Global transposon mutagenesis and a minimal Mycoplasma genome     

Hutchison CA  Peterson SN  Gill SR  Cline RT  White O  Fraser CM  Smith HO  Venter JC 《Science (New York, N.Y.)》1999,286(5447):2165-2169

Mycoplasma genitalium with 517 genes has the smallest gene complement of any independently replicating cell so far identified. Global transposon mutagenesis was used to identify nonessential genes in an effort to learn whether the naturally occurring gene complement is a true minimal genome under laboratory growth conditions. The positions of 2209 transposon insertions in the completely sequenced genomes of M. genitalium and its close relative M. pneumoniae were determined by sequencing across the junction of the transposon and the genomic DNA. These junctions defined 1354 distinct sites of insertion that were not lethal. The analysis suggests that 265 to 350 of the 480 protein-coding genes of M. genitalium are essential under laboratory growth conditions, including about 100 genes of unknown function.  相似文献   

The genome of the kinetoplastid parasite, Leishmania major     

Ivens AC  Peacock CS  Worthey EA  Murphy L  Aggarwal G  Berriman M  Sisk E  Rajandream MA  Adlem E  Aert R  Anupama A  Apostolou Z  Attipoe P  Bason N  Bauser C  Beck A  Beverley SM  Bianchettin G  Borzym K  Bothe G  Bruschi CV  Collins M  Cadag E  Ciarloni L  Clayton C  Coulson RM  Cronin A  Cruz AK  Davies RM  De Gaudenzi J  Dobson DE  Duesterhoeft A  Fazelina G  Fosker N  Frasch AC  Fraser A  Fuchs M  Gabel C  Goble A  Goffeau A  Harris D  Hertz-Fowler C  Hilbert H  Horn D  Huang Y  Klages S  Knights A  Kube M  Larke N  Litvin L  Lord A 《Science (New York, N.Y.)》2005,309(5733):436-442

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LMO2-associated clonal T cell proliferation in two patients after gene therapy for SCID-X1   总被引：1，自引：0，他引：1  

Hacein-Bey-Abina S  Von Kalle C  Schmidt M  McCormack MP  Wulffraat N  Leboulch P  Lim A  Osborne CS  Pawliuk R  Morillon E  Sorensen R  Forster A  Fraser P  Cohen JI  de Saint Basile G  Alexander I  Wintergerst U  Frebourg T  Aurias A  Stoppa-Lyonnet D  Romana S  Radford-Weiss I  Gross F  Valensi F  Delabesse E  Macintyre E  Sigaux F  Soulier J  Leiva LE  Wissler M  Prinz C  Rabbitts TH  Le Deist F  Fischer A  Cavazzana-Calvo M 《Science (New York, N.Y.)》2003,302(5644):415-419

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Genome sequence of the radioresistant bacterium Deinococcus radiodurans R1   总被引：1，自引：0，他引：1  

White O  Eisen JA  Heidelberg JF  Hickey EK  Peterson JD  Dodson RJ  Haft DH  Gwinn ML  Nelson WC  Richardson DL  Moffat KS  Qin H  Jiang L  Pamphile W  Crosby M  Shen M  Vamathevan JJ  Lam P  McDonald L  Utterback T  Zalewski C  Makarova KS  Aravind L  Daly MJ  Minton KW  Fleischmann RD  Ketchum KA  Nelson KE  Salzberg S  Smith HO  Venter JC  Fraser CM 《Science (New York, N.Y.)》1999,286(5444):1571-1577

The complete genome sequence of the radiation-resistant bacterium Deinococcus radiodurans R1 is composed of two chromosomes (2,648,638 and 412,348 base pairs), a megaplasmid (177,466 base pairs), and a small plasmid (45,704 base pairs), yielding a total genome of 3,284, 156 base pairs. Multiple components distributed on the chromosomes and megaplasmid that contribute to the ability of D. radiodurans to survive under conditions of starvation, oxidative stress, and high amounts of DNA damage were identified. Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.  相似文献   

Renal dysplasia,ectopic ureter,septic ureterectasia and cryptorchidism in an 11-month-old Cob colt presenting with ascending pyoureter and pyocystis     

