小麦生理型雄性不育系微丝骨架和胼胝质的变化与其相关基因的表达分析

【目的】研究生理型雄性不育小麦花粉细胞内微丝和胼胝质的结构及其相关基因的表达,并揭示其与生理型雄性不育的关系,为进一步研究化学杂交剂SQ-1诱导小麦生理型雄性不育的机理提供一定的理论依据。【方法】以化学杂交剂SQ-1诱导的生理型雄性不育系ms(A)-西农1376及对应正常可育系(A)-西农1376为试材,用TRITC-phalloidin标记细胞内微丝,苯胺蓝标记胼胝质,qRT-PCR技术分别对肌动蛋白解聚因子TaADF（Actin depolymerizing factor）、类葡聚糖合成酶TaGSL（Glucan synthase-like）进行差异表达分析。【结果】(1)在减数分裂前期Ⅰ、中期Ⅰ、后期Ⅰ这三个时期,生理型雄性不育系花粉细胞的微丝结构与可育系没有显著差异：前期Ⅰ,微丝分布于整个细胞质中,细胞核区域也可见少量微丝环绕细胞核;中期Ⅰ,微丝分布在细胞质中,在形成纺锤体部位染色更深,形成纺锤体微丝,由细胞两极发出的纺锤体微丝伸向赤道板;后期Ⅰ,在向两极移动的染色体的中间部位染色较深,微丝分布较多。(2)在早末期Ⅰ,与可育系相比,不育系花粉细胞没有形成清晰且明显可见的中国灯笼状成膜体微丝结构,且在细胞中线部位亦没有清晰可见的微丝累积。(3)晚末期Ⅰ,可育系花粉细胞在形成细胞板的部位是线性的、平滑的,成膜体微丝消失,而不育系花粉细胞在形成细胞板的部位形成了很大的缝隙,同时,可育系胼胝质在细胞板处的沉积比较平滑,而不育系胼胝质在细胞板处的沉积较可育系相比缺乏,并且是褶皱的、有裂纹的。(4)四分体时期,可育系花粉可见围绕细胞核的辐射状微丝,不育系花粉细胞中微丝呈模糊状态,并且不育系中胼胝质染色的整体荧光强度较可育系减弱。利用实时荧光定量PCR技术分析肌动蛋白解聚因子TaADF和类葡聚糖合成酶TaGSL在减数分裂期的相对表达量,结果发现,不育系中TaADF的相对表达量是可育系的4.28倍,由于TaADF表达量上调,加剧了细胞内微丝解聚,微丝结构受到破坏,同时不育系中TaGSL表达量下降,只有可育系的0.83倍,胼胝质的沉积也受到影响。【结论】TaADF在不育系中上调表达,破坏了细胞内微丝的正常结构,使微丝不能正常行使其功能,进而可能导致花药发育中与育性相关的某些代谢通路等受到影响。与此同时,微丝结构的破坏导致细胞板形成出现异常也可能是引起胼胝质在细胞板处沉积受到影响的一个重要原因。因此,微丝和胼胝质的异常变化与化学杂交剂SQ-1诱导的生理型雄性不育密切相关。     

大泷六线鱼链球菌病的病原及其防治

2008年9月,辽宁省某养殖场养殖的大泷六线鱼Hexagrammos otakii暴发链球菌病,患病鱼鳃盖内侧发红,体表无明显症状。对病鱼进行细菌分离,从脑部分离出纯度较高的细菌,并经人工感染试验确定了该菌的致病性。对该细菌进行形态观察、生理生化特征比较及16S rRNA分子鉴定,测定了16S rRNA基因序列,并构建系统发育树。结果表明,该致病菌（ZG0990）与海豚链球菌Streptococcus iniae的相似性最高（99.48%）。药敏试验表明,该致病菌对青霉素G、先锋Ⅴ和呋喃妥因等多种药物敏感,并且将青霉素G按质量分数为0.1%的量拌饲投喂病鱼,取得了良好的治疗效果。     

