小球藻RubisCO的纯化及其在异养向自养转变过程中的含量变化

经硫酸铵分部沉淀、ＳｅｐｈａｃｒｙｌＳ－３００和ＤＥＡＥ－纤维素柱层析纯化了小球藻ＲｕｂｉｓＣＯ,得率为１５％,比活力达１．２３２μｍｏｌＣＯ２ｍｓ－１ｍｉｎ－１,分子量是５００ｋＤ,它和菠菜叶片ＲｕｂｉｓＣＯ在分子量、亚基组成和免疫特性等方面相似,反映ＲｕｂｉｓＣＯ在高等和低等植物中有较高的同源性。自养小球藻ＲｕｂｉｓＣＯ占细胞可溶性蛋白质的２４％。而异养转变后的小球藻细胞内不含ＲｕｂｉｓＣＯ。异养小球藻向自养生长转变过程中,２０ｈ后细胞内叶绿素含量逐渐增加,２４ｈ时细胞内出现ＲｕｂｉｓＣＯ,２４ｈ后大量增加,至４１ｈ时含量达最高峰;标志着小球藻细胞光合作用能力的恢复和加强。     

精子发生过程中基因表达转录水平的调控

哺乳动物精子发生于睾丸的生精小管, 是一个高度复杂的细胞分裂和分化过程, 涉及到错综复杂的基因表达调控过程, 包括转录和转录后水平的调控, 其中任何一个环节出错都可能导致雄性不育。因此, 揭示精子发生过程中的分子调控机理, 对发现新的男性避孕方法及治疗不育症有重要意义。文章重点综述了近年有关雄激素及其受体、雌激素及其受体、转录因子和染色质相关因子在精子发生转录水平调控的研究进展。     

小球藻的异养培养及应用前景

介绍了小球藻异养培养的营养需求,条件控制以及应用前景。     

竞争性内源RNA在转录后水平调控基因表达

竞争性内源RNA(competing endogenous RNA,ce RNA)假说提出了一种RNA在转录后水平调控基因表达的机制,即信使RNA(message RNA,m RNA)、长链非编码RNA(long non-coding RNA,lnc RNA)、假基因(pseudogene)转录物及环状RNA(circular RNA,circ RNA)通过竞争结合相同的微小RNA(micro RNA,mi RNA)来影响靶基因RNA的稳定性或翻译活性,实现转录后水平的基因表达调节。这一全新的基因表达调控机制目前已在肌肉的分化、胚胎干细胞的分化、中脑的发育及癌症的转移等多个研究领域被发现,并且被证实参与多个生物学过程的调控。ce RNA这种以mi RNA为媒介实现RNA与RNA相互调控的机制,使得编码基因和非编码基因在全转录组范围内形成了一个庞大而精细的调控网络,增加了基因调控网络的复杂性。文章就ce RNA的分子类型、ce RNA机制所涉及的生物学功能、影响ce RNA机制的重要因素及ce RNA调控网络预测这几个方面进行综述。     

均匀设计法优化蛋白核小球藻的异养培养基

[目的]通过优化培养基提高异养蛋白核小球藻CP9的生物量产率、蛋白质以及叶绿素含量。[方法]采用5因素8水平的均匀设计法优化小球藻异养培养基的配方,以葡萄糖、KNO_(3)、MgSO_(4)·7H_(2)O以及Fe-EDTA和CaCl_(2)母液为自变量,分析对小球藻生长、蛋白质含量和叶绿素含量的影响,来确定培养基自变量因素的最佳使用浓度。[结果]得到最佳培养基配方为:葡萄糖73.21 g/L、KNO_(3)6.25 g/L、MgSO_(4)·7H_(2)O 0.79 g/L、Fe-EDTA母液13.01 mL/L、CaCl_(2)母液4.80 mL/L。经培养基优化后将蛋白核小球藻CP9的最高细胞密度、蛋白质含量和叶绿素含量分别从11.08 g/L、43.3%和39.42 mg/g提升至15.08 g/L、60.0%和45.06 mg/g。[结论]通过正交优化蛋白核小球藻的异养培养基,将生物量提高了36%,同时藻细胞含有更高的蛋白质(60.0%)和叶绿素含量(45.06 mg/g),可为开发动物饲料或人类食品蛋白质。     

