Mobilisation of potassium and phosphorus from iron ore by ectomycorrhizal fungi

Mutualistic roles of ectomycorrhizal (ECM) fungi have been linked to their ability to produce organic acids that aid in the dissolution of insoluble minerals in the rhizosphere. This ability of ECM fungi was utilised to investigate their potential participation in the mobilisation of nutrients such as phosphorus (P) and potassium (K) from a typical insoluble ore—iron ore. In vitro pure cultures of four different ECM fungi; Pisolithus tinctorius, Paxillus involutus, Phialocephala fortini, and Suillus tomentosus were screened for their ability to mobilise P and K from two types of non-exportable Sishen iron ore. When present in iron ore, these elements are deleterious and reduce the commercial values of the ore. Experiment was set up with different treatments that included two ore types (KGT and SK) and five particle sizes of each ore type. Results indicated the potential of the four fungi to mobilise P and K from the two iron ore types though at different levels. Ore type, particle size, organic acid production and attachment of the fungi to the iron ore were all found to play important roles in the mobilisation of nutrients from these ores.     

Production of ecdysteroids by plant cell culture of Pteridium aquilinum

Summary Cells of the fernP. aquilinum, both callus and suspension cultures, are able to produce ecdysterone, 5--OH-ecdysterone, ecdysone, ponasterone and further five unidentified ecdysteroids. Under the cultivation conditions there appears to be an overproduction of ponasterone and total ecdysteroids, in comparison to the original plant.     

蕨菜乙醇提取物的Ames试验研究

目的：研究蕨菜乙醇提取物的致突变作用,为蕨菜的开发利用提供一定依据;方法：制备蕨菜乙醇提取物,采用Ames试验方法,以50μg/皿敌克松作为诱变剂,分别添加提取物50、100、200、400、800μg/皿,统计回变菌落数;结果：受试物各剂量组回变菌落数均未超过自发回变菌落数的2倍,且无剂量-反应关系;结论：在本实验条件下,蕨菜乙醇提取物无致突变作用.     

Isolation and investigation of streptomycin resistant lines of the fernPteridium aquilinum

Summary Stable lines of gametophytic tissue of the fernPteridium aquilinum resistant to streptomycin at 1.0 mg/ml were isolated without treatment with mutagens. The lines did not exclude the antibiotic, and were not found to be profoundly different from sensitive tissue at the ultrastructural level.     

Resistance of Pteridium aquilinum to attack by non-adapted phytophagous insects

Fresh bracken Pteridium aquilinum L. Kühn or crude bracken extracts deterred 9 non-adapted phytophagous insect species from feeding or settling. Feeding deterrent activity to 5 out of 7 insect species was present in crude bracken extracts at all times over the growing season and was significantly highest in May. Sequential isolation and purification of deterrents indicated that the sesquiterpene pterosin F (6-chlorethyl-2,5,7-trimethyl-indan-1-one) occurred in sufficiently high concentrations in late May/early June bracken frond (24–28 mg/kg fresh wt) to be partially responsible for the deterrent effects of crude bracken extracts to two insect species. A number of other fractions had feeding deterrent activity, but these were not characterized or quantified.     

Vegetation development on moorland after control of Pteridium aquilinum with asulam

Abstract. A range of moorland sites in the North York Moors National Park were surveyed where Pteridium aquilinum has been sprayed once with the herbicide asulam between 1 and 7 yr before. The regeneration of both P. aquilinum and the moorland vegetation were studied. The latter was variable and much slower than reported for lowland grassland or heathland, with a large proportion of the developing plant cover consisting of mosses, especially Campylopus introflexus. This slow rate of revegetation was primarily due to the paucity of micro-sites offered for germination in dense P. aquilinum litter, the poor establishment of seedlings in this litter and its slow breakdown. The consequences of this slow and variable development of vegetation to moorland restoration are discussed.     

Sucrose Mobilisation in Sugarcane Stalk Induced by Heterotrophic Axillary Bud Growth

A theoretical high-yield sugarcane biofactory can be idealised as containing culm tissue that functions as a secondary source tissue rather than a sink. To investigate this potential process, heterotrophic axillary bud outgrowth from sugarcane (Saccharum spp. hybrids) setts was used as a model system to demonstrate that sucrose is a mobilisable carbon source. The outgrowth and subsequent biomass accumulation of axillary buds from two-eye setts of mature sugarcane stalks grown in the dark was used to measure carbon mobilisation from sett internode pith tissue. After 42 days growth 99.0 ± 0.72% of sett internode pith sucrose was depleted and 2.66 ± 0.16 g of new tissue accumulated. Comparison with a control treatment in which axillary buds were excised at day zero demonstrated that carbon mobilisation was driven by the accumulation of new biomass. Profiling of soluble carbohydrates (viz. sucrose, glucose and fructose), starch, total soluble protein, total amino nitrogen, free amino acids and total insoluble material showed that the sucrose stored in the sett internode pith was the only available carbon source of sufficient size at day zero for the observed biomass accumulation. Other metabolites mobilised were glucose, fructose and some amino acids, notably isoleucine and leucine that were depleted in shoot treatment setts at day 42.     

蕨菜黄酮对小鼠体内丙二醛含量的影响

采用硫代巴比妥酸法(TBA法)测定小鼠血清和肝组织中丙二醛(malondialdehyde,MDA)的相对含量.结果表明,蕨菜黄酮可降低小鼠血清及肝组织中MDA含量.对于血清,随着饲喂的蕨菜黄酮量的增加,MDA相对含量降低的程度越显著,150mg/kg组与300mg/kg组相比,MDA相对含量差异达到极显著水平(P＜0.01);对于肝组织,随着蕨菜黄酮量的增加,MDA相对含量逐渐降低,但当蕨菜黄酮量达到一定值(150mg/kg)后,再继续加入蕨菜黄酮量,则对MDA相对含量的影响与150mg/kg组相比无显著差异.说明在本实验条件下,饲喂蕨菜黄酮有明显改善小鼠机体代谢合成,具有清除体内氧自由基功能以及增强机体抗氧化功能等保健作用.     

