The effect of xylazine on plasma thromboxane B2 concentration in sheep

α₂-adrenoceptor agonist drugs can cause respiratory changes leading to a short period of hypoxaemia in sheep. It has been suggested that this is due to transient platelet aggregation and pulmonary microembolism. If platelet aggregation were to follow platelet activation in response to the administration of α₂ agonists, plasma thromboxane levels would be expected to rise. This study was carried out to measure plasma thromboxane B₂ concentrations before and after the intravenous administration of the α₂-agonist drug xylazine at a dose of 0.1 mg/kg. It was found that the plasma thromboxane concentration rose by 320% and, furthermore, the rise was prevented by the prior administration of atipamezole hydrochloride (0.125 mg/kg), an α₂-adrenoceptor antagonist.     

Persistent haematuria in a dog due to a discrete renal haemangioma

Persistent haematuria had been observed for 5 months in a 9-year-old male Collie. Investigation, including intravenous pyleography and selective arteriography, led to the presumptive diagnosis of a discrete left renal mass. The dog made an uneventful recovery after left nephrectomy. Histologically the lesion proved to be a medullary and pelvic haemangioma.     

OIL BIOREMEDIATION IN SALT MARSH MESOCOSMS AS INFLUENCED BY N AND P FERTILIZATION,FLOODING, AND SEASON

Bioremediation of crude oil in salt marsh mesocosms growing Spartina alterniflora was investigated during winter and summer to determine the influence of nitrogen (N) and phosphorus (P) fertilization, flooding, and season. Fertilization with urea and ammonium (NH₄ ⁺) applied at 75 or 150 kg N ha^-1 with or without P did not significantly (p = 0.05) increase oil or hydrocarbon degradation in continuously flooded mesocosms over an 82 day period during winter (temperature range of 17 to 30 °C). Phosphorus applied at 40 kg P ha^-1 significantly (p = 0.05) increased oil and hydrocarbon degradation. Nitrate (NO₃ ^-) added alone did not increase oil or hydrocarbon degradation, but when added with P, it significantly (p = 0.05) increased degradation above that for P alone. Up to 70% of applied oil and 75% of applied hydrocarbons were degraded in P supplemented treatments. Inipol, an oleophilic fertilizer containing N, P, and a dispersant, significantly increased oil and hydrocarbon degradation. During a 40 day summer experiment (temperature range of 27–42 °C), N and P fertilization did not increase oil or hydrocarbon degradation. For continuously flooded treatments, 72% of applied hydrocarbons were degraded while 51% were degraded in alternately flooded treatments. Mesocosms provided conditions suitable for quantitative recovery of oil and results indicated that N and P fertilization, flooding, and season interacted to influence oil bioremediation. Even under the most favorable conditions, more than 1 month was required for most of the oil to disappear.     

Interaction of a bioherbicide and glyphosate for controlling hemp sesbania in glyphosate-resistant soybean

The bioherbicidal fungus, Colletotrichum truncatum (Schwein.) Andrus & Moore, was tested at different inoculum concentrations alone and in combination with, prior to or following treatment with different rates of glyphosate ( N -[phosphonomethyl]glycine) (Roundup Ultra) for the control of hemp sesbania ( Sesbania exaltata [Raf.] Rydb. ex A.W. Hill) in Roundup Ready soybean field plots. Colletotrichum truncatum and glyphosate were applied in all pair-wise combinations of 0, 1.25, 2.5, 5.0, and 10.0 × 10⁶ spores mL⁻¹ (i.e. 3.125, 6.25, 12.5, and 25 × 10¹¹ spores ha⁻¹), and 0.15, 0.30, 0.60, and 1.2 kg ha⁻¹, respectively. Weed control and disease incidence were enhanced at the two lowest fungal and herbicidal rates when the fungal spores were applied after glyphosate treatment. The application of the fungus in combination with or prior to glyphosate application at 0.30 kg ha⁻¹ resulted in reduced disease incidence and weed control regardless of the inoculum's concentration. At the highest glyphosate rates, the weeds were controlled by the herbicide alone. These results suggest that it might be possible to utilize additive or synergistic herbicide and pathogen interactions to enhance hemp sesbania control.     

