Cytokinin activation of Arabidopsis cell division through a D-type cyclin

Cytokinins are plant hormones that regulate plant cell division. The D-type cyclin CycD3 was found to be elevated in a mutant of Arabidopsis with a high level of cytokinin and to be rapidly induced by cytokinin application in both cell cultures and whole plants. Constitutive expression of CycD3 in transgenic plants allowed induction and maintenance of cell division in the absence of exogenous cytokinin. Results suggest that cytokinin activates Arabidopsis cell division through induction of CycD3 at the G1-S cell cycle phase transition.     

激素调控植物顶端优势的分子生物学进展

分子生物学中对基因与突变体的研究表明植物的顶端优势现象是受激素的调控的,其中生长素抑制侧芽的生长,而细胞分裂素促进侧芽的起始,二者的比值对植物的生长更加重要。研究还表明其他的激素也参加了植物顶端优势的调控过程,如ABA、GA等。植物的顶端优势是基因、激素及植物发育时期综合作用的结果。     

紫参试管苗生产中植物激素及其浓度筛选研究

试验表明,在紫参(Salvia chinensis Benth)试管苗生产中,把叶片培养在附加 NAA 0.2 mg/I BA0.5mg/I的 MS 培养基上,叶片外植体能在4周内产生大量不定芽,芽数高达265.4个/4块外植体。筛选试验证明,上述培养基中的激素种类及浓度都是紫参试管苗生产中最合适的。     

细胞分裂素对红掌愈伤组织不定芽分化与增殖的影响

[目的]研究细胞分裂素对红掌组培苗繁殖速度及质量的影响。[方法]以继代培养第6代的愈伤组织为试验材料,探讨了ZT、TDZ、6-BA 3种细胞分裂素及其浓度对不定芽分化及变异的影响。[结果]在使用浓度2.0~8.0 mg/L的范围内,随着细胞分裂素浓度的增加,正常不定芽的分化数及叶片数呈下降趋势,而异常不定芽分化逐渐增多,且随着培养时间的延长,这种影响变得更加明显;3种细胞分裂素的培养效果具有显著差异,ZT和6-BA添加浓度分别在2.0和4.0 mg/L以下时,其正常不定芽分化较多,不良变异率较少,而TDZ在0.5 mg/L时已显著抑制了正常不定芽的分化,同时易产生异常不定芽。[结论]3种细胞分裂素作用的强弱依次为TDZZT6-BA;在红掌愈伤组织继代培养诱导不定芽过程中,应避免使用高浓度细胞分裂素。     

植物激素在离体培养苦楝中对芽及嫩梢的增殖效应

本文研究了10年生苦楝返幼茎段离体培养中植物激素对芽及嫩梢的增殖效应。方差分析表明,BAP决定了每个外植体上的芽数,而NAA决定了丛芽率(%)。对于芽增殖,最佳BAP:KT为1:1。对于有效嫩梢增殖,细胞分裂素和生长素之间具有极显著的交互效应。细胞分裂素的作用大于生长素,而BAP的作用大于KT,NAA的作用大于IBA。芽及有效嫩梢增殖最佳的激素组合为BAP0.5ppm NAA0.005ppm,BAP:NAA的最佳比例为100:1。     

噻苯隆对月季芽增殖及月季叶片愈伤诱导的影响

为研究噻苯隆( TDZ)对月季的影响,以皇家巴西诺月季的茎段和叶片为外植体,MS为基本培养基,添加一定浓度的细胞分裂素和生长素及不同浓度的TDZ,对其芽增殖和叶片愈伤组织诱导进行了研究.结果表明:促进侧芽增殖的最佳培养基为MS+NAA 0.lmg/L+6BA1.0mg/L+TDZ 2.0mg/L,诱导月季叶片形成愈伤的最佳培养基为MS+NAA 0.5mg/L+2,4D5.0 mg/L+ TDZ 1.0mg/L,0.5 cm×1.0 cm的切块有利于愈伤组织的产生.     

壳寡糖浸种对马铃薯微型薯芽生长和内源激素含量的影响

【目的】浸种处理是马铃薯生产中常用的促进块茎萌发的手段，然而浸种剂使用不当，会引起内源激素的失调，导致马铃薯高脚苗的发生。研究壳寡糖浸种对马铃薯微型薯芽生长及内源激素含量的影响，为壳寡糖作为马铃薯微型薯拌种剂的安全使用提供理论支持。【方法】以‘费乌瑞它’马铃薯微型薯为试材，分别用10、50和200 mg·L^-1(w/v)的壳寡糖溶液浸种处理，筛选促芽生长的最佳壳寡糖浓度，以50 mg·L^-1(w/v)浸种15 min为处理组(COS₅₀)，蒸馏水浸种为阴性对照(Con)，并选择易引起块茎芽细长且疯长的外源赤霉素3(15 mg·L^-1,w/v)浸种处理为阳性对照(GA₃)。测定各处理对微型薯发芽率、发芽势、芽长和芽直径的影响，并检测浸种处理前(BT)、萌发前期(BGS)、萌发期(GS)和伸长期(VG)顶芽内源激素含量的变化，用石蜡切片染色观察GS期顶芽细胞的形态，采用Pearson相关分析研究芽生长与内源激素含量的内在联系。【结果】50 mg·L^-1(w/v...     

