对氨基苯甲酸酯同系物形成细胞色素P_（450）代谢中间体络合物的定量结构与活性关系

细胞色素Ｐ４５０（Ｐ４５０,Ｅｃ１．１４．１４．１）是一种十分重要的催化氧化反应的酶。本文测定了１２个对氨基苯甲酸酯同系物与Ｐ４５０相互作用而形成Ｐ４５０代谢中间体络合物的活性,用半经验分子轨道法ＭＮＤＯ－ＰＭ３计算得到了这些同系物的分子轨道指数,并用逐步多元回归分析法导出了活性与分子轨道指数及正辛醇／水分配系数的对数值（ＬｏｇＰ）之间的定量结构与活性关系（ＱＳＡＲ）。结果表明：对氨基苯甲酸脂同系物形成Ｐ４５０代谢中间体络合物的活性与原子净电荷的绝对值之和（∑Ｑ）和ＬｏｇＰ均具有很好的抛物线型相务性,同时,ＬｏｇＰ与∑Ｑ之间也存在相当好的相关性。     

Human appropriation of net primary production as driver of change in landscape-scale vertebrate richness

Aim

Land use is the most pervasive driver of biodiversity loss. Predicting its impact on species richness (SR) is often based on indicators of habitat loss. However, the degradation of habitats, especially through land-use intensification, also affects species. Here, we evaluate whether an integrative metric of land-use intensity, the human appropriation of net primary production, is correlated with the decline of SR in used landscapes across the globe.

Location

Global.

Time period

Present.

Major taxa studied

Birds, mammals and amphibians.

Methods

Based on species range maps (spatial resolution: 20 km × 20 km) and an area-of-habitat approach, we calibrated a “species–energy model” by correlating the SR of three groups of vertebrates with net primary production and biogeographical covariables in “wilderness” areas (i.e., those where available energy is assumed to be still at pristine levels). We used this model to project the difference between pristine SR and the SR corresponding to the energy remaining in used landscapes (i.e., SR loss expected owing to human energy extraction outside wilderness areas). We validated the projected species loss by comparison with the realized and impending loss reconstructed from habitat conversion and documented by national Red Lists.

Results

Species–energy models largely explained landscape-scale variation of mapped SR in wilderness areas (adjusted R²-values: 0.79–0.93). Model-based projections of SR loss were lower, on average, than reconstructed and documented ones, but the spatial patterns were correlated significantly, with stronger correlation in mammals (Pearson's r = 0.68) than in amphibians (r = 0.60) and birds (r = 0.57).

Main conclusions

Our results suggest that the human appropriation of net primary production is a useful indicator of heterotrophic species loss in used landscapes, hence we recommend its inclusion in models based on species–area relationships to improve predictions of land-use-driven biodiversity loss.     

游荡型黄河滩涂植物群落多样性及种间联结性

黄河干流流量季节性变化和小浪底“调水调沙”形成了黄河河南段特殊的游荡型滩涂生态系统,为揭示游荡型黄河滩涂(嫩滩、二滩、高滩和大堤)群落组成和种间关系及群落稳定性规律,于2015年9月至2018年11月,采用典型样方法在郑州黄河湿地自然保护区游荡型黄河滩涂开展群落学调查,利用149个草本层样方分析群落物种组成、多样性、种间联结性和群落稳定性。结果表明：(1)研究区植物共有90科289属445种,其中被子植物87科286属440种,裸子植物2科2属3种;蕨类植物仅见1属2种。(2)不同滩涂生境优势种具有显著差异,且总体狗牙根(Cynodon dactylon)、芦苇(Phragmites australis)和小蓬草(Erigeron canadensis)为优势种,国家二级保护植物野大豆(Glycine soja)呈斑块聚集分布,且为嫩滩和二滩亚优势种。(3)大堤物种多样性各指标取值最大,嫩滩次之,二滩和高滩较小。(4)χ²检验、Jaccard指数、Pearson相关检验和Spearman秩相关检验表明,优势种种对种间联结性不强,各物种间相对独立。(5)二滩总体联结...     

宁夏河东沙区刺槐和丝绵木水分利用策略

刺槐和丝绵木混交林是宁夏河东沙区防护林建设的主要模式,了解刺槐和丝绵木的水分利用策略,能为区域植被恢复和防护林林分结构调整提供科学依据。以宁夏河东沙区刺槐(Robinia pseudoacacia)和丝绵木(Euonymus bungeanus)混交林为研究对象,通过监测微气象、树干液流和土壤质量含水量,结合大气降水、土壤水、植物木质部水同位素组成,采用Granier及其校正公式,运用贝叶斯混合模型(MixSIAR)和相似性比例指数(PS)研究2个树种的蒸腾耗水、水分来源和水分利用关系。结果表明：刺槐和丝绵木的蒸腾耗水量在生长季中期较高,前期和后期较小,刺槐的蒸腾耗水量是丝绵木的1.55倍;影响刺槐蒸腾耗水的主要环境因子为饱和水汽压差、太阳辐射、0—40 cm土壤质量含水量和40—120 cm土壤质量含水量;影响丝绵木蒸腾耗水的主要环境因子为饱和水汽压差、太阳辐射、平均气温、0—40 cm土壤质量含水量和40—120 cm土壤质量含水量;蒸腾耗水较高时,刺槐主要吸收利用中层土壤水,丝绵木主要吸收利用浅层土壤水,蒸腾耗水较低时,刺槐主要吸收利用浅层土壤水,丝绵木主要吸收利用中层土壤水;在...     

