一个甲基转移酶基因lomo3在洛蒙真菌素生物合成途径中的功能

【目的】洛蒙真菌素是在洛蒙德链霉菌(Streptomyces lomondensis)中生物合成的一种具有广谱抑菌活性的吩嗪类抗生素,但其合成机理仍不清晰。在洛蒙德链霉菌S015的洛蒙真菌素生物合成核心基因簇下游,有一甲基转移酶基因——lomo3,研究该基因对洛蒙真菌素生物合成的影响。【方法】对lomo3基因进行无痕敲除得到基因缺失突变株S015Δlomo3,再过表达重组质粒构建回补突变株S015Δlomo3::lomo3,比较两株突变株与野生型S015的发酵产物的变化。【结果】发现基因缺失菌株S015Δlomo3不能合成洛蒙真菌素,而基因回补菌株S015Δlomo3::lomo3则可恢复洛蒙真菌素的合成能力。【结论】甲基转移酶基因lomo3在洛蒙真菌素生物合成过程中起着重要的作用,但该基因的具体功能还有待深入研究。研究对于阐明洛蒙真菌素的生物合成途径具有一定的指导作用。     

城镇化背景下深圳典型流域鱼类群落特征及驱动因子

理解城镇的快速发展对河流鱼类群落结构的影响,是城镇河流科学管理和生物多样性保护的关键基础。本研究于2019年丰水期（8月）和枯水期（11月）,选取我国城镇化典型城市-深圳域内两个处于不同城镇化程度的代表性流域,应用多重统计方法比较分析了流域间鱼类群落结构的差异,并探讨了驱动鱼类群落变异的关键环境要素。结果发现,城镇化程度高的观澜河流域其鱼类种类组成、优势类群、生物多样性指数与城镇化程度低的坪山河流域有明显差别。 具体表现为：城镇化程度高的流域土著敏感种类如异鱲、吸鳅等几近消失,优势类群为外来入侵耐受种类,其物种多样性显著低于城镇化程度低的流域（P<0.05）。同时,外来鱼类在城镇河段其数量占比平均达92.5%,广泛分布于深圳城镇河流中。在环境因素方面,城镇化程度高的观澜河流域水体理化指标总氮、总磷、氨氮、化学需氧量、生化需氧量、高锰酸盐指数均显著性高于城镇化程度低的坪山河流域（P<0.05）。基于Bray-Curtis距离的冗余分析显示：城镇用地占比和总氮是影响观澜河和坪山河流域鱼类群落差异的主要因素。城镇化进程中河流生境的改变已影响到土著鱼类的生物多样性。因此,推动以恢复土著鱼类生物多样性的河流生态治理与保护是今后水生态目标管理的重要方向。     

枸杞SWEET基因家族的鉴定与糖含量关系分析

【目的】糖外排转运蛋白（sugars will eventually be exported transporters, SWEETs）在植物生长发育过程中发挥重要作用,为解析SWEETs基因在枸杞（Lycium barbarum L.）果实发育过程中对糖积累作用,进一步为揭示SWEET基因在枸杞果实发育过程中作用提供参考。【方法】研究基于枸杞基因组数据,采用生物信息学方法对枸杞SWEET基因（LbaSWEET）进行全基因组鉴定,并利用已发表的转录数据分析了LbaSWEETs在果实发育时期的基因表达情况。【结果】结果表明,枸杞SWEET基因家族共有37个成员,随机分布于10条染色体上,分别编码152~621个氨基酸,蛋白质分子量为16.87~69.97 kD,等电点为4.96~9.86。亚细胞定位预测位于叶绿体或质膜,大多数含有7个跨膜螺旋。系统进化分析发现,37个LbaSWEET蛋白可分为4个亚群,每个亚群的基因结构和保守基序组成相似。启动子元件分析发现,LbaSWEET基因启动子富含大量激素响应、逆境胁迫和生长发育响应元件。转录组数据和qRT-PCR分析表明,LbaSWEET9和LbaSWEET29基因表达量随着果实成熟呈现显著增加。相关性分析结果表明,LbaSWEET9和LbaSWEET29基因表达量与果糖含量呈显著正相关。【结论】研究推测LbaSWEET9和LbaSWEET29基因是果糖积累的关键基因。     

