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R H Marrs - One of the best experts on this subject based on the ideXlab platform.
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woody vegetation structure of brazilian cerrado invaded by pteridium arachnoideum kaulf maxon dennstaedtiaceae
Flora, 2011Co-Authors: Raquel C Miatto, Igor Aurelio Silva, Dalva M Silvamatos, R H MarrsAbstract:Abstract Biological invasion is one of the major components of global change. In the Brazilian Cerrado, the fern Pteridium arachnoideum (neotropical Bracken) is a potentially invasive species which is expected to change the vegetation structure of savannas. We assessed effects of the dominance of P. arachnoideum on the diversity of woody Cerrado species. We compared three sites dominated by neotropical Bracken with three sites without neotropical Bracken. We used multivariate analyses of variance and rarefaction curves with confidence limits to test whether the groups of species found in invaded areas were different from those found in non-invaded ones. We also analyzed the density of individuals and species and the mean area at breast height per plot. We found significant floristic differences between the areas. The diversity and the densities in the invaded areas were lower than in non-invaded ones. However, we did not observe differences in the mean area at breast height of woody plants. Thus, the P. arachnoideum invasion is a potential threat to Cerrado biodiversity. Management efforts should be made to control the Bracken, since its dominance in the plant community may lead to impoverishment and simplification of the savanna vegetation.
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competing conservation goals biodiversity or ecosystem services element losses and species recruitment in a managed moorland Bracken model system
Journal of Environmental Management, 2007Co-Authors: R H Marrs, Robin J Pakeman, K Galtress, C Tong, E S Cox, Sabena Blackbird, T J Heyes, M Le G DucAbstract:Conservation management in Europe is often geared towards restoring semi-natural ecosystems, where the objective is to reverse succession and re-establish early-successional communities, to comply with national and international conservation targets. At the same time, it is increasingly recognised that ecosystems provide services that contribute to other, possibly conflicting policy requirements. Few attempts have been made to define these conflicts. Here, we assess some potential conflicts using a Calluna vulgaris-dominated moorland invaded by Bracken (Pteridium aquilinum) as a model system, where the current policy is to reverse this process and restore moorland. We examined impacts of Bracken control treatments on services (stocks and losses of C and mineral nutrients), litter turnover and biodiversity within a designed experiment over 7 years. Bracken litter was >2000 g m(-2) in untreated plots, and treatments reduced this quantity, and its element content, to varying degrees. Cutting twice per year was the most successful treatment in reducing Bracken litter and its element content, increasing litter turnover, and increasing both mass and diversity of non-Bracken vegetation. Diversity was greatest where Bracken litter had been reduced, but species composition was also influenced by light sheep grazing. There was a significant loss of some chemical elements from Bracken that could not be accounted for in other pools, and hence potentially lost from the system. In absolute terms large amounts of C and N were lost, but when expressed as a percentage of the total amount in the system, Mg was potentially more important with losses of almost a third of the Mg in the surface soil-vegetation system. There is, therefore, a potential dilemma between controlling a mid-successional invasive species for conservation policy objectives, especially when that species has evolved to sequester nutrients, and the negative effect of increasing environmental costs in terms of carbon accounting required, the potential input of nutrients to aquatic systems, and long-term nutrient loss. There is, therefore, a need to balance conservation goals against potential damage to biogeochemical structure and function.
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effects of the litter layer of pteridium aquilinum on seed banks under experimental restoration
Applied Vegetation Science, 2006Co-Authors: Robin J Pakeman, R H Marrs, M Le G Duc, Hugh A Mcallister, J GhorbaniAbstract:Abstract Questions: Does the litter layer of Pteridium aquilinum (Bracken) act as a barrier to certain species in the seed bank? Does Bracken control/restoration treatment affect seed transfer through the litter layer? Location: Five experiments at three sites across the UK covering two major vegetation types; acid-grassland and heath-land. Methods: At each experiment a range of Bracken control and vegetation restoration treatments were applied for about ten years. The seed bank was sampled in both the Bracken litter and the soil. The cover (%) of each species in the vegetation and the Bracken litter abundance (cover and depth) was also estimated. Results: The Bracken litter layer acts as an inert barrier as it contained a large proportion of seeds available in the litter-soil profile (38% - 67% of the total). Bracken litter depth and cover also influenced significantly the seed bank composition in both the Bracken litter and the soil. These effects were site-specific, and species-specific. The applicatio...
