Evaluation of PCR,IEF and ELISA techniques for the detection and identification of potato cyst nematodes from field soil samples in England and Wales

Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4–6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given. © 2001 Society of Chemical Industry     

氯虫苯甲酰胺和氟虫双酰胺对不同虫态甜菜夜蛾的毒力作用

采用浸叶法、点滴法、夹毒叶片法、成虫药膜法、饲喂毒营养液法测定了氯虫苯甲酰胺、氟虫双酰胺对甜菜夜蛾卵、2~4龄幼虫、成虫的活性和对4龄幼虫的拒食活性,以明确氯虫苯甲酰胺和氟虫双酰胺对不同虫态甜菜夜蛾的毒力作用。结果表明,两种杀虫剂均不具有杀卵活性,但可以明显降低初孵幼虫存活率;氯虫苯甲酰胺、氟虫双酰胺均对2龄幼虫活性最高,分别为3龄幼虫的1.50、6.17倍和4龄幼虫的22.25、44.95倍,对4龄幼虫胃毒活性分别为触杀活性的14.10、8.44倍;氯虫苯甲酰胺对甜菜夜蛾成虫毒力为氟虫双酰胺的25.53~34.19倍。氯虫苯甲酰胺、氟虫双酰胺对甜菜夜蛾幼虫表现出较强的拒食作用, 至处理后48 h拒食率达到最高, 分别为 82.73%、84.15%,显著高于对照药剂甲维盐各浓度处理,处理试虫虫体皱缩、体节缩短,体重增加率明显低于对照和甲维盐各处理。     

Characterization of cereal bare patch isolates of Rhizoctonia solani by random amplified polymorphic DNA analysis

RAPD-PCR was used to characterize isolates of Rhizoctonia solani from bare patches in cereal and pasture crops at two locations in Western Australia, Newdegate and Esperance. All of the isolates belonged to anastomosis group 8, pectic zymogram group 1-1 or 2. The pectic zymogram assignment could be confirmed by RAPD-PCR. There was no difference in RAPD-PCR pattern between highly virulent and weakly virulent isolates at Newdegate, or between isolates from different patches at Newdegate. The Newdegate isolates were identical to isolates from Esperance, and to isolates from various locations in South Australia.     

Influence de la fertilisation azotée sur la receptivityéďun sol au piétin-échaudage,le développement de la maladie au champ et les populations de Pseudomonas fluorescents1

Différents travaux montrent que le piétin-échaudage est moins grave quand le blé reçoit une fertilisation azotée sous forme ammoniacale plutôt que sous forme nitrique. Les hypothèses avancées pour expliquer ce phénomène sont une réduction du pH de la rhizosphère, ayant un effet direct sur le développement du champignon, ou indirect par stimulation ?une partie de la microflore, ou encore une incidence de la forme ?azote sur la physiologie de la plante. Dans un essai conduit au champ, trois modalités expérimentales ont été combinées: cultivars, traitement fongicide de semences, fertilisation azotée. Les résultats présentés ici portent sur ce dernier facteur à deux niveaux (sulfate ?ammonium ou ammonitrate). Deux notations, à partir de plantes prélevées au champ, ont renseigné sur ?évolution du piétin-échaudage: seule la fertilisation azotée a eu un effet signiflcatif sur le développement de la maladie, le sulfate ?ammonium réduisant de moitié la fréquence de plantes attaquées (15 contre 32%), sans diminuer la gravité des attaques. Parallèlement, des tests réalisés sur échantillons de sols prélevés en décembre, mars et mai, ont indiqué qu'à ces trois périodes les sols fertilisés avec du sulfate ?ammonium étaient moins réceptifs que ceux fertilisés avec de ?ammonitrate. Enfin, les analyses sur une fraction bactérienne de la microflore ont montré que les Pseudomonas fluorescents étaient quatre fois plus nombreux pour le sulfate ?ammonium que pour ?ammonitrate.     

Ecdysial failures in the cotton boll weevil: Synergism of diflubenzuron with juvenile hormone

The frequency and etiology of ecdysial failures occurring during the pupal-adult transformation of the cotton boll weevil, Anthonomus grandis, was studied after treatment with juvenile hormone (JH) and/or diflubenzuron (DFB). Failure at emergence was the result of inability of the adult insects to escape from their pupal exuviae. Teratogenic effects in the form of pupal-adult intermediates or adults with pupal characters were not obtained with JH or DFB treatment after the larval-pupal ecdysis. Combining JH with the DFB treatment yielded a synergistic response that increased the frequency of ecdysial failures about sevenfold when applied in the later pupal stages. The fine structure of the abdominal cuticle of adults experiencing ecdysial failure after treatment with JH as white-eyed pupae exhibited granular deposits within the lamellar region and interference with deposition of the nonlamellate endocuticle. DFB treatment of the earlier pupal stages interfered with deposition of the lamellate cuticle by eliminating or reducing the lamellar structure. It was concluded that the primary interaction of JH with DFB was that of extending or reinitiating DFB sensitivity in the later pharate adult. A secondary interaction may involve inhibition of cuticle hardening as both JH and DFB appear to inhibit the tanning process of adults treated as white-eyed pupae.     