光对美洲蛙肌肉纤维衍射强度的分布研究

肌原纤维是由粗丝和细丝重迭而成的Ａ带和只含细丝的Ⅰ带组成，形成了天然光栅，因此可用光学方法探讨肌原纤维分子结构及其动力学问题。试验表明，单色光通过美洲蛙肌原纤维后，衍射光左右两端为非对称性，且左右条纹锋值间隔随肌原纤维节长度增大而减小。肌肉运动有张有弛，于是肌原纤维长度有变异，共变异与非对称有关。当肌原纤维长度增加时，左右两端强度差异变大，而相对应条纹的锋值间隔距离变小。这一现象与布拉格方程和折射     

萱藻丝状体诱导培养及采苗研究

对萱藻Scytosiphon lomentaria丝状体诱导培养及采苗进行了研究。在室内培养条件下,从萱藻盘状孢子体上获得了丝状体并游离培养成直径为1～2cm的藻团,采用将丝状体切碎的方法获得大量盘状孢子体,盘状孢子体经生长后在10℃和15℃下形成单室孢子囊并放出游孢子,以维尼纶绳为附着基进行孢子采集,置于10℃下培养35d后获得藻体长度为0．5～1.0cm的萱藻幼苗。结果表明：盘状孢子体在藻体直径达到100μm后开始形成丝状体,20℃下丝状体形成的时间早、数量多,生长速度快,切碎后的丝状体在20℃下5d后开始形成盘状体,20d后其形成率达到100％;15℃下10d后形成盘状体,20d后其形成率为65％;10℃下12d后才形成盘状体,20d后的形成率仅为40％。     

FINE STRUCTURE OF A DIATOM CENTROSOME

The centrosome of the diatom Surirella ovalis is a dense spherical structure 500 mmicro in diamneter with filaments 15 mmicro in diamneter connected to it. The interior is filled with uniform granules but does not contain a typical centriole or clear area. The filaments emanating from it resemble the filaments of the mitotic apparatus, but they are present during interphase and appear to terminate at pores in the nuclear envelope.     

Conducting polyaniline filaments in a mesoporous channel host

Conducting filaments of polyaniline have been prepared in the 3-nanometer-wide hexagonal channel system of the aluminosilicate MCM-41. Adsorption of aniline vapor into the dehydrated host, followed by reaction with peroxydisulfate, leads to encapsulated polyaniline filaments. Spectroscopic data show that the filaments are in the protonated emeraldine salt form, and chromatography indicates chain lengths of several hundred aniline rings. The filaments have significant conductivity while encapsulated in the channels, as measured by microwave absorption at 2.6 gigahertz. This demonstration of conjugated polymers with mobile charge carriers in nanometer channels represents a step toward the design of nanometer electronic devices.     

Divergence of quaternary structures among bacterial flagellar filaments

It has been widely assumed that the atomic structure of the flagellar filament from Salmonella typhimurium serves as a model for all bacterial flagellar filaments given the sequence conservation in the coiled-coil regions responsible for polymerization. On the basis of electron microscopic images, we show that the flagellar filaments from Campylobacter jejuni have seven protofilaments rather than the 11 in S. typhimurium. The vertebrate Toll-like receptor 5 (TLR5) recognizes a region of bacterial flagellin that is involved in subunit-subunit assembly in Salmonella and many other pathogenic bacteria, and this short region has diverged in Campylobacter and related bacteria, such as Helicobacter pylori, which are not recognized by TLR5. The driving force in the change of quaternary structure between Salmonella and Campylobacter may have been the evasion of TLR5.     

Single-molecule speckle analysis of actin filament turnover in lamellipodia

Lamellipodia are thin, veil-like extensions at the edge of cells that contain a dynamic array of actin filaments. We describe an approach for analyzing spatial regulation of actin polymerization and depolymerization in vivo in which we tracked single molecules of actin fused to the green fluorescent protein. Polymerization and the lifetime of actin filaments in lamellipodia were measured with high spatial precision. Basal polymerization and depolymerization occurred throughout lamellipodia with largely constant kinetics, and polymerization was promoted within one micron of the lamellipodium tip. Most of the actin filaments in the lamellipodium were generated by polymerization away from the tip.     

