Structure of plant photosystem I−light harvesting complex I supercomplex at 2.4 Å resolution

Photosystem I (PSI) is one of the two photosystems in photosynthesis, and performs a series of electron transfer reactions leading to the reduction of ferredoxin. In higher plants, PSI is surrounded by four light-harvesting complex I (LHCI) subunits, which harvest and transfer energy efficiently to the PSI core. The crystal structure of PSI-LHCI supercomplex has been analyzed up to 2.6 Å resolution, providing much information on the arrangement of proteins and cofactors in this complicated supercomplex. Here we have optimized crystallization conditions, and analyzed the crystal structure of PSI-LHCI at 2.4 Å resolution. Our structure showed some shift of the LHCI, especially the Lhca4 subunit, away from the PSI core, suggesting the indirect connection and inefficiency of energy transfer from this Lhca subunit to the PSI core. We identified five new lipids in the structure, most of them are located in the gap region between the Lhca subunits and the PSI core. These lipid molecules may play important roles in binding of the Lhca subunits to the core, as well as in the assembly of the supercomplex. The present results thus provide novel information for the elucidation of the mechanisms for the light-energy harvesting, transfer and assembly of this supercomplex.     

Protein kinases in plant responses to drought,salt, and cold stress

Protein kinases are major players in various signal transduction pathways. Understanding the molecular mechanisms behind plant responses to biotic and abiotic stresses has become critical for developing and breeding climate-resilient crops. In this review,we summarize recent progress on understanding plant drought, salt, and cold stress responses, with a focus on signal perception and transduction by different protein kinases, especially sucrose nonfermenting1(SNF1)-related protein kinases(Sn RKs),mitogen-activated protein kinase(MAPK) cascades,calcium-dependent protein kinases(CDPKs/CPKs),and receptor-like kinases(RLKs). We also discuss future challenges in these research fields.     

甘草叶片形态结构和光合作用对干旱胁迫的响应

叶片结构在植物防御生物和非生物胁迫方面起着重要的作用,可通过合成、储存和分泌次生代谢产物提高植物抗性。以甘草幼苗为试材,采用盆栽控水自然干旱法,探讨叶片光合作用、气孔微形态和腺体形态对干旱胁迫的响应。结果表明:①随着干旱胁迫程度的加剧,叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均呈先升高后降低的趋势;其中胞间CO2浓度(Ci)在重度干旱胁迫(severe stress,SS)时迅速增高。②随着干旱胁迫程度的加剧,叶片总气孔密度和气孔开张比呈先增大后减小的趋势;而气孔开张宽度呈逐渐减小的趋势。③随着干旱胁迫程度的加剧,叶片上表皮和下表皮腺体密度总数整体上呈增大的趋势,腺体颜色随着干旱胁迫程度的加剧逐渐加深,形状出现不规则褶皱和内陷。总之,甘草叶片表面的腺体特征参与抗旱逆境调节,从而避免干旱胁迫对甘草植株的伤害;在SS下,胁迫程度加速了气孔细胞的程序性死亡(PCD),甘草幼苗失去抗旱能力。     

微生境对耐旱石生毛尖紫萼藓水分保持与散失特性的影响

毛尖紫萼藓(Grimmia pilifera)是典型石生耐旱藓类,水分是其生存繁衍的关键影响因素。为探究微生境对毛尖紫萼藓水分生理的影响,在安徽省大龙山国家森林公园低山丘陵区选择3种典型微生境(竹林遮蔽S-1,向阳裸岩E,薜荔灌丛遮蔽S-2),对比研究毛尖紫萼藓个体大小、饱和含水量及脱水过程中的含水量指标在不同微生境间的差异性,综合判断微生境对苔藓水分胁迫耐受性的影响及其权衡特征。结果表明:3种微生境毛尖紫萼藓个体大小及饱和含水量差异显著,其中竹林遮蔽生境毛尖紫萼藓具有较小的个体但拥有较高的内、外含水量。向阳裸岩和薜荔灌丛遮蔽生境植株大小及外吸水量接近,但前者内含水量更高。两荫蔽生境苔藓外吸水量是内吸水量的7倍,显著高于向阳裸岩生境的5.8倍。脱水过程中相同时间点向阳裸岩生境苔藓各含水量指标均高于两遮蔽生境,且达到相同含水量的时间差也随脱水进程持续而逐渐增大,这为向阳裸岩生境苔藓的有效光合作用(即相对含水量不低于35%时)及脱水后期的生理和结构调整赢得更多时间。综合而言,向阳裸岩生境毛尖紫萼藓比荫蔽生境具有更强的脱水耐受性,但后者可以通过增加外部吸水量来弥补失水过快的缺陷,这可能是不同微生境毛尖紫萼藓对水分吸收和保持的权衡策略。     

肺结节病合并Alternaria alternata所致皮肤链格孢病1例

患者,女,61岁,确诊肺结节病、口服糖皮质激素7月,双手背及腕部红色斑块3个月。组织病理示表皮轻度棘层增厚,真皮浅、中层中性粒细胞、淋巴、组织细胞、浆细胞、多核巨细胞混合性浸润,可见散在双轮廓厚壁酵母样结构。六铵银染色见不规则肿胀菌丝及酵母样厚壁孢子。真菌培养见棕/灰褐色菌落,镜下见棕色分隔孢子。ITS区序列分析鉴定为Alternaria alternate。口服伊曲康唑胶囊200 mg/d,联合外用硝酸舍他康唑乳膏2次/d,连续用药4个月后皮损完全消退,随访半年,未见复发。     

