THE ORIGIN AND DEVELOPMENT OF CLAY-WITH-FLINTS AND ASSOCIATED SOIL HORIZONS ON THE SOUTH DOWNS

Clay-with-flints rests on remnants of the exhumed sub-Eocene surface, which is shown to be an important geomorphological feature of the West Sussex Downs. Mineralogical and other soil profile studies indicate that the deposit has developed by the action of cryoturbation and soil-forming processes on a thin cover of Reading Beds clay left on the sub-Eocene surface during the southward recession of a small Eocene escarpment. Two horizons corresponding to Clay-with-flints sensu stricto of Loveday (1962) are recognized. The basal horizon is composed partly of insoluble Chalk residue, but mainly of clay moved down from overlying horizons into the spaces left on dissolution of the Chalk at the junction of the Chalk with the base of the Clay-with-flints. The upper horizon is composed of material from weathered remnants of Reading Beds clay, thoroughly mixed by cryoturbation with flints, other insoluble Chalk residue and clay from former basal horizons. The surface horizons of the soils often include additions of loess.     

The long-term effects of a range of pasture treatments applied to three semi-natural hill grassland communities.

Five pasture treatments were applied to three semi-natural hill grassland communities. The pasture treatments were: (1) controlled grazing, (2) controlled grazing + lime, (3) controlled grazing + lime + phosphate, (4) controlled grazing + lime + phosphate + oversown white clover and (5) controlled grazing + lime + phosphate + oversown white clover + oversown perennial ryegrass. The communities were dominated by Agrostis/Festuca (site 1), Molinia (site 2) and Nardus (site 3). The Nardus at site 3 was substantially reduced by herbicide before treatments were applied. All treatments were grazed simultaneously by mature wether sheep on three occasions each year to a residual herbage mass of 560 kg DM ha^?1. There were two grazing periods, each of 4 weeks duration, beginning in mid-May and mid-July respectively and a further grazing period of 3 weeks duration beginning in mid-October. The number of sheep grazing days and liveweight gain of sheep were recorded during each grazing period for 13 years at each site. Organic matter intake (OMI) and digestibility (OMD) of ingested herbage were measured in years 2, 5 and 13. Mean daily OMI per head ranged from 1290 g for treatment 1 to over 1400 g for treatments 4 and 5. OMI values were higher for the Agrostis/Festuca site (mean OMI 1450 g) than for the Molinia and Nardus sites (1310 g and 1370 g respectively) largely owing to differences in the values for treatments 1, 2 and 3. OMI values for each treatment decreased by around 300 g between May and October. Mean OMD values from treatments 1, 2 and 3 were higher for the Agrostis/Festuca site (0·66) than for the Molinia and Nardus sites (0·63 and 0·64 respectively). The OMD values for treatments 1, 2 and 3 at the Molinia and Nardus sites declined by between 0·05 and 0·02 between years 2 and 13 and also showed the greatest decrease between May and October (0·08). OMD values for treatments 4 and 5 (0·67 and 0·69 respectively) were higher than for treatments 1, 2 and 3 at all sites and levels were maintained over 13 years. Individual liveweight gains of sheep increased from treatment 1 (?18 g d^?1) to treatment 5 (82 g d^?1), but they decreased over time on all treatments. The Agrostis/Festuca site gave 17% more annual sheep grazing days than the Molinia site and 33% more than the Nardus site. The mean number of annual sheep grazing days for each treatment ranged from 2250 for treatment 1 to 3640 for treatment 5. Annual sheep grazing days increased over 13 years by between 35 and 45% for treatment 1 and 55 and 70% for treatment 5. The results are described in relation to the changes in pasture composition and herbage accumulation.     

Cardiovascular Effects of 1.0, 1.5, and 2.0 Minimum Alveolar Concentrations of Isoflurane in Experimentally Induced Hypothyroidism in Dogs

This study was performed to determine the cardiovascular responses to isoflurane in euthyroid and hypothyroid dogs. Four healthy mixed-breed dogs were studied prior to thyroidectomy (PRE), 6 months after thyroidectomy (HYP), and after 2 months of oral supplementation with 1-thyroxine (SUP). Heart rate (HR), cardiac output (), stroke volume (SV), systolic, diastolic, mean arterial blood pressure (SAP, DAP, MAP), and total peripheral resistance (TPR) were determined in awake dogs and in the same dogs when end-tidal isoflurane concentrations were 1.28%, 1.92%, and 2.56%. Ventilation was controlled in anesthetized dogs and Paco₂ maintained between 38 to 42 mm Hg. Isoflurane caused significant ( P <.05) dose-dependent reduction in , SV, SAP, DAP, and MAP in the PRE, HYP, and SUP dogs. Cardiac output was lower in the HYP dogs than in the PRE or SUP dogs during awake measurement. TPR was increased in the awake HYP dogs compared with the PRE or SUP dogs. During anesthesia, HYP dogs tended to have lower , SV, SAP, and MAP than the PRE or SUP groups, but the only significant reduction was SAP during 1.5 MAC. The cardiovascular responses to isoflurane in hypothyroid dogs are similar to euthyroid animals with a dose-dependent depression in , SV, and arterial pressure.     

