Characterization and origin of infection of Rhizoctonia solani associated with Brassica oleracea crops in the UK

An extensive study was conducted to determine where in the production chain Rhizoctonia solani became associated with UK module-raised Brassica oleracea plants. In total, 2600 plants from 52 crops were sampled directly from propagators and repeat sampled from the field. Additional soil, compost and water samples were collected from propagation nurseries and screened using conventional agar isolation methods. No isolates of R. solani were recovered from any samples collected from propagation nurseries. Furthermore, nucleic acid preparations from samples of soil and compost from propagation nurseries gave negative results when tested for R. solani using real-time PCR. Conversely, R. solani was recovered from 116 of 1300 stem bases collected from field crops. All the data collected suggested R. solani became associated with B. oleracea in the field rather than during propagation. Parsimony and Bayesian phylogenetic studies of ribosomal DNA suggested the majority of further classified isolates belonged to anastomosis groups 2-1 (48/57) and AG-4HGII (8/57), groups known to be pathogenic on Brassica spp. in other countries. Many R. solani isolates were recovered from symptomless plant material and the possibilities for such an association are discussed.     

Development of a One-Step Real-Time Polymerase Chain Reaction Assay for Diagnosis of Phytophthora ramorum

ABSTRACT Phytophthora ramorum is a recently described pathogen causing bleeding cankers, dieback, and leaf blight on trees and shrubs in parts of Europe and North America, where the disease is commonly known as sudden oak death. This article describes the development of a single-round real-time polymerase chain reaction (PCR) assay based on TaqMan chemistry, designed within the internal transcribed spacer 1 region of the nuclear ribosomal (nr)RNA gene for detection of P. ramorum in plant material. Unlike previously described methods for the molecular detection of P. ramorum, this assay involves no post amplification steps or multiple rounds of PCR. The assay was found to have a limit of detection of 10 pg of P. ramorum DNA, and could detect P. ramorum in plant material containing 1% infected material by weight within 36 cycles of PCR. The assay also was used to test DNA from 28 other Phytophthora spp. to establish its specificity for P. ramorum. A quick and simple method was used to extract DNA directly from host plant material, and detection of P. ramorum was carried out in multiplex with an assay for a gene from the host plant in order to demonstrate whether amplifiable DNA had been extracted. Amplifiable DNA was extracted from 84.4% of samples, as demonstrated by amplification of host plant DNA. The real-time protocol was used to test 320 plant samples (from 19 different plant species) from which DNA extraction had been successful, and was shown to give results comparable with a traditional isolation technique for diagnosis of P. ramorum in plant material from common U.K. hosts.     

Seasonal patterns of cytokinins and microclimate and the mediation of gas exchange among canopy layers of mature Acer saccharum trees

Seasonal patterns of cytokinins (CKs) and microclimate were examined in the upper, middle and lower canopy layers of mature Acer saccharum Marsh. (sugar maple) trees to elucidate the potential role of CKs in the mediation of gas exchange. The upper canopy showed a distinctly dissimilar microclimate from the middle and lower canopy layers with higher photosynthetically active radiation and wind speed, but showed no corresponding differences in transpiration (E) or stomatal conductance (g(s)). Although E and g(s) tended to be higher in the upper canopy than in the middle and lower canopies, the differences were not significant, indicating regulation beyond the passive response to changes in microclimate. The upper canopy accumulated significantly higher concentrations of CKs, predominantly as ribosides, and all canopy layers showed distinct seasonal patterns in CK profiles. Multiple regression models showed significant relationships between both g(s) and E and foliar CK concentration, although these relationships varied among canopy layers. The relationships were strongest in the middle and lower canopy layers where there was less fluctuation in leaf water status and less variability in abiotic variables. The relationships between gas exchange parameters and leaf CK concentration began to decouple near the end of the growing season as foliar phytohormone concentrations changed with the approach of dormancy.     

A rapid onset, post-capture muscle necrosis in the Norway lobster, Nephrops norvegicus (L.) from the West coast of Scotland

A post-capture, abdominal muscle necrosis of rapid onset has been identified in Norway lobsters, Nephrops norvegicus (L.), captured off the West coast of Scotland. Economic losses, as a result of the mortality of these animals in transport, were encountered by Scottish wholesalers during the summer and autumn of 1999. Affected animals show a characteristic whitening of individual muscle fibres and fibre bundles of the abdomen within hours of capture, with a progression towards complete opacity of the abdominal musculature within a number of days. The pathology causes a loss of the normal function of the abdomen; thus, preventing the normal 'tail flip' swimming. Electron microscopy failed to reveal any obvious causative agent but showed that affected tissue displayed a progressive disruption of sarcomere organization, loss of Z-line material, condensation of myofibrils and infiltration of necrotic regions by granulocytes. SDS–PAGE of affected muscle tissue showed that there was a great reduction of most of the major contractile proteins. The condition most closely resembles idiopathic or spontaneous muscle necrosis, a pathology previously reported from both wild and cultured crustaceans. Damage to the integument in conjunction with exposure to various stressors during and immediately after capture is the most likely cause of the pathology. The rapid onset of the pathology has implications for the post-capture handling procedure for N. norvegicus and their subsequent vivier transport to market. It may also be partially responsible for the high mortality rate of undersized N. norvegicus returned to the sea after capture and aerial emersion.     

