299 research outputs found
Spatial variability of soil properties and soil erodibility in the Alqueva reservoir watershed
The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor) were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this end, three areas representative of different land uses (agroforestry grassland, lucerne crop and olive orchard) were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation), vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while the K factor increased with intensive cultivation. The HJ-Biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. The K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion
IMPORTANCE OF RESERVOIRS FOR WATERBIRDS IN SEMI‐ARID BRAZIL
ABSTRACT ∙ To investigate the value of water reservoirs for waterbirds in semi‐arid lands, we studied the waterbird community in semi‐arid of Paraíba, Brazil, and compared the results with other assemblages both in semi‐arid and humid regions of Neotropics. Birds were counted during 15 months in 12 reservoirs belonging to the Piranhas‐Açu River basin. We counted 4111 waterbirds and recorded 36 species. The most abundant species, such as Wattled Jacana (Jacana jacana) and Common Gallinule (Gallinula galeata), were strongly tied to aquatic vegetation. All species have wide distribution, far beyond the borders of the semi‐arid region. Abundance and richness of waterbirds in Paraíba are lower than in more humid regions of Neotropics. Species composition in all semi‐arid sites studied seems to be a reduced version of assemblages in surrounding humid regions. Nevertheless, reservoirs may become important alternatives as feeding and breeding sites where the natural environments are insufficient to sustain waterbird populations. RESUMO ∙ A importância dos açudes para as aves aquáticas no semiárido brasileiro Para investigar a importância de açudes para aves aquáticas em regiões semiáridas, estudamos a comunidade de aves no semiárido da Paraíba, Brasil, e comparamos os resultados com outras assembleias em regiões semiáridas e úmidas dos neotrópicos. Durante 15 meses foram realizados censos da avifauna em 12 açudes na bacia do rio Piranhas‐Açu. Foram registradas 4111 aves e 36 espécies. As espécies mais abundantes, como a Jaçanã (Jacana jacana) e a Galinha‐d’água (Gallinula galeata), foram associadas às macrófitas. Todas as espécies possuem vasta distribuição geográfica, ultrapassando as fronteiras da região semiárida. A abundância e a riqueza foram menores que aquelas encontradas em regiões úmidas. A composição de espécies nas regiões semiáridas estudadas compreende uma versão reduzida das assembleias das regiões úmidas. Todavia, os açudes podem se tornar alternativas importantes como locais de alimentação e reprodução onde os ambientes naturais são insuficientes para manter as populações de aves
A modular cloning toolkit for genome editing in plants
Background
CRISPR/Cas has recently become a widely used genome editing tool in various organisms, including plants. Applying CRISPR/Cas often requires delivering multiple expression units into plant and hence there is a need for a quick and easy cloning procedure. The modular cloning (MoClo), based on the Golden Gate (GG) method, has enabled development of cloning systems with standardised genetic parts, e.g. promoters, coding sequences or terminators, that can be easily interchanged and assembled into expression units, which in their own turn can be further assembled into higher order multigene constructs.
Results
Here we present an expanded cloning toolkit that contains 103 modules encoding a variety of CRISPR/Cas-based nucleases and their corresponding guide RNA backbones. Among other components, the toolkit includes a number of promoters that
allow expression of CRISPR/Cas nucleases (or any other coding sequences) and their guide RNAs in monocots and dicots. As part of the toolkit, we present a set of modules that enable quick and facile assembly of tRNA-sgRNA polycistronic units without a PCR step involved. We also demonstrate that our tRNA-sgRNA system is functional in wheat protoplasts.
Conclusions
We believe the presented CRISPR/Cas toolkit is a great resource that will contribute towards wider adoption of the CRISPR/Cas genome editing technology and modular cloning by researchers across the plant science community
Inverse box-counting method: A fractal-based procedure to create biospheric landscape patterns
1st WSEAS International Conference on Landscape Architecture (LA 2008), Univ Algarve, Algarve, PORTUGAL, JUN 11-13, 2008International audiencePlanners and designers are interested in replicating biospheric landscape patterns to reclaim surface mines to match existing natural landscape patterns. One approach that shows promise is the use of fractal geometry to generate biospheric landscape patterns. While the measurement of the actual fractal dimension of a landscape can be difficult, a box-counting method was developed at INHP, Angers, France which approximates the spatial patterns of biospheric landscapes. Essentially the procedure entails covering a natural object/pattern with a regular grid of size r and then one simply counts the number of grid boxes, N(r), that contain some part of the object. The boxes are subdivided and the value of r is progressively reduced and N(r) is similarly re-measured until some of the boxes become empty (containing no landscape objects of interest). Then the fractal dimension of the object is approximated to be the log(N(r))/Iog(l/r). We illustrate this procedure by measuring and replicating a stand of trees in the Upper Peninsula of Michigan. Our study revealed a fractal number of 1.0 17 (p < 0.01), with a mean of 77.4 trees per 100 in by 100 in stand, and a standard deviation of 34.87 trees per stand
The Influence of Affect in Help-Seeking Behaviors and Performance in an Intelligent Tutoring System
Help is a typical feature in ITSs
The decision to seek help is influenced by metacognitive, affective, and social competencies
Efficient CRISPR/Cas-Mediated Targeted Mutagenesis in Spring and Winter Wheat Varieties
