Genome-Wide Identification and Expression Patterns of the SWEET Gene Family in Bletilla striata and its Responses to Low Temperature and Oxidative Stress

SWEETs (sugars will eventually be exported transporters), a well-known class of sugar transporters, are involved in plant growth and development, sugar transport, biotic and abiotic stresses, etc. However, to date, there have been few investigations of SWEETs in Orchidaceae. In this study, 23 SWEET genes were identified in Bletilla striata for the first time, with an MtN3/saliva conserved domain, and were divided into four subgroups by phylogenetic tree. The same subfamily members had similar gene structures and motifs. Multiple cis-elements related to sugar and environmental stresses were found in the promoter region. Further, 21 genes were localized on 11 chromosomes and 2 paralogous pairs were found via intraspecific collinearity analysis. Expression profiling results showed that BsSWEETs were tissue-specific. It also revealed that BsSWEET10 and BsSWEET18 were responsive to low temperature and oxidative stresses. In addition, subcellular localization study indicated that BsSWEET15 and BsSWEET16 were localized in the cell membrane. This study provided important clues for the in-depth elucidation of the sugar transport mechanism of BsSWEET genes and their functional roles in response to abiotic stresses.     

SHMT2 Induces Stemness and Progression of Head and Neck Cancer

Various enzymes in the one-carbon metabolic pathway are closely related to the development of tumors, and they can all be potential targets for cancer therapy. Serine hydroxymethyltransferase2 (SHMT2), a key metabolic enzyme, is very important for the proliferation and growth of cancer cells. However, the function and mechanism of SHMT2 in head and neck cancer (HNC) are not clear. An analysis of The Cancer Genome Atlas (TCGA) data showed that the expression of SHMT2 was higher in tumor tissue than in normal tissue, and its expression was significantly associated with male sex, aggressive histological grade, lymph node metastasis, distant metastasis, advanced TNM stage, and lymphovascular invasion in HNC. SHMT2 knockdown in FADU and SNU1041 cell lines significantly inhibited cell proliferation, colony formation, migration, and invasion. Additionally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses using TCGA data revealed that SHMT2 was closely related to cancer stem cell regulation and maintenance. Furthermore, we found that silencing SHMT2 inhibited the expression of stemness markers and tumor spheroid formation compared with a control group. On the contrary, stemness markers were significantly increased after SHMT2 overexpression in HEP-2 cells. Interestingly, we found that knocking down SHMT2 reduced the expression of genes related to the Notch and Wnt pathways. Finally, silencing SHMT2 significantly reduced tumor growth and decreased stemness markers in a xenograft model. Taken together, our study suggests that targeting SHMT2 may play an important role in inhibiting HNC progression.     

Genome Editing of Golden SNP-Carrying Lycopene Epsilon-Cyclase (LcyE) Gene Using the CRSPR-Cas9/HDR and Geminiviral Replicon System in Rice

Lycopene epsilon-cyclase (LcyE) is a key enzyme in the carotenoid biosynthetic pathway of higher plants. Using the CRSPR/Cas9 and the geminiviral replicon, we optimized a method for targeted mutagenesis and golden SNP replacement of the LcyE gene in rice. We have exploited the geminiviral replicon amplification as a means to provide a large amount of donor template for the repair of a CRISPR-Cas-induced DNA double-strand break (DSB) in the target gene via homology-directed repair (HDR). Mutagenesis experiments performed on the Donggin variety achieved precise modification of the LcyE loci with an efficiency of up to 90%. In HDR experiments, our target was the LcyE allele (LcyE-H523L) derived from anther culture containing a golden SNP replacement. The phenotype of the homologous recombination (HR) mutant obtained through the geminiviral replicon-based template delivery system was tangerine color, and the frequency was 1.32% of the transformed calli. In addition, the total carotenoid content of the LcyEsg2-HDR1 and LcyEsg2-HDR2 lines was 6.8–9.6 times higher than that of the wild-type (WT) calli, respectively. The reactive oxygen species content was lower in the LcyEsg2-HDR1 and LcyEsg2-HDR2 lines. These results indicate that efficient HDR can be achieved in the golden SNP replacement using a single and modular configuration applicable to different rice targets and other crops. This work demonstrates the potential to replace all genes with elite alleles within one generation and greatly expands our ability to improve agriculturally important traits.     