谷氨酸对异养培养小球藻生长的影响

在不添加其他氮源的小球藻异养培养基中,谷氨酸可促进小球藻的生长,但基本不增加叶绿素的合成;在以铵盐为氮源时,谷氨酸可明显促进小球藻对铵盐的利用,促进小球藻生物量增加和叶绿素合成;在以硝酸盐为氮源时,谷氨酸可增加小球藻的生物量,对叶绿素含量无明显影响。     

转兔防御素基因小球藻异养培养的培养基优化研究

在氮源种类筛选的基础上,采用Plackett-Burman实验设计并结合单因素实验对转兔防御素基因小球藻异养培养的培养基进行了优化。实验结果表明,采用优化后的Knop异养培养基在250mL摇瓶中进行异养培养,藻细胞密度从优化前的1.5g/L提高到优化后的5.11g/L;摇瓶和5L生物反应器异养培养表明,Knop异养培养基中藻细胞浓度分别为优化前培养基的3.39倍和3.17倍,而兔防御素(NP-1)表达能力基本不变。     

以异养细胞作为种子的椭圆小球藻产油脂光自养培养优化

异养细胞种子/光自养培养方法是一种可异养培养的能源微藻培养的有效方法,但已有文献尚未从工艺优化角度考察其发展潜力。为了获得较高细胞密度的用于光自养培养的种子和提高光自养培养的细胞密度与油脂产率,对异养细胞种子/光自养培养的培养基和培养条件进行了优化。结果表明,采用优化后的培养基,椭圆小球藻在摇瓶中异养培养的最高藻细胞密度可达11.04 g/L,比在初始培养基条件下提高了28.0%,在5 L发酵罐中异养培养的藻细胞密度达到73.89 g/L;在2 L柱式光生物反应器中光自养培养的藻细胞密度、油脂含量和油脂产率分别达1.62 g/L、36.34%和6.1 mg/(L·h),油脂成分主要为含C16-C18碳链的脂肪酸,是制备生物柴油的理想原料。经过优化,异养细胞种子/光自养培养这一方法能够显著地提高椭圆小球藻产油脂的能力,这进一步表明异养细胞种子/光自养培养方法有望成为可异养的能源微藻的高效培养方式。     

进化与未进化小球藻响应苯酚的转录组学分析

苯酚是工业废水中典型的环境污染物。小球藻(Chlorella sp.)由于其生长快、抗逆性强,可以有效利用废水中的酚类化合物,是最有潜力的含酚废水处理藻株。但是高浓度苯酚产生的氧化压力会造成小球藻细胞的氧化损伤。通过实验室适应性进化已经得到了可以耐受500mg/L苯酚的小球藻藻株(L5)。通过无参比较转录组学数据,在基因组尺度上考察了原始小球藻(L3)和进化后小球藻对高浓度苯酚的响应差异。无参比较转录组学结果表明,进化后小球藻能够耐受并降解高浓度苯酚是多个代谢途径整体调控的结果。相比于原始小球藻,进化后小球藻在500mg/L苯酚浓度下对苯酚氧化胁迫的响应增强,主要体现在细胞信号转导、ABC转运蛋白、热休克蛋白、氮代谢和三羧酸循环(TCA)等相关的转录水平明显上调。进化后小球藻通过这些响应降低高浓度苯酚产生的氧化压力。     

喜树原形成层到形成层转化的研究

观察了枣树茎中原形成层到形成层的转化过程。距茎端0．5mm处,节间开始伸长之前,横切面上4—5个原形成束及束间的分生组织组成原形成层环。径向切面观,原形成层环呈现出较均一的结构。随着节间开始伸长,由于原形成层细胞发生假横向分裂,出现了长短两类细胞,长细胞多数端壁倾斜,短细胞多数端壁平截。以后,长细胞发育为纺缍状原始细胞,短细胞发育为射线原始细胞,部分射线原始细胞可以伸长井侵入生长而转化为纺缍状原始细胞。在节间伸长将停止时,此种转化基本完成。喜树为非叠生形成层,纺缍状原始细胞和射线原始细胞都有多核现象发生。     

