共查询到20条相似文献,搜索用时 578 毫秒
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Michael F. Brown 《American anthropologist》1998,100(3):840-841
Guía Etnográfica de la Alta Amazonía, vol. (Mai Huna, Yagua, Ticuna). Fernando Santos and Frederica Barclay. eds. Quito: Facultad Latinamericana de Ciencias Sociales (FLACSO) and Instituto Frances de Estudios Andinos (IFEA), 1994.456 pp. 相似文献
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Matthias Hackl Stefan Brunner Klaus Fortschegger Carina Schreiner Lucia Micutkova Christoph Mück Gerhard T. Laschober Günter Lepperdinger Natalie Sampson Peter Berger Dietmar Herndler‐Brandstetter Matthias Wieser Harald Kühnel Alois Strasser Mark Rinnerthaler Michael Breitenbach Michael Mildner Leopold Eckhart Erwin Tschachler Andrea Trost Johann W. Bauer Christine Papak Zlatko Trajanoski Marcel Scheideler Regina Grillari‐Voglauer Beatrix Grubeck‐Loebenstein Pidder Jansen‐Dürr Johannes Grillari 《Aging cell》2010,9(2):291-296
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Abstract Aim The research explores how changes in disturbance regime resulting from human settlement may affect landscape structure. A spatially explicit grid‐based simulation model is used to explore the interplay between humans, fire regime and landscape composition. Location The study site for this research is the botanical reserve at Mont Do, New Caledonia. The endemic conifer Araucaria laubenfelsii (Araucariaceae) forms a key component of the landscape at Mont Do. This species is unusual in that it is found scattered as an emergent in maquis and as a canopy species in adjacent rain forest patches. Although now dominated by a low maquis, prior to human settlement of New Caledonia, montane landscapes such as Mont Do are likely to have been heavily forested. Methods A spatially explicit simulation model, based on field data and palaeoecological information, was used to explore interactions between disturbance regime and the landscape. The model is described briefly here and more fully in Perry & Enright (2002) Ecological Modelling, 152 , 279. Results The model suggests that human‐influenced changes to the fire regime at Mont Do have been important in generating the current landscape structure. The origin and maintenance of forest landscapes and maquis‐forest mosaic landscapes are considered in the context of alternative stable states. Strong feedback loops between fire size and landscape composition, mediated at the smaller scale by other similar mechanisms, are capable of driving landscape change. The utility of a spatial state and transition modelling approach is demonstrated. Main conclusions The current landscape pattern on Mont Do is likely the result of changes to the fire regime occurring since human settlement. The specific mechanisms for this change outlined here may occur in a number of other similar systems. Understanding the origin and persistence of these ‘fire landscapes’ in New Caledonia and in the south‐west Pacific in general is crucial for their effective management. 相似文献
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Ustilaginoidea virens, which causes rice false smut (RFS), is one of the
most detrimental rice fungal diseases and poses a severe threat to rice production
and quality. Effectors in U. virens often act as a group of essential virulence factors that play crucial roles in the interaction between host and the pathogen. Thus,
the functions of individual effectors in U. virens need to be further explored. Here,
we found a small secreted hypersensitive response-inducing protein
UVI_02019870 was highly conserved in fungi. Furthermore, we performed
Y2H and BiFC assay to demonstrated UVI_02019870 interacted with OsCPL1,
which was predicted as a chloroplast precursor to regulate chloroplast signaling
pathways. Our data provide a theory for gaining an insight into the molecular
mechanisms underlying the UVI_02019870 virulence function. 相似文献
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Elevated CO<Subscript>2</Subscript>, litter chemistry,and decomposition: a synthesis 总被引:10,自引:0,他引:10
Richard J. Norby M. Francesca Cotrufo Philip Ineson Elizabeth G. O’Neill Josep G. Canadell 《Oecologia》2001,127(2):153-165
The results of published and unpublished experiments investigating the impacts of elevated [CO2] on the chemistry of leaf litter and decomposition of plant tissues are summarized. The data do not support the hypothesis that changes in leaf litter chemistry often associated with growing plants under elevated [CO2] have an impact on decomposition processes. A meta-analysis of data from naturally senesced leaves in field experiments showed that the nitrogen (N) concentration in leaf litter was 7.1% lower in elevated [CO2] compared to that in ambient [CO2]. This statistically significant difference was: (1) usually not significant in individual experiments, (2) much less than that often observed in green leaves, and (3) less in leaves with an N concentration indicative of complete N resorption. Under ideal conditions, the efficiency with which N is resorbed during leaf senescence was found not to be altered by CO2 enrichment, but other environmental influences on resorption inevitably increase the variability in litter N concentration. Nevertheless, the small but consistent decline in leaf litter N concentration in many experiments, coupled with a 6.5% increase in lignin concentration, would be predicted to result in a slower decomposition rate in CO2-enriched litter. However, across the assembled data base, neither mass loss nor respiration rates from litter produced in elevated [CO2] showed any consistent pattern or differences from litter grown in ambient [CO2]. The effects of [CO2] on litter chemistry or decomposition were usually smallest under experimental conditions similar to natural field conditions, including open-field exposure, plants free-rooted in the ground, and complete senescence. It is concluded that any changes in decomposition rates resulting from exposure of plants to elevated [CO2] are small when compared to other potential impacts of elevated [CO2] on carbon and N cycling. Reasons for experimental differences are considered, and recommendations for the design and execution of decomposition experiments using materials from CO2-enrichment experiments are outlined. 相似文献
