A seismotectonic model for the 300-kilometer-long eastern tennessee seismic zone

Ten years of monitoring microearthquakes with a regional seismic network has revealed the presence of a well-defined, linear zone of seismic activity in eastern Tennessee. This zone produced the second highest release of seismic strain energy in the United States east of the Rocky Mountains during the last decade, when normalized by crustal area. The data indicate that seismicity produced by regional, intraplate stresses is now concentrating near the boundary between relatively strong and weak basement crustal blocks.     

Enzyme specificity as a factor in regulation of fatty acid chain length in Escherichia coli

Various acyl-acyl carrier protein intermediates in saturated and unsaturated fatty acid biosynthesis were tested as substrates for beta-ketoacyl-acyl carrier protein synthetase. With both classes of substrates the condensing enzyme in fatty biosynthesis demonstrates specificities which indicate that it might be an important factor in determining fatty acid chain length in Escherichia coli.     

Inoculation with Bartonella henselae followed by feline herpesvirus 1 fails to activate ocular toxoplasmosis in chronically infected cats

Infection by Toxoplasma gondii is very common in cats although most remain disease free. The factors that trigger development of uveitis in some cats infected with T gondii have not been elucidated, but infection by more than one organism may be contributory. In this study, cats chronically infected with T gondii were inoculated with Bartonella henselae followed by FHV-1 to test the hypothesis that immune stimulation by multiple infections will reactivate ocular toxoplasmosis. Anterior uveitis and chorioretinitis were not detected in the cats with chronic T gondii infection thus allowing rejection of the hypothesis using this experimental design.     

Remnant genetic diversity detected in an ancient crop: Triticum dicoccon Schrank landraces from Asturias, Spain

Emmer wheat, Triticum dicoccon Schrank was one of the founder crops of Neolithic agriculture. Though its cultivation was largely replaced by hexaploid wheats 2000 years ago, pockets of small scale cultivation can still be found. One such area is the Asturias region of Northern Spain, where emmer wheat remains a traditional crop for high value specialist culinary uses, and farmers grow locally adapted landraces. In order to study the diversity of these landraces, we sampled emmer wheat from different regions of Asturias, and genotyped multiple plants from each village using nuclear and chloroplast microsatellites. A high level of variation was observed with markers from both genomes, including a novel chloroplast haplotype. A strong geographic structure was observed in the Asturian emmer wheats in both the chloroplast markers and the nuclear microsatellite data.     

A graft-based chemotherapy method for screening effective molecules and rescuing huanglongbing-affected citrus plants

Huanglongbing (HLB) is the most devastating disease of citrus. The global citrus industry is in urgent need of effective chemical treatments for HLB control because of its rapid spreading worldwide. Due to the fastidious nature of the pathogens, and the poor permissibility of citrus leaf surfaces, effective screening of chemicals for the HLB control can be challenging. In this study, we developed a graft-based chemotherapy method to rapidly screen potential HLB-controlling chemical compounds. In addition, we improved transmission efficiency by using the best HLB-affected scion-rootstock combination, and demonstrated the HLB bacterial titer was the critical factor in transmission. The HLB-affected lemon scions had a high titer of HLB bacterium, survival rate (83.3%), and pathogen transmission rate (59.9%). Trifoliate, a widely used commercial rootstock, had the highest survival rate (>70.0%) compared with grapefruit (52.6%) and sour orange (50.4%). Using this method, we confirmed a mixture of penicillin and streptomycin was the most effective compounds in eliminating the HLB bacterium from the HLB-affected scions, and in successfully rescuing severely HLB-affected citrus germplasms. These findings are useful not only for chemical treatments but also for graft-based transmission studies in HLB and other Liberibacter diseases.     

Characteristics and comparative performance of direct culture, direct PCR and enumeration methods for detection and quantification of Campylobacter spp. in broiler caeca

Detection and enumeration of Campylobacter spp. in broiler chicken flocks are key components of research and surveillance studies aimed at reducing Campylobacter infections in people. Direct culture of caecal contents onto selective agar is the typical method used to confirm flock colonisation. Modified charcoal cefoperazone deoxycholate agar (mCCDA) is commonly used for this method, although alternative selective media have been used. Additionally, PCR methods to detect Campylobacter DNA from caecal contents may provide a rapid alternative. However comparative performance data for these methods is limited and therefore required to ensure optimal detection methods for this sample type. In this study, 306 broiler caeca were tested for Campylobacter using direct culture on mCCDA, Skirrows and Preston agars and two real-time PCR methods, one specific for mapA/ceuE regions and another for the flaA gene region. Additionally, the suitability of spread plating and spiral plating methods for enumeration of Campylobacter and the impact of sample storage were assessed. This study confirmed modified CCDA as an optimal media for detection of Campylobacter in broiler caeca. It was significantly more sensitive than Skirrows or Preston agars. This study also demonstrated that the mapA/ceuE PCR had excellent agreement with culture on mCCDA and is a genuine alternative method. Spread plating and spiral plating methods were suitable for enumeration although spiral plating appeared more sensitive for stored samples (72h). A 1 log reduction in viable Campylobacters was observed in stored samples, therefore storage effects should be considered for quantitative studies with broiler caeca.     

