Field evaluation of the single intradermal cervical tuberculin test and the interferon-gamma assay for detection and eradication of bovine tuberculosis in Spain

A field comparison of the interferon-gamma (IFN-gamma) assay and the single intradermal cervical tuberculin (SICT) test for the diagnosis of bovine tuberculosis was conducted. A total of 1136 cattle belonging to 85 herds placed in 'Castilla y León' (northwestern Spain) were chosen, and 21 of these herds were subjected to the diagnostic assays two or three times at intervals of at least 4 months. All the animals positive to any of the tests were slaughtered and tuberculosis was confirmed by culture isolation method (CIM) and further identification by means of PCR. Only 10.6% of cattle reacted with the bovine PPD in the SICT test, a percentage that increased to 12.8% in the IFN-gamma assay. The sensitivity of the IFN-gamma assay compared to CIM was shown to be higher (84.9%) than that of the SICT test (80.2%), but the combination of both tests offered the highest sensitivity (92.9%). The number of false positive reactors (those animals in which CIM was negative) was considerably higher for the IFN-gamma assay than for the SICT test and, conversely, the number of false negative animals (M. bovis isolation but negative immunological result) was higher for the skin test than for the interferon assay. In the herds tested twice, tuberculosis was eradicated after the second cycle of testing in 50%, and in 75% after the third cycle in herds tested three times. The combination of these two techniques instead of separately seems, therefore, to be useful in eradication programmes against bovine tuberculosis.     

Recent developments in the epidemiology of virus diseases

There is continual variation in viral epidemics regarding clinical symptoms, duration and disappearance, and the emergence of new diseases. This can be observed in both human and animal diseases. This evolution of virus diseases is mainly related to three factors: aetiological agent, host and environment. As far as genetic alterations of the virus are concerned, two major mechanisms are involved: mutations such as recombination and reassortment; and selection for resistance or susceptibility. This review focuses on the epidemiology of newly emerged virus diseases in man and animals, such as acquired immunodeficiency syndrome, haemorraghic fevers, bovine spongiform encephalopathy, canine haemorraghic disease and respiratory syndrome in horses.     

A Universal `One-tube' RT-PCR Protocol for Amplifying Isolates of Bovine Viral Diarrhoea Virus

The increase in the knowledge of the genetic variability of BVDV and the identification of some of the genetic determinants of its pathogenicity require robust and practical tools for rapid molecular characterization of the various genotypes of this virus. This study was undertaken to develop a standard protocol for RT-PCR that allows the amplification of various parts of the genome of BVDV without the need for optimizing each individual reaction. The reaction set-up is very flexible because it consists of two pre-mixes. These are a master mix, with all the required reagents except the desired primers, which are the components of the second pre-mix and are therefore easily interchangeable between the different reactions. After adding any primer-containing pre-mix to the fixed master mix, a non-interrupted cycling protocol led to the generation of amplicons of up to 4 kbp in size in amounts sufficient for subsequent sequencing reactions. The method was applied to five different regions of the BVDV genome: (i) the well-known 5-UTR to differentiate genotypes I and II; (ii) the entire E2 gene, or an approximately 550 bp region within the E2 gene, in order to find the molecular equivalent of antigenic varieties; (iii) the entire structural protein coding region covering the Npro, capsid, E ^RNS, E1 and E2 genes; (iv) a 2.1 kbp region embracing the NS2/3 junction which is known to be cleaved in cytopathic biotypes of BVDV; and (v) the region covering the entire NS4B and NS5A/B genes. All six RT-PCRs were successfully applied using (i) primers with lengths of between 20 and 52 nucleotides, (ii) an aliquot of RNA extracted from either 10⁶ infected bovine embryonal lung cells or the same number of leukocytes from viraemic cattle, and (iii) all the genotype I and II strains of BVDV tested. The technique described was used to generate various Sindbis virus/BVDV recombinants. The correct processing of the amplicon-derived E2 glycoprotein of BVDV strain PT810 was demonstrated by its reaction with a monoclonal antibody in an immunofluorescence assay. Given the variety of RT-PCRs tested, we conclude that this universal protocol may be useful with other RNA viruses.     

6种保护剂单独使用或混合使用对3种鞘翅目害虫的防治效果

通过实验室试验以确定某些粮食保护剂混合使用时是否有增效或拮抗作用。６种粮食保护剂被单独或混合使用防治储藏玉米和小麦中的谷蠹，储藏小麦中的米象和赤拟谷盗。使用了４种有机磷杀虫剂（杀螟松、甲基毒死蜱、虫螨磷、丁烯硫磷），１种保幼激素（蒙五一五）和１种增效除虫菊酯（除虫菊酯＋增效醚）；混合处理时用蒙五一五或增效除虫菊酯加１种有机磷杀虫剂。根据对成虫后代的防治水平和防治时间看，这些保护剂之间没有拮抗反应。结果表明为了避免药剂的拮抗作用或者取得增效作用，不需改变实仓施药时的使用比例。混合处理时的用药比例可…     

Leaf respiration at different canopy positions in sweetgum (Liquidambar styraciflua) grown in ambient and elevated concentrations of carbon dioxide in the field

