Structure of desheptapeptide (B24-B30) insulin in a new crystal form

The structure of desheptapeptide (B24-B30) insulin (DHPI) in a new crystal form (form B) has been determined and refined to 0.2 nm resolution. The crystals were obtained under the same crystallization condition as previously reported crystal form (form A). The overall structures of the two crystal forms are similar but obvious differences can be observed in crystal packing and local conformation. The crystal structures of the two forms show that the two independent molecules in an asymmetric unit from a DHPI dimer, and the dimer formation buries more than 18.20 and 16.95 nm~2 of solvent accessible surfaces for form A and form B DHPI, respectively, the largest among insulin and insulin analogs ever reported. Close examination at crystal packing shows that the dimer-forming surface of DHPI, namely Surface Ⅱ, is normally present in the association of insulin and insulin analogs in their crystal structures. The results demonstrate that Surface Ⅱ is crucially important for the formation of two crystal form     

湖南省木本植物上的拟茎点霉新种

报道了采自湖南省木本植物上的10个拟茎点霉Phomopsis新种,即喜树拟茎点霉Ph. camptothecae、腊梅拟茎点霉Ph.chimonanthi、杜仲生拟茎点霉Ph.eucommiicola、紫薇拟茎点霉Ph.lagerstroemiae、红继木拟茎点霉Ph.loropetali、厚朴拟茎点霉Ph.magnolina、海桐拟茎点霉Ph.pittospori、竹柏拟茎点霉Phomopsis podocarpi、石榴拟茎点霉Ph.punicicola和酸枣拟茎点霉Ph.ziziphicola。对新种与其近似种在形态及ITS序列上的差异进行了讨论。文中附有新种的拉丁文、英文描述及显微结构图。模式标本保存于华南农业大学真菌标本室(SCHM)。     

Integrin Activation and Viral Infection

Integrins are members of a ubiquitous membrane receptor family which includes 18 different α subunits and 8 β subunits forming more than 20 α/β heterodimers. Integrins play key functions in vascular endothelial cell and tumour cell adhesion, lymphocyte trafficking, tumor growth and viral infection. Current understanding of the molecular basis of integrins as viral receptors has been achieved through many decades of study into the biology of transmembrane glycoproteins and their interactions with several viruses. This review provides a summary of the current knowledge on the molecular bases of interactions between viruses and integrins, which are of potential practical significance. Inhibition of virus-integrin interactions at the points of virus attachment or entry will provide a novel approach for the therapeutic treatment of viral diseases.     

黄土高原典型草原群落结构和土壤水分对划破的响应

划破是草原改良的基础措施之一，划破强度是划破措施的关键环节，划破对草原健康持续管理有重要意义。目前的研究主要集中在划破对植物群落结构和生产力的影响上，然而草原植物群落与土壤水分对划破强度的响应尚不清楚。在黄土高原典型草原开展不同程度的草地划破试验，探究不同划破强度（27.4%、46.3%和61.9%）对草地植物群落物种多样性、生物量和土壤水分的影响。结果表明：3个划破强度下划破带物种丰富度显著低于未划破带1-3种/m²，划破带和未划破带群落相似性分别低于整区23.85%-119.23%和44.43%-84.55%。地上生物量随物种丰富度的增加而增大，且地上生物量与Simpson指数和Shannon Weiner指数显著负相关。3个划破强度下未划破带地下生物量和总生物量分别高于划破带88.2%-134.6%、52.4%-67.8%、2.5%-16.6%和103.9%-152.9%、59.3%-75.8%、9.1%-22.6%。植物群落物种丰富度和地上生物量随划破强度的增加呈"驼峰"型曲线变化，当划破强度分别为43.7%-55.3%和43.8%-45.7%时，植物群落物种丰富度和生物量均最高。本试验阐明了划破对典型草原植物群落特征和土壤水分的作用机制，研究结果为采用划破措施实现草地培育和草原修复提供了科学依据，对保护草地生物多样性和提高生产力具有重要意义。     

Molecular replacement studies on crystal structure of allophycocyanin from red algae Porphyra yezoensis

Using the crystal structure of allophycocyanin from cyanobacterium Spirulina platensis (APC-SP) as a search model,the crystal structure of allophycocyanin from red algae Porphyra yezoensis (APC-PY) has been studied by molecular replacement methods.The APC-PY crystals (Form 3) belong to the space group of R32,cell dimensions a=b= 10.53 nm,c=18.94 nm,α= β= 90°,γ=120°;there is one αβ monomer in each crystallographic asymmetric unit in the cell.The translation function search gave a unique peak with a correlation coefficient (Cc) of 67.0% and an R-factor of 36.1% for reflection data from 1.0 to 0.4 nm.Using the results by molecular replacement,the initial model of APC-PY was built,and the coincidence of the chromophore in APC-PY initial model with its 2Fo-Fc OMIT map further confirms the results by molecular replacement.     

