三种壁虎染色体核仁组织者的银染色观察与蹼壁虎的核型

本文以骨髓细胞为材料, 采用常规制片法和一步银染色技术,首次报道了无蹼壁虎、铅山壁虎和多疣壁虑的NORs,并用α-巯基乙醇短期培养无蹼壁虎的骨髓细胞,分析其核型。结果表明,3种壁虎都仅显示一对NORs,也未见有融合现象。其中无蹼壁虎的NORs位于第18对染色体的次缢痕区,而铅山壁虎和多疣壁虎分别位于第19对和第14对上。另外,我们从C带分析中发现,铅山壁虎和多疣壁虎的NORs位点均为结构异染色质区。经α-巯基乙醇培养的无蹼壁虎的染色体明显“拉长”。具次缢痕的染色体可从以往报道的第 19 对调整为第18对,其次缢痕区也比直接制作的标本大而清晰。     

平衡施肥及雨强对紫色土养分流失的影响

利用人工降雨装置模拟3种不同强度的降雨,采用模拟径流小区,研究了四川紫色丘陵区玉米净作条件下雨强及平衡施肥对土壤养分损失量及载体的影响.结果表明:雨强是影响地表径流量、径流总量及土壤侵蚀量的最主要因素.在小雨强条件下,无地表径流及土壤侵蚀发生;随着雨强的增大,地表径流量、径流总量及土壤侵蚀量都急剧增加.磷素和钾素流失总量也随雨强的增加而增加,而雨强对氮素流失的影响不大.在3种雨强条件下,3种施肥处理的氮素流失总量表现为:高氮施肥>农户习惯施肥>平衡施肥,平衡施肥能减少氮素流失,而高氮施肥增加氮素的流失.农户习惯施肥处理的磷流失总量和钾流失总量均高于平衡施肥和高氮施肥两种施钾处理,在紫色土坡耕地增施钾肥能减少磷、钾养分的流失.     

慈姑45S rDNA和端粒序列检测及核型分析

以45S r DNA和拟南芥型端粒序列为探针对慈姑(Sagittaria trifolia L.)有丝分裂中期染色体进行单色和双色荧光原位杂交分析,并用银染方法检测慈姑45S r DNA位点的表达,最后结合染色体测量数据和45S r DNA杂交信号建立慈姑的核型。结果显示,慈姑的单倍基因组总长度为76.9±1.38μm,最长染色体为11.55±0.10μm,最短染色体为4.54±0.27μm;慈姑的核型公式为:2n=22=2m+2sm+14st+4t,核型不对称性参数CI、A1、A2、As K(%)、AI分别为19.86±11.06、0.72、0.27、78.82、15.29,核型属于Stebbins类型中的3B型。慈姑具有3对45S r DNA位点,分别位于第8、9、10号染色体的短臂末端。拟南芥型端粒序列的杂交信号出现在慈姑每一条染色体的长、短臂末端。银染检测到6个Ag-NOR和6个核仁,表明3对45S r DNA位点在间期核都有表达。本研究结果为药食兼用植物慈姑提供了分子细胞遗传学基础资料。     

Lipid droplets maintain lipid homeostasis during anaphase for efficient cell separation in budding yeast

The neutral lipids steryl ester and triacylglycerol (TAG) are stored in the membrane-bound organelle lipid droplet (LD) in essentially all eukaryotic cells. It is unclear what physiological conditions require the mobilization or storage of these lipids. Here, we study the budding yeast mutant are1Δ are2Δ dga1Δ lro1Δ, which cannot synthesize the neutral lipids and therefore lacks LDs. This quadruple mutant is delayed at cell separation upon release from mitotic arrest. The cells have abnormal septa, unstable septin assembly during cytokinesis, and prolonged exocytosis at the division site at the end of cytokinesis. Lipidomic analysis shows a marked increase of diacylglycerol (DAG) and phosphatidic acid, the precursors for TAG, in the mutant during mitotic exit. The cytokinesis and separation defects are rescued by adding phospholipid precursors or inhibiting fatty acid synthesis, which both reduce DAG levels. Our results suggest that converting excess lipids to neutral lipids for storage during mitotic exit is important for proper execution of cytokinesis and efficient cell separation.     

Visualization and Characterization of High-Order Chromatin Fibers under Light Microscope during Interphase and Mitotic Stages in Plants

Using genomic in situ hybridization with genomic DNA, high-order chromatin fibers were successfully exhibited under a light microscope through the cell cycle in barley, rice, maize and field bean. From the interphase to prophase and metaphase of mitosis, the fibers were basically similar. Each was estimated to be around 200 nm in diameter, but the strength of signals was not the same along the fiber length. Through the cell cycle a series of dynamic distribution changes occurred in the fibers. In the interphase, they were unraveled. At the early prophase they were arranged with parallel and mirror symmetry. During late-prophase and metaphase, the fibers were bundled and became different visible chromosomes. The parallel coiling and mirror symmetry structures were visible clearly until the metaphase. In anaphase they disappeared. During telophase, in peripheral regions of congregated chromosome group, borderlines of the chromosomes disappeared and the fibers were unraveled. This demonstrated that mitotic chromosomes are assembled and organized by parallel and adjacent coiling of the fibers and the fibers should be the highest order structure for DNA coiling.     

