细胞壁在细胞极性建立和胚胎发生中的作用

植物细胞壁是一个活性的动态结构,其结构层次与组分随着发育进程而发生变化,且广泛参与细胞的各项生命活动,特别是在参与细胞命运决定、充当细胞发育信使、调控植物胚胎早期极性建立以及模式建成等方面发挥重要作用。     

Entropy production and the Second Law in photosynthesis

An assertion that the primary photochemistry of photosynthesis can violate the Second Law of thermodynamics in certain efficient systems has been put forward by Jennings et al., who maintain their position strongly despite an argument to the contrary by Lavergne. We identify a specific omission in the calculation of Jennings et al. and show that no violation of the Second Law occurs, regardless of the photosynthetic efficiency.     

高等植物小孢子胚发生的启动

高等植物小孢子在受到胁迫时能改变正常的花粉发育途径而启动胚发生途径.小孢子胚发生的启动主要包括胚发生的诱导、对胁迫的细胞应答和抑制花粉发育程序.目前,国内外对于小孢子胚发生研究大多限于形态学观察,对小孢子由正常花粉发育途径转向胚发生途径过程中所涉及的相关分子机制缺乏系统报道,而上述研究是精确、高效诱导小孢子胚发生的关键.结合目前最新研究,对小孢子胚发生的早期事件,尤其是小孢子启动胚发生的生理生化和分子机制作一简要论述.以期为相关研究提供参考.     

陆地棉体细胞胚胎发生与植株再生

利用陆地棉品种下胚轴为外植体进行体外培养研究。激素和品种是影响愈伤诱导和胚胎发生的主要因素。去除激素后胚性愈伤在固体培养基上只能形成少量的成熟胚。悬浮培养是获得大量成熟胚的中间步骤。悬培两周后,悬培物转到固体培养基上促进胚状体成熟,30—60目之间的悬培物比大于30目的悬培物易形成成熟胚。KT 0.1ppm、Zea 0.1ppm分别有效地促进了胚状体成熟。活性碳250mg/L、NAA 0.1ppm、IBA 0.1ppm和IAA 0.1ppm能使胚状体萌发并健壮生长。目前已得到100多株幼苗,大苗已达八片真叶。     

蔷薇科植物体细胞胚胎发生及影响因素研究进展

总结了近30年来蔷薇科植物体细胞胚胎发生及影响因素的研究进展。蔷薇科植物体胚发生多数是直接发生途径和间接发生途径同时存在,但以间接发生途径为主。合子胚作为外植体明显好于营养器官作为外植体。诱导体胚发生的植物生长素类调节剂以NAA、2,4-D为主,细胞分裂素类调节剂以6-BA为主,少数植物种类的体胚诱导需要添加KT。冷处理对蔷薇科植物的体胚分化有效。光照对蔷薇科植物的体胚发生没有显著的影响,有时光照会抑制体胚发生。今后应逐步开展对蔷薇科植物体细胞胚胎发生的生理、生化及分子机理的研究,这在蔷薇科植物的新品种培育、遗传改良、优良单株的离体扩殖等具有重要意义。     

Studies on Fertilization and Embryogenesis of Red Vinespinach (Basella rubra L.)

This paper presents detailed report on the process of fertilization and the develop- ment of embryo and endosperm of Basella rubra L. The results obtained are summarized as follows: About 4–6 hours after anthesis a great deal pollen grains germinated on the stig- ma; 6–11 hours, the pollen tube passed through the style; 11–16 hours, the pollen tube reached the ovary cavity. About 16–18 hours, one sperm nucleus entered into the egg and the other one entered into the secondary nucleus. In most cases, after 16–24 hours the double fertilization had completed. After 2–8 days, two-celled proembryo was first shown. Finally, the proembryo gave rise to multicellular globular embryo proper. The development of the embryo of Basella rubra L. conforms to the Asterad type. Whether the Asterad type had a high frequency needs further to be studied. Although the fertilization of the sperm nucleus with the secondary nucleus began later, the fusion of two sexual nuclei and the development of the endosperm proceeded often quickly. After 20 hours, the free nuclei period began, and after 2–4 days the free nuclei of endosperm were rapidly formed. The endosperm of Basella rubra L. is a nuclear type. And at the time When the seed had ripened the endosperm tissues were all absorbed by the developing embryo. The author observed that there are different distributions of the vegetative nucleus and two sperms in the pollen tube, and that two sperms entered a egg or secondary nucleus. The changes of the starch accumulated and distributed et al. in the floral organs are also studied and discussed.     

