台湾青枣导管分子及其穿孔板研究

运用细胞图象分析系统及显微照相的方法对台湾青枣Z iziphus mauritiana次生木质部导管分子进行了观察研究。在台湾青枣的次生木质部导管分子中存在着许多不同的样式,并且导管分子穿孔板存在着3种类型:两端均为一个单穿孔板;一端为一个单穿孔板,另一端为梯状穿孔板;具纤毛的单穿孔板。分别对其进行了描述,并从导管分子个体发育与系统发育的角度进行了讨论,认为3种类型的穿孔板为导管分子穿孔板的系统演化提供了新的证据。     

基于不同方法的毛茛族(毛茛科)导管穿孔板比较研究

导管分子的演化与植物的进化相关联.毛茛科是联系基部被子植物和核心真双子叶植物的关键类群,对其导管穿孔板的研究具有重要的系统学意义.为研究毛茛科毛茛族不同属植物导管穿孔板类型及其与环境的相关性,该文利用新的扫描电子显微镜和半薄切片技术,对该族7属8种植物次生木质部导管状分子进行了比较观察.结果表明:木质部管状分子以单穿孔...     

Effect of molecular structure on the conductivity of amorphous carbohydrate-water-KCl mixtures in the supercooled liquid state

The effect of carbohydrate structure on the conductivity of low water content amorphous carbohydrate-water, and carbohydrate-water-KCl mixtures, has been measured using both direct current and alternating current techniques at temperatures in the supercooled liquid and glassy range, ranging from -40 to 80 degrees C. The structures included homologous mono-, di- and trisaccharides (glucose, maltose and maltotriose), a monosaccharide with no exocyclic hydroxymethyl group (xylose) and a second trisaccharide (raffinose). The KCl-mixtures contained 9.3% w/w water and 0.74% w/w KCl which resulted in calorimetric glass transition temperatures, T(g), in the range -29-19 degrees C. At this concentration conduction due to KCl dominated that due to intrinsic conductors originating from the carbohydrates and water. In the supercooled liquid region, as temperature, T, is reduced to T(g), the activation energy of the molar conductivity of KCl, Lambda(m), increased as described by a Vogel-Tamman-Fulcher-type equation, Lambda(m)=Lambda(m0)exp[B/(T-T(0))], where Lambda(m0), B and T(0) are constants. Comparison of the molar conductivity of KCl in the carbohydrate mixtures at T(g) with that in aqueous solutions showed that conductivity is, to varying extents, uncoupled from viscosity. The uncoupling increased in the order D-xylose相似文献   

Sem studies on vessels in ferns. 12. Marattiaceae, with comments on vessel patterns in eusporangiate ferns

Scanning electron microscopy (SEM) of tracheary elements of roots of five species from four genera of Marattiaceae and of the rhizome of one species revealed vessel elements present in all. The secondary wall framework of perforation plates is the same as that of lateral wall pitting for vessel elements in all species. Thus, no specialization is present in perforation plates of Marattiaceae compared to the simplified morphology of perforation plates of some leptosporangiate ferns (e.g., Dryopteridaceae, Polypodiaceae, and Pteridaceae). The difference between lateral wall pitting and perforation plates in tracheary elements of Marattiaceae cannot be seen by light microscopy (in which pit membranes are transparent), but is evident with SEM. Diversity in structure of perforation plates (especially the alternation of wide and narrow perforations within a plate) and presence of web-like pit membrane remnants are evident. Vessels are widespread in both leptosporangiate and eusporangiate ferns, although specialization in perforation plates (e.g., bars few and more widely spaced in lateral wall pitting of a given vessel element) is to be expected only in ferns of habitats with marked fluctuation in water availability. Vessels of Marattiaceae lack such specializations and are thus are correlated with the mesic habitats characteristic for the family.     

