极端耐盐碱菌株的筛选及其菌肥对盐碱条件下小麦生长和土壤环境的影响

为获得具有盐碱地改良应用潜力的耐盐碱菌株,将采集于东营盐碱地的土样稀释涂布于pH 9、盐浓度100 g·L-1的Gibbson改良培养基上,共获得18株细菌.通过提高盐浓度、pH值,最终获得在pH 12、盐浓度20%的条件下仍然可以生长的极端耐盐碱菌株N14.对N14进行形态学、生理生化特征和16S rDNA序列分析鉴定,结果表明:菌株N14为马氏芽孢杆菌.盆栽试验结果表明,与盐碱土(CK)相比,N14菌肥可以显著提高小麦的生物量,株高、鲜重、干重分别提高了21.8%、57.9%、41.7%;显著增加小麦叶绿素a、叶绿素b、叶绿素总量,增长率分别为36.4%、20.0%、31.7%;显著提高盐碱土壤中的蔗糖酶、脲酶和碱性磷酸酶的活性,增长率分别为23.2%、68.8%、106.5%;显著提高小麦根系的超氧化物歧化酶、过氧化物酶和过氧化氢酶的活性,增长率分别为109.6%、17.8%、50%;显著减少小麦根系丙二醛的含量,减少率为39.8%.本研究为极端耐盐碱菌的应用提供了一条新思路,为盐碱地的改良提供了一条新途径.     

二氧化碳人工生物转化

二氧化碳(carbon dioxide, CO₂)资源化利用是全球可持续发展面临的巨大挑战。自然界生物固碳绿色环保,但能效低、速度慢,难以满足工业生产需求;物理化学固碳效率高,但能耗高、产品单一,如何结合生物、物理与化学技术优势,以二氧化碳为原料进行生物转化利用是当前迫切需要解决的科技难题。本文结合中国科学院天津工业生物技术研究所建所10年来的发展,综述了人工固碳元件、途径与系统的设计与构建等前沿基础领域取得的重要进展,特别是首次实现二氧化碳人工合成淀粉,并对建立二氧化碳人工生物转化技术体系进行了展望。相关进展与展望为助力实现“碳达峰、碳中和”目标提供了新思路。     

正常人耵聍中马拉色菌菌种构成研究

目的研究正常人耵聍中马拉色菌菌种构成及同一宿主耵聍中菌种是否一致。方法采集45名健康志愿者双侧耵聍,0.1%曲拉通X-100溶解稀释后接种于含菜籽油培养基,生化及形态学方法鉴定到种,同时提取菌种DNA,用真菌通用引物ITS1/ITS4做PCR扩增并测序鉴定。结果有44例(97.78%)双侧耵聍中均培养出马拉色菌(共分离出88株菌),菌种构成:糠粃马拉色菌29株(32.95%)、斯洛菲马拉色菌23株(26.14%)、合轴马拉色菌18株(20.45%)、球形马拉色菌11株(12.50%)、限制性马拉色菌7株(7.95%)。44例(88株菌)中双侧耵聍菌种相同者有38例(76株菌)(一致率86.36%)。结论正常人耵聍中马拉色菌菌种分布较广,主要菌种为糠秕马拉色菌。同一宿主双侧耵聍中马拉色菌菌种具有一定的一致性。     

“氯敌鼠”防治对农田小哺乳动物群落结构的影响及群落演替分析

对不同防治对策下施用氯敌鼠作为杀鼠剂对农田小哺乳动物群落结构的影响进行了研究．结果表明,杀鼠剂对群落组成有很大影响,灭鼠时机、灭鼠次数不同,群落的反应也不同．秋季灭鼠,小哺乳动物数量逐年下降,３ 年后可达到较低密度．群落多样性也逐年下跌,且回升极弱．春季灭鼠,数量可持续在低水平,群落多样性较其它处理高,对化学灭鼠破坏的生物多样性有较强的恢复力．灭鼠频次的增加对小哺乳动物总体数量降低有强化作用．可以认为,化学灭鼠明显地降低了群落中小哺乳动物的密度,也降低了群落的多样性．促使小哺乳动物群落向着优势种突出、种类单调、群落稳定性差的方向演替．     

Highly efficient and inducible DNA excision in transgenic silkworms using the FLP/<Emphasis Type="Italic">FRT</Emphasis> site-specific recombination system

