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991.
Macromolecular drugs hold great promise as novel therapeutics of several major disorders, such as cancer and cardiovascular
disease. However, their use is limited by lack of efficient, safe, and specific delivery strategies. Successful development
of such strategies requires interdisciplinary collaborations involving researchers with expertise on e.g., polymer chemistry,
cell biology, nano technology, systems biology, advanced imaging methods, and clinical medicine. This poses obvious challenges
to the scientific community, but also provides opportunities for the unexpected at the interface between different disciplines.
This review summarizes recent studies of macromolecular delivery that should be of interest to researchers involved in macromolecular
drug synthesis as well as in vitro and in vivo drug delivery studies. 相似文献
992.
Differential expression analysis for sequence count data 总被引:22,自引:0,他引:22
High-throughput sequencing assays such as RNA-Seq, ChIP-Seq or barcode counting provide quantitative readouts in the form
of count data. To infer differential signal in such data correctly and with good statistical power, estimation of data variability
throughout the dynamic range and a suitable error model are required. We propose a method based on the negative binomial distribution,
with variance and mean linked by local regression and present an implementation, DESeq, as an R/Bioconductor package. 相似文献
993.
An asparagine-rich protein from blood stages of Plasmodium falciparum shares determinants with sporozoites. 总被引:10,自引:1,他引:10 下载免费PDF全文
H D Stahl A E Bianco P E Crewther T Burkot R L Coppel G V Brown R F Anders D J Kemp 《Nucleic acids research》1986,14(7):3089-3102
We describe a cDNA clone derived from mRNA of asexual blood-stages of the malaria parasite Plasmodium falciparum. This clone, designated Ag319, expresses a P.falciparum antigen fused to beta-galactosidase in Escherichia coli. Human antibodies from Papua New Guinea were affinity-purified by adsorption to extracts of Ag319 immobilized on CNBr-Sepharose. The antibodies reacted predominantly with P. falciparum polypeptides of Mr 220,000 and 160,000, and a number of ill-defined lower molecular weight species. Antibodies reacted in indirect immunofluorescence with all asexual blood-stages although the antigen appeared to be most abundance in the schizont. Surprizingly the antibodies also reacted with sporozoites. The amino acid sequence predicted from the complete nucleotide sequence of this clone is remarkable because 40% of the residues are Asn, and so the antigen has been termed the Asparagine-Rich Protein (ARP). Like other P. falciparum antigens, ARP contains tandemly repetitive sequences, based on the tetrapeptide Asn-Asn-Asn-Met and we have confirmed that these represent natural epitopes by reaction of the corresponding synthetic peptides with human antibodies. Surprisingly, ARP is also rich in Asn outside the tandem repeats. 相似文献
994.
The red king crab (Paralithodes camtschaticus) was introduced in the Barents Sea in the 1960s and soon established a viable population. Proper management and exploitation
of the Barents Sea king crab stock require better understanding of the spatial dynamics at different scales. This study examines
the small-scale movement patterns of seven adult male crabs tracked for a period of up to one month from mid July to mid August
at 150 m depth in a semi-enclosed fjord on the Russo-Norwegian border. The crabs were tagged with acoustic transmitters and
their movements monitored with an acoustic positioning system. Low walking speeds (<0.01 m s−1) were most frequent but the crabs could move at a maximum speed of 0.15 m s−1 and walk an actual distance of up to 270 m over a period of one hour. However, the crabs usually moved within a relatively
restricted area with mean hourly longest rectilinear distance varying from 26 to 64 m. The crabs alternated between periods
of low and high activity, which could reflect feeding in and movements between food patches. The lack of a diel activity rhythm
may be due to high light levels during the polar summer night, or a chemically mediated food search strategy. 相似文献
995.
