Early land animals in north america: evidence from devonian age arthropods from gilboa, new york     

Shear WA  Bonamo PM  Grierson JD  Rolfe WD  Smith EL  Norton RA 《Science (New York, N.Y.)》1984,224(4648):492-494

A new fossil site near Gilboa, New York, is one of only three where fossils of terrestrial arthropods of Devonian age have been found. The new Gilboan fauna is younger than the other two but richer in taxa. Fragmentary remains and nearly whole specimens assigned to Eurypterida, Arachnida (Trigonotarbida, Araneae, Amblypygi, and Acari), Chilopoda [Craterostigmatomorpha(?) and Scuterigeromorpha(?)], and tentatively to Insecta (Archaeognatha) have been found. The centipedes and possible insects may represent the earliest records known for these groups.  相似文献   

The incidence and importance of tibial dyschondroplasia to the commercial broiler industry in Australia     

R. W. Burton  A. K. Sheridan  C. R. Howlett 《British poultry science》1981,22(2):153-160

1. To survey the relationship between tibial dyschondroplasia (TD) and the down‐grading of broiler carcasses three processing plants representing the major breeding and growing organisations in Australia were visited.

2. The incidence of TD for the three flocks examined varied from 14 to 35%. In the flock with the highest incidence of TD there was a direct relationship between the presence of TD and down‐grading of carcasses due to leg abnormalities.

3. A genetic analysis was carried out on one of the parent lines of the breeding group with the highest TD incidence. The genetic correlation between body weight and TD incidence at 7 weeks of age was negative, suggesting that continued selection for increased body weight should lead to a reduced incidence of TD. Since this conflicts with usual expectations, possible reasons, including a within‐line, genotype by environment interaction, are discussed.

4. Because of the substantial genetic component associated with TD, screening of breeding cockerels for its presence is strongly recommended.  相似文献   

Potential for using host resistance to reduce production of pseudothecia and ascospores of Leptosphaeria maculans, the blackleg pathogen of Brassica napus     

S. J. Marcroft †  S. J. Sprague  P. A. Salisbury  B. J. Howlett 《Plant pathology》2004,53(4):468-474

Pseudothecial density of the blackleg fungus Leptosphaeria maculans and discharge of ascospores was measured from stubble of a range of Brassica species, including Brassica napus (canola) cultivars, with a range of blackleg resistance. Since ascospores are the primary inoculum, these parameters reflect inoculum potential for blackleg. Stubble from a representative line of each of B. carinata , B. nigra , Sinapis alba and B. napus cv. Surpass 400 (incorporates blackleg resistance from B. rapa ssp. sylvestris ) had lower pseudothecial density and discharged fewer ascospores than stubble of other B. napus cultivars (Karoo, Oscar, Emblem, Dunkeld and Columbus). These latter B. napus cultivars and a representative B. juncea line had higher pseudothecial densities and discharged higher numbers of ascospores. If this trait of low blackleg inoculum from stubble could be introgressed into commercial canola cultivars, blackleg disease severity could be substantially reduced, resulting in higher and more stable canola yields. However, the trait of reduced ascospore discharge may not be stable, as demonstrated by the B. rapa ssp. sylvestris -derived resistance already being overcome by the blackleg fungus in Australia.  相似文献   

The inheritance of tibial dyschondroplasia in broilers     

A. K. Sheridan  C. R. Howlett  R. W. Burton 《British poultry science》1978,19(4):491-499

1. A breeding programme to develop a line of chickens with a high incidence of tibial dyschondroplasia (TD) from Australian broiler stock is described.

2. Despite the absence of a control flock, this programme has demonstrated that selection in a broiler population can rapidly increase the incidence of TD.

3. There was consistent circumstantial evidence of the presence of a major sex‐linked gene, the recessive allele of which is associated with an increased incidence of TD.

4. The realised heritability estimates (obtained in the absence of a control flock) consistently exceeded 1.00, suggesting the presence of an environmental trend favourable to the onset of TD over the four generations of this investigation.

5. There was a high maternal component or dominance genetic component, or both, for the inheritance of TD in the final generation, suggesting that environmental factors associated with the female parent line may influence the incidence of TD in broilers.  相似文献   

The Bioeconomic Potential for Agroforestry in Australia’s Northern Grazing Systems     

Peter Donaghy  Steven Bray  Rebecca Gowen  John Rolfe  Michael Stephens  Madonna Hoffmann  Anne Stunzer 《Small-Scale Forestry》2010,9(4):463-484

Although agriculture generates 16% of Australia’s greenhouse gas emissions, it also has the potential to sequester large quantities of emissions through land use management options such as agroforestry. Whilst there is an extensive amount of agroforestry literature, little has been written on the economic consequences of adopting silvopastoral systems in northern Australia. This paper reports the financial viability of adopting complementary agroforestry systems in the low rainfall region of northern Australia. The analysis incorporates the dynamic tradeoffs between tree and pasture growth, likely forest product yields, carbon sequestration and livestock methane emissions in a bioeconomic model. The results suggest there are financial benefits for landholders who integrate complementary agroforestry activities into existing grazing operations at even modest carbon prices.  相似文献   

Determining frequencies of avirulent alleles in airborne Leptosphaeria maculans inoculum using quantitative PCR     

A. P. Van de Wouw  J. F. Stonard  B. J. Howlett  J. S. West  B. D. L. Fitt  S. D. Atkins 《Plant pathology》2010,59(5):809-818