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the use of mixtures of sulfur and Bracken litter to reduce ph of former arable soils and control ruderal species
Restoration Ecology, 2001Co-Authors: K.m. Owen, R H MarrsAbstract:High soil pH has been highlighted as a constraint to the restoration of heathland on ex-arable land. Previous studies at the Minsmere Reserve of the Royal Society for the Protection of Birds (RSPB) in England have shown that it is possible to acidify ex-arable soils using elemental sulfur and Bracken litter, although sulfur (S) is more effective. Current recommendations suggest that 4 tS/ha need to be applied to reduce soil pH below pH 4, control vigorous ruderal species, and create conditions suitable for Calluna vulgaris (heather) establishment. However, S is relatively expensive, and as Bracken litter is moderately abundant within the reserve, it made economic sense to evaluate the potential for mixing S with Bracken to see if adequate pH reductions could be achieved at lower S rates. Accordingly an experiment was designed to test the effects of combining S (0-8 t S/ha) and Bracken litter (0-10 cm depth layers) on (1) soil pH, (2) cover of ruderal species, and (3) the developing plant community. Significant interactions were detected, especially in the period immediately after application. Where Bracken litter was applied the soil pH fell immediately; in contrast, S took at least six months to start reducing pH. Where mixtures were applied there was a synergistic effect, which produced a lower pH than the S or Bracken litter applied alone. These effects were most marked at low S application rates, between 0.5-4 t S/ha. The effects of the Bracken litter addition also reduced the growth of ruderal species in the period immediately after application, probably through a combination of acidification and physical smothering. There is, therefore, a clear potential to acidify ex-arable soils using combinations of S and Bracken litter in schemes designed to restore Calluna heathland.
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Bracken distribution in great britain strategies for its control and the sustainable management of marginal land
Annals of Botany, 2000Co-Authors: Robin J Pakeman, Mike Le G Duc, R H MarrsAbstract:Bracken is often perceived as a widespread and increasing land management problem. The pollen record of a wide range of sites in Great Britain suggests that the current abundance of Bracken is less than or, at worst, equivalent to maximum historical levels. Recently gathered data also suggest that Bracken cover is declining. Results of risk assessments of land use change, and experimental and modelling investigations into the effects of climate change are synthesized. This synthesis suggests that there is the potential for increased Bracken dominance in northern Britain, spread into new areas at high altitudes, and possible spread into areas with reduced grazing. However, this must be set against any changes in the extent of other vegetation types at the expense of Bracken. There is now a long history of Bracken control, both in Great Britain and globally. Conventional methods of control (cutting, asulam application) are well understood, but many control attempts do not result in long-term success, as control is often not followed by aftercare. Bracken control is just one part of the process to ensure a sustainable use of resources and to maintain biodiversity. A coherent strategy for Bracken control is put forward, a necessary part of which includes the restoration of vegetation and subsequent land management which takes into account an understanding of Bracken ecology.
Andrew C Povey - One of the best experts on this subject based on the ideXlab platform.
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The role of Bracken fern illudanes in Bracken fern-induced toxicities
Mutation Research-reviews in Mutation Research, 2019Co-Authors: P.j. O’connor, M.e. Alonso-amelot, Stephen A Roberts, Andrew C PoveyAbstract:Abstract Bracken fern is carcinogenic when fed to domestic and laboratory animals inducing bladder and ileal tumours and is currently classified as a possible human carcinogen by IARC. The carcinogenic illudane, ptaquiloside (PTQ) was isolated from Bracken fern and is widely assumed to be the major Bracken carcinogen. However, several other structurally similar illudanes are found in Bracken fern, in some cases at higher levels than PTQ and so may contribute to the overall toxicity and carcinogenicity of Bracken fern. In this review, we critically evaluate the role of illudanes in Bracken fern induced toxicity and carcinogenicity, the mechanistic basis of these effects including the role of DNA damage, and the potential for human exposure in order to highlight deficiencies in the current literature. Critical gaps remain in our understanding of Bracken fern induced carcinogenesis, a better understanding of these processes is essential to establish whether Bracken fern is also a human carcinogen.
