Vaccination against foot-and-mouth disease: the implications for Canada

Vaccination of susceptible animals against foot-and-mouth disease (FMD) is a well established strategy for helping to combat the disease. Traditionally, FMD vaccine has been used to control a disease incursion in countries where the disease has been endemic rather than in countries considered free of the disease. In 2001, the use of vaccine was considered but not implemented in the United Kingdom (1), whereas vaccine was used to help to control FMD in The Netherlands (2,3). Canadian contingency plans provide for the use of vaccine; Canada is a member of the North American Foot-and-Mouth Disease Vaccine Bank, which could supply vaccine if needed. This article explains why Canada might use FMD vaccine to combat an outbreak and the factors that are relevant to the disposal of vaccinated animals and their products. It concludes that vaccination is an important mechanism in Canada's preparedness for an outbreak of FMD and that products from vaccinated animals are safe for human consumption.     

Managing lead exposure and toxicity in cow-calf herds to minimize the potential for food residues.

Lead poisoning is commonly diagnosed in cattle. In this study, 3 groups of cattle from different herds accidentally exposed to discarded lead batteries on pasture were intensively studied to determine the extent and severity of exposure. The losses from acute death due to lead toxicity were substantial in all the 3 study groups at 12%, 17%, and 4%. Blood samples were taken from all cattle around the time of the first diagnosis and then later in 2 of the 3 herds to monitor the change in lead concentrations over time. Asymptomatic lead toxicosis was observed in these herds. In these 3 groups, between 4% and 12% of asymptomatic cattle had blood lead concentrations consistent with acute lead poisoning (> 0.35 ppm), and between 7% and 40% of these asymptomatic animals were in the high-normal range (0.1-0.35 ppm). Because of the consistently high number of asymptomatic cattle with elevated lead levels, all cattle potentially exposed to a lead source should be tested before sale or slaughter to minimize the entry of lead into the food chain. The blood lead concentrations, which were monitored for months after the initial diagnosis, decreased slowly after the cattle were removed from the lead source. The prolonged retention of lead may be due to continued release and absorption of lead from metal particles in the reticulum or rumen. The mean reduction in the lead level was 0.046 ppm (95% CI, 0.017-0.075 ppm) every 30 days for these 2 herds. Using a single-component exponential model, the half-life of lead in the animals retested from Herds 1 and 2 was highly variable. The median half-life was 63 days (interquartile range, 34-107 days). One out of 8 pregnant heifers with high blood levels had a stillborn calf. There were no abortions or calf mortalities in this group. Blood samples were'collected from the calves around the time of birth. The concentrations of lead in the blood of the calves exposed in utero were low (0.010-0.095 ppm).     

Evaluation of soybean germplasm conserved in NIAS genebank and development of mini core collections

Genetic variation and population structure among 1603 soybean accessions, consisted of 832 Japanese landraces, 109 old and 57 recent Japanese varieties, 341 landrace from 16 Asian countries and 264 wild soybean accessions, were characterized using 191 SNP markers. Although gene diversity of Japanese soybean germplasm was slight lower than that of exotic soybean germplasm, population differentiation and clustering analyses indicated clear genetic differentiation among Japanese cultivated soybeans, exotic cultivated soybeans and wild soybeans. Nine hundred ninety eight Japanese accessions were separated to a certain extent into groups corresponding to their agro-morphologic characteristics such as photosensitivity and seed characteristics rather than their geographical origin. Based on the assessment of the SNP markers and several agro-morphologic traits, accessions that retain gene diversity of the whole collection were selected to develop several soybean sets of different sizes using an heuristic approach; a minimum of 12 accessions can represent the observed gene diversity; a mini-core collection of 96 accession can represent a major proportion of both geographic origin and agro-morphologic trait variation. These selected sets of germplasm will provide an effective platform for enhancing soybean diversity studies and assist in finding novel traits for crop improvement.     

