Improved insect‐proofing: expressing double‐stranded RNA in chloroplasts          下载免费PDF全文

Julia Bally  Elane Fishilevich  Andrew J Bowling  Heather E Pence  Kenneth E Narva  Peter M Waterhouse 《Pest management science》2018,74(8):1751-1758

RNA interference (RNAi) was discovered almost 20 years ago and has been exploited worldwide to silence genes in plants and animals. A decade later, it was found that transforming plants with an RNAi construct targeting an insect gene could protect the plant against feeding by that insect. Production of double‐stranded RNA (dsRNA) in a plant to affect the viability of a herbivorous animal is termed trans‐kingdom RNAi (TK‐RNAi). Since this pioneering work, there have been many further examples of successful TK‐RNAi, but also reports of failed attempts and unrepeatable experiments. Recently, three laboratories have shown that producing dsRNA in a plant's chloroplast, rather than in its cellular cytoplasm, is a very effective way of delivering TK‐RNAi. Our review examines this potentially game‐changing approach and compares it with other transgenic insect‐proofing schemes. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

Soil pore volume and the abundance of soil mites in two contrasting habitats     

Uffe N. Nielsen  Graham H.R. Osler  René van der Wal  Colin D. Campbell  David F.R.P. Burslem 《Soil biology & biochemistry》2008,40(6):1538-1541

Microarthropods are mainly found in the organic layer of soils but show high spatial variability in abundance that remains poorly understood. A factor that could be influencing the abundance of microarthropods is the soil pore volume. Consequently, we tested the hypothesis that mite abundance is related to soil pore volume in two contrasting habitats. Heather moorland and birch woodland, with contrasting humus forms, showed high within-habitat variation in soil pore volume and mite abundance. The abundance of oribatid mites in both habitats and the abundance of mesostigmatid mites in heather moorland were strongly and positively related to the volume of pores in the range 60–300 μm. This supports the hypothesis that mite abundance is influenced by soil pore volume and we stress that soil structure should be considered as an explanatory variable when studying microarthropod communities.  相似文献   

WHO 2006 child growth standards: implications for the prevalence of stunting and underweight-for-age in a birth cohort of Gabonese children in comparison to the Centers for Disease Control and Prevention 2000 growth charts and the National Center for Health Statistics 1978 growth references     

Schwarz NG  Grobusch MP  Decker ML  Goesch J  Poetschke M  Oyakhirome S  Kombila D  Fortin J  Lell B  Issifou S  Kremsner PG  Klipstein-Grobusch K 《Public health nutrition》2008,11(7):714-719

OBJECTIVES: To assess the proportion of children being stunted and underweight-for-age at 3, 9 and 15 months in Lambaréné, Gabon, using the WHO child growth standards released in 2006 as compared with the Centers for Disease Control and Prevention (CDC) 2000 and the National Center for Health Statistics (NCHS) 1978 child growth charts/references. DESIGN AND SETTING: Prospective birth cohort in Lambaréné, Gabon. SUBJECTS: Two hundred and eighty-nine children from birth to 15 months of age. METHODS: Weight and length were recorded at 3, 9 and 15 months. Corresponding Z scores for stunting and underweight-for-age were calculated for the three different standards/references. Children with a height-for-age or weight-for-age below -2 SD of the corresponding reference median (Z score < or = -2) were classified as stunted or underweight-for-age, respectively. RESULTS: With the new WHO 2006 standards a higher proportion (4.0%) of 3-month-old infants were underweight compared with the CDC (1.0%) or the NCHS (0.7%) child growth charts/references. In contrast to the NCHS references or the CDC charts, this proportion did not increase from 3 to 9 months or from 9 to 15 months. The proportion of children being stunted was highest (above 20%) with the WHO 2006 standards at all three ages. Again, in contrast to the old standards, this proportion did not increase from 3 to 9 months or from 9 to 15 months. CONCLUSIONS: The present results show considerably different growth faltering patterns for Gabonese children depending on the growth charts used to assess the prevalence of stunting and underweight. Shifting to the new WHO child growth standards may have important implications for child health programmes.  相似文献   

Viability and patch occupancy of a swamp rabbit metapopulation at the northern edge of its distribution     

Charlotte L. Roy Nielsen  Sarah M. Wakamiya  Clayton K. Nielsen   《Biological conservation》2008,141(4):1043-1054