CRISPR/Cas technology has recently become the molecular tool of choice for gene function studies in plants as well as crop improvement. Wheat is a globally important staple crop with a well annotated genome and there is plenty of scope for improving its agriculturally important traits using genome editing technologies, such as CRISPR/Cas. As part of this study we targeted three different genes in hexaploid wheat Triticum aestivum: TaBAK1-2 in the spring cultivar Cadenza as well as Ta-eIF4E and Ta-eIF(iso)4E in winter cultivars Cezanne, Goncourt and Prevert. Primary transgenic lines carrying CRISPR/Cas-induced indels were successfully generated for all targeted genes. While BAK1 is an important regulator of plant immunity and development, Ta-eIF4E and Ta-eIF(iso)4E act as susceptibility (S) factors required for plant viruses from the Potyviridae family to complete their life cycle. We anticipate the resultant homozygous tabak1-2 mutant lines will facilitate studies on the involvement of BAK1 in immune responses in wheat, while ta-eif4e and ta-eif(iso)4e mutant lines have the potential to become a source of resistance to wheat spindle streak mosaic virus (WSSMV) and wheat yellow mosaic virus (WYMV), both of which are important pathogens of wheat. As winter wheat varieties are generally less amenable to genetic transformation, the successful experimental methodology for transformation and genome editing in winter wheat presented in this study will be of interest to the research community working with this crop
What is required to end the AIDS epidemic as a public health threat by 2030? The cost and impact of the fast-track approach
In 2011 a new Investment Framework was proposed that described how the scale-up of key HIV interventions could dramatically reduce new HIV infections and AIDS-related deaths in low and middle income countries by 2015. This framework included ambitious coverage goals for prevention and treatment services for 2015, resulting in a reduction of new HIV infections by more than half, in line with the goals of the declaration of the UN High Level Meeting in June 2011. However, the approach suggested a leveling in the number of new infections at about 1 million annually-far from the UNAIDS goal of ending AIDS by 2030. In response, UNAIDS has developed the Fast-Track approach that is intended to provide a roadmap to the actions required to achieve this goal. The Fast-Track approach is predicated on a rapid scale-up of focused, effective prevention and treatment services over the next 5 years and then maintaining a high level of programme implementation until 2030. Fast-Track aims to reduce new infections and AIDS-related deaths by 90% from 2010 to 2030 and proposes a set of biomedical, behavioral and enabling intervention targets for 2020 and 2030 to achieve that goal, including the rapid scale-up initiative for antiretroviral treatment known as 90-90-90. Compared to a counterfactual scenario of constant coverage for all services at early-2015 levels, the Fast-Track approach would avert 18 million HIV infections and 11 million deaths from 2016 to 2030 globally. This paper describes the analysis that produced these targets and the estimated resources needed to achieve them in low- and middle-income countries. It indicates that it is possible to achieve these goals with a significant push to achieve rapid scale-up of key interventions between now and 2020. The annual resources required from all sources would rise to US8.2Bn in lower middle-income countries and US$10.5Bn in upper-middle-income-countries by 2020 before declining approximately 9% by 2030
Influência do teor de matéria seca e do inoculante bacteriano nas características físicas e químicas da silagem de capim Tanzânia.
Foram avaliados os efeitos do teor de matéria seca c da adição de inoculantes bacteriano sobre a composição químico-bromatológica e perdas em silagens do capim Tanzânia. O uso do inoculante não foi efetivo em preservar a PB. Os índices de recuperação de matéria seca e as perdas de MS, na forma de efluente e gases, foram respectivamente de 90,6%; 53,7 kg (I MV e 6,4% da MS nas silagcns não-emurchecidas, 93,6%; 16,8 kg ri MV e 5,0% com adição de milheto grão e 92,2%; 3,6 kg (I MVe 6,2% naquelas emurchecidas. As densidades de massa verde/matéria seca foram 346/105,455/145 c 442/97 kg m-3 nas silagens emurchecidas, adicionadas com milheto e com umidade original, respectivamente. Como a elevação no teor de MS não alterou o índice de recuperação de MS, apesar de promover algumas modificações na composição química das silagens, a opção pelos tratamentos vai depender da ponderação de fatores que facilitem a operacionalidadc e reduzam os custos na confecção da silagem
Efeito da adição da torta de dendê no perfil fermentativo da silagem do resíduo da extração do palmito da pupunha (Bactris gasipaes Kunth).
Resumo: A extração de palmito da pupunha, na região Sul do estado da Bahia, vem gerando grande quantidade de derivados, que podem ser uma alternativa de alimentação para os ruminantes na forma de ensilagem. Podendo, assim, solucionar o destino desses co-produtos e, desta forma, gerar tecnologias voltadas para o uso sustentável dos recursos naturais associados ao ecossistema regional. O objetivo do trabalho foi avaliar o perfil fermentativo das silagens do coproduto agroindustrial da extração do palmito da pupunha in natura, aditivada com torta de dendê (10% do peso verde) e emurchecida. Utilizou-se silos de PVC com 10 cm de diâmetros x 40 cm de comprimento. As aberturas dos silos ocorreram aos 1, 3, 5, 7, 14, 28 e 56 dias após a ensilagem. Os valores de pH não apresentaram diferença significativa (P>0,05) entre os tratamentos tendo como média (3,82) no dia 56, no entanto esses valores apresentaram padrão de mudança cúbica ao longo dos dias com o valor mínimo sendo atingido no dia 14 para todos os tratamentos. A adição da torta de dendê na silagem elevou os teores de MS (21,06%) e PB (7,79%), reduziu os valores de N-NH3/NT (3,73%) e de perda de MS (0,82%) apresentando diferença significativa (P0.05) between the treatments (3.82) in 56 day, however these with the minimum value being reached in the 14 day for all treatments. The addition of palm meal improve dry matter values (21.06%) and crude protein (7.79%), reduced the values of ammoniac nitrogen (N-NH3/NT, 3.73%) and dry matter losses (0.82%) presenting significant difference (P<0.05) for all treatments. The addition of palm meal in pupunha by-product silage improved the fermentation parameters, increased crude protein. This practice is able to be an alternative for feeding ruminants
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