黑麦1R染色体的显微分离与回收

建立了利用显微操作技术分离植物单个染色体的方法。以黑麦(Secale cereale L.)为材料,以其标准染色体组型图为依据,识别出黑麦含抗病基因的1R染色体。经显微操作,将单条1R染色体放入Ep-pendorf管中。研究表明,用α-溴奈饱和液对细胞进行预处理,可快速鉴别出黑麦1R染色体。采用去壁低渗制片技术,可明显地改善显微分离单染色体的条件。     

PLANT GROWTH AND DEVELOPMENT IN MOLECULAR PERSPECTIVE

• 1 After some false starts in which inactive plant substances were isolated, the isolation and identification of auxin as the growth substance at the meristems and of ethylene as the ripening agent in climacteric fruits represented outstanding achievements.
• 2 In early work, the non-localized origin of auxin at the meristem and its possible transport for coleoptile development were obscured by the superimposition on the results of physiological experiments of the idea of a close parallelism between the plant-growth substances and mammalian hormones. At that time, an absence of chemical instrumentation, suitable for measurement of the tissue levels, compounded the difficulty in interpreting available physiological evidence.
• 3 Member(s) of each of the five groups of naturally occurring plant-growth substances, namely the auxins, cytokinins, gibberellins, ethylene and the growth inhibitors, including abscisic acid, are biologically active at a concentration of 10 μm or less, however, and in this respect they would appear to qualify as candidate phytohormones.
• 4 The sensitivity of plant cells to phytohormones contributes to plant growth and development, and both the variations in sensitivity, for example, of wheat coleoptiles towards growth and the growth of the coleoptiles per se give parallel unimodal relationships with regard to time; the curve representing sensitivity precedes that for growth. A new graphical analysis implies that the growth sensitivity and growth rate functions are mutually interdependent.
• 5 The assumption is made in point 4 that growth substance complexes with receptor protein in growth-sensitive cells, and the concept of receptors would provide explanation for the obvious amplification of effects induced by growth substances.
• 6 Numerous biological situations occur in which the presence of significant amounts of plant hormone controls growth and development. In gravitropism and phototropism, tropistic curvature depends on the difference in physiological concentration of auxin on the two sides of the organ concerned. In infected tobacco plants, the cytokinin to auxin ratios for the tumours determine the kind of development (tumours and shoots, tumours only or tumours plus roots), which takes place.
• 7 Auxin-binding protein has been identified immunologically, and isolated. Work with hormone receptors for gibberellin does not afford unequivocal evidence for more than one primary site of action. Hitherto, no specific receptor protein is known for cytokinins.
• 8 Clear evidence derives, both from structure–activity relationships and from unimodal concentration–response curves, for receptor specificity to auxin action. There is also evidence for a structure–activity relationship in respect of the cytokinin series of compounds.
• 9 From the evidence (points 1–8), there emerges a picture of hormone-induced growth and development of plant cells, which have been made sensitive to hormone through the presence of specific receptor proteins.
• 10 That plant growth and developmental processes involve changes in gene expression would seem to follow from the totipotent nature of meristematic cells, which are capable of specialization in response to phytohormones.
• 11 Auxin regulates de novo synthesis of mRNAs encoding polypeptides essential to the auxin-induced early process of cell elongation. In fact, auxin regulates the concentrations of several authenticated mRNAs and proteins, for example, in elongating soyabean hypocotyl sections.
• 12 Furthermore, two cDNA clones, termed pJCW₁ and pJCW₂ have been isolated with the properties expected of mRNAs involved in the rate-limiting stage of cell elongation. The evidence suggests that the change in relative abundance of the JCW₁ and JCW₂ RNAs is an obligatory auxin-dependent response. Hence, the action of cytokinin in auxin-induced cell elongation would seem to be concerned with the inhibition of rate-limiting proteins, and in fact cytokinin inhibits protein synthesis in excised soyabean hypocotyl.
• 13 Biosystemic experiments on some rapid effects of synthetic auxin growth regulators on mRNA levels in vitro show that there is only partial similarity between those found in pea and soyabean spp. (Leguminosae).
• 14 Two identified sequences, namely TGATAAAAG and GGCAGCATGCA, of two auxin-regulated soyabean genes afford a means for determining whether the auxin-regulation of expression of these genes involves trans-acting regulatory factors.
• 15 The obligatory auxin-induced responses with regard to cell elongation and growth (q.v.) would seem to precede the somewhat mechanical growth properties by which auxin receptive cells secrete H⁺ and lower the pH to yield increased cell-wall plasticity.
• 16 In vertically oriented soyabean seedlings, auxin-regulated RNAs are distributed symmetrically in the elongating region of the hypocotyl, whereas in horizontally oriented seedlings the distribution becomes asymmetrical within a few minutes of horizontal gravitational stimulation. The dynamic expression of auxin-regulated genes is related to the morphogenetic response, initiated by re-distribution of endogenous auxin (point 6).
• 17 In the germination of seeds, the mobilization of food reserves requires hydrolytic enzymes and, in barley grains, gibberellic acid induces de novo biosynthesis of α-amylase and protease. The genetic implications are discussed, and the requirement of dicotyledonous and gymnospermous seeds for the presence of gibberellins is explored.
• 18 In ripening climacteric fruits, ethylene-induced change(s) in gene expression cause de novo biosynthesis of polygalacturonase, which degrades the cell-wall pectin fraction.
• 19 Accordingly, incontestible evidence has been mustered for the proposition that hormone-regulated plant growth and development involves hormone-regulated gene expression.
• 20 As well as the phytohormones, certain environmental factors, such as white light and stress (including anaerobiosis, chilling, heat shock, heavy metal exposure, u.v. light and wounding) have the capacity to regulate gene expression in plants at important stages in growth and development. Discussion at the genetic level focuses on changes produced by:
• 21 The synthesis of phytohormones is significant. For example, as u.v. light-induced regulation of genes produces enzymes for auxin synthesis, it may be responsible in seeds for the endospermal generation of auxins, concerned with the epicotyl/hypocotyl growth in the seedlings.
• 22 Hormones and certain environemental factors (q.v.) initiate some of the numerous stages in plant growth and development, but the regulatory factors are obscure in some other biological situations, such as:
• 23 Utilization of an appropriately re-constituted plant DNA polymerase i in vitro system might enable the type and frequency of misincorporation, produced by plant-growth factors, to be studied. Base-pair substitution changes were produced in strains of crop plant, made resistant to a specific herbicide by genetic engineering (see Hathway, 1989). It is feasible that auxin may behave as a reagent in the chemical sense to effect intramolecular change(s) in some of the sequences concerned, leading to the frame-shift changes observed (see Ainley et al., 1988).

