有机物质对紫球藻生长的影响

研究了有机碳、氮源扩B族维生素对紫球藻生长的影响。葡萄糖促生长作用最佳,添加2％（W／V）葡萄糖时,藻细胞生长速度比对照组明显提高,培养10d收获的生物量增加92.6％,培养液中的溶解氧含量和藻体叶绿素a含量也有变化,有机氮源的利用率低,仅蛋白胨、酵母汁可被利用。维生素B2和B12也有促长作用。     

有机物质对紫球藻生长的影响*

研究了有机碳、氮源及 B族维生素对紫球藻生长的影响。葡萄糖促生长作用最佳 ,添加 2 % (W/V)葡萄糖时 ,藻细胞生长速度比对照组明显提高 ,培养 10 d收获的生物量增加 92 .6 % ,培养液中的溶解氧含量和藻体叶绿素 a含量也有变化。有机氮源的利用率低 ,仅蛋白胨、酵母汁可被利用。维生素 B2 和 B12 也有促长作用。     

Cd2+对紫球藻生长及光化学活性的影响

以紫球藻(Porphyridium purpureum)为供试材料, 研究了5个不同浓度的Cd2+对紫球藻的细胞密度、叶绿素a含量、藻红蛋白含量及ATP含量的影响, 以及对紫球藻的最大光量子产额(F_v/F_m)、实际光量子产额(YII)、相对电子传递效率(ETR)及非光化学淬灭(NPQ)的影响, 探讨了各荧光参数在不同浓度的Cd2+胁迫下的变化规律。研究结果表明, 在Cd2+胁迫的6d内, 紫球藻的生长速度显著下降, 且Cd2+的浓度越高, 生长速度下降越快; Cd2+胁迫显著的减少叶绿素a、藻红蛋白及ATP含量, 且浓度越高, 减少的幅度越大; 在Cd2+浓度低于200 μmol/L时, 紫球藻的叶绿素荧光参数F_v/F_m、YII及ETR呈现先下降后上升的趋势,而且随着胁迫时间的延长, 下降幅度逐步增大; NPQ在低浓度下(<200 μmol/L)呈现显著上升趋势, 高浓度下(>500 μmol/L)呈现显著下降趋势。因此, 水体中浓度超过50 μmol/L的Cd2+就会显著影响紫球藻的生长及光化学活性, 水生环境中不断累积的Cd2+将会对紫球藻的生态平衡产生影响。     

紫球藻的培养与利用（综述）

紫球藻为单细胞红藻,其细胞富含红藻多糖、多不饱和脂肪酸(主要为AA和EPA）及藻胆蛋白等高价值生物活性物质,在医药和精细化工领域有广泛的应用前景。本文综述紫球藻的生物学特性、生物活性物质、培养与培养特性等方面的研究概况。     

倍频Nd：YAG激光对紫球藻生长与胞外多糖产量的影响

紫球藻经Nd:YAG激光（波长1060nm)照射,以不同时间设置处理剂量,比较紫球藻细胞活力,生长速率,生物量,胞外多糖产量等方面的变化。高剂量处理组（Y-20、Y-30和Y-40）致死率为17-44%,继代培养后生长迅速,K值分别比对照组提高18%、23.4%和15.3%,各处理组培养10天后收获的生物量与对照组无显著差异,但胞外多糖产量均有较大幅度提高,增幅达50-150%。此外,YAG激光照射对藻细胞叶绿素含量也有影响,YAG激光有望成为紫球藻优良藻株选育的较佳诱变剂。     

半导体激光对紫球藻生物学效应的影响

采用波长650nm,功率40mW,功率密度13W／cm^2的半导体激光,对紫球藻（Porphyridium cruentum)进行诱变,辐照时间分别为5min、10min、20min。通过对紫球藻每天细胞数、叶绿素a、第7d细胞干重和胞外多糖产量的测定可知：与对照组比较,3个处理对紫球藻生长及胞外多糖产生影响,5min、10min均有不同程度的促进作用,其中5min作用最明显,而20min则有抑制作用。     

倍频Nd∶YAG激光对紫球藻生长与胞外多糖产量的影响

紫球藻经Nd:YAG激光(波长1060 nm)照射,以不同时间设置处理剂量,比较紫球藻细胞活力、生长速率、生物量、胞外多糖产量等方面的变化.高剂量处理组(Y-20、Y-30和Y-40)致死率为17～44%,继代培养后生长迅速,K值分别比对照组提高18%、23.4%和15.3%.各处理组培养10天后收获的生物量与对照组无显著差别,但胞外多糖产量均有较大幅度提高,增幅达50～150%.此外,YAG激光照射对藻细胞叶绿素含量也有影响.YAG激光有望成为紫球藻优良藻株选育的较佳诱变剂.     

