Evaluation of 12-month interval methods for estimating animal-times at risk in a traditional African livestock farming system

Demographic parameters are useful for assessing productivity and dynamics of tropical livestock populations. Common parameters are the annual instantaneous hazard rates, which can be estimated by m/T (where m represents the number of the considered demographic events occurred during the year and T the cumulated animal-time at risk). Different approaches are encountered in the literature for computing T from on-farm survey data. One crude approach (“the 12-month interval approach”) only uses estimations of herds’ sizes at beginning and end of the year and aggregated counts of demographic events over the year. I evaluated the potential biases in using four 12-month interval methods (M1–M4) to estimate T. Biases were evaluated by comparing the 12-month estimates to gold-standard values of T. Data came from long-term herd monitoring on cattle and small ruminants in extensive agro-pastoral systems. Animal-times at risks were correctly estimated in average by methods M1, M2 and M4 (average relative biases <=6% in absolute values), except for adult-male small ruminants. For young animals, M2 and M4 showed equivalent biases. M2 is simple to implement and has the advantage of being applicable for any age-group, although M4 is only applicable for young animals. M3 was highly biased and I do not recommend it. Although accurate in average, 12-month interval methods showed highly variable biases. This variability results from interactions between the dates delimiting the 12-month interval and the distributions of the demographic events over time. This phenomenon is particularly important for the adult-male small ruminants. Based on the bias variability observed in the study, the user of 12-month interval methods has to remember that they only provide approximate results and that they cannot completely replace the gold-standard approaches.     

中、意蜂Atg12基因克隆表达及生物信息学分析

试验旨在探究自噬相关基因Atg12(autophagy-related 12 gene)在中华蜜蜂(中蜂)、意大利蜜蜂(意蜂)中的表达差异,为探讨中蜂抗螨分子机理提供参考。参照GenBank中东方蜜蜂Atg12基因序列(登录号:XM_017048509.1)设计引物,扩增中、意蜂头部组织Atg12基因,并对其进行克隆、测序、原核表达及其氨基酸序列和蛋白结构分析,同时采用实时荧光定量PCR技术分析该基因在中、意蜂头部组织中的表达差异。结果显示,本试验成功扩增出大小为450 bp的目的片段,并表达出大小约42 ku重组蛋白;遗传进化树分析表明,在Atg12基因进化过程中,中蜂(Apis cerana cerana)、意蜂(Apis mellifera)、大蜜蜂(Apis dorsata)和小蜜蜂(Apis florea)亲缘关系较近;重组蛋白生物信息学分析显示,该蛋白的二级结构中共含有6个多肽结合位点、6个β-折叠和4个α-螺旋,分子质量约为16.13 ku,等电点为6.73;实时荧光定量PCR结果显示,Atg12基因在中蜂头部组织中表达极显著高于意蜂(P<0.01)。本试验结果为后续深入研究Atg12基因在中蜂抗螨上的作用机制提供了参考。     

Cytokine response in Balb/c mice infected with Francisella tularensis LVS and the Pohang isolate

We investigated the immune response induced by the Francisella (F.) tularensis live vaccine strain (LVS) and the Pohang isolate. After the Balb/c mice were infected intradermally (i.d) with 2 × 10⁴ cfu of F. tularensis LVS and Pohang, respectively, their blood and organs were collected at different times; 0, 3, 6, 24, 72, 96, 120 and 168 h after infection. Using these samples, RT-PCR and ELISA analysis were carried out for the comparative study of the cytokines, including TNF-α, INF-γ, IL-2, IL-4, IL-10 and IL-12. In the Pohang-infected mice at 120 h, the liver showed a 53 times higher level of TNF-α and a 42 times higher level of IFN-γ than the respective levels at the early time points after infection. The levels of TNF-α and IFN-γ induced by LVS were 5 times lower than those induced by the Pohang isolate. Also, the organs from the Pohang-infected mice showed higher levels of TNF-α, IFN-γ, IL-10 and IL-12 than the levels in the LVS-infected mice. The blood from the Pohang-infected mice at 120 h revealed about a 40 times increased level of IFN-γ, and IL-10 was also increased by 4 times at 96 h compared to an early infection time point, while IL-4 was not induced during the whole infection period. These results suggest that F. tularensis may induce a Th1-mediated immune response to in vivo infection and the Pohang isolate has a higher capacity than the LVS to induce an acute immune response in Blab/c mice.     

E12 technique: Conventional epoxy resin sheet plastination

Epoxy plastination techniques were developed to obtain thin transparent body slices with high anatomical detail. This is facilitated because the plastinated tissue is transparent and the topography of the anatomical structures well preserved. For this reason, thin epoxy slices are currently used for research purposes in both macroscopic and microscopic studies. The protocol for the conventional epoxy technique (E12) follows the main steps of plastination—specimen preparation, dehydration, impregnation and curing/casting. Preparation begins with selection of the specimen, followed by freezing and slicing. Either fresh or fixed (embalmed) tissue is suitable for epoxy plastination, while slice thickness is kept between 1.5 and 3 mm. Impregnation mixture is made of epoxy E12 resin plus E1 hardener (100 ppw; 28 ppw). This mixture is reactive and temperature sensitive, and for this reason, total impregnation time under vacuum at room laboratory temperature should not last for more than 20–24 hr. Casting of impregnated slices is done in either flat chambers or by the so‐called sandwich method in either fresh mixture or the one used for impregnation. Curing is completed at 40°C to allow a complete polymerization of the epoxy‐mixture. After curing, slices can be photographed, scanned or used for anatomical study under screen negatoscope, magnification glass or fluorescent microscope. Based on epoxy sheet plastination, many anatomical papers have recent observations of and/or clarification of anatomical concepts in different areas of medical expertice.     

