MoSep3 and MoExo70 are needed for MoCK2 ring assembly essential for appressorium function in the rice blast fungus,Magnaporthe oryzae

Polar growth during appressorium formation is vital for the penetration peg formation in the rice blast fungus, Magnaporthe oryzae. Previous research has shown that the Sln1-septin-exocyst complex, localized at the base of the appressorium in contact with the leaf surface, forms a ring structure that influences growth polarity and affects penetration peg formation, and is necessary for pathogenicity. Our previous research showed CK2 proteins assemble another ring structure positioned perpendicular to the Sln1-septin-exocyst complex. Our research showed that the CK2 ring needs to become correctly assembled for penetration peg function and subsequent plant infection. In the present study, we found that the ring structures of CK2 are absent in the appressorium of ΔMoSep3 septin deletion mutants lacking the septin ring of the Sln1-septin-exocyst complex. Sln1 affects the septin proteins that recruit the exocyst complex that localizes as another ring at the appressorium's bottom. Destruction of the exocyst complex by mutation also causes incorrect localization of the CK2 ring structure. In conclusion, CK2 probably takes part in reestablishing the appressorium' spolarity growth necessary for penetration peg formation. We can also conclude that the correct localization and assembly of one or more CK2 ring structures in the appressorium depend on the initial assembly of the Sln1-septin-exocyst complex two rings at the base of the appressorium.     

两种内固定方法治疗老年骨盆后环骨折的疗效对比及对血清应激因子和疼痛相关生化指标的影响

摘要 目的：对比3D导航下经皮骶髂关节螺钉内固定、后路微创重建钢板内固定两种内固定方法治疗老年骨盆后环骨折的疗效及对血清应激因子和疼痛相关生化指标的影响。方法：回顾性分析2016年7月~2020年9月期间我院收治的100例老年骨盆后环骨折患者的临床资料。根据手术方式的不同将患者分为A组（n=50,后路微创重建钢板内固定）和B组（n=50,3D导航下经皮骶髂关节螺钉内固定）。对比两组手术相关指标、疼痛情况、Majeed功能评分、血清应激因子和疼痛相关生化指标变化情况。结果：B组术后3 d、术后1个月、术后3个月、术后1年视觉疼痛模拟评分（VAS）评分低于A组（P<0.05）。B组术中出血量少于A组,住院时间、手术时间、手术切口长度短于A组,但X线暴露时间长于A组（P<0.05）。B组术后1年Majeed功能评分高于A组（P<0.05）。B组术后7 d促甲状腺激素（TSH）水平高于A组,皮质醇（Cor） 、肾上腺素（E）水平低于A组（P<0.05）。B组术后7 d 5-羟色胺（5-HT）、P物质（SP）、前列腺素E2（PGE2）水平低于A组（P<0.05）。A组、B组的并发症发生率组间对比无显著性差异（P>0.05）。结论：与后路微创重建钢板内固定治疗老年骨盆后环骨折患者相比,3D导航下经皮骶髂关节螺钉内固定具有创伤小、手术时间短、术中出血量少、疼痛减轻、应激反应轻等诸多优势,可促进患者术后恢复。     

鼎湖山地区马尾松年轮元素含量与酸雨的关系

分析了鼎湖山马尾松年轮中几种化学元素含量的历史变化,并探讨了区域酸雨的影响。结果表明,酸雨有可能导致马尾松年轮中N、K和Al的含量在近30a中的上升趋势,和Ca、Mg和Mn明显的下降趋势。马尾松幼年期年轮部分元素含量异常地偏高,可能是幼年期生理机制不完善、对元素的选择性吸收和排斥能力较低所致,因此,以马尾松幼苗为对象进行的模拟酸雨试验结果,在推广至成熟的马尾松林地时可能会出现较大的偏差。     