     

黑麦雄性细胞发育过程中细胞器DNA动态的荧光研究

DAPI(4’,6-diamidino-2-phenylindole)是一种DNA特异结合的荧光染料,可以用于在荧光显微镜下观察和检测各种DNA,尤其是细胞内含量甚微的DNA,包括质体DNA和线粒体DNA,其灵敏性和可靠性是被公认的,并得到了越来越多的Southern杂交实验的证明,而且实验操作简便易行。近几年,DAPI荧光技术已在细胞质遗传的研究领域获得了成功的应用。     

斑鰶仔、稚鱼形态发育及异速生长模式研究

运用光学显微镜技术和实验生态学方法, 对斑鰶(Konosirus punctatus)早期形态发育观察、异速生长模式及其生态学意义进行了研究。结果表明: 在水温(21.5±0.5)℃下, 初孵仔鱼全长(3.18±0.52) mm, 斑鰶仔鱼期从孵化出膜到43日龄棱鳞开始出现前, 稚鱼期从44日龄棱鳞出现到55日龄全身覆满鳞片。斑鰶的形态变化和器官分化主要发生在仔鱼期。斑鰶的吻长、躯干长、肠道长、胸鳍长、腹鳍长等重要形态学指标均存在异速生长现象, 其生长拐点依次为 42日龄(TL: 26.41 mm)、24日龄(TL: 15.57 mm)、31日龄(TL: 21.41 mm)、41日龄(TL: 25.47 mm)、42日龄(TL: 26.41 mm)。相对于全长、吻长和胸鳍长在拐点前后由正异速生长变为等速生长, 腹鳍长由正异速生长转为负异速生长, 这为呼吸、摄食和成功逃避捕食者提供有利条件; 而肠道长由负异速生长变为等速生长, 这可能与斑鰶的食性转化有关。综上所述, 为适应复杂多变的生存环境, 斑鰶在早期发育阶段优先发育对生长生存起关键作用的器官, 这对提高仔、稚鱼的存活率具有重要的生态学意义。研究将为今后进一步人工繁育和苗种培育提供理论依据。     

