| 1. |
- Alalam, Hanna, et al.
(författare)
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A High-Throughput Method for Screening for Genes Controlling Bacterial Conjugation of Antibiotic Resistance.
- 2020
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Ingår i: mSystems. - 2379-5077. ; 5:6
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Tidskriftsartikel (refereegranskat)abstract
- The rapid horizontal transmission of antibiotic resistance genes on conjugative plasmids between bacterial host cells is a major cause of the accelerating antibiotic resistance crisis. There are currently no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation, which prevents understanding and targeting conjugation. We introduce a novel experimental framework to screen for conjugation-based horizontal transmission of antibiotic resistance between >60,000 pairs of cell populations in parallel. Plasmid-carrying donor strains are constructed in high-throughput. We then mix the resistance plasmid-carrying donors with recipients in a design where only transconjugants can reproduce, measure growth in dense intervals, and extract transmission times as the growth lag. As proof-of-principle, we exhaustively explore chromosomal genes controlling F-plasmid donation within Escherichia coli populations, by screening the Keio deletion collection in high replication. We recover all seven known chromosomal gene mutants affecting conjugation as donors and identify many novel mutants, all of which diminish antibiotic resistance transmission. We validate nine of the novel genes' effects in liquid mating assays and complement one of the novel genes' effect on conjugation (rseA). The new framework holds great potential for exhaustive disclosing of candidate targets for helper drugs that delay resistance development in patients and societies and improve the longevity of current and future antibiotics. Further, the platform can easily be adapted to explore interspecies conjugation, plasmid-borne factors, and experimental evolution and be used for rapid construction of strains.IMPORTANCE The rapid transmission of antibiotic resistance genes on conjugative plasmids between bacterial host cells is a major cause of the accelerating antibiotic resistance crisis. There are currently no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation, which prevents understanding and targeting conjugation. We introduce a novel experimental framework to screen for conjugation-based horizontal transmission of antibiotic resistance between >60,000 pairs of cell populations in parallel. As proof-of-principle, we exhaustively explore chromosomal genes controlling F-plasmid donation within E. coli populations. We recover all previously known and many novel chromosomal gene mutants that affect conjugation efficiency. The new framework holds great potential for rapid screening of compounds that decrease transmission. Further, the platform can easily be adapted to explore interspecies conjugation, plasmid-borne factors, and experimental evolution and be used for rapid construction of strains.
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| 2. |
- Alalam, Hanna, et al.
(författare)
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Conjugation factors controlling F-plasmid antibiotic resistance transmission
- 2018
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Ingår i: BioRxiv. - : Cold Spring Harbor Laboratory.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The rapid horizontal transmission of many antibiotic resistance genes between bacterial host cells on conjugative plasmids is a major cause of the accelerating antibiotic resistance crisis. Preventing understanding and targeting conjugation, there currently are no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation. We introduce a novel experimental framework to screen for conjugation based horizontal transmission of antibiotic resistance between >60,000 pairs of cell populations in parallel. Plasmid-carrying donor strains are constructed in high throughput. We then mix the resistance plasmid carrying donors with recipients in a design where only transconjugants can reproduce, measure growth in dense intervals and extract transmission times as the growth lag. As proof-of-principle, we exhaustively explored chromosomal genes controlling F plasmid donation within E. coli populations, by screening the Keio deletion collection at high replication. We recover all six known chromosomal gene mutants affecting conjugation and identify >50 novel factors, all of which diminish antibiotic resistance transmission. We verify 10 of the novel genes' effects in a liquid mating assay. The new framework holds great potential for exhaustive disclosing of candidate targets for helper drugs that delay resistance development in patients and societies and improves the longevity of current and future antibiotics.
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| 3. |
- Berndes, Göran, 1966, et al.
(författare)
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Multifunctional biomass production systems - an overview with presentation of specific applications in India and Sweden
- 2008
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Ingår i: Biofuels, Bioproducts and Biorefining. - : Wiley. - 1932-104X .- 1932-1031. ; 2:1, s. 16-25
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Tidskriftsartikel (refereegranskat)abstract
- This perspective discusses multi-functional biomass production systems, which are located, designed, integrated and managed so as to provide specific environmental services, in addition to biomass supply. Besides discussing the general concept and outlining a range of different possible applications, we present in somewhat more detail specific applications of such systems for the cases of Sweden and India. The overall conclusion is that the environmental benefits from a large-scale establishment of multi-functional biomass production systems could be substantial. Given that suitable mechanisms to put a premium on the provided environmental services can be identified and implemented, additional revenues can be linked to biomass production systems and this could enhance the socioeconomic attractiveness and significantly improve the competitiveness of the produced biomass on the market. The provision of additional environmental services also contributes to local sustainable development, which is in many cases a prerequisite for local support for the production systems.
