Equine influenza bi-annual boosters: What does the evidence tell us?     

Victoria A. Colgate  J. Richard Newton 《Equine veterinary journal》2023,55(1):147-152

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Influences of antibiotics on plantlet regeneration via organogenesis in Ioblolly pine （Pinus taeda L.）     

TANGWei LatoyaHarris RonaldJ.Newton 《林业研究》2003,14(3):185-190

Three antibiotics ampicillin, carbenicillin, and cefotaxime were evaluated for their effects on induction, growth, and differentiation of organogenic calli, as well as rooting of regenerated shoots of three Ioblolly pine (Pinus taeda L.) genotypes. Of the antibiotics administered, cefotaxime maximally increased the frequency of callus formation and growth rate of organogeni ccalli, carbenicillin maximally increased the frequency of shoot regeneration and the average number of adventitious shoots per piece of organogenic callus, ampicUlin maximally decreased the rooting frequency of regenerated shoots and mean number of roots per regenerated shoot, in comparison with antibiotic-free media. Compared with the control, ampicillin minimally increased the frequency of callus formation, cefotaxime minimally increased the frequency of shoot regeneration, and carbenicillin minimally decreased the rooting frequency of regenerated shoots in three Ioblolly pine genotypes tested. All three antibiotics increased the frequencies of callus formation and shoot regeneration, and reduced the rooting frequency ot regenerated shoots suggested that the establishment of an efficient Agrobacterium tumefaciens-mediated transformation protocol for stable integration of foreign genes into Ioblolly pine need to select a suitable antibiotic. This investigation could be useful for optimizing genetic transformation of conifers.  相似文献   

The prediction of Crumenulopsis sororia (Karst.) Groves. Incidence on lodgepole pine (Pinus contorta Dougl.) using multiple regression techniques     

A. J. Hayes  N. G. Newton  G. M. Jolly  J. Wood  M. H. Anderson 《Forest Pathology》1981,11(7):396-411

Easily-measured site variables (e. g. absolute elevation, exposure, slope and aspect) were used to prepare different regression models to predict the extent and severity of attack by C. sororia on a number of different provenances of lodgepole pine. Using a simple climatic-zone division of Scotland, a significant relationship between percentage infection on whorls 1–5, 6–10 and 11–15 and elevation, exposure and site aspect was demonstrated, whereas severity of infection was not well related with these variables in any of the models tested. This suggests that severity of infection may be influenced by other independent variables, e. g. persistence of liquid water on bark, success of spore germination and host resistance. This approach offers an opportuity to predict the possible susceptibility of different provenances of lodgepole pine under specific site conditions.  相似文献   

Evaluating Supplemental Mass Pollination Efficacy in a Lodgepole Pine Orchard in British Columbia using Chloroplast DNA Markers     

Michael Stoehr  Helga Mehl  George Nicholson  Greg Pieper  C. Newton 《New Forests》2006,31(1):83-90

Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed orchard in southern British Columbia was studied by employing four chloroplast DNA (cpDNA) markers to determine fertilization success of 10 pollen parents. SMP was conducted operationally with a bulked pollen mix twice during peak receptivity in the seed orchard. Fertilization success of the 10 SMP parents averaged 16% greater than for wind-pollinated controls in a different section of the orchard. SMP also increased the uniformity of the male contribution in treated seeds.  相似文献   

Free proline changes in Pinus taeda L. callus in response to drought stress     

Newton RJ  Sen S  Puryear JD 《Tree physiology》1986,1(3):325-332

The amino acid, proline (PRO), may have an important role in plant adaptation to drought stress. To study the effect of drought stress on PRO content of pine tissues, we measured free PRO by high pressure liquid chromatography in control ( -0.4 MPa) and drought-stressed ( -0.8, -1.0, -1.3, -1.6 MPa) callus tissue of Pinus taeda L. after eight weeks of growth. Drought stress was induced by adding polyethylene glycol (PEG) to the nutrient media. The relation between PRO accumulation and water potential was influenced by composition of the medium and temperature. Callus growing in media with water potentials of -0.8 MPa showed no increase in PRO compared to control callus in media at -0.4 MPa. When callus tissue was subjected to low water potentials (-1.6 MPa), endogenous PRO concentration increased 40-fold, while callus fresh weight decreased by more than 90%. When exogenous PRO was added to the nutrient media, endogenous PRO was directly proportional to the exogenous PRO concentration rather than reduction in callus growth. Thus low water potential in callus results in endogenous PRO accumulation and large reductions in callus fresh weight growth. Proline accumulation in pine cells appears to be related to mechanisms associated with tolerance to desiccation.  相似文献   

