水泡性口炎病毒核蛋白基因在大肠杆菌中的表达和鉴定

根据已经发表的IN型水泡性口炎病毒(VSV)核蛋白(N)基因的序列设计1对特异引物,应用RT-PCR技术扩增编码IN VSV的N基因,将PCR产物按相应的阅读框架克隆到表达载体pET-32a。并将重组质粒转化入大肠杆菌 BL21株,以1．0 mmol·L-1 IPTG在37℃的条件下诱导,N基因得到了高效表达。经过聚丙烯酰胺凝胶电泳以及用 VSV阳性血清进行Western blotting试验,结果表明所表达的融合蛋白产物分子质量与预期的65．3 ku相符。     

中国施用生物炭对番茄产量和品质效应的Meta分析

为定量分析生物炭施用对番茄产量和品质的时空效应和影响机制,同时为番茄生产中生物炭合理施用量的确定提供依据。该研究通过检索文献整合已发表的相关田间试验数据,采用Meta-analysis法分析了生物炭施用条件下,生物炭特性、土壤条件、田间管理措施与时空特性对番茄产量和品质的综合效应,并对各影响因素进行通径分析。结果表明：施用生物炭显著增加了番茄产量、果实Vc、可溶性糖和可溶性固形物含量（P<0.05）,增长率分别为 30.7%（95%置信区间（confidence interval,CI） 为27.6%～33.9%）、13.8%（95% CI为10.8%～16.9%）、6.7%（95% CI为3.3%～10.2%）和10.7%（95% CI为5.8%～15.8%）,而番茄果实硝酸盐含量降低了3.1%（95% CI为-6.7%～0.8%）,对番茄果实糖酸比含量增加效应不显著（95% CI为-3.0%～7.9%）;番茄产量效应的亚组分析表明,生物炭施用在不同时间和区域特征下对番茄增产效应影响显著（P＜0.01）,随着时间的推移,生物炭施用对番茄增产效应呈波动式增长趋势,华北、东北农田区的番茄增产效应不显著;土壤有机质含量与番茄增产率呈正相关关系,土壤pH值与番茄增产率呈负相关关系,番茄增产率随土壤全氮及硝酸钾含量的增加呈先增后减趋势;田间管理措施对番茄产量效应分析结果表明,生物炭施加量>40～80 t/hm²时,增产率可达37.8%（95% CI为33.5%～42.1%）,生物炭热解温度在400～600 ℃内,生物炭pH值控制在>8～9为最优;生物炭施用量、生物炭pH值和产量年份是影响生物炭增产效果的3个主要因素。研究结果可为番茄生产中科学、合理生物炭施用量的确定提供理论支撑。     

Comparison of the pharmacokinetics and thermal antinociceptive pharmacodynamics of 20 µg kg−1 buprenorphine administered sublingually or intravenously in cats

Little is known about the analgesic action of buprenorphine (BUP) in cats. Relative to man, the cat has a more alkaline oral pH, which may make this an effective route for administering BUP in this species. This study aimed to assess and compare the pharmacokinetics and pharmacodynamics of sublingual (S‐L) and IV administration of BUP. Thermal threshold (TT) was measured and blood samples were collected following IV or S‐L administration (20 µg kg^?1) of the injectable formulation. Six cats (five spayed females, one castrated male, 4.1–6.6 kg) were used. Each cat received both treatments in a randomized cross‐over study design with 1 month between experiments. Twenty‐four hours prior to each study, the lateral thorax of each of the cats was shaved, cephalic and jugular catheters placed, and oral pH measured. On the day of the study, TT was measured using a ‘thorax‐mounted’ thermal threshold‐testing device specifically developed for cats. The cats were free to move around. Skin temperature was recorded before each test, then the heater activated. When the cat responded by flinching, turning, or jumping, the stimulus was terminated and the threshold temperature was recorded. The thermal threshold cut‐off point was 55.5 °C. Three baseline thresholds were recorded before treatment with S‐L or IV (via cephalic catheter) BUP (20 µg kg^?1). Blood was withdrawn (jugular) at 1, 2, 4, 6, 10, 15, 30, 45, 60 minutes and at 2, 4, 6, 8, 12, and 24 hours post‐administration. TT was measured every 30 minutes?6 hours, 1–12 hours, and at 24 hours post‐administration. Plasma was immediately separated, stored at ?20.5 °C, and assayed within 4 months using a commercially available ¹²⁵I radioimmunoassay. Threshold data were analyzed using anova with a repeat factor of time. No adverse effects were noted. Pupils were dilated for up to 9 hours post‐BUP. Behavioral changes were calm euphoria. Measured oral pH was 9 in each cat. Pre‐treatment mean threshold (±SD) was 41.2 ± 0.9 °C in the S‐L group and 40.8 ± 0.85 °C in the IV group. There were no significant differences between the groups with respect to thresholds over time (p = 0.72). Thresholds were significantly increased from 30 to 360 minutes in both the groups (>44.615 °C). Peak plasma BUP (C_max) was lower (11 ± 6.7 ng mL^?1vs. 92.9 ± 107.9 ng mL^?1) and occurred later (T_max) (30 minutes vs. 1 minute) after S‐L compared to IV administration, respectively. BUP (20 µg kg^?1)‐administered S‐L or IV provided antinociception between 30 and 360 minutes after administration. Plasma levels did not correspond to TT.     