Swamp rabbits (Sylvilagus aquaticus) are state-endangered in Indiana, USA, and population decline has been attributed to habitat loss. We conducted pellet surveys as part of a long-term survey effort that has been conducted at approximate 10-year intervals over the last 40 years. We modeled patch occupancy and conducted a spatially-explicit population viability analysis (PVA). Although occupancy of individual patches varied over time, occupancy rate has been constant for the last 30 years, and Indiana swamp rabbits exist as a metapopulation that appears to be stable. Metapopulation dynamics were best characterized as being stationary, but area was an important factor in extinction rates; occupied patches (142 ± 37 ha) were significantly larger (P = 0.01) than unoccupied patches (79 ± 20 ha). We did not find strong support for models with colonization rates as a function of distance to neighboring patches, nor was distance to contiguous patches of habitat significantly different (P = 0.12) for occupied and unoccupied sites. Population viability analysis corroborated our findings based on occupancy modeling, and evaluation of the PVA model using occupancy data for the period 1985–2006 resulted in predictions that nearly matched our field observations (33% observed patch occupancy vs. 25% predicted patch occupancy). Population viability was most sensitive to reductions in survival and fecundity rates, but was otherwise robust to changes in parameters such as initial abundance and carrying capacity. Our findings provide novel insights into a poorly studied member of Sylvilagus and into species metapopulation dynamics at the edge of the range.  相似文献   

Can natural disturbance-based forestry rescue a declining population of grizzly bears?     

Scott E. Nielsen  Gordon B. Stenhouse 《Biological conservation》2008,141(9):2193-2207

Forest managers are increasingly considering historic patterns of natural forest disturbance as a model for forest harvesting and as a coarse-filter ecosystem management tool. We evaluated the long-term (100-year) persistence of a grizzly bear population in Alberta, Canada using forest simulations and habitat modelling. Even with harvesting the same volume of timber, natural disturbance-based forestry resulted in a larger human footprint than traditional two-pass forestry with road densities reaching 1.39 km/km² or more than three times baseline conditions and suggested maximum levels of security for grizzly bears. Because bears favour young forests and edges where food resources are plentiful, a future shift to young forests and more edge habitat resulted in a 20% projected increase in habitat quality and a 10% projected increase in potential carrying capacity. Human-caused mortality risk, however, offset any projected gains in habitat and carrying capacity resulting in the loss of all secure, unprotected territories, regardless of forest harvest method, within the first 20-30 years of simulation. We suggest that natural disturbance-based forestry is an ill-suited management tool for sustaining declining populations of grizzly bears. A management model that explicitly considers road access is more likely to improve grizzly bear population persistence than changing the size of clear-cuts. In fact, large clear cuts might be counter productive for bears since a diversity of habitats within each bear’s home range is more likely to buffer against future uncertainties.  相似文献   

Linking colonies to fisheries: Spatio-temporal overlap between common murres (Uria aalge) from Tatoosh Island and coastal gillnet fisheries in the Pacific Northwest, USA     

Nathalie J. Hamel  Julia K. Parrish 《Biological conservation》2008,141(12):3101-3115

The population-level impact of seabird bycatch is difficult to assess because colony-of-origin is often unknown. As an alternative and complementary approach to ship-derived observations, we assessed the relative potential for bycatch of a known seabird population by quantifying spatio-temporal overlap with local fisheries. Common murres (Uria aalge) have been reported as the most abundant seabird inadvertently caught in Washington and British Columbia coastal gillnet fisheries. In 1999-2001, we tracked 48 common murres from Tatoosh Island, the closest colony to the fisheries, during post-breeding. Using capture-mark-recapture models, we estimated weekly murre movement probabilities to/from three strata (offshore of, centered around, and inshore of Tatoosh Island). Based on movement probabilities and population size, we projected strata- and week-specific murre abundance. We created an index of overlap by calculating the product of murre abundance × gillnet fishing effort as a function of strata and time. The majority of murres (80%) moved inshore, where fishing effort was consistently the highest, suggesting that up to 4000 Tatoosh murres were vulnerable to bycatch. Index scores in the inshore stratum were 5-25 times higher relative to the offshore and Tatoosh strata, respectively. Overlap was sensitive to phenology, as index scores increased by 50% when dispersal was shifted four weeks earlier, while a two weeks delay decreased scores by 20%. Until the long-term impact of cumulative mortality in gillnet fisheries is determined, we believe a precautionary approach is warranted in the inshore stratum where the potential for bycatch was highest. We advocate the use of visible netting in inshore fisheries, a proven solution that reduces murre bycatch while maintaining fishing efficiency.  相似文献   

Headspace solid-phase microextraction gas chromatography-mass spectrometry analysis of volatiles in orujo spirits from a defined geographical origin     

Peña RM  Barciela J  Herrero C  García-Martín S 《Journal of agricultural and food chemistry》2008,56(8):2788-2794