瓦氏雅罗鱼生殖洄游过程中离子调节相关生理变化研究

为了解达里湖瓦氏雅罗鱼(Leuciscus waleckii)生殖洄游过程中血清离子调节相关生理变化, 对比了达里湖和贡格尔河瓦氏雅罗鱼血清离子(Na+、K+、Cl?、Ca2+和Mg2+)水平, 鳃、肠和肾组织Na+/K+-ATPase和鳃Ca2+/Mg2+-ATPase活性、血清催乳素(PRL)、生长激素(GH)和类胰岛素生长因子-1(IGF-1)水平及鳃组织结构差异; 并利用实验生态学方法, 研究达里湖中瓦氏雅罗鱼转入贡格尔河水24h后上述生理参数的响应。研究结果显示, 与达里湖未洄游的瓦氏雅罗鱼相比, 洄游到贡格尔河后其血清Na+含量显著降低(P<0.05), Cl?含量显著升高(P<0.05), 肾脏和肠组织中Na+/K+-ATPase活性显著升高(P<0.05), 而鳃组织中Na+/K+-ATPase活性无显著变化; 血清K+、Ca2+、Mg2+水平和GH、IGF-1、PRL含量无显著变化。将达里湖瓦氏雅罗鱼转入河水中24h后, 其血清Cl?含量显著升高(P<0.05)、K+含量显著降低(P<0.05), 且在鳃、肠和肾组织中Na+/K+-ATPase及鳃Ca2+/Mg2+-ATPase活性均显著升高(P<0.05), 血清PRL和IGF-1水平显著升高(P<0.05); 比较湖中和河中瓦氏雅罗鱼鳃组织形态结构, 显示湖中瓦氏雅罗鱼鳃基底膜分布着大量黏液细胞, 洄游到河水中后黏液细胞数量明显减少, 鳃基底膜上氯细胞体积增大而数量未见明显变化。本研究结果表明: 瓦氏雅罗鱼从达里湖洄游到贡格尔河后通过提高血清PRL和IGF-1水平, 进而介导鳃、肠和肾组织中Na+/K+-ATPase活性增加, 从而维持鱼体较高或稳定的血清离子水平。     

THE PHYSIOLOGICAL TRANSITION FROM FASTING TO FEEDING IN WEANED ELEPHANT SEAL PUPS

We studied energetics and food utilization in young elephant seals as they were first introduced to solid food following their long post-weaning fast. Using radioactive tracer techniques, we monitored changes in body composition, protein metabolism, and metabolic rate during fasting and initial feeding. In fasting animals, fat stores supplied nearly all energetic requirements. In feeding animals, 49% of protein ingested was retained as body tissue, allowing protein mass to increase. Body fat was lost at rates comparable to rates in fasting animals and continued to fuel the bulk of metabolism. Weight loss was arrested when animals consumed 786 g/d, or 40 kcal/kg^0.75/d, which was far less than their metabolic rates (63–206 kcal/kg 0.75 /d). Surprisingly, the young seals were able to maintain weight and store protein while energy intake was below metabolic needs. This was possible because animals gained weight as water; they retained wellhydrated proteinaceous tissue while losing poorly-hydrated adipose tissue.     

全球变化下植物的碳氮关系及其环境调节研究进展——从分子到生态系统

在全球变化条件下,温度的升高和降水格局的变化,导致淡水资源更加匮乏。环境因子胁迫,如干旱和高温等,它们单独或联合的作用将导致作物大幅度减产,引发自然生态系统退化。植物的碳氮代谢及其分配相互联系、不可分割,其生物过程及外界环境调节共同决定着植物的净生产力和营养水平。该文试图从分子、组织、器官、个体和生态系统等层面上,就植物的碳氮关系及其环境调节(温度、水分和CO₂浓度等)进行综述,并提出了进一步展开相关研究应重点关注的几个方面。     

QUANTITATIVE STUDY OF NUCLEIC ACIDS AND PROTEINS IN THE SHOOT APEX OF SINAPIS ALBA DURING TRANSITION FROM THE VEGETATIVE TO THE REPRODUCTIVE CONDITION

Quantitative changes in DNA, histone, RNA, and total protein have been measured in meristematic cells during floral evocation.² A single 22-hr, long-day exposure induced two-month-old vegetative plants of Sinapis alba to flower. Periodic collections of shoot apices were made and stained with Schiff's reagent (DNA), azur B (RNA), alkaline fast green (histone), and naphthol yellow S (total protein). The two-wavelength method was used for DNA and histone measurements and the one-wavelength, two-area procedure was chosen for RNA and total protein determinations. The DNA and histone amounts per cell decreased to a minimum value 34 hr after treatment, and most of the nuclei shifted from 4C to 2C values. DNA and histone quantities paralleled each other from 34–46 hr, after which time the histone values continued to increase and the DNA values decreased. The RNA values increased rapidly after treatment as did the total protein quantities, after a slight decrease at 34 hr concurrent with the 4C to 2C cell population shift. The significance of these events is discussed in relation to the changes which were previously described in the shoot apex of Sinapis in transition to flowering.     

