The complex genome and adaptive evolution of polyploid Chinese pepper (Zanthoxylum armatum and Zanthoxylum bungeanum)

Zanthoxylum armatum and Zanthoxylum bungeanum, known as ‘Chinese pepper’, are distinguished by their extraordinary complex genomes, phenotypic innovation of adaptive evolution and species-special metabolites. Here, we report reference-grade genomes of Z. armatum and Z. bungeanum. Using high coverage sequence data and comprehensive assembly strategies, we derived 66 pseudochromosomes comprising 33 homologous phased groups of two subgenomes, including autotetraploid Z. armatum. The genomic rearrangements and two whole-genome duplications created large (~4.5 Gb) complex genomes with a high ratio of repetitive sequences (>82%) and high chromosome number (2n = 4x = 132). Further analysis of the high-quality genomes shed lights on the genomic basis of involutional reproduction, allomones biosynthesis and adaptive evolution in Chinese pepper, revealing a high consistent relationship between genomic evolution, environmental factors and phenotypic innovation. Our study provides genomic resources and new insights for investigating diversification and phenotypic innovation in Chinese pepper, with broader implications for the protection of plants under severe environmental changes.     

谷氨酸棒杆菌代谢工程高效生产L-缬氨酸北大核心CSCD

L-缬氨酸作为一种支链氨基酸,广泛应用于医药和饲料等领域。本研究借助多种代谢工程策略相结合的方法,构建了生产L-缬氨酸的微生物细胞工厂,实现了L-缬氨酸的高效生产。首先,通过增强糖酵解途径、减弱副产物代谢途径相结合的方式,强化了L-缬氨酸合成前体丙酮酸的供给;其次,针对L-缬氨酸合成路径关键酶—乙酰羟酸合酶进行定点突变,提高了菌株的抗反馈抑制能力,并利用启动子工程策略,优化了路径关键酶的基因表达水平;最后,利用辅因子工程策略,改变了乙酰羟酸还原异构酶和支链氨基酸转氨酶的辅因子偏好性,由偏好NADPH转变为偏好NADH,从而提高了L-缬氨酸的合成能力。在5L发酵罐中,最优谷氨酸棒杆菌工程菌株Corynebacterium glutamicum K020的L-缬氨酸产量、得率和生产强度分别达到了110g/L、0.51g/g和2.29 g/(L·h)。     

基于碳酸酐酶IX的肿瘤成像和治疗研究进展

碳酸酐酶IX (carbonic anhydrase IX, CAIX)是一种在乏氧肿瘤细胞表面特异性过表达的跨膜蛋白,具有调节肿瘤细胞内外酸碱度的功能,与肿瘤增殖、侵袭和转移息息相关。因此,CAIX是一个很有潜力的肿瘤成像和治疗靶点。本文详细阐述了基于CAIX的肿瘤成像、治疗和诊疗一体化的研究进展,并对CAIX作为抗肿瘤靶点的应用前景进行了展望。     

大白菜NHX基因家族的鉴定与表达分析

Na+/H+逆向转运蛋白(Na+/H+antiporter,NHX)基因家族在植物响应盐胁迫中发挥重要作用。本研究鉴定了大白菜NHX基因家族成员,并分析了大白菜NHX基因(Brassica rapa ssp.Pekinensis NHX,BrNHXs)响应高温、低温、干旱和盐胁迫等非生物逆境的表达模式。结果表明,在大白菜中共鉴定到9个NHX基因家族成员,分布在大白菜的6条染色体上,其氨基酸数目在513–1154 aa之间,相对分子量集中在56804.22–127856.66 kDa,等电点位于5.35–7.68之间。该基因家族成员主要存在于液泡中,基因结构完整,外显子的数目介于11–22之间。大白菜NHX基因家族编码的蛋白质二级结构都具有α-螺旋、β-转角和不规则卷曲结构,其中α-螺旋发生频率较高。实时荧光定量PCR(quantitative real-time PCR,qRT-PCR)分析显示,该基因家族成员在高温、低温、干旱和盐胁迫下均有不同程度地响应,且在不同时间表达差异显著。以BrNHX02和BrNHX09对这4种胁迫的响应最为显著,表达量在处理72 h时均显著上调,可作为候选基因进一步验证其功能。     

Metabolic engineering of Mannheimia succiniciproducens for malic acid production using dimethylsulfoxide as an electron acceptor