A Novel Healing Filament in Ciliate Regeneration

The interphase cells of the hypotrich ciliate Paraurostyla weissei possess a complex fibrillar system surrounding basal bodies in the compound ciliary assemblages, cirri and membranelles. During replacement of the ciliature at cell division, transient filaments precede and accompany the development of ciliary primordia and participate in the formation of the fission furrow. Both fibrillar systems are recognized by monoclonal antibody FXXXIX 12G9. We studied regeneration of cellular fragments after transection employing the mAb 12G9 and found a new cytoskeletal structure involved in healing of the excisional wound. The healing filament is formed at the wound edge, distally and in connection with the bases of cirri closest to the wound. It is visible 5 min after transection. Concomitant with development of new ciliary primordia, the healing filament shrinks and finally disappears together with other transient fibers formed in this process. Ultrastructural analysis of immunolabeled regenerating cells revealed that structures recognized by mAb 12G9 contain fine filaments whose packing and arrangement depends on accompanying cytoplasmic elements and the developmental status of a fragment. Assembly of the healing fiber does not depend on microtubules and microfilaments since it develops in cellular fragments exposed to cold, nocodazole, and Cytochalasin D. On Western blots of whole cell and cytoskeletal extracts of P. weissei the 12G9 antibody identified one protein band whose molecular weight corresponds to 60 kDa.     

A novel regulatory role of TRAPPC9 in L-plastin-mediated osteoclast actin ring formation

Trafficking protein particle complex 9 (TRAPPC9) is a major subunit of the TRAPPII complex. TRAPPC9 has been reported to bind nuclear factor κB kinase subunit β (IKKβ) and NF-kB-inducing kinase (NIK) where it plays a role in the canonical and noncanonical of nuclear factor-κB (NF-kB) signaling pathways, receptively. The role of TRAPPC9 in protein trafficking and cytoskeleton organization in osteoclast (OC) has not been studied yet. In this study, we examined the mRNA expression of TRAPPC9 during OC differentiation. Next, we examined the colocalization of TRAPPC9 with cathepsin-K, known to mediate OC resorption suggesting that TRAPPC9 mediates the trafficking pathway within OC. To identify TRAPPC9 protein partners important for OC-mediated cytoskeleton re-organization, we conducted immunoprecipitation of TRAPPC9 in mature OCs followed by mass spectrometry analysis. Our data showed that TRAPPC9 binds various protein partners. One protein with high recovery rate is L-plastin (LPL). LPL localizes at the podosomes and reported to play a crucial role in actin aggregation thereby actin ring formation and OC function. Although the role of LPL in OC-mediated bone resorption has not fully reported in detail. Here, first, we confirmed the binding of LPL to TRAPPC9 and, then, we investigated the potential regulatory role of TRAPPC9 in LPL-mediated OC cytoskeleton reorganization. We assessed the localization of TRAPPC9 and LPL in OC and found that TRAPPC9 is colocalized with LPL at the periphery of OC. Next, we determined the effect of TRAPPC9 overexpression on LPL recruitment to the actin ring using a viral system. Interestingly, our data showed that TRAPPC9 overexpression promotes the recruitment of LPL to the actin ring when compared with control cultures. In addition, we observed that TRAPPC9 overexpression reorganizes actin clusters/aggregates and regulates vinculin recruitment into the OC periphery to initiate podosome formation.     

Myosin-II reorganization during mitosis is controlled temporally by its dephosphorylation and spatially by Mid1 in fission yeast

Cytokinesis in many eukaryotes requires an actomyosin contractile ring. Here, we show that in fission yeast the myosin-II heavy chain Myo2 initially accumulates at the division site via its COOH-terminal 134 amino acids independently of F-actin. The COOH-terminal region can access to the division site at early G2, whereas intact Myo2 does so at early mitosis. Ser1444 in the Myo2 COOH-terminal region is a phosphorylation site that is dephosphorylated during early mitosis. Myo2 S1444A prematurely accumulates at the future division site and promotes formation of an F-actin ring even during interphase. The accumulation of Myo2 requires the anillin homologue Mid1 that functions in proper ring placement. Myo2 interacts with Mid1 in cell lysates, and this interaction is inhibited by an S1444D mutation in Myo2. Our results suggest that dephosphorylation of Myo2 liberates the COOH-terminal region from an intramolecular inhibition. Subsequently, dephosphorylated Myo2 is anchored by Mid1 at the medial cortex and promotes the ring assembly in cooperation with F-actin.     

