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1.
Two new phototrophic consortia, “Chlorochromatium lunatum” and “Pelochromatium selenoides”, were observed and collected in the hypolimnion of several dimictic lakes in Wisconsin and Michigan (USA). The two consortia had the same morphology but different pigment composition. The cells of the photosynthetic components of the consortia were half-moon-shaped. This morphology was used to differentiate them from the previously described motile phototrophic consortia “Chlorochromatium aggregatum” and “Pelochromatium roseum”. These phototrophic cells did not resemble any described unicellular green sulfur bacteria. The predominant pigments detected were bacteriochlorophyll d and chlorobactene for the green-colored “Clc. lunatum”, and bacteriochlorophyll e and isorenieratene for the brown-colored “Plc. selenoides”. Their pigment compositions and the presence of chlorosomes attached to the inner face of the cytoplasmic membrane in both kinds of photosynthetic cells confirmed this new half-moon-shaped morphotype as a green sulfur bacterium. Both consortia were found thriving in lakes with low concentrations of sulfide (< 60 μM), below the layers of “Clc. aggregatum” and “Plc. roseum”. The green consortia were observed in lakes where the oxic-anoxic interface was located at shallow depths (2–7 m), while the brown consortia were found at greater depths (8–16 m). The two newly described consortia were never detected together at the same depth in any lake. Received: 30 April 1997 / Accepted: 17 January 1998  相似文献   

2.
Concentrations of trans-resveratrol were analyzed in 36 Korean-grown grape cultivars, including cv. Kyoho. This cultivar has large irregular berries and a deep-black skin and accounts for >15% of all grapevines grown in Korea. The content of trans-resveratrol is an important quality parameter, and its pattern of variability increased gradually until the time of harvest. Its distribution also fluctuated significantly among leaves, seeds, and exocarps, with the highest amount (1,477 μg g−1 dry weight) occurring in the leaves. Among all cultivars evaluated here, trans-resveratrol contents were significantly higher in “Cheongsoo” and “High Bailey,” their levels being 50% above the overall mean (i.e., 2.0-mg g−1 dry weight), whereas 14 cultivars had contents that were 10% less than that mean value  相似文献   

3.
J Xie  L Tang  Z Wang  G Xu  Y Li 《PloS one》2012,7(7):e41502
In resource-poor environments, adjustment in plant biomass allocation implies a complex interplay between environmental signals and plant development rather than a delay in plant development alone. To understand how environmental factors influence biomass allocation or the developing phenotype, it is necessary to distinguish the biomass allocations resulting from environmental gradients or ontogenetic drift. Here, we compared the development trajectories of cotton plants (Gossypium herbaceum L.), which were grown in two contrasting soil textures during a 60-d period. Those results distinguished the biomass allocation pattern resulting from ontogenetic drift and the response to soil texture. The soil texture significantly changed the biomass allocation to leaves and roots, but not to stems. Soil texture also significantly changed the development trajectories of leaf and root traits, but did not change the scaling relationship between basal stem diameter and plant height. Results of nested ANOVAs of consecutive plant-size categories in both soil textures showed that soil gradients explained an average of 63.64-70.49% of the variation of biomass allocation to leaves and roots. Ontogenetic drift explained 77.47% of the variation in biomass allocation to stems. The results suggested that the environmental factors governed the biomass allocation to roots and leaves, and ontogenetic drift governed the biomass allocation to stems. The results demonstrated that biomass allocation to metabolically active organs (e.g., roots and leaves) was mainly governed by environmental factors, and that biomass allocation to metabolically non-active organs (e.g., stems) was mainly governed by ontogenetic drift. We concluded that differentiating the causes of development trajectories of plant traits was important to the understanding of plant response to environmental gradients.  相似文献   

4.
植物的生长特性随环境条件的变化具有可塑性,而不同的环境因素对植物可塑性的影响也不尽相同。利用异速分析的方法,通过模拟退化草地恢复过程中猪毛菜(Salsola collina)的不同种群密度(16、44、100、400株/m2),研究其形态结构性状及生物量分配策略的异速关系在种群密度间的差异。结果表明,种群密度增大能抑制猪毛菜的生长,而且对猪毛菜的株高、根长、一级分枝数、二级分枝数、三级分枝数以及总分枝长均产生了极显著的影响,表明种群密度的变化使得植物的高生长和侧向生长发生了显著变化。种群密度的变化也引起了植物生物量的变化,其中植物根、茎、叶间的生物关系是一种表观可塑性,植物的生长策略未发生改变,只是植物个体大小发生改变引起的生物量分配的变化。植物株高、总分枝长、一级分枝数及繁殖分配的变化,是由种群密度变化引起的,植物的适应策略发生了改变,是真正的可塑性。种群密度改变了植物的繁殖分配策略,而未改变植物叶的分配策略,说明当环境发生变化时,植物调整了其繁殖策略以适应环境因素的改变,以保证种群的生存繁衍。  相似文献   

