364 resultados para Pteris campestris


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This paper highlights the potential benefits of smoke recovery from the production of biochar in crop management through it application as an antimicrobial agent against plant disease and as a pesticide. The study reports on the findings of zone inhibition assays on selected plant pathogens (Agrobacterium tumefacien and Xanthomonas campestris), growth studies on selected plants (Raphanus sativus and Vicia faba), and toxicity studies performed on arthropods (Myzus persicae and Tetranychus urticae). The results suggested a strong benefit to crop management in terms of crop protection against selected causal agents responsible for plant disease, with zones of inhibition observed on both Agrobacterium tumefacien and Xanthomonas campestris when inoculated with pyroligneous acid (liquid smoke) at 10% dilution. Similarly, its potential as a bio-pesticide are favorable, with a reported 20%–30% of arthropods affected (knocked out/mortality) after exposure for 48 hours.

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This article is a review of the findings of key studies into the potential benefits of pyroligneous acid, arising from charcoal production, to the agricultural industry. Through a review of bioassay studies conducted on known plant and human pathogens (e.g., Agrobacterium tumefacien and Xanthomonas campestris) and arthropods, and germination studies on selected crops, the article highlights a number of potential benefits of smoke recovery in the production of charcoal. In addition, the article calls for further research into the impact, if any, of its long-term use on environmental receptors/humans and for the development of a methodology to guarantee consistency in product composition, quality, and efficacy. In doing so, it is hoped that its widespread use as part of sustainable management practices adopted in the agricultural industry will be secured.

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This paper marks the first in a series of studies into the potential use of pyrolysis products in the development of more sustainable practices within the agricultural industry. In this study, the immediate benefits of the application of biochar to crop yields of Raphanus sativus (radishes) are assessed. Furthermore, the study reports on the preliminary findings into the potential application of pyroligneous acid (wood vinegar) as a biocidal agent against crop disease. Although germination tests undertaken on biochar/compost blends of up to 1: 2, by weight, showed no significant adverse effect from the addition of the nutrient rich carbonaceous solid, evidence of substantial increases in crop yield through the addition of biochar were not observed. In sharp contrast, zones of inhibition were observed at 3-10 vol. % upon application of pyroligneous acid to two causal agents responsible for certain diseases in vegetable and fruit crops, i.e. Rhizobium radiobacter (agrobacterium tumefaciens) and Xanthomonas campestris, highlighting the versatility in the application of pyrolysis products and avenues for exploration in the development of this biomass conversion technology.

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Glacial-interglacial fluctuations in the vegetation of South Africa might elucidate the climate system at the edge of the tropics between the Indian and Atlantic Oceans. However, vegetation records covering a full glacial cycle have only been published from the eastern South Atlantic. We present a pollen record of the marine core MD96-2048 retrieved by the Marion Dufresne from the Indian Ocean ~120 km south of the Limpopo River mouth. The sedimentation at the site is slow and continuous. The upper 6 m (spanning the past 342 Ka) have been analysed for pollen and spores at millennial resolution. The terrestrial pollen assemblages indicate that during interglacials, the vegetation of eastern South Africa and southern Mozambique largely consisted of evergreen and deciduous forests. During glacials open mountainous scrubland dominated. Montane forest with Podocarpus extended during humid periods was favoured by strong local insolation. Correlation with the sea surface temperature record of the same core indicates that the extension of mountainous scrubland primarily depends on sea surface temperatures of the Agulhas Current. Our record corroborates terrestrial evidence of the extension of open mountainous scrubland (including fynbos-like species of the high-altitude Grassland biome) for the last glacial as well as for other glacial periods of the past 300 Ka.