Redvine (Brunnichia ovata) and trumpetcreeper (Campsis radicans) controlled under field conditions by a synergistic interaction of the bioherbicide, Myrothecium verrucaria, with glyphosate

In field experiments conducted near Stoneville, MS, USA, in 2000 and 2001, the bioherbicidal fungus, Myrothecium verrucaria (Alb. & Schwein.) Ditmar: Fr., was tested alone and in combination with a glyphosate ( N -[phosphonomethyl]glycine) product for controlling natural infestations of the invasive vines, redvine ( Brunnichia ovata [Walt.] Shinners) and trumpetcreeper ( Campsis radicans [L.] Seem. ex Bureau). After 12 days, redvine and trumpetcreeper were controlled by 88% and 90%, respectively, through a synergistic interaction between the fungus and the herbicide, glyphosate. The disease symptomatology was characterized by rapid necrosis of the leaf and stem tissues, with mortality occurring within 72 h. Neither glyphosate alone, nor M. verrucaria alone, controlled these weeds at commercially acceptable levels (≥80%). No visual disease or herbicide damage occurred to the soybean in the treated test plots 12 days after planting. These results suggest that some formulations of glyphosate, mixed with M. verrucaria , can effectively control redvine and trumpetcreeper.     

Dynamics of competition between wild oats (Avena fatua L.) and winter cereals

This study examined the effects of competition on the growth of Avena fatua, winter wheat and winter barley. Plants were sampled at frequent intervals from replacement series experiments at two contrasting sites in the U.K. A. fatua was much slower to establish than the two cereals, but thereafter exhibited a faster rate of growth. In monoculture, it took a considerable time for A. fatua to reach a size equal to that of the cereals, but by the end of the experiments it was the largest of the three species. The change-over from cereal dominance in mixtures to A. fatua tiominance was rapid, and in three cases coincided with cereal flag leaf emergence. In the fourth case, it appeared to coincide with the art of canopy height extension. At one site the rder of competitiveness at anthesis was A. fatua= barley>wheat, and at the other site the order was A. fatua>wheat>barley. In order to explain and predict differences between years and sites, more studies are required on morphological development in relation to abiotic variables.     

In vitro Maturation of Oocytes from Santa Ines Ewes Subjected to Consecutive Sessions of Follicular Aspiration by Laparoscopy

The success of embryo production in vitro depends upon the use of an efficient oocyte retrieval technique, and the best results have been obtained by laparoscopic aspiration. The aim of this study was to evaluate the effect of consecutive sessions of follicular aspiration on the quantity, quality and in vitro maturation competence of oocytes obtained from ewes subjected to hormonal stimulation. Six Santa Ines ewes underwent nine sessions of follicular aspiration by laparoscopy with a 7‐day interval between sessions, totalling 56 aspirations. After 24 h of culture, oocytes were stained and classified according to the stage of nuclear and cytoplasmic maturation. Oocyte retrieval rate was 61.4 ± 2%, resulting in a total of 249 oocytes. No significant variation was observed between sessions (p > 0.05). The average number of oocytes retrieved from each ewe was 6.4 ± 2 per session and 42 ± 4 in total. No significant difference was observed between the frequencies of the different stages of nuclear maturation: 32.72% mature, 40.74% immature and 26.54% degenerated/indeterminate oocytes; however, a significant difference was observed between the frequencies of the different stages of cytoplasmic maturation: 10.7% mature, 73.25% immature and 16.05% degenerated/indeterminate oocytes. No significant difference was observed in nuclear or cytoplasmic maturation between the weeks of procedure. We conclude that after nine consecutive sessions of follicular aspiration, the quantity and quality of retrieved oocytes remained unchanged as well as the levels of nuclear and cytoplasmic maturation obtained, demonstrating the viability of this technique for repetitive follicular aspirations on the same donor.