通入CO2和补加氮源对紫球藻生长和代谢物质积累的影响

论文研究了柱状光生物反应器中CO2浓度和氮源添加模式等培养条件对紫球藻(Porphyridium sp.UTEX 637)生长和主要代谢产物积累的影响。结果表明,通入CO2能显著促进紫球藻的生长及胞外多糖、水溶性蛋白和总脂等生物活性物质的积累,其中1%的CO2浓度对紫球藻的生长及活性物质积累最有利,该条件下紫球藻的最高干重可达到8.14 g/L,是对照组的4.93倍;胞外多糖产量明显高于对照组,最高可达到238.8 mg/L;补加氮源KNO3对紫球藻生长及胞外多糖、水溶性蛋白含量均有明显的促进作用,最高干重、胞外多糖含量可分别达到对照组的1.5倍和1.25倍,但不利于总脂的积累。     

绿光条件下氮浓度对紫球藻生长和生物活性产物合成的影响

本文以紫球藻FJ-12为藻株,在发光二极管(LED)绿光条件下,研究不同氮浓度(0、0.5、1和1.5 g/L)对紫球藻细胞的生长和生物活性产物(藻胆蛋白、胞外硫酸酯多糖和多不饱和脂肪酸)合成的影响.结果 表明:在氮浓度为1 g/L的条件下,紫球藻可获得最大生物量,为3.09 g/L.藻细胞在氮浓度为1 g/L和1.5...     

紫球藻及其多糖抗菌性能初探

本文报道紫球藻提取液及其多糖溶液抗病原细菌、真菌性能的研究结果。采用管碟法分别测定紫球藻培养分泌物、藻体破碎后的水提物和醇提物、胞外多糖和胞内多糖水溶液等的抗菌能力。结果表明,各样品均有一定抗菌能力,紫球藻水提物和胞外分泌物抗菌性能较强。经比较分析,多糖是抗菌作用的主要组分。紫球藻提取物及其多糖对革兰氏阳性细菌(特别是对金黄色葡萄球菌和八叠球菌)的抑菌作用较为明显,具有一定开发价值。     

Effects of abscisic acid on nucleic acid metabolism in maize coleoptiles

Summary Following treatment with ABA an inhibition of total RNA synthesis was observed after 30 hours. Total soluble ribonuclease activity did not change during the first 8 hours, after which an increase could be observed.Separation of nucleic acids with polyacrylamide gel electrophoresis indicated that synthesis of soluble RNA was less inhibited by ABA than synthesis of ribosomal RNA.Effects of 5-FU and ABA on ribosomal RNA precursor were investigated. It could be shown that 5-FU did not inhibit ribosomal precursor synthesis, but that ABA did so.     

Effects of abscisic acid on in vitro growth of cotton fiber

Summary Abscisic acid (ABA) inhibits in vitro growth of cotton (Gossypium hirsutum L.) fiber and is effective only when applied during the first four days of culture started on the day of anthesis. Abscisic acid causes a small increase in potassium uptake by the ovules and also enhances leakage of potassium from them. During their period of rapid growth, fibers produced by ABA-treated ovules have a higher potassium content and a lower malate content as compared to fibers on untreated control ovules. Results are discussed in the light of earlier reports on the in vitro growth of cotton fiber and effects of abscisic acid on other plant tissues. It is suggested that ABA inhibits fiber growth, in part, by interfering with malate metabolism.Abbreviations ABA abscisic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - TFU total fiber units     

Effects of abscisic acid and its related compounds on rice seedling growth

Rice seedlings with the mesocotyl and coleoptile (the undeveloped leaves enclosed in the coleoptile) are here referred to as MC type seedlings and are considered to be suitable for deep sowing. We investigated the effects of abscisic acid (ABA) and several of its related compounds on the occurrence of MC type seedlings and on rice mesocotyl growth. Rice (Oryza sativa L. cv. JC 91) seedlings were grown on 0.8% agar medium in the presence or absence of various kinds of ABAs under aseptic conditions at 30 °C in the dark for 14 days. The activity of the R isomer of ABA (R-ABA) was slightly less than that of the naturally occurring S form (S-ABA) concerning the occurrence of MC type rice seedlings and the growth of the rice mesocotyl. In addition, the racemate of R-and S-ABA (RS-ABA) is less effective than R-ABA and S-ABA alone.Trans-ABA had no activity in relation to both percent occurrence of MC type seedlings and mesocotyl growth. The results of the present study suggest that the occurrence of MC type rice seedlings and the growth of rice mesocotyls were closely related to structure-activity relationships with analogs of ABA.     