Magnetosomes are cell membrane invaginations organized by the actin-like protein MamK

Magnetosomes are membranous bacterial organelles sharing many features of eukaryotic organelles. Using electron cryotomography, we found that magnetosomes are invaginations of the cell membrane flanked by a network of cytoskeletal filaments. The filaments appeared to be composed of MamK, a homolog of the bacterial actin-like protein MreB, which formed filaments in vivo. In a mamK deletion strain, the magnetosome-associated cytoskeleton was absent and individual magnetosomes were no longer organized into chains. Thus, it seems that prokaryotes can use cytoskeletal filaments to position organelles within the cell.     

Isolation of filaments from brain

A method is presented for the isolation of filaments of 90-angstrom diameter from the white matter of bovine brain by first floating the myelinated axons in a centrifugal field and then fractionating the axons on a series of density gradients. This results in a fraction that contains two types of bundles of filaments but few other constituents. The filaments are stable over a wide range of temperatures and at both low and high ionic strength. Their density and their resistance to digestion by ribonuclease and deoxyribonuclease indicate that they are primarily protein. The molecular weight of the subunit is approximately 60,000. The protein does not comigrate with microtubule protein and does not bind cholcicine or nucleotides.     

Mitochondrial-satellite and circular DNA filaments in yeast

Mitochondrial DNA of Saccharomyces cerevisiae contains a satellite DNA (density, 1.682) that appears to exist as open-ended filaments at least 5 microns long. DNA from intact cells contains circular filaments whose lengths vary from 0.5 to 7 microns, with a great majority at 1.95 microns. The circular DNA has a density similar to that of the major nuclear peak (1.697). When heat-denatured mitochondrial-satellite DNA is renatured, it cross-links to form a molecule that is larger than the native molecule. The formation of cross-links results in hypersharpening of the density profiles in cesium chloride and also leads to failure to pass Millipore filter paper.     

Cortical constriction during abscission involves helices of ESCRT-III-dependent filaments

After partitioning of cytoplasmic contents by cleavage furrow ingression, animal cells remain connected by an intercellular bridge, which subsequently splits by abscission. Here, we examined intermediate stages of abscission in human cells by using live imaging, three-dimensional structured illumination microscopy, and electron tomography. We identified helices of 17-nanometer-diameter filaments, which narrowed the cortex of the intercellular bridge to a single stalk. The endosomal sorting complex required for transport (ESCRT)-III co-localized with constriction zones and was required for assembly of 17-nanometer-diameter filaments. Simultaneous spastin-mediated removal of underlying microtubules enabled full constriction at the abscission site. The identification of contractile filament helices at the intercellular bridge has broad implications for the understanding of cell division and of ESCRT-III-mediated fission of large membrane structures.     

杜仲叶橡胶丝网络结构的研究

除去非胶成分使纯粹的橡胶丝完全暴露出来，可得到杜仲全叶的胶丝网络体系。通过观察和比较，可见杜仲叶中的胶丝网络结构与叶脉的网络结构完全一致，证明胶丝是叶脉的组成部分。同时观察到杜仲叶缘锯齿的骨架主要由两股胶丝组成，胶丝网络的分枝形式为反向汇集型，叶尖附近的叶缘上排列着发育不平衡的锯齿结构     

Twisting motions of sunspot penumbral filaments

The penumbra of a sunspot is composed of numerous thin, radially extended, bright and dark filaments carrying outward gas flows (the Evershed flow). Using high-resolution images obtained by the Solar Optical Telescope aboard the solar physics satellite Hinode, we discovered a number of penumbral bright filaments revealing twisting motions about their axes. These twisting motions are observed only in penumbrae located in the direction perpendicular to the symmetry line connecting the sunspot center and the solar disk center, and the direction of the twist (that is, lateral motions of intensity fluctuation across filaments) is always from limb side to disk-center side. Thus, the twisting feature is not an actual twist or turn of filaments but a manifestation of dynamics of penumbral filaments with three-dimensional radiative transfer effects.     

Alzheimer's disease: insolubility of partially purified paired helical filaments in sodium dodecyl sulfate and urea

A method is described for the partial purification of the paired helical filaments that accumulate progressively in human neurons in Alzheimer's disease (senile dementia). Paired helical filaments have unusual solubility characteristics, including insolubility in sodium dodecyl sulfate, urea, reducing agent, and guanidine, which prevent analysis of their molecular composition by gel electrophoresis. The paired helical filaments appear to contain covalent bonds other than disulfide, which cross-link individual filaments into a rigid intracellular polymer. Thus, paired helical filaments appear to represent an example in neurons of an insoluble cross-linked protein. Covalently cross-linked protein polymers occur in lens senile cataracts and in terminally differentiated skin keratinocytes, suggesting that there may be a common mechanism for remodeling some structural proteins during cell aging.     