母乳微生物及其对婴幼儿健康影响的研究进展

母乳是新生儿最佳的营养来源,不仅提供丰富的营养物质,还能通过自身独特的微生物群影响新生儿肠道细菌的初始定植和机体健康。培养法和基因组测序法均揭示了母乳微生物的多样性和稳定性,除双歧杆菌和乳杆菌外,母乳中还含有多种潜在的益生菌。人乳低聚糖（human milk oligosaccharides,HMOs）是母乳中仅次于乳糖和脂类的第三丰富的营养物质。作为一种天然益生元,HMOs可以选择性地促进有益细菌的生长,从而在促进母乳喂养婴幼儿健康发育方面起着关键作用。本文总结了母乳中微生物的种类、来源、哺乳期间的变化及其与HMOs之间的关系,讨论了母乳微生物对婴幼儿健康的潜在影响,包括抑制病原体入侵肠道、促进免疫系统发育、调节婴幼儿代谢和改善早期认知发育等,以期为母乳源益生菌的开发提供理论指导。

     

New pyrrolo[3,2-b]pyrroles with AIE characteristics for detection of dichloromethane and chloroform

Three new pyrrolo[3,2-b]pyrrole derivatives containing methoxyphenyl, pyrene or tetraphenylethylene (TPE) units (compounds 1 – 3) have been designed, synthesized and fully characterized. The aggregation-induced emission (AIE) properties of compounds 1 – 3 were tested in different water fraction (f_w) of tetrahydrofuran (THF). The pyrrolo[3,2-b]pyrrole derivative 3 containing TPE units exhibited typical AIE features with an enhanced emission (∼32-fold) in the solid state versus in solution; compounds 1 and 2 exhibited an aggregation-caused quenching effect. In addition, the steric and electronic effects of the peripheral moieties on the emission behavior, both in solution and in the solid state, have been investigated. Moreover, pyrrolo[3,2-b]pyrrole 1 exhibits high sensitivity and selectivity for dichloromethane and chloroform solvents, with the system displaying a new emission peak and fast response time under ultraviolet irradiation.     

Multi-Shell Copper Catalysts for Selective Electroreduction of CO2 to Multicarbon Chemicals

Electrocatalytic CO₂ reduction (CO₂R) coupled with renewable electricity has been considered as a promising route for the sustainability transition of energy and chemical industries. However, the unsatisfactory yield of desired products, particularly multicarbon (C₂₊) products, has hindered the implementation of this technology. This work describes a strategy to enhance the yield of C₂₊ product formation in CO₂R by utilizing spatial confinement effects. The finite element simulation results suggest that increasing the number of shells in the catalyst wil lead to a high local concentration of *CO and promotes the formation of C₂₊ products. Inspired by this, Cu nanoparticles are synthesized with desired hollow multi-shell structures. The CO₂ reduction results confirm that as the number of shells increase, the hollow multi-shell copper catalysts exhibit improved selectivity toward C₂₊ products. Specifically, the Cu catalyst with 4.4-shell achieved a high selectivity of over 80% toward C₂₊ at a current density of 900 mA cm⁻². Evidence from in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy unveils that the multi-shell Cu catalyst exhibits an enhanced *CO_atop coverage and the stronger interaction with *CO_atop compared to commercial Cu, confirming the simulation results. Overall, the work promises an effective approach for boosting CO₂R selectivity toward value-added chemicals.     

Inhibiting Dendrite Formation and Electrode Corrosion via a Scalable Self-Assembled Mercaptan Layer for Stable Aqueous Zinc Batteries