Trees exposed to elevated CO2 partial pressure ([CO2]) generally show increased rates of photosynthesis and growth, but effects on leaf respiration are more variable. The causes of this variable response are unresolved. We grew 12-year-old sweetgum trees (Liquidambar styraciflua L.) in a Free-Air CO2 Enrichment (FACE) facility in ambient [CO2] (37/44 Pa daytime/nighttime) and elevated [CO2] (57/65 Pa daytime/nighttime) in native soil at Oak Ridge National Environmental Research Park. Nighttime respiration (R(N)) was measured on leaves in the upper and lower canopy in the second (1999) and third (2000) growing seasons of CO2 fumigation. Leaf respiration in the light (R(L)) was estimated by the technique of Brooks and Farquhar (1985) in the upper canopy during the third growing season. There were no significant short-term effects of elevated [CO2] on R(N) or long-term effects on R(N) or R(L), when expressed on an area, mass or nitrogen (N) basis. Upper-canopy leaves had 54% higher R(N) (area basis) than lower-canopy leaves, but this relationship was unaffected by CO2 growth treatment. In August 2000, R(L) was about 40% of R(N) in the upper canopy. Elevated [CO(2)] significantly increased the number of leaf mitochondria (62%), leaf mass per unit area (LMA; 9%), and leaf starch (31%) compared with leaves in ambient [CO(2)]. Upper-canopy leaves had a significantly higher number of mitochondria (73%), N (53%), LMA (38%), sugar (117%) and starch (23%) than lower-canopy leaves. Growth in elevated [CO2] did not affect the relationships (i.e., intercept and slope) between R(N) and the measured leaf characteristics. Although no factor explained more than 45% of the variation in R(N), leaf N and LMA were the best predictors for R(N). Therefore, the response of RN to CO2 treatment and canopy position was largely dependent on the magnitude of the effect of elevated [CO2] or canopy position on these characteristics. Because elevated [CO2] had little or no effect on N or LMA, there was no effect on R(N). Canopy position had large effects on these leaf characteristics, however, such that upper-canopy leaves exhibited higher R(N) than lower-canopy leaves. We conclude that elevated [CO2] does not directly impact leaf respiration in sweetgum and that barring changes in leaf nitrogen or leaf chemical composition, long-term effects of elevated [CO2] on respiration in this species will be minimal.     

Variations in dark respiration and mitochondrial numbers within needles of Pinus radiata grown in ambient or elevated CO2 partial pressure

Within-leaf variations in cell size, mitochondrial numbers and dark respiration rates were compared in the most recently expanded tip, the mid-section and base of needles of Pinus radiata D. Don trees grown for 4 years in open-top chambers at ambient (36 Pa) or elevated (65 Pa) carbon dioxide partial pressure (p(CO2)a). Mitochondrial numbers and respiratory activity varied along the length of the needle, with the highest number of mitochondria per unit cytoplasm and the highest rate of respiration per unit leaf area at the base of the needle. Regardless of the location of the cells (tip, middle or basal sections), needles collected from trees grown in elevated p(CO2)a had nearly twice the number of mitochondria per unit cytoplasm as those grown in ambient p(CO2)a. This stimulation of mitochondrial density by growth at elevated p(CO2)a was greater at the tip of the needle (2.7 times more mitochondria than in needles grown in ambient CO2) than at the base of the needle (1.7 times). The mean size of individual mitochondria was unaffected either by growth at elevated p(CO2)a or by position along the needle. Tree growth at elevated p(CO2)a had a variable effect on respiration per unit leaf area, significantly increasing respiration in the tip of the needles (+25%) and decreasing respiration at the mid-section and base of the needles (-14% and -25%, respectively). Although a simple relationship between respiration per unit leaf area and mitochondrial number per unit cytoplasm was found within each CO2 treatment, the variable effect of growth at elevated p(CO2)a on respiration along the length of the needles indicates that a more complex relationship must determine the association between structure and function in these needles.     

储藏对大豆营养品质的影响

用磷化铝片剂对混合的大豆进行熏蒸，再在室温下[28（±2）℃]对带壳的、脱壳的和大豆粉在密闭的塑料容器、村聚乙烯织物的聚丙烯袋和一般的聚丙烯袋里储藏12个月，以寻找较好的大豆储藏形式，保持营养品质。这项研究表明，干燥的带亮大豆储藏在密闭容器或储藏在村聚乙烯织物的聚丙烯袋内效果最好。去壳大豆和大豆粉不宜储藏在一般聚丙烯袋内或一般的麻袋内。储藏对大豆营养品质的影响@刘平来     

溴氰菊酯对绿豆象和四纹豆象杀虫活性的测定

在实验室条件下,溴氰菊酯在剂量0.25PPm时对绿豆象的有效作用达228天以上,在自然条件下,0.75PPm对四纹豆象的有效性达6个月以上。在自然条件下实验只延续了6个月。目前正在进行的另一研究表明活性将持续12个月以上。溴氰菊酯对第一代成虫和卵分别提供99.9和91％以上的防治作用,在第二代后,对隐蔽幼虫和若虫的防治效果只有92％。     

印度潮湿地区农村小麦储藏

印度70%的粮食由农民储藏,在印度东北部高湿度条件下(相对湿度75—85%),小麦种和小麦粮食的储藏是比较困难的。在透气的麻袋和不密闭的储器里储藏的小麦,由于它高度的吸湿性,吸收了空气中的水分。随着粮食水分的增加,害虫和螨的感染增加,霉菌发生,种子生活力降低。而在密闭条件下储藏,可使粮食免于虫霉感染,或者比在不密闭条件下粮食损失小。为了寻求最经济、最方便,而且造合农村储藏的设备和方法,印度 Assam 农业大学昆虫实验室对金属仓、水泥仓和竹篓等三种室内小麦储藏装具进行了评价。