氮源种类及浓度对眼点拟微绿球藻生长密度、油脂产率和二十碳五烯酸含量的影响

氮源是影响微藻生长和油脂积累的重要因素,文中通过单因素试验比较了NaNO3、CO(NH2)2、NH4Cl、CH3COONH4及其浓度对眼点拟微绿球藻生长密度、生长速率、油脂产率、二十碳五烯酸(EPA)含量的影响。结果表明：NH4+更易被眼点拟微绿球藻利用,能更好地促进微藻生长和油脂积累;氮浓度的增加有利于微藻的生长和藻油脂肪酸的去饱和,但不利于微藻油脂的积累。在实验考察的氮源种类和浓度范围内,CH3COONH4是促进眼点拟微绿球藻生长和油脂积累、EPA生成的适宜氮源,其适宜的浓度为5.29 mmol/L。     

外源海藻糖对PEG渗透胁迫下小麦Rubisco及其活化酶的影响

以抗旱品种‘晋麦47’和干旱敏感品种‘郑引1号’为材料,通过室内水培试验研究了外源海藻糖对PEG渗透胁迫下小麦叶片净光合速率、1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)和1,5-二磷酸核酮糖羧化酶/加氧酶活化酶(RCA)含量和相关基因表达特性的影响。结果表明:(1)外源海藻糖和渗透胁迫均能显著增加2个小麦品种叶片海藻糖含量。(2)渗透胁迫显著降低了2个品种小麦叶片的净光合速率,而外源海藻糖能显著缓解受胁迫小麦叶片净光合速率的降低幅度。(3)渗透胁迫仅使‘郑引1号’Rubisco大亚基基因(rbcL)相对表达量及相应蛋白含量显著降低;渗透胁迫显著降低了小麦RCAα和β亚基基因相对表达量,并显著降低RCA蛋白含量,而外源海藻糖不能缓解RCA蛋白含量的降低;渗透胁迫显著降低了Rubisco总活性、初始活性、活化状态及RCA活性,而外源海藻糖则能显著缓解上述酶活性的下降。(4)小麦叶片净光合速率与其rbcL、RCAα和β亚基基因相对表达量及Rubisco总活性、初始活性、活化状态及RCA活性均呈极显著正相关关系。研究发现,在渗透胁迫条件下,外源海藻糖主要从翻译后层面对小麦叶片Rubisco和RCA的活性发挥显著保护作用,从而缓解了小麦净光合速率的降低。     

不同光质对烟草叶片组织结构及Rubisco羧化酶活性和rbc、rca基因表达的影响

通过对烟草植株覆盖白、红、黄、蓝、紫色滤膜获得不同光质,研究了烟草叶片在7～70d的生长发育期内,不同光质处理对烟叶组织结构特征、核酮糖1,5-二磷酸羧化酶/加氧酶（Rubisco）羧化酶活性、Rubisco基因（rbc）表达及其活化酶（Rca）基因（rca）表达的影响。结果表明,与黄膜处理下生长的烟叶相比,红、蓝、紫膜处理下生长的烟叶有较高的叶片厚度、栅栏组织厚度、海绵组织厚度、栅栏细胞密度和较小的组织空隙率。此外,红、蓝、紫膜处理的叶片有较高的Rubis-co羧化酶活性和净光合速率及较强的rbc和rca基因表达。实验结果表明不同光质对烟草叶片的组织结构特征有显著影响,光质可能通过影响Rubisco羧化酶活性进而影响叶片光合效率,而光质、叶片组织结构和光合效率之间存在某种程度的相互联系。     

蔗糖对水稻幼苗叶片谷氨酰胺合成酶和1,5-二磷酸核酮糖羧化酶/加氧酶的影响

报道了在光照和暗处培养下,不同的浓度的蔗水稻幼苗叶片GS及其同工酶、1,5－二磷酸核酮糖羧化酶／加氧酶（Rubisco）的影响。无论是在光照或在暗处,蔗糖对GS活性均有抑制作用,尤其是在较高蔗糖下作用更为明显;虽然Rubisco及可溶性蛋白的水平在光照和暗处有显著的差别,但蔗糖对其未见明显影响。NativePAGE与活性染色表明,在光照下或在暗处,蔗糖对GS2的抑制蔗糖浓度升同而加强,但对GS1未有明显影响。这些结果提示,在水稻幼苗生长中,蔗糖不能象不光一样诱导叶水GS活性及其同工酶表达。     

