Somatic Embryogenesis in Cell Suspension Culture of Saposhnikovia divaricata

Calli of Saposhnikovia divaricata (Turcz.) Schischk. were induced from the roots of test tube seedlings cultured on MS medium containing 0.5 mg/L 2,4-D. Cell suspension was established by shaking the caul in liquid medium of the same components supplemented with 10% coconut milk. After the formation of embryogenic clusters, 2,4-D was omitted promoting the transformation of the embryogenic clusters to somatic embryos. Micro and submicroscopic: structural changes during the single cell to globular embryonic stage were observed. It was noticed that cortical endoplasmic reticulum appeared in the cells at the stage of embryogenic clump formation but was absent in other stages. Perhaps this was related to the metabolic specification leading to embryo formation. Spherosomes were observed of embryogenesis but remarkably increased in number at proglobular embryo stage. Meanwhile, the central electric dense matrix became progressively smaller and paler, while the outer part became enlarged and more transparent. This implied that the spherosomes took part in the storage of proteins or lipidproteins in the early stages of embryogenesis and transformation to lipid dror)s when the proteins were exhausted in the development of embryo, vacuolar protein bodies could be risualized in many cells in the proglobular embryo stage. This together with the existance and changes of spherosomes was similar to that observed in Peucedanum terebmthaceum. Further studies are meritted to approach, whether these are general phenomena in Umbelliferae. This work also revealed that the aggregation of single cells in suspension culture stimulated the initiation of embryogenesis.     

死皮对橡胶树树皮线粒体超微结构及活性氧代谢的影响

为了解析橡胶树（Hevea brasiliensis）死皮的发生机制,有效进行死皮防治,以健康、轻度死皮、重度死皮橡胶树树皮为材料,研究死皮发生过程中树皮线粒体超微结构变化规律及活性氧（ROS）相关基因的表达模式变化。结果表明：死皮树线粒体超微结构发生不规则形变,膜内基质溶解,嵴消失,内腔空泡化等,且严重程度与死皮严重程度成正比。荧光定量PCR结果表明,过氧化物酶基因HbPOD2和HbPOD3在死皮树中的表达量高于健康树,可作为监测割胶强度、刺激强度和死皮发生的“标志”基因。植物细胞重要ROS清除酶过氧化氢酶基因HbCAT在死皮树中也下调表达,预示ROS产生与清除之间的平衡是影响橡胶树死皮发生的关键因素。橡胶树中重要抗氧化代谢物基因表达结果表明,HbGST1、HbGST2和HbPPO在死皮树中的表达量均高于健康树,可能与死皮发生过程胶乳原位凝固相关。本研究通过揭示死皮发生过程树皮超微结构和ROS相关基因表达模式变化,为阐明橡胶树死皮发生机制提供新观点,同时为进一步开发监测割胶强度、刺激强度和死皮发生的基因“标志”提供理论基础。     

Integrated Machine Learning and Bioinformatic Analyses Constructed a Novel Stemness-Related Classifier to Predict Prognosis and Immunotherapy Responses for Hepatocellular Carcinoma Patients

Immunotherapy has made great progress in hepatocellular carcinoma (HCC), yet there is still a lack of biomarkers for predicting response to it. Cancer stem cells (CSCs) are the primary cause of the tumorigenesis, metastasis, and multi-drug resistance of HCC. This study aimed to propose a novel CSCs-related cluster of HCC to predict patients'' response to immunotherapy. Based on RNA-seq datasets from The Cancer Genome Atlas (TCGA) and Progenitor Cell Biology Consortium (PCBC), one-class logistic regression (OCLR) algorithm was applied to compute the stemness index (mRNAsi) of HCC patients. Unsupervised consensus clustering was performed to categorize HCC patients into two stemness subtypes which further proved to be a predictor of tumor immune microenvironment (TIME) status, immunogenomic expressions and sensitivity to neoadjuvant therapies. Finally, four machine learning algorithms (LASSO, RF, SVM-RFE and XGboost) were applied to distinguish different stemness subtypes. Thus, a five-hub-gene based classifier was constructed in TCGA and ICGC HCC datasets to predict patients'' stemness subtype in a more convenient and applicable way, and this novel stemness-based classification system could facilitate the prognostic prediction and guide clinical strategies of immunotherapy and targeted therapy in HCC.     

DNA条形码在热带龙脑香科树种鉴定中的应用

龙脑香科植物是东南亚地区重要的热带木材来源树种, 对其开展DNA条形码评估在林业监管及森林资源保护等方面具有非常重要的实际应用价值。通过对龙脑香科植物样品进行rbcL、matK、trnL-trnF和ITS2四个片段的扩增和测序, 结合GenBank下载的数据, 共获得龙脑香科树种14属244种共计899条序列。通过比较4个片段的通用性、序列特征、种内和种间的遗传变异, 基于Best Match (BM)、Best Close Match (BCM)、相似性搜索算法(BLAST)和邻接树(NJ) 4种方法评估DNA条形码对于龙脑香科树种的鉴定能力。结果表明, ITS2在龙脑香科树种中鉴定效率最高, 通过优化的扩增体系能够从该科植物叶片中获得较高质量的ITS2片段; 叶绿体matK片段扩增和测序效率为100%, 且种内及种间遗传变异明显, 鉴定成功率高于其它叶绿体片段, 并据此提出ITS2和matK适合作为龙脑香科树种的DNA条形码。     

水稻土中铁氧化物对产甲烷古菌群落结构的影响

产甲烷菌广泛分布在淹水水稻土等各种厌氧环境中,在全球气候变化、碳循环和能源等领域都发挥着重要的作用。研究发现,厌氧条件下,水稻土中铁氧化物的生物还原会抑制产甲烷菌的甲烷合成作用。然而,目前关于铁氧化物对产甲烷菌群落结构的影响报道较少。通过泥浆厌氧培养实验,向采集的水稻土中添加甲酸盐作为甲烷合成的底物(Control,CK处理),并设置添加水铁矿作为体系中唯一电子受体的处理组(Ferrihydrite,Fh处理)。培养结束后,与CK相比,添加水铁矿显著降低了古菌在总微生物群落中的占比,但对古菌群落的物种多样性和均一度没有显著影响;且两组处理中优势种均为操作分类单元(Operational taxonomic unit,OTU)2056和OTU 911(76%—80%)。这说明碳源相同时,产甲烷菌的群落结构不受铁氧化物的影响。本研究为探索土壤中微生物铁还原与碳循环耦合的分子机制奠定基础。     

Genetic analysis of leaffolder resistance in rice

A double haploid(DH)population,which consists of 120 lines derived from anther culture of a typical indica and japonica hybrid 'CJ06'/'TN1',was used to investigate the genetic basis for rice leaffolder resistance.Using a constructed molecular linkage map,five QTLs for rolled leaves were detected on chromosomes 1,2,3,4,and 8.The positive alleles from CJ06 on chromosomes 3,4,and 8 in-creased the resistance to rice leaffolder,and the alleles from TN1 on chromosomes 1 and 2 also enhanced resistance to leaffolde...