development to investigate its fundamental properties. Our Incremental Retinal-Defocus Theory is based on the principle that the change in retinal-defocus magnitude during an increment of genetically-programmed ocular growth provides the requisite sign for the appropriate alteration in subsequent environmentally-induced ocular growth. This theory was tested under five experimental conditions: lenses, diffusers, occlusion, crystalline lens removal, and prolonged nearwork. Predictions of the theory were consistent with previous animal and human experimental findings. In addition, simulations using a MATLAB/SIMULINK model supported our theory by demonstrating quantitatively the appropriate directional changes in ocular growth rate. Thus, our Incremental Retinal-Defocus Theory provides a simple and logical unifying concept underlying the mechanism for the development of refractive error.     

Dynamical modeling of drug effect using hybrid systems

Drug discovery today is a complex, expensive, and time-consuming process with high attrition rate. A more systematic approach is needed to combine innovative approaches in order to lead to more effective and efficient drug development. This article provides systematic mathematical analysis and dynamical modeling of drug effect under gene regulatory network contexts. A hybrid systems model, which merges together discrete and continuous dynamics into a single dynamical model, is proposed to study dynamics of the underlying regulatory network under drug perturbations. The major goal is to understand how the system changes when perturbed by drugs and give suggestions for better therapeutic interventions. A realistic periodic drug intake scenario is considered, drug pharmacokinetics and pharmacodynamics information being taken into account in the proposed hybrid systems model. Simulations are performed using MATLAB/SIMULINK to corroborate the analytical results.     

A dual-mode dynamic model of the human accommodation system

The function of the accommodation system is to provide a clear retinal image of objects in the visual scene. The system was previously thought to be under simple continuous (i.e., single mode of operation) feedback control, but recent research has shown that it is under discontinuous (i.e., two stimulus-dependent modes of operation) feedback control by means of fast and slow processes. A model using MATLAB/SIMULINK was developed to simulate this dual-mode behavior. It consists of fast and slow components in a feedback loop. The fast component responds to step target disparity with an open-loop movement to nearly reach the desired level, and then the slow component uses closed-loop feedback to reduce the residual error to an acceptable small level. For slow ramps, the slow component provides smooth tracking of the stimulus, whereas for fast ramps, the fast component provides accurate staircase-like step responses. Simulation of this model using a variety of stimuli, including pulse, step, ramp, and sinusoid, showed good agreement with experimental results. Thus, this represents the first dynamic model of accommodation that can accurately simulate the complex dual-mode behavior seen experimentally. The biological significance of this model is that it can be used to quantitatively analyze clinical deficits such as amblyopia and accommodative insufficiency.     

细菌视紫红质的两种光电微分响应及其机制

利用MATLAB软件对细菌视紫红质 (BR)膜光电器件的脉冲响应实验数据进行拟合 ,得到器件的冲激响应函数。据此用SIMULINK模块构造出了反映BR光电器件特性的仿真系统。利用此系统对不同间断光入射BR光电器件时的输出响应信号进行了仿真计算。通过分析得出结论 :以前所描述的微分响应 (发生在毫秒到秒的时间量级 ,在光打开时产生一个正脉冲 ,在光关掉时产生一个负脉冲 )并非BR分子固有的特性 ,部分是由于测量电路引起的。BR分子本身特性引起的微分响应是发生在微秒时间量级 ,而且在光打开时产生一个负脉冲 ,在光关掉时产生一个正脉冲。对这两种微分响应产生的机制分别进行了探讨     

黄土丘陵半干旱区柠条林株高生长过程新模型

黄土丘陵半干旱区柠条林的株高生长不随时间单调增加,在生长末期因生长动力小于生长阻力,株高随时间小幅度减小。采用宁夏固原上黄生态站柠条林的生长观测资料,以经典Logistic方程为基础,添加了生长阻力因素,建立了柠条林生长的改进模型,使得生长速率在生长末期出现负值;并以高密度柠条成林多年生长观测数据为依据,建立了连年生长模型。用数学建模和统计检验的方法对数据进行处理,其结果表明,改进模型较Logistic方程具有更高的拟合度和相关系数。建立的模型与传统生长方程不同,由于微分方程中引入了阻力因子,故生长曲线中存在极值坐标且不具有严格单调性。将多年的株高生长曲线综合到一个坐标系内后,新模型中位置参数a与内禀生长率b的比值随着生长呈现逐渐增大的趋势。改进模型的生长顶点出现在8月,与柠条林株高的实际生长过程吻合;计算了新模型的生长顶点与生长期结束时的株高的差值,并将该值记为生长损失。由于柠条林的灌丛较为矮小,在越冬时干梢现象对株高的影响不可忽略,该过程导致生长方程中第二年初始点小于第一年最末点;在考虑了该现象后所建立的连年生长模型中,2002年和2003年干稍现象的终止点位于2月,与植物生长的节律吻合。本研究为描述半干旱区灌木林生长过程提供了依据。     

Modeling surface growth of Escherichia coli on agar plates

Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34 degrees C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves.     

Modeling Surface Growth of Escherichia coli on Agar Plates

Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H.Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34°C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves.     

冷却猪肉中气单胞菌生长预测模型的建立和检验

为探讨冷却猪肉中气单胞菌的生长规律,将气单胞茵接种到经过80℃无菌水灭菌的冷却猪肉中,构建Gompertz和Baranyi初级模型来描述气单胞菌在不同温度下的生长状况。结果表明：修正的Gompertz模型对气单胞菌生长曲线的拟合效果优于Baranyi模型,R2均在0．97以上。应用平方根模型和Arrhenius模型对由修正的Gompertz模型得出的最大比生长速率进行拟合,所得平方根模型拟合效果略优于Arrhenius模型。实验所建二级模型能预测0-35℃贮藏条件下气单胞菌的生长。     

Scale-Up of flat plate photobioreactors considering diffuse and direct light characteristics

This study investigates the scaling of photobioreactor productivity based on the growth of Nannochloropsis salina incorporating the effects of direct and diffuse light. The scaling and optimization of photobioreactor geometry was analyzed by determining the growth response of a small-scale system designed to represent a core sample of a large-scale photobioreactor. The small-scale test apparatus was operated at a variety of light intensities on a batch time scale to generate a photosynthetic irradiance (PI) growth dataset, ultimately used to inform a PI growth model. The validation of the scalability of the PI growth model to predict productivity in large-scale systems was done by comparison with experimental growth data collected from two geometrically different large-scale photobioreactors operated at a variety of light intensities. For direct comparison, the small-scale and large-scale experimental systems presented were operated similarly and in such a way to incorporate cultivation relevant time scales, light intensities, mixing, and nutrient loads. Validation of the scalability of the PI growth model enables the critical evaluation of different photobioreactor geometries and design optimization incorporating growth effects from diffuse and direct light. Discussion focuses on the application of the PI growth model to assess the effect of diffuse light growth compared to direct light growth for the evaluation of photobioreactors followed by the use of the model for photobioreactor geometry optimization on the metric of areal productivity.