绿色木霉菌T12对茄子幼苗根系防御反应酶系的影响

试验研究了绿色木霉菌T12的分生孢子和厚垣孢子对不同抗、感黄萎病茄子品种幼苗植株防御酶系的影响.结果表明:经木霉菌T12处理的不同抗、感茄子品种幼苗根系与抗性物质合成相关的PAL、POD、CAT和SOD存在明显变化,证明茄子根系经诱导后可产生植保素等相关物质参与抵抗黄萎病,其中抗病品种比感病品种作用明显,厚垣孢子的诱抗作用比分生孢子显著.     

共轭亚油酸对C2C12肌细胞生脂和生肌分化的影响

本研究分析了共轭亚油酸(CLA)对C2C12肌细胞生脂转分化和生肌分化的影响。分别培养并诱导C2C12鼠源肌细胞生脂转分化和正常的生肌分化,同时分别使用终浓度为50μmol/L的c9,t11-CLA和t10,c12-CLA处理细胞,并设对照组,取生脂转分化第10天和生肌分化第8天的细胞用于实时定量PCR检测,观察c9,t11-CLA和t10,c12-CLA对C2C12肌细胞不同分化的影响。结果表明:1)与对照组相比,c9,t11-CLA促进了C2C12肌细胞的生脂转分化,显著增加了细胞内甘油三酯(TG)含量(P0.05),显著上调了细胞内脂肪酸合成酶(FAS)、CCAAT增强子结合蛋白α(C/EBPα)、过氧化物酶体增殖剂激活受体γ(PPARγ)和脂肪酸结合蛋白4(FABP4)基因的表达水平(P0.05);与对照组相比,t10,c12-CLA则抑制了C2C12肌细胞的生脂转分化,显著减少了细胞内TG含量(P0.05),显著下调了细胞内C/EBPα、PPARγ和FA BP4基因的表达水平(P0.05)。免疫印迹杂交结果显示FAS和FABP4的蛋白质表达水平也发生了与基因表达相一致的变化。2)与对照组相比,t10,c12-CLA抑制了C2C12肌细胞的生肌分化,显著减少了细胞内肌管数/细胞数(P0.05),显著下调了细胞内肌细胞生成素(MYOG)和成肌分化抗原(MYOD)基因的表达水平(P0.05);与对照组相比,c9,t11-CLA则显著上调了细胞内MYOG基因的表达水平(P0.05),对C2C12肌细胞的生肌分化有一定程度的促进作用。免疫印迹杂交结果显示MYOG和MYOD的蛋白质表达水平也发生了与基因表达相一致的变化。以上结果表明,CLA对动物骨骼肌细胞的正常生肌分化和生脂转分化都具有重要的调节作用。     

中棉所12(Gossypium hirsutum C.V.Zhongmian 12)体细胞胚发生及植株再生

通过对不同外植体的研究,发现幼胚下胚轴是理想的外植体材料,２,４－Ｄ和ＺＴ是中棉所１２体细胞胚发生的关键植物生长调节物。从愈伤组织诱导到大量再生植株只需４个月左右的时间。     

日粮中无机钴添加量对山羊瘤胃液及血清中VB12含量的影响

选３ 只健康白山羊,手术安装瘤胃瘘管后,在日粮中添加不同量的硫酸钴,研究钴的不同添加量对山羊瘤胃微生物ＶＢ１２ 合成量的影响。试验共分４ 期：对照期（ 饲喂基础日粮）;试验１ 期（ 基础日粮＋ 钴０ ．３ ｍｇ／ｋｇ） ;试验２ 期（ 基础日粮＋ 钴０ ．５ ｍｇ／ｋｇ） ;试验３ 期（ 基础日粮＋ 钴０ ．８ ｍｇ／ｋｇ）。每期定时采取瘤胃内容物和血液样品,测定瘤胃液和血清中ＶＢ１２ 的含量。试验结果为：各期瘤胃液中ＶＢ１２ 平均含量（ｎｇ／ｍｌ） 分别为：７ ．４６,１４ ．８５,５２．８６ ,２６ ．１４ ;各期血清中ＶＢ１２ 平均含量（ｎｇ／ｍｌ）分别为：１ ．６６ ,３ ．５９ ,３．９２,４．１８。试验结果表明：在本试验条件下,随着日粮中钴量的增加,血清中ＶＢ１２ 含量随之上升,试验各期与对照期差异极显著（ Ｐ＜ ０．０１） 。证实了日粮中一定范围内的钴添加量与瘤胃液和血清中ＶＢ１２ 含量有较高的相关性     

两种大眼蟹线粒体12S rRNA基因序列的比较研究

测定了宽身大眼蟹和日本大眼蟹线粒体12S rRNA基因部分片段的序列,前者为577 bp, 后者为572 bp.二者的核苷酸序列A、T、G、C的含量相似,分别为39.0%、35.7%、16.5%、8.8%;39.3%、 36.2%、 15.8%、8.7%;不包括11处插入/缺失位点,两序列间有75个变异位点,核苷酸差异率为13.18%,其中转换42个、颠换33个, 转换与颠换比约为1.3.对国内外4种大眼蟹长度为331 bp的12S rRNA基因同源序列进行分析,A+T的平均含量为76.6%,明显高于G+C的平均含量,且存有变异位点52个,简约信息位点25个.系统发生树的拓扑结构显示,所有的大眼蟹聚为一支,支持大眼蟹类为一单系.