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1.
Two new lanostane triterpenes, ganorbifoins A and B (1-2), together with the known compound (25S,3′S)-(+)-12α-hydroxy-3α-(3′-hydroxy-4′-methoxycarbonyl-3′-methylbutiryloxy)-24-methyllanosta-824-(31)-dien-26-oic acid (3) were isolated from the cultivated fruiting bodies of Ganoderma orbiforme. The structures of isolates were determined by extensive analysis of NMR and HRESIMS. All compounds induced glucose uptake in zebrafish-based system at the concentration of 10 μM. And the best performing compound is ganorbifoin A. Compounds 2 and 3 exhibited an inhibitory effect on nitric oxide production in LPS-induced BV-2 microglia cells at the concentration of 20 μM.  相似文献   

2.
A new 3,4-seco-27-norlanostane triterpene, ganoboninketal D (1), a new lanostane, (24S)-3-oxo-7α,24,25-trihydroxylanosta-8-ene (2), together with six known lanostanes (38), were isolated from cultivated fruiting bodies of the basidiomycete Ganoderma orbiforme. The structures were elucidated on the basis of NMR spectroscopic and mass spectrometry data, and the structures 1 and 2 were further confirmed by chemical correlations to ganoboninketal C and ganodermanondiol, respectively. All isolated compounds were inactive in the antitubercular and antimalarial activity assays against Mycobacterium tuberculosis H37Ra and Plasmodium falciparum K1, respectively, except that compound 8 exhibited weak antitubercular activity (MIC 50 μg/ml).  相似文献   

3.
4.
Epigenetics is receiving growing attention in the plant science community. Epigenetic modifications are thought to play a particularly important role in fluctuating environments. It is hypothesized that epigenetics contributes to plant phenotypic plasticity because epigenetic modifications, in contrast to DNA sequence variation, are more likely to be reversible. The population of decrease in DNA methylation 1-2 (ddm1-2)-derived epigenetic recombinant inbred lines (epiRILs) in Arabidopsis thaliana is well suited for studying this hypothesis, as DNA methylation differences are maximized and DNA sequence variation is minimized. Here, we report on the extensive heritable epigenetic variation in plant growth and morphology in neutral and saline conditions detected among the epiRILs. Plant performance, in terms of branching and leaf area, was both reduced and enhanced by different quantitative trait loci (QTLs) in the ddm1-2 inherited epigenotypes. The variation in plasticity associated significantly with certain genomic regions in which the ddm1-2 inherited epigenotypes caused an increased sensitivity to environmental changes, probably due to impaired genetic regulation in the epiRILs. Many of the QTLs for morphology and plasticity overlapped, suggesting major pleiotropic effects. These findings indicate that epigenetics contributes substantially to variation in plant growth, morphology, and plasticity, especially under stress conditions.  相似文献   

5.
SYNOPSIS. Morphological and physiological plasticity is oftenthought to represent an adaptive response to variable environments.However, determining whether a given pattern of plasticity isin fact adaptive is analytically challenging, as is evaluatingthe degree of and limits to adaptive plasticity. Here we describea general methodological framework for studying the evolutionof plastic responses. This framework synthesizes recent analyticaladvances from both evolutionary ecology and functional biology,and it does so by integrating field experiments, functionaland physiological analyses, environmental data, and geneticstudies of plasticity. We argue that studies of plasticity inresponse to the thermal environment may be particularly valuablein understanding the role of environmental variation in theevolution of plasticity: not only can thermally-relevant traitsoften be mechanistically and physiologically linked to the thermalenvironment, but also the variability and predictability ofthe thermal environment itself can be quantified on ecologicallyrelevant time scales. We illustrate this approach by reviewinga case study of seasonal plasticity in the extent of wing melanizationin Western White Butterflies (Pontia occidentalis). This reviewdemonstrates that 1) wing melanin plasticity is heritable, 2)plasticity does increase fitness in nature, but the effect variesbetween seasons and between years, 3) selection on existingvariation in the magnitude of plasticity favors increased plasticityin one melanin trait that affects thermoregulation, but 4) themarked unpredictability of short-term (within-season) weatherpatterns substantially limits the capacity of plasticity tomatch optimal wing phenotypes to the weather conditions actuallyexperienced. We complement the above case study with a casualreview of selected aspects of thermal acclimation responses.The magnitude of thermal acclimation ("flexibility") is demonstrablymodest rather than fully compensatory. The magnitude of geneticvariation (crucial to evolutionary responses to selection) inthermal acclimation responses has been investigated in onlya few species to date. In conclusion, we suggest that an understandingof selection and evolution of thermal acclimation will be enhancedby experimental examinations of mechanistic links between traitsand environments, of the physiological bases and functionalconsequences of acclimation, of patterns of environmental variabilityand predictability, of the fitness consequences of acclimationin nature, and of potential genetic constraints.  相似文献   

