转化生长因子β的生物学特性、功能及其临床应用前景

转化生长因子β是一种高度多效性,多功能性的生长与分化因子,它广泛地调节机体的生长,发育,炎症,修复和免疫等许多生理和病理过程,具有重要的生物学功能和广阔的临床应用前景。     

Simulation model of soil compaction and root growth

Soil compaction is a widespread cause of reduced plant productivity. If the effects of soil compaction on plant growth are to be reproduced in simulation models, then the processes through which compaction reduces root elongation must be expressed mathematically and then tested against experimental data. The mathematical theory by which these processes may be represented is given in the accompanying article. In this article, the behavior of a simulation model based on this theory is tested against data for root growth and soil gas concentration recorded from soil columns of which the middle layers were compacted to different bulk densities. The model was able to reproduce the failure of the root system to penetrate the compacted middle layer within the period of the experiment when bulk density exceeded 1.55 Mg m^-3. The model also reproduced decreases in O₂ concentrations, and increases in CO₂ concentrations, in the atmospheres of the compacted layer and of the uncompacted layer below it as bulk density of the compacted layer increased. The simulated time course of O₂ and nutrient uptake and of O₂ concentrations in the compacted layer at different depths is presented and its consistency with experimental findings is examined. As part of a larger ecosystem model, this model will be useful in estimating site-specific effects of soil compaction on carbon cycling in agroecosystems.     

Plant‐produced human growth hormone shows biological activity in a rat model

Plants have been shown to be efficient systems for expressing a wide range of recombinant proteins from various origins. Here, using a plant virus‐based expression vector to produce human growth hormone (hGH) in Nicotiana benthamiana plants, we demonstrate, for the first time, that the plant‐produced hGH (pphGH) is biologically active in a hypophysectomized rat model. We observed an average weight gain of ～17 g per animal in a group of 10 animals that were injected subcutaneously with pphGH with 60 μg/dose for 10 days. With the increasing demand for hGH, accompanied with the need to make this recombinant protein available to a wider population at a more reasonable cost, plants provide a feasible alternative to current production platforms. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Plant growth promotion and biological control of Pythium aphanidermatum, a pathogen of cucumber, by endophytic actinomycetes

Aims:  To evaluate the potential of Actinoplanes campanulatus , Micromonospora chalcea and Streptomyces spiralis endophytic in cucumber roots, to promote plant growth and to protect seedlings and mature plants of cucumber from diseases caused by Pythium aphanidermatum , under greenhouse conditions.
Methods and Results:  Three endophytic isolates, out of 29, were selected through tests aimed at understanding their mechanisms of action as biocontrol agents and plant growth promoters. When applied individually or in combination, they significantly promoted plant growth and reduced damping-off and crown and root rot of cucumber. The combination of the three isolates resulted in significantly better suppression of diseases and plant growth promotion, than where the plants were exposed to individual strains.
Conclusions:  The three selected actinomycete isolates colonized cucumber roots endophytically for 8 weeks, promoted plant growth and suppressed pathogenic activities of P. aphanidermatum on seedling and mature cucumber plants.
Significance and Impact of the Study:  The results clearly show that the endophytic, glucanase-producing actinomycetes used, especially as a combined treatment, could replace metalaxyl, which is the currently recommended fungicide for Pythium diseases in the United Arab Emirates. These endophytic isolates also have the potential to perform as plant growth promoters, which is a useful attribute for crop production in nutrient impoverished soils.     

Simulation Model of a Possible Trigger for Reversible Switching of the Stress Regime in Plants

A simulation model of a trigger mechanism that reversibly switches a plant to the stress regime in response to adverse environmental effects is suggested and investigated. This mechanism is activated by an elevated level of specific cell metabolites and, by inhibiting the customary synthetic processes, actuates the formation of systems that counteract the deregulation of plant metabolism. The operation of the postulated mechanism corresponds better to the known patterns of plant transition between the normal and stress states than the operation of common triggers. The model describes the reversibility of stress response and its relation to the intensity of environmental effects. The model also suggests that the stress response in plants is aimed at stabilizing the cell level of dangerous stress metabolites under adverse environmental conditions and providing for the termination of plant stress after cessation of the action of a stress factor. The possible actual prototypes of the model variables are discussed and used to explain several phenomena observed in plants under stress conditions, in particular, the changes in the system of prooxidant–antioxidant equilibrium.     