Seasonal variation of bulk milk somatic cell counts in UK dairy herds: investigations of the summer rise     

Green MJ  Bradley AJ  Newton H  Browne WJ 《Preventive veterinary medicine》2006,74(4):293-308

Individual cow somatic cell count (SCC) patterns were explored over a one year period in 33 dairy herds to investigate the reason for a summer rise in bulk milk somatic cell counts (BMSCC). Cow test day somatic cell counts were categorised according to the magnitude of change since the previous test day reading, to examine which categories were responsible for the summer increase. Multilevel models using Markov chain Monte Carlo methods were specified to estimate the number of somatic cells/ml produced by different cell count categories. Stage of lactation and parity were accounted for in the models. There was an increase in the proportion of cows that remained above 200,000 cells/ml for two consecutive recordings in summer and this group of cows were responsible for 70.8% of the increase in somatic cells/ml produced from May to September compared with October to March. There was no evidence that a greater new infection rate (somatic cell counts moving from below 100,000 cells/ml to over 200,000 cells/ml) contributed to the increased summer bulk milk somatic cell counts. There was no indication that a general small increase in all somatic cell counts played an important role in the increased summer somatic cell counts. Markov chain Monte Carlo methods provided a valuable and flexible platform for parameter estimation in reasonably complex multilevel models.  相似文献   

A case-control study of factors associated with pelvic and tibial stress fractures in Thoroughbred racehorses in training in the UK     

Verheyen KL  Newton JR  Price JS  Wood JL 《Preventive veterinary medicine》2006,74(1):21-35

Few epidemiological studies have investigated risk factors for musculoskeletal injury occurring in Thoroughbred racehorses during training, although it is the major cause of wastage in the racing industry. We recently conducted a large-scale epidemiological study to estimate the incidence of fracture in racehorses in training in the UK and to identify associated risk factors. Thirteen racehorse trainers provided data on horses in their care, with daily recording of training information and provision of details on any fractures incurred. Data were collected for 2 years, including two consecutive flat racing seasons (1999 and 2000). This paper describes findings from a nested case-control study investigating factors associated with the occurrence of pelvic and tibial stress fractures in our study population. Cases were identified from the main study and defined as horses with a pelvic or tibial stress fracture, confirmed through routine diagnostic imaging. Randomly selected controls were matched on date of fracture in the case. Age and gender of the horse, its exercise history and training surfaces were examined as explanatory variables. Exercise was quantified as cumulative distances cantered and worked at high speed in 30- and 60-day periods prior to date of fracture in the case. Conditional logistic regression was used to construct multivariable models for the 30- and 60-day periods, respectively. We hypothesised that larger cumulative exercise distances would be associated with an increased risk of pelvic or tibial stress fracture and that different training surfaces would be associated with differences in fracture risk. In the 30-day period, when adjusting for trainer, the risk of pelvic or tibial stress fracture increased with increasing distance cantered, reaching a peak at around 50 km, after which the risk reduced. This trend was not obvious in the 60-day period, with no significant association between exercise distances and risk of stress fracture. Predominant use of one particular sand-based all-weather surface was related to an increased risk of pelvic or tibial stress injury, although this finding should be interpreted with caution. Surface maintenance and construction may play a role; variables that were not considered in the current analyses, which were based on a relatively small number of cases. Trainer was associated with differences in stress fracture risk after adjusting for exercise distances and surface but age and gender were not.  相似文献   

A major genome region underlying artemisinin resistance in malaria     

Cheeseman IH  Miller BA  Nair S  Nkhoma S  Tan A  Tan JC  Al Saai S  Phyo AP  Moo CL  Lwin KM  McGready R  Ashley E  Imwong M  Stepniewska K  Yi P  Dondorp AM  Mayxay M  Newton PN  White NJ  Nosten F  Ferdig MT  Anderson TJ 《Science (New York, N.Y.)》2012,336(6077):79-82