5.
6.
A new species of notothenioid fish, Pogonophryne bellingshausenensis n. sp., is described from the Bellingshausen Sea, Antarctica. The new species belongs to the dorsally-spotted “mentella” group of the genus and is characterized by having a short (about 13% SL) mental barbel with a short (about 16% of barbel length), narrow (barely wider than the stalk), and relatively inconspicuous terminal expansion composed of short, irregular, fingerlike processes. Compared to most other dorsally-spotted species of Pogonophryne (“barsukovi”, “marmorata”, and “mentella” groups), P. bellingshausenensis has a relatively wide (about 7% SL) interorbital region. An unspotted patch on the median dorsal surface of the head, posterior to the posttemporal ridges and anterior to the first dorsal fin, has not been observed previously in any dorsally-spotted species. The holotype was collected at 1,947 m, one of the deepest records for any species of Pogonophryne. A revised key to the ten species of the “mentella” group of Pogonophryne is also provided.  相似文献   

7.
We compared the phenotypic plasticity of two greenhouse-grown species (Corispermum macrocarpum and Salsola collina) occupying different positions in a successional sequence in Horqin Sandy Land, by treating with different population density and the availability of soil nutrients and water. The same species can exhibit different patterns of plasticity in response to different environmental factors. In the soil nutrient treatments, the plasticity pattern of S. collina could be described as “master-of-some”. However, in the soil-water and population-density treatments, it showed no significant difference from C. macrocarpum in the reaction norm for plasticity. It was similar to a “jack-of-all-trades” plasticity pattern. Contrary to the previous conclusion that late successional species had higher reproductive allocation than early successional species, in this successional sequence, the late species had lower reproductive allocation in all treatments. Reproductive allocation of both species increased with the increase in water availability and also increased with a decrease in nutrient levels. However, density had no effect on reproductive allocation. Although the root:shoot ratio increased with decreasing water availability, there were no differences in the plasticity pattern for this trait in both species. Root:shoot ratio was, however, not significantly affected by nutrient availability and density. In a word, the plasticity patterns of invaders are adapted to the analyses of succession.  相似文献   

8.
Under conditions of a few behavioral tests on rats, we examined the psychotropic activity of novel N-uronoyl derivatives of amino acids: (i) N-(1,2:3,4-di-O-isopropylidene-α-D-galactopyranuronoyl-β-alanine (DAGU-Ala), (ii) DAGU-glycyl-D,L-glutamic acid (DAGU-Gly-Glu), and (iii) DAGU-glycyl-glycine (DAGU-Gly-Gly) injected i.p. in a 50 mg/kg dose. In an open-field test, DAGU-Gly-Glu and DAGU-GLy-Gly showed antistress properties (they decreased the intensity of locomotion, decreased the number of defecation acts, and intensified the research activity), while DAGU-Ala possessed a psychostimulating effect (intensification of locomotor and research activity and an increase in the number of defecations). In the “black-and-white chamber” test, only DAGU-Gly-Gly exerted an anxiolytic effect; it somewhat increased the frequency and duration of emergings of animals from the dark section and duration of visits to the illuminated section of the chamber. DAGU-GLy-Glu manifested antidepressant properties; it increased the time of active swimming of the animal in the Porsolt test and decreased the duration of passive “hanging” of rats in the “suspension by the tail” test. Neirofiziologiya/Neurophysiology, Vol. 39, No. 1, pp. 52–61, January–February, 2007.  相似文献   

9.
The neuropharmacological profile of 4-phenyl-1-[4-(2-naphtalimido)butyl]-piperazine (PNBP), a compound that possesses a high affinity for the serotonin receptors of 1A-type (5-HT1A) and lacks an anxiolytic action, has been studied. Intracerebral administration of PNBP to rats through implanted cannulae into the hippocampal region resulted in no substantial behavioral changes during “open field” and “conflict situation” tests, as compared with those of control animals. At the same time, the behavioral effects of intraperitoneal administration of 10 mg/kg buspirone were completely abolished if buspirone had been jointly administered with 10 mg/kg PNBP. Moreover, combined application of 0.3 mg/kg PNBP and 0.3 mg/kg 8-OH-DPAT, an agonist of 5-HT1A receptors, almost completely abolished the components of “serotonin syndrome” (prone position and stamping of the forepaws) in animals under study. These findings allowed us to conclude that PNBP has the properties of a competitive antagonist of buspirone and 8-OH-DPAT.  相似文献   