植物rRNA基因组织模式的荧光原位杂交比较分析

采用荧光原位杂交技术,对分属5个科的10种植物的分生细胞的18S-25S rRNA基因(45S rDNA)的组织模式进行了比较分析.45S rDNA探针在所有供试植物的间期核都产生了两种杂交信号:荧光强、位于核仁周边的纽和荧光较弱分布于核仁内的点,表明不同植物间期核的rDNA染色质的组织模式相似.在每种植物的部分间期细胞都观察到点与纽相连或从纽发出的情况,而且点的数目越多纽就变得越小,点的有无和数目的多少与细胞的活性呈正相关.这些事实表明,纽代表了处于凝缩状态的非活性的rDNA染色质,点是由纽解凝缩而来,rDNA异染色质解凝缩形成点是植物rRNA基因活跃转录的细胞学表现,在同一物种中点的多少代表了间期核rDNA转录活性的强弱.我们的结果支持点是核仁内活性rRNA基因组织的结构单位及rRNA合成发生地点的推论.我们的结果还显示,不同植物间期核的rDNA染色质的组织也存在一些差异,其中核仁内点的最大数目有较大的不同.在所有供试植物的有丝分裂前中期细胞,45S rDNA探针在rDNA位点都产生了松散的信号块和许多点,表明植物的rDNA位点在有丝分裂前中期还有较活跃的转录.     

MicroRNA-329-mediated PTTG1 downregulation inactivates the MAPK signaling pathway to suppress cell proliferation and tumor growth in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a severe malignancy usually producing a poor prognosis and high mortality rate. MicroRNAs (miRNAs) have been reported in association with CCA; however, the role miR-329 plays in the CCA condition still remains unclear. Therefore, this study was conducted to explore the underlying mechanism of which miR-329 is influencing the progression of CCA. This work studied the differential analysis of the expression chips of CCA obtained from the Gene Expression Omnibus database. Next, to determine both the expression and role of pituitary tumor transforming gene-1 (PTTG1) in CCA, the miRNAs regulating PTTG1 were predicted. In the CCA cells that had been intervened with miR-329 upregulation or inhibition, along with PTTG1 silencing, expression of miR-329, PTTG1, p-p38/p38, p-ERK5/ERK5, proliferating cell nuclear antigen (PCNA), Cyclin D1, Bcl-2-associated X protein (Bax), B-cell CLL/lymphoma 2 (Bcl-2), and caspase-3 were determined. The effects of both miR-329 and PTTG1 on cell proliferation, cell-cycle distribution, and apoptosis were also assayed. The miR-329 was likely to affect the CCA development through regulation of the PTTG1-mediated mitogen-activated protein kinase (MAPK) signaling pathway. The miR-329 targeted PTTG1, leading to inactivation of the MAPK signaling pathway. Upregulation of miR-329 and silencing of PTTG1 inhibited the CCA cell proliferation, induced cell-cycle arrest, and subsequently promoted apoptosis with elevations in Bax, cleaved caspase-3, and total caspase-3, but showed declines in PCNA, Cyclin D1, and Bcl-2. Moreover, miR-329 was also found to suppress the tumor growth by downregulation of PTTG1. To summarize, miR-329 inhibited the expression of PTTG1 to inactivate the MAPK signaling pathway, thus suppressing the CCA progression, thereby providing a therapeutic basis for the CCA treatment.     

Yeast homotypic vacuole fusion requires the Ccz1-Mon1 complex during the tethering/docking stage

The function of the yeast lysosome/vacuole is critically linked with the morphology of the organelle. Accordingly, highly regulated processes control vacuolar fission and fusion events. Analysis of homotypic vacuole fusion demonstrated that vacuoles from strains defective in the CCZ1 and MON1 genes could not fuse. Morphological evidence suggested that these mutant vacuoles could not proceed to the tethering/docking stage. Ccz1 and Mon1 form a stable protein complex that binds the vacuole membrane. In the absence of the Ccz1-Mon1 complex, the integrity of vacuole SNARE pairing and the unpaired SNARE class C Vps/HOPS complex interaction were both impaired. The Ccz1-Mon1 complex colocalized with other fusion components on the vacuole as part of the cis-SNARE complex, and the association of the Ccz1-Mon1 complex with the vacuole appeared to be regulated by the class C Vps/HOPS complex proteins. Accordingly, we propose that the Ccz1-Mon1 complex is critical for the Ypt7-dependent tethering/docking stage leading to the formation of a trans-SNARE complex and subsequent vacuole fusion.     

植物着丝粒结构和功能的研究进展

着丝粒是真核生物有丝分裂和减数分裂染色体正确分离和传递所必需的染色体区域。十多年来, 已对包括拟南芥、水稻、玉米在内的一些植物的着丝粒进行了较深入的分子生物学研究。在不同的植物间, 着丝粒DNA的保守性很低, 呈现快速进化, 但着丝粒的DNA序列类型和组织方式基本相似, 一般是由夹杂排列着的卫星DNA串联重复阵列和着丝粒专一的反转录转座子构成。与着丝粒DNA相反, 着丝粒/着丝点的结构性和瞬时蛋白质在包括植物在内的真核生物中保守。与其他真核生物的情况一样, 拥有含着丝粒组蛋白H3(CENH3)的核小体是植物功能着丝粒染色质最基本的特征, CENH3在着丝粒染色质的识别和保持中起着关键作用。     

大型海藻裂片石莼藻粉对赤潮异弯藻光合作用抑制的研究

为了探究大型海藻裂片石莼(Ulva fasciata)防治赤潮的可行性,研究将赤潮异弯藻(Heterosigma aka-shiwo)分别暴露在浓度为0.6、1.2、2.4和4.8 g/L的裂片石莼藻粉中,观察赤潮异弯藻光合系统的响应.实验用植物效率分析法测定了赤潮异弯藻的光合效率,用透射电子显微镜法观察了赤潮异弯藻叶...