6.
树突棘是神经元之间产生直接联系的部位,其形态可塑性是记忆的结构基础。谷氨酸信息传递是中枢神经信息传递的主要方式,能产生突触传递效率的可塑性,由此引起树突棘形态的可塑性变化。本文从谷氨酸受体途径的角度对树突棘形态可塑性的调控机制做一综述。谷氨酸受体主要通过其下游信号分子调节棘内肌动蛋白动力学蛋白,参与树突棘的形态发生和稳定。该作用在局部受到不同的蛋白、信号分子、激素、mi RNAs的调节,从而参与生理及病理过程。最后,提出展望,研究脑区特异的局部微环境变化对记忆相关疾病病因及治疗探讨有参考价值。  相似文献   

7.
5种入侵植物补偿反应及其形态可塑性比较   总被引:2,自引:0,他引:2  
通过模拟刈割试验,研究了5种外来入侵植物(黑麦草、空心莲子草、三叶鬼针草、薇甘菊和胜红蓟)的补偿能力及其形态可塑性。结果表明:多数植物的补偿能力与形态可塑性有一定相关性,刈割和非刈割条件下空心莲子草和薇甘菊都具有较强的形态可塑性,其补偿指数较高,分别为1.65和1.27;多年生黑麦草和三叶鬼针草的形态可塑性在刈割条件下得到增强,补偿指数分别为1.44和1.28;刈割条件下胜红蓟的形态可塑性变化不大或有所降低,其补偿指数最低,为0.82。研究认为,5种植物具有不同的限制其形态可塑性和补偿能力比较理想的刈割时期,薇甘菊攀援生长方式下为30d前和60d后,空心莲子草为60d后,胜红蓟为40~50d,鬼针草为30d前,黑麦草为40~50d。  相似文献   

8.
Two species of Ganoderma belonging to different subgenera which cause disease on oil palms in PNG are identified by basidiome morphology and the morphology of their basidiospores. The names G. boninense and G. tornatum have been applied. Significant pleiomorphy was observed in basidiome characters amongst the specimens examined. This variation in most instances did not correlate well with host or host status. Spore morphology appeared uniform within a species and spore indices varied only slightly. G. tornatum was found to have a broad host range whereas G. boninense appears to be restricted to palms in Papua New Guinea.  相似文献   

9.
10.
SYNOPSIS: Growth studies of mammalian jaw muscles and studiesdetermining the degree of plasticity of these muscles are few.There are questions concerning the degrees and types of morphologicaland physiological change occurring in these muscles during normalgrowth and the ability of external forces to modify this growthprocess. There are also questions on the effects of sensoryloss on muscle growth and on changes in the motor system asthese muscles change. In this report, questions are proposedand hypotheses presented that deal with these areas relativeto the jaw muscles. It is suggested that (1) changes in themorphology and function of jaw muscles during growth vary regionallyand are related to the action of the muscle and the loadingforces imposed; (2) the degree of muscle plasticity varies regionallyand varies depending on the type of loading forces and age ofthe animal; (3) loss of sensory input during the growth of thejaw muscles would produce marked changes in the histochemicalprofile, the distribution of motor neurons, and the activitypattern of these muscles; and (4) organization of the trigeminalmotor nucleus changes as the jaw muscles grow and may also changein response to sensory loss or application of different typesof loading forces. In addition, possible approaches to thesequestions are discussed.  相似文献   

11.
Tea green leafhopper is one of the most dominant pests in major tea production regions of East Asia. This species has been variously identified as Empoasca vitis (Goëthe), Jacobiasca formosana (Paoli) and Empoasca onukii Matsuda in Mainland China, Taiwan and Japan, respectively. Recent study of DNA sequence data suggested that treatment of this pest as different species in these three adjacent regions is incorrect and that they were a single species; but the correct scientific name for the species has remained unclear. Consistent with the prior molecular evidence, morphological study shows that the male genital characters of Chinese specimens are the same as those of specimens from Japan, so the correct scientific name of tea green leafhopper in China is Empoasca (Matsumurasca) onukii Matsuda.  相似文献   