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Minoru Sasaki Masatoshi Kondo Kohji Sato Mai Umeda Keigo Kawabata Yoshito Takahashi Tamio Suzuki Kayoko Matsunaga Shintaro Inoue 《Pigment cell & melanoma research》2014,27(5):754-763
Rhododendrol, an inhibitor of melanin synthesis developed for lightening/whitening cosmetics, was recently reported to induce a depigmentary disorder principally at the sites of repeated chemical contact. Rhododendrol competitively inhibited mushroom tyrosinase and served as a good substrate, while it also showed cytotoxicity against cultured human melanocytes at high concentrations sufficient for inhibiting tyrosinase. The cytotoxicity was abolished by phenylthiourea, a chelator of the copper ions at the active site, and by specific knockdown of tyrosinase with siRNA. Hence, the cytotoxicity appeared to be triggered by the enzymatic conversion of rhododendrol to active product(s). No reactive oxygen species were detected in the treated melanocytes, but up‐regulation of the CCAAT‐enhancer‐binding protein homologous protein gene responsible for apoptosis and/or autophagy and caspase‐3 activation were found to be tyrosinase dependent. These results suggest that a tyrosinase‐dependent accumulation of ER stress and/or activation of the apoptotic pathway may contribute to the melanocyte cytotoxicity. 相似文献
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Bloom of a denitrifying methanotroph, ‘Candidatus Methylomirabilis limnetica’, in a deep stratified lake 下载免费PDF全文
Jon S. Graf Magdalena J. Mayr Hannah K. Marchant Daniela Tienken Philipp F. Hach Andreas Brand Carsten J. Schubert Marcel M. M. Kuypers Jana Milucka 《Environmental microbiology》2018,20(7):2598-2614
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S. K. Srivastava 《Nordic Journal of Botany》1994,14(1):51-53
A new species Garcinia dhanìkharíensis (Clusiaceae) from South Andaman, India is described and illustrated. 相似文献
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《Zoological Journal of the Linnean Society》1903,29(188):90-107
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The ability to withstand viral predation is critical for survival of most microbes. Accordingly, a plethora of phage resistance systems has been identified in bacterial genomes (Labrie et al, 2010 ), including restriction‐modification systems (R‐M) (Tock & Dryden, 2005 ), abortive infection (Abi) (Chopin et al, 2005 ), Argonaute‐based interference (Swarts et al, 2014 ), as well as clustered regularly interspaced short palindromic repeats (CRISPR) and associated protein (Cas) adaptive immune system (CRISPR‐Cas) (Barrangou & Marraffini, 2014 ; Van der Oost et al, 2014 ). Predictably, the dark matter of bacterial genomes contains a wealth of genetic gold. A study published in this issue of The EMBO Journal by Goldfarb et al ( 2015 ) unveils bacteriophage exclusion (BREX) as a novel, widespread bacteriophage resistance system that provides innate immunity against virulent and temperate phage in bacteria. 相似文献
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Armando J. Ubeda C. A. Simpfendorfer M. R. Heupel 《Environmental Biology of Fishes》2009,84(3):293-303
The movement of bonnetheads, Sphyrna tiburo, within an estuarine system on the Gulf of Mexico coast of Florida was examined to define response to salinity change. Shark
presence and movements were evaluated by acoustic monitoring and gillnet sampling. Acoustic monitoring data were used to investigate
active selection of different zones within the estuary based on differences in salinity among zones. Sharks were monitored
for 187 days in 2003 and 217 days in 2004 in salinities ranging from 11.0 to 31.0 ppt in 2003 and 15.8 to 34.6 ppt in 2004.
Monitoring data supported the hypothesis that salinity played a role in the distribution and movement of S. tiburo. Catch per unit effort (CPUE) data obtained from gillnet sampling from 1995 to 2004 were examined to determine affinity or
avoidance of specific salinities within the study site as calculated using an electivity index. Electivity analysis showed
almost no affinity or avoidance for specific salinity values. The difference in results between the CPUE and acoustic monitoring
in relation to the potential effects of salinity likely relate to the nature of the data, with acoustic monitoring providing
continuous data and CPUE providing snapshot location data. The results of this study suggest that although S. tiburo are collected within a wide range of salinity levels, salinity may affect movement and distribution. Salinity effects may
be more pronounced during periods of prolonged and/or large changes in salinity as detected by long-term monitoring. 相似文献
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Fábio Cristiano Angonesi Brod Javier Vernal Jean Borges Bertoldo Hernán Terenzi Ana Carolina Maisonnave Arisi 《Molecular biotechnology》2010,44(3):242-249
Lactobacillus plantarum is an important lactic acid bacterium, usually found as natural inhabitant of food, such as fermented vegetables and meat
products. However, little information about lactic acid bacteria, especially concerning L. plantarum, as a source of useful enzymes has been reported. The aim of this study was to clone, express in Escherichia coli, purify, and characterize an esterase from L. plantarum ATCC 8014. The esterase gene (1014 bp) was amplified and cloned in pET14b expression vector to express a His6-tagged protein in E. coli. Recombinant L. plantarum esterase was purified by Ni-NTA resin, presenting an apparent molecular mass of about 38 kDa. It presented highest activity
at pH 6.0 and 40°C. Also, it presented preference for p-nitrophenyl butyrate, but hydrolyzed more efficiently p-nitrophenyl acetate. Besides, this study shows, for the first time, CD data about secondary structure of an esterase from
L. plantarum. 相似文献