Phoma stem canker (blackleg disease) of Brassica napus (oilseed rape, canola) is caused by the fungus Leptosphaeria maculans. Frequencies of avirulent alleles for loci where virulence can be associated with gene deletion (AvrLm1 and AvrLm6) were determined in samples of L. maculans airborne ascospore inoculum using quantitative PCR. The accuracy, reproducibility and limitations of detection were determined. Changes in the frequency of avirulent alleles were determined for the 2006/2007, 2007/2008 and 2008/2009 growing seasons for winter oilseed rape in the UK. The frequency of AvrLm1 remained small (between 9% and 16%), whilst the frequency of AvrLm6 fluctuated between 35% and 66%. Estimation of frequencies of avirulent alleles in airborne pathogen inoculum gives an efficient and unbiased method to assess the potential of crop cultivars with corresponding resistance genes being at risk of disease.  相似文献   

Production and characterization of monoclonal antibodies specific for Leptospira borgpetersenii serovar hardjo type hardjobovis and Leptospira interrogans serovar hardjo type hardjoprajitno.          下载免费PDF全文

O Surujballi  C Howlett    D Henning 《Canadian journal of veterinary research》1999,63(1):62-68

Murine monoclonal antibodies were produced by immunizing BALB/c mice with a killed whole-cell antigen prepared from Leptospira borgpetersenii serovar hardjo type hardjobovis. Six of these antibodies recognized epitopes on the homologous antigen and on whole-cell antigen prepared from Leptospira interrogans serovar hardjo type hardjoprajitno. These antibodies did not cross-react with whole-cell antigens prepared from L. borgpetersenii serovar sejroe, 10 other pathogenic Leptospira serovars, or the saprophytic Leptospira biflexa serovar patoc. Three other monoclonal antibodies reacted with antigens prepared from the 2 hardjo serovars and serovar sejroe but not with antigens from the 10 other pathogenic serovars, or serovar patoc. The epitopes recognized by all of the hardjo-specific antibodies and 2 of the 3 hardjo/sejroe-specific antibodies were susceptible to sodium meta-periodate oxidation. All of the antibodies were characterized by Western blots with the hardjobovis whole-cell antigen. Each of the 9 monoclonal antibodies was inhibited from binding to the hardjobovis antigen by bovine sera which were obtained from cattle experimentally infected with hardjobovis and from field cattle, with anti-serovar hardjo microscopic agglutination test antibody titres ranging from 100 to 12800. Some of these antibodies may be suitable for incorporation into competitive enzyme immunoassays for the specific detection of antibodies to either of the hardjo serovars.  相似文献   

Seed physicochemical characteristics of field-grown US weedy red rice (Oryza sativa) biotypes: Contrasts with commercial cultivars     

David R. Gealy  Rolfe J. Bryant 《Journal of Cereal Science》2009

Red rice in the US is an aggressive weed that reduces the yield of rice and contaminates its grain. It is the same species as rice, which provides an opportunity for intercrossing. This genetic similarity complicates the management of red rice in fields and rice mills, but also indicates a potential for its use in rice breeding or niche markets. Physicochemical and cooking quality characteristics, which are important components of consumer desirability for rice, are virtually unknown for red rice. Thus, a survey of red rice accessions and rice × red rice crosses was conducted to characterize these traits. Grain amylose levels of most indigenous red rice accessions were similar to those of high amylose indica cultivars from Asia. Amylose levels in crosses were highly variable, ranging as low as those in medium-grain commercial rice to as high as those in long-grains. Alkali spreading value was generally greater in awned than in awnless red rice accessions and the aroma chemical, 2-acetyl-1-pyrroline, was detected in two red rice crosses. The generally high seed amylose levels in red rice indicate that its cooking quality would not be suitable for most common uses of US rice, but may be acceptable for niche uses.  相似文献   

Complement C5a: impact on the field of veterinary medicine     

Hezmee MN  Shiels IA  Rolfe BE  Mills PC 《Veterinary journal (London, England : 1997)》2012,192(3):264-271

Complement C5a is a pro-inflammatory polypeptide produced during activation of the complement cascade in response to foreign antigens or tissue damage secondary to physical or chemical injury. C5a, via activation of the C5a receptor (C5aR or CD88), is a major inflammatory mediator involved in a number of diseases, including some of veterinary relevance. Greater understanding of the role of C5a has been possible with the availability of gene knockout mice, specific antibodies and peptide agonists/antagonists. This review outlines the functions of C5a and its role in the development of disease, including neoplastic conditions and sepsis, in animals of veterinary importance. The application of C5aR agonist and antagonist analogues to combat those conditions is also discussed.  相似文献   

Effect of rotation of canola (Brassica napus) cultivars with different complements of blackleg resistance genes on disease severity     

P. A. Salisbury  T. D. Potter  B. J. Howlett 《Plant pathology》2012,61(5):934-944

Blackleg disease (phoma stem canker) caused by the fungus Leptosphaeria maculans is a major disease of canola (oilseed rape, Brassica napus) worldwide. Canola plants in pots were exposed to blackleg‐infested stubble of canola with different complements of resistance genes and then assessed for disease. Plant mortality was reduced when plants were exposed to stubble from a cultivar with a different complement of resistance genes compared to stubble of a cultivar with the same resistance gene. These findings were consistent with 7 years of field surveys, which showed that changes in selection pressure as a result of extensive sowing of cultivars with major‐gene resistance, termed ‘sylvestris resistance’, dramatically influenced the frequency of virulent isolates in the population towards particular resistance genes, and therefore disease severity. All these data were supported by PCR‐genotyping surveys of fungal populations whereby the frequency of virulence alleles of avirulence genes AvrLm1 and AvrLm4 changed significantly depending on the resistance gene present in the cultivar from which the isolates were cultured. This is the first example of a study showing that sowing of canola cultivars with different complements of resistance genes in subsequent years, i.e. rotation of resistance genes, minimizes disease pressure by manipulating fungal populations. This approach provides a valuable disease management strategy for canola growers and is likely to be applicable to other plant diseases.  相似文献