Direct redox regulation of F-actin assembly and disassembly by Mical

Different types of cell behavior, including growth, motility, and navigation, require actin proteins to assemble into filaments. Here, we describe a biochemical process that was able to disassemble actin filaments and limit their reassembly. Actin was a specific substrate of the multidomain oxidation-reduction enzyme, Mical, a poorly understood actin disassembly factor that directly responds to Semaphorin/Plexin extracellular repulsive cues. Actin filament subunits were directly modified by Mical on their conserved pointed-end, which is critical for filament assembly. Mical posttranslationally oxidized the methionine 44 residue within the D-loop of actin, simultaneously severing filaments and decreasing polymerization. This mechanism underlying actin cytoskeletal collapse may have broad physiological and pathological ramifications.     

Role of formins in actin assembly: nucleation and barbed-end association

Nucleation of branched actin filaments by the Arp2/3 complex is a conserved process in eukaryotic cells, yet the source of unbranched actin filaments has remained obscure. In yeast, formins stimulate assembly of actin cables independently of Arp2/3. Here, the conserved core of formin homology domains 1 and 2 of Bni1p (Bni1pFH1FH2) was found to nucleate unbranched actin filaments in vitro. Bni1pFH2 provided the minimal region sufficient for nucleation. Unique among actin nucleators, Bni1pFH1FH2 remained associated with the growing barbed ends of filaments. This combination of properties suggests a direct role for formins in regulating nucleation and polarization of unbranched filamentous actin structures.     

不同类型糯玉米自交系花丝活力比较

选用不同类型的5个糯玉米自交系,测定了其花丝伸长速度、花丝抽出苞叶数目以及吐丝后不同时期授粉结实数,结果表明:无秃尖类型自交系花丝伸长速度较一致,花丝抽出苞叶的时间较早、集中,花丝伸长1 cm后的第3天,花丝就全部抽出苞叶;第2天授粉结实数就显著增加,第3天授粉结实数接近于最大值;第5天、第6天后结实数开始显著下降。有秃尖、长穗型自交系的花丝伸长速度在试验的6 d中缓慢提高,抽出苞叶的花丝数目较少,持续时间长,前7 d的结实数缓慢升高,后逐渐降低。因此,在糯玉米组合选配时,选择少秃尖自交系作母本,制种时尽可能使父本盛花期在母本吐丝后的第3天至第5天,从而提高制种产量。     

Expression and characterization of a functional myosin head fragment in Dictyostelium discoideum

The isolated head fragment of myosin is a motor protein that is able to use energy liberated from the hydrolysis of adenosine triphosphate to cause sliding movement of actin filaments. Expression of a myosin fragment nearly equivalent to the amino-terminal globular head domain, generally referred to as subfragment 1, has been achieved by transforming the eukaryotic organism Dictyostelium discoideum with a plasmid that carries a 2.6-kilobase fragment of the cloned Dictyostelium myosin heavy chain gene under the control of the Dictyostelium actin-15 promoter. The recombinant fragment of the myosin heavy chain was purified 2400-fold from one of the resulting cell lines and was found to be functional by the following criteria: the myosin head fragment copurified with the essential and regulatory myosin light chains, decorated actin filaments, and displayed actin-activated adenosine triphosphatase activity. In addition, motility assays in vitro showed that the recombinant myosin fragment is capable of supporting sliding movement of actin filaments.     

金银花与山银花的性状差异及鉴别方法

综述了金银花的植物来源忍冬和山银花的植物来源灰毡毛忍冬、红腺忍冬、华南忍冬和黄褐毛忍冬,并对其来源植物花蕾性状在表面、萼筒、萼齿、花丝和花蕾大小等方面的特点加以区分,从内部显微结构和挥发油、黄酮类化合物、有机酸类化合物等化学成分对二者进行比较,同时结合DNA指纹图谱的研究,寻找金银花与山银花的区别,形成一套多元多息鉴别...