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Bracken pteridium aquilinum induced dna adducts in mouse tissues are different from the adduct induced by the activated form of the Bracken carcinogen ptaquiloside
Biochemical and Biophysical Research Communications, 2001Co-Authors: Renata Nascimento De Freitas, Peter J Oconnor, A S Prakash, M Shahin, Andrew C PoveyAbstract:Following treatment with Bracken fern (Pteridium aquilinum) extract and Bracken spores a number of DNA adducts were detected by P-32-postlabeling. Three of these adducts have been described previously (Povey et al., Br. J. Cancer (1996) 74, 1342-1348) and in this study, using a slightly different protocol, four new adducts, with higher chromatographic mobility, were detected at levels ranging from 50 to 230% of those previously described, When DNA was treated in vitro with activated ptaquiloside (APT) and analysed by butanol extraction or nuclease P1 treatment, only one adduct was detected by P-32-postlabeling, This adduct was not present in the DNA from mice treated with Bracken fern or spores, suggesting either that Bracken contains genotoxins other than ptaquiloside or that the metabolism of ptaquiloside produces genotoxins not reflected by activated ptaquiloside. However, as the ATP-derived adduct has been detected previously in ileal DNA of Bracken-fed calves, species-specific differences in the metabolism of Bracken genotoxins may exist, thereby leading to differences in their biological outcomes. (C) 2001 Academic Press.
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32P-post-labelling analysis of DNA adducts formed in the upper gastrointestinal tissue of mice fed Bracken extract or Bracken spores.
British journal of cancer, 1996Co-Authors: Andrew C Povey, D Potter, P. J. O'connorAbstract:Bracken toxicity to both domestic and laboratory animals is well established and tumours are formed when rodents are treated with either Bracken extracts or Bracken spores. In this study we have administered Bracken spores and extract to mice in order to investigate whether such exposure leads to the formation of DNA adducts. DNA, isolated from the upper gastrointestinal tract and liver, was digested to 3'-nucleotides. Adducts were extracted with butanol, 32P-post-labelled, separated by thin layer chromatography (TLC) and visualised and quantified using storage-phosphor technology. A cluster of adducts was clearly seen in the DNA of the upper gastrointestinal tract, but not liver, 5 and 24 h after treatment with Bracken extract or Bracken spores. These adducts were not observed in DNA extracted from vehicle-treated animals. Whereas, after 5 h adduct levels in extract and spore-treated animals were similar, after 24 h adduct levels in the extract-treated animals had diminished by > 75%, but levels in spore-treated animals remained similar to those found after 5 h. This suggests that the DNA-reactive compounds were being released slowly from the spores, even though the spores had been sonicated before administration. Adducts were also quantified after the addition of an internal standard (deoxyinosine 3'-monophosphate) by comparing the amount of label incorporated into the adducts with that found in a known amount of the internal standard. Adduct levels using this internal standard approach were similar to those found by direct measurement of radioactivity incorporated into the adduct, indicating that the labelling of adducts was quantitative. We have tried, unsuccessfully, to synthesise ptaquiloside, the principal carcinogenic component present within Bracken. However, similar patterns of adducts were observed when two other compounds, (1-(4-chlorophenyl sulphonyl)-l-cyclopropane carbonitrile and 3-cyclopropylindeno [1,2-c] pyrazol-4-(O-methyl)oxime), which both contain a cyclopropyl ring, were administered to mice. The adducts detected in Bracken-treated animals may, thus, have arisen from ptaquiloside but, whether these adducts arise directly from the compounds and Bracken spores/extract themselves or via an indirect mechanism, remains to be determined. As Bracken-induced DNA adducts are detectable in rodent tissues by a 32P-post-labelling procedure commonly employed to investigate DNA damage in human populations, it may prove possible to apply such approaches to determine human exposure.
P. J. O'connor - One of the best experts on this subject based on the ideXlab platform.
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32P-post-labelling analysis of DNA adducts formed in the upper gastrointestinal tissue of mice fed Bracken extract or Bracken spores.