Managing anthelmintic resistance: Is it feasible in New Zealand to delay the emergence of resistance to a new anthelmintic class?

The recent registration in New Zealand of the first new class of broad-spectrum anthelmintic, for use against nematode parasites of ruminants, in nearly three decades has raised the possibility that parasite management practices could be improved to minimise the emergence of resistance to the new drug. A review of knowledge pertaining to the selection of anthelmintic resistance in nematode parasites of sheep highlights a number of management practices which could be altered to achieve this.

A number of previously common practices such as whole-flock treatment of adult ewes around lambing, and treatment of lambs as they are moved onto pastures with low parasite contamination have been clearly identified as high risk for selecting resistant parasites. Once high-risk practices have been identified steps can be taken to either eliminate their use or mitigate the associated risk. Much of the focus on the management of resistance around the world is on the retention of susceptible genotypes in refugia. While approaches to retaining unselected parasites are likely to vary around the world, empirical studies indicate that the practice is likely to be effective at slowing the development of resistance. The challenge for farmers and advisors will be to strike a balance between retaining sufficient susceptible para-sites to usefully delay the development of resistance while not unduly compromising animal performance and farm profitability. The merits of combining different classes of anthelmintic in order to slow the development of resistance remains somewhat contentious in some countries. However, the attributes of oral anthelmintics are such that they seem likely to meet most, if not all, of the criteria for combinations to be highly effective at slowing the build-up of resistance in nematode parasites.

It is evident that considerable progress has been made in understanding the factors involved in selecting anthelmintic-resistant nematodes since the last broad-spectrum anthelmintic class was released in the early 1980s. Therefore, it should be possible to manage a new class of anthelmintic in such a way as to significantly extend its effective life. The challenge is likely to be in convincing farmers of the merits of adopting such pro-active strategies.     

沙芥愈伤组织培养的初步研究

采用沙芥种子作为无菌外植体来源时,以0.1升汞消毒10～12min的效果较好.下胚轴和子叶均在MS+2,4-D 0.01 mg·L-1+NAA 2 mg·L-1+6-BA 0.5 mg·L-1+3.0蔗糖+0.5琼脂(pH5.8)中可诱导出愈伤组织.愈伤组织的最佳继代培养基为MS+NAA 2mg·L-1+KT0.5 mg·L-1+3.0蔗糖+0.5琼脂(pH5.8).     

甘露寡糖对断奶仔猪肠道菌群的影响

选取28日龄断奶的三元[杜×(大×长)]杂交仔猪96头,平均体重为(7．46±0．38)kg,按体重和 性别随机分为4个处理组,每个处理组3个重复,每个重复8头仔猪,公母各半。第1个处理组为空白 组,第2、3、4个处理组在相同的基础日粮中分别添加0．1％、0．2％和0．4％的甘露寡糖,研究甘露寡糖对断 奶仔猪肠道菌群的影响。结果表明:1、各实验组肠道大肠杆菌的浓度极显著低于对照组。2、第3组和 第4组其结肠、盲肠和直肠中双歧杆菌增殖显著。第2组中只有结肠中双歧杆菌显著高于对照组,但盲 肠和直肠中双歧杆菌增殖不明显。3、各个处理组肠道中乳酸杆菌的浓度与对照组相比差异不显著。     

Pharmacokinetics of carprofen and firocoxib for medication control in racing greyhounds

Animals used in sport should be treated as required to ensure animal welfare but any such use of medication should also be controlled to ensure integrity. Pharmacokinetic studies on groups of six greyhounds were performed to measure plasma and urine levels of carprofen and firocoxib to inform medication control advice. Using the standard methodology for medication control the Irrelevant Plasma Concentration was determined as 20 and 2 ng/mL for carprofen and firocoxib, respectively. The Irrelevant Urine Concentration was also determined as 0.3 and 2 ng/mL for carprofen and firocoxib, respectively. These Irrelevant Plasma and Urine Concentrations will allow laboratory Screening Limits, Detection Times and Withdrawal Time advice to be determined and publicised by regulators of greyhound racing. The Screening Limits will also inform Recommended Limits of Detection if meat-containing residues of these medications are fed to greyhounds.     

大果沙棘全光照喷雾嫩枝扦插育苗试验

在全光照自动喷雾条件下,对大果沙棘嫩枝插条采用IBA、NAA、ABT-l号、ABT-2号4种植物生长调节剂,各3种浓度梯度的浸泡处理2 h,可明显促进插条生根。在供试的13种处理中,IBA 100 m g.L-1处理效果最好,生根率可达到98.8%。