宁波港压载水浮游植物多样性的研究

为了避免压载水作为媒介转移外来物种并造成污染危害,利用分子生物学技术研究宁波港来自印度洋、新加坡和美洲的压载水浮游植物。结果显示,新加坡和美洲的压载水没有检测到浮游植物。而印度洋的压载水里面含有硅藻门的直链藻属(Aulacoseirasp.)、海链藻属(Thalassiosirasp.)、骨条藻属(Skeletonemasp.)、冠盘藻属(Stephanodiscussp.)和星盘藻属(Discostellasp.);隐藻门的全沟藻属(Teleaulaxsp.)和斜片藻(Plagioselmissp.);绿藻门的括小球藻属(Chlorellasp.)、卵囊藻属(Oocystissp.)和Pseudococcomyxasp.;链形植物门包括新月藻属(Closteriumsp.)。同宁波港的港池浮游植物相比,生长速度快、抗逆性强的硅藻数量明鲜增多,有些种类是外来的。     

黄瓜叶片蛋白质双向电泳样品分级优化

以‘津研4号’苗期叶片为材料,采用聚乙二醇(PEG)分级沉淀法对黄瓜叶片蛋白质样品进行分级分离,将黄瓜叶片中存在的高丰度蛋白1,5-二磷酸核酮糖羧化酶/加氧酶特异性地集中于一个组分之中,以提高对黄瓜叶片蛋白质双向电泳中低丰度蛋白质的检测率.结果表明:(1)分级后各组分和全蛋白在SDS-PAGE谱带中差异显著,全蛋白得到了有效的分离.(2)二维电泳图谱上点的分辨率有很大的提高,所有组分的点数是未分级前的3倍之多.(3)浓度为24％的PEG-4000富集高丰度蛋白Rubisco的效果最好.该方法可推广应用于黄瓜叶片蛋白质组分析的样品制备.     

外源碳源和盐度对微拟球藻QA2生长和油脂积累的影响

微藻因生长速度快、含油量高、可作为生物柴油的优质原料而备受关注。本实验以一株海洋微拟球藻QA2为材料,研究了外源碳源的种类和浓度对其生长和油脂积累的影响。结果表明,以NaHCO3、CH3COONa和Na2CO3为外源碳源均能促进QA2藻株的生长,但以培养液中添加15mmol·L^-1CH3COONa对QA2藻株的生长和油脂积累的促进作用最为明显,总脂和脂肪酸的日产率分别是对照的2．73倍和5．67倍。同时利用叶绿素荧光技术研究了盐度对QA2光合作用的影响,表明QA2对盐度有较宽的适应范围,盐度在1．5％～6．0％范围内,不会对油脂产率造成明显的影响,但盐度增加能抑制QA2藻株PSII的电子传递,引起反应中心色素和捕光色素的降解,影响QA2的光合作用和生长,可见QA2培养的最适盐度应为3．0％。这为开放式规模培养微藻及其相关研究提供依据和参考。     

小麦叶片暗诱导衰老期间1,5-二磷酸核酮糖羧化酶/加氧酶的降解

研究了小麦(Triticum aestivum L. cv.Yangmai 158)叶片暗诱导衰老过程中1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco EC 4.1.1.39)的降解.发现在此期间Rubisco大亚基(LSU)发生裂解,产生50 kD的降解条带,同时在自然衰老过程中也检测到这一产物.初步实验结果表明LSU发生这步裂解时Rubisco全酶没有解离.另外,在粗酶液中当温度在30～35℃,pH 7.5时,这一步裂解反应能有效进行.     

