猪繁殖和呼吸综合征的研究进展

从近二年来已经发表或即将发表的文献来看,猪繁殖和呼吸综合征的研究已经取得了一些极为显著的进展。     

Endometrial nitric oxide synthase activity in mares susceptible or resistant to persistent breeding‐induced endometritis and the effect of a specific iNOS inhibitor in vitro

Emerging research suggests that the nitric oxide system may play a role in persistent breeding‐induced endometritis (PBIE) in the mare. Differences in uterine nitric oxide (NO) levels between mares susceptible or resistant to PBIE and a dose‐dependent inhibitory effect of NO on uterine contractility have been demonstrated. The objectives of this study were to investigate the difference in total nitric oxide synthase (NOS) activity of the endometrium between susceptible and resistant mares and the effect of a specific inducible nitric oxide synthase (iNOS) inhibitor on the endometrial NOS activity in vitro. Six susceptible and six resistant mares were selected based on preset criteria and the results of an intrauterine challenge with killed spermatozoa during oestrus. Endometrial biopsy samples were collected 24 hr post‐challenge and cultured at 37°C for 24 hr in L‐arginine supplemented minimum essential medium with or without a specific iNOS inhibitor (1,400 W dihydrochloride, 1 mM). The medium and the cultured endometrial tissue were collected after 24 hr of culture and assayed for NO and total protein, respectively. Total NO content of the medium, normalized to endometrial tissue wet weight or total protein, was used as a measure of endometrial NOS activity. Non‐parametric tests were applied for statistical analysis. Susceptible mares had significantly greater endometrial NOS activity than resistant mares. The iNOS inhibitor treatment significantly reduced NOS activity in endometrial samples derived from susceptible and resistant mares. These findings provide a basis for in vivo testing of specific iNOS inhibitors as preventative or therapeutic options for PBIE in mares.     

黄土藻类回接之生境条件研究

通过液体藻种固相接种培养试验,对人工培养藻类结皮的生态环境条件进行了研究,探讨了温度、光照、水分对藻类生长繁殖的影响规律。结果表明:温度条件对藻类的生长有影响,20℃和室温条件下藻类生物量平均增长率较小,说明其生长比35℃条件下稳定;从光照条件来看,全光和暗光条件下藻类生物量逐渐减少,而弱光条件下生物量持续增加,说明弱光条件下藻类生长最旺盛;水分是影响藻类生长的重要条件,土壤含水量达到30%～35%时藻类生长良好,说明足够的水分供给能够增强液体藻种对环境的适应性,因此,在藻类接种的初期,加强水分的供应能够保证人工培养藻类结皮的成活率。     

黄土高原丘陵沟壑区放牧林草地土壤团聚体性质研究

通过放牧试验的方法,研究土壤团聚体含量和破坏率,以探讨不同放牧强度、不同放牧畜种、不同放牧植被类型条件下表土的团聚体(＞ 0.25 mm)含量和破坏率.结果表明:放牧强度对土壤性质有影响,重度放牧下土壤团聚体含量最小;从畜牧羊种选择来看,绵羊相对于山羊来说对土壤结构破坏较小,土壤中团聚体含量较高;对于不同植被类型,放牧...     

沿海防护林主要病虫害发生原因及防治对策

本文对日照沿海防护林17种主要病虫害发生原因进行了全面分析，提出了相应的防治对策。     

Recent advances in computational fluid dynamics relevant to the modelling of pesticide flow on leaf surfaces

Increasing societal and governmental concern about the worldwide use of chemical pesticides is now providing strong drivers towards maximising the efficiency of pesticide utilisation and the development of alternative control techniques. There is growing recognition that the ultimate goal of achieving efficient and sustainable pesticide usage will require greater understanding of the fluid mechanical mechanisms governing the delivery to, and spreading of, pesticide droplets on target surfaces such as leaves. This has led to increasing use of computational fluid dynamics (CFD) as an important component of efficient process design with regard to pesticide delivery to the leaf surface. This perspective highlights recent advances in CFD methods for droplet spreading and film flows, which have the potential to provide accurate, predictive models for pesticide flow on leaf surfaces, and which can take account of each of the key influences of surface topography and chemistry, initial spray deposition conditions, evaporation and multiple droplet spreading interactions. The mathematical framework of these CFD methods is described briefly, and a series of new flow simulation results relevant to pesticide flows over foliage is provided. The potential benefits of employing CFD for practical process design are also discussed briefly. © Crown copyright 2009. Reproduced with permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

Aspergillosis in camels affected with a specific respiratory and enteric syndrome

During the summer of 1990 deaths, occurred in racing camels (Camelus dromedarius) associated with a specific disease syndrome. Clinical signs included pyrexia, coughing, lachrymation, oedema of the throat and submandibular region and enlargement of submandibular lymph nodes. In terminal cases nervous signs were present and sometimes there was bloody diarrhoea and vomiting. Of 480 camels at least 70 animals were affected with the disease and about 40 died. Morbidity and mortality was greater in camels recently imported. Consistent necropsy findings were extensive petechial and ecchymotic haemorrhage beneath the epicardium, endocardium and visceral pleura and in the mediastinal lymph nodes, and haemorrhagic oedema of the pharyngeal and laryngeal areas. Haemorrhages occurred more variably in abdominal organs and on the omasal and abomasal mucosa. Bronchopneumonia, omasitis and abomasitis were observed on microscopic examination, together with liver and kidney lesions of presumed toxic origin. Fungal hyphae and, occasionally, the characteristic conidial morphology of Aspergillus fumigatus were seen in sections and direct smears from lesions in the respiratory and alimentary tracts. A fumigatus was cultured from trachea, bronchi, bronchioles, lung tissue, heart blood, omasum, abomasum, ileum and submandibular lymph nodes. Whether the role of Aspergillus in the overall syndrome is primary or secondary has not been established; no other potential aetiological agent has been identified.     

荷叶总生物碱降脂减肥作用的体内外试验

通过体内、体外试验探究荷叶总生物碱的降脂减肥作用.给予高脂血症大鼠模型组不同剂量荷叶总生物碱和降脂药物辛伐他汀(阳性药物对照组),观察荷叶总生物碱对高脂血症大鼠体质量、体脂以及血清脂质相关指标的影响;用对硝基苯酚法检测不同质量浓度荷叶总生物碱处理对大鼠胰脂肪酶活性的影响.结果显示:荷叶总生物碱能显著降低高脂血症大鼠的体质量,显著降低血清总胆固醇、血清甘油三酯、低密度脂蛋白胆固醇含量,显著降低谷草转氨酶、谷丙转氨酶活性以及动脉粥样系数,升高高密度脂蛋白胆固醇/血清总胆固醇比值;荷叶总生物碱能抑制脂肪酶活性,抑制类型为非竞争性抑制;在荷叶总生物碱质量浓度为12.5～600μg/mL范围内,对脂肪酶的抑制效果随其质量浓度的增加而增强,在600μg/mL时达到最大抑制率,为25.6%,当荷叶总生物碱质量浓度继续增加时,抑制率趋于平缓,保持在最大值附近.体内、体外试验结果均表明,荷叶总生物碱类物质具有降脂减肥作用,提示其可能具有预防肥胖、调节脂代谢紊乱的功效.