口蹄疫病毒VP1基因的原核可溶性表达

针对重组原核表达载体表达目的蛋白以包涵体形式存在的问题,作者对影响外源蛋白表达的IPTG的浓度、温度、时间等因素均进行了探索,以观察VP1蛋白的可溶性情况。通过PCR技术将VP1基因克隆至pGEM-T载体中,然后将pET-28a(+)和pGEM-T载体分别进行双酶切,构建重组的pET-28a-VP1载体,将重组载体转化至BL21中,诱导后经SDS-PAGE检测可见约29 ku的目的蛋白条带。插入的外源目的蛋白主要以包涵体的形式存在,上清中的可溶性蛋白甚微。试验结果表明,这可能与蛋白本身的氨基酸组成有重要关联。     

维生素C对蛋鸡部分免疫器官指数及新城疫抗体效价的影响

为了探讨不同剂量维生素C（vitamin C,VC）对蛋鸡免疫机能的影响,将240只体重相近的45日龄罗曼褐壳蛋鸡随机分为A、B、C、D、E 5组,每组4个重复,每个重复12只。A组不进行免疫,日粮中也不添加VC,为对照组,B、C、D、E 4组颈部皮下注射新城疫Ι系疫苗进行免疫,并在该4组日粮中分别添加0、250、500、750 mg/kg的VC,分4周测脾脏、胸腺、法氏囊等免疫器官指数及血清中新城疫HI抗体效价。结果显示,添加VC的C、D、E组,蛋鸡脾脏、胸腺等免疫器官指数均显著（P＜0.05）或极显著（P＜0.01）高于B组,法氏囊指数在第21、28天显著高于B组（P＜0.05）,新城疫HI抗体效价极显著高于B组（P＜0.01）,且以日粮中500 mg/kg的VC添加量效果最好。由此可见,在鸡的日粮中适当添加VC能促进脾脏、胸腺等免疫器官的生长发育,显著增强免疫系统合成分泌抗体的能力,从而提高鸡体的免疫机能。     

Protein kinase C isoforms in the porcine corpus luteum: Temporal and spatial expression patterns

Porcine corpora lutea (CL) fail to show a luteolytic response to prostaglandin-F-2α (PGF-2α) (ie, luteolytic sensitivity, or LS) until ∼day 13 of the estrous cycle. In view of the importance of protein kinase C (PRKC) in PGF-2α signal transduction, it was hypothesized that limiting levels of 1 or more PRKC isoforms may explain the lack of LS before day 13. This hypothesis was tested by examining expression of mRNA and protein, and the cellular localization patterns of the 11 PRKC isoforms throughout the porcine estrous cycle, to determine whether PRKC expression correlates with and thus may be associated with the control of the acquisition of LS in the pig. The expression patterns show that for most PRKC isoforms (ie, PRKC alpha, beta 1, beta 2, delta, epsilon, theta, iota, and zeta), mRNA was maximally expressed on day 7 or day 10 (protein kinase D1 only) of the cycle, whereas PRKCs gamma, eta, and lambda were unchanged. At the protein level, only PRKC epsilon (PRKCE) significantly changed during the estrous cycle and was elevated on day 13 (versus days 4, 7, and 15; P < 0.05). By immunofluoresence, most PRKC isoforms, including PRKCE, were localized to steroidogenic large luteal cells (LLC) and small (nonendothelial cell) luteal cell subtypes (SLC). In conclusion, since the increase in PRKCE protein expression (day 13) occurred coincidentally with the onset of LS (≥day 12), these results support a potential role for PRKCE in control of the acquisition of LS in the pig.     

晚秋温度对苜蓿地上部游离脯氨酸、可溶性糖和POD活性的影响

通过对9个不同苜蓿Medicago sativa品种地上部游离脯氨酸、可溶性糖和POD活性的研究,揭示晚秋温度变化对上述指标变化的影响,结果表明：9月10日-10月10日,随着温度的降低,3种不同秋眠类型的苜蓿地上部游离脯氨酸含量都呈上升趋势,其中高度秋眠类型苜蓿的变化幅度最大;不同秋眠类型苜蓿地上部可溶性糖变化趋势有所不同,低度和高度秋眠类型苜蓿变化幅度比较剧烈,说明在贮藏类营养物质方面,低度和高度秋眠类型苜蓿更为敏感,二者变化趋势恰好相反,中度秋眠类型苜蓿介于二者之间;不同秋眠类型苜蓿地上部过氧化物酶（POD）活性都经历逐步上升的趋势,中度和高度秋眠类型苜蓿POD活性变幅相对于低度秋眠类型大,说明中度和高度秋眠类型苜蓿地上部对于气温的变化更敏感。     

复方恩诺沙星可溶性粉对畜禽主要致病菌的体外抑菌效果

采用纸片扩散法(K-B法)测定复方恩诺沙星可溶性粉对畜禽主要致病菌的敏感性,采用试管倍比稀释法测定复方恩诺沙星可溶性粉对畜禽主要致病菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC)。结果表明,病原性大肠埃希菌、绿脓杆菌、金黄色葡萄球菌、鸡巴氏杆菌、猪巴氏杆菌和链球菌对复方恩诺沙星可溶性粉敏感,复方恩诺沙星可溶性粉对畜禽主要致病菌的MIC为0.0279μg/mL~3.575μg/mL,MBC为0.055μg/mL~7.11μg/mL。     

Anti-obesity activity of diglyceride containing conjugated linoleic acid in C57BL/6J ob/ob mice