Detection of Colletotrichum coccodes from soil and potato tubers by conventional and quantitative real-time PCR

Colletotrichum coccodes is the causal agent of the potato blemish disease black dot. Two PCR primer sets were designed to sequences of the ribosomal internal transcribed spacer (ITS1 and ITS2) regions for use in a nested PCR. The genus-specific outer primers (Cc1F1/Cc2R1) were designed to regions common to Colletotrichum spp., and the species-specific nested primers (Cc1NF1/Cc2NR1) were designed to sequences unique to C . coccodes . The primer sets amplified single products of 447 bp (Cc1F1/Cc2R1) and 349 bp (Cc1NF1/Cc2NR1) with DNA extracted from 33 European and North American isolates of C. coccodes. The specificity of primers Cc1NF1/Cc2NR1 was confirmed by the absence of amplified product with DNA of other species representing the six phylogenetic groups of the genus Colletotrichum and 46 other eukaryotic and prokaryotic plant pathogenic species. A rapid procedure for the direct extraction of DNA from soil and potato tubers was used to verify the PCR assay for detecting C. coccodes in environmental samples. The limit of sensitivity of PCR for the specific detection of C. coccodes when inoculum was added to soils was 3·0 spores per g, or the equivalent of 0·06 microsclerotia per g soil, the lowest level of inoculum tested. Colletotrichum coccodes was also detected by PCR in naturally infested soil and from both potato peel and peel extract from infected and apparently healthy tubers. Specific primers and a TaqMan fluorogenic probe were designed to perform quantitative real-time (TaqMan) PCR to obtain the same levels of sensitivity for detection of C. coccodes in soil and tubers during a first-round PCR as with conventional nested PCR and gel electrophoresis. This rapid and quantitative PCR diagnostic assay allows an accurate estimation of tuber and soil contamination by C. coccodes .     

Anthropogenic influences on potential fire spread in a pyrogenic ecosystem of Florida, USA

Fire has historically been an important ecological factor maintaining southeastern U.S. vegetation. Humans have altered natural fire regimes by fragmenting fuels, introducing exotic species, and suppressing fires. Little is known about how these alterations specifically affect spatial fire extent and pattern. We applied historic (1920 and 1943) and current (1990) GIS fuels maps and the FARSITE fire spread model to quantify the differences between historic and current fire spread distributions. We held all fire modeling variables (wind speed and direction, cloud cover, precipitation, humidity, air temperature, fuel moistures, ignition source and location) constant with exception of the fuel models representing different time periods. Model simulations suggest that fires during the early 1900's burned freely across the landscape, while current fires are much smaller, restricted by anthropogenic influences. Fire extent declined linearly with patch density, and there was a quadratic relationship between fire extent and percent landscape covered by anthropogenic features. We found that as little as 10 percent anthropogenic landcover caused a 50 percent decline in fire extent. Most landscapes (conservation or non-conservation areas) are now influenced by anthropogenic features which disrupt spatial fire behavior disproportionately to their actual size. These results suggest that land managers using fire to restore or maintain natural ecosystem function in pyrogenic systems will have to compensate for anthropogenic influences in their burn planning. This revised version was published online in May 2005 with corrections to the Cover Date. This revised version was published online in July 2006 with corrections to the Cover Date.     

Germination and seedling growth of <Emphasis Type="Italic">Dimorphandra jorgei</Emphasis> MF Silva and <Emphasis Type="Italic">Swartzia macrostachya</Emphasis> Benth. var. <Emphasis Type="Italic">riedelii</Emphasis> Cowan

Dimorphandra jorgei MF Silva (Caesalpinaceae) and Swartzia macrostachya Benth. var. riedelii Cowan (Fabaceae) are tree species from the southern Bahian Atlantic Forest, identified for the restoration of degraded areas. The objective of this research is to study their seed germination and seedling growth to develop simple methods for seedling production in small scale nurseries. Because the species have distinct dormancy and germination characteristics, the seeds were submitted to different treatments. D. jorgei seeds were immersed in hot water, scarified and stored for 12 weeks in the laboratory environment (25°C). S. macrostachya seeds were submitted to different combinations of drying and storage in the laboratory environment or refrigerator (4°C). Seedlings were submitted to two light treatments for 3 months: partial shade (52% of full sun) and full shade (12% of full sun). In D. jorgei, the highest germination occurred for scarified seeds (87%) and for seeds stored for 12 weeks and then scarified (69%). In S. macrostachya the undried control seeds had the highest germination, followed by that of the refrigeration storage treatment, without predrying (99% and 97%, respectively). The average values for the growth parameters were greater in full shade for D. jorgei, while S. macrostachya seedlings showed greater growth rates in partial shade. Two months growth is recommended before D. jorgei seedlings are of the sufficient size and leaf number for field planting. On the other hand, a period of 4 months is recommended for S. macrostachya, due to its relatively slow growth.     