Entropy in evolution

Daniel R. Brooks and E. O. Wiley have proposed a theory of evolution in which fitness is merely a rate determining factor. Evolution is driven by non-equilibrium processes which increase the entropy and information content of species together. Evolution can occur without environmental selection, since increased complexity and organization result from the likely capture at the species level of random variations produced at the chemical level. Speciation can occur as the result of variation within the species which decreases the probability of sharing genetic information. Critics of the Brooks-Wiley theory argue that they have abused terminology from information theory and t thermodynamics. In this paper I review the essentials of the theory, and give an account of hierarchical physical information systems within which the theory can be interpreted. I then show how the major conceptual objections can be answered.     

抗寒性小麦品种逆境下化学反应与扩散过程的热力学分析

本文以典型的冬性小麦品种及春性品种为对象，利用示踪技术，通过液闪计数据方法，测定了低温胁迫下不同品种膜脂的代谢情况。根据实验的结果，从热力学的角度对低温胁迫下生物脂膜上的化学反应及扩散过程进行了分析，阐明了植株逆境下各种反应降低的原因，丰富了逆境生理研究的内容。     

Embryogenesis and seed development in Sinomanglietia glauca (Magnoliaceae)

The development of the floral bud, especially the ovule and seed coat, of Sinomanglietia glauca was observed. Floral buds were covered by eight to nine hypsophyll pieces. The hypsophyll nearest the tepal was closed completely and characterized by two arrays of densely stained cells with dense cytoplasm, which split longitudinally at flowering. The perianth consisted of 16 tepals arranged in three whorls. The gynoecium was composed of numerous apocarpous carpels; the ovule was anatropous with two integuments. Embryogenesis was of the Polygonum type, and the endosperm was nuclear. The inner integument degenerated during seed development. The seed of S. glauca had an endotestal seed coat comprised of a sclerotic layer derived from the inner adaxial epidermis of the outer integument and a sarcotesta derived mainly from the middle cells between the inner and outer epidermis of the outer integument. The embryo developed normally, so embryogenesis is not the cause of difficult regeneration.     

Embryogenesis in flowering plants: Recent approaches and prospects

The overall architectural pattern of the mature plant is established during embryogenesis. Very little is known about the molecular processes that underlie embryo morphogenesis. Last decade has, nevertheless, seen a burst of information on the subject. The synchronous somatic embryogenesis system of carrot is largely being used as the experimental system. Information on the molecular regulation of embryogenesis obtained with carrot somatic embryos as well as observations on sandalwood embryogenic system developed in our laboratory are summarized in this review. The basic experimental strategy of molecular analysis mostly relied on a comparison between genes and proteins being expressed in embryogenic and non-embryogenic cells as well as in the different stages of embryogenesis. Events such as expression of totipotency of cells and establishment of polarity which are so critical for embryo development have been characterized using the strategy. Several genes have been identified and cloned from the carrot system. These include sequences that encode certain extracellular proteins (EPs) that influence cell proliferation and embryogenesis in specific ways and sequences of the abscisic acid (ABA) inducible late embryogenesis abundant (LEA) proteins which are most abundant and differentially expressed mRNAs in somatic embryos. That LEAs are expressed in the somatic embryos of a tree flora also is evidenced from studies on sandalwood. Several undescribed or novel sequences that are enhanced in embryos were identified. A sequence of this nature exists in sandalwood embryos was demonstrated using aCuscuta haustorial (organ-specific) cDNA probe. Somatic embryogenesis systems have been used to assess the expression of genes isolated from non-embryogenic tissues. Particular attention has been focused on both cell cycle and histone genes     

Somatic Embryogenesis and Plant Regeneration from Papaya Suspension Cultures

Compact embryogenetic calli were obtained from explants on P3 medium after 4 weeks of culture and high-frequency somatic embryogenesis occurred after these calli were transferred into suspension culture. Experimental data showed that low level (0.2%W/V) of activated charcoal had beneficial effects on somatic embryogenesis. Abundant calli on P4 medium however, showed no embryogenesis. On the other hand, callus induction and somatic embryogenesis varied with different rarities of exptants. The efficiency of somatic embryogenesis was much higher, if roots were used as explants, whereas stems were more suitable for callus formation Mature somatic embryos with cotyledons were cultured on MS medium containing different plant hormones. The optimum medium for germination and growth of entire plantlet was Mso medium. The somatic embryos on MS2, MS and MS3 media germinated rapidly, but formed excessive callus from the surface of germinating embryos.     

Embryogenesis and plant regeneration from callus cultures derived from unpollinated ovaries of Hyoscyamus muticus L.

