豇豆几丁质酶部分酶学特性的研究

该文测定了纯化的豇豆几丁质酶部分酶学特性。结果表明,该酶在pH5-8,温度低于60℃的范围内稳定性较好,酶活力最适pH为65,最适温度为50℃。10mmol/L浓度的Hg2 、Mn2 、Mg2 、Co2 等金属离子对酶活力有一定抑制作用,其中Hg2 离子抑制率最高(6883%)。Km(胶状几丁质)值为1662mg/ml;以SDS-PAGE电泳和SephadexG-100柱层析两种方法分别测得分子量为34kD、325kD;IEF电泳测得等电点为83。     

CHANGES IN THE AMOUNT OF GIBBERELLIN-LIKE SUBSTANCES IN THE SEEDLING OF PHARBITIS NIL WITH SPECIAL REFERENCE TO EXPANSION OF COTYLEDON

Two gibberellin-like substances were separated chromatographicallyfrom the ethanol-extract of germinating cotyledons of Pharbitisnil. In the dark-grown seedling, these substances in the cotyledonincreased in amount gradually with the slow increase in freshweight and area of the tissue, and attained, 4 days after sowing,a maximum level of 0.03 µg gibberellin A₃ equivalent pera couple of cotyledon; in the light-grown seedling, they increasedrapidly with the rapid increase in the fresh weight and area,and attained a maximum content of 0.07 µg gibberellinA₃ equivalent per cotyledon on the 6th day. When the etiolatedseedling was exposed to light, the amount of the gibberellin-likesubstances in the cotyledon increased in parallel with openingof the hypccotyl hook and expansion of the cotyledon. The openingof the hook and increase of the substances occurred in red lightas well as in far-red. Relatively small amounts of the gibberellin-like substanceswere also contained in the germinating hypocotyl and root. The growth of cotyledonary disks was promoted by gibberellinA₃ and the gibberellin-like substances from the expanding cotyledon. The dwarf rice seedling and dwarfs 1, 3 and 5 of maize respondedto the gibberellin-like substances, but dwarf Pharbitis didnot. (Received August 20, 1963; )     

A METABOLIC PATHWAY OF ISOCITRIC ACID IN COTYLEDONS OF A BEAN, VIGNA SESQUIPEDALIS

1. It has been established that the absence of isocitric dehydrogenaseactivity in cotyledons of Vigna sesquipedalisin the germinationstage is due to the lack of endogenous TPN. It is unlikely thatthe TCA cycle in the cotyledon is operative.
2. The activitiesof enzymes of the glyoxylate cycle, a modifiedTCA cycle, weremeasured through the germination stage. Theiractivities wereconsiderably higher in the cotyledon tissuethan in the hypocotyl.A dominant metabolic pathway of isocitricacid in the cotyledonmay be the glyoxylate cycle.
3. DPN kinase which produces TPNfrom DPN, ATP and Mg⁺⁺ was localizedin the supernatant portionof cell components in the cotyledon.Its activity was low. DPNkinase serves as a control factorfor the cotyledon metabolism.

(Received April 17, 1961; )     