Hypoxia Promotes Angiogenic Effect in Extracranial Arteriovenous Malformation Endothelial Cells

Arteriovenous malformation (AVM) is characterized by high-flow blood vessels connecting arteries and veins without capillaries. This disease shows increased angiogenesis and a pathophysiological hypoxic environment in proximal tissues. Here, we analyzed the effects of hypoxia on angiogenesis in the endothelial cells (ECs) of AVM and normal tissues. ECs from human normal and AVM tissues were evaluated using immunocytochemistry with CD31. In vitro tube formation under hypoxia was tested in both ECs using Matrigel. The relative expression of angiogenesis-related genes was measured using real-time PCR. Under normoxia, CD31 was significantly higher in AVM ECs (79.23 ± 0.65%) than in normal ECs (74.15 ± 0.70%). Similar results were observed under hypoxia in AVM ECs (63.85 ± 1.84%) and normal ECs (60.52 ± 0.51%). In the tube formation test under normoxic and hypoxic conditions, the junction count and total vessel length were significantly greater in AVM ECs than normal ECs. Under both normoxia and hypoxia, the angiogenesis-related gene FSTL1 showed a significantly higher expression in AVM ECs than in normal ECs. Under hypoxia, CSPG4 expression was significantly lower in AVM ECs than in normal ECs. Accordingly, the angiogenic effect was increased in AVM ECs compared with that in normal ECs. These results provide a basic knowledge for an AVM treatment strategy.     

聚丙烯交联技术发展现状

交联聚丙烯具有优异的机械性能和热性能。本文就当前聚丙烯的几种交联技术进行了总结与分类,并介绍了各自的反应机理。着重讨论了最常见的几种PP的交联工艺及其特性,包括有机过氧化物交联、硅烷接枝交联、辐射交联等。     

Quantum verification of NP problems with single photons and linear optics

Quantum computing is seeking to realize hardware-optimized algorithms for application-related computational tasks. NP (nondeterministic-polynomial-time) is a co...     

PASSIM7000卷烟机回丝量控制改进

针对PASSIM7000卷烟机供丝系统回丝量控制系统数据采集及处理方式存在的问题,设计出一种新的数据采集及处理方式,采用改变测量位置,及时获取供丝量变化信息;使用激光位移传感器进行精确数值测量;采用最小二乘法对测量数值进行曲线拟合,再根据拟合曲线对回丝量多少进行预测并及时调节等方法,解决了原控制方式造成的反馈滞后,响应不及时等缺陷。改进后的PASSIM7000型卷烟机供丝系统,提高了供丝的均匀性,降低了烟支的空头率。     

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Ohne Zusammenfassung VDI     

核电厂隔震结构的振动台试验研究

随着我国核电产业飞速发展,核电站厂址的选择将不可避免地遇到非基岩场地。针对地震动斜入射下非基岩场地中核电结构抗震问题,建立了包括CAP1400核岛结构和岩土场地的土-结构系统三维有限元模型,基于黏弹性人工边界和斜入射地震动输入方法,研究了P波斜入射角度和非基岩分层场地对核岛结构地震响应的影响规律。研究表明：非基岩场地将增大核岛结构加速度响应和楼层反应谱,多数条件下也将增大楼层相对位移;P波入射角度增大,核岛结构竖向响应减小、水平响应增大,楼层反应谱的频谱特性发生改变。     

挤压性破碎软岩隧道大变形特征及机制研究

为了实现对埋深的模拟,考虑振动台的载重量,设计并制作了一套质量较轻的柔性伺服气压加载系统.分别开展了考虑和不考虑松动圈的振动台模型试验,同时建立了相应工况的隧道动力计算数值模型,将试验结果与数值计算结果进行了对比.模型试验数据与数值模拟结果规律较为一致,且反映了松动圈的动力响应影响,表明采用柔性加载来模拟埋深产生的地应力的方法是可行的.结果表明：在一定埋深条件下,隧道结构的自身振动特性表现不明显;松动圈的存在增大了隧道结构和周围岩体的加速度响应,从而使结构破坏程度更为严重;无论有无松动圈,结构整体的动力响应规律相似.松动圈对隧道结构地震动响应的不利影响可以归结为松动圈与围岩交界面发生地震波的折射和反射以及松动圈相比于围岩较软弱,地震时更容易发生局部变形这2个因素.