Unpollinated ovaries of Hyoscyamus muticus L. (commonly known as Egyptian henbane) were cultured on Murashige and Skoog and Bourgin and Nitsch media supplemented with various growth hormones to study the organogenesis, embryogenesis and regeneration of plantlets. Embryogenesis was reported for callus grown on both media containing 0.05 mg/l α-naphthaleneacetic acid and 0.5 mg/l 6-benzylaminopurine. Differentiation of roots and shoots from the calli also occurred in these media. Albinism or chlorophyll deficiency and variation in ploidy level were observed among the ovary-derived plantlets. Received: 7 April 1997 / Revised received: 2 August 1997 / Accepted: 2 September 1997     

结球甘蓝游离小孢子胚胎发生

以结球甘蓝品种“强夏”为材料进行游离小孢子培养,对与胚胎发生关系密切的因子进行探讨。研究结果表明,在盛花前期取材最适宜;单核晚期至双核期的小孢子才能发育成胚状体;含17%蔗糖的培养液在培养初期有利于小孢子存活;培养3d后胚胎诱导则以14％蔗糖浓度为最好;高浓度（17％）蔗糖培养3d后添加低浓度（11％）蔗糖培养液能大大提高胚胎发生能力,比一直在14％蔗糖培养液培养的提高282．4％,比更新培养液培养的提高126．1％。     

Entropy budget of conifer branches

From energy budget data for a branch of ponderosa pine given by Gates, Tibbals and Kreith, entropy fluxes into or out of the branch due to solar radiation, infrared radiation, transpiration and convection are calculated. Net entropy flow into the branch is negative. Assuming that the entropy in the branch is at steady state, the entropy production in the branch of ponderosa pine is calculated and shown to be positive. A positive entropy production indicates that the Second Law of Thermodynamics is certainly valid in the branch. Entropy productions in other conifers, blue spruce and white fir, and in a single pine needle in a horizontal position are also calculated. The entropy production (S_prod) increases linearly with the solar energy absorbed by the plant surface (E_solar); S_prod≈(30.6 E_solar)×10⁻⁴. The ratio (S_prod/E_solar) does not differ between deciduous leaves reported earlier and conifer branches. The theorem of oscillating entropy production proposed earlier holds also for conifer branches and will be of universal nature, applicable to all plant leaves.     

Enthalpy/entropy compensation phenomena in the reduction thermodynamics of electron transport metalloproteins

Compensation phenomena between the enthalpy and entropy changes of the reduction reaction for all classes of electron transport metalloproteins, namely cytochromes, iron-sulfur, and blue copper proteins, are brought to light. This is the first comprehensive report on such effects for biological redox reactions. Following Grunwalds approach for the interpretation of H/S compensation for solution reactions, it is concluded that reduction-induced solvent reorganization effects involving the hydration shell of the molecule dominate the reduction thermodynamics in these species, although they have no net effect on the E° values, owing to exact compensation. Thus the reduction potentials of these species are primarily determined by the selective enthalpic stabilization of one of the two oxidation states due to ligand binding interactions and electrostatics at the metal site and by the entropic effects of reduction-induced changes in protein flexibility.     

一个高频率的活体-离体胚胎发生研究系统

通过对受精后烟草(Nicotiana tabacumL.)胚珠的体外培养,建立了一个简便、实用、高频率的胚胎发生研究系统。采用MS培养基附加6%蔗糖,然后换以2%蔗糖对烟草胚珠进行培养,结果受精后胚珠在体外可以完成正常的胚胎发生并可直接萌发成幼苗。追踪观察表明,合子体外胚胎发生过程中关键发育事件,如合子休眠期间的定向生长、一次不对称分裂的完成、胚柄的形成和解体、胚的分化等过程均可在体外重现。体外培养形成的胚珠及胚胎在形态上与自然状态下形成的胚珠及胚胎几乎没有差异。此体系操作简单,稳定性好,且关键发育事件的时空调控与自然胚胎发育进程相吻合。     

New considerations of the Barclay-Butler rule and the behavior of water dissolved in organic solvents

The Barclay–Butler (B-B) rule, which states that a linear relationship exists between the standard ΔH_vap and ΔS_vap for simple, non-associated liquids and their solutions, has been used to distinguish associated (‘abnormal’) liquids from simple (‘normal’) liquids. The exact character of the B-B plots depends on the standard states chosen for the liquid/solution and vapor. We examine the effects of using number density for both vapor and liquid states for pure liquids, non-aqueous solutions, aqueous solutions and solutions in which water is the solute. The utility of B-B plots to detect solute-induced order is strengthened, and we also find remarkable changes in the modified B-B relationship: (1) the points for small, H-bonded liquids, including water, are pulled below the general B-B line; (2) many solutions containing small, simple solutes have negative entropies of vaporization; and (3) solutions of water in several organic solvents, relevant to studies of proteins and micelles, appear ‘abnormal’.