生物土壤结皮对准噶尔盆地5种荒漠植物幼苗生长与元素吸收的影响

生物土壤结皮广泛分布于许多干旱和半干旱地区, 它影响土壤物理过程、水文、侵蚀和养分循环过程, 从而影响植物种子萌发与生长发育。该文以新疆准噶尔盆地腹地的古尔班通古特沙漠的生物土壤结皮为研究对象, 分析了生物土壤结皮对准噶尔盆地5种荒漠植物(白梭梭(Haloxylon persicum)、蛇麻黄(Ephedra distachya)、角果藜(Ceratocarpus arenaarius)、涩芥(Malcolmia africana)和狭果鹤虱(Lappula semiglabra))的生长及其对元素吸收的影响。结果表明: 1)相对于裸沙而言, 生物土壤结皮显著促进了荒漠植物的生长速率, 并增加了草本植物地上和地下的生物量, 但对灌木的生物量无显著影响; 2)生物土壤结皮使部分一年生草本植物的开花和结实期提前, 这可能有利于荒漠植物在有限的环境资源下快速完成生活史, 并繁衍后代; 3)生物土壤结皮能够影响荒漠植物对土壤中营养元素的吸收, 具体表现在生物土壤结皮显著促进了5种植物对N的吸收, 增加了荒漠植物在N贫乏的荒漠生态系统的适应能力, 而对P和K的吸收均没有影响。生物土壤结皮对荒漠植物对元素吸收的影响因种而异, 对不同的植物有不同的影响。荒漠植物对Mg、Mn和Cu的吸收受生物土壤结皮的影响最小。     

Modeling physical growth using mixed effects models

This article demonstrates the use of mixed effects models for characterizing individual and sample average growth curves based on serial anthropometric data. These models are advancement over conventional general linear regression because they effectively handle the hierarchical nature of serial growth data. Using body weight data on 70 infants in the Born in Bradford study, we demonstrate how a mixed effects model provides a better fit than a conventional regression model. Further, we demonstrate how mixed effects models can be used to explore the influence of environmental factors on the sample average growth curve. Analyzing data from 183 infant boys (aged 3–15 months) from rural South India, we show how maternal education shapes infant growth patterns as early as within the first 6 months of life. The presented analyses highlight the utility of mixed effects models for analyzing serial growth data because they allow researchers to simultaneously predict individual curves, estimate sample average curves, and investigate the effects of environmental exposure variables. Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc.     

不同生物有机肥对连作菠萝生长及防控心腐病效果

[背景] 菠萝心腐病是菠萝生产中常见的土传病害。[目的] 促进连作菠萝的高效栽培并提高病害防效。[方法] 采集连作发病菠萝园土壤,利用盆栽实验研究3种载体（椰糠、泥炭土、菜籽饼）和生防菌株（枯草芽孢杆菌HL2、链霉菌株HL3）与商品普通有机肥共同堆制成的生物有机肥对菠萝植株生长及菠萝心腐病防控效果的影响。[结果] 与化肥处理（CK）相比,施用生物有机肥处理能促进菠萝植株的生长,显著增加鲜重（叶、茎、根）、干重（叶、茎、根）和D叶长（菠萝植株叶片束起时最长的叶片长度）;与化肥处理（CK）相比,施用生物有机肥处理均能降低菠萝心腐病发病率;施用商品普通有机肥处理（YJ）防病能力较差,而生物有机肥处理（KC）的防控效果最好,其次为生物有机肥处理（KY、KN、LY）,防控效果均为83.5%。相关分析表明,土壤病原菌（烟草疫霉菌）含量与放线菌、有机质、pH呈极显著负相关关系（p<0.001）,与土壤速效钾含量呈显著正相关关系（p<0.05）,与发病率呈显著正相关关系（p<0.01）。[结论] 施用生物有机肥可促进菠萝植株生长、降低发病率,对菠萝心腐病有较好的防效,可为菠萝产业健康发展提供参考。     

