蕨菜黄酮分离鉴定

采用75%的乙醇提取经乙醚脱脂的蕨菜粉末,提取液回收乙醇后以石油醚、氯仿、乙酸乙酯、正丁醇依次萃取粗分段,硅胶柱层析、乙酸乙酯-甲醇系统对乙酸乙酯部位梯度洗脱,对其乙酸乙酯洗脱部分反复凝胶柱层析获得2个黄酮单体,分别鉴定为紫云英苷(1)、芦丁(2),其中化合物1为首次从蕨菜中分离得到。     

The effects of Fungi on the Gametophytes of Pteridium aquilinum (L.) Kuhn

I. The prothalli have been shown to be convenient subjects forthe study of some fungal relationships with green plants. Purecultures have been established from all the populations examinedby germination of young spores, and it has been shown that duringdormancy the number of spores which can germinate in pure culturedecreases more rapidly than the number which can germinate incultures containing contaminant fungi. Previous reports of thestimulatory effect of fungi on prothallial growth and developmenthave been confirmed and extended. 2. Prothalli growing on mineral agar have been shown to be potentiallysusceptible to the attack of a wide variety of pathogens ofhigher plants, but only two naturally occurring species of fungipathogenic to prothalli have been found during an examinationof growth on a variety of soils from bracken-infested areasin the west of Scotland. 3. The aetiology of the disease incited by Botrytis cmerca inprothalli has been shown to be similar to that of this diseasein higher plants. The pathogen is some-times restricted to lesionsof limited size around the sites of successful infections andthis is associated with changes in the cell walls of the host.A protopectinase solution prepared from a culture of germinatingspores by Brown's method induced symptoms in the prothallialcells similar to those induced by the attack of the fungus.The cell-attacking properties of the solution were greatly reducedwhen the protopectinase content was inactivated by low heatfor a short time, but they were not entirely destroyed. Thisconfirms previous indications that more than one complex maybe involved in the attack, but since the second moiety demonstratedis at least partially thermolabile the evidence does not supportjudgement of its relative significance in the attacking process.     

Long-term recovery of bracken (Pteridium aquilinum (L.) Kuhn) after asulam spraying

This paper investigates the effects of a single asulam application, sprayed from the air, on the rhizome biomass, bud density, fronds and carbohydrate reserves of bracken (Pteridium aquilinum (L.) Kuhn) using a time sequence approach. Regression models were used to investigate how these characteristics varied with time after spraying, and were used, where appropriate, to calculate the time taken for full recovery after treatment. Frond density and biomass recovered in approximately eight years, bud numbers in seven, but rhizome biomass and total carbohydrate reserves required 10 to 12 years to recover. The consequences of these results are compared with predictions from a computer model and discussed in relation to the best timing of re-treatment and the management needed for long term control.     

Ultrastructural Aspects of Sporogenesis in a Fern, Pteridium aquilinum (L.) Kuhn

The meiotic process of sporogenesis in Pteridium is accompaniedby a regular cycle of ultrastructural events. These includethe dedifferentiation and redifferentiation of organelles, andthe elimination and restoration of ribosomes. Although similarin nature to corresponding stages in other land plants, sporogenesisin Pteridium provides several unique features. During prophase the plastids pass through a stage during whichno envelope can be resolved at the periphery of the stroma.They appear to survive this period and there is no evidencethat plastid lineage is broken from primary archesporium tospore. The plastid cycle is accompanied by the presence of theiron-protein complex phytoferritin. The repopulation of the spore cytoplasm with ribosomes, followingthe prophase elimination, is achieved through the agency ofnucleoloid-like bodies. These bodies, however, are not synthesizedwithin the nucleus, but form within membrane-bound regions ofthe early prophase cytoplasm. Prophase is also characterized by the development of nuclearvacuoles, expansions of the perinuclear space, which progressivelyramify through the karyoplasm prior to the dissolution of thenuclear envelope at metaphase I. The significance of these events, their similarities with, anddifferences from, comparable stages of meiosis in other plantsare discussed. Pteridium aquilinum (L.) Kuhn, bracken, meiosis, sporogenesis     

The Effect of Colchicine on Spermatogenesis in a Fern, Pteridium aquilinum (L.) Kuhn