10.
Aluminium concentration was analyzed in roots, stems and leaves of species growing in morichals with extreme flooded acid soils, deficient in K, Ca, Mg and P. Mean aluminium saturation was 73%. Results seem to indicate that species depending on seasonal changes in the Al concentration of plant compartments, could be grouped into “perennial aluminium accumulators”, “late aluminium accumulators” and “threshold aluminium accumulators”.  相似文献   

11.
The allometry of greenhouse‐grown Salsola collina Pall. in response to variation in soil nutrient content, water supply and population density has been compared. The results showed that the biomass allocation was size‐dependent. Root, stem, leaf and reproductive allocation showed a ‘true’ plasticity in response to soil nutrient variation. At low soil nutrient content, plants tended to allocate more biomass to the development of reproductive organs than to stem and leaf, but root allocation was consistent due to a tradeoff between the effects of plant size and soil nutrient content. The plasticity of stem allocation and reproductive effort was ‘true’, while the plasticity of root allocation was ‘apparent’, but there was no plasticity for leaf allocation in response to soil water variation. At lower soil water content, plants tended to allocate more biomass to the stem than to development of reproductive organs. With the exception of ‘apparent’ plasticity of root allocation, no plasticity was detected in biomass allocation when population density was varied.  相似文献   

12.
Pseudocercospora griseola is the causal agent of angular leaf spot of common bean (ALS). It has undergone parallel coevolution with its host and two major groups have been defined, “Andean” (P. griseola f. griseola) and “Mesoamerican” (P. griseola f. mesoamericana). The aim of this study was to analyze the nature and the level of the dark pigment synthesized by the representatives of each group. After 21 days of incubation on potato dextrose agar medium, P. griseola f. griseola isolate S3b developed colonies with diameters of 17.5 ± 1.3 mm and concentric rings of pigmentation. Isolate T4 of P. griseola f. mesoamericana presented smaller colonies (9.9 ± 0.3 mm) with a uniform dark-gray color. Both isolates, S3b and T4, produced the same pigment, a 1,8-dihydroxynaphthalene-melanin, although different in quantity and structural features as suggested by the IR spectrum. The P. griseola f. griseola isolate S3b had a higher growth rate and melanin content as well as smaller sensitivity to melanin synthesis inhibitors compared to the isolate T4 of P. griseola f. mesoamericana. These results suggest a possible link between melanin and growth in P. griseola.  相似文献   

13.
Summary Plasticity of plant traits is commonly quantified by comparing different phenotypes at the same age. In this paper, we present a method in which the effect of resource conditions on plant weight is used as a basis for quantifying the plasticity of individual plant traits. Abutilon theophrasti individuals were grown in, and some transferred between, high and low intensity light conditions, resulting in four phenotypes. Plant traits were found to exhibit different degrees of plasticity, decreasing in this order: height; specific leaf area; allocation to branch roots; allocation to leaf area; number of nodes; allocation to tap roots; allocation to stem; allocation to leaf weight. Under these conditions, individuals of the four phenotypes had very similar heights when compared at the same age, but very different heights when compared at the same plant weight. The latter comparison indicates that light intensity influences height independently of its influence on plant weight. Individuals that were transferred from high to low light had greater allocation that had not been transferred, but individuals of all phenotypes had nearly the same leaf weight allocation when compared at the same plant weight. The latter comparison indicates that light intensity influeces leaf weight allocation mostly by influencing plant weight. In the phenotype resulting from the transfer of plants from low to high light, reproduction was stimulated much less than plant weight and axillary leaf growth, and reproductive allocation was delayed relative to the other three phenotypes. We conclude that when plasticity is measured by comparing phenotypes at the same plant weight, the effects of resources on plant size can be excluded from the quantification.  相似文献   

