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排序方式: 共有679条查询结果,搜索用时 343 毫秒
671.
Although scores of experiments have examined the ecological consequences of transgenic Bacillus thuringiensis (Bt) crops, debates continue regarding the nontarget impacts of this technology. Quantitative reviews of existing studies are crucial for better gauging risks and improving future risk assessments. To encourage evidence-based risk analyses, we constructed a searchable database for nontarget effects of Bt crops. A meta-analysis of 42 field experiments indicates that nontarget invertebrates are generally more abundant in Bt cotton and Bt maize fields than in nontransgenic fields managed with insecticides. However, in comparison with insecticide-free control fields, certain nontarget taxa are less abundant in Bt fields. 相似文献
672.
Riehle MM Guelbeogo WM Gneme A Eiglmeier K Holm I Bischoff E Garnier T Snyder GM Li X Markianos K Sagnon N Vernick KD 《Science (New York, N.Y.)》2011,331(6017):596-598
Population subgroups of the African malaria vector Anopheles gambiae have not been comprehensively characterized owing to the lack of unbiased sampling methods. In the arid savanna zone of West Africa, where potential oviposition sites are scarce, widespread collection from larval pools in the peridomestic human habitat yielded a comprehensive genetic survey of local A. gambiae population subgroups, independent of adult resting behavior and ecological preference. A previously unknown subgroup of exophilic A. gambiae is sympatric with the known endophilic A. gambiae in this region. The exophilic subgroup is abundant, lacks differentiation into M and S molecular forms, and is highly susceptible to infection with wild Plasmodium falciparum. These findings might have implications for the epidemiology of malaria transmission and control. 相似文献
673.
Wang W Black SS Edwards MD Miller S Morrison EL Bartlett W Dong C Naismith JH Booth IR 《Science (New York, N.Y.)》2008,321(5893):1179-1183
How ion channels are gated to regulate ion flux in and out of cells is the subject of intense interest. The Escherichia coli mechanosensitive channel, MscS, opens to allow rapid ion efflux, relieving the turgor pressure that would otherwise destroy the cell. We present a 3.45 angstrom-resolution structure for the MscS channel in an open conformation. This structure has a pore diameter of approximately 13 angstroms created by substantial rotational rearrangement of the three transmembrane helices. The structure suggests a molecular mechanism that underlies MscS gating and its decay of conductivity during prolonged activation. Support for this mechanism is provided by single-channel analysis of mutants with altered gating characteristics. 相似文献
674.
John Lester Viscara PIDE Nolissa Delmo ORGANO Andre Freire CRUZ Lilia M. FERNANDO Lucille C. VILLEGAS Evelyn F. DELFIN Michelle Ann Magat CALUBAQUIB Roselle Estera MADAYAG Erlinda S. PATERNO 《土壤圈》2023,33(5):765-775
Application of nanotechnology in agriculture has been expanded to improve crop production. The impact of nanomaterials (NMs) on factors that influence the survival and function of beneficial microorganisms is a less studied aspect that needs to be better understood. Only a few studies have assessed the effects of NMs on beneficial soil microorganisms. This study was conducted to assess the effects of nanofertilizer FertiGroe?N (FG-N) and nano-plant hormone HormoGroe?auxin (... 相似文献
675.
Relationship between biochemical markers and radiographic scores in the evaluation of the osteoarticular status of Warmblood stallions 总被引:1,自引:0,他引:1
Denis Verwilghen Valeria Busoni Monika Gangl Thierry Franck Jean-Philippe Lejeune Laurent Vanderheyden Johann Detilleux Sigrid Grulke Michelle Deberg Yves Henrotin Didier Serteyn 《Research in veterinary science》2009,87(2):319-328
Establishing the osteoarticular status of the horse is often performed by means of radiological screening of the animals. Widespread blood sampling could reveal to be an interesting alternative to this procedure which is time consuming and sometimes technically difficult. The aim of this study was to investigate the relationship between the radiological status of the horses and the levels of biochemical markers of cartilage degradation and synovial inflammation. A specific radiological scoring and classification system was therefore developed and applied on 63 stallions presented for studbook admission. Additionally, groups of horses were established according to the occurrence of osteochondrosis, degenerative joint disease and distal interphalangeal joint effusion. Insulin growth factor-I, myeloperoxidases, Coll2-1 and Coll2-1NO2 were used as blood markers. The combination of the blood parameters did not seem to correlate with the used scoring system. Coll2-1NO2 levels however tended to increase with poorer radiological class and this could therefore potentially be a useful predictor of the osteoarticular status in the horse. Coll2-1 levels were significantly higher in the degenerative joint disease group. A high percentage of horses with distal interphalangeal joint effusion was present in this study and was associated with decreased IGF-I and increased Coll2-1 levels. 相似文献
676.