Genetic Diversity of the Vigna Germplasm from Thailand and Neighboring Regions Revealed by AFLP Analysis

Thailand is a center of diversity for section Angulares of the Asian Vigna (genus Vigna subgenus Ceratotropis) and 4 Vigna species are cultivated in Thailand. Using newly collected wild and cultivated germplasm of Vigna from Thailand and outgroup accessions AFLP analysis was conducted to clarify genetic diversity and relationships. The results suggest that cultivated V. umbellata and V. mungo evolved from wild relatives in a single domestication event. Vigna umbellata is poorly differentiated from its wild and weedy relatives compared to V. mungo. Results suggest northern Thailand and the neighboring Shan state, Myanmar, is the probable center of domestication for V. umbellata as wild accessions from this area and cultivated rice bean from a wide area in Asia are not greatly diverged. Vigna minima, V. tenuicaulis and V. exilis accessions in Thailand are well differentiated with considerable intra-specific variation. Vigna hirtella consists of two well differentiated subgroups, suggesting taxonomic revision may be necessary. Close genetic relationships between V. radiata and V. grandiflora, and between V. mungo and V. trinervia are confirmed. Naturally growing V. mungo populations in northern Thailand appear to be true wild species as they are well differentiated from Indian wild and Thai cultivated populations. The origin of naturally growing cowpea in Thailand needs to be further studied using a more comprehensive set of materials. This study clarifies inter and intra-specific genetic diversity and inter species relationships of Thai Vigna species.     

Evaluation of a Midhumeral Block of the Radial,Ulnar, Musculocutaneous and Median (RUMM Block) Nerves for Analgesia of the Distal Aspect of the Thoracic Limb in Dogs

Objective: To evaluate a technique for midhumeral peripheral nerve blockade in the dog. Study Design: Cadaveric technique development; in vivo placebo‐controlled, prospective crossover study. Animals: Canine cadavers (n=38) and 8 clinically healthy, adult hound dogs. Methods: A technique for peripheral block of the radial, ulnar, musculocutaneous, and median nerves (RUMM block) was evaluated using cadaver limbs. Eight purpose‐bred, research dogs were anesthetized; a RUMM block was performed on each thoracic limb. One limb from each dog randomly received 0.5% bupivacaine and the opposite limb was assigned to receive sterile saline solution as a control. After recovery from anesthesia, skin sensation at selected dermatomes was evaluated for 24 hours using a mechanical stimulus. Weight‐bearing, conscious proprioception, and withdrawal reflex were also evaluated. One month after initial testing, each dog was reanesthetized and each limb received the opposite treatment. Results: Sensory thresholds were significantly increased over baseline measurements when compared with control limbs for all nerves. Complete sensory block was achieved in radial (15/16), ulnar (3/16), musculocutaneous (8/16), and median (11/16) nerves, using a mechanical stimulus of analgesia. Complete simultaneous block of all nerves was only obtained in 1 of 16 limbs. Conclusion: RUMM block resulted in desensitization of the skin in the associated dermatomes for 4–10 hours. Complete sensory block of the dermatomes supplied by the radial nerve was most consistent. Clinical Relevance: RUMM block may be an effective technique to provide adjunctive analgesia for dogs undergoing surgery of the distal aspect of the thoracic limb.     

XY male pseudohermaphroditism in a captive Arabian oryx (Oryx leucoryx).

A 2-yr-old Arabian oryx (Oryx leucoryx) was presented for evaluation of abnormal genitalia and infantile behavior. The oryx had a penis and a scrotum, but testes were not palpable within the scrotum or inguinal canal. The total serum testosterone for the individual was lower than in age-matched males of the same species. Surgical exploration showed markedly hypoplastic intra-abdominal gonads, which demonstrated both testicular and uterine tissue on histologic examination. After karyotype analysis, the individual was classified as an XY male pseudohermaphrodite. This condition resembles two human intersex syndromes: embryonic testicular regression syndrome and partial gonadal dysgenesis syndrome, which occur in familial lines.     

Salmonella pullorum in the common pheasant (Phasianus colchicus)

In 1996, pullorum disease due to Salmonella enterica serovar Gallinarum biovar pullorum (Salmonella pullorum) was diagnosed in pheasants on a gamebird rearing enterprise in south-west Scotland. The gross pathology and bacteriological findings are described, as are the results of screening for S pullorum on the site in 1997. The causal organism was readily isolated from the lung, liver, yolk sac and heart blood on direct culture, but less readily from the digestive tract or by the use of selective media. The bacteria recovered from the pheasants were identified as S pullorum phage type 7, a phage type previously associated with pheasants rather than domestic fowl, and the organisms were most probably introduced to the site by the movement of carrier pheasants.