肠炎沙门氏杆菌的出现已成为肉鸡生产的问题

鉴于肠炎沙门氏菌（Salmonella Enteritidis,SE）是通过垂直传播进行的这一事实,其预防方案必须围绕父母代种鸡。     

Using foresight to prepare animal health today for tomorrow's challenges

Foresight has been introduced in Canada in the area of animal health as a process to broaden thinking about the future and inform policy development. Its initial use and evolution through projects and studies over the past decade are described, demonstrating real action in animal health. Despite positive, continuing, and exciting results in animal health policy development, foresight's widespread acceptance and use thus far have been limited. Critical components for success, drawn from the Canadian experience, are described, and recommendations are offered for further action in animal health.     

Insect juvenile hormones: highly potent synthetic mimics

The substitution of a 7-alkoxy group for the 6,7-epoxy moiety in aryl terpenoid ethers having high juvenile hormone activity has produced several compounds exceptionally active against Tenebrio molitor. The most potent compound [7-ethoxy-1-(p-ethylphenoxy)-3,7-dimethyl-2-octene, called JH-25] is active at the level of 10 picograms per insect, or about 100 times more active than other promising juvenile hormone mimics so far reported. Compound JH-25 was also active against Tribolium confusum.     

Enhanced optical emission during Crab giant radio pulses

We detected a correlation between optical and giant radio pulse emission from the Crab pulsar. Optical pulses coincident with the giant radio pulses were on average 3% brighter than those coincident with normal radio pulses. Combined with the lack of any other pulse profile changes, this result indicates that both the giant radio pulses and the increased optical emission are linked to an increase in the electron-positron plasma density.     

Regulation of mitochondrial biogenesis in skeletal muscle by CaMK

Endurance exercise training promotes mitochondrial biogenesis in skeletal muscle and enhances muscle oxidative capacity, but the signaling mechanisms involved are poorly understood. To investigate this adaptive process, we generated transgenic mice that selectively express in skeletal muscle a constitutively active form of calcium/calmodulin-dependent protein kinase IV (CaMKIV*). Skeletal muscles from these mice showed augmented mitochondrial DNA replication and mitochondrial biogenesis, up-regulation of mitochondrial enzymes involved in fatty acid metabolism and electron transport, and reduced susceptibility to fatigue during repetitive contractions. CaMK induced expression of peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1), a master regulator of mitochondrial biogenesis in vivo, and activated the PGC-1 gene promoter in cultured myocytes. Thus, a calcium-regulated signaling pathway controls mitochondrial biogenesis in mammalian cells.     

Relationship between Grain Yield and Remotely-Sensed Data in Wheat Breeding Experiments

Data from aerial infrared photographs have recently been proposed as a complementary analytical tool for evaluating genotype performance in breeders' trials. Our objective was to establish the relationships between spring wheat grain yield and remotely-sensed data in a variety experiment. Large genotype differences (P ≤ 0.05) in grain yield, red, and near infrared reflectance values occurred. Significant (P ≤ 0.05) regressions between grain yield and remoteley-sensed data were observed for two dates of flight, but these functions varied between dates of flight. A normalized difference vegetative index, as an estimate of crop productivity, indicated that spring wheats with the highest grain yields may show correspondingly high dry matter production. However, low r² values for the remotely-sensed values suggest that much of the variability is not explained by these models. Future research must develop more accurate methods of remotely-sensed analysis, including standardizing the images, identifying the correct time with respect to stage of crop development for infrared photographs, incorporating crop harvest index data into the models, and adjusting for identified spatial variation.     

Chemical cues promote settlement in larvae of the green-lipped mussel, Perna canaliculus

The large (70,000 tonnes) mussel aquaculture industry for the endemic New Zealand green-lipped mussel, Perna canaliculus Gmelin, currently relies almost entirely (80%) on wild caught seed that is often harvested attached to great quantities of floating algae. Natural vagaries in catches of wild mussel seed frequently result in shortages of mussel seed that, at times, have severely affected commercial aquaculture production. Both field and laboratory experiments were used to establish that chemical cues derived from algae significantly increase settlement of mussel larvae on artificial substrates. This is the first time an algal chemical cue has been implicated in the settlement behavior of P. canaliculus larvae. These results have potential commercial implications for improving mussel seed supply through inducing higher or more reliable levels of mussel settlement for aquaculture seed collection.     

大肠杆菌感染可造成严重损失

大肠杆菌感染对世界养禽业造成了重大损失。大肠杆菌是商品家禽肠道中的正常栖居菌 ,并且还是环境中无处不在的 ,但其产毒菌株会引起局部或全身感染 ,结果造成鸡群死亡率增高 ,使商品产蛋鸡和种鸡的产蛋率下降 ;还可使肉鸡的生长率下降 ,胴体质量下降以及加工时废弃率增高     

Seasonal patterns of carbohydrate reserves in red spruce seedlings

We studied seasonal dynamics of carbohydrate storage in red spruce (Picea rubens Sarg.) seedlings by measuring starch and sugar concentrations of old needles (>/= one year old), new needles (< one year old), stems, and roots in two stands in the Green Mountains of Vermont. Although the two stands differed in many site characteristics including percent slope, aspect, soil type, drainage, and 564 m in elevation, concentrations and seasonal patterns of carbohydrates were similar for the two stands. For all tissues, starch concentrations peaked in late spring, declined through summer, and reached a minimum in winter. Sugar concentrations were greater than starch concentrations in all months except May and June. Sugar concentrations peaked in winter, and old needles showed a significant increase in sugar concentration between February and March. This increase in sugar concentration occurred without any reduction in localized starch concentrations or reductions in sugar or starch concentrations in new needles, stems or roots. Because March measurements were made toward the end of a prolonged thaw, a time when increases in photosynthesis have been documented for red spruce, it is likely that the March increase in sugar concentrations resulted from photosynthesis during the thaw. Compared with stems and roots, needles generally contained the highest concentration of carbohydrates and exhibited the greatest seasonal change in carbohydrate concentration. Needles were also the largest reservoir of carbohydrates throughout the year, especially during winter. Because of the critical roles of needles in photosynthesis and storage of carbohydrates, we conclude that any factors that disrupt the accumulation or availability of carbohydrates in red spruce needles will greatly alter plant carbon relations.