Decreased common scab incidence after foliar sprays of daminozide

Summary In four small trials in two fields infested withStreptomyces scabies, potato foliage (cv. Maris Piper) was sprayed with solutions of the growth retardant daminozide in May–June. The sprays roughly halved the amount of scab in one field but were less effective in the other. The decrease in scab was not influenced by changes in daminozide concentration (3–10 g litre), by varying the timing of single sprays (mainly in June) or by spraying more than once. Yields of tubers were unaffected.     

Fructokinase,Fructans, Intestinal Permeability,and Metabolic Syndrome: An Equine Connection?

Fructose is a simple sugar present in honey and fruits, but can also exist as a polymer (fructans) in pasture grasses. Mammals are unable to metabolize fructans, but certain gram-positive bacteria contain fructanases and can convert fructans to fructose in the gut. Recent studies suggest that fructose generated from bacteria or directly obtained from the diet can induce both increased intestinal permeability and features of metabolic syndrome, especially the development of insulin resistance. The development of insulin resistance is driven in part by the metabolism of fructose by fructokinase C in the liver, which results in oxidative stress in the hepatocyte. Similarly, the metabolism of fructose in the small bowel by intestinal fructokinase may lead to increased intestinal permeability and endotoxemia. Although speculative, these observations raise the possibility that the mechanism by which fructans induce laminitis could involve intestinal and hepatic fructokinase. Further studies are indicated to determine the role of fructanases, fructose, and fructokinase in equine metabolic syndrome and laminitis.     

RAPD-based assessment of genetic relationships among and within American ginseng (Panax quinquefolius L.) populations and their implications for a future conservation strategy

American ginseng (Panax quinquefolius) is a native North American medicinal plant that is becoming increasingly vulnerable despite government harvest restrictions. To better understand the genetic diversity and gene flow of American ginseng, we studied RAPD variation in cultivated and wild populations. Classical and Bayesian analogues of genetic diversity statistics were estimated in seven wild and two cultivated populations. The wild populations were more highly structured (G _stβ  = 0.41) than the cultivated populations (G _stβ  = 0.24). The genetic diversity within populations ranged from H _eβ  = 0.05 to 0.38. Based on genetic pairwise distances, six of the wild populations clustered with the locally-derived cultivated population, while one wild population was more similar to the non-local cultivated population than the local populations. This wild population was highly diverse (P = 1.0; U = 1.0) suggesting that it was supplemented from exotic seed. A set of eight RAPD markers was identified that differentiated plants of local and non-local origin. As a conservation strategy, we recommend that regional gene banks be established based on molecular and geographic diversity to preserve the locally adapted germplasm. These regional gene banks would serve as a conservation tool and also provide a source of genes for genetic improvement of cultivated ginseng.     

Genetic relationship between the adult plant resistance gene Lr12 and the complementary gene Lr31 for seedling resistance to leaf rust in common wheat

A resistant phenotype similar to that conferred in wheat by the complementary genes Lr27  +  Lr31 was produced in the progeny of intercrosses of cultivars carrying Lr27 and a line possessing Lr12 . This confirms that Lr12 is either completely linked with Lr31 or is the same gene. On the basis of these findings and that Lr31 is located on chromosome 4BS, it is concluded that Lr12 must also be located on 4BS. Adult-plant genetic tests confirm that the Australian wheat cultivar Timgalen carries Lr12 , and stocks with Lr12 alone were established from this cultivar.     

Generation of Paramoeba perurans clonal cultures using flow cytometry and confirmation of virulence

Amoebic gill disease (AGD) in farmed Atlantic salmon is caused by the amoeba Paramoeba perurans. The recent establishment of in vitro culture techniques for P. perurans has provided a valuable tool for studying the parasite in detail. In this study, flow cytometry was used to generate clonal cultures from single‐sorted amoeba, and these were used to successfully establish AGD in experimental Atlantic salmon. The clonal cultures displayed differences in virulence, based on gill scores. The P. perurans load on gills, determined by qPCR analysis, showed a positive relationship with gill score, and with clonal virulence, indicating that the ability of amoebae to proliferate and/or remain attached on gills may play a role in virulence. Gill scores based on gross signs and histopathological analysis were in agreement. No association between level of gill score and specific gill arch was observed. It was found that for fish with lower gill scores based on histopathological examination, gross examination and qPCR analysis of gills from the same fish were less successful in detecting lesions and amoebae, respectively.     

Field trials of chemicals for control of common scab by soil treatment

Summary In six field trials, sixteen chemicals were compared against common scab, with quintozene as standard, by application to soil before planting. Captafol was as effective as quintozene, and did not decrease yield, but the closely related chemicals captan and folpet were ineffective. The other chemicals, of which over half were dihydroxybenzenes or dithiocarbamates, also failed to decrease scab. or decreased yield, or both.     

Porcine circovirus-2 DNA concentration distinguishes wasting from nonwasting pigs and is correlated with lesion distribution, severity, and nucleocapsid staining intensity.

The emergence of severe porcine circoviral disease in North America is associated with Porcine circovirus-2 genotype b (PCV-2b), which has led to speculation that PCV-2b is more virulent than PCV-2a. The objectives of this study were to 1) correlate the PCV-2 DNA concentration and lesions in wasting (WST) and age-matched healthy (HLTH) pigs from 2 clinically affected farms, and unaffected (UNFCT) pigs from a farm with no prior clinical or diagnostic history of PCVD; and 2) to determine the initial estimates of sensitivity and specificity of PCV-2 quantitative polymerase chain reaction (qPCR). PCV-2b was confirmed in all 3 farms. Compared with HLTH pigs, WST pigs demonstrated significantly more prevalent thymic atrophy, failure of normal pulmonary collapse, and ascites (P < 0.017 for all). The HLTH and UNFCT pigs had significantly more pronounced lymphoid germinal centers and proliferative paracortical T-dependent zones, compared with WST pigs (P < 0.017). Across all tissues, PCV-2 DNA concentrations were significantly higher in WST compared with HLTH and UNFCT pigs (P < 0.017 for all). The PCV-2 DNA concentrations were strongly correlated with PCV-2 nucleocapsid staining intensity in lymph node, spleen, Peyer's patches, lung, liver, and kidney (0.60 < or = r < or = 0.84). In the current study, the PCV-2 DNA log10 cutoff concentrations best able to distinguish WST from HLTH and UNFCT pigs were between 7.0 and 8.0 per gram for tissues, and between 4.0 and 5.0 per milliliter for sera. The presence of PCV-2b in UNFCT pigs is evidence that PCV-2b by itself is not sufficient to induce severe disease.