牛布鲁氏菌A19突变株的构建及在BALB/c鼠中的免疫保护评估北大核心CSCD

【目的】构建牛布鲁氏菌A19-ΔVirB12突变株并免疫BALB/c鼠,初步评估了其免疫保护效果。【方法】应用PCR方法扩增A19疫苗株VirB12基因的上下游同源臂序列,构建重组质粒pBK-CMV-SacBVirB12,将该质粒电击转化至布鲁氏菌A19感受态细胞中,筛选得到布鲁氏菌疫苗株A19的VirB12基因缺失株。以A19疫苗株为参照,应用A19-ΔVirB12疫苗接种BALB/c小鼠,免疫45d后布鲁氏菌2308强毒株攻毒,攻毒15d后取BALB/c鼠的脾脏进行克脾指数测定和病理组织学检测。Western-blotting鉴定VirB12蛋白的免疫反应性。【结果】构建了牛布鲁氏菌A19-ΔVirB12突变株,小鼠免疫攻毒后15d,A19-ΔVirB12免疫组和A19免疫组的克脾指数与对照组之间有显著性差异(P<0.05)。A19免疫组与A19-ΔVirB12免疫组之间克脾指数差异不显著(P>0.05)。Western blotting实验表明VirB12蛋白具有免疫反应性。【结论】牛布鲁氏菌A19-ΔVirB12突变株与亲本株A19免疫保护性无明显差异,通过血清学方法可区分疫苗免疫与野生型牛种布鲁氏菌(Brucella abortus)感染动物,具备作为标记疫苗的潜力。     

Oxidized fatty acid analysis by charge-switch derivatization,selected reaction monitoring,and accurate mass quantitation

A highly sensitive, specific, and robust method for the analysis of oxidized metabolites of linoleic acid (LA), arachidonic acid (AA), and docosahexaenoic acid (DHA) was developed using charge-switch derivatization, liquid chromatography–electrospray ionization tandem mass spectrometry (LC–ESI MS/MS) with selected reaction monitoring (SRM) and quantitation by high mass accuracy analysis of product ions, thereby minimizing interferences from contaminating ions. Charge-switch derivatization of LA, AA, and DHA metabolites with N-(4-aminomethylphenyl)-pyridinium resulted in a 10- to 30-fold increase in ionization efficiency. Improved quantitation was accompanied by decreased false positive interferences through accurate mass measurements of diagnostic product ions during SRM transitions by ratiometric comparisons with stable isotope internal standards. The limits of quantitation were between 0.05 and 6.0 pg, with a dynamic range of 3 to 4 orders of magnitude (correlation coefficient r² > 0.99). This approach was used to quantitate the levels of representative fatty acid metabolites from wild-type (WT) and iPLA₂γ^–/– mouse liver identifying the role of iPLA₂γ in hepatic lipid second messenger production. Collectively, these results demonstrate the utility of high mass accuracy product ion analysis in conjunction with charge-switch derivatization for the highly specific quantitation of diminutive amounts of LA, AA, and DHA metabolites in biologic systems.     

Recurrent genome duplication events likely contributed to both the ancient and recent rise of ferns

Ferns, the second largest group of vascular plants, originated ～400 mil ion years ago(Mya). They became dominant in the ancient Earth landscape before the angiosperms and are stil important in current ecosystems.Many ferns have exceptional y high chromosome numbers,possibly resulting from whole-genome duplications(WGDs).However, WGDs have not been investigated molecularly across fern diversity. Here we detected and dated fern WGDs using a phylogenomic approach and by calculating synonymous substitution rates(Ks). We also investigated a possible correlation between proposed WGDs and shifts in species diversification rates. We identified 19 WGDs: three ancient events along the fern phylogenetic backbone that are shared by 66%–97% of extant ferns, with additional lineage-specific WGDs for eight orders, providing strongevidence for recurring genome duplications across fern evolutionary history. We also observed similar Ks peak values for more than half of these WGDs, with multiple WGDs occurring close to the Cretaceous(～145–66 Mya). Despite the repeated WGD events, the biodiversity of ferns declined during the Cretaceous, implying that other factors probably contributed to the floristic turnover from ferns to angiosperms. This study provides molecular evidence for recurring WGDs in ferns and offers important clues to the genomic evolutionary history of ferns.     