Efficient and inducible recombinase-mediated DNA excision is an optimal technology for automatically deleting unwanted DNA sequences, including selection marker genes. However, this methodology has yet to be established in transgenic silkworms. To achieve efficient and inducible FLP recombinase-mediated DNA excision in transgenic silkworms, one transgenic target strain (TTS) containing an FRT-flanked silkworm cytoplasmic actin 3 gene promoter (A3)-enhanced green fluorescent protein (EGFP) expression cassette, as well as two different types of FLP recombinase expression helper strains were generated. Then, the FLP recombinase was introduced into the TTS silkworms by pre-blastoderm microinjection and sexual hybridization. Successful recombinase-mediated deletion of the A3-EGFP expression cassette was observed in the offspring of the TTS, and the excision efficiencies of the FLP expression vector and FLP mRNA pre-blastoderm microinjection were 2.38 and 13.3 %, respectively. The excision efficiencies resulting from hybridization between the TTS and the helper strain that contained a heat shock protein 70 (Hsp70)-FLP expression cassette ranged from 32.14 to 36.67 % after heat shock treatment, while the excision efficiencies resulting from hybridization between the TTS and the helper strain containing the A3-FLP expression cassette ranged from 97.01 to 100 %. These results demonstrate that the FLP/FRT system can be used to achieve highly efficient and inducible post-integration excision of unwanted DNA sequences in transgenic silkworms in vivo. Our present study will facilitate the development and application of the FLP/FRT system for the functional analysis of unknown genes, and establish the safety of transgenic technologies in the silkworm and other lepidopteran species.     

CTSB promotes porcine preadipocytes differentiation by degrading fibronectin and attenuating the Wnt/β-catenin signaling pathway

The process of preadipocytes differentiation plays a vital role in adipose tissue expansion and many factors are involved in this event. Cathepsin B (CTSB), secreted from lysosome, has been reported in regulating a variety of physiological processes. In this study, we demonstrated CTSB promotes lipid accumulation and adipogenic genes expression in porcine primary preadipocytes by degrading fibronectin (Fn), a key component of extracellular matrix. Lithium chloride (LiCl) is an activator of Wnt/β-catenin signaling through stabilizing β-catenin. We found that CTSB can relieve the anti-adipogenic effects of LiCl, indicating that CTSB could impact Wnt/β-catenin signaling pathway. Interestingly, Fn is an important target gene of Wnt/β-catenin. So we considered that CTSB promote preadipocytes differentiation by suppressing these two pathways.     

CXCR4 is a major chemokine receptor on glioma cells and mediates their survival

Chemokines were described originally in the context of providing migrational cues for leukocytes. They are now known to have broader activities, including those that favor tumor growth. We addressed whether and which chemokines may be important promoters of the growth of the incurable brain neoplasm, malignant gliomas. Analyses of 16 human glioma lines for the expression of chemokine receptors belonging to the CXCR and CCR series revealed low to negligible levels of all receptors, with the exception of CXCR4 that was expressed by 13 of 16 lines. All six resected human glioma specimens showed similarly high CXCR4 expression. The CXCR4 on glioma lines is a signaling receptor in that its agonist, stromal cell-derived factor-1 (SDF-1; CXCL12), produced rapid phosphorylation of mitogen-activated protein kinases. Furthermore, SDF-1 induced the phosphorylation of Akt (protein kinase B), a kinase associated with survival, and prevented the apoptosis of glioma cells when serum was withdrawn from the culture medium. SDF-1 also mediated glioma chemotaxis, in accordance with this better known role of chemokines. We conclude that glioma cells express a predominant chemokine receptor, CXCR4, and that this functions to regulate survival in part through activating pathways such as Akt.     

通过优化表达元件及培养基组分提高地衣芽胞杆菌中碱性丝氨酸蛋白酶产量

【背景】碱性丝氨酸蛋白酶(Subtilisin)是一种具有广泛用途的工业酶制剂。【目的】旨在通过优化启动子、信号肽及培养基组分来提高地衣芽胞杆菌中碱性丝氨酸蛋白酶产量。【方法】以地衣芽胞杆菌BL10为出发菌株,构建了含有4种不同类型启动子(PbacA、P43、PaprE和PsrfA)及4种不同类型信号肽(SPVpr、SPSacB、SPSacC和SPAprE)的碱性丝氨酸蛋白酶表达菌株,并在获得高产菌株的基础上进行培养基优化。【结果】4种启动子的表达水平为PbacAPaprEP43PsrfA,4种信号肽的分泌效率为SPAprESPSacCSPSacBSPVpr。其中,菌株BL10/pPbacA-aprE产生最高的碱性丝氨酸蛋白酶酶活(275.21 U/mL),相比于出发菌株BL10/pHY-aprE (167.98 U/mL)提高了64%。随后,通过对发酵培养基成分进行优化并结合正交优化,获得了一种高产碱性丝氨酸蛋白酶的培养基(g/L):玉米淀粉40.0,豆粕50.0,(NH4)2SO4 4.0,K2HPO4 3.0,CaCO3 1.0。最后,碱性丝氨酸蛋白酶酶活提高到747.37 U/mL,是初始酶活的4.45倍。【结论】为工业化高产碱性丝氨酸蛋白酶提供了一种有效策略。