不同叶位鸡蛋果叶片中核酮糖-1,5-二磷酸羧化酶/加氧酶的动力学特性

随着叶龄的增加,鸡蛋果Ru BP羧化酶/加氧酶的V_(max)(CO_2)值明显减小,K_m(O_2)值提高;K_m(CO_2)和V_(max)(O_2)值则保持相对的稳定。Ru BP羧化酶活性和Ru BP加氧酶活性均随叶龄增加而下降,但前者下降的速度高于后者,致使羧化/加氧此值也随叶龄增加而减小。     

水稻叶绿体DNA克隆片段的分析和rbcL基因在重组质粒上的定位

杂交灿稻(珍汕97B)的叶绿体DNA克隆到pBR 322载体上后,从克隆库中筛选出含核酮糖1.5-二磷酸羧化酶/加氧酶大亚基基因(rbcL)的重组子(19.3kb),用10种限制性内切酶分析了这个重组质粒并制作了完整的物理图谱,rbcL基因被定位在这个物理图谱上。     

变色酸显色法同时测定核酮糖-1,5-二磷酸羧化酶/加氧酶活性

提出一个用变色酸-硫酸显色浊同时测定核酮糖-1,5-二磷酸(RuBP)羧化酶/加氧酶活性的方法:RuBP羧化酶/加氧酶与底物作用后,用碱性磷酸酯酶将其产物水解生成乙醇酸和甘油酸,然后与变色酸试剂在1:5的体积比下,沸水浴中显色反应90min,乙醇酸与变色酸反应生成红紫色化合物,甘油酸生成淡棕色化合物,分别在573nm,745nm各有一特征吸收峰。根据A_(573),A_(745)与乙醇酸和甘油酸浓度间的函数关系式,求出RuBP羧化酶/加氧酶活性。     

Effect of salinity on growth,biochemical composition,and lipid productivity of Nannochloropsis oculata CS 179

Effect of salinity (15, 25, 35, 45, and 55‰) on growth, biochemical composition, and lipid productivity of Nannochloropsis oculata CS 179 was investigated under controlled cultivation in a 19‐day study. The results demonstrate that the dry biomass of N. oculata was the highest at a salinity of 25‰ among the treatments in the first 10‐day cultivation (P<0.05). During days 14–19 (stage III), the dry biomass productivity was the highest at a salinity of 35‰ (P<0.05). The algae had the highest chlorophyll a content (26.47 mg g^?1) at 25‰ in stage I, and it decreased continuously at stage III. Protein content (as% of dry biomass) of algae reached the highest value of 42.25 ± 2.10% at 15‰, and the lipid content was the highest of 32.11 ± 1.30% of dry biomass at 25‰. However, the lipid productivity of these algae was the highest at 35‰ (64.71 mg L^?1 d^?1; P<0.001). C16 series content was the highest among the total fatty acid methyl esters (FAME), and eicosapentaenoic acid C20:5n‐3 (EPA) content was high at the low salinity. Fatty acid profiles of N. oculata varied significantly under different salinities.     

草酸对氧化胁迫-水稻叶片中核酮糖-1，5-二磷酸羧化酶/加氧酶降解的保护作用

以杂交稻(汕优63)为试验材料,在木村B营养液中培养至三叶期,用草酸5mmol/L预处理水稻2d,再处以氧化胁迫(用0．1mmol／L浓度的活性氧诱发剂甲基紫精处理)。结果表明MV诱发的氧化胁迫下,Rubisco及其它可溶性蛋白快速降解。草酸预处理可明显缓解Rubisco及其它可溶性蛋白的降解,降解速率分别降低1／3和1／2左右。植株经草酸处理后其叶片中几种抗氧化酶如AsA-POD、SOD、CAT活性大大提高,这可能是草酸预处理可缓解氧化胁迫下Rubisco和其它可溶性蛋白降解的重要原因。既然草酸能有效地诱导植物的抗氧化防卫反应,它可能作为一种诱抗剂来提高植物的抗逆性。     

Effects of growth light and nitrogen nutrition on the organization of the photosynthetic apparatus in leaves of a C4 plant, Amaranthus cruentus