12.
白花蛇舌草是我国重要的传统中药,主要是指茜草科(Rubiaceae)钮扣草族(Spermacoceae)的Oldenlandia diffusa,但伞房花耳草(O.corymbosa)在民间或中药市场也常被作为替代品使用。由于长期以来Hedyotis-Oldenlandia复合群的分类存在许多争论,因此白花蛇舌草有时被归入非洲耳草属(Oldenlandia L.),有时又作为广义耳草属(Hedyotis L.s.l.)的成员。为了澄清白花蛇舌草命名上的问题,基于7个叶绿体片段和2个核基因片段对钮扣草族85个分类群进行了系统发育分析。结果表明,白花蛇舌草不属于以上两属中的任何一属,而应为蛇舌草属[Scleromitrion(WightArn.)Meisn.]的成员。依此结果,对5种植物进行了新组合,并提供了白花蛇舌草和伞房花耳草的形态学比较,以有助于在实践中更好地进行区分。  相似文献   

13.
长江中下游平原和东北三江平原是我国最大的两个冲积平原,其内河流、浅水湖泊和沼泽众多,菱属植物种类丰富。本研究基于对这两个区域中菱属野生植物的广泛调查,采集其居群42个,分属于9种(细果野菱、四角刻叶菱、四角菱、菱、丘角菱、东北菱、四角大柄菱、八瘤菱、四瘤菱),3变种(四角矮菱、南昌格菱、短四角菱)。进一步对采集的菱属野生植物16个分类性状进行测量和统计,并对其形态学性状的可塑性变异及分类学价值进行分析和评价。结果显示:依据菱角的果体大小、果喙性状可以将采集的菱属野生植物划分成两个类群,其中A类群仅包括细果野菱和四角刻叶菱,而其余的菱属植物7种3变种组成B类群;对有腰角组(5种2变种)的腰角性状进行聚类分析,也可将细果野菱和四角刻叶菱与其他菱属植物区分开来;而瘤突、叶和气囊性状的分类价值有限。说明果体大小、果喙和腰角性状的形态学特征是菱属植物分类和鉴定的主要依据。  相似文献   

14.
Dicotyledons are polarly organised in several ways. In plant morphology polarity, a principle allowing comparison of different plant structures has until yet not been studied. A division** of the vegetative plant in shoot and root as polar structures leads to the distinction of four instead of three basic organs: leaf, shoot axis, root axis and root cap together with the root hairs. The flower is also polarly organised, its poles are formed by the carpels and the stamens. The foliage leaves are also polarly organised which is reflected by the morphological relationship of foliage leaf, stamen and carpel. The stamen uses the hypophyll*** as base of construction and the carpel uses the epiphyll**** as base of construction. Hypophyll and epiphyll are the two poles of the foliage leaf. Root and shoot, the polar entities of the vegetative plant and stamen and carpel, the polar entities of the generative plant, are morphologically correlated. Stamen and carpel can be understood as a combination of the basic organs of vegetative and generative parts of the plant. The basic organs of the generative plant are pollen grain and embryo sack with their gametophytes. The quantitative comparison of variable proportions is supplemented by a qualitative comparison of polarities. The result is, that the organisation type of the dicotyledons can yet be understood as constituted of morphological related parts.* in german Grundorgane** in german: Gliederung*** in german: Unterblat**** in german: Oberblatt  相似文献   

15.
Clarification of fruit juice with chitosan   总被引:2,自引:0,他引:2  
Chitosan prepared from shrimp shell was made partially water-soluble by hydrolyzing with 7% acetic acid. This chitosan at low concentration was found to be effective in the clarification of different fruit juices. Appearance and acceptability of the juices after treatment with chitosan significantly increased on a nine point Hedonic scale.  相似文献   