Low-field standing magnetic resonance imaging findings of the metacarpo/metatarsophalangeal joint of racing Thoroughbreds with lameness localised to the region: a retrospective study of 131 horses

Reasons for performing study: The metacarpo/metatarsophalangeal (MCP/MTP) joint is a common site of lameness in the Thoroughbred racehorse. Radiographs may fail to show pathology consistent with the degree of lameness. With a high incidence of stress fractures occurring in the distal third metacarpal/metatarsal (MC3/MT3) condyles and proximal phalanx, a definitive diagnosis as to the nature of the pathology is essential. Objective: To describe the low‐field magnetic resonance imaging (MRI) findings in Thoroughbred racehorses with MCP/MTP joint pain scanned under standing sedation. Methods: The MR images and clinical records of all Thoroughbred racehorses undergoing MRI of the MCP/MTP joint between October 2006 and August 2010 were reviewed. A total of 168 joints from 131 horses were selected for inclusion. The MRI finding considered most significant in the lame (or lamest) limb was noted. Results: Diagnostic quality images were obtainable in 97.8% of horses. The most common finding was palmar/plantar osteochondral disease in MC3/MT3 (54.9% of horses). Incomplete condylar fracture was diagnosed in 19.8% of horses, with the lateral condyle predominating. An incomplete sagittal fracure of P1 was diagnosed in 14.5% of horses and 11.4% were diagnosed with ‘dorsal joint disease’. Other findings included transverse MC3 stress fractures (1.5%), soft tissue injuries (12.2%) and proximal phalangeal ‘contusions’ (3.8%). No significant bone/soft tissue injury was detected in 5.4% of cases. Conclusions: Standing MRI can detect a spectrum of disease within the MCP/MTP joints of racehorses. The procedure is well tolerated and may lead to a definitive diagnosis where radiographic imaging is inconclusive. Potential relevance: A total of 35.8% of cases had MRI findings consistent with fracture pathology, which could not be confirmed radiographically at the time of the MRI examination. This has important therapeutic and prognostic implications and may help to prevent catastrophic injury.     

PEDOMETER MEASUREMENTS OF THE DISTANCE WALKED BY GRAZING SHEEP IN RELATION TO WEATHER

During the winter months of 1963 and 1964, mature non–pregnant Clun Forest ewes at pasture were equipped with pedometers to study the value of these instruments for measuring distances walked, and to investigate the importance of weather on the distances travelled. Approximately 80 periods were recorded, each of about 24 hours. The accuracy of the measurements was checked by using a rangemeter and it was found that the reliabihty of pedometer records must be assessed on the animal from which they are obtained. The individual characteristics of the pedometers and/or the sheep gave rise to inaccurate records from about 50% of the instruments studied.
Multiple regression analysis of data for each of the three sheep which provided suitable records revealed that, in dry weather, the average distance walked per hour of recording period increased signiJBcantly with mean air temperature in one case and with hours of bright sunshine in another. Wind–speed effects were unimportant. The distance walked by all three sheep increased significantly with hours of daylight per recording period, and this was the only variable found to affect distance walked in wet weather. Differences between average distances walked per hour under dry–and wet–conditions were non–significant.
It is concluded that for measuring the distances walked by sheep, the disadvantages of the pedometer outweigh its advantages.     

Technical and commercial aspects of biocontrol products

The global agrochemical market in 1991 was $26800 million, yet biological products were reported to account for only $120 million of sales per annum—less than 0.5 % of the total. The majority of these sales are attributed to bio-insecticides of which Bacillus thuringiensis accounts for over 90%, but B. thuringiensis could be described as a biologically produced insecticide, rather than a true biocontrol agent. Biological products have technical limitations, including extreme specificity, sensitivity to environmental factors and problems with robustness of the formulations, but ironically, it is these limitations which also give biological control an image of environmental acceptability. Nonetheless, some of the limitations will be overcome and sales will increase, but primarily in niche situations such as the control of soil-borne diseases and the control of insect pests showing resistance to agrochemicals. In order for significant inroads to be made into such niche markets it is imperative that progress with biological products is not impaired by over-regulation, and a rational approach by all regulatory bodies is required. Overall, though, agrochemicals are likely to continue to be the major method of crop protection for the foreseeable future, and the biological control field now needs clear, well-defined goals if current successful niche products can be the basis for future success rather than a limited experiment in alternative technology.