胞松素B对黑麦花粉母细胞发育的影响

采用花药离体培养研究了胞松素B对黑麦花粉母细胞的发育及显微和亚显微结构的影响。细线期和偶线期接种的花药在含有5—40μmol/L胞松素B的White培养基上培养24小时以后,部分花药不能进一步发育,被抑制在偶线期阶段,并且偶线期花药的百分率随胞松素B浓度的增加而增加。在被抑制的偶线期的花药中,多数花药的花粉母细胞被抑制在细胞融合期或细胞融合前时期。电子显微镜观察发现,相邻花粉母细胞间的胞间连丝通道仍然处于开放状态,内部充满细胞质基质和一些细胞器,细胞核停留在胞间连丝通道口附近,通道内部及附近细胞质内的微管系统依然存在。文章讨论了胞松素B对细胞融合的作用。     

LOCOMOTOR PERFORMANCE AT LOW TEMPERATURE AND THE EVOLUTION OF NOCTURNALITY IN GECKOS

Nocturnal geckos are active at body temperatures 10–35°C below the thermal optima for maximum rate of aerobic metabolism of diurnal lizards. Therefore, given ancestral (diurnal) lizard physiology, nocturnality causes a substantial thermal handicap in locomotor performance. In prior studies, we hypothesized that a low minimum cost of locomotion (C_min) in geckos was an adaptation that increased locomotor endurance capacity at low, nocturnal temperatures. However, C_min is only part of an integrated system that, in conjunction with the maximum rate of oxygen consumption, sets the maximum speed that can be sustained aerobically (termed the maximum aerobic speed or MAS). We conducted the first phylogenetic analysis of MAS and lizards and found that the greatest changes in MAS, C_min and (at activity temperatures) in the evolutionary history of lizards all coincided with the evolution of nocturnality in geckos. Geckos active at 15–25°C did not become optimized for nocturnal temperatures, or fully offset the thermal effects of nocturnality by evolving maximal rates of oxygen consumption comparable to diurnal lizards active at 35°C. Geckos did evolve MAS twice that of diurnal lizards running at low temperatures by evolving a remarkably low C_min. Allometric analysis and phylogenetically independent contrasts of , C_min, and MAS indicate a 72% evolutionary decrease in , (at activity temperatures) and a 50% evolutionary decrease in C_min concordant with the evolution of nocturnality in geckos. Experimental measurements show that decreased C_min in six species of gecko increased MAS by 50–120% compared to diurnal lizards at low temperatures. Thus, geckos sufficiently overcame the near paralyzing effects of nocturnal temperatures, but only offset about 50% of the decrease in MAS resulting from the low maximum rate of oxygen consumption. Although the nocturnal environment remains severely suboptimal, the evolution of a low cost of locomotion in the ancestor of geckos was highly adaptive for nocturnality. We also present a generalized approach to ecophysiological evolution that integrates phylogeny with the causal relationships among environment, physiology, and performance capacity. With respect to a clade, two hypotheses are central to our integrative approach: (1) a change of an environmental variable (e.g., temperature) causes a performance handicap; and (2) evolution of a physiological variable (e.g., minimum cost of locomotion [C_min]) increases performance in the derived environment. To test the hypothesis that evolution of a physiological variable is adaptive in nature, we suggest determining if individuals in nature perform at levels exceeding the performance capacity of their hypothetical ancestors and if this additional performance capacity is due to the evolution of the physiological variable in question.     

鸭绿江唇仔、稚鱼形态发育与早期生长

通过观察、拍照和测量的方法对鸭绿江唇(Hemibarbus labeo)仔、稚鱼的形态发育和早期生长进行了研究。结果表明:在19.6—25.8℃的试验条件下,唇初孵化仔鱼全长为(7.92±0.29)mm,2日龄头部两侧出现感觉芽;3日龄鳔一室原基形成,5日龄红色的脾出现,且仔鱼开口;7日龄卵黄囊吸收完毕,9日龄脊索末端开始向上弯曲;10日龄鳔二室形成,14日龄脊索弯曲完成,尾鳍边缘开始内凹;32日龄鳞片开始出现在鳃盖后缘的体表,同时各鳍发育完全,个体发育进入稚鱼期,43日龄全身被鳞,个体发育进入幼鱼期。根据卵黄囊、脊索和鳞片的变化,唇胚后发育可细分为卵黄囊期(0—6日龄)、弯曲前期(7—9日龄)、弯曲期(10—14日龄)、弯曲后期(15—32日龄)和稚鱼期(33—43日龄)。试验期间,全长和体质量的特定生长率分别为3.32%和12.16%;卵黄囊体积(V)与日龄(d)的关系为V=0.0048d3–0.0309d2–0.1240d+0.8453(R2=0.8933);全长(LT)、体质量(W)与日龄均为指数函数关系,相关方程分别为:LT=8.3821e0.0329d(R2=0.9586),W=0.0048e0.0969d(R2=0.9463);头长(LH)、体高(HB)的生长方程分别为:LH=–6E–05d3+0.002d2+0.1733d+0.7862(R2=0.9577),HB=–5E–05d3+0.0039d2+0.017d+0.9389(R2=0.9621)。     