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O cancro é um problema de saúde crescente no mundo e é a segunda causa de morte depois das doenças cardíacas. De acordo com a Agência Internacional de Investigação em Cancro (IARC) existem atualmente mais de 10 milhões de casos de cancro por ano no mundo. Os produtos naturais oferecem oportunidades de inovação na descoberta de novos fármacos. Neste sentido, os compostos naturais isolados a partir de plantas medicinais, como potenciais fontes de novas drogas anticancerígenas, têm tido um interesse crescente. Os Óleos Essenciais (OEs) são sintetizados pelas plantas e têm sido estudados pelas suas inúmeras atividades biológicas, incluindo anticancerígena, anti-inflamatória, antimicrobiana, antiviral, antioxidante e repelente de insetos. Este estudo tem como objetivos determinar a eficácia de OEs de seis espécies de plantas das dunas de Peniche (Portugal), como potenciais agentes terapêuticos anticancerígenos em linhas celulares de cancro da mama (MCF7) e do colo-rectal (RKO), assim como perceber o mecanismo de ação destes OEs. Neste estudo, partes aéreas de Artemisia campestris subsp. maritima, Crithmum maritimum, Eryngium maritimum, Juniperus turbinata subsp. turbinata, Otanthus maritimus e Seseli tortuosum foram colhidas na praia da Consolação, em Peniche (Portugal), e os seus OEs isolados através de hidrodestilação. A composição química dos OEs foi investigada por cromatografia gasosa (GC) e por cromatografia gasosa com espetrofotometria de massa (GC-MS) e os compostos maioritários foram descritos para cada óleo. Para avaliar a atividade anticancerígena nas linhas celulares MCF7 e RKO, o método MTS (3- (4, 5-dimethyl- 2 -thiazolyl) - 2, 5-dyphenyl-2H-tetrazolium bromide) foi usado e a viabilidade celular avaliada, através de diluições sucessivas, a concentrações iniciais de 5 μL/mL e 1 μL/mL, com diluição de 1:2 e 1:10, respetivamente, comparando com o controlo (DMSO). De todos os OEs testados, a atividade anticancerígena foi descrita, em ambas as linhas celulares, como observado pela diminuição da viabilidade/proliferação celular – exceto o OE Eryngium maritimum a uma concentração inicial de 5 μL/mL.Com o objetivo de avaliar o mecanismo biológico de ação dos OEs, foi realizado um western blot para marcadores relativos ao bloqueio do ciclo celular e apoptose (p53, p21 e caspase 3 clivada), para Seseli tortuosum e Otanthus maritimus. Foi observado um aumento do nível proteína p53 nas células tratadas com estes OEs, sugerindo a indução de stress celular nas células cancerígenas testadas. No entanto, não foi observada caspase 3 clivada, sugerindo que a apoptose não terá sido a causa para a diminuição da viabilidade/proliferação celular observada. Foi ainda observado o aumento da expressão da p21 com os OEs selecionados, sugerindo que o tratamento com OE está associado ao bloqueio do ciclo celular. Para validar estas observações, a análise realizada por FACS, depois do tratamento indica um possível bloqueio do ciclo celular na fase G1. Concluindo, a concentração inicial de 5 μL/mL revelou ser muito tóxica para as linhas celulares testadas. No entanto, a uma concentração final de 1 μL/mL foi demonstrada uma diminuição da viabilidade/proliferação celular para todos os OEs. No estudo preliminar do mecanismo de ação dos OEs, foi demonstrado, face à presença da p21, que os óleos de Seseli tortuosum e Otanthus maritimus atuam bloqueando o ciclo celular. Para comprovar estes resultados, o FACS realizado (apenas no OE de Seseli tortuosum) revelou que este bloqueio pode ocorrer, pelo aumento da percentagem de células observadas, na fase G1. Estes resultados demonstram o interesse destes OEs de Peniche na procura de novos agentes quimo preventivos contra a progressão do cancro da mama e colo-rectal.

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The Gulf of Carpentaria is an epicontinental sea (maximum depth 70 m) between Australia and New Guinea, bordered to the east by Torres Strait (currently 12 m deep) and to the west by the Arafura Sill (53 m below present sea level). Throughout the Quaternary, during times of low sea-level, the Gulf was separated from the open waters of the Indian and Pacific Oceans, forming Lake Carpentaria, an isolation basin, perched above contemporaneous sea-level with outlet channels to the Arafura Sea. A preliminary interpretation is presented of the palaeoenvironments recorded in six sediment cores collected by the IMAGES program in the Gulf of Carpentaria. The longest core (approx. 15 m) spans the past 130 ka and includes a record of sea-level/lake-level changes, with particular complexity between 80 and 40 ka when sea-level repeatedly breached and withdrew from Gulf/Lake Carpentaria. Evidence from biotic remains (foraminifers, ostracods, pollen), sedimentology and geochemistry clearly identifies a final marine transgression at about 9.7 ka (radiocarbon years). Before this transgression, Lake Carpentaria was surrounded by grassland, was near full, and may have had a surface area approaching 600 km-300 km and a depth of about 15 m. The earlier rise in sea-level which accompanied the Marine Isotopic Stage 6/5 transgression at about 130 ka is constrained by sedimentological and biotic evidence and dated by optical- and thermoluminescence and amino acid racemisation methods.

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Sporomorphs and dinoflagellate cysts from site GIK16867 in the northern Angola Basin record the vegetation history of the West African forest during the last 700 ka in relation to changes in salinity and productivity of the eastern Gulf of Guinea. During most cool and cold periods, the Afromontane forest, rather than the open grass-rich dry forest, expanded to lower altitudes partly replacing the lowland rain forest of the borderlands east of the Gulf of Guinea. Except in Stage 3, when oceanic productivity was high during a period of decreased atmospheric circulation, high oceanic productivity is correlated to strong winds. The response of marine productivity in the course of a climatic cycle, however, is earlier than that of wind vigour and makes wind-stress-induced oceanic upwelling in the area less likely. Monsoon variation is well illustrated by the pollen record of increased lowland rain forest that is paired to the dinoflagellate cyst record of decreased salinity forced by increased precipitation and run-off.

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Palynological data of the marine core M 16415-2 show latitudinal shifts of the northern fringe of the tropical rain forest in north-west Africa during the last 700 ka. Savanna and dry open forest expanded southwards and tropical rain forest expanded northwards during dry and humid periods, respectively. Until 220 ka B.P., the tropical rain forest probably kept its zonal character in West Africa during glacials and interglacials. It is only during the last two glacial periods that the rain forest possibly fragmented into refugia. Throughout the Brunhes chron, pollen and spore transport was mainly by trade winds.