THE TRANSPORT AND FUNCTION OF SILICON IN PLANTS

A number of lines of evidence (M_r, number of -OH groups, measured fluxes at inner mitochondrial membranes) suggest the intrinsic P_Si(OH)₄ of about 10^-10 m s^-1 in the plant cell plasmalemma. While relatively low, such a P_Si(OH)₄ could maintain the intracellular concentration of Si(OH)₄ equal to that in the medium for a phytoplankton cell of 5 μm radius growing with a generation time of 24 h. Such passive entry could not account for SiO, precipitation such as is required for scale (Chrysophyceae) or wall (Bacillariophyceae) production in terms of either the generation of a super-saturated solution or the quantity of SiO₂ required; active transport occurs at the plasmalemma (and possibly at an internal membrane) of such cells. The energy required for silicification, even in a diatom with an Si/C ratio of 0.25, is only some 2% of the total energy (as NADPH and ATP) needed for growth; the energy cost of leakage of Si(OH)₄ due to the intrinsic permeability of lipid bilayers to Si(OH)₄ is never more than 10% of the cost of silicification. In vascular land plants the entry of Si from the soil into the xylem can involve a flux ratio (mol Si/m³ water) that is less than (e.g. Leguminoseae) equal to (e.g. many Gramineae) or greater than (e.g. Oryza, Equisetum) the concentration (mol m^-3) in the bathing solution. Even the low influx of the Leguminoseae cannot be accounted for by the ‘lipid solution’ value of PS(OH)₄, but requires entry coupled (phenomenologically) to water influx with a reflexion coefficient of about 0.9. The situation in most Gramineae is described by such a coupling with a reflexion coefficient near O, while the accumulation of Si (relative to water) in Oryza and Equisetum involves an apparent reflexion coefficient which is negative, i.e. an active transport system stoichiometrically related to water flux. Even in Leguminoseae with a transpiration-stream concentration of Si(OH)₄ of only 20 mmol m^-3 (cf. the soil solution at 200 mmol m^-3), the fact that only I % of the water in the xylem is retained in the plant means that Si(OH)₄ at transpirational termini approaches saturation; super-saturation, and precipitation of SiO, occurs in Gramineae and Equisetum. SiO₂ precipitation occurs mainly near transpirational termini but can also occur in the xylem vessels and endodermis of roots, for example. Si(OH)₂ mobility in the phloem seems to be very restricted. The energy costs of SiO₂ relative to organic compounds as structural and defensive materials are in the ratio of 1:10-1:20 (on the basis of weight of material). The relative rarity of SiO₂ as a structural material is discussed in the context of the evolution of Si(OH)₄-transport mechanisms.     

长豇豆胚和胚乳的发育及营养物质积累

长豇豆(Vigna sesquipedalis (L.)Fruwirth)开花前7—10小时传粉,开花后8—10小时完成双受精。合子期珠孔端及合点部位胚囊的周界壁有壁内突。胚发育属柳叶菜型。胚柄的基部细胞及基部区域外层细胞的外切向壁发生壁内突。成熟胚中胚柄宿存。开花后9—16天为子叶细胞中淀粉积累期,开花后12—18天为蛋白质积累期。胚乳发育为核型,珠孔端胚乳细胞化,合点端保持游离核状态。胚乳外层细胞为传递型细胞,珠孔端的胚乳细胞形成折叠细胞群,亦有壁内突。心形胚期胚乳开始退化解体,成熟胚期胚乳完全消失。     

从顶枝学说、中柱学说和子叶节区学说看维管植物的形态演化和起源

作者对当前植物形态学中与维管植物的形态演化和起源有着十分密切关系的顶枝学说,中柱学说与子叶节区学说进行了全面研究。并结合半个多世纪以来国际上著名的植物系统学家的维管植物分类系统,反复进行了比较和研究,对其中认为不妥之处提出了我们的见解,具体反映在文后的“维管植物系统的系统发育图”中。     

EFFECT OF VARIOUS ANIONS ON THE TRANSPORT OF STRONTIUM WITHIN PLANTS

With a view to finding a means of reducing contamination offoods by radiostrontium, the inhibiting effects of various anionson the transport of strontium in plants are investigated. Pea and bean plants were pretreated with silicate, phosphateand nitrate ions, and the distribution of strontium in variousparts of the plants was examined.

1. In the case of pretreatment with silicate or phosphate ions,strontium absorption by the plant was decreased even if theseanions were absent in the culture solution at the time of applicationof ⁸⁹Sr.
2. The absorption of strontium by the plants pretreatedwith nitrateions was similar to that of the controls.
3. Strontiumabsorbed by the plants pretreated with silicate orphosphatewas found to be accumulated in the roots and its quantitytransportedto the aboveground parts was remarkably small; especiallyinthe case of application of silicate, no measurable amountofstrontium was transported to the upper parts of the plant.
4. Inthe control and nitrate-pretreated plants, strontium absorbedin the roots was readily transported to the aboveground parts.