玉屏风颗粒联合西咪替丁对过敏性紫癜患儿临床疗效及外周血免疫学指标的影响

目的:探讨玉屏风颗粒联合西咪替丁对过敏性紫癜患儿临床疗效及外周血免疫学指标的影响。方法:选取2017年1月至2019年12月我院68例过敏性紫癜患儿为研究对象,根据随机化原则将受试儿进行分组,其中对照组34例患儿仅接受西咪替丁治疗,研究组45例患儿在对照组的基础上口服玉屏风颗粒治疗,比较两组的治疗效果、治疗前后外周血免疫学指标水平变化及用药安全性。结果:研究组临床治疗总有效率显著高于对照组(P<0.05),治疗前两组各免疫学指标及各炎性因子水平比较无统计学差异(P>0.05),治疗后两组各免疫学指标及各炎性因子水平较治疗前均明显降低,且研究组显著低于对照组(P<0.05),两组治疗期间不良反应发生率无差异(P>0.05)。结论:玉屏风颗粒联合西咪替丁可有效改善患儿的临床症状及外周血免疫学指标,疗效安全显著,值得在过敏性紫癜患儿治疗中应用及推广。     

Targeted sequencing and integrative analysis of 3,195 Chinese patients with neurodevelopmental disorders prioritized 26 novel candidate genes

Neurodevelopmental disorders(NDDs) are a set of complex disorders characterized by diverse and cooccurring clinical symptoms. The genetic contribution in patients with NDDs remains largely unknown.Here, we sequence 519 NDD-related genes in 3,195 Chinese probands with neurodevelopmental phenotypes and identify 2,522 putative functional mutations consisting of 137 de novo mutations(DNMs) in 86 genes and 2,385 rare inherited mutations(RIMs) with 22 X-linked hemizygotes in 13 genes, 2 homozygous mutations in 2 genes and 23 compound heterozygous mutations in 10 genes. Furthermore, the DNMs of16,807 probands with NDDs are retrieved from public datasets and combine in an integrated analysis with the mutation data of our Chinese NDD probands by taking 3,582 in-house controls of Chinese origin as background. We prioritize 26 novel candidate genes. Notably, six of these genes d ITSN1, UBR3, CADM1,RYR3, FLNA, and PLXNA3 d preferably contribute to autism spectrum disorders(ASDs), as demonstrated by high co-expression and/or interaction with ASD genes confirmed via rescue experiments in a mouse model. Importantly, these genes are differentially expressed in the ASD cortex in a significant manner and involved in ASD-associated networks. Together, our study expands the genetic spectrum of Chinese NDDs,further facilitating both basic and translational research.     

Leptin gene-targeted editing in ob/ob mouse adipose tissue based on the CRISPR/Cas9 system

Gene therapy has become the most effective treatment for monogenic diseases. Congenital LEPTIN deficiency is a rare autosomal recessive monogenic obesity syndrome caused by mutations in the Leptin gene. Ob/ob mouse is a monogenic obesity model, which carries a homozygous point mutation of C to T in Exon 2 of the Leptin gene. Here, we attempted to edit the mutated Leptin gene in ob/ob mice preadipocytes and inguinal adipose tissues using CRISPR/Cas9 to correct the C to T mutation and restore the production of LEPTIN protein by adipocytes. The edited preadipocytes exhibit a correction of 5.5% of Leptin alleles and produce normal LEPTIN protein when differentiated into mature adipocytes. The ob/ob mice display correction of 1.67% of Leptin alleles, which is sufficient to restore the production and physiological functions of LEPTIN protein, such as suppressing appetite and alleviating insulin resistance. Our study suggests CRISPR/Cas9-mediated in situ genome editing as a feasible therapeutic strategy for human monogenic diseases, and paves the way for further research on efficient delivery system in potential future clinical application.     

牦牛miR-383的靶基因预测及生物信息学分析

MicroRNAs (miRNAs)是一类非编码的小分子单链RNA,通过与靶基因的mRNA结合,抑制mRNA的翻译,参与多种生物学过程.本实验室前期通过高通量测序发现90日龄牦牛胚胎的背最长肌中miR-383的表达量显著高于成年牦牛.为探究miR-383在牦牛骨骼肌发育中的分子功能和机制,本研究对miR-383的靶基因进行预测,并进行生物信息学分析.通过TargetScan、miRDB和miRanda 3个软件预测了miR-383的靶基因,然后合并miRTarbase数据库中已被证实的靶基因作为基因集,分别用DAVID和KOBAS3.0在线软件对基因集进行功能注释(GO分析)和Pathway信号通路富集分析.结果 表明,牦牛miR-383序列在各物种间高度保守,靶基因功能富集于CD8阳性T细胞增殖的调控、核糖核蛋白复合物定位和负调控T细胞分化等生物学过程.信号通路分析发现靶基因的信号通路显著富集于PI3K-Ak、AMPK、FoxO和Focal adhesion等与肌肉发育相关的信号通路中.该研究结果将为miR-383功能及调控机制的深入研究提供参考依据,也为解析牦牛肌肉发育的分子机制提供新的研究方向.