Angling for endangered fish: conservation problem or conservation action?

Recreational angling has been implicated in population declines of some marine and freshwater fish, but this activity is rarely considered as a threat or even halted when endangered species are targeted. Indeed, in some cases, anglers are drawn to fish for rare or endangered species. Conservation‐oriented behaviours such as catch‐and‐release are often practiced voluntarily due to the ethics of anglers, yet even in these cases, some fishing mortality occurs. Nonetheless, there are many indirect conservation benefits associated with recreational angling. Here, we present a series of case‐studies and consider whether catch‐and‐release angling for endangered fish is a conservation problem or a conservation action. If recreational angling activities contribute to population‐level consequences that are contrary to recovery strategies, then angling for endangered species would seem to be a poor option. However, as revealed by several case‐studies, there is much evidence that anglers are vocal and effective proponents of fish and habitat conservation, and for endangered species, they are often the only voice when other stakeholders are not engaged. Anglers may contribute directly to conservation actions via user fees (e.g. licences), philanthropic donations or by volunteering in research, education and restoration activities. However, it is important to quantify post‐release mortality as well as understand the full suite of factors influencing a given population or species to know the potential risks. A risk assessment approach outlined in the paper may be used by managers to determine when the benefits of angling for endangered species outweigh the risks.     

Enhancement after feline immunodeficiency virus vaccination.

Cats were vaccinated with one of the three preparations: purified feline immunodeficiency virus (FIV) incorporated into immune stimulating complexes (ISCOMs), recombinant FIV p24 ISCOMs, or a fixed, inactivated cell vaccine in quil A. Cats inoculated with the FIV ISCOMs or the recombinant p24 ISCOMs developed high titres of antibodies against the core protein p24 but had no detectable antibodies against the env protein gp120 or virus neutralising antibodies. In contrast, all of the cats inoculated with the fixed, inactivated cell vaccine developed anti-env antibodies and four of five had detectable levels of neutralising antibody. However, none of the vaccinated cats were protected from infection after intraperitoneal challenge with 20 infectious units of FIV. Indeed there appeared to be enhancement of infection after vaccination as the vaccinated cats become viraemic sooner than the unvaccinated controls, and 100% of the vaccinated cats became viraemic compared with 78% of the controls. The mechanism responsible for this enhancement remains unknown.     

胚胎移植安格斯犊牛适应性研究

湖北省于 2 0 0 0年 5月和 11月分两批利用胚胎移植技术 (以地方黄牛为受体 )引进了新西兰安格斯肉牛品种。本项目对第 1批胚移所产犊牛在湖北的适应性进行了研究。这批胚移犊牛表现了较好的生长发育与良好的适应性。它们的平均出生重与 3月龄内的日增重分别为 33.7(母 )～ 37.6 (公 )kg和 0 .75 1(公 )～ 0 .75 6 (母 )kg。但也发现了犊牛培育上出现的某些问题 ,如生长速度不很高 ,有一定的发病率 (如腹泻、上呼吸道感染、贫血 )。研究认为 ,出现这些问题的原因主要有 :没有充分满足生长犊牛的营养需要 ,湖北襄阳的生态环境条件与引入地 (新西兰 )的差别 ,饲养方式上从放牧向舍饲的改变 ,兽医缺乏犊牛的临床经验等。建议应用胚胎移植技术引进牛品种和培育胚移犊牛时 ,应注意尽量选择杂交牛与个体较大、尻部 (骨盆腔 )发育好的母牛做受体 ,重视母牛科学饲养 ,喂好犊牛初乳 ,重视犊牛补饲 ,改善环境条件 ,加强卫生防疫与防病治病工作。     

The potential of small ruminant farming as a means of poverty alleviation in rural southern India

Small ruminant production has the potential to address the global challenge of greatly increased food production in impoverished rural areas in a manner that is socioeconomically sustainable and carbon efficient. Twenty-six small ruminant landless farmers in three villages in the Kanchipuram District of the state of Tamil Nadu were surveyed with regard to their sheep farming practice and production indices, with the preliminary aim of evaluating the potential of small ruminant farming in alleviating poverty in parts of rural in southern India. The small ruminant farmers reared mostly indigenous Madras Red sheep as a means of generating primary or supplementary income. Participatory interviews were undertaken to enable the completion of a questionnaire pertaining to sheep production over the four most recent annual production cycles (referred to as instances) at the time of the study. When calculating the annual farm profits without taking into consideration the opportunity cost of labour, 83% of annual sheep production cycles over a 4-year period added to household incomes. Further, 23% of the instances that accounted for the opportunity cost of labour, household income was raised above the Indian Government’s defined poverty line solely through small ruminant farming. Management practices were identified, while participating in landless farmer interviews provided an insight into the husbandry, or lack thereof, which resulted in low lambing percentages and rates of high ewe losses, perinatal lamb mortality and abortion. The study showed both the vulnerability and potential resilience of small ruminant farming to natural disaster, in this case catastrophic flooding in 2015. While small ruminant farming generated income in most instances, the way it is practiced creates opportunities for simple changes in husbandry and management that could make it more efficient in poverty alleviation.