A survey of vessel dimensions in stems of tropical lianas and other growth forms

Summary Vessel dimensions (total diameter and length) were determined in tropical and subtropical plants of different growth forms with an emphasis upon lianas (woody vines). The paint infusion and compressed air methods were used on 38 species from 26 genera and 16 families in the most extensive survey of vessel length made to date. Within most stems there was a skewed frequency distribution of vessel lengths and diameter, with many short and narrow vessels and few long and wide ones. The longest vessel found (7.73 m) was in a stem of the liana (woody vine) Pithecoctenium crucigerum. Mean vessel length for 33 species of lianas was 0.38 m, average maximum length was 1.45 m. There was a statistically significant inter-species correlation between maximum vessel length and maximum vessel diameter. Among liana stems and among tree+shrub stems there were statistically significant correlations between stem xylem diameter and vessel dimensions. Lianas with different adaptations for climbing (tendril climbers, twiners, scramblers) were similar in their vessel dimensions except that scramblers tended to have shorter (but not narrower) vessels. Within one genus, Bauhinia, tendril climbing species had greater maximum vessel lengths and diameters than tree and shrub species. The few long and wide vessels of lianas are thought to hydraulically compensate for their narrow stem diameters. The many narrow and short vessels, which are present in the same liana stems, may provide a high resistance auxiliary transport system.     

Comparative Anatomical Studies on Vessel Elements of Chinese Ranunculaceae

The vessel elements in 77 species of 36 genera of Chinese Ranunculaceae were studied. The vessel elements of Ranunculaceae could be divided into primitive and more specialized groups on the basis of their morphological characters through clustering analysis. The most primitive type of the vessel elements was seen in Asteropyrum, and some vessel elements were considered more primitive, as in Paeonia, Trollius, Actaea, Helleborus, Souliea, Calathodes, Beesia, Caltha, Coptis, Kingdonia, Circaeaster, Adonis, Hepatica, than others. There was a marked difference between Paeonia and other genera of Ranunculaceae. The vessel elements of Paeonioideae and Helleboroideae with follicles were more primitive than Ranunculoideae with achenes. In Thalictroideae, .the vessel elements of Thalictrum with achenes were more specialized than other genera with follicles. All these findings coincided with the evolution of fruits. The character of evolution of vessel elements ran parallel with that of other parts of plant (flower, carpel, petiole, venation). The features of vessel elements in the same genus were at similar evolutional level, however, some difference between species do exist.     

Comparative Anatomical Studies on the Vessel Elements of Chinese Magnolia and Michelia

This paper deals mainly with comparative studies on elements of secondary xylem in 39 species of Chinese Magnolia and Michelia. The former plants present longer and slender vessels. Most of them have simple perforation and only a few scalariform perforation plates. In contrast, most of the Michelia species possess scalariform perforation plates and only one with simple perforation. The scalariform perforation plates of Magnolia species, if present, exhibit more bars than that of Michelia With few exceptions, there is no spiral thickening on the vessel wall in Magnolia, whereas in Michelia it is lust the opposite. In addition, some other differences in vessel elements between these two genera are also discussed.     

Regulation of blood vessel sprouting

Blood vessels are essential conduits of nutrients and oxygen throughout the body. The formation of these vessels involves angiogenic sprouting, a complex process entailing highly integrated cell behaviors and signaling pathways. In this review, we discuss how endothelial cells initiate a vessel sprout through interactions with their environment and with one another, particularly through lateral inhibition. We review the composition of the local environment, which contains an initial set of guidance cues to facilitate the proper outward migration of the sprout as it emerges from a parent vessel. The long-range guidance and sprout stability cues provided by soluble molecules, extracellular matrix components, and interactions with other cell types are also discussed. We also examine emerging evidence for mechanisms that govern sprout fusion with its target and lumen formation.     

细枝木麻黄导管分子及穿孔板解剖学研究

运用细胞图象分析系统和显微照相的方法对细枝木麻黄(CasuarinacunninghamianaMiq.)次生木质部导管分子进行了观察研究。细枝木麻黄次生木质部导管分子有3种类型,即两端具尾导管、一端具尾导管和无尾导管。导管分子穿孔板有4种类型:两端均为梯状穿孔板、一端为单穿孔板,另一端为梯状穿孔板、两端均为单穿孔板、一梯状穿孔板与一单穿孔板位于同一端壁两侧相互对应以及一些过渡类型穿孔板。根据观察结果,分析了各类型穿孔板之间的演化关系。     

The effect of SEM preparation on pit membrane remnants in vessel element end-walls of primitive angiosperms