(Received March 15, 1965; )     

分离MEF和ES细胞的差速贴壁法研究(简报)

胚胎干细胞的分化控制是胚胎干细胞研究的一个重要方面。由于常规的拟胚体诱导途径是在形成拟胚体后才开始进行诱导分化,受多种胚层的共同作用使得我们无法简便探索诱导分化的机制。而且用这种方法进行的诱导分化试验的结果检测比     

TRANSPORT OF LYSINE FROM CEREBROSPINAL FLUID OF THE CAT

—The clearance from cerebrospinal fluid of l-[¹⁴C]lysine and l-[³H]arginine was measured during ventriculo-cisternal perfusions of anaesthetized cats. Increasing in the perfusate the concentration of unlabelled l-lysine produced a gradual reduction in clearance of the labelled amino acids without altering the uptake of l-[¹⁴C]lysine by the choroid plexus. Net transport of l-lysine out of cerebrospinal fluid occurred by saturable and non-saturable components. The saturable component satisfied Michaelis-Menton kinetics, while the behaviour of the non-saturable component was consistent with diffusion. A V_max of 0·017 μmol/min and an affinity constant (k_t) of 0·83 mm were estimated. The clearance of l-lysine was unaffected by the addition to the perfusate of high concentrations of selected neutral amino acids, but was stimulated by the presence of l-cystine. Conversely, a high concentration of l-lysine did not affect the clearance of glycine or cycloleucine. The dibasic amino acids appear to be removed from cerebrospinal fluid by a relatively specific, mediated transport system which may serve to regulate their concentrations in the cerebrospinal fluid.     

二价金属离子在分离大豆种子尿囊素酶中的作用

大豆 (Glycine max L.cv.Keyu 10 )种子和叶片提取液中的尿囊素酶 (ALNase)是热稳定的 ,但在Ca2 、Mg2 或 Mn2 存在的条件下对热有不同的反应。 75℃热处理 5 min,种子提取液中的酶除 Mg2 尚存有 1/ 3酶活性外 ,其余全部丧失 ,56%以上的蛋白质变性 ;叶片提取液中的酶除 Mn2 使活性下降 36%外其余仍然稳定 ,热变性蛋白也不因 Ca2 、Mg2 和 Mn2 的存在有明显增加。在室温下二价金属离子可以清除大豆种子提取液中 50 %以上非酶蛋白 ,但不影响酶活性。二价金属离子这种作用和其浓度无关 ,增加浓度反而有减弱的趋势 ,也不受 Na Cl的影响。两种 ALNase提取液对不同的难溶性钙盐也有不同的反应 ,种子提取液经 5% Ca SO4 处理后非酶蛋白减少近 50 % ,酶活性受影响不大 ;叶片提取液对Ca3 (PO4 ) 2 敏感 ,经处理后酶活性损失 50 %左右 ,蛋白损失近 70 %。 Mn2 对种子提取液中 ALNase有激活作用 ,但这种激活作用随着酶的纯化而消失。乙二胺四乙酸钠 (EDTA)对两种提取液中 ALNase活性没有影响 ,但外加二价金属离子浓度接近 DETA浓度时酶活性很快丢失     

中国西北地区菊科新植物

多年生草本。茎直立,圆柱形,密被白色向上贴生的长毛,微左右曲折,先端分枝。基生叶和茎下部叶未见,茎中部和上部叶卵形,宽椭圆形或倒卵状披针形,长2-8厘米,宽1-4厘米,先端钝尖或近圆形,基部渐狭,缘有不明显的波状圆齿,齿端有脐服体,表面绿色,被白色短硬毛,背面被灰白色浓密的贴生长毛,叶脉在背面凸起,有3-4对侧脉,叶柄短或近无,有狭翅。     

绿豆幼苗中细胞色素氧化酶与酯酶同工酶的调控研究

以转录抑制剂放线菌素Ｄ和转译抑制剂环己亚胺为工具的实验表明,４－氯苯氧乙酸（ＣＰＡ）与２,４－Ｄ促进绿豆幼苗中的细胞色素氧化酶同工酶的活性,是由于刺激了种子中预存ｍＲＮＡ转译的结果。此外,发现环己亚胺对酯酶同工酶的活性有非常明显的刺激作用,其原因尚待进一步研究。