U.S. graduate education. Cornell's plans for the Big Apple rely on quality, cash, and dreams     

Kean S 《Science (New York, N.Y.)》2012,335(6064):26-27

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Population structure of the rice sheath blight pathogen <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-1 IA from India   总被引：1，自引：0，他引：1  

Celeste?C.?LindeEmail author  Marcello?Zala  R.S.?David?Paulraj  Bruce?A.?McDonald  Sam?S.?Gnanamanickam 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(2):113-121

The population structure of Rhizoctonia solani AG-1 IA causing rice sheath blight from India was evaluated for 96 isolates using seven RFLP loci. Nineteen of the isolates did not hybridise to R. solani AG-1 IA RFLP probes and rDNA analyses subsequently confirmed that they were either Ceratobasidium oryzae-sativae isolates or another Rhizoctonia sp. The population structure of the remaining 77 R. solani AG-1 IA Indian isolates was similar to that of a previously characterized Texas population. Clonal dispersal of R. solani AG-1 IA in India was moderate within fields and no clones were shared among field populations. Low levels of population subdivision and small genetic distances among populations were consistent with high levels of gene flow. Frequent sexual reproduction was indicated by the fact that most populations were in Hardy–Weinberg equilibrium (HWE). The two loci (R68 and R111) that deviated significantly from HWE showed an excess of heterozygosity. Although Texas and Indian populations were geographically very distant, they exhibited only moderate population subdivision, with an F_ST value of 0.193.  相似文献   

Occurrence of rift valley fever in cattle in Ijara district,Kenya     

Nelson O. Owange  William O. Ogara  Hippolyte Affognon  Gathura B. Peter  Jacqueline Kasiiti  Sam Okuthe  W. Onyango-Ouma  Tobias Landmann  Rosemary Sang  Murithi Mbabu 《Preventive veterinary medicine》2014

Ijara district in Kenya was one of the hotspots of rift valley fever (RVF) during the 2006/2007 outbreak which led to human and animal deaths causing huge economic and public health losses. The main constraint in the control and prevention of RVF is inadequate knowledge on its occurrence during the interepidemic period. This study was aimed at understanding the occurrence of RVF in cattle in Ijara to enable the development of improved community-based disease surveillance, prediction, control and prevention.  相似文献   

Social and ecological complexity is associated with gestural repertoire size of wild chimpanzees     

Sam G. B. ROBERTS  Anna I. ROBERTS 《Integrative zoology》2020,15(4):276-292

Increasing our understanding of primate gestural communication can provide new insights into language evolution. A key question in primate communication is the association between the social relationships of primates and their repertoire of gestures. Such analyses can reveal how primates use their repertoire of gestural communication to maintain their networks of family and friends, much as humans use language to maintain their social networks. In this study we examined the association between the repertoire of gestures (overall, manual and bodily gestures, and gestures of different modalities) and social bonds (presence of reciprocated grooming), coordinated behaviors (travel, resting, co‐feeding), and the complexity of ecology (e.g. noise, illumination) and sociality (party size, audience), in wild East African chimpanzees (Pan troglodytes schweinfurthii). A larger repertoire size of manual, visual gestures was associated with the presence of a relationship based on reciprocated grooming and increases in social complexity. A smaller repertoire of manual tactile gestures occurred when the relationship was based on reciprocated grooming. A smaller repertoire of bodily gestures occurred between partners who jointly traveled for longer. Whereas gesture repertoire size was associated with social complexity, complex ecology also influenced repertoire size. The evolution of a large repertoire of manual, visual gestures may have been a key factor that enabled larger social groups to emerge during evolution. Thus, the evolution of the larger brains in hominins may have co‐occurred with an increase in the cognitive complexity underpinning gestural communication and this, in turn, may have enabled hominins to live in more complex social groups.  相似文献   

Literary criticism. Red in tooth and claw among the literati     

Kean S 《Science (New York, N.Y.)》2011,332(6030):654-656

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湖南省主要旱地土壤供钾能力的研究   总被引：7，自引：1，他引：7  

郑圣先  李明德 《中国农业科学》1995,28(2):43-50

 通过对土壤的粘土矿物、含钾矿物、钾素含量状况和供钾特性进行分析，阐明了湖南省主要旱地土壤的供钾能力。土壤全钾、缓效钾和速效钾的含量分别为1.44%-2.75%、160.4-479.5mg/kg和61.9-114.2mg/kg、钾素含量与母质、粘土矿物组成和含钾矿物的含量有关。研究表明，以高岭石为主的土壤，其缓冲容量较低，钾释放速率小，在耗竭试验中，经4-5次收获后，玉米的干物质产量和吸钾量明显下降，田间施钾效果极为显著。以伊利石为主的土壤，其缓冲容量大，耗竭过程中玉米可得到持续高产和吸取较多的钾，田间施钾效果不明显。在湖南省主要旱地土壤上，除紫色页岩和湖积物发育的旱土供钾能力较高外，其它母质发育的旱土都表现出缺钾。  相似文献   

Focused evolution of HIV-1 neutralizing antibodies revealed by structures and deep sequencing     