14.
The systematics and taxonomy of Kappaphycus and Eucheuma (Solieriaceae) is confused and difficult due to morphological plasticity, lack of adequate characters to identify species and commercial names of convenience. These taxa are geographically widely dispersed through cultivation. Commercial, wild and herbarium sources were analysed; molecular markers provided insights into taxonomy and genetic variation, and where sources of genetic variation may be located. The mitochondrial cox2-3 and plastidal RuBisCo spacers were sequenced. There is a clear genetic distinction between K. alvarezii (“cottonii”) and K. striatum (“sacol”) samples. Kappaphycus alvarezii from Hawaii and some samples from Africa are also genetically distinct. Our data also show that all currently cultivated K. alvarezii from all over the world have a similar mitochondrial haplotype. Within Eucheuma denticulatum (“spinosum”) most African samples are again genetically distinct. Our data also suggest that currently cultivated E. denticulatum may have been “domesticated” several times, whereas this is not evident for the cultivated K. alvarezii. The present markers used do not distinguish all the morpho-types known in cultivation (e.g. var. tambalang, “giant” type) but do suggest that these markers may be useful to assess introductions and species identification in samples.  相似文献   

15.
Phenotypic plasticity is an important plant trait associated with invasiveness of alien plants that reflects its ability to occupy a wide range of environments. We investigated the phenotypic response of Chenopodium murale to resource variability and ontogeny. Its plant-level and leaf-level traits were studied at high-resource (HR) and low-resource (LR) sites in peri-urban areas in Indian dry tropics. Plants at LR had significantly higher root length, root/shoot biomass ratio, stem mass and root mass fractions. Plants at HR had higher shoot length, basal diameter, leaf mass fraction and leaf area ratio. Leaf-level traits like leaf area and chlorophyll a were also higher here. Mean plasticity indices for plant- and leaf-level traits were higher at HR. With increasing total plant biomass, there was significant increase in the biomass of leaf, stem, root, and reproductive parts, and root and shoot lengths, whereas root/shoot length ratio, their biomass ratio, and leaf and root mass fractions declined significantly. Allocation to roots and leaves significantly decreased with increasing plant size at both sites. But, at any size, allocation to roots was greater at LR, indicative of optimization of capture of soil nutrients, whereas leaf allocation was higher at HR. Consistently increasing stem allocation equaled leaf allocation at comparatively higher shoot lengths at HR. Reproductive biomass comprised 10–12% of the plant’s total biomass. In conclusion, the success of alien weed C. murale across environmentally diverse habitat conditions in Indian dry tropics can be attributed to its high phenotypic plasticity, resource utilization capability in low-resource habitats and higher reproductive potential. These characteristics suggest that it will continue to be an aggressive invader.  相似文献   

16.
高寒草甸高原早熟禾个体性状对放牧与围封的响应   总被引:1,自引:0,他引:1  
植物对放牧的响应是植物在响应过程中为生存和繁殖所形成的适应策略,研究植物表型反应对揭示草原生态系统的放牧响应机制具有重要意义。以青藏高原高寒草甸主要植物高原早熟禾(Poa alpigena)为研究对象,通过放牧和围封试验,研究其个体性状对放牧与围封的响应,旨在为草原生态系统放牧机制提供理论依据。结果表明:1)在长期放牧干扰下,除叶片数和根重外,其他性状株高、分枝数、叶长、叶宽、叶面积、茎粗、茎长、根长、根粗、穗长、总叶质量、单叶质量、茎重、穗重、全株重均出现显著变小的特征(P0.05);而短期围封对于高原早熟禾叶长、叶宽、总叶质量、单叶质量、茎重、穗重、根重等功能性状的恢复效果并不显著(P0.05),表明放牧退化草原植物性状具有保守性;2)通过构建高原早熟禾性状可塑性变化谱,发现穗重、茎重、全株重、分蘖数、茎长、株高等可塑性幅度较大,为放牧响应的敏感指标,叶片数、叶宽、茎粗、根粗的可塑性变化幅度较小,为惰性性状。  相似文献   

17.
 Seed output is determined by two processes: resource acquisition and the allocation of resources to seeds. In order to clarify how the reaction norm of seed output is controlled by the phenotypic expression of its two components, we examined the genetic components of plasticity of seed dry mass, plant size, and reproductive allocation under different conditions of soil nutrient availability and conspecific competition among eight families of Abutilon theophrasti. Without competition, the reaction norm of seed mass of the families crossed between the lowest and other nutrient levels, although neither of its components, plant size and reproductive allocation, showed such a response. The crossing reaction norm (i.e., reversal of relative fitnesses of different genotypes along the environmental gradient) of seed mass resulted from (1) a trade-off between plant size and reproductive allocation, and (2) changes in the relative magnitude of genetic variances in plant size and reproductive allocation with soil nutrient availability. While allocation was more important in determining seed mass under limiting nutrient conditions, plant size became more important under high-nutrient conditions. There were no significant genetic variances in seed mass, plant size, and reproductive allocation in the competition treatment, except at the highest nutrient level. The results show that plant competition mitigated the effects of genetic differences in plant performance among the families. We discuss the results in relation to maintenance of genetic variation within a population. Received: 16 August 1996 / Accepted 26 April 1997  相似文献   