Characterisation of porcine haemophili isolated from Australian pigs between 1988 and 1992

SUMMARY A total of 362 haemophili, isolated from pigs throughout Australia, were characterised by phenotypic properties. Most were identified as Actinobacillus pleuropneumoniae (296 isolates) or Haemophilus parasuis (52 isolates). The remaining isolates were identified as Haemophilus Taxon ‘minor group’ (12 isolates) and Haemophilus Taxon D (two isolates). All 296 A pleuropneumoniae isolates were serotyped by slide agglutination and/or gel diffusion, using rabbit antisera against all 12 recognised serovars. Of these, only 156 (52.7%) could be assigned to a single serovar as follows: serovar 1–85 isolates, serovar 2–4 isolates, serovar 3–2 isolates, serovar 5–10 isolates, serovar 7–51 isolates, serovar 11–2 isolates and serovar 12–2 isolates. Of the remaining 140 isolates, 91 gave cross-reactions with serovars 3 and 6, one cross-reacted with serovars 9 and 10, one cross-reacted with serovars 9 and 11 whereas 47 gave no reaction with any of the antisera.     

Presence of Maedi Visna Virus (MVV)‐Proviral DNA in the Genital Tissues of Naturally Infected Ewes

Maedi Visna virus (MVV) causes progressive degenerative inflammatory disease in multiple organs including the lungs (pneumonia, ‘maedi’), mammary gland, joints and nervous system (meningoencephalomyelitis, ‘visna’) in sheep. Maedi Visna Virus has been detected in macrophages of several tissues and epithelial cells in vivo: bone marrow, cells of the central nervous system, lung and bronchial tissues, milk epithelial cells recovered from milk samples and epithelial cells of mammary tissue. However, the presence of MVV in the genital tracts of naturally infected ewes has not previously been studied. The aim of this study was to use nested‐PCR, targeting the gag gene, to determine whether genital tissues (ovaries, oviducts and uterus) from 83 ewes originating from various breeding herds in the South‐East of France were positive for MVV‐proviral DNA. Peripheral blood mononuclear cells (PBMC) tested positive for MVV‐proviral DNA, using nested‐PCR analysis, in 57.8% of ewes (48/83). The provirus was also identified in 47% (78/166) of the ovaries, 38.6% (64/166) of the oviducts and 45.8% (38/83) of the uteri sampled. These findings clearly demonstrate, for the first time, that tissue samples from the genital tract of ewes (ovary, oviduct and uterus) can be infected with MVV. This suggests that there is a risk of vertical and/or horizontal transmission of MVV during embryo transfer from embryos produced in vivo or in vitro.     

Measurement of Parity Nonconservation and an Anapole Moment in Cesium

The amplitude of the parity-nonconserving transition between the 6S and 7S states of cesium was precisely measured with the use of a spin-polarized atomic beam. This measurement gives Im(E1pnc)/beta = -1.5935(56) millivolts per centimeter and provides an improved test of the standard model at low energy, including a value for the S parameter of -1.3(3)exp (11)theory. The nuclear spin-dependent contribution was 0.077(11) millivolts per centimeter; this contribution is a manifestation of parity violation in atomic nuclei and is a measurement of the long-sought anapole moment.     

Comparison of Membrane‐Permeant Fluorescent Probes for Sperm Viability Assessment in the Ram

This study was designed to compare the effectiveness and usability of four permeant fluorochromes (CFDA; SYBR‐14; Hoechst‐33342; and acridine orange), combined with propidium iodide to assess sperm membrane integrity. Three different experiments were conducted. The first trial was designed to study the optimal dye concentration and minimum incubation time required to achieve optimum fluorescence intensities and contrast for each fluorochrome combination using ram fresh semen samples. Both SYBR‐14 and acridine orange allowed a direct assessment of sperm membrane integrity, without the need of incubating samples, whereas a minimum of 4 and 6 min of incubation at 37°C was necessary to achieve optimum fluorescence intensities in the CFDA and Hoechst groups, respectively. In the second trial, fresh semen samples were mixed with different volumes of membrane‐affected sperm (semen treated with three cycles of freezing to ?20°C and thawing at room temperature) to produce semen samples with known proportions of damaged spermatozoa. The results were compared with the theoretical values predicted on the basis of the estimations made on fresh and frozen samples. The proportions of damaged sperm in each sample determined using the four fluorochrome combinations agreed with the predicted theoretical values, with the acridine orange/propidium iodide providing the best adjustment. The third experiment was performed to compare the results of sperm membrane integrity using the four fluorochrome combinations. The proportions of plasmalemma‐intact sperm determined by acridine orange and SYBR‐14 were greater (p < 0.0001) than the proportions of intact sperm determined by CFDA and Hoechst stains. It was concluded that the most efficient combinations to be used in ram sperm were AO/PI and SYBR/PI because it allowed a direct assessment of sperm viability without the need to incubate samples and obtaining reliable results.