Assiminea affinis (Mousson ms) Böttger, 1887(=A. queenslandica [Pilsbry ms] Thiele, 1927), a previously unrecognised Australian assimineid species, is described anatomically and allocated to the genus Taiwanassiminea Kuroda and Habe, 1950, first described from Taiwan. This is the first record of the genus from Australia. Taiwanassiminea affinis is found in slightly brackish waters in the upper tidal reaches of the larger rivers from northern Queensland to the Shoalhaven River in the southern half of New South Wales. The terrestrial Cyclotropis Tapparone-Canefri, 1883, which has somewhat similar shell and radular characters, is redefined and several species (Assiminea bedaliensis Rensch, 1934; Paludinella javana Thiele, 1927; Assiminea lentula, A. riparia and A. sororcula, all Benthem Jutting, 1963) previously included in Cyclotropis are transferred to Taiwanassiminea. 相似文献
996.
Climate change‐induced vegetation change as a driver of increased subarctic biogenic volatile organic compound emissions 下载免费PDF全文
Hanna Valolahti Minna Kivimäenpää Patrick Faubert Anders Michelsen Riikka Rinnan 《Global Change Biology》2015,21(9):3478-3488
Emissions of biogenic volatile organic compounds (BVOCs) have been earlier shown to be highly temperature sensitive in subarctic ecosystems. As these ecosystems experience rapidly advancing pronounced climate warming, we aimed to investigate how warming affects the BVOC emissions in the long term (up to 13 treatment years). We also aimed to assess whether the increased litterfall resulting from the vegetation changes in the warming subarctic would affect the emissions. The study was conducted in a field experiment with factorial open‐top chamber warming and annual litter addition treatments on subarctic heath in Abisko, northern Sweden. After 11 and 13 treatment years, BVOCs were sampled from plant communities in the experimental plots using a push–pull enclosure technique and collection into adsorbent cartridges during the growing season and analyzed with gas chromatography–mass spectrometry. Plant species coverage in the plots was analyzed by the point intercept method. Warming by 2 °C caused a 2‐fold increase in monoterpene and 5‐fold increase in sesquiterpene emissions, averaged over all measurements. When the momentary effect of temperature was diminished by standardization of emissions to a fixed temperature, warming still had a significant effect suggesting that emissions were also indirectly increased. This indirect increase appeared to result from increased plant coverage and changes in vegetation composition. The litter addition treatment also caused significant increases in the emission rates of some BVOC groups, especially when combined with warming. The combined treatment had both the largest vegetation changes and the highest BVOC emissions. The increased emissions under litter addition were probably a result of a changed vegetation composition due to alleviated nutrient limitation and stimulated microbial production of BVOCs. We suggest that the changes in the subarctic vegetation composition induced by climate warming will be the major factor indirectly affecting the BVOC emission potentials and composition. 相似文献
997.
Multiple stressors on biotic interactions: how climate change and alien species interact to affect pollination 总被引:1,自引:0,他引:1
Oliver Schweiger Jacobus C. Biesmeijer Riccardo Bommarco Thomas Hickler Philip E. Hulme Stefan Klotz Ingolf Kühn Mari Moora Anders Nielsen Ralf Ohlemüller Theodora Petanidou Simon G. Potts Petr Pyšek Jane C. Stout Martin T. Sykes Thomas Tscheulin Montserrat Vilà Gian‐Reto Walther Catrin Westphal Marten Winter Martin Zobel Josef Settele 《Biological reviews of the Cambridge Philosophical Society》2010,85(4):777-795
Global change may substantially affect biodiversity and ecosystem functioning but little is known about its effects on essential biotic interactions. Since different environmental drivers rarely act in isolation it is important to consider interactive effects. Here, we focus on how two key drivers of anthropogenic environmental change, climate change and the introduction of alien species, affect plant–pollinator interactions. Based on a literature survey we identify climatically sensitive aspects of species interactions, assess potential effects of climate change on these mechanisms, and derive hypotheses that may form the basis of future research. We find that both climate change and alien species will ultimately lead to the creation of novel communities. In these communities certain interactions may no longer occur while there will also be potential for the emergence of new relationships. Alien species can both partly compensate for the often negative effects of climate change but also amplify them in some cases. Since potential positive effects are often restricted to generalist interactions among species, climate change and alien species in combination can result in significant threats to more specialist interactions involving native species. 相似文献
998.