THE RATIO OF CALCAREOUS AND ORGANIC SHELL COMPONENTS OF FRESHWATER SPHAERIID CLAMS IN RELATION TO WATER HARDNESS AND TROPHIC CONDITIONS

Shells from 14 populations of sphaeriid clams including Sphaeriumstriatinum, S. simile, Pisidium walkeri, Musculim partumeiumand M. iransversum were analyzed for organic carbon (µgCmg^–1 shell), nitrogen (µg,N mg^–1 shell) andCaCO_s (%CaCO₃ of total clam dry weight). Habitat waters wereassessed for total hardness (expressed as ppm CaCo₃), ppm Ca,ppm Mg, conductivity (µmho) and suspended organic Carbon(µgCl^–1). For all populations, shell organic C andN are positively correlated and there is an inverse relationshipbetween the amounts of shell CaCO₃ and shell organic carbon.Trophic considerations give the best correlation with shelltype at the generic level of consideration since species ofMusculium are found at the opposite end of the trophic scale(eutrophic) from all other populations studied. For S. striatinum,the most extensively studied species, the amount of shell CaCO₃is inversely related to water hardness. The selection of shellsin the Sphaeriidae is discussed in relation to structural-functionalneeds and habitat conditions ¹ Present Address: Department of Biology, Syracuse University,Syracuse, New York 13210, U.S.A. ² Present Address: Department of Zoology, Miami University,Oxford, Ohio 45056, U.S.A. (Received 5 December 1978;     

CHANGES IN GLYCERALDEHYDE 3-PHOSPHATE DEHYDROGENASE ACTIVITY IN SHOOT APICAL MERISTEMS OF BRASSICA CAMPESTRIS DURING TRANSITION TO FLOWERING

An assay system has been developed for the histochemical determination of glyceraldehyde 3-phosphate dehydrogenase (G3PD) activity to indicate glycolytic pathway capacity during evocation in the shoot apical meristem of Brassica campestris L. G3PD activity was differentially distributed in a zonate pattern within the meristems at the vegetative, the transition, and the floral stages. The activity of G3PD changed in all apical zones of evoked apices, but especially in the central and the peripheral zones of apices at the prefloral stage. In the prefloral stage of development heavy enzyme activity was localized in island-like areas within the peripheral zone. These results indicate that 1) the capacity of glycolysis fluctuates during evocation, 2) during floral evocation the capacity of the glycolytic pathway parallels the capacity of the citric acid cycle and the electron transport system only at the prefloral stage, and 3) G3PD activity marks incipient floral primordia. It is proposed that the enzymic marking of an incipient floral primordium indicates the end of evocation in Brassica.     

A QUANTITATIVE STUDY OF CELLULAR EVENTS IN THE SHOOT APICAL MERISTEM OF BRASSICA CAMPESTRIS (CRUCIFERAE) DURING TRANSITION FROM VEGETATIVE TO REPRODUCTIVE CONDITION

Vegetative plants were induced to flower by 16-hr-long days. Apical buds were collected at intervals during several developmental phases up to 63 hr. A stereologic analysis and mitotic index study was conducted on median longitudinal sections of shoot apical meristems. A rise in the mitotic index occurred between 12 and 24 hr within central, peripheral and pithrib meristem zones. Preceding the floral stage a second increase in the mitotic index was observed in peripheral and central zones, but not in the pith-rib meristem zone. A significant rise in apical volume, cell number, height, and width began in the transitional stage and continued to the floral stage. Significant correlation coefficients were observed between these apical parameters. Relative volume and cell population of each zone remained constant from the vegetative to the reproductive stage. Volume fraction occupied by the nucleus and nucleolus remained constant within each zone during the same time period. In each zone the volume of the nucleus was significantly correlated to volume of the nucleolus. It appears a pre-inflorescence apex, while larger, is structurally similar to a vegetative apex.