British journal of cancer, 1996Co-Authors: Andrew C Povey, D Potter, P. J. O'connorAbstract:Bracken toxicity to both domestic and laboratory animals is well established and tumours are formed when rodents are treated with either Bracken extracts or Bracken spores. In this study we have administered Bracken spores and extract to mice in order to investigate whether such exposure leads to the formation of DNA adducts. DNA, isolated from the upper gastrointestinal tract and liver, was digested to 3'-nucleotides. Adducts were extracted with butanol, 32P-post-labelled, separated by thin layer chromatography (TLC) and visualised and quantified using storage-phosphor technology. A cluster of adducts was clearly seen in the DNA of the upper gastrointestinal tract, but not liver, 5 and 24 h after treatment with Bracken extract or Bracken spores. These adducts were not observed in DNA extracted from vehicle-treated animals. Whereas, after 5 h adduct levels in extract and spore-treated animals were similar, after 24 h adduct levels in the extract-treated animals had diminished by > 75%, but levels in spore-treated animals remained similar to those found after 5 h. This suggests that the DNA-reactive compounds were being released slowly from the spores, even though the spores had been sonicated before administration. Adducts were also quantified after the addition of an internal standard (deoxyinosine 3'-monophosphate) by comparing the amount of label incorporated into the adducts with that found in a known amount of the internal standard. Adduct levels using this internal standard approach were similar to those found by direct measurement of radioactivity incorporated into the adduct, indicating that the labelling of adducts was quantitative. We have tried, unsuccessfully, to synthesise ptaquiloside, the principal carcinogenic component present within Bracken. However, similar patterns of adducts were observed when two other compounds, (1-(4-chlorophenyl sulphonyl)-l-cyclopropane carbonitrile and 3-cyclopropylindeno [1,2-c] pyrazol-4-(O-methyl)oxime), which both contain a cyclopropyl ring, were administered to mice. The adducts detected in Bracken-treated animals may, thus, have arisen from ptaquiloside but, whether these adducts arise directly from the compounds and Bracken spores/extract themselves or via an indirect mechanism, remains to be determined. As Bracken-induced DNA adducts are detectable in rodent tissues by a 32P-post-labelling procedure commonly employed to investigate DNA damage in human populations, it may prove possible to apply such approaches to determine human exposure.
Renata Nascimento De Freitas - One of the best experts on this subject based on the ideXlab platform.
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clastogenic effect of Bracken fern pteridium aquilinum v arachnoideum diet in peripheral lymphocytes of human consumers preliminary data
Veterinary and Comparative Oncology, 2003Co-Authors: R C Recouso, R Stocco Dos C Santos, Renata Nascimento De Freitas, Renato Santos, A C De Freitas, Olga Brunner, Willy Becak, Charles J LindseyAbstract:Ingestion of Bracken fern (Pteridium aquilinum v. arachnoideum) is associated with digestive tract cancer in different regions of Japan, Venezuela and Brazil. In view of reports that dietary Bracken fern causes chromosomal instability in cattle, the clastogenic effect of Bracken fern was investigated, in a preliminary study, in peripheral lymphocytes obtained from habitual consumers and a control group of non-consumers, which were carefully investigated about cancer history or family cancer history, negative in both cases, using protocols comparable to those previously described in studies in cattle raised on Bracken pastures. Cytogenetic analysis showed significant increased levels of chromosomal abnormalities, such as chromatid breaks, in cultured peripheral lymphocytes of the consumer group. There was no correlation with subjects, gender, smoking habits or alcohol consumption, and the only correlation was with prolonged exposure to dietary Bracken.