Properties of C4 photosynthesis were examined in Amaranthus cruentus L. (NAD-malic enzyme (ME) subtype, dicot) grown under different light and nitrogen (N) conditions, from the viewpoint of N investment into their photosynthetic components. In low-light (LL) leaves, chlorophyll content per leaf area was greater and chlorophyll alb ratio was lower than in high-light (HL) leaves. These indicate that LL leaves invest more N into their light-harvesting systems. However, this N investment did not contribute to the increase in the quantum yield of photosynthesis on the incident photon flux density (PFD) basis (Qi) in LL leaves. N allocation to ribulose 1,5-bisphosphate carboxylasel oxygenase (Rubisco) was significantly higher in HL-high N (HN) leaves than in other leaves. On the other hand, N allocation to C4 enzymes [phosphoenolpyruvate carboxylase (PEPC) and pyruvate Pi dikinase (PPDK)] was unaffected by the growth conditions. Maximum photosynthetic rates (Pmax) per Rubisco content were similar irrespective of the growth light treatments. Carbon isotope ratios (delta13 C) in the leaf dry matter were more negative in LL leaves than in HL leaves (LL = -19.3% per hundred, HL = -16.0% per hundred) and independent of leaf N. Vein density was highest in HL-HN leaves, and leaf thickness was unaffected by the growth light treatments. From these results, we conclude that A. cruentus leaves would not acclimate efficiently to low growth light.     

Evidence for the expression of morphological and biochemical characteristics of C3-photosynthesis in chlorohyllous callus cultures of Zea mays

A Zea mays callus culture containing chlorophyll was established and grown photomixotrophically. Cell chloroplast structure, and pigment and soluble protein contents were examined. Expression of some key enzymes of C₄ carbon metabolism was compared with that of etiolated (heterotrophic) and green photoautotrophic leaves. Chlorophyll content of the callus was 15–20% that of green leaves. Soluble protein content of callus was half that of leaf cells. Electron microscopic observations showed that green callus cells contained only typical granal chloroplasts. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.38) activities in green callus were ca 30% those of green leaves but 2–3 times higher than in etiolated leaves. Quantitative enzyme protein determination, using antibodies specific to maize leaf Rubisco showed that the chloroplastic carboxylase represented about 7% of total soluble protein in green callus, in parallel to its low chlorophyll content. The specific activity of Rubisco in callus and leaves was unchanged. Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activity in green callus was about 20% that of green leaves and similar to that measured in etiolated leaves. Apparent K_m (PEP) values (0.08 mM) for PEPC isolated from green callus and etiolated leaves were very different from values (0.5 mM) obtained with PEPC from green leaves. These kinetic characteristics together with the absence of inhibition by malate and activation by glucose-6-phosphate suggest that the properties of PEPC isolated from green callus and etiolated maize leaves are very similar to those of PEPPC from C₃ plants. Using PEPC antibodies specific to green maize leaf enzyme, immunotitration of PEPC preparations containing identical enzyme units allowed complete precipitation of the green leaf enzyme with increasing antibody volumes. In contrast, 60–70% of the activity of PEPC from etiolated and green callus was inhibited, suggesting low affinity for the maize green leaf PEPC antiserum (typical C₄ form). Ouchterlony double diffusion tests revealed only partial recognition of PEPC in green callus and etiolated leaves. NAD-malate dehydrogenase (NAD-MDH, EC 1.1.1.37) activity in callus was 2 and 3 times higher, respectively, than in etiolated and green leaves. NADP-malic enzyme (NADP-ME, EC 1.1.1.40) activity in callus cultures was much lower than in green leaves. All our data support the hypothesis that cultures of fully dedifferentiated chlorophyllous tissues of Zea mays possess a C₃-like metabolism.     