Build-up and subsequent decline of residues of quintozene and hexachlorobenzene in lettuce in sequential crops

The build-up and decline of quintozene and hexachlorobenzene residues in protected lettuce, resulting from one to five treatments of the soil (each of 35 g m-2) with a quintozene formulation, have been studied. Residue levels were monitored in each experimental crop during growth until harvest. Residues in the soil at harvest were also determined. Quintozene residues in the harvested lettuce were in the range < 0.02–0.80 mg kg^?1 and those of hexachlorobenzene were in the range < 0.02–0.05 mg kg^?1 (expressed on a fresh weight basis). Residue levels in the soil were 5.4–231 mg kg^?1 for quintozene, and 0.20–5.4 mg kg^?1 for hexachlorobenzene (expressed on a dry weight basis). Under the experimental conditions of the trial there was no significant build-up of quintozene or hexachlorobenzene in harvested lettuce, even after five treatments to the same site.     

关于新疆1∶100万农业地貌区划问题的讨论

根据新疆同一地貌区域形态成因，水热及农业发展方向和改造利用条件的相似性或不同地貌区间的差异性原则，建立起构造、新构造运动、外力作用，地貌形态等农业区划樗，以及农业地貌各级区域标志。     

Report of the 3rd Havemeyer workshop on allergic diseases of the Horse, Hólar, Iceland, June 2007

Allergic diseases occur in most mammals, although some species such as humans, dogs and horses seem to be more prone to develop allergies than others. In horses, insect bite hypersensitivity (IBH), an allergic dermatitis caused by bites of midges, and recurrent airway obstruction (RAO), a hyperreactivity to stable born dust and allergens, are the two most prevalent allergic diseases. Allergic diseases involve the interaction of three major factors: (i) genetic constitution, (ii) exposure to allergens, and (iii) a dysregulation of the immune response determined by (i) and (ii). However, other environmental factors such as infectious diseases, contact with endotoxin and degree of infestation with endoparasites have been shown to influence the prevalence of allergic diseases in humans. How these factors may impact upon allergic disease in the horse is unknown at this time. The 3rd workshop on Allergic Diseases of the Horse, with major sponsorship from the Havemeyer Foundation, was held in Hólar, Iceland, in June 2007 and focussed on immunological and genetic aspects of IBH and RAO. This particular venue was chosen because of the prevalence of IBH in exported Icelandic horses. The incidence of IBH is significantly different between Icelandic horses born in Europe or North America and those born in Iceland and exported as adults. Although the genetic factors and allergens are the same, exported adult horses show a greater incidence of IBH. This suggests that environmental or epigenetic factors may contribute to this response. This report summarizes the present state of knowledge and summarizes important issues discussed at the workshop.     

Pharmacokinetics of morphine and its metabolites in freshwater rainbow trout (Oncorhynchus mykiss)

In this study, we injected morphine sulfate IP into rainbow trout and measured the concentration of morphine and all potential metabolites in plasma using LC-MS/MS at a series of times after the injection. The pharmacokinetics of morphine were similar to those previously reported for seawater-acclimated rainbow trout, i.e. they were about one order of magnitude slower than in similarly sized mammals. The only metabolite of morphine present in the plasma was morphine-3-β- d -glucuronide (M3G); morphine-6-β- d -glucuronide (M6G) was not detected. M3G gradually increased after the morphine injection, peaked about 2 days later, then gradually decreased. In mammals, M3G plasma levels exceed morphine levels extremely rapidly, i.e. in less than an hour, regardless of dose, route of administration, or species. In trout, it took 2 days for M3G levels to exceed morphine levels. This is the first study of the metabolites of morphine in any ectotherm. We conclude that trout can metabolize morphine, but at a rate much slower than in mammals.     

Adipose tissue gene expression in obese dogs after weight loss

Body weight (BW) mainly depends on a balance between fat storage (lipogenesis) and fat mobilization (lipolysis) in adipocytes. BW changes play a role in insulin resistance (IR), the inability of insulin target tissue to respond to physiological levels of insulin. This results in inhibition of lipogenesis and stimulation of lipolysis. Weight gain leads to IR whereas, weight loss improves insulin sensitivity (IS). The aim of this study was to evaluate the effect of weight loss and recovery of IS on the expression of genes involved in lipogenesis and lipolysis in weight losing dogs. Gene expression was studied in both subcutaneous and visceral adipose tissue. Obese dogs received a hypoenergetic low fat high protein diet (0.6 x NRC recommendation). Before and after weight loss, IS was assessed using the euglycaemic hyperinsulinaemic clamp. Gene expression of IRS-2, SREBP, intracellular insulin effectors, ACC, FAS, FABP, ADRP, PEPCK, lipogenesis key proteins, perilipin and HSL, lipolysis key proteins were quantified using real-time RT-PCR in subcutaneous and visceral fat. BW decreased from 15.2 +/- 0.5 to 11.4 +/- 0.4 kg (p < 0.05) over 78 +/- 8 days. When obese, dogs were insulin resistant. After weight loss, IS was improved. In the subcutaneous adipose tissue, the expression of only the IRS-2 was increased. In the visceral adipose tissue, the expression of the genes involved in the lipogenesis was decreased whereas one of the genes implied in the lipolysis did not change. The expression profile of genes involved in lipid metabolism, as measured after weight loss, is indicative for a lower lipogenesis after weight loss than in obese dogs. Our results also confirm dramatic differences in the lipid metabolism of visceral and subcutaneous fat. They should be completed by comparing gene expression during weight losing and normal weight steady state.