Localized origins of herbicide resistance in Alopecurus myosuroides

The process of evolution of resistance to acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicides was investigated in four distinct patches of Alopecurus myosuroides Huds. (black-grass) that occur within adjacent fields on a cereal farm in Nottinghamshire, UK. In one field, there was a `main' patch containing 96% resistant plants and two `satellite' patches containing ≈2.9% and 4.4% resistant plants, and in an adjacent field another patch contained 25% resistant plants. Genome fingerprinting by simple sequence repeat (SSR)-anchored polymerase chain reaction (PCR) was used to analyse variation at 30 genetic loci in at least 20 resistant and 20 sensitive individual plants from each patch, from additional resistant populations from Essex and Lincolnshire, and from a sensitive reference population. Banding patterns were found to be highly repeatable. Each patch contained a high level of genetic diversity, regardless of its resistance status, and there was evidence for genetic differences between the patches (Gst = 0.14, Nei's distances up to 0.26). There was no evidence that resistance had spread from the `main' patch to the others, as resistant and sensitive plants in the same patch were more closely related on average than were resistant plants from neighbouring patches. The most likely explanations of this distribution, and their implications, are discussed.     

The survival of Alopecurus myosuroides Huds. seeds in soil

The survival of Alopecurus myosuroides seeds was studied in soil under arable cropping and short term grass leys in which seed return was prevented. At two winter wheat sites, where weed seeds were sown, the mean annual seed decline was 73–83% over a 2- or 3-year period. The rate of decline was similar with all the cultivation systems studied: ploughing, tine cultivation and direct drilling. Seeds buried initially by ploughing, and then not disturbed by cultivation, were slightly more persistent. At five arable sites with natural populations of A. myosuroides, seed numbers declined to an average of 3% of the original amount present after 3 years, and to 1% after 4 years. Initial populations of over 50 000 seeds m^?2 were recorded. Plant populations were not always proportional to the total seed content of the soil, especially on ploughed land. Seed decline in two grass fields was similar to that under arable cropping. A. myosuroides plants were recorded in a wheat crop following a 2-year grass ley. Weed plants did not persist in the vegetative state in grass used for conservation and grazing. At all sites, appreciable quantities of seeds were still present in the soil after 2–4 years. Although a relatively small proportion of seeds survived, the actual number of seeds surviving was substantial. For this reason, it was concluded that any eradication policy is unlikely to be effective in a cropping system dominated by winter cereals.     

Inscribing Workplaces: The Spatiality of the Production Process

ABSTRACT In this paper, the social being in the spatiality of the production process is addressed. Spatiality, following Soja (1989), means the ceaseless and recursive dialectical interplay amongst time, space, and the social being. The production process, as a specific set of social relations, comprises both the tasks associated with productive labor and the regulations that organize the extraction of surplus value. The social being as worker is located within the various sets of power relations in the workplace, and workers as social beings position themselves within and amongst the numerous sets of social relations that are part of the production process. Distributions of power are negotiated through labor and mediated by other sets of social relations in specific places as well as the historical and material conditions of the lives of individual workers and their employment at a firm. This conceptual argument is demonstrated by drawing on information gathered in multiple-depth interviews with women employed as franchise housekeepers, personal experience as a franchise housekeeper, and structured interviews with managers, owners, and head office personnel in housekeeping services franchises.     

Isolation of Clostridium novyi (Cl. oedematiens) from liver lesions in a dog with pancreatic acinar carcinoma

This paper records the isolation of Clostridium novyi from liver lesions in a dog with pancreatic acinar carcinoma and multiple hepatic metastases.     

Adsorption and bioactivity of di-allate,tri-allate and trifluralin*

Studies were conducled to cstmiate the adsorption parameter k and the bioactivity (in terms of G R₅₀) of di-allate [S-2,3-dichloroallyl N, N-di-isopropyl (thiocar bamate)], iri-allate [S-2,3,3-trichloroallyl N, N -di-isopropyl (thiocar bamate], and [trifiuralin (2,6-dinitro N, N-dlpropyl-4-trifluoromelhylaniline) in a number of Saskatchewan soil. The k values ratiged from 5 for di-allate adsorption m Asquilh loamy sand to 315 for trifluralin adsorption on Melfort loam and were closely related to the soil organic matter content. The relative degree of adsorption was irifluralin > tri-allate >di-allaie. For each herbicide, the G R₅₀ values were positively correlated wich organic matter conienl atid wilh k. It was suggested that these nonionic herbicides may be amenable to a predictive approach for field application rates in different soils. Among herbicides for any one soil, however, there was not the same relationship between G R₅₀andk. since the G R₅₀ was least for trifluralin and there was no significant difference between di-allate and tri-allate.     

Surgical Stabilization of the Equine Cervical Spine

The Cloward technique for intervertebral fusion was utilized on 12 horses ranging from 3 months to 2 years of age. Of the 12 horses, 9 had been diagnosed as having equine cervical vertebral malformation (CVM) or "wobbles," and 3 were normal controls. A large hole was drilled from the ventral border of the vertebral bodies spanning the intervertebral disc and the vertebral end plates of the 2 articulating vertebrae. Frozen homologous bone dowels of slightly larger diameter from equine cadaver ilia were inserted in the holes. No adverse postoperative complication arose. Clinical improvement was seen in all horses with CVM. Three months postoperatively, partial or complete fusion was evident radiographically in 11 of the 12 horses. Necropsies were performed 3–6 months postoperatively to evaluate the quality of the fusion. Cadaver manipulation demonstrated reduced intervertebral movement at the operative site in all cases. The articulations of the equine cervical spine can be operatively fused by the Cloward technique, and surgically induced trauma is minimal. This technique can be used for stabilizing subluxations and may be applicable for treating fractures and osteolytic processes that have weakened vertebrae.