A role for septin 2 in Drp1‐mediated mitochondrial fission

Mitochondria are essential eukaryotic organelles often forming intricate networks. The overall network morphology is determined by mitochondrial fusion and fission. Among the multiple mechanisms that appear to regulate mitochondrial fission, the ER and actin have recently been shown to play an important role by mediating mitochondrial constriction and promoting the action of a key fission factor, the dynamin‐like protein Drp1. Here, we report that the cytoskeletal component septin 2 is involved in Drp1‐dependent mitochondrial fission in mammalian cells. Septin 2 localizes to a subset of mitochondrial constrictions and directly binds Drp1, as shown by immunoprecipitation of the endogenous proteins and by pulldown assays with recombinant proteins. Depletion of septin 2 reduces Drp1 recruitment to mitochondria and results in hyperfused mitochondria and delayed FCCP‐induced fission. Strikingly, septin depletion also affects mitochondrial morphology in Caenorhabditis elegans, strongly suggesting that the role of septins in mitochondrial dynamics is evolutionarily conserved.     

A single beta subunit M2 domain residue controls the picrotoxin sensitivity of alphabeta heteromeric glycine receptor chloride channels

This study investigated the residues responsible for the reduced picrotoxin sensitivity of the alphabeta heteromeric glycine receptor relative to the alpha homomeric receptor. By analogy with structurally related receptors, the beta subunit M2 domain residues P278 and F282 were considered the most likely candidates for mediating this effect. These residues align with G254 and T258 of the alpha subunit. The T258A, T258C and T258F mutations dramatically reduced the picrotoxin sensitivity of the alpha homomeric receptor. Furthermore, the converse F282T mutation in the beta subunit increased the picrotoxin sensitivity of the alphabeta heteromeric receptor. The P278G mutation in the beta subunit did not affect the picrotoxin sensitivity of the alphabeta heteromer. Thus, a ring of five threonines at the M2 domain depth corresponding to alpha subunit T258 is specifically required for picrotoxin sensitivity. Mutations to alpha subunit T258 also profoundly influenced the apparent glycine affinity. A substituted cysteine accessibility analysis revealed that the T258C sidechain increases its pore exposure in the channel open state. This provides further evidence for an allosteric mechanism of picrotoxin inhibition, but renders it unlikely that picrotoxin (as an allosterically acting 'competitive' antagonist) binds to this residue.     

不同海拔温度和降水对新疆阿尔泰山西伯利亚落叶松径向生长的影响

为定量并分离关键气候因子对新疆阿尔泰山不同海拔树木径向生长的影响,通过对高、中和低海拔的西伯利亚落叶松(Larixsibirica)树轮宽度标准年表与气候因子分别进行相关、多元线性回归等统计分析,并进一步计算了线性模型中不同气候因素的绝对和相对贡献率。结果表明,高海拔地区,当年6月温度和上年7月降水分别与径向生长呈显著正相关和负相关,两者共同解释西伯利亚落叶松径向生长变异的33.1%,相对贡献率分别为66.2%和33.8%;中海拔地区,当年6月温度和上年6月降水分别与径向生长呈显著正相关和负相关,两者共同解释径向生长变异的26.8%,相对贡献率分别为40.1%和59.9%;低海拔地区,上年6月温度和7月降水分别与径向生长呈显著负相关和正相关,两者共同解释径向生长变异的29.4%,相对贡献率分别为31.9%和68.1%。这表明限制树木径向生长的主要影响因子随海拔的不同而异,在高海拔地区,温度是主要限制因子;而在低海拔地区,降雨是主要限制因子。