S. L. Gough  B. S. L. Fraser  D. I. Rendle  J. J. Dixon 《Equine Veterinary Education》2021,33(8):e239-e242

An 11-month-old entire male Cob colt was presented for unilateral cryptorchid castration and intermittent purulent urethral discharge. Cystoscopy, trans-cutaneous and trans-rectal abdominal ultrasonography and contrast enhanced computed tomography examinations confirmed unilateral cryptorchidism, ipsilateral renal dysplasia and pyoureter with dilatation and ectopia. While nephrectomy may be a viable treatment approach for some cases of unilateral renal dysplasia, surgical intervention was not attempted in this case owing to financial constraints and the yearling was subjected to euthanasia. To the authors’ knowledge, this is the first report of a case of complex congenital urogenital malformation including ipsilateral renal dysplasia, pyoureter with dilatation and ectopia and cryptorchidism, a finding which has been reported more commonly in human males.  相似文献   

Effect on upland beef production of incorporating winter feeding of red clover silage or summer grazing of Molinia-dominated semi-natural pastures     

M. D. Fraser  D. A. Davies  I. A. Wright†  J. E. Vale  G. R. Nute‡  K. G. Hallett‡  R. I. Richardson‡ 《Grass and Forage Science》2007,62(3):284-300

Management systems for finishing beef cattle, designed to meet environmental goals in the Less Favoured Areas (LFAs) of the UK, often rely on the integration of grazing of semi‐natural pastures with sown permanent pasture. In this experiment, three management options were compared: (i) permanent pasture for grazing and silage production (treatment PP), (ii) permanent pasture for grazing and silage and grazing of Molinia‐dominant semi‐natural pasture in summer from June to August inclusively (treatment PP + SNP) and (iii) permanent pasture for grazing and silage and red clover (RC) silage for 0·25 of the silage requirement in winter (treatment PP + RC). The performance of spring‐born Welsh Black steers was measured from turnout in spring 2002 until finishing in summer 2003. During summer 2002, the liveweight gain of steers grazing the semi‐natural pasture was significantly lower than that of steers grazing the permanent pasture. There was a trend for the liveweight gains of the steers on the PP + SNP treatment to be higher from housing in autumn 2002, and live weights on all treatments were similar at the start of the red clover‐feeding phase. Steers offered red clover silage had a significantly higher liveweight gains than those offered grass silage, but there was only a trend for a higher live weight at the end of the winter‐feeding period. During summer 2003, liveweight gains were again higher on the permanent pasture. Finishing system significantly affected the fatty‐acid profile of the meat produced, but there was no difference in the colour of meat in relation to shelf‐life. Lipid oxidation was less for the meat from steers on the PP + SNP treatment than on the PP treatment, which, in turn, was less than for meat from the steers on the PP + RC treatment, and was in inverse proportion to the vitamin E concentration in the loin muscle. There were no significant differences in sensory panel scores for texture, juiciness or flavour of the meat.  相似文献   

Patterns of phenotypic and genetic variability show hidden diversity in Scottish Arctic charr   总被引：1，自引：1，他引：1  

C. E. Adams  D. Fraser  A. J. Wilson  G. Alexander  M. M. Ferguson  S. Skulason 《Ecology of Freshwater Fish》2007,16(1):78-86

Abstract –  This study examined the degree and pattern of variability in trophic morphology in Arctic charr ( Salvelinus alpinus L. ) at three spatial scales: across 22 populations from Scotland and between and within two adjacent catchments (Laxford and Shin) in northern Scotland. In addition, the variability at six microsatellite loci between and within the Laxford and Shin systems was determined. Habitat use by charr differed significantly between populations. The pattern of variability in trophic morphology, known to influence foraging ability in charr, showed a very high degree of between-population variation with at least 52% of population pairs showing significant differences in head shape. Trophic morphology and genetic variation was also high over small geographical scales; variation being as high between charr from lakes within the same catchment, as between adjacent catchments. The pattern of both phenotypic and genotypic variation suggests a mosaic of variation across populations with geographically close populations often as distinct from each other as populations with much greater separation. Very low levels of effective migrants between populations, even within the same catchment, suggest that this variation is being maintained by very low straying rates between phenotypically and genetically distinct populations, even when there is no apparent barrier to movement. We conclude that the genetic and phenotypic integrity of charr populations across Scotland is high and that this adaptive radiation constitutes a 'hidden' element of diversity in northern freshwater systems. Two consequences of this are that the population (rather than the species) makes a more rational unit for the consideration of conservation strategies and that the habitat requirements and therefore management needs may differ significantly between populations.  相似文献   

Bovine viral diarrhoea: Pathogenesis and diagnosis     

Sasha R. Lanyon  Fraser I. Hill  Michael P. Reichel  Joe Brownlie 《Veterinary journal (London, England : 1997)》2014,199(2):201-209