Microbial production of various TCA intermediates and related chemicals through the reductive TCA cycle has been of great interest. However, rumen bacteria that naturally possess strong reductive TCA cycle have been rarely studied to produce these chemicals, except for succinic acid, due to their dependence on fumarate reduction to transport electrons for ATP synthesis. In this study, malic acid (MA), a dicarboxylic acid of industrial importance, was selected as a target chemical for mass production using Mannheimia succiniciproducens, a rumen bacterium possessing a strong reductive branch of the TCA cycle. The metabolic pathway was reconstructed by eliminating fumarase to prevent MA conversion to fumarate. The respiration system of M. succiniciproducens was reconstructed by introducing the Actinobacillus succinogenes dimethylsulfoxide (DMSO) reductase to improve cell growth using DMSO as an electron acceptor. Also, the cell membrane was engineered by employing Pseudomonas aeruginosa cis-trans isomerase to enhance MA tolerance. High inoculum fed-batch fermentation of the final engineered strain produced 61 g/L of MA with an overall productivity of 2.27 g/L/h, which is the highest MA productivity reported to date. The systems metabolic engineering strategies reported in this study will be useful for developing anaerobic bioprocesses for the production of various industrially important chemicals.     

Phosphorylation states greatly regulate the activity and gating properties of Cav3.1 T-type Ca2+ channels

Ca_v3.1 T-type Ca²⁺ channels play pivotal roles in neuronal low-threshold spikes, visceral pain, and pacemaker activity. Phosphorylation has been reported to potently regulate the activity and gating properties of Ca_v3.1 channels. However, systematic identification of phosphorylation sites (phosphosites) in Ca_v3.1 channel has been poorly investigated. In this work, we analyzed rat Ca_v3.1 protein expressed in HEK-293 cells by mass spectrometry, identified 30 phosphosites located at the cytoplasmic regions, and illustrated them as a Ca_v3.1 phosphorylation map which includes the reported mouse Ca_v3.1 phosphosites. Site-directed mutagenesis of the phosphosites to Ala residues and functional analysis of the phospho-silent Ca_v3.1 mutants expressed in Xenopus oocytes showed that the phospho-silent mutation of the N-terminal Ser18 reduced its current amplitude with accelerated current kinetics and negatively shifted channel availability. Remarkably, the phospho-silent mutations of the C-terminal Ser residues (Ser1924, Ser2001, Ser2163, Ser2166, or Ser2189) greatly reduced their current amplitude without altering the voltage-dependent gating properties. In contrast, the phosphomimetic Asp mutations of Ca_v3.1 on the N- and C-terminal Ser residues reversed the effects of the phospho-silent mutations. Collectively, these findings demonstrate that the multiple phosphosites of Ca_v3.1 at the N- and C-terminal regions play crucial roles in the regulation of the channel activity and voltage-dependent gating properties.     

肠道菌群在脊髓损伤后胃肠道炎症反应中的研究进展

脊髓损伤(spinal cord injury, SCI)目前尚无有效的治疗手段。脊髓损伤后,患者常伴有严重的胃肠功能障碍,严重影响患者的生活质量。研究发现,脊髓损伤后肠道菌群的紊乱和脊髓损伤后的胃肠道功能障碍密切相关。因此,本文围绕脊髓损伤后肠道菌群的变化,探讨肠道菌群在迷走神经、下丘脑-垂体-肾上腺和肠道菌群代谢物3个途径中发挥的作用,及与胃肠道炎症反应相关的研究进展。     

信号分子在生物脱氮中的作用及检测方法

生物脱氮是由微生物主导的地球氮循环中的重要环节之一,主要包括硝化、反硝化和厌氧氨氧化(anaerobic ammonium oxidation,anammox)等过程。在微生物联合作用下,污水中的有机氮及氨氮经一系列作用转化为氮气,这种经济高效、环境友好的处理工艺在世界范围内得到广泛应用。群体感应(quorum sensing,QS)以信号分子为媒介通过改变菌群密度和周围环境变化来调节微生物的各种行为。大量的研究已证实调控QS信号分子在生物脱氮中具有应用潜力。本文介绍了各种信号分子类型,从基因组学、实际应用等方面综述了各类信号分子以及检测方法,同时针对酰基高丝氨酸内酯(acyl homoserine lactones,AHLs)类信号分子在生物脱氮中的作用进行详细介绍。然而不足之处在于信号分子研究只是停留在实验室阶段,仅仅研究了单一信号分子对生物脱氮的影响。未来可将信号分子应用于实际污水,研究多种信号分子共同作用以及多种微生物之间的QS现象。     

儿童最大有氧活动能力的发展特征

本文报告了我国４６３名１０－１９岁儿童青少年的最大有氧活动能力的发展特征。在青春早期,男女童的最大吸氧量绝对值均随年龄增长而增加,男童由１．７５升／分增至３．１０升／分,女童由１．４４升／分增至２．０７升／分,女童增长较少;以后女童即稳定于这一水平,男童仍略有增长。按身高及按最大心率计标的相对值与其有相似的特征。按体重和瘦体重计算的相对值,在男女童都未见随年龄增长的规律。男童ＶＯ２ｍａｘ绝对值及各