The practical use of Zn metal anodes in aqueous zinc batteries is impeded by the growth of dendrites, anode corrosion, and hydrogen evolution reaction in aqueous electrolytes. In this study, a simple, energy-efficient, and scalable approach is reported to mitigate these detrimental issues effectively. Using 1-hexanethiol (HT), a hydrophobic self-assembled mercaptan layer (SAML) with a highly ordered structure is in situ created on the surface of the Zn anode. This ultrathin interfacial structure guides uniform Zn deposition and shields the Zn anode from water and oxygen-induced corrosion, thus effectively inhibiting dendrite formation and side reactions. Consequently, the HT-Zn electrode showcases impressive electrochemical stability and reversibility, and the as-assembled HT-Zn||I₂ full cell delivers increased specific capacity (from 112 to 155 mAh g⁻¹ at 1 A g⁻¹) and ultra-stable cyclability (zero capacity decay during the extended 1500 cycles at 4 A g⁻¹). To validate the effectiveness of this simple and scalable method, a large-sized pouch cell is prepared, which can be stably operated for 1000 cycles with a capacity decay of merely 0.0098% per cycle and Coulombic efficiency exceeding 99.1%. The presented SAML strategy highlights the potential of molecular engineering in improving the performance of aqueous zinc batteries.     

Characterization and acceleration of genome shuffling and ploidy reduction in synthetic allopolyploids by genome sequencing and editing

Polyploidy and the subsequent ploidy reduction and genome shuffling are the major driving forces of genome evolution. Here, we revealed short-term allopolyploid genome evolution by sequencing a synthetic intergeneric hybrid (Raphanobrassica, RRCC). In this allotetraploid, the genome deletion was quick, while rearrangement was slow. The core and high-frequency genes tended to be retained while the specific and low-frequency genes tended to be deleted in the hybrid. The large-fragment deletions were enriched in the heterochromatin region and probably derived from chromosome breaks. The intergeneric translocations were primarily of short fragments dependent on homoeology, indicating a gene conversion origin. To accelerate genome shuffling, we developed an efficient genome editing platform for Raphanobrassica. By editing Fanconi Anemia Complementation Group M (FANCM) genes, homoeologous recombination, chromosome deletion and secondary meiosis with additional ploidy reduction were accelerated. FANCM was shown to be a checkpoint of meiosis and controller of ploidy stability. By simultaneously editing FLIP genes, gene conversion was precisely introduced, and mosaic genes were produced around the target site. This intergeneric hybrid and genome editing platform not only provides models that facilitate experimental evolution research by speeding up genome shuffling and conversion but also accelerates plant breeding by enhancing intergeneric genetic exchange and creating new genes.     

Intra‐amniotic mesenchymal stem cell therapy improves the amniotic fluid microenvironment in rat spina bifida aperta fetuses

ObjectivesSpina bifida aperta (SBA) is one of the most common neural tube defects. Neural injury in SBA occurs in two stages involving failed neural tube closure and progressive degeneration through contact with the amniotic fluid. We previously suggested that intra‐amniotic bone marrow‐derived mesenchymal stem cell (BMSC) therapy for fetal rat SBA could achieve beneficial functional recovery through lesion‐specific differentiation. The aim of this study is to examine whether the amniotic fluid microenvironment can be improved by intra‐amniotic BMSC transplantation.MethodsThe intra‐amniotic BMSC injection was performed using in vivo rat fetal SBA models. The various cytokine expressions in rat amniotic fluid were screened by protein microassays. Intervention experiments were used to study the function of differentially expressed cytokines.ResultsA total of 32 cytokines showed significant upregulated expression in the BMSC‐injected amniotic fluid. We focused on Activin A, NGF, BDNF, CNTF, and CXCR4. Intervention experiments showed that the upregulated Activin A, NGF, BDNF, and CNTF could inhibit apoptosis and promote synaptic development in fetal spinal cords. Inhibiting the activity of these factors weakened the anti‐apoptotic and pro‐differentiation effects of transplanted BMSCs. Inhibition of CXCR4 activity reduced the engraftment rate of BMSCs in SBA fetuses.ConclusionBMSC transplantation can improve the amniotic fluid environment, and this is beneficial for SBA repair.

In utero intra‐amniotic BMSC or PBS microinjection in the E15 fetuses was performed in E15 rat fetuses with spina bifida aperta, and amniotic fluid was collected at E21 for protein array detection. Venn diagram shows the relationship of three biological processes (GO: 0030335, 0048699, and 0043524) and the attribution of differentially expressed proteins. Comparative analysis of five proteins with the largest fold changes in the process of generation of neurons.