Treatment of developing antheridia of Pteridium aquilinum for24 h with radioactive and normal colchicine resulted in spermatocyteswith restitution nuclei, binucleate spermatocytes with multipleimmature blepharoplasts, and spermatids in which the organizationof the microtubular ribbon and basal bodies, and the shapingof the nucleus were seriously disturbed. The results indicatethat the coiling of the multilayered structure and the condensationof the chromatin, two key events in spermatogenesis, are independentof tubulin polymerization. Transitional stages were observed between the granular materialof the blepharoplast and microtubules. Colchicine affected theassembly of the cartwheel structure of the basal bodies lessthan that of the triplets, which were often rudimentary or absent.Autoradiographs were only partially successful because of thefailure to devise a satisfactory method of embedding by freeze-substitution,but there was clear evidence of colchicine binding by nucleiin young spermatocytes. Pteridium aquilinum (L.) Kuhn, bracken, spermatogenesis, colchicine     

Effects of Dimethyl Sulphoxide on the Gametophytic and Sporophytic phases of Pteridium aquilinum (L.) Kuhn

Dimethyl sulphoxide (DMSO) at concentrations of up to 10 mlper litre of growth medium was found to have no significantinfluence upon Pteridium gametophyte growth or morphology However,significant effects upon embryo development and sporophyte morphologywere shown The most striking of these was that more than oneembryo developed from each fertilized gametophyte grown on DMSOmedium Two to five embryos regularly developed on each gametophytecultured on media containing this solvent, control gametophytesbore single sporophytes The significance of these findings inrelation to theories concerning polyembryony are discussed Pteridium, dimethyl sulphoxide, polyembryony     

The differential effects of bracken (Pteridium aquilinum (L.) Kuhn) on germination and seedling performance of tree species in the African tropics

Plant Ecology - Bracken fern Pteridium aquilinum (L.) Kuhn stands act as an ecological filter that influences regeneration of other plants. Woody species are often slow to re-colonise...     

蕨菜多酚氧化酶的酶学性质

研究了蕨菜[Pteridium aquilinum (L．) Kuhn var．latiusculum (Desv．) Underw．]多酚氧化酶的动力学性质,结果表明：以邻苯二酚为底物,该酶最适pH为7．4,最适温度为25℃,60℃以上使酶迅速失活,动力学方程v=619．08[S]/(0．031 [S]),Vc、异Vc钠、NaHSO3、L-Cys可完全抑制酶活性,饱和NaCl能显著抑制酶活性,蔗糖、SDS对酶有激活作用。该酶能催化邻苯二酚、焦性没食子酸氧化,但对焦性没食子酸亲和力更强。     

蕨菜中的一个新高黄烷醇(英文)

运用柱层析等分离纯化方法,从蕨菜乙醇提取物的乙酸乙酯萃取部位中分离得到4个黄酮类化合物:3,4,6,2’,4’-五羟基高黄烷醇(1)、槲皮素3-O-β-D-葡萄糖苷(2)、芦丁(3)、槲皮素3-O-β-D-葡萄糖苷(4),其中化合物1为新化合物,也是从蕨类植物中分离出的第一个高黄烷酮,化合物2为首次从该植物中分离得到。采用MTT法对获得的黄酮类化合物的细胞毒活性测定结果表明化合物1具有明显的细胞毒活性。     

Efficacy of bracken (Pteridium aquilinum (L.) Kuhn) control treatments across a range of climatic zones in Great Britain

Bracken control field experiments were conducted at six locations across Great Britain. The effects of various cutting and herbicide management regimes upon the seasonal dynamics of bracken fronds and rhizomes were examined over a three year period. This enabled a national overview towards bracken control to be constructed. Initially, spraying with asulam was the most effective treatment in reducing frond biomass and density but was least effective in reducing rhizome biomass. Differential reductions in rhizome biomass were observed in relation to cutting frequency, with cutting twice yearly giving superior control. The national trends confirmed a number of previous observations from independent single-site studies; however, others were contradicted. Comparable management options were ranked consistently between the current and former investigation, however, the initial importance of differences in cutting frequencies did not agree between studies. This multiple-site study improves understanding of the consequences of a national bracken control programme by reducing the influence of confounding site-specific factors, and recommendations for the most appropriate bracken control techniques are made. The extent to which individual sites reflect a national trend in response to bracken control is considered and sites are compared. The hierarchy of treatments identified at the national scale was found to apply generally within individual sites. However, several responses which proved significant at the countrywide level were not so clearly defined at the site scale. Cutting once yearly was the only management regime which appeared to give different bracken control between sites. All other treatments gave similar responses between sites. This result was found in the Scottish Borders, during the second year of control, when frond biomass and density (relative to untreated plots) were greater than that recorded at other sites. This contrast was not found in subsequent monitoring. In terms of rhizome biomass depletion, poorer control was achieved following cutting once yearly at the northern sites (Mull, Scottish Borders, Lake District) compared with the southern sites (Clwyd, Breckland, Devon). The implications of experimental results are discussed in relation to increased cost effectiveness of national bracken control programmes.     