The kinetics of Lagenidium giganteum growth in liquid and solid cultures

AIMS: Production of the mosquito biolarvacide Lagenidium giganteum in solid culture has been proposed as an economic alternative to production in liquid culture because of observations of improved shelf life and efficacy upon storage. Understanding the differences between these production systems and estimating growth rate in solid culture are important for commercialization. In order to address these needs a logistic model was developed to describe the growth kinetics of L. giganteum produced in solid and liquid cultures. METHODS AND RESULTS: Kinetic parameters in the logistic model were estimated by nonlinear regression of CO2 evolution rate (CER) and biomass data from solid and liquid cultivation experiments. Lagenidium giganteum biomass was measured using DNA extracted directly from samples. The logistic model was fit to experimental biomass and CER data with low standard errors for parameter estimates. The model was validated in two independent experiments by examining prediction of biomass using on-line CER measurements. CONCLUSIONS: There were significant differences between maximum biomass density, maintenance coefficients, and specific growth rates for liquid and solid cultures. The maximum biomass density (mg dw ml-1) was 11 times greater for solid cultivation compared with liquid cultivation of L. giganteum; however, the maintenance coefficient (mg CO2 h-1 (mg dw)-1) was six times greater for liquid cultivation than in solid cultivation. The specific growth rate at 30 degrees C was approximately 30% greater in liquid cultivation compared with solid cultivation. Slower depletion of substrate and lower endogenous metabolism may explain the longer shelf life of L. giganteum produced in solid culture. SIGNIFICANCE AND IMPACT OF THE STUDY: A simple logistic model was developed which allows real-time estimation of L. giganteum biomass from on-line CER measurements. Parameter estimates for liquid and solid cultivation models also elucidated observations of longer shelf life for production in solid culture.     

角质细胞生长因子研究进展

角质细胞生长因子(KGF)从属于成纤维细胞生长因子家族。KGF基因表达受多种细胞因子调控。KGF与受体KGFR特异性的结合发挥其多种生物学功能：参与组织、器官的发育;参与皮肤、胃、肠、肾、膀胱、肺等上皮的损伤修复;减少放、化疗所带来的副作用,具有损伤防护功能;KGF与肿瘤密不可分。     

生物制剂对沙地樟子松苗木成活生长及生理特征的影响

采用Pt菌剂、ABT生根粉、HRC吸水剂和GGR 6植物生长调节剂等生物制剂,研究了不同生物制剂对2年生樟子松苗木田间试验的造林成活率、植株高度、单株生物量、细根量和盆栽试验苗木的叶片光合和水分利用效率等生理特征的影响.结果表明:(1) Pt3(3号菌剂) 、ABT (ABT生根粉)和HRC (HRC吸水剂)均显著地提高樟子松苗木的成活率,它们分别比对照处理苗木成活率高29.3%、23.6%和9.4%,而GRR (GGR植物生长调节剂)和Pt1(1号菌剂)处理苗木的造林成活率同对照处理苗木成活率差异不显著;(2) Pt3、ABT处理均显著地促进了苗木细根生长,分别比对照处理多34.72和15.18 cm,而HRC、CGR和Pt1同对照处理没有显著差异;回归分析表明细根量与苗木成活率呈显著正相关,说明生物制剂提高成活率是通过细根量的增加来实现的;(3) Pt3和ABT处理的苗木高度比对照多2.2 、1.5cm 和1.1cm,单株生物量干重分别大1.73、0.72g 和0.33g, 针叶长度、单个针叶面积和单株植株针叶数量分别多1.54和 0.096cm、0.188cm2和0.116cm2、31和23束;而Pt1和GGR处理对苗木高度和单株生物量影响不显著; (4) Pt3和ABT处理显著地提高了苗木叶片叶绿素含量和光合速率及水分利用效率等生理指标方面,而其它生物制剂对苗木生理指标影响不显著.生物制剂通过提高苗木生长量和增强生理活动提高樟子松沙地造林成活率.     

Effect of pH on biological phosphorus uptake

An anaerobic aerobic laboratory scale sequencing batch reactor (SBR) was operated to study the effect of pH on enhanced biological phosphorus removal. Seven steady states were achieved under different operating conditions. In all of them, a slight variation in the pH value was observed during anaerobic phase. However, pH rose significantly during aerobic phase. The increase observed was due to phosphorus uptake and carbon dioxide stripping. When pH was higher than 8.2-8.25 the phosphorus uptake rate clearly decreased. The capability of Activated Sludge Model No. 2d (ASM2d) and Biological Nutrient Removal Model No. 1 (BNRM1) to simulate experimental results was evaluated. Both models successfully characterized the enhanced biological phosphorus removal performance of the SBR. Furthermore, BNRM1 also reproduced the pH variations observed and the decrease in the phosphorus uptake rate. This model includes a switch function in the kinetic expressions to represent the pH inhibition in biological processes. The pH inhibition constants related to polyphosphate storage process were obtained by adjusting model predictions to measured phosphorus concentrations. On the other hand, pH inhibition should be included in ASM2d to accurately simulate experimental phosphorus evolution observed in an A/O SBR.     

