The effect of temperature on glutathione S-transferase activity and glutathione content in Alopecurus myosuroides (black grass) biotypes susceptible and resistant to herbicides

Herbicide‐resistant populations of Alopecurus myosuroides (black grass) have become widespread throughout the UK since the early 1980s. Previous observations in this laboratory have demonstrated that natural climatic fluctuations caused increases in endogenous glutathione S‐transferase (GST) enzyme activity in A. myosuroides plants as they mature, which is thought to be linked to herbicide resistance in this species. The present study has investigated the effects of plant growth at 10°C and 25°C, and reports GST specific activity and glutathione (GSH) pool size in resistant and susceptible A. myosuroides biotypes. Findings demonstrate differences in GST activity between resistant and susceptible populations, which are transient at lower growth temperatures. The GSH pool size was elevated at lower growth temperature in both biotypes. We speculate that these endogenous responses are part of a natural mechanism of acclimation to environmental change in this species and suggest that resistant plants are more able to adapt to environmental stress, as indicated in this instance by temperature change. These observations imply that the control of resistant A. myosuroides by graminicides may be more effective when applied at lower temperatures and at earlier growth stages.     

Retrospective study of 108 foals with septic osteomyelitis

Objective   To determine the clinical characteristics, short-term outcome and future athletic performance of foals with septic osteomyelitis.
Design   Retrospective clinical study of 108 Thoroughbred foals with radiographic evidence of bone infection that were presented at the Scone Veterinary Hospital between August 1995 and December 2001. Medical records were reviewed and information concerning signalment, the clinical, laboratory and radiographic findings, treatment and outcome was obtained. Racing records were obtained and evaluated for surviving foals that had reached racing age.
Results   Mean age of foals at initial evaluation was 39 days (range 1–180 days); 21 foals had multiple radiographic bone lesions (19.4%), and 76 had concurrent septic arthritis (70.4%). The most frequently affected bones were the femur, tibia and distal phalanx. In total, 87 foals were discharged from the hospital (80.6%), 79 survived long-term to reach racing age and 52 raced (65.8%). Overall, 48% (52/108) of the foals treated for osteomyelitis raced. Foals less than 30 days of age at the time of diagnosis, critically ill foals and those with multiple bones or joints affected were significantly less likely to be discharged from hospital. Multiple septic joints, but not multiple bone involvement, had an unfavourable prognosis for racing.
Conclusions   The prognosis for survival of foals with septic osteomyelitis or osteitis is favourable. Multiple bone or joint involvement is an important short-term prognostic indicator; however, the involvement of multiple joints, but not multiple infected bones, is associated with an unfavourable prognosis for racing.     

Salmonids and flows: a perspective on the state of the science and its application

Water flow, volume discharge per unit time, is a master variable influencing much of the river environment and having profound effects on most of the biota, either directly or indirectly. Nevertheless, after decades of research and much accumulated knowledge, there remains much uncertainty about how to set environmental standards for flows that protect ecosystem components, including salmonids. This paper provides an overview of the findings of a conference on Flows and Salmonids. The aim of the conference and the papers that form this special issue is to update this information for salmonids, from which four key points are distilled that might influence future direction. (1) Fish responses to flow are very variable and flow effects are highly confounded with other related variables, which are often the proximate factors and need to be taken into account. (2) Meta‐analysis of previous studies has yet to be achieved because a hydromorphological template against which to gather and display such data has not yet been satisfactorily defined. (3) Some deviation from natural conditions may not necessarily be as detrimental for salmonids as sometimes stated. (4) Local investigations of flow impacts and solutions based on local conditions, and bringing in diverse disciplines and stakeholders, appear to offer the most pragmatic and effective approach to defining and implementing protective flows. Adaptive management offers a route for such collaborative studies, and its use is strongly encouraged.     

Monochorial diamniotic dizygotic twins in a German Shepherd Dog: A case report

Case report: A 6.5‐year‐old clinically healthy German Shepherd Dog with regular oestrous cycles of 6 months was presented for pregnancy diagnosis on day 38 after ovulation (p.ov.). Ultrasonography revealed three individual placental sites in progressed resorption and two vital adequately developed foetuses sharing a joint placenta. On days 41 and 48 p.ov., sonographic signs indicated normal development of both foetuses, but on day 52 p.ov., both foetuses were found to be dead. A caesarean section was performed the same day. Examination of the removed uterus confirmed the diagnosis of a “twin” pregnancy with two foetuses sharing the same placental site but separate amniotic membranes. One foetus showed generalized oedema (anasarca). Bacterial culture of swabs taken from inside the placental cavity was negative. At histological examination of the uterus, no signs of inflammation were found. Serum relaxin concentrations (day 38, 41, 48 and 52. p.ov.) were consistent with those of bitches with normal pregnancies. Cytogenetic analysis of the two foetuses revealed dizygotic twins, one male and one female according to SRY‐PCR. By genotyping 17 high‐polymorphic canine microsatellites, it could be demonstrated that the two foetuses developed from two different oocytes.     

Evaluation of an ultrasonic Doppler probe for pregnancy diagnosis in cattle

SUMMARY The use of an ultrasonic Doppler probe for pregnancy diagnosis was evaluated. Data from the examination of 1115 cattle were analysed. Comparison of the probe with manual rectal palpation by an experienced clinician yielded a sensitivity of 92.8 ± 1.6% (± 95% confidence interval) and a specificity of 75.8 ± 7.4%. This level of accuracy was found to be insufficient to recommend the probe be used by farmers for the diagnosis of pregnancy.     

Identification of a nonpathogenic Erwinia amylovora guaB mutant

A nonpathogenic Erwinia amylovora transposon mutant that has an insertion in the gua B gene was isolated. The mutation results in a nutritional requirement for guanine or xanthine, and loss of ability to produce ooze on immature pear fruit and to cause symptoms in the apple seedling assay. The mutant expressed other known virulence determinants including extracellular polysaccharide and had an intact hrp/dsp cluster. In addition it was able to grow in host tissue, although the population size in planta was maintained at a considerably lower level than that seen with the parent strain. The inability of the Erwinia amylovora gua B mutant to cause disease indicates that levels of guanine in plant tissue are likely to be insufficient to maintain optimal growth via the purine salvage pathway. This, in turn, appears to compromise the ability of the mutant to develop a sufficiently large population size in planta to overcome host defence mechanisms and cause disease symptoms. This indicates that a functional de novo guanine synthetic pathway is important for Erwinia amylovora to grow on plant tissue and cause disease.     

Epidemiological studies of pig diseases: 2. Post-weaning diarrhoea and performance in Western Australian pigs

Objective To determine in Australian pig herds the accuracy of French protocols for risk factor assessment of post-weaning diarrhoea and illthrift.
Procedure French protocols for the collection of data on health indicators and risk factors for post-weaning diarrhoea were conducted on 54 batches of weaner pigs from 28 Western Australian pig herds during three years.
Results Large variations in post-weaning performance were found. About one-third of the batches were growing at <200 g/day during the 3 weeks after weaning, and 54% had growth rates of <250 g/day. Weaning age and weight of at least 30 days and 7.9 kg, respectively, optimised weaner performance. Other risk factors associated with little post-weaning diarrhoea and good weaner performance were high creep feed intakes, relatively little diarrhoea as suckers, and, contrary to expectations, large temperature fluctuations.
Conclusion Overall, the 'predictability' of post-weaning problems as assessed by measurement of risk status, was good. However, the model was less accurate at predicting the performance of a single batch of pigs.