The influence of position on genet growth: a simulation of a population of bracken (Pteridium aquilinum (L.) Kuhn) genets under grazing

In a spatially explicit simulation model of vegetation dynamics (VegeTate), I labelled the initial mass of Pteridium aquilinum in each of 225 cells as a single, unique genet or clone. The physical environment was homogeneous and all genets shared the same phenotype. The aim was to discover whether and how the success of each genet was affected by its initial position relative to other genets and a competing grass species. In a scenario in which grazing generated a grass-bracken mosaic with complex spatial dynamics, the amount of growth of each genet ranged widely, from frequent extinction to mass increase by over 300 times. The main factor in the impact of position on genet growth was shown to be a benefit from the initial presence or proximity of a large mass of P. aquilinum. This was because a high density of P. aquilinum reduced local grazing intensity, allowing plant mass to accumulate and shifting the balance of competition in favour of P. aquilinum. Thus variations between cells in initial mass of P. aquilinum were greatly amplified. The implications of this amplification of initial differences between sites for population genetics are briefly discussed. Qualitative features of the spatial distribution of genets at the end of simulations matched reported observations on patchily distributed field populations of P. aquilinum. These features included dominance of a large population by a small minority of genets, widespread mixtures of a dominant genet and one or more subordinate genets, and the presence of patches of P. aquilinum formed both by agglomeration from neighbouring foci and by spread of dominant genets. Under less intense grazing, which allowed little or no development of vegetation mosaics, genet growth varied relatively little and initial variations in relative mass between genets were little changed. Based on this study, I hypothesize that any processes that generate non-linear spatial dynamics will also generate complex genet dynamics.     

Extranuptiale Nektarien. Beobachtungen anSalix eleagnos Scop. undPteridium aquilinum (L.)Kuhn.

Ohne Zusammenfassung     

Field studies of the relationship between herbivore damage and tannin concentration in bracken (Pteridium aquilinum Kuhn)

Summary The acceptance of secondary plant metabolites as herbivore deterrents rests primarily on their deleterious effects on herbivores. Efforts to demonstrate differential fitness in natural plant populations with varying concentrations of tannin have failed, since coevolved plant predators may physiologically or behaviorally circumvent the defense, which results in apparently equal amounts of damage to defended and undefended individuals. In this study, two approaches were used to overcome this difficulty. 1) Theoretically, more energy should be allocated to the defense of parts which contribute more heavily to the plant's fitness. Bracken fern clones produce fronds throughout the growing season. Fronds which are produced early should be more heavily defended than late-emerging fronds which will return less photosynthate per unit cost of production. The results of this study do not support this prediction; it appears that the production of tannin is more closely linked to environmental factors such as water stress than to date of frond emergence. Fronds which emerged in August contained as much tannin as fronds which emerged in May. 2) By recording the temporal occurrence of herbivore damage in bracken ferns, it was found that in fronds which escaped attack until after reaching maturity there was a significant negative correlation between tannin concentration in the frond and the amount of damage experienced. This result supports the generally accepted assumption that herbivory has been a selective force in the evolution of tannin as a defensive substance.     

The Nature of the Membrane Around the Egg of Peteridium aquilinum (L.) Kuhn

The mature egg of Pteridium aquilinum is surrounded by an acetolysis-resistantmembrane. Cytochemical tests indicate that this consists oflipid, possibly in a polymerized form. There is no evidencefor the presence of polysaccharide, protein, lignin, suberin,or sporopollenin. The membrane is believed to be formed frommaterials secreted by the egg itself, and to be analogous tothe inner portion of the megaspore membrane of a gymnospermwhich has a comparable origin and staining properties.