A headspace solid-phase microextraction (HS-SPME) and gas chromatography-selective ion monitoring/mass spectrometry (GC-SIM/MS) method was optimized for analysis of 22 volatile compounds in orujo spirit samples from the Geographic Denomination "Orujo de Galicia/Augardente de Galicia". HS-SPME experimental conditions, such as fiber coating, extraction temperature, extraction and pre-equilibrium time, sample volume, and the presence of salt, were studied to improve the extraction process. The best results were obtained using a 65 microm Carbowax-divinylbenzene fiber during a headspace extraction at 40 degrees C with constant magnetic stirring for 15 min and after a 5 min period of pre-equilibrium time. The sample volume was 6 mL of orujo containing 25% of NaCl, placed in 12 mL glass vials equipped with a screw cap and PTFE/silicone septum. Desorption was performed directly in the gas chromatograph injector port for 5 min at 250 degrees C using the splitless mode. The proposed method is sensible (with detection limits between 0.0045 and 0.2399 mg/L), precise (with coefficients of variation in the range 0.99-8.18%), and linear over more than 1 order of magnitude. The developed method presented recoveries comprised between 76.0 and 112.4%. The applicability of the new method was demonstrated by determining the considered 22 volatile compounds in nine orujo commercial samples with quality and origin brands.  相似文献   

Development of a LC-MS/MS method for the analysis of enniatins and beauvericin in whole fresh and ensiled maize     

Sørensen JL  Nielsen KF  Rasmussen PH  Thrane U 《Journal of agricultural and food chemistry》2008,56(21):10439-10443

A LC-MS/MS method for the detection of beauvericin and the four enniatins A, A1, B, and B1 in maize and maize silage was developed. The method uses direct injection of maize extracts without any tedious and laborious cleanup procedures. The limit of quantification was determined at 13 ng g(-1) for beauvericin and at 17, 34, 24, and 26 ng g(-1) for enniatins A, A1, B, and B1, respectively. The method was used in surveys of the compounds in fresh maize samples collected at harvest in 2005 and 2006. All samples had the same distribution of the enniatins: B > B1 > A1 > A. Enniatin B was present in 90% of the samples in 2005 and in 100% in 2006 at levels up to 489 and 2598 ng g(-1), respectively. Beauvericin contamination was more frequently detected in 2006 than in 2005 (89 and 10%, respectively) and in higher amounts (988 and 71 ng g(-1), respectively). The occurrence of beauvericin and the four enniatins was examined in 3-month-old maize silage stacks from 20 different farms. As observed in fresh maize, enniatin B was the most abundant compound in ensiled maize and was found from 19 stacks at levels up to 218 ng g(-1). The stability of enniatin B in maize silage was assessed by analyzing samples from 10 of the silage stacks taken after 3, 7, and 11 months of ensiling. Enniatin B could be detected at all locations after 11 months and appeared to be stable during ensiling.  相似文献   

Manual geo-rectification to improve the spatial accuracy of ortho-mosaics based on images from consumer-grade unmanned aerial vehicles (UAVs)     

Azim  Saiful  Rasmussen  Jesper  Nielsen  Jon  Gislum  René  Laursen  Morten Stigaard  Christensen  Svend 《Precision Agriculture》2019,20(6):1199-1210

Precision Agriculture - The global spatial accuracy of ortho-mosaics based on images from consumer-grade unmanned aerial vehicles (UAVs) is relatively low. The use of ground control points (GCPs)...  相似文献   

Suspended matter and associated contaminants in Danish streams: a national analysis     

Thodsen  Hans  Rasmussen  Jes Jessen  Kronvang  Brian  Andersen  Hans Estrup  Nielsen  Anders  Larsen  Søren Erik 《Journal of Soils and Sediments》2019,19(7):3068-3082

Purpose

Suspended matter (SM) in streams is usually considered of minor importance in Danish environmental management. However, SM has some ecological effects as it may (1) clog fish spawning grounds and (2) act as an important agent for transport and exposure of biota to chemical substances, such as phosphorus and toxic inorganic (e.g. heavy metals) and organic (e.g. pesticides) substances.

Materials and methods

A large national data set of >?100,000 water samples analysed for SM and loss on ignition was investigated for spatial concentration patterns, sediment yields and temporal trends. Moreover, the importance of SM as a transport agent for phosphorus and heavy metals in streams was investigated through a correlation analysis.

Results and discussion

The mean suspended matter concentration (SMC) (including organic matter) amounted to 12 mg l^?1, with an organic content of 4.9 mg l^?1 (41%). A clear difference in SMC temporal trends over the sampling period was found between geographical regions. Sediment yields were calculated for all major catchments revealing low sediment yields (1–15 t km^?2 year^?1) compared to neighbouring countries and showed clear geographical patterns. Statistically significant relationships were established between SMCs, suspended sediment concentrations (SSCs) (excluding organic matter) and organic matter concentrations (OMCs) and particulate phosphorus (PP) concentrations, and again spatial patterns appeared. However, it was clearly shown that SMC/SSC/OMC could not be used as a robust, nationwide, indicator for PP concentrations. Analyses of the relationship between SMC and particle-bound heavy metal concentrations generally revealed weak correlations except for Pb and Ni (median R²?>?0.3).

Conclusions

Relatively low SM concentrations and sediment yields were found. SM is, in some geographical regions, an important transport agent for PP. Clear geographical patterns occurred in the relationships between SMC/SSC/OMC and both river water discharge and PP, as well as for sediment yields and for temporal trends in SMC.

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