Prokaryotic toxin-antitoxin stress response loci 总被引:11,自引:0,他引:11
Although toxin-antitoxin gene cassettes were first found in plasmids, recent database mining has shown that these loci are abundant in free-living prokaryotes, including many pathogenic bacteria. For example, Mycobacterium tuberculosis has 38 chromosomal toxin-antitoxin loci, including 3 relBE and 9 mazEF loci. RelE and MazF are toxins that cleave mRNA in response to nutritional stress. RelE cleaves mRNAs that are positioned at the ribosomal A-site, between the second and third nucleotides of the A-site codon. It has been proposed that toxin-antitoxin loci function in bacterial programmed cell death, but evidence now indicates that these loci provide a control mechanism that helps free-living prokaryotes cope with nutritional stress. 相似文献
999.
Distribution and diversity of palms in a tropical biodiversity hotspot (Thailand) assessed by species distribution modeling 下载免费PDF全文
Jantrararuk Tovaranonte Anne Blach‐Overgaard Ratchada Pongsattayapipat Jens‐Christian Svenning Anders S. Barfod 《Nordic Journal of Botany》2015,33(2):214-224
Species distribution modeling has been widely used to address questions related to ecology, biogeography and species conservation on global and regional scales. Here, we study palms (Arecaceae) in a tropical biodiversity hotspot (Thailand) using species distribution modeling to assess range‐limiting factors and estimate distribution and diversity patterns based on a comprehensive compilation of occurrence records. We focused on palms as a model group due to their key‐stone importance for ecosystem functioning and socio‐economics. Different combinations of climatic, non‐climatic environmental and spatial predictors were used. The most accurate models as indicated by the ‘area under the receiver operating characteristic curve’ (AUC) statistic were those that combined all predictors. The four strongest single predictors of palm species distributions were, in decreasing order of importance, 1) latitude, 2) precipitation of driest quarter, 3) annual precipitation, and 4) minimum temperature of the coldest month, suggesting rainfall patterns and latitudinal spatial constraints as the main range determinants. Overlaying the predicted distributions revealed that potential palm hotspots are situated in the provinces of Satun and Yala in southern Thailand where vast areas remain relatively open to the discovery of new palm records and perhaps even new species. 相似文献
1000.
Jinshu Chi Mats B. Nilsson Hjalmar Laudon Anders Lindroth Jrgen Wallerman Johan E. S. Fransson Natascha Kljun Tomas Lundmark Mikaell Ottosson Lfvenius Matthias Peichl 《Global Change Biology》2020,26(4):2353-2367
The boreal biome exchanges large amounts of carbon (C) and greenhouse gases (GHGs) with the atmosphere and thus significantly affects the global climate. A managed boreal landscape consists of various sinks and sources of carbon dioxide (CO2), methane (CH4), and dissolved organic and inorganic carbon (DOC and DIC) across forests, mires, lakes, and streams. Due to the spatial heterogeneity, large uncertainties exist regarding the net landscape carbon balance (NLCB). In this study, we compiled terrestrial and aquatic fluxes of CO2, CH4, DOC, DIC, and harvested C obtained from tall‐tower eddy covariance measurements, stream monitoring, and remote sensing of biomass stocks for an entire boreal catchment (~68 km2) in Sweden to estimate the NLCB across the land–water–atmosphere continuum. Our results showed that this managed boreal forest landscape was a net C sink (NLCB = 39 g C m?2 year?1) with the landscape–atmosphere CO2 exchange being the dominant component, followed by the C export via harvest and streams. Accounting for the global warming potential of CH4, the landscape was a GHG sink of 237 g CO2‐eq m?2 year?1, thus providing a climate‐cooling effect. The CH4 flux contribution to the annual GHG budget increased from 0.6% during spring to 3.2% during winter. The aquatic C loss was most significant during spring contributing 8% to the annual NLCB. We further found that abiotic controls (e.g., air temperature and incoming radiation) regulated the temporal variability of the NLCB whereas land cover types (e.g., mire vs. forest) and management practices (e.g., clear‐cutting) determined their spatial variability. Our study advocates the need for integrating terrestrial and aquatic fluxes at the landscape scale based on tall‐tower eddy covariance measurements combined with biomass stock and stream monitoring to develop a holistic understanding of the NLCB of managed boreal forest landscapes and to better evaluate their potential for mitigating climate change. 相似文献