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| 4. |
- Davis, Marion, et al.
(författare)
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Sharing the Land: Restoring Degraded Ecosystems and Improving Livelihoods Through Agroforestry
- 2014
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Ingår i: Stockholm Environment Institute: Swedish International Agricultural Network Initiative (SIANI) and Forest, Climate & Livelihood Research Network (Focali), “Forests, Landscapes and Food Security” theme brief. ; , s. 4-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The challenge is daunting: how to feed more than 7 billionpeople – nearly 10 billion by 20501 – even as key resourcesbecome scarcer. Roughly 24% of the world’s land area is degrading,including more than a fifth of the cropland and nearly a third of the forests – yet 1.5 billion people directly depend on degraded areas. Some countries are particularly hard-hit:95% of Swaziland’s land is degraded, as is 66% of Angola’s, 64% of Gabon’s, 60% of Thailand’s, and 60% of Zambia’s. In China, 457 million people are affected by land degradation.
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| 5. |
- Davis, Marion, et al.
(författare)
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Trees in home gardens: Making the most of an age-old practice to improve food security and nutrition.
- 2014
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Ingår i: Stockholm Environment Institute: Swedish International Agricultural Network Initiative (SIANI) and Forest, Climate & Livelihood Research Network (Focali), “Forests, Landscapes and Food Security” theme brief.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Home gardens have been vital to human societies for thousands of years: from clusters of beneficial trees and shrubs planted on forest edges in pre-historic times, to the lush ediblegardens grown traditionally in many tropical regions, to the tiny, densely planted backyards that dot cities worldwide.
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| 6. |
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| 7. |
- Engström, Linda, et al.
(författare)
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Producing Feedstock for Biofuels : Land-Use and Local Environmental Impacts
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Feedstock production and conversion to biofuels can affect the local environment in many different ways. Given that biofuels presently mostly are produced from conventional food crops, impacts resemble those characterising the present day agriculture. These depend on the crops produced, the production systems employed, governance conditions, and local environmental conditions. In the main report, production system characteristics and current documented environmental impacts related to e.g. air and water quality and biodiversity – associated with the production of relevant biofuel crops are presented in each country land-use profile
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| 9. |
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| 10. |
- Jepsen, Martin Rudbeck, et al.
(författare)
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What Awaits Myanmar's Uplands Farmers? Lessons Learned from Mainland Southeast Asia
- 2019
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Ingår i: Land. - : MDPI AG. - 2073-445X. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Mainland Southeast Asia (MSA) has seen sweeping upland land use changes in the past decades, with transition from primarily subsistence shifting cultivation to annual commodity cropping. This transition holds implications for local upland communities and ecosystems. Due to its particular political regime, Myanmar is at the tail of this development. However, with Myanmar's official strategy of agricultural commercialization and intensification, recent liberalization of the national economy, and influx of multinational agricultural companies, the effects on upland land transitions could come fast. We analyze the current state of upland land use in Myanmar in a socio-economic and political context, identify the dynamics in three indicator commodity crops (maize, cassava, and rubber), and discuss the state driven economic, tenurial and policy reforms that have occurred in upland areas of mainland Southeast Asian countries in past decades. We draw on these insights to contextualize our study and hypothesize about possible transition pathways for Myanmar. The transition to annual commodity cropping is generally driven by a range of socio-economic and technical factors. We find that land use dynamics for the three indicator crops are associated with market demand and thus the opening of national Southeast-Asian economies, research and development of locally suitable high yielding varieties (HYVs), and subsidies for the promotion of seeds and inputs. In contrast, promotion of HYVs in marginal areas and without adequate agricultural extension services may results in agricultural contraction and yield dis-intensification. The environmental impacts of the transition depend on the transition pathway, e.g., through large-scale plantation projects or smallholder initiatives. The agricultural development in upland MSA follows a clear diffusion pattern with transition occurring first in Thailand, spreading to Vietnam, Cambodia and Laos. While these countries point to prospects for Myanmar, we hypothesize that changes will come slow due to Myanmar's sparse rural infrastructure, with uncertainty about tenure, in particular in areas still troubled by armed conflicts, and unwillingness of international investors to approach Myanmar given the recent setbacks to the democratization process.
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