16.
Growth-survival trade-offs play an important role in niche differentiation of tropical tree species in relation to light-gradient partitioning. However, the mechanisms that determine differential species performance in response to light and soil resource availability are poorly understood. To examine responses to light and soil nutrient availability, we grew seedlings of five tropical tree species for 12 mo at < 2 and 18 percent full sunlight and in two soil types representing natural contrasts in nutrient availability within a lowland dipterocarp forest in North Borneo. We chose two specialists of nutrient-rich and nutrient-poor soils, respectively, and one habitat generalist. Across all species, growth was higher in high than low light and on more nutrient rich soil. Although species differed in growth rates, the ranking of species, in terms of growth, was consistent across the four treatments. Nutrient-rich soils improved seedling survival and increased growth of three species even under low light. Slower-growing species increased root allocation and reduced specific leaf area (SLA) and leaf area ratio (LAR) in response to decreased nutrient supply. All species increased LAR in response to low light. Maximum growth rates were negatively correlated with survival in the most resource-limited environment. Nutrient-poor soil specialists had low maximum growth rates but high survival at low resource availability. Specialists of nutrient-rich soils, plus the habitat generalist, had the opposite suite of traits. Fitness component trade-offs may be driven by both light and belowground resource availability. These trade-offs contribute to differentiation of tropical tree species among habitats defined by edaphic variation.  相似文献   

17.

Background

A functional role of microRNAs (miRNAs or miRs) in neoplasia and metastasis is becoming clear, and the miR-200 family has received much attention for potentially regulating tumor progression. The miRNAs of this family have been shown to suppress epithelial-mesenchymal transition, and their down-regulation in some tumors promotes invasion and metastasis. Interestingly, while miR-200 is down-regulated in some cancers, it is up-regulated in others.

Principal Findings

We show that levels of miR-200 are increased in melanoma cell lines compared to normal melanocytes and that miR-200 family members play a role in determining modes of tumor cell migration. Individual tumor cells can invade in either elongated, “mesenchymal-type” or rounded, “amoeboid-like” modes and these two modes of invasion are inter-convertible [1]. In melanoma cell lines, expression of miR-200 members does not suppress invasion but rather leads to a switch between modes of invasion. MicroRNA-200c results in a higher proportion of cells adopting the rounded, amoeboid-like mode of invasion, while miR-200a results in a protrusion-associated elongated mode of invasion. Functional target identification studies suggest that the morphological effects of miR-200c may be mediated by reduced expression of MARCKS, which has been linked to formation of cell protrusions. In contrast miR-200a reduces actomyosin contractility, a feature of rounded morphology.

Significance

Overall our findings call into question the general role of miR-200 in suppressing invasion and metastasis, and highlight novel distinguishing characteristics of individual miR-200 family members.  相似文献   

18.
19.
Olfactory receptor neurons (ORNs) convey odor information to the central brain, but like other sensory neurons were thought to play a passive role in memory formation and storage. Here we show that Notch, part of an evolutionarily conserved intercellular signaling pathway, is required in adult Drosophila ORNs for the structural and functional plasticity of olfactory glomeruli that is induced by chronic odor exposure. Specifically, we show that Notch activity in ORNs is necessary for the odor specific increase in the volume of glomeruli that occurs as a consequence of prolonged odor exposure. Calcium imaging experiments indicate that Notch in ORNs is also required for the chronic odor induced changes in the physiology of ORNs and the ensuing changes in the physiological response of their second order projection neurons (PNs). We further show that Notch in ORNs acts by both canonical cleavage-dependent and non-canonical cleavage-independent pathways. The Notch ligand Delta (Dl) in PNs switches the balance between the pathways. These data define a circuit whereby, in conjunction with odor, N activity in the periphery regulates the activity of neurons in the central brain and Dl in the central brain regulates N activity in the periphery. Our work highlights the importance of experience dependent plasticity at the first olfactory synapse.  相似文献   

20.
The plasticities of 16 characters were studied in four maize(Zea mays, L.) hybrids grown at seven equidistant spacings andat four growth stages in 1 year. Plasticity was a measure ofthe extent to which the expression of a character was modifiedby changes in plant density. The hybrids differed in their plasticitiesfor all characters studied. Furthermore, the characters of ahybrid showed different plasticities. The most plastic characterswere grain yield per plant and yield per unit area, and theleast plastic were ear row number and ear height. The hierarchyof plasticities was essentially identical in all hybrids. Thedouble-cross hybrids showed non-significantly higher mean plasticitiesthan the less heterogeneous genotypes M.C. 101 and Warwick SL209.  相似文献   

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