In vitro biosynthesis of fatty acids of blood lipids from ducks infected with Plasmodium lophurae     

K S Mandhare  G T Dimopoullos  L T Hart 《Avian diseases》1973,17(3):617-622

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OBSERVATIONS ON THE EFFECTS OF IMPLANTATION OF PROGESTERONE—OESTRADIOL BENZOATE ON CATTLE FATTENING UNDER QUEENSLAND FEEDLOT CONDITIONS     

By W. J.  Pryor  B.V.Sc. B.  Hart  B.V.Sc.† 《Australian veterinary journal》1961,37(9):342-345

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THE ETIOLOGY OP ABORTION IN DAIRY CATTLE IN VICTORIA     

D. D. Leaver  B.V.Sc I. H. Hart  B.V.Sc 《Australian veterinary journal》1960,36(2):46-48

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Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis   总被引：1，自引：0，他引：1  

Mense MG  Van De Verg LL  Bhattacharjee AK  Garrett JL  Hart JA  Lindler LE  Hadfield TL  Hoover DL 《American journal of veterinary research》2001,62(3):398-405

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.  相似文献   

Antimicrobial resistance in Campylobacter spp., Escherichia coli and enterococci associated with pigs in Australia     

Hart WS  Heuzenroeder MW  Barton MD 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2004,51(5):216-221

The major influences on the amplification and spread of antibiotic-resistant bacteria are the therapeutic use of antibiotics in human medicine and their use in livestock for therapy, prophylaxis and growth promotion. The use of veterinary antibiotics has many benefits to the livestock industries ensuring animal health and welfare, but use at subtherapeutic levels also exerts great selective pressure on emergence of resistant bacteria. The possible effect on human health is a problem of current debate. This study involved sampling pig carcasses, pig meat and assessing the level of resistance in zoonotic enteric bacteria of concern to human health. In South Australian pigs, thermophilic Campylobacter species showed widespread resistance (60-100%) to tylosin, erythromycin, lincomycin, ampicillin and tetracycline. No resistance was seen to ciprofloxacin. The enterococci demonstrated little resistance (0-30%) to vancomycin or virginiamycin, but the overall results from the antibiotic sensitivity testing of the enterococci have demonstrated how widespread their resistance has become. Escherichia coli strains showed widespread resistance to tetracycline and moderately common resistance (30-60%) to ampicillin and sulphadiazine. Resistance to more than one antibiotic was common. Pigs from New South Wales were also sampled and differences in resistance patterns were noted, perhaps reflecting different antibiotic use regimens in that state.  相似文献   

Reciprocal rewards stabilize cooperation in the mycorrhizal symbiosis     

Kiers ET  Duhamel M  Beesetty Y  Mensah JA  Franken O  Verbruggen E  Fellbaum CR  Kowalchuk GA  Hart MM  Bago A  Palmer TM  West SA  Vandenkoornhuyse P  Jansa J  Bücking H 《Science (New York, N.Y.)》2011,333(6044):880-882

Plants and their arbuscular mycorrhizal fungal symbionts interact in complex underground networks involving multiple partners. This increases the potential for exploitation and defection by individuals, raising the question of how partners maintain a fair, two-way transfer of resources. We manipulated cooperation in plants and fungal partners to show that plants can detect, discriminate, and reward the best fungal partners with more carbohydrates. In turn, their fungal partners enforce cooperation by increasing nutrient transfer only to those roots providing more carbohydrates. On the basis of these observations we conclude that, unlike many other mutualisms, the symbiont cannot be "enslaved." Rather, the mutualism is evolutionarily stable because control is bidirectional, and partners offering the best rate of exchange are rewarded.  相似文献   

Equatorial X-ray Emissions: Implications for Jupiter's High Exospheric Temperatures     

JH Waite  GR Gladstone  WS Lewis  P Drossart  TE Cravens  AN Maurellis  BH Mauk  S Miller 《Science (New York, N.Y.)》1997,276(5309):104-108

Observations with the High Resolution Imager on the Rontgensatellit reveal x-ray emissions from Jupiter's equatorial latitudes. The observed emissions probably result from the precipitation of energetic (>300 kiloelectron volts per atomic mass unit) sulfur and oxygen ions out of Jupiter's inner radiation belt. Model calculations of the energy deposition by such heavy ion precipitation and of the resulting atmospheric heating rates indicate that this energy source can contribute to the high exospheric temperatures(>800 kelvin at 0.01 microbar) measured by the Galileo probe's Atmospheric Structure Instrument. Low-latitude energetic particle precipitation must therefore be considered, in addition to other proposed mechanisms such as gravity waves and soft electron precipitation, as an important source of heat for Jupiter's thermosphere.  相似文献   

Mate selection and the evolution of highly polymorphic self/nonself recognition genes     

Grosberg RK  Hart MW 《Science (New York, N.Y.)》2000,289(5487):2111-2114

Multicellular organisms use the products of highly polymorphic genes to distinguish self from conspecific nonself cells or tissues. These allorecognition polymorphisms may regulate somatic interactions between hosts and pathogens or between competitors (to avoid various forms of parasitism), as well as reproductive interactions between mates or between gametes (to avoid inbreeding). In both cases, rare alleles may be advantageous, but it remains unclear which mechanism maintains the genetic polymorphism for specificity in self/nonself recognition. Contrary to earlier reports, we show that mate selection cannot be a strong force maintaining allorecognition polymorphism in two colonial marine invertebrates. Instead, the regulation of intraspecific competitive interactions appears to promote the evolution of polymorphisms in these species.  相似文献   

Conserved genetic basis of a quantitative plumage trait involved in mate choice     

Mundy NI  Badcock NS  Hart T  Scribner K  Janssen K  Nadeau NJ 《Science (New York, N.Y.)》2004,303(5665):1870-1873

A key question in evolutionary genetics is whether shared genetic mechanisms underlie the independent evolution of similar phenotypes across phylogenetically divergent lineages. Here we show that in two classic examples of melanic plumage polymorphisms in birds, lesser snow geese (Anser c. caerulescens) and arctic skuas (Stercorarius parasiticus), melanism is perfectly associated with variation in the melanocortin-1 receptor (MC1R) gene. In both species, the degree of melanism correlates with the number of copies of variant MC1R alleles. Phylogenetic reconstructions of variant MC1R alleles in geese and skuas show that melanism is a derived trait that evolved in the Pleistocene.  相似文献   

Costae of Tritrichomonas foetus: purification and chemical composition   总被引：1，自引：0，他引：1  

W E Sledge  A D Larson  L T Hart 《Science (New York, N.Y.)》1978,199(4325):186-188

The costa is an intracellular organelle common to all trichomonads. Costae from Tritrichomonas foetus have been purified by a method which involves lysis of T. foetus with the heat-stable hemolysin produced by Pseudomonas aeruginosa, followed by differential centrifugation. Analysis of the purified costae demonstrated that the organelle is composed of 95 percent carbohydrate and 5 percent protein. The carbohydrate moiety, probably a polysaccharide, consisted of glucose (95 percent), mannose (0.4 percent), glucosamine (1.4 percent), ribose (0.6 percent), and an unidentified sugar (2.6 percent). The kinetosomal complex was attached to the costa after initial lysis of cells but was separated from the costa during purification.  相似文献