Development of colchicine‐induced tetraploid St. Augustinegrass (Stenotaphrum secundatum) lines     

Esdras M. Carbajal  M. Carolina Zuleta  Luellen Swayzer  Brian M. Schwartz  Maria Carolina Chavarro  A. Carolina Ballen‐Taborda  Susana R. Milla‐Lewis 《Plant Breeding》2019,138(6):958-966

St. Augustinegrass is well suited for lawns and commercial landscapes. While many genotypes are cross‐fertile, all cultivars are propagated vegetatively in sod production. To ensure varietal purity, development of sterile triploid hybrids by crossing tetraploid and diploid genotypes has been successfully used in other warm‐season turfgrasses. Applying this model in St. Augustinegrass would be beneficial to sod producers and turf managers who require purity for certification and uniformity for performance, respectively. This study was conducted to develop colchicine‐induced tetraploid lines of St. Augustinegrass. Seeds of cultivar ‘Raleigh’ were treated with four colchicine concentrations at four exposure times. A non‐treated control was included among the treatments. Seedlings that germinated were screened for genome size changes using flow cytometry. Line DSA 13005 and two progeny lines derived through selfing, DSA 16001 and DSA 16016, were corroborated as tetraploids (2n = 4x = 36) through chromosome counts. These lines will be used in future breeding efforts to attempt development of sterile triploid cultivars of St. Augustinegrass.  相似文献   

Fate of Escherichia coli and Escherichia coli O157 in soils and drainage water following cattle slurry application at 3 sites in southern Scotland     

A.J.A. Vinten  D.R. Lewis  D.R. Fenlon  K.A. Leach  R. Howard  I. Svoboda  I. Ogden 《Soil Use and Management》2002,18(3):223-231

Abstract. Slurry from farm animals may contaminate water supplies, rivers and bathing waters with faecal coliforms, such as Escherichia coli . Where animals harbour the O157 strain the hazard to human health is particularly high, but both the hazard level, and the low incidence and sporadic nature of the excretion of E. coli O157 make it difficult to study this strain under field conditions. The survival of total E. coli and of E. coli O157 were compared in the laboratory for two soils under controlled temperature and moisture. E. coli O157 die-off rate was the same as or quicker than for total E. coli . This result meant that field experiments studying the fate of total E. coli should give a satisfactory evaluation of the risk of water contamination by the O157 strain. In four field experiments at three sites, slurry containing total E. coli numbers of 2.2 × 10⁴ to 5.7 × 10⁵ colony forming units per mL (c.f.u. mL^–1) was applied to drained field plots. Field die-off was faster than expected from laboratory experiments, especially in one experiment where two weeks dry weather followed application. In all but this experiment, the first drain flow events after slurry application led to very high E. coli concentrations in the drains (10³ to 10⁴ c.f.u. mL^–1). E. coli O157 was present in the slurry used for two of the experiments (33 c.f.u. per 100 mL in each case). However the proportion of E.coli O157 was very low (about 1 in 10⁵) and it was not detected in the drainage water. After the first week E. coli drainage water numbers decreased rapidly but they were 1–10 c.f.u. mL^–1 for much of the sampling period after slurry application (1–3 months).  相似文献   

Effects of timing and size of daylength change on brown egg laying domestic hens: Plasma luteinising hormone concentration and sexual maturity     

P. D. Lewis  G. C. Perry  T. R. Morris  B. K. Follett 《British poultry science》1994,35(1):25-31

1. Brown egg laying pullets were transferred from an 8‐h photoperiod to an 8‐, 10‐, 13‐ or 16‐h photoperiod at 6, 9, 12, 15, 18 or 20–3 weeks of age. Plasma luteinising hormone (LH) concentrations were measured at transfer and 7 and 14 d afterwards.

2. Significant increases in plasma LH occurred following light stimulations at 6, 9 and 12 weeks of age.

3. Changes in LH concentration 7 d after a light increase from 8 h to 8, 10, 13, 16 h were highly correlated with photoperiod length at 9 and 12 weeks of age.

4. Changes in LH were generally poorly correlated with age at sexual maturity, although the reduced influence on age at first egg of a light increase given close to sexual maturity was reflected in minimal LH responses at 18 and 20.3 weeks.  相似文献   

An economic evaluation of the differences between intensive and extensive beef production systems     

J M Lewis  T J Klopfenstein  G A Pfeiffer  R A Stock 《Journal of animal science》1990,68(8):2506-2516