Oscar Alberto Chiesa Jurgen von Bredow Michelle Smith Michael Thomas 《Research in veterinary science》2009,87(1):133-134
The purpose of this study was to simplify the two-port laparoscopic renal biopsy technique used in support of pharmacokinetic studies through the application of a one-port system. Twelve Holstein steers were fasted for 24 h and sedated with acepromazine and xylaxine in preparation for laparoscopic surgery in standing stocks. Lidocaine 2% was injected to provide local anesthesia for introduction of the trocar-cannula assembly. The operating endoscope was inserted and the abdomen was insufflated with CO2. A biopsy forceps was introduced into the channel of the operating endoscope to obtain a 100 mg kidney cortex sample. Eighteen laparoscopic procedures provided 18 kidney samples suitable for pharmacokinetic studies. No complications were encountered. The one-port laparoscopic kidney biopsy is feasible and safe, and advanced skill required for triangulation is not necessary for its performance. 相似文献
677.
678.
Olivia A. Petritz Natalie Antinoff Catherine Pfent Wayne Corapi Roy R. Pool Michelle Fabiani Sue Chen 《Journal of Exotic Pet Medicine》2013,22(3):287-292
A 4-year-old, castrated, male domestic ferret (Mustela putorius furo) was evaluated for a possible upper respiratory tract infection and wheezing for approximately 3 weeks. Supportive care for a suspected upper respiratory tract infection was initiated; however, the patient became progressively more dyspneic over the next 48 hours. A possible tracheal mass was identified upon thoracic radiographic imaging of the ferret. Tracheoscopy and a computed tomography scan of the neck and thorax confirmed the presence of a tracheal mass approximately 3 cm from the larynx obstructing 80% of the tracheal lumen. Rather than pursuing surgical resection, the owners elected humane euthanasia. An adenosquamous carcinoma of the trachea was diagnosed after histologic analysis. This tumor type has been diagnosed in the lungs of ferrets that were experimentally exposed to carcinogens found in cigarette smoke; however, there are no previous reports of this or any other tumor type associated with the ferret trachea. A tracheal mass causing a partial upper airway obstruction should be considered within the differential disease diagnosis list when a ferret is presented with dyspnea. 相似文献
679.
Anna K Farmery Ingrid E van Putten Michelle Phillipov Alistair McIlgorm 《Fish and Fisheries》2020,21(4):844-855
Consumers are being encouraged to choose sustainable seafood. In particular, eating less‐popular, under‐utilized species is promoted as a more sustainable seafood choice. This message is advocated in the media by a range of different organizations and individuals; however, evidence of greater seafood sustainability as a result of these messages is lacking. We examine current media messaging around sustainable seafood, focussing on the messages to eat more under‐utilized species, in an Australian and international context. We identify six different intended outcomes of these messages, including that eating more under‐utilized species will take pressure off heavily fished stocks, and explore the conditions under which the perceived outcomes would be realized. We use an economic lens and discuss the effect of certain aspects of consumer demand and seafood product substitutability. We propose that in order to take pressure off overfished stocks, the message to consume more under‐utilized species would need to be accompanied by messages to limit or eat less seafood. In addition, the benefits of eating more under‐utilized species as currently promoted are not always achievable and that the outcomes of some messages, if realized, could lead to overfishing of unregulated stocks and a reduction in overall fish supply. While there are many potentially positive social, economic and environmental outcomes of consuming currently under‐utilized species, media messages should encourage consumers to buy a range of seafood, including under‐utilized species, which can be traced back to a well‐managed fishery, rather than promoting under‐utilized species per se. 相似文献