2000-2017年秦岭山地植被物候变化特征及其南北差异

气候变化背景下开展山地过渡带植被物候变化规律及区域差异研究对于揭示过渡带对气候变化的响应方式具有重要意义。基于2000-2017年MODIS EVI₂数据,反演了秦岭山地植被物候参数并建立了遥感物候数据集,分析了近18年来秦岭山地植被物候变化的时空特征及其南北差异。结果表明：①秦岭山地植被物候变化表现出明显的地形和气候地域分异规律,尤以高海拔区的变化最为显著,全区GSS （物候始期）主要发生于70-130DOY （Day of Year）,83.29%的区域呈提前趋势,提前主要集中在0-5d/10a （44.46%）与5-10d/10a （28.60%）;GSE （物候末期）主要发生于270-310DOY,50.17%的区域呈推迟趋势,变化趋势不明显;GSL （生长期）集中在150-210d,65.34%的区域呈延长趋势,延长在0-5d/10a （19.28%）、5-10d/10a （20.71%）及10-15d/10a （14.12%）均有分布。②秦岭山地GSS对气候变化的响应程度显著大于GSE,南北坡植被物候变化不仅存在区域差异且存在季节差异,GSS北坡较南坡平均约早6.2d且南坡提前趋势较北坡显著,GSE南坡较北坡平均约晚5.8d且北坡推迟趋势较南坡显著,GSL北坡较南坡约长18.7-23.2d。③GSS、GSS及GSS变化表现出显著的海拔敏感性,随着海拔上升,GSS逐渐推迟,GSE逐渐提前,GSL逐渐缩短,三者在海拔≤600m及≥2700m地区随海拔变化的波动幅度较大,南北坡三者随海拔的变化亦存在明显的差异,海拔每上升100m,北坡GSS推迟1.76d,GSE提前0.25d,GSL缩短2.01d;南坡GSS推迟1.50d,GSE提前0.44d,GSL缩短1.94d。④不同植被垂直带上GSS、GSE及GSL的变化存在明显差异,尤以≤600m植被带上及高山灌丛草甸带上的差异最为明显,且三者在高山灌丛草甸带的发生时间及时长北坡与南坡发生转换,表现为GSS、GSE、GSL北坡较南坡分别平均早3.5d、晚2.9d、长6.4d。     

黄淮海玉米生产能源利用效率和净生态系统碳平衡时空特征

黄淮海地区是我国重要的玉米产区之一,定量化该区域玉米生产的能源利用效率和净生态系统碳平衡对提高资源利用效率和实现碳中和具有重要意义。基于国家统计数据,利用生命周期评价(LCA)、能值分析和碳平衡等方法,定量化了2004-2018年黄淮海地区(包括河北、河南、山东、安徽和江苏5个省)玉米生产的能源利用效率和净生态系统碳平衡,并阐明其时空变化特征。结果表明:黄淮海地区玉米生产的平均能源利用效率、温室气体排放量、净生态系统碳平衡和可持续性指数分别为3.9、3.8 t CO₂-eq/hm²、12.6 t C/hm²和6.8。不同年份间黄淮海地区玉米生产的能源利用效率和净生态系统碳平衡存在显著差异,能源利用效率在2012年最高,为4.3,在2005和2007年最低,为3.7;净生态系统碳平衡在2015年最高,为14.2 t C/hm²,在2005年最低,为10.1 t C/hm²。各省份中以河北省玉米生产的能源利用效率、净生态系统碳平衡和可持续性指数最高,分别高于区域平均15.3%、9.6%和26.4%,较最低的江苏省高45.5%、22.0%和88.8%。河北省、河南省和山东省的综合得分均为正值,具有较高的资源利用效率和生态环境效益。黄淮海地区玉米生产资源投入、能源利用效率、生态环境效益和净生态系统碳平衡在时空尺度上存在较大的差异,应制定区域特异性优化管理策略,减少化肥和农药的施用,施用增效肥料和高效生物农药等,采用秸秆还田等保护性耕作措施,积极推进规模化和机械化的发展,实现黄淮海地区玉米生产的绿色可持续发展。     

喀斯特森林不同演替阶段植物群落物种多样性、功能性状、化学计量及其关联

探讨森林植物群落物种多样性、功能性状与化学计量特征及其内在关联,有助于构建结构-性状-功能的研究脉络,深入理解生态系统的过程与功能,为群落结构优化配置和调控提供科学依据。以贵州喀斯特高原峡谷区森林草灌、灌木、灌乔和乔木4个演替阶段的植物群落为对象,通过群落学调查和植物功能性状、生态化学计量测度,研究其物种多样性、功能性状和化学计量特征及其互作关系。结果表明:(1)乔木阶段的Shannon-Wiener指数与Pielou均匀度指数均为最高,依次达8.62、2.41,表明伴随着群落演替,物种分布的均匀程度增加。(2)植物群落物种多样性指数之间仅Margalef丰富度指数与Simpson优势度指数未呈显著相关(-0.644),其余均为显著或极显著相关关系,表明物种多样性指数之间存在较强的促进或抑制作用。(3)叶片厚度与其余指标,以及群落物种多样性指数与功能性状、化学计量之间均未呈显著相关,比叶面积(SLA)仅与土壤N∶P呈显著正相关(0.742),表明群落物种多样性、功能性状和生态化学计量特征之间的相关性较弱。(4)SLA为灌木阶段的272.13 cm2/g为最大,δ13C值在演替后期略高,草灌、灌木阶段倾向于受N、P共同限制,说明随演替进展,植物的适应策略和资源利用对策等均发生了一定的调整,表明植物和环境之间存在较强的协变关系。(5)该区森林培育时,应构建完整的乔木、灌木和草本层片,提高生态系统对养分矿化、转化和循环等的自调控能力。