18.
Japanese monkeys often exchange the particular vocal sound, “coo,” especially when they feed or move as a group. It was considered that the “coo” sound had no positive social meaning, perhaps because the “coo” sound network and its function were hidden behind other behavioral observations. For identification of the vocalizer only from hearing the “coo” sound, three phonetic values, i.e., the “fundamental,” “duration,” and “formants,” plus other characteristics were used as indices of voiceprints. The results indicated that these were effective for identifying the vocalizer in two-thirds of the adults in the study troop which was composed of 12 adults and 16 immature members. The “coo” sound exchange network among the troop members (adults) was drawn on the basis of the voiceprint identification. The network showed three characteristics as follows: (1) matriarchs of the kin-groups frequently exchanged “coo” sounds with each other; (2) the other females exchanged “coo” sounds mostly within their own kin-groups; and (3) males seldom participated in the “coo” sound exchange. This suggests that “coo” sound exchange plays a central role for the matriarch of kin-groups in binding each kin-group and, ultimately, in binding all members together into an organized troop.  相似文献   

19.
While mowing‐induced changes in plant traits and their effects on ecosystem functioning in semi‐arid grassland are well studied, the relations between plant size and nutrient strategies are largely unknown. Mowing may drive the shifts of plant nutrient limitation and allocation. Here, we evaluated the changes in nutrient stoichiometry and allocation with variations in sizes of Leymus chinensis, the dominant plant species in Inner Mongolia grassland, to various mowing frequencies in a 17‐yr controlled experiment. Affected by mowing, the concentrations of nitrogen (N), phosphorus (P), and carbon (C) in leaves and stems were significantly increased, negatively correlating with plant sizes. Moreover, we found significant trade‐offs between the concentrations and accumulation of N, P, and C in plant tissues. The N:P ratios of L. chinensis aboveground biomass, linearly correlating with plant size, significantly decreased with increased mowing frequencies. The ratios of C:N and C:P of L. chinensis individuals were positively correlated with plant size, showing an exponential pattern. With increased mowing frequencies, L. chinensis size was correlated with the allocation ratios of leaves to stems of N, P, and C by the tendencies of negative parabola, positive, and negative linear. The results of structure equation modeling showed that the N, P, and C allocations were co‐regulated by biomass allocation and nutrient concentration ratios of leaves to stems. In summary, we found a significant decoupling effect between plant traits and nutrient strategies along mowing frequencies. Our results reveal a mechanism for how long‐term mowing‐induced changes in concentrations, accumulations, ecological stoichiometry, and allocations of key elements are mediated by the variations in plant sizes of perennial rhizome grass.  相似文献   

20.
以内蒙古锡林河流域沿水分梯度分布的灰脉苔草(Carex appendiculata)、贝加尔针茅(Stipa baicalensis)、羊草(Leymus chinensis)、大针茅(Stipa grandis)、小叶锦鸡儿(Caragana microphylla)和冷蒿(Artemisia frigida) 6个草地群落为对象, 研究了围封禁牧与放牧样地中144个共有植物种的高度、丛幅面积、茎、叶和株(丛)生物量、茎叶比等性状。结果表明: 1)在个体水平上, 放牧样地中植物的生殖枝高度、营养枝高度、丛幅面积、单株(丛)生物量、茎、叶生物量和茎叶比均显著低于围封禁牧样地, 植物在放牧干扰下表现出明显的小型化现象; 2)在群落水平上, 放牧亦显著降低了群落总生物量和茎、叶生物量; 3)过度放牧显著改变了物种的资源分配策略, 使生物量向叶的分配比例增加, 向茎的分配比例减少。资源优先向同化器官分配可能是植物对长期放牧干扰的一种重要适应对策; 4)轻度放牧对物种的资源分配没有显著影响, 单株(丛)生物量和群落茎、叶及总生物量均表现出增加趋势, 这与过度放牧的影响正好相反。过度放牧引起的植物个体小型化改变了生态系统中物种的资源分配策略, 进而对生态系统功能产生重要的影响。  相似文献   

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