Effects of abscisic acid on the secondary metabolism of cultured Onosma paniculatum cells

ABA addition to B5 or M9 medium at the concentrations from 0.1 to 5.0 mg/l suppressed growth of Onosma paniculatum cells. The addition of these ABA concentrations to M9 medium also significantly decreased the formation of shikonin and its derivatives in the cultured cells during the entire course of culturing. The enzyme activity assay showed that, on the 4th day after inoculation, 0.1 mg/l ABA significantly decreased the activities of phenylalanine ammonia-lyase, the first enzyme, and p-hydroxybenzoic acid-geranyltransferase, a key enzyme involved in shikonin biosynthesis. However, no significant change in these two enzyme activities was found during the following days for testing (8, 12, and 16 days). Interestingly, RT-PCR analysis of the PAL1 and LePGT1 gene expression showed no significant changes on the 4th day after inoculation. Furthermore, we found that the inhibitory effect of ABA on the secondary metabolism could be alleviated significantly by the addition of 2-aminoethyl diphenyl borate (an inhibitor of inositol triphosphate-receptor) or nicotinamide (an inhibitor of ADP-ribose cyclase), which functions by decreasing the intracellular calcium concentration. Published in Russian in Fiziologiya Rastenii, 2007, Vol. 54, No. 4, pp. 597–603. The text was submitted by the authors in English.     

Regulation of hormone metabolism in Arabidopsis seeds: phytochrome regulation of abscisic acid metabolism and abscisic acid regulation of gibberellin metabolism

In a wide range of plant species, seed germination is regulated antagonistically by two plant hormones, abscisic acid (ABA) and gibberellin (GA). In the present study, we have revealed that ABA metabolism (both biosynthesis and inactivation) was phytochrome-regulated in an opposite fashion to GA metabolism during photoreversible seed germination in Arabidopsis. Endogenous ABA levels were decreased by irradiation with a red (R) light pulse in dark-imbibed seeds pre-treated with a far-red (FR) light pulse, and the reduction in ABA levels in response to R light was inhibited in a phytochrome B (PHYB)-deficient mutant. Expression of an ABA biosynthesis gene, AtNCED6, and the inactivation gene, CYP707A2, was regulated in a photoreversible manner, suggesting a key role for the genes in PHYB-mediated regulation of ABA metabolism. Abscisic acid-deficient mutants such as nced6-1, aba2-2 and aao3-4 exhibited an enhanced ability to germinate relative to wild type when imbibed in the dark after irradiation with an FR light pulse. In addition, the ability to synthesize GA was improved in the aba2-2 mutant compared with wild type during dark-imbibition after an FR light pulse. Activation of GA biosynthesis in the aba2-2 mutant was also observed during seed development. These data indicate that ABA is involved in the suppression of GA biosynthesis in both imbibed and developing seeds. Spatial expression patterns of the AtABA2 and AAO3 genes, responsible for last two steps of ABA biosynthesis, were distinct from that of the GA biosynthesis gene, AtGA3ox2, in both imbibed and developing seeds, suggesting that biosynthesis of ABA and GA in seeds occurs in different cell types.     

Effects of exogenous abscisic acid on leaf carbohydrate metabolism during cucumber seedling dehydration

Cucumber (Cucumis sativus L.) seeds were pretreated with exogenous abscisic acid (ABA) prior to germination. After germination, seedlings with three leaves were exposed to gradual dehydration. The effects of ABA on photosynthetic rate (Pn), daily water loss (WL) and water utilization efficiency (WUE) during dehydration were investigated, in addition to the variation of carbohydrates in leaves. ABA improved the Pn, WL and WUE of cucumber seedlings during dehydration. After rehydration, the seedlings pretreated with ABA showed a higher recovery in Pn, WL and WUE, as compared to those without an ABA pretreatment. Subsequent to dehydration, concentration of stachyose, raffinose, sucrose, glucose, and fructose increased in seedlings pretreated with ABA. Dehydration altered the proportions of the sugars in the total carbohydrates, and accelerated the accumulation of stachyose, raffinose and sucrose. After rehydration, carbohydrate concentrations of seedlings pretreated with ABA recovered to levels observed prior to dehydration. These results demonstrated that pretreatment of seeds with exogenous ABA enhanced carbohydrate tolerance to dehydration of cucumber seedlings.     

Effects of NaCl and KNO3 concentrations on the abscisic acid content of Dunaliella sp. (Chlorophyta)

Abscisic acid (ABA) is a hormone which has a number of roles during the life cycle of a plant. We demonstrated the occurrence of ABA in a halotolerant green alga, Dunaliella sp. isolated from a salt pond near Adelaide, South Australia, using thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The variation of cellular ABA and protein content during the growth of an axenic clonal culture of Dunaliella sp. was investigated under different concentrations of NaCl and KNO₃.Experimental results can be summarized as follow: (1) ABA content was changed with the growth stage of culture: A rapid increase in ABA content was observed in the logarithmic phase. After this, the content rapidly decreased to very low values. (2) ABA content was also affected by the NaCl concentration. The content had a minimum value at the NaCl concentration (15%) where growth rate was maximal, and higher values at higher or lower concentrations of NaCl. (3) The ABA content also increased with decreasing nitrogen concentration of the medium.