小柴旦盐湖脱硫棒状菌属的环境适应性机制分析

【目的】青藏高原小柴旦盐湖富含硫酸盐卤水,宏基因组学分析揭示该生境蕴藏着丰富的具有耐盐、固碳和脱硫功能的微生物。本研究拟通过生物信息学分析揭示潜在的固碳脱硫微生物脱硫棒状菌(Desulfotignum)的代谢多样性和环境适应性机制。【方法】利用宏基因组分箱分析和公共数据库下载获得小柴旦盐湖脱硫棒状菌属的基因组,通过文献跟踪和16S rRNA基因数据库检索揭示脱硫棒状菌的全球生境分布,基于基因组分类数据库(genome taxonomy database, GTDB)中120个细菌标记蛋白的系统发育树对脱硫棒状菌属的亚群进行分类,通过重构脱硫棒状菌属不同亚群的生理代谢潜能以及基因组比较分析来解析其环境适应机制和代谢多样性。【结果】脱硫棒状菌属全球分布广泛且主要栖息在高盐生境。小柴旦盐湖沉积物中共得到了9个脱硫棒状菌基因组,结合公共数据库中2个基因组,根据基因组系统发育分析、平均核苷酸一致性(average nucleotide identity,ANI)和平均氨基酸一致性(average amino acid identity, AAI)分析将这11个脱硫棒状菌基因组分为了2个亚群(G1...     

乌兰布和沙漠天然梭梭种群动态及空间分布

为进一步明晰乌兰布和沙漠天然梭梭(Haloxylon ammodendron)种群动态和空间分布特征,该研究以乌兰布和沙漠天然梭梭林为研究对象,采用静态生命表、存活曲线、生存分析和空间分布格局指数等方法分析种群动态与内在生活史特征和外在干扰之间的互动关系,探讨梭梭种群波动特征及其存续机制,以揭示天然梭梭种群动态及空间分布特征,为梭梭种群的合理保护与种群恢复提供依据。结果表明:(1)乌兰布和沙漠天然梭梭种群龄级结构呈倒“J”形,为增长型,但相邻龄级个体数量波动性较大;种群年龄结构数量变化动态指数V_(pi)=17.43,受随机干扰时种群年龄结构动态指数V_(pi)′=1.02,种群年龄结构对随机干扰的敏感性指数P_(max)=5.88,说明种群对外界干扰较为敏感。(2)研究区天然梭梭种群的存活曲线趋于Deevey-Ⅱ型,各年龄级种群有相近的死亡率;生存函数、累积死亡率、死亡密度在第Ⅰ~Ⅹ龄级(基径<10 cm)变化较大,且在第Ⅰ~Ⅸ龄级危险率较高;生存函数、累计死亡率、死亡密度在第Ⅺ~ⅩⅧ龄级(基径≥10 cm)趋于稳定,危险率在第Ⅹ龄级后逐渐增加,种群动态呈现出低龄级间个体数量波动大,高龄级衰退的特征。(3)研究区天然梭梭种群密度在328.57~942.86株/km^(2)之间,平均为706.34株/km^(2),种群空间分布大多呈聚集分布。研究表明,乌兰布和沙漠在现阶段环境气候条件下,适宜梭梭种群的生长,而且在不受人为干扰的情况下,梭梭种群能够稳定存续,可以抵抗一定的气候风险。建议减轻人为干扰对低龄级种群数量的影响,在局部梭梭林衰退严重区可参考天然梭梭种群密度与空间分布型建植人工梭梭林。     

番茄(Solanum lycopersicum)类胡萝卜素降解关键基因筛选

类胡萝卜素衍生挥发物对提升番茄风味至关重要。为筛选调控类胡萝卜素衍生挥发物合成的关键基因,以90个番茄自交系中香气寡淡的TI4001和香气浓郁的CI1005为材料,分析了番茄类胡萝卜素裂解双加氧酶(SlCCDs)基因在不同组织及不同发育期果实中的表达量,果实不同成熟期类胡萝卜素及其衍生挥发物的含量。发现在7个SlCCDs基因中,SlCCD1A和SlCCD1B基因在番茄果实中表达量最高,且随着果实发育成熟表达量显著升高。果实中类胡萝卜素及其衍生挥发物含量也显著升高。SlCCD1A和SlCCD1B基因表达量与类胡萝卜素及其衍生挥发物含量之间极显著正相关。推测SlCCD1A和SlCCD1B基因是裂解类胡萝卜素合成挥发物的关键基因。     

2001—2019年黄土高原植被覆盖度时空演化特征及地理因子解析

探究黄土高原植被覆盖度变化及其与地理因子之间的关系有助于区域植被恢复政策的优化以及人地关系的协调发展。因此,以MOD13 A1数据作为数据基础,采用趋势分析、标准差和重心迁移模型,研究2001—2019年黄土高原植被覆盖度FVC(Fractional Vegetation Cover)时空演化特征,并结合地理探测器和相关分析对影响FVC的地理因子进行解析。结果表明：(1)2001—2019年黄土高原植被覆盖度恢复状况较好,FVC平均增速为0.0095/a,呈东南高西北低分布,极显著、显著增加的区域面积占比为84.37%,研究区各年FVC重心位于陕北一带,19年向北推进55.1km;(2)各地理因子对FVC的解释力存在显著差异,降水、土壤类型、气温、土地利用类型和坡度是FVC空间分布的主要驱动因子,且各因子之间交互作用的解释力高于单因子;(3)FVC与气温、降水相关系数均以正相关为主;FVC均值与变化趋势存在地形、土壤、人口密度、土地利用分异特征;土地利用转移可体现人类活动特征,其退耕还林还草、未利用地绿化等积极效应促使区域植被得到显著改善,城市扩张等消极效应则抑制植被增长。     

中国地下真菌新种和新记录Ⅳ

本文报道了中国地下真菌2新种和1新记录,它们分别是:南京无索腹菌Martelliananjingensis Liu et K.Tao sp.nov.,中国乳腹菌Zelleromyces sinensis Liu,K.Tao etChang sp.nov.和罗杰斯奥腹菌Octavianina rogersii Singer et Smith。