GROWTH, DEVELOPMENT AND RESPIRATION IN THE OVULES OF ZEPHYRANTHES LANCASTERI AT DIFFERENT STAGES OF MATURATION

Changes in the rate of respiration and activity of succinicdehydrogenase in the ovules, embryo and endosperm have beeninvestigated at different stages of seed development in Z. lancasteri.An attempt has been made to find any possible relation betweenphysiological changes and the growth pattern of ovule. The fertilizedovules mature into seeds in 16–19 days from the time ofpollination. The respiratory course and the growth of ovulesfollow identical trends. The curve for oxygen uptake is characterizedby at least two peaks; the first on the sixth or seventh dayis related to the laying down of walls in the coenocytic micropylarchamber of the endosperm and the second on the 11th day precedesthe elongation of cotyledon. In excised endosperm the activityof succinic dehydrogenase is highest during its transformationfrom freenuclear to cellular state, while in the embryo it isso after the attainment of mature size. ¹Present address: AEC Plant Research Laboratory, Michigan StateUniversity, East Lansing, Mich., U.S.A.     

CHANGES IN WATER ECONOMY IN RELATION TO ANATOMICAL AND MORPHOLOGICAL CHARACTERISTICS DURING THALLUS DEVELOPMENT INPARMELIA ACETABULUM

The influence on uptake and water loss of the structural changes experienced by Parmelia acetabulum during thallus development were investigated. Small specimens were characterized by flat lobes and a thin thallus and cortex. Large specimens appeared strongly rugose, imbricate and irregularly folded, and had a significantly thicker cortex and medulla than small thalli. Maximum water storage capacity did not differ between large and small thalli, although water retention was much higher in large thalli, presumably due to the interaction of structural characteristics and a higher boundary layer resistance. This translated into a longer duration of the period of thallus hydration in large thalli compared to small thalli. Incubation of thalli in water-vapour-saturated atmospheres induced full recovery of photosynthetic electron transport to the values before desiccation in small thalli but only induced a partial recovery in large thalli. The close correlation between photosynthetic electron transport and net photosynthesis during desiccation found in this species suggested that carbon-fixation activity could be regained to a larger extent by incubation of thalli in water vapour in small compared to large thalli. The higher ability for water vapour uptake of small thalli might allow them to efficiently use small amounts of intermittently available water or periods of high relative humidity. The significance of this differential ability to utilize water is discussed with regard to the known ecological preferences of the species.     

低温对3种作物幼苗生长的影响及与根系内同工酶变化的关系

０－４℃低温处理黄豆、绿豆、红小豆３种作物幼苗,它们的生长均明显受抑制,其中红小豆和绿豆从处理的第一天起生长就完全受抑;黄豆幼苗生长虽也受抑,但仍有缓慢生长现象。比较３种作物根系中ＰＯＤ、ＣＯＤ、ＡＴＰａｓｅ同工酶,其中ＣＯＤ未观察到有明显变化,但ＰＯＤ和ＡＴＰａｓｅ同工酶变化明显,０－４℃低温下３种幼苗生长受抑与根系及同工酶的变化呈一定的相关性。     

EFFECT OF GRAZING-ASSOCIATED INFOCHEMICALS ON GROWTH AND MORPHOLOGICAL DEVELOPMENT IN SCENEDESMUS ACUTUS (CHLOROPHYCEAE)

Populations of the phenotypically plastic alga Scenedesmus acutus Meyen were cultured in standard medium or in medium with filtered water from a Daphnia culture to examine the expression of ecomorphs in both water types. A rapid formation of four- and eight-celled coenobia was observed in the presence of Daphnia water, but not in standard medium. Moreover, cell dimensions were increased in the Daphnia water containing medium. Population growth rates were comparable in both water types; however, the carrying capacity appeared significantly lower in Daphnia water. Daphnia needed to feed on digestible food to produce the colony-inducing chemicals; medium from starved animals and Daphnia fed polystyrene beads appeared inactive. Neither suspensions of homogenate of Scenedesmus and Cryptomonas nor auxins affected colony formation or growth rate in S. acutus. The colony-inducing infochemicals are probably not constituents of the algae themselves; however, modification of algal constituents in the digestive system of daphniids may be involved.     