有机碳源对三角褐指藻生长、胞内物质和脂肪酸组分的影响

研究了3种有机碳对三角褐指藻生长、胞内物质和脂肪酸组分的影响。结果表明, 三角褐指藻具有利用有机碳进行兼养生长的能力, 生长速率加快, 倍增时间缩短, 生物量显著提高, 100 mmol/L甘油兼养的生物量最高(713 mg/L), 是自养(460 mg/L)的1.60倍, 乙酸钠和葡萄糖兼养的生物量分别是自养的1.28倍和1.21倍。兼养下蛋白质含量较自养明显下降, 碳水化合物和总脂含量高于自养, 乙酸钠和甘油兼养的总脂含量分别是自养的1.43倍和1.20倍, 葡萄糖兼养的总脂含量与自养无明显差异。3种有机碳兼养的饱和脂肪酸和单不饱和脂肪酸占总脂肪酸的比例增大, 多不饱和脂肪酸比例降低, EPA(eicosapentaenoic acid)比例降低, 乙酸钠兼养的胞内EPA含量(6.23%)和产量(36.59 mg/L)均高于自养, 分别是自养的1.10倍和1.40倍, 甘油和葡萄糖兼养的EPA含量和产量均低于自养。     

Decreased ribulose-1,5-bisphosphate carboxylase/oxygenase in transgenic tobacco transformed with 'antisense'rbcS.VIII. Impact on photosynthesis and growth in tobacco growing under extreme high irradiance and high temperature

Wild-type and antisense rbcS tobacco (Nicotiana tabacum) plants were grown in a glasshouse in midsummer in Portugal with an irradiance of 1500–2000 μmol m⁻²s⁻¹ and daytime temperatures of 30–35 °C. The Rubisco content of the transformants was lower by 35, 80 and over 90% than that of the wild-type. Gas exchange was measured over three separate days. There was a near-linear relation between Rubisco content and photosynthetic rate during the period of high irradiance, allowing a flux control coefficient of 0.83–0.89 to be estimated. The relation deviated slightly from linearity, because the internal CO₂ concentration (c;) was higher in the transformants than in the wild-type (190 and 275 μmol mol⁻¹ in plants with 35 and 80% less Rubisco, respectively, compared with 175 μmol mol⁻¹ for wild-type), compensating to some extent for the decreased Rubisco content. This increase in c_i occurred because the stomatal conductance (g) remained unaltered or was even higher in plants with decreased Rubisco, despite the lower rate of CO₂ assimilation. As a consequence, water use efficiency declined. The decreased rate of photosynthesis was not accompanied by a stoichiometric decrease in apparent growth rate. These results are discussed in relation to earlier studies of the plant set in growth cabinets. It is concluded that tobacco can adjust over a wide range of growth conditions to avoid a onesided limitation by Rubisco, but that in extreme environmental conditions this capacity to adapt is exhausted.     

Physiological nitrogen efficiency in rice: Nitrogen utilization,photosynthesis, and yield potential

Characteristics of rice (Oryza sativa) as a crop plant are briefly introduced, and the relationship between formation of yield potential and nitrogen (N) nutrition is described on the basis of studies using 15N as a tracer. In addition, the relationship between the leaf photosynthetic capacity and leaf N, and the factors limiting leaf photosynthesis under different growth conditions are reviewed. Finally, targets for improving rice yield potential are discussed with a focus on the role of increased photosynthesis efficiency in relation to leaf N status and the photosynthetic components in the leaves.     

Regulation of Rubisco by inhibitors in the light

2-carboxy-D-arabinitol-1-phosphate (CA1P) bound to Rubisco either in leaf extracts or after purification can be displaced by SO₄^2? ions. Thus, treatment of leaf extracts with a buffer containing 200 mol m^?3 SO₄^2? displaces any bound CA1P and enables measurement of maximum car-boxylation potential. In tobacco leaves, the activity following treatment with SO₄^?2 ions (‘maximal activity’) is greater than the total Rubisco activity. The ratio of the two activities altered in a dynamic way with fluctuations in irradiance. Even in species which do not produce significant amounts of CA1P, the maximal activity greatly exceeded the total activity. Anion exchange separation of components in acid extracts confirmed the absence of CA1P in tobacco leaves harvested above an irradiance of 300 μmol quanta m^?2 s^?1, but the presence of another inhibitor of Rubisco. These results are consistent with the regulation of Rubisco activity by inhibitors other than CA1P which, like CA1P, can be displaced by SO₄^2? ions.