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Bracken pteridium aquilinum induced dna adducts in mouse tissues are different from the adduct induced by the activated form of the Bracken carcinogen ptaquiloside
Biochemical and Biophysical Research Communications, 2001Co-Authors: Renata Nascimento De Freitas, Peter J Oconnor, A S Prakash, M Shahin, Andrew C PoveyAbstract:Following treatment with Bracken fern (Pteridium aquilinum) extract and Bracken spores a number of DNA adducts were detected by P-32-postlabeling. Three of these adducts have been described previously (Povey et al., Br. J. Cancer (1996) 74, 1342-1348) and in this study, using a slightly different protocol, four new adducts, with higher chromatographic mobility, were detected at levels ranging from 50 to 230% of those previously described, When DNA was treated in vitro with activated ptaquiloside (APT) and analysed by butanol extraction or nuclease P1 treatment, only one adduct was detected by P-32-postlabeling, This adduct was not present in the DNA from mice treated with Bracken fern or spores, suggesting either that Bracken contains genotoxins other than ptaquiloside or that the metabolism of ptaquiloside produces genotoxins not reflected by activated ptaquiloside. However, as the ATP-derived adduct has been detected previously in ileal DNA of Bracken-fed calves, species-specific differences in the metabolism of Bracken genotoxins may exist, thereby leading to differences in their biological outcomes. (C) 2001 Academic Press.
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Bracken (Pteridium aquilinum)-Induced DNA adducts in mouse tissues are different from the adduct induced by the activated form of the Bracken carcinogen ptaquiloside.
2001Co-Authors: Renata Nascimento De Freitas, O'connor P. J., Prakash A. S., Shahin M., Povey A. C.Abstract:Following treatment with Bracken fern (Pteridium aquilinum) extract and Bracken spores a number of DNA adducts were detected by 32P-postlabeling. Three of these adducts have been described previously (Povey et al., Br. J. Cancer (1996) 74, 1342–1348) and in this study, using a slightly different protocol, four new adducts, with higher chromatographic mobility, were detected at levels ranging from 50 to 230% of those previously described. When DNA was treated in vitro with activated ptaquiloside (APT) and analysed by butanol extraction or nuclease P1 treatment, only one adduct was detected by 32P-postlabeling. This adduct was not present in the DNA from mice treated with Bracken fern or spores, suggesting either that Bracken contains genotoxins other than ptaquiloside or that the metabolism of ptaquiloside produces genotoxins not reflected by activated ptaquiloside. However, as the ATP-derived adduct has been detected previously in ileal DNA of Bracken-fed calves, species-specific differences in the metabolism of Bracken genotoxins may exist, thereby leading to differences in their biological outcomes
Mary T Fletcher - One of the best experts on this subject based on the ideXlab platform.
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residue potential of norsesquiterpene glycosides in tissues of cattle fed austral Bracken pteridium esculentum
Journal of Agricultural and Food Chemistry, 2011Co-Authors: Mary T Fletcher, Keith G Reichmann, Ian J Brock, R A Mckenzie, B J BlaneyAbstract:Austral Bracken, Pteridium esculentum, occurs widely in Australian grazing lands and contains both the known carcinogen ptaquiloside and its hydroxy analogue, ptesculentoside, with untested carcinogenic potential. Calves were fed a diet containing 19% P. esculentum that delivered 1.8 mg of ptaquiloside and 4.0 mg of ptesculentoside per kilogram of body weight (bw) per day to explore the carcass residue potential of these compounds. Concentrations of ptaquiloside and ptesculentoside in the liver, kidney, skeletal muscle, heart, and blood of these calves were determined as their respective elimination products, pterosin B and pterosin G, by HPLC-UV analysis. Plasma concentrations of up to 0.97 mu g/mL ptaquiloside and 1.30 mu g/mL ptesculentoside were found, but were shown to deplete to <10% of these values within 24 h of Bracken consumption. Both glycosides were also detected in all tissues assayed, with ptesculentoside appearing to be more residual than ptaquiloside. Up to 0.42 and 0.32 mu g/g ptesculentoside was present in skeletal muscle and liver, respectively, 15 days after Bracken consumption ended. This detection of residual glycosides in tissues of cattle feeding on Austral Bracken raises health concerns for consumers and warrants further investigation.
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ptesculentoside a novel norsesquiterpene glucoside from the australian Bracken fern pteridium esculentum
Tetrahedron Letters, 2010Co-Authors: Mary T Fletcher, P Y Hayes, Michael J Somerville, James J De VossAbstract:A novel norsesquiterpene glucoside ptesculentoside has been isolated from the Australian Bracken Pteridium esculentum, together with the known Bracken carcinogen ptaquiloside and lesser amounts of caudatoside. The structure of ptesculentoside is determined by analysis of 1D and 2D NMR spectra, and via its conversion into previously known pterosin G.