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 cytoplasmic vesicles of the female reproductive cells of Pteridium aquilinum

Summary Cytoplasmic vesicles appear in conspicuous numbers during oogenesis in the fern Pteridium aquilinum. Two classes of vesicles are recognized: Golgi vesicles, of the order of 0.1 in diameter, and larger vesicles, of the order of 0.75 in diameter, apparently not derived from the Golgi apparatus. The larger vesicles are further divisible into those with mainly electron-transparent contents, and those with conspicuous amounts of electron-opaque material. Both kinds of larger vesicles are believed to be autophagic in nature, but may have different origins. Comparisons are made with the vesicles which arise during differentiation of female reproductive cells in other organisms, and the significance of the phenomenon is discussed. Acknowledgement. A grant from the Royal Society (Government Grant for Research) towards the cost of diamond knives used in this work is gratefully acknowledged.     

Mobilisation of storage reserves during germination and early seedling growth of sugar beet

The principal storage reserve of sugar beet seeds is starch, which is localised in the perisperm. Additional storage reserves include the seed proteins, albumins, globulins and glutclins, which are exclusively located in the embryo. Soluble sugars are also detectable in all the organs of the mature seed. The time-course of reserve mobilisation in the different organs of the sugar beet ( Beta vulgaris L. cv. Regina) seed during germination and early seedling growth is documented, with particular reference to changes in (a) activities of hydrolases: a-amylase, β-amylase, and α-glucosidases; (b) levels of carbohydrates and (c) proteins. Amylase activities increase substantially in both cotyledons, as well as the perisperm, whereas the increase in α-glucosidase activities is largely confined to the perisperm.     

Monoclonal antibodies to surface and cytoskeletal components of the spermatozoid ofPteridium aquilinum

Summary Detergent extracted spermatozoids of the fernPteridium aquilinum were used as mixed antigen preparations for raising monoclonal antibodies in order to obtain reagents for detecting as yet uncharacterized components of the plant cytoskeleton. Selected antibodies were studied by immunofluorescence microscopy of developing spermatids and mature spermatozoids. Some reacted directly with fixed cells, others required permeabilization treatments with cold methanol or Triton X-100. AntibodiesPas2D9 andPas6D7 bind to glycoprotein antigenic determinants that are exposed on the surface of the plasma membrane. Several antibodies interact with cytoskeletal components.Pas1D3,Pas5D8 andPas5F4 bind to the cytoskeleton of permeabilized cells including the flagella. Three react specifically with the flagellar band or associated components:Pas2G6 reacts with the whole flagellar band but shows a prominent binding to basal bodies,Pas5E2 binds exclusively to basal bodies, andPas5E7 detects mitochondria associated with the flagellar band. Cross-reactions to wheat root tip cells at different stages of the cell cycle are described inMarc andGunning (1988).Abbreviations MLS multilayered structure - MT microtubule - MAb monoclonal antibody - MAP microtubule associated protein     

Pattern of cytoplasmic DNA synthesis in somatic cells of Pteridium aquilinum

The distribution of replicating DNA in the cytoplasm of somatic cells of Pteridium aquilinum was investigated, using light and electron microscope autoradiography following incorporation of ³H-thymidine.Enzyme studies showed that over 90 % of the incorporated label occurred in DNA. In contrast to mature egg cells, at least 90 % of the labelled DNA was located in plastids and mitochondria—with very little, if any, extraorganellar DNA.Replication of chloroplast and mitochondrial DNA was continuous throughout interphase, and showed a clear increase during the nuclear S phase.The concentration of replicating DNA in mitochondria was consistently about twice that of the chloroplasts. Approx. 60 % of the cytoplasmic labelling was plastid, 40 % mitochondrial.     

New Insights into Phosphorus Mobilisation from Sulphur-Rich Sediments: Time-Dependent Effects of Salinisation

Internal phosphorus (P) mobilisation from aquatic sediments is an important process adding to eutrophication problems in wetlands. Salinisation, a fast growing global problem, is thought to affect P behaviour. Although several studies have addressed the effects of salinisation, interactions between salinity changes and nutrient cycling in freshwater systems are not fully understood. To tackle eutrophication, a clear understanding of the interacting effects of sediment characteristics and surface water quality is vital. In the present study, P release from two eutrophic sediments, both characterized by high pore water P and very low pore water iron (Fe²⁺) concentrations, was studied in a long-term aquarium experiment, using three salinity levels. Sediment P release was expected to be mainly driven by diffusion, due to the eutrophic conditions and low iron availability. Unexpectedly, this only seemed to be the driving mechanism in the short term (0–10 weeks). In the long term (>80 weeks), P mobilisation was absent in most treatments. This can most likely be explained by the oxidation of the sediment-water interface where Fe²⁺ immobilises P, even though it is commonly assumed that free Fe²⁺ concentrations need to be higher for this. Therefore, a controlling mechanism is suggested in which the partial oxidation of iron-sulphides in the sediment plays a key role, releasing extra Fe²⁺ at the sediment-water interface. Although salinisation was shown to lower short-term P mobilisation as a result of increased calcium concentrations, it may increase long-term P mobilisation by the interactions between sulphate reduction and oxygen availability. Our study showed time-dependent responses of sediment P mobilisation in relation to salinity, suggesting that sulphur plays an important role in the release of P from FeS_x-rich sediments, its biogeochemical effect depending on the availability of Fe²⁺ and O₂.