A model to evaluate economic criteria involved when cattle are raised on high-forage diets prior to finishing or finished directly after weaning was developed using data from two experiments. In Exp. 1, each year for 3 yr, 136 Charolais-cross calves were weaned and allotted to either an intensive system, in which they were immediately finished on a high-grain diet, or an extensive system, in which they were wintered on crop residues, grazed on summer pasture and finished on a high-grain diet. In Exp. 2, 160 British breed steers were wintered, in one of eight different wintering systems utilizing crop residues, using supplemental protein and(or) alfalfa hay. After wintering, the steers grazed summer pasture and then were finished on a high-grain diet. Overall cost of gain and final "break-even" price were lower for cattle finished through the extensive system except when the price of corn was very low in relationship to other inputs. Interest costs were higher for cattle in the extensive system. Increasing the feeder calf purchase price had almost no effect on differences between the systems. Corn price and purchase price affected both systems similarly, whereas interest rate, wintering yardage and finishing yardage affected each system differently. Because of the additional weight produced through the extensive system, it yielded lower final "break-even" prices in most situations.  相似文献   

Ehlers-Danlos syndrome in a dog          下载免费PDF全文

Matthews BR  Lewis GT 《The Canadian veterinary journal. La revue veterinaire canadienne》1990,31(5):389-390

  相似文献   

Inhibition of DNA polymerase β activity in isolated bovine liver nuclei by captan and related compounds     

Jack W. Dillwith  Roger A. Lewis 《Pesticide biochemistry and physiology》1980,14(2):208-216

The effects on DNA synthesis of the fungicide captan and several structurally related compounds were investigated in isolated bovine liver nuclei. Captan, folpet, captafol, and trichloromethanesulfenyl chloride inhibited DNA synthesis to the same degree with ID₅₀ values of approximately 50 μM in a 40-min assay. The inhibition is concentration dependent and the degree of inhibition increases with time. Studies with structural analogs of captan indicated that inhibition of DNA synthesis by captan is mediated through the trichloromethylthio moiety of the captan molecule. In addition, the data indicate thiophosgene is probably not the toxic species involved in the inhibition of DNA synthesis. The isolated nuclei used in this study were shown to exhibit only a single DNA polymerase activity which was determined to be of the β or low-molecular-weight type. In addition to its inhibition in intact nuclei, captan inhibited the activity of the β polymerase in nuclear extracts as well as in partially purified enzyme preparations. These results indicate that captan inhibits DNA synthesis in our preparation of isolated nuclei by acting directly on the DNA polymerase-catalyzed reaction rather than by causing a nonspecific or indirect effect in the nuclear system such as alterations in the nuclear membrane or aggregation of the nuclei. The site of captan's inhibitory action is the DNA polymerase molecule. The interaction of captan with the polymerase results in irreversible inhibition of the enzyme. Interaction of captan with the template, if it occurs, does not appear to be involved in mediating the inhibition.  相似文献   

High-throughput real-time RT-PCR assay to detect the exotic Newcastle Disease Virus during the California 2002--2003 outbreak.   总被引：4，自引：0，他引：4  

Beate M Crossley  Sharon K Hietala  Liu-Mei Shih  Lou Lee  Evan W Skowronski  Alex A Ardans 《Journal of veterinary diagnostic investigation》2005,17(2):124-132

  相似文献   

Field use of isoflurane and air anesthetic equipment in wildlife.     

John C M Lewis 《Journal of zoo and wildlife medicine》2004,35(3):303-311

Conventional inhalation anesthesia of wildlife species within natural habitats presents significant practical problems. Heavy cylinders of medical grade oxygen are often unavailable in field situations. Equipment has been modified to permit the delivery of isoflurane in ambient air as the carrier and to be fitted with circuitry adaptable for different species and anesthetic situations. Preliminary empirical studies at low altitude in a range of small mammalian and avian species demonstrate the suitability of this combination and these techniques for inducing and maintaining anesthesia in clinically normal patients undergoing relatively minor procedures. The equipment has also been used to deepen and prolong anesthesia in several larger species, including great apes and large cats, after induction with injectable agents. These techniques, in combination with pulse oximetry to detect hypoxemia, provide a cheap, robust, and portable inhalation anesthetic system for field situations that is not dependent on compressed gasses.  相似文献   

Clinical characteristics of non-infectious inflammatory myopathy in the boxer dog     

H. P. Hong  S. A. Thomovsky  M. J. Lewis  R. T. Bentley  G. D. Shelton 《The Journal of small animal practice》2021,62(9):765-774

  相似文献   

Diagnostic accuracy of optical coherence tomography for assessing surgical margins of canine soft tissue sarcomas in observers of different specialties     

Josephine A. Dornbusch  Laura E. Selmic  Pin‐Chieh Huang  Jonathan P. Samuelson  Eric M. McLaughlin  Vincent A. Wavreille  Jessica A. Ogden  Brittany Abrams  Alex Kalamaras  Eric Green  Eric T. Hostnik  Lincoln Every  Jason A. Fuerst  Ryan Jennings  Christopher Premanandan  Joshua N. Lorbach  Sarah C. Linn  Aneesh Alex  Janet E. Sorrells  Lingxiao Yang  Stephen A. Boppart 《Veterinary surgery : VS》2021,50(1):111-120

  相似文献