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991.
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Karthikeyan Natarajan Sylvain Leduc Paavo Pelkonen Erkki Tomppo Erik Dotzauer 《Bioenergy Research》2012,5(2):412-423
Finland considers energy production from woody biomass as an efficient energy planning strategy to increase the domestic renewable energy production in order to substitute fossil fuel consumption and reduce greenhouse gas emissions. Consequently, a number of developmental activities are implemented in the country, and one of them is the installation of second generation liquid biofuel demonstration plants. In this study, two gasification-based biomass conversion technologies, methanol and combined heat and power (CHP) production, are assessed for commercialization. Spatial information on forest resources, sawmill residues, existing biomass-based industries, energy demand regions, possible plant locations, and a transport network of Eastern Finland is fed into a geographically explicit Mixed Integer Programming model to minimize the costs of the entire supply chain which includes the biomass supply, biomass and biofuel transportation, biomass conversion, energy distribution, and emissions. The model generates a solution by determining the optimal number, locations, and technology mix of bioenergy production plants. Scenarios were created with a focus on biomass and energy demand, plant characteristics, and cost variations. The model results state that the biomass supply and high energy demand are found to have a profound influence on the potential bioenergy production plant locations. The results show that methanol can be produced in Eastern Finland under current market conditions at an average cost of 0.22??/l with heat sales (0.34??/l without heat sales). The introduction of energy policy tools, like cost for carbon, showed a significant influence on the choice of technology and CO2 emission reductions. The results revealed that the methanol technology was preferred over the CHP technology at higher carbon dioxide cost (>145??/tCO2). The results indicate that two methanol plants (360?MWbiomass) are needed to be built to meet the transport fuel demand of Eastern Finland. 相似文献
994.
Common and distinct patterns of terminal modifications to mirtrons and canonical microRNAs 总被引:1,自引:0,他引:1
Nucleotide modifications to microRNAs or their precursors can influence their processing and/or activity. A challenge to their analysis is the lack of independent references for the termini generated by primary processing; typically, these are empirically assigned as the most abundant mapped reads. Mirtrons offer such an independent measure since these microRNA hairpins are defined by splicing. Consequently, mirtron-derived reads that deviate from splice sites reflect modification following primary processing. Analysis in Drosophila revealed multiple modification patterns, including select alterations of 5' termini, many 3' resection events, and unexpectedly abundant 3' untemplated monouridylation. Resections occur on mature AGO1-loaded species, whereas uridylation occurs on pre-miRNAs but is compatible with dicing and AGO1 loading. Strikingly, we found many mirtrons whose modified reads are more abundant than those produced by primary processing. In some cases, these abundant modified reads matched the genome owing to fortuitous uridines in downstream flanking exons, thus highlighting the value of an independent reference for the primary-processed sequence. We could further extend the principle of abundant and preferred uridylation of mirtrons, relative to canonical pre-miRNAs, to Caenorhabditis elegans, mouse, and human. Finally, we found that 3' resection occurs broadly across AGO1-loaded canonical miRNA and star species. Altogether, these findings substantially broaden the complexity of terminal modification pathways acting upon small regulatory RNAs. 相似文献
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Díaz-Barrera A Soto E Altamirano C 《Journal of industrial microbiology & biotechnology》2012,39(4):613-621
Alginates are polysaccharides that are used as thickening agents, stabilizers, and emulsifiers in various industries. These
biopolymers are produced by fermentation with a limited understanding of the processes occurring at the cellular level. The
objective of this study was to evaluate the effects of agitation rate and inlet sucrose concentrations (ISC) on alginate production
and the expression of the genes encoding for alginate-lyases (algL) and the catalytic subunit of the alginate polymerase complex (alg8) in chemostat cultures of Azotobacter vinelandii ATCC 9046. Increased alginate production (2.4 g l−1) and a higher specific alginate production rate (0.1 g g−1 h−1) were obtained at an ISC of 15 g l−1. Carbon recovery of about 100% was obtained at an ISC of 10 g l−1, whereas it was close to 50% at higher ISCs, suggesting that cells growing at lower sucrose feed rates utilize the carbon
source more efficiently. In each of the steady states evaluated, an increase in algL gene expression was not related to a decrease in alginate molecular weight, whereas an increase in the molecular weight of
alginate was linked to higher alg8 gene expression, demonstrating a relationship between the alg8 gene and alginate polymerization in A. vinelandii for the first time. The results obtained provide a possible explanation for changes observed in the molecular weight of alginate
synthesized and this knowledge can be used to build a recombinant strain able to overexpress alg8 in order to produce alginates with higher molecular weights. 相似文献
998.