利用荧光SSR标记鉴定茶树自然杂交后代遗传背景

为研究茶树自然杂交后代遗传背景,分析不同茶树自然杂交后代遗传差异,本研究利用24对EST-SSR标记对82个茶树自然杂交后代和34个福建主要栽培品种进行分子标记,分析了茶树自然杂交后代的亲缘关系、群体遗传多样性、亲本模拟分析。结果表明：(1)24对SSR标记共检测到157个多态性位点,平均等位位点数为6.542个,Nei’s多样性指数平均为0.588,Shannon’s 信息指数平均为1.182,平均观测杂合度和期望杂合度分别为0.577和 0.591。(2)遗传距离聚类将个供试样品划分为4类,群体1主要为‘丹桂’及其自然杂交后代;群体2主要为‘丹桂’、‘黄观音’自然杂交后代与福建省乌龙茶品种;群体3主要为‘白鸡冠’及其自然杂交后代;群体4主要为福建省绿茶品种。(3)‘丹桂’、‘白鸡冠’、‘黄观音’自然杂交后代群体与福建主要栽培品种的遗传距离分别为0.079、0.117、0.107。(4)群体1亚群b内‘丹桂’自然杂交后代模拟亲本准确率为77.8%,模拟父本主要为福建乌龙茶品种,与群体2(亚群a)的遗传相似度、遗传分化系数、基因流分别为0.899、0.043、5.480。(5)AMOVA分析结果显示,有88.52%的遗传变异来自群体内部的个体间,表明遗传变异主要发生在群体内。     

Nucleotide Sequence Assessment of Four ORFs of Citrus Tristeza Virus: Evidence of Recombination

Citrus Tristeza Virus (CTV), usually occurs in nature as a mixture of genotypes. Six naturally infected citrus (Citrus sinensis) trees grafted on sour orange rootstock were collected from three citrus growing governorates in Egypt (Sharqia, Qalyubia and Garbia). In this study, RT-PCR, Single-Strand Conformation Polymorphism (SSCP) and nucleotide sequence analysis were used for four independent CTV genomic regions (p65, p18, p20, and p23) to detect and assess the sequence and genetic variabilities among CTV Egyptian isolates. RTPCR products (650 bp) for the CTV p23 gene obtained from the selected isolates were used for the SSCP analysis and DNA sequencing. SSCP patterns of p23 gene for individual isolates yielded different complex haplotype patterns. Nucleotide sequence analysis of p23 region amplified from six isolates under study revealed that p23 shared high nucleotide identity 98.7% with T36 isolate from USA, Florida. Phylogenetic analysis of p23 gene indicated a close evolutionary relationship between all examined isolates and Qaha isolate (T36 isolate group), suggesting that they may have originated from closely related ancestors. Nucleotide sequence analysis of the three genes located on CTV 3′-coterminal overhang, p18, p20 and p65, amplified from isolate A3, Sharqia governorate, revealed that the p18, p65, and p20 genes were related to the T3-KB isolate from South Africa with 99%–100% sequence homology. Phylogenetic relationship analysis for p65, p18 and p20 ORFs clustered the current A3 isolate with T3 genotype group. The recombination analysis identified three of six isolates from Sharqia, and Garbia as potential recombinant for p23 gene. The isolates T36 and T3 were identified as major donors for recombination events in isolate A3. Our results concluded that p23 ORF likely to be as a hotspot region for recombination and originated through recombination event. The current study indicated that recombination is an important factor for the origin of CTV strains in Egypt.     

基于拉曼技术的单细胞生长检测方法

目的 单细胞生长检测可以更加科学地揭示微生物代谢变化的规律,为后期微生物工程应用提供指导。针对微生物生长应用于食品安全期和最佳食用期的精准检测问题,本文提出一种基于拉曼技术的单细胞生长检测方法。方法 首先,通过同步培养实验采集了枯草芽孢杆菌两个批次共900个单细胞拉曼光谱（SCRS）数据,其中600个用于训练和测试,另一批次300个用于模型验证。其次,基于主成分分析的特征关系矩阵,提出CP-SP特征评估方法以筛选SCRS特征用于模型检测。再基于XGBoost构建检测模型,并应用网格搜索和交叉验证对检测模型进行调优。最后,应用混淆矩阵、ROC曲线评估模型对细胞滞后期、对数期和稳定期的检测准确率、敏感性和特异性。结果 选用CP-SP筛选的第一、第二和第四主成分较特征贡献率前3个主成分的分类性能提高了3.1%,调优后的细胞生长检测模型测试准确率为96.0%,验证准确率为92.3%。结论 基于拉曼技术的单细胞生长检测方法能准确识别单细胞生长状态且具有较高的泛化能力,可为食品安全和保鲜制定精准调控机制提供科学指导。     

安徽省清凉峰自然保护区植物区系的研究

清凉峰自然保护区有维管束植物181科,601属,1228种,是安徽植物资源集中地之一。区系成分起源古老,孑遗种多,保存着丰富的珍稀、濒危植物。种子植物区系地理成分复杂,各类热带成分、温带成分、中国特有成分分别占本区种子植物属总数的33.6%、62.96%、3.44%,显示了本区植物区系的亚热带特性。本区植物区系97.6%的成分与华东植物区系共有,且含华东特有种111种,具有典型华东植物区系特征。本区植物区系与西天目山、黄山植物区系关系最密切,其次为大别山和庐山,再次为神农架。     

天然产物抗氧化构效关系及作用机理的研究概况

本文简介了近十年来天然抗氧化剂的研究概况,讨论了天然产物抗争氧化活性的构效关系及作用机理。