This study was to investigate the anti-obesity effects of diglyceride (DG)-conjugated linoleic acid (CLA) containing 22% CLA as fatty acids in C57BL/6J ob/ob male mice. There were four experimental groups including vehicle control, DG, CLA, and DG-CLA. The test solutions of 750 mg/kg dose were orally administered to the mice everyday for 5 weeks. CLA treatments significantly decreased mean body weight in the obese mice throughout the experimental period compared to the control (p < 0.01). All test solutions significantly decreased the levels of triglyceride, glucose and free fatty acids in the serum compared with control (p < 0.05). The levels of total cholesterol were also significantly reduced in DG and DG-CLA groups compared with the control group (p < 0.05). CLA significantly decreased weights of renal and epididymal fats compared with the control (p < 0.05). DG and DG-CLA also significantly decreased the epididymal fat weights compared with the control (p < 0.05). A remarkable decrease in the number of lipid droplets and fat globules was observed in the livers of mice treated with DG, CLA, and DG-CLA compared to control. Treatments of DG and CLA actually increased the expression of peroxisome proliferator-activated receptor gamma. These results suggest that DG-CLA containing 22% CLA have a respectable anti-obesity effect by controlling serum lipids and fat metabolism.     

Stable carbon isotopes accurately predict diet selection by sheep fed mixtures of C3 annual pastures and saltbush or C4 perennial grasses

The stable carbon isotope technique has been widely used to infer the dietary ecology of a range of animal species; however calibration of the technique with animals fed known diets is essential for accurate back-calculation of dietary preferences. The aim of this study was to identify suitable samples and back-calculation methods to predict short-term (2 to 3 week) dietary selection by sheep among plants with C₃ and C₄ photosynthetic pathways. Variation in integration time of dietary carbon into plasma and faeces; diet-tissue discrimination of carbon isotopes (fractionation) and the importance of accounting for the digestible or indigestible components of the diet was investigated. The results indicate that faecal and rumen samples provided the most accurate prediction of short term dietary changes in sheep selecting between C₃ and C₄ plants. The most accurate back-calculation method for these samples used δ¹³C of the C₃ and C₄ plants and accounted for both diet-tissue discrimination and differences in the indigestibility between the C₃ and C₄ forage. For faecal samples, the organic matter content of the diet originating from C₄ plants could be predicted with a mean error as low as 2.7%. Wool and plasma samples were not conducive to predicting proportion of C4 forage in the diet within 18 days after a change in diet; however plasma could be used to discriminate between animals fed 100% C₃ and C₄ diets after 3 days. The δ¹³C technique provides a valuable tool for researchers when designing pastures for dual environmental and production purposes. An understanding of what sheep select allows for development of appropriate grazing management strategies to optimise productivity and/or persistence of target species.     

Prediction of model pools for a long‐term experiment using near‐infrared spectroscopy

Fourty‐one soil samples from the “Eternal Rye” long‐term experiment in Halle, Germany, were used to test the usefulness of near‐infrared spectroscopy (NIRS) to differentiate between C derived from C₃ and C₄ plants by using the isotopic signature (δ¹³C) and to predict the pools considered in the Rothamsted Carbon (RothC) model, i.e., decomposable plant material, resistant plant material, microbial biomass, humified organic matter, and inert organic matter. All samples were scanned in the visible‐light and near‐infrared region (400–2500 nm). Cross‐validation equations were developed using the whole spectrum (first to third derivative) and a modified partial least‐square regression method. δ¹³C values and all pools of the RothC model were successfully predicted by NIRS as reflected by RSC values (ratio between standard deviation of the laboratory results and standard error of cross‐validation) ranging from 3.2 to 3.4. Correlations analysis indicated that organic C can be excluded as basis for the successful predictions by NIRS in most cases, i.e., 11 out of 16.     

Soil‐carbon turnover under different crop management: Evaluation of RothC‐model predictions under Pannonian climate conditions

Despite the importance of soil organic matter (SOM), very few long‐term data concerning soil organic‐C dynamics are available for calibrating and evaluating C models. The long‐term ¹⁴C‐turnover field experiment, established in 1967 in Fuchsenbigl, Lower Austria, offers the unique opportunity to follow the fate of labeled C under different crop‐management systems (bare fallow, spring wheat, crop rotation) over a period of more than 35 y. Compared with the crop‐rotation and spring‐wheat treatments, the decline of total organic C was largest in the bare‐fallow treatments, because no significant C input has occurred since 1967. Nonetheless, the decline was not as fast as predicted with the original RothC‐26.3‐model decomposition rate constants. In this work, we therefore calibrated the Roth‐C‐26.3 model for the Pannonian climatic region based on the field‐experiment results. The main adjustment was in the decomposition rate constant for the humified soil C pool (HUM), which was set to 0.009 instead of 0.02 y^–1 as determined in the original Rothamsted field trial. This resulted in a higher HUM pool in the calibrated model because of a longer turnover period (111 vs. 50 y). The modeled output based on the calibrated model fitted better to measured values than output obtained with the original Roth‐C‐26.3‐model parameters. Additionally, the original decomposition rate constant for resistant plant material (RPM) was changed from 0.3 to 0.6 y^–1 to describe the decomposition of ¹⁴C‐labeled straw more accurately. Application of the calibrated model (modified HUM decomposition rate) to simulate removal of crop residues showed that this can entail a long‐term decline of SOM. However, these impacts are strongly dependent on the crop types and on environmental conditions at a given location.