Climate change is occurring more rapidly in the Arctic than elsewhere, and is predicted to have a large impact on biodiversity,
since entire cold-adapted ecosystems are likely to disappear. Here, we highlight changes in the insect species richness and
community composition of wild bees, butterflies and moths over 60 years in an area situated above the tree limit (Padjelanta
National Park) in northern Sweden. Although there were changes in habitat availability, indicated by a significant decrease
in the area of a glacier (from 22 km2 in 1898 to 7.5 km2 in 2009), and an increase in the area of birch forest in the National Park, we nevertheless found relatively moderate changes
in the insect communities. Indeed, the observed number of species increased from 52 in 1944 to 64 in 2008. Remarkably, the
mean number of butterflies and moths per site, but not wild bee species, increased significantly. Among the species that were
recorded in both periods, the average altitude of 17 species had shifted downhill, 12 shifted uphill, and the altitude of
the remaining 17 had not changed. While alterations in community composition were greater at the highest altitudes, changes
in the insect community were smaller than expected, indeed much smaller than those reported from agricultural landscapes in
North-West Europe. Interestingly, our results suggest that lower alpine altitudes (600–800 m a.s.l.) have become colonized
by southern species, but also that high alpine areas (above 1,000 m a.s.l.) have recently become colonized by high alpine
species previously absent from these sites, likely as a result of increasing habitat availability. We conclude that wild bee,
butterfly, and moth communities in Arctic areas in northern Sweden are in flux, as a result of climate change and suggest
that increased attention must be given to conservation planning in cold areas. In addition, we propose that monitoring programs
should be established, because more pronounced climate-driven changes can be expected in the future. 相似文献
999.
Dana M. Blumenthal Andrew P. Norton Samuel E. Cox Erik M. Hardy Glen E. Liston Lisa Kennaway D. Terrance Booth Justin D. Derner 《Biological invasions》2012,14(2):395-404
Identifying environments where invasive plants are most invasive is key to understanding causes of invasion and developing
effective management strategies. In mixed-grass prairie, invasive plants are often successful in relatively wet, nitrogen-rich
areas, and areas protected from grazing. Dalmatian toadflax, a common invader of mixed-grass prairie, can also be favored
by high water and nitrogen availability, but is thought to be relatively unpalatable to cattle, and therefore favored by grazing.
We used spatially-adjusted model selection techniques to quantify relationships between toadflax cover (measured using very
high-resolution aerial imagery), and relative snow deposition (estimated with a blowing snow model), slope, aspect, soil texture,
and grazing intensity (estimated by proximity to water tanks). Toadflax was common throughout the 400 ha study site, occurring
in 742 of 1,861 images. Toadflax cover was high on steeper slopes, particularly those with southern aspects. These two topographic
variables were more effective in explaining toadflax distribution than modeled snow deposition, suggesting that factors other
than snow deposition cause toadflax invasion on south-facing slopes. Toadflax cover was also high in areas further from water
tanks, indicating that grazing may inhibit toadflax invasion. More broadly, this result suggests that grazing can reduce invasion
of even relatively unpalatable species in ecosystems with long evolutionary histories of grazing. 相似文献
1000.
Erik Machado-Ferreira Joseph Piesman Nordin S. Zeidner Carlos A.G. Soares 《Genetics and molecular biology》2012,35(4):862-867
As Rocky Mountain Spotted Fever is the most common tick-borne disease in South America, the presence of Rickettsia sp. in Amblyomma ticks is a possible indication of its endemicity in certain geographic regions. In the present work, bacterial DNA sequences related to Rickettsia amblyommii genes in A. dubitatum ticks, collected in the Brazilian state of Mato Grosso, were discovered. Simultaneously, Paracoccus sp. was detected in aproximately 77% of A. cajennense specimens collected in Rio de Janeiro, Brazil. This is the first report of Paracoccus sp. infection in a specific tick population, and raises the possibility of these bacteria being maintained and/or transmitted by ticks. Whether Paracoccus sp. represents another group of pathogenic Rhodobacteraceae or simply plays a role in A. cajennense physiology, is unknown. The data also demonstrate that the rickettsial 16S rRNA specific primers used forRickettsia spp. screening can also detect Paracoccus alpha-proteobacteria infection in biological samples. Hence, a PCR-RFLP strategy is presented to distinguish between these two groups of bacteria. 相似文献