Bovine viral diarrhoea virus (BVDV) is the most prevalent infectious disease of cattle. It causes financial losses from a variety of clinical manifestations and is the subject of a number of mitigation and eradication schemes around the world. The pathogenesis of BVDV infection is complex, with infection pre- and post-gestation leading to different outcomes. Infection of the dam during gestation results in fetal infection, which may lead to embryonic death, teratogenic effects or the birth of persistently infected (PI) calves. PI animals shed BVDV in their excretions and secretions throughout life and are the primary route of transmission of the virus. These animals can usually be readily detected by virus or viral antigen detection assays (RT-PCR, ELISA), except in the immediate post-natal period where colostral antibodies may mask virus presence. PI calves in utero (the ‘Trojan cow’ scenario) currently defy detection with available diagnostic tests, although dams carrying PI calves have been shown to have higher antibody levels than seropositive cows carrying non-PI calves.Acute infection with BVDV results in transient viraemia prior to seroconversion and can lead to reproductive dysfunction and immunosuppression leading to an increased incidence of secondary disease. Antibody assays readily detect virus exposure at the individual level and can also be used in pooled samples (serum and milk) to determine herd exposure or immunity. Diagnostic tests can be used to diagnose clinical cases, establish disease prevalence in groups and detect apparently normal but persistently infected animals. This review outlines the pathogenesis and pathology of BVD viral infection and uses this knowledge to select the best diagnostic tests for clinical diagnosis, monitoring, control and eradication efforts. Test methods, types of samples and problems areas of BVDV diagnosis are discussed.  相似文献   

The influence of temperature on advective loss of Atlantic cod (Gadus morhua) eggs from the inshore environment     

Ian R. Bradbury  Paul V. R. Snelgrove  & Sandra Fraser 《Fisheries Oceanography》2001,10(4):342-352

We use a simple model of temperature-dependent egg development and mortality to develop several hypotheses concerning the effect of temperature on the occurrence of eggs of Atlantic cod, Gadus morhua , in Placentia Bay, Newfoundland. Predictions from this exploratory model were tested through a series of synoptic ichthyoplankton surveys throughout spawning and postspawning periods during 1997 and 1998. Although several egg mortality relationships were explored through the simulation, a constant mortality rate best represented the pattern observed in the two years of data. Peaks in late stage egg densities occurred in August of both 1997 and 1998 and were apparently decoupled from egg production peaks in April. We observed a decrease in mortality and the distance dispersed during egg development with increases in water temperature. We suggest that the effects of predation are small relative to the advective effects within this system, and that the interaction between advection and temperature-dependent vital rates of eggs may have dramatic consequences for coastal retention of propagules produced by inshore spawning events.  相似文献   

The genetics of plant-virus interactions: implications for plant breeding   总被引：4，自引：0，他引：4  

R. S. S. Fraser 《Euphytica》1992,63(1-2):175-185

Summary Host resistance is the main means of control of plant virus diseases. This paper reviews the genetics of resistance and matching virulence. Theoretical models of basic compatibility between plant species and their viruses, and of resistance, are described and used to predict features of resistance genetics, and mechanisms. These predictions are compared with a survey of known examples of resistance.Resistance is mainly controlled at a single genetic locus, although more complex systems are known. About half of the resistance alleles studied were dominant, the remainder were either incompletely dominant or recessive. Doubt is cast on the reliability of assessing resistance genotypes (numbers of loci and dominace relationships) from distant phenotypic measurements such as symptom severity or plant growth. A model is proposed to reconcile apparent inconsistencies between genotype and phenotype.Dominant resistance alleles are strongly associated with virus localising mechanisms normally involving local lesions. Incompletely dominant and recessive alleles allow spread of the virus, but inhibit multiplication or symptom development. Fully recessive alleles may be associated with complete immunity.Most resistance genes in the survey had been overcome by virulent virus isolates with dominant localising resistance alleles especially vulnerable. Comparatively few resistance genes have proved exceptionally durable. Acquisition of virulence can be associated with loss of general pathogenic fitness, but in some cases this can be restored by further selection of the virus in resistant hosts.Virulence/avirulence determinants have been mapped to individual base changes in different functional regions of the viral genome. A virus may contain several virulence determinants and may develop a stable gene-for-gene relationship with a host having several resistance genes. It may be possible to design robust, oligogenic resistance systems which will be difficult for the virus to overcome.  相似文献