Scanning electron microscope (SEM) is necessary to demonstrate presence or absence of pit membranes in possible perforations or the type of pit membrane remnants in perforations in vessel element end-walls of angiosperms, but it was unconfirmed and questionable whether pit membrane absence in pits was affected by the processing and handling before SEM observations. To solve this question, the secondary xylem of four woody species from primitive angiosperms, Illicium henryi Diels. (Illiciaceae), Schisandra rubriflora (Franch.) Rehd. et Wils. (Schisandraceae), Tetracentron sinensis Oliv. and Trochodendron aralioides Sieb. & Zucc. (Trochodendraceae) was chosen and the following techniques were used: (1) fresh materials were examined in low-vacuum with ESEM. (2) Air-dried materials were examined both in low- and high-vacuum with ESEM. (3) Fresh materials fixed in several different fixatives were observed in low-vacuum, respectively. (4) Smooth surface of the material by paraffin section methods was examined in high-vacuum. (5) Materials treated by Jeffrey's Fluid were observed in high-vacuum.Pit membranes and remnants in perforations of fresh material were little different from that of treated materials. Absence of the pit membrane in perforations (pits) in the end-wall was not attributed to the processing and handling. Information of pit membranes and remnants in perforations in end-wall based on the SEM observation might be validly claimed.     

黄三七( 毛茛科) 茎次生木质部导管穿孔板的研究*

利用扫描电子显微镜对东亚特有植物黄三七( Souliea vaginata (Maxim. ) Franch. ) 茎的次生木质部
离析材料进行了观察, 结果表明, 黄三七茎次生木质部中的导管分子端壁上具网状穿孔板( 麻黄式穿孔
板) 、梯状穿孔板、网状- 梯状混合穿孔板、网状- 梯状- 单穿孔混合型穿孔板、梯状- 单穿孔混合型穿
孔板及单穿孔板, 同时也观察到了端壁多穿孔板和侧壁穿孔板, 并对不同类型穿孔板中纹孔膜的残留也进
行了观察。其中, 网状穿孔板、各种过渡类型的穿孔板均为毛茛科植物中首次报道。根据观察结果, 对导
管分子穿孔板的演化及黄三七属植物的系统位置进行了分析。     

Neuronal action on the developing blood vessel pattern

The nervous system relies on a highly specialized network of blood vessels for development and neuronal survival. Recent evidence suggests that both the central and peripheral nervous systems (CNS and PNS) employ multiple mechanisms to shape the vascular tree to meet its specific metabolic demands, such as promoting nerve-artery alignment in the PNS or the development the blood brain barrier in the CNS. In this article we discuss how the nervous system directly influences blood vessel patterning resulting in neuro-vascular congruence that is maintained throughout development and in the adult.     

黄三七(毛茛科)茎次生木质部导管穿孔板的研究

利用扫描电子显微镜对东亚特有植物黄三七（Souliea vaginata（Maxim.） Franch.）茎的次生木质部离析材料进行了观察,结果表明,黄三七茎次生木质部中的导管分子端壁上具网状穿孔板（麻黄式穿孔板）、梯状穿孔板、网状-梯状混合穿孔板、网状-梯状-单穿孔混合型穿孔板、梯状-单穿孔混合型穿孔板及单穿孔板,同时也观察到了端壁多穿孔板和侧壁穿孔板,并对不同类型穿孔板中纹孔膜的残留也进行了观察。其中,网状穿孔板、各种过渡类型的穿孔板均为毛茛科植物中首次报道。根据观察结果,对导管分子穿孔板的演化及黄三七属植物的系统位置进行了分析。     

The effect of temperature on membrane hydraulic conductivity

The objective of this study was to use the temperature dependence of water permeability to suggest the physical mechanisms of water transport across membranes of osmotically slowly responding cells and to demonstrate that insight into water transport mechanisms in these cells may be gained from easily performed experiments using an electronic particle counter. Osmotic responses of V-79W Chinese hamster fibroblast cells were measured in hypertonic solutions at various temperatures and the membrane hydraulic conductivity was determined. The results were fit with the general Arrhenius equation with two free parameters, and also fit with two specific membrane models each having only one free parameter. Data from the literature including that for human bone marrow stem cells, hamster pancreatic islets, and bovine articular cartilage chondrocytes were also examined. The results indicated that the membrane models could be used in conjunction with measured permeability data at different temperatures to investigate the method of water movement across various cell membranes. This approach for slower responding cells challenges the current concept that the presence of aqueous pores is always accompanied by an osmotic water permeability value, P(f)>0.01 cm/s. The possibility of water transport through aqueous pores in lower-permeability cells is proposed.     

Spiral Thickenings of Vessel Elements in Magnoliaceae in China

Spiral thickenings in the inner walls of vessels were studied in 10 genera 69 species of Magnoliaceae in China under scanning electron microscopic observation. Spiral thickenings were found in some species. The majority of these species showed complete thickenings of the inner wall, however, in some of which the spiral thickenings were less obvious at both ends. In others, these spiral thickenings existed only in the middle portion, uniformly or irregularly distributed.     