几种转基因植物体细胞克隆变异的多样性研究

分析了杨树、水稻和甘蔗转基因植株体细胞克隆的表型变异和基因组DNA多态性。探讨了以下问题:转基因植株体细胞克隆的1)表型多样性, 2)基因组DNA多样性, 3)二者的相关性, 4)表型变异和DNA变异的可遗传特性, 5)产生的可能原因,以及6)在农业生产上的应用。     

EXCYSTMENT AND GROWTH OF CHRYSOPHYTES AND DINOFLAGELLATES AT LOW TEMPERATURES AND HIGH SALINITIES IN ANTARCTIC SEA-ICE1

Extreme environmental conditions have been thought to limit algal growth in the upper sea-ice. In McMurdo Sound, Antarctica, chrysophyte statocysts (stomatocysts) and dinoflagellate hypnozygotes (resting cysts) overwinter in first- and second-year land-fast sea-ice exposed to temperatures of -20° C or lower. In early November, when temperatures in the upper ice are < ?8°C and brine salinities are >126 psu, dinoflagellate cysts activate and shortly thereafter excyst. During early November, chrysophyte statocysts also begin to excyst. Net daily primary production occurs in the sea-ice brine at temperatures as low as ?7.1° C, at brine salinities as high as 129 psu, and at average photon flux densities as low as 5 μmol photons.m^?2.s^?1. Dinoflagellate densities were >10⁶ vegetative cells.L^?1 of ice while temperatures in the upper ice were between ?6.8 and ?5.8° C and brine salinities were ～100 psu. Chrysophyte densities reached >10⁶.L^?1 of ice by early December. High densities of physiologically active clyo- and halotolerant algae can occur in the upper land-fast sea-ice under extreme conditions of temperature and salinity.     

CYTOGENETIC AND EVOLUTIONARY STUDIES IN SECALE. I. SOME NEW DATA ON THE ANCESTRY OF S. CEREALE

Khush , G. S., and G. L. Stebbins . (U. California, Davis.) Cytogenetic and evolutionary studies in Secale. I. Some new data on the ancestry of S. cereale. Amer. Jour. Bot. 48(8): 723–730. Illus. 1961.—Cultivated rye, Secale cereale, was crossed with all 4 wild species of the genus. It crosses readily with S. montanum, S. africanum, and S. vavilovii, but crossability of S. cereale and S. silvestre is extremely low. Meiosis in the hybrid S. cereale × silvestre is characterized by high frequency of univalents at metaphase I, reduced chiasma frequency at metaphase I, high frequency of PMC's with unequal separations and laggards at anaphase I and II, high frequency of microspores with micronuclei, and extremely low pollen fertility. These abnormalities occurred less frequently in other hybrids, and consequently the pollen fertility is fairly high: 19.1% in the hybrid S. cereale × vavilovii and 31.3% and 31.8%, respectively, in the hybrids S. cereale × montanum and S. cereale × africanum. An interesting cytogenetic feature of all these hybrids, however, was the formation of a translocation configuration of 6 chromosomes at metaphase I of meiosis. In the hybrid, S. cereale × silvestre, a translocation configuration of 8 chromosomes was observed in a few cells. It is evident, therefore, that the genome of S. cereale differs from the genomes of wild species by 2 translocations. Another small translocation may differentiate S. cereale and S. silvestre, in addition. Thus, on the basis of chromosome arrangements, no particular wild species is most likely to be ancestral to S. cereale. Similarly, Stutz's hypothesis of hybrid origin of S. cereale seems highly improbable. After considering ecological preferences, breeding habits, geographical distribution, morphological and cytological affinities of wild species and cultivated rye, it is concluded that S. cereale evolved from S. montanum as a result of progressive cytological and morphological differentiation and that this differentiation was facilitated, probably, by adaptive superiority of translocation heterozygotes and rearrangement homozygotes.     

芜湖市284名小学生生长发育的追踪研究

本文报道了1992年10月— 1997年10月对芜湖市284名 6—11岁汉族小学生生长发育的追踪调查结果。调查指标为身高、体重、胸围、脉搏和肺活量。对形态发育指数进行了分析。分析了男女间的差异。并与汉族 1985和1986年均值和日本人数据进行了比较。对当前儿童少年生长发育加速趋势也进行了讨论。