Evolving resistance to artemisinin-based compounds threatens to derail attempts to control malaria. Resistance has been confirmed in western Cambodia and has recently emerged in western Thailand, but is absent from neighboring Laos. Artemisinin resistance results in reduced parasite clearance rates (CRs) after treatment. We used a two-phase strategy to identify genome region(s) underlying this ongoing selective event. Geographical differentiation and haplotype structure at 6969 polymorphic single-nucleotide polymorphisms (SNPs) in 91 parasites from Cambodia, Thailand, and Laos identified 33 genome regions under strong selection. We screened SNPs and microsatellites within these regions in 715 parasites from Thailand, identifying a selective sweep on chromosome 13 that shows strong association (P = 10(-6) to 10(-12)) with slow CRs, illustrating the efficacy of targeted association for identifying the genetic basis of adaptive traits.  相似文献   

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in hurdle starts in the UK (2001-2009)     

Reardon RJ  Boden LA  Mellor DJ  Love S  Newton JR  Stirk AJ  Parkin TD 《Equine veterinary journal》2012,44(5):564-569

Reasons for performing study: Superficial digital flexor (SDF) tendinopathy is a common injury in Thoroughbred horses racing over hurdles. Identification of risk factors may allow the introduction of measures to minimise the incidence of this injury. Objective: To identify risk factors for SDF tendinopathy in Thoroughbred horses in hurdle races in the UK. Methods: Potential risk factors for SDF tendinopathy were studied between 1 January 2001 and 31 December 2009 using a retrospective cohort study design with 1031 case starts and 168,637 control starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. Results: In the final multivariable model, 20 statistically significant risk factors were identified. Variables found to be associated with increased odds of SDF tendinopathy included: firmer going; increased horse age at first race; having had a previous SDFT injury; and racing in the summer compared to other seasons. Variables found to be associated with decreased odds included: being trained by a more successful trainer; and having raced more frequently in the preceding 9–12 months. Conclusions: This study identified multiple risk factors associated with SDF tendinopathy, some of which are difficult to explain with the current data source. Factors resulting in increased cumulative horse and tendon fatigue (increased years in racing; carrying increased weight; and racing over longer distances), firm ground, and the presence of previous tendon injury should be considered when attempting to reduce the likelihood of sustaining SDF tendinopathy. Potential relevance: The results will facilitate the development of strategies to improve the overall safety of horses in hurdle racing in the UK.  相似文献   

Efficiency of Two Enucleation Methods Connected to Handmade Cloning to Produce Transgenic Porcine Embryos     

J Li  K Villemoes  Y Zhang  Y Du  PM Kragh  S Purup  Q Xue  AM Pedersen  AL Jørgensen  JE Jakobsen  L Bolund  H Yang  G Vajta 《Reproduction in domestic animals》2009,44(1):122-127

The purpose of our work was to establish an efficient-oriented enucleation method to produce transgenic embryos with handmade cloning (HMC). After 41–42 h oocytes maturation, the oocytes were further cultured with or without 0.4 μg/ml demecolcine for 45 min [chemically assisted handmade enucleation (CAHE) group vs polar body (PB) oriented handmade enucleation (OHE) group respectively]. After removal of the cumulus cells and partial digestion of the zona pellucida, oocytes with visible extrusion cones and/or polar bodies attached to the surface were subjected to oriented bisection. Putative cytoplasts without extrusion cones or PB were selected as recipients. Two cytoplasts were electrofused with one transgenic fibroblasts expressing green fluorescent protein (GFP), while non-transgenic fibroblasts were used as controls. Reconstructed embryos were cultured in Well of Wells (WOWs) with porcine zygote medium 3 (PZM-3) after activation. Cleavage and blastocyst rates were registered on day 2 and day 7 of in vitro culture respectively. Meanwhile, the total blastocyst cell number was counted on day 7. We found that the difference was only observed between blastocyst rates (38.6 ± 2% vs 48.1 ± 3%) of cloned embryos with GFP transgenic fibroblast cells after CAHE vs OHE. With adjusted time-lapse for zonae-free cloned embryos cultured in WOWs with PZM-3, it was obvious that in vitro developmental competence after CAHE was compromised when compared with the OHE method. OHE enucleation method seems to be a potential superior alternative method used for somatic cell nuclear transfer (SCNT) with transgenic fibroblast cells.  相似文献