Synthesis, structures and conductivity properties of silver 3-sulfobenzoate coordination polymers

Four coordination polymers based on Ag^I/3-sulfobenzoate/N-donor ligands, [Ag₂Na₂(3-sb)₂(H₂O)₇]_n (1), {[Ag₂(3-sb)(apy)]·(H₂O)}_n (2), {[Ag₂(4,4′-bipy)₂(H₂O)₃]·[Ag₂(4,4′-bipy)₂(H₂O)₂]·2(3-sb)·4(H₂O)}_n (3) and {[Ag(3-sb)(bpe)(H₂O)][Ag(bpe)(H₂O)]·3(H₂O)}_n (4) where 3-sb is 3-sulfobenzoate, apy is 2-aminopyridine, bipy is 4,4′-bipyridine and bpe is 1,2-bis(4-pyridyl)ethylene, were prepared and characterized, and their fluorescence and electric conductivity properties were studied. Complex 1 is a 3D architecture in which 3-sb ligands exhibit μ₄-κ¹(O1,O2-Ag): κ¹(O3,O5-Na) trans-trans coordination mode. The molecular structure of 2 is a 2D layer. Complexes 3 and 4 are cation-anion species and 1D polymers. In these complexes hydrogen bonds provide additional assembly forces, giving 3D hydrogen bonding networks for 1 and 3, and 2D layers for 2 and 4. Abundant weak interactions, such as Ag-Ag interactions in 1-3, Ag-π interactions in 1-4, π-π interactions in 1, 3-4, and C-H···π interactions in 3-4, also can be found. The weak interactions are strongly related to the fluorescence and electric conductivity properties, providing the way for understanding the relationship between structures and properties.     

芒果次生木质部导管分子的观察

运用细胞图象分析系统及显微照相的方法对芒果(Mangifera indicaL.)次生木质部不同的导管分子进行了观察。并且对这些导管分子的构造、进化趋势以及同一导管分子上的特殊结构进行了详细的讨论。     

The effect of extracellular conductivity on electroporation-mediated molecular delivery

In this work, the effect of extra-cellular conductivity on electroporation-mediated molecular delivery efficiency is investigated. A numerical model combining the Smoluchowski equation for membrane permeabilization and the Nernst–Planck equations for ion transport is used to simulate the evolution of ion concentration spatially and temporally. The results are compared with and used to interpret trends observed from previous experimental measurements. Agreements are found which suggest the critical importance of electrophoretic transport. This mechanism controls delivery efficiency on the quantitative level. Meanwhile, a simple formula is developed to predict the molecular content delivered via electrophoresis. The formula can be used as a compact model which provides good approximation to the full numerical model while avoiding the computational cost.     

Characterization of DNA degradation using direct current conductivity and dynamic dielectric relaxation techniques

The purpose of this study was to evaluate DNA degradation upon thermal heating using dielectric relaxation and direct current (DC) conductivity methods. Herring sperm DNA, human growth hormone (HgH) plasmid DNA, and secreted alkaline phosphatase (SEAP) plasmid DNA were used as the examples. DNA was heated at 80°C for 1 hour. The dielectric relaxation spectra as a function of the applied field frequency were measured for HgH DNA at 0.5 hours and at 1 hour. The frequency range covered was from 10 kHz to 100 kHz. The DC conductivity measurements were made for all 3 kinds of DNA at 4 time points: 0 hours, 0.5 hours, 0.75 hours, and 1 hour. At each time point the DC conductivity was measured for each sample as a function of concentration via water dilution. The results show that the dielectric relaxation method is less sensitive in characterizing heat-driven DNA degradation. Conversely, DC conductivity is very sensitive. The semiquantitative dependence of the conductivity upon heating suggests that DNA degradation involves more than plasmid DNA nicking. Double strand and single strand breaks may also occur. In addition, herring sperm DNA, HgH DNA, and SEAP DNA, though similar in their DC conductivity functional forms upon dilution, exhibit significant differences in their responses to sustained heating.     

蜈蚣草导管分子的观察

对蜈蚣草(Pteris vittata)叶轴中导管分子进行了观察。结果表明,其导管分子十分细长,均具长、且十分倾斜的梯状穿孔板,穿孔没有纹孔膜的残余,与侧壁上的梯纹纹孔有着明显的差异。