Chemically defined media for growth and sporulation of Entomophthora virulenta

Amino acids, salts, and vitamins were combined with dextrose to test their effect on growth and sporulation of Entomophthora virulenta in liquid shake culture. The addition of a vitamin solution to the tested media did not enhance growth or sporulation. MgSO₄·7H₂O was the only salt individually tested that allowed for good growth and sporulation. MgSO₄·7H₂O concentrations exceeding 250 mg/liter in media lacking other salts inhibited sporulation. A simple medium of l-arginine, l-leucine, glycine, and mineral salts allowed high growth and sporulation.     

Characterization of a comparative model of the extracellular domain of the epidermal growth factor receptor

The Epidermal Growth Factor (EGF) receptor is a tyrosine kinase that mediates the biological effects of ligands such as EGF and transforming growth factor alpha. An understanding of the molecular basis of its action has been hindered by a lack of structural and mutational data on the receptor. We have constructed comparative models of the four extracellular domains of the EGF receptor that are based on the structure of the first three domains of the insulin-like growth factor-1 (IGF-1) receptor. The first and third domains of the EGF receptor, L1 and L2, are right-handed beta helices. The second and fourth domains of the EGF receptor, S1 and S2, consist of the modules held together by disulfide bonds, which, except for the first module of the S1 domain, form rod-like structures. The arrangement of the L1 and S1 domains of the model are similar to that of the first two domains of the IGF-1 receptor, whereas that of the L2 and S2 domains appear to be significantly different. Using the EGF receptor model and limited information from the literature, we have proposed a number of regions that may be involved in the functioning of the receptor. In particular, the faces containing the large beta sheets in the L1 and L2 domains have been suggested to be involved with ligand binding of EGF to its receptor.     

Population dynamics in modeling tumor growth

A new approach based on local interaction between cancer and tissue cells is applied to the problem of the onset and growth of solid tumors in homogeneous tissues and effects associated with dramatic changes in tumor growth after crossing the boundary between different tissues. The characteristic sizes and growth rates of spherical tumors, the points of the beginning and the end of spherical growth, and further development of complex structures from the spherical ones (rough interface between the tumor and the host tissue, elongate outgrowths, dendritic structures, and metastases) are inferred assuming that the reproduction rate of a population of cancer cells is a nonmonotonous function of their local concentration and thus of the local curvature of the tumor surface. The growth behavior changes dramatically when the tumor crosses a boundary between two tissues.     

Current challenges in quantitative modeling of epidermal growth factor signaling

Over the last decade, epidermal growth factor (EGF) signaling has been used repeatedly as a test-bed for pioneering computational systems biology. Recent breakthroughs in our molecular understanding of EGF signaling pose new challenges for mathematical modeling strategies. Three key areas emerge as particularly relevant: the pervasive importance of compartmentalization and endosomal trafficking; the complexity of signalosome complexes; and the regulatory influence of diffusion and spatiality. Each one of them demands a drastic change in current computational approaches. We discuss recent developments in the field that address these emerging aspects in a new generation of more realistic - and potential more useful - models of EGF signaling.     

The effect of different salts (heavy metals) on the mycelium growth of Nematophagus fungi

Environmental pollution in addition to direct damage on plant growth, with the destruction of biological control agents, causes indirect damage to plants. The aim of this research was to study the effects of different concentrations (0, 500, 1000, 1500 and 2000 ppm) of heavy metals including Ag, Co, Cu, Fe, Hg, Mn, Pb and Zn on the mycelial growth and to assess the fungicidal or fungistatic effects of these salts on five Nematophagus fungi including Trichoderma harzianum (T8), Trichoderma virens (T21), Trichoderma hamatum (T9), Pochonia chlamydosporia var. chlamydosporia and Arthrobotrys oligospora. The results show that Ag, Co, Cu, Fe and Hg could stop the mycelium growth of all fungi, but Mn, Pb and Zn cannot inhibit the growth of these fungi completely. Among the first group, Hg and Cu stopped the growth of fungi even in 500 ppm. Among these metals that inhibit the growth of fungi, Cu has fungistatic effect and others have fungicide effect. The experiment was conducted in vitro condition, using potato dextrose agar (PDA) under complete randomised design with four replications. The data of mycelium growth were recorded at seven days after inoculation at 25 ± 2°C.