Wu X  Zhou T  Zhu J  Zhang B  Georgiev I  Wang C  Chen X  Longo NS  Louder M  McKee K  O'Dell S  Perfetto S  Schmidt SD  Shi W  Wu L  Yang Y  Yang ZY  Yang Z  Zhang Z  Bonsignori M  Crump JA  Kapiga SH  Sam NE  Haynes BF  Simek M  Burton DR  Koff WC  Doria-Rose NA  Connors M;NISC Comparative Sequencing Program  Mullikin JC  Nabel GJ  Roederer M  Shapiro L  Kwong PD  Mascola JR 《Science (New York, N.Y.)》2011,333(6049):1593-1602

Antibody VRC01 is a human immunoglobulin that neutralizes about 90% of HIV-1 isolates. To understand how such broadly neutralizing antibodies develop, we used x-ray crystallography and 454 pyrosequencing to characterize additional VRC01-like antibodies from HIV-1-infected individuals. Crystal structures revealed a convergent mode of binding for diverse antibodies to the same CD4-binding-site epitope. A functional genomics analysis of expressed heavy and light chains revealed common pathways of antibody-heavy chain maturation, confined to the IGHV1-2*02 lineage, involving dozens of somatic changes, and capable of pairing with different light chains. Broadly neutralizing HIV-1 immunity associated with VRC01-like antibodies thus involves the evolution of antibodies to a highly affinity-matured state required to recognize an invariant viral structure, with lineages defined from thousands of sequences providing a genetic roadmap of their development.  相似文献   

Land-use allocation protects the Peruvian Amazon   总被引：2，自引：0，他引：2  

Oliveira PJ  Asner GP  Knapp DE  Almeyda A  Galván-Gildemeister R  Keene S  Raybin RF  Smith RC 《Science (New York, N.Y.)》2007,317(5842):1233-1236

Disturbance and deforestation have profound ecological and socioeconomic effects on tropical forests, but their diffuse patterns are difficult to detect and quantify at regional scales. We expanded the Carnegie forest damage detection system to show that, between 1999 and 2005, disturbance and deforestation rates throughout the Peruvian Amazon averaged 632 square kilometers per year and 645 square kilometers per year, respectively. However, only 1 to 2% occurred within natural protected areas, indigenous territories contained only 11% of the forest disturbances and 9% of the deforestation, and recent forest concessions effectively protected against clear-cutting. Although the region shows recent increases in disturbance and deforestation rates and leakage into forests surrounding concession areas, land-use policy and remoteness are serving to protect the Peruvian Amazon.  相似文献   

Fibre supplementation to pre-weaning piglet diets did not improve the resilience towards a post-weaning enterotoxigenic E. coli challenge     

Hubèrt van Hees  Dominiek Maes  Sam Millet  Leo den Hartog  Theo van Kempen  Geert Janssens 《Journal of animal physiology and animal nutrition》2021,105(2):260-271

Dietary fibre (DF) is implicated in gastrointestinal health of weaned piglets, either through its physiochemical properties, through modulation of gut microbiota and (or) improved gut integrity. We aimed to study the effect of DF enriched supplemental diets fed to suckling piglets (‘creep feed’) on health and performance after weaning when challenged with an enterotoxigenic E. coli (ETEC). Seventy-two piglets originating from 28 litters had been fed four creep diets, that is a low-fibre control (CON); a diet containing 2% long-chain arabinoxylans from wheat (lc-AXOS) or 5% purified cellulose (CELL) or a diet containing the high fermentable and the low-fermentable fibre source (i.e. 2% lc-AXOS and 5% CELL). Upon weaning, piglets were individually housed and all fed the same diet. On days 7, 8 and 9, animals received an oral dose of ETEC (5 ml containing 10⁷ to 10⁸ CFU/ml). Besides growth performance, faecal and skin scores were recorded daily. Gut permeability was assessed by urinary excretion of Co-EDTA prior and post-ETEC challenge. Repeated measures in time were statistically evaluated with generalized linear mixed models. We used a binominal distribution for evaluating the faecal and skin scores. Feed intake and body weight gain did not differ between treatments (p > .05). Piglets on CELL decreased gain:feed ratio in week 2 + 3 week compared to CON (p = .035). Prior to ETEC challenge, gut permeability tended to increase for lc-AXOS (p = .092). Moreover, lc-AXOS as main effect increased intestinal permeability before ETEC challenge (p = .013), whereas the low-fermentable fibre lead to elevated intestinal permeability after ETEC challenge (p = .014). The incidence of diarrhoea was higher for lc-AXOS + CELL compared with lc-AXOS (p = .036), while skin condition was unaffected. In conclusion, neither the high fermentable nor the low-fermentable fibre source improved post-weaning growth or gastrointestinal health of the piglets.  相似文献   

Heavy Metal Determination in Atmospheric Deposition and Other Fluxes in Northern France Agrosystems     

Azimi  Sam  Cambier  Philippe  Lecuyer  Isabelle  Thevenot  Daniel 《Water, air, and soil pollution》2004,157(1-4):295-313

Water, Air, &; Soil Pollution - The aim of this study is to assess the annual balance of the fluxes of Cd, Cu, Ni, Pb and Zn within different cropping systems, in an experimental site located...  相似文献