不同因素对沙芥腋芽增殖的影响

采用无菌茎尖苗诱导腋芽作为外植体,研究培养基类型、细胞分裂素种类和浓度、生长素种类和质量浓度、6-BA(6-苄基嘌呤)和IBA(吲哚丁酸)不同质量浓度组合、AgNO3(硝酸银)质量浓度5个因素对沙芥腋芽增殖的影响。结果表明,MS(Murashige and Skoog)培养基中腋芽的增殖倍数最高达到5.27,最适宜沙芥腋芽增殖培养;3.0~5.0mg/L的细胞分裂素6-BA是最适合沙芥腋芽增殖的细胞分裂素种类及质量浓度;0.1mg/L IBA是最适宜腋芽增殖的生长素种类及质量浓度;在3.0mg/L 6-BA和0.1mg/L IBA质量浓度组合的MS培养基中,沙芥腋芽的增殖倍数高达7.43;AgNO3显著降低腋芽增殖倍数和丛生芽诱导率。     

白鹃梅离体快繁技术的研究

[目的]探讨白鹃梅离体快速繁殖技术。[方法]以MS为基本培养基,附加不同种类、不同浓度细胞分裂素(6-BA、KT)和生长素(IBA、NAA),诱导离体白鹃梅快速繁殖。[结果]结果表明,较低浓度的细胞分裂素6-BA、KT和生长素IBA混合使用,有利于诱导芽增殖,其中以MS+0.3 mg/L IBA+0.5 mg/L 6-BA配方最佳。用1/2 MS附加0.1~0.3 mg/L NAAI、BA均能诱导生根,其中以1/2 MS+0.3 mg/LNAA配方最佳。     

6-苄基腺嘌呤对水稻颖花分化影响机制的研究

以常规籼稻品种扬稻6号为材料,在盆栽条件下,于生长锥伸长期外喷6-苄基腺嘌呤(6-BA)后,定期取样,测量穗部细胞分裂素(cytokinins,CKs)含量,同时采用RT-PCR检测水稻穗分化过程中细胞分裂素氧化酶基因(OsCKX2)的表达模式,考察水稻穗部性状.结果发现:6-BA处理促进水稻穗长发育并显著提高每穗枝梗和颖花数,分化枝梗数和总颖花数分别为60和255.4,比对照分别提高了10%和30.5%.穗部细胞分裂素含量的增加,刺激了更多颖花分化.6-BA 处理的水稻穗部OsCKX2表达时间提前,但表达量下降.认为:水稻穗分化始期喷施6-BA可降低穗部OsCKX2的表达强度,提高穗部细胞分裂素含量,对枝梗和颖花分化产生促进作用,为形成大穗提供了先决条件.     

Dormancy Characteristics of Malus ‘Snowdrift’ and Effects of Spraying 6-benzyladenine on Its Germination and Flowering in Long-day Treatment

[Objective] The dormancy characteristics of Malus ‘Snowdrift’ in long-day treatment were studied, and 6-BA was used to break the dormancy, with the aim to achieve the purpose of flowering in autumn. [Method] The new shoots of ‘Snowdrift’ in long-day treatment were conducted with hydroponics to investigate their dormancy time. And cytokinin 6-benzyladenine(6-BA)was used to treat the dormant shoots, to investigate the budding, flowering and flower bud differentiation. [Result] The shoots in long-day treatment entered endodormancy after August 7~(th) and the shoots in the natural daylight entered endodormancy before July 18~(th). In long-day treatment, 116 buds, 198 flowers were observed after 6-BA spraying. [Conclusion] The optimum concentration of 6-BA was 300 mg/L. And the flower bud differentiation of ‘Snowdrift’ in long-day treatment was faster than those in natural daylight after 6-BA spraying.     

植物激素与果树花芽分化

综述了近十年来果树花芽分化的一些研究进展,主要从细胞分裂素、赤霉素、生长素、脱落酸、乙烯等激素及其平衡等方面介绍花芽分化的研究进展。细胞分裂素和乙烯对果树花芽分化有促进作用;赤霉素则对果树花芽分化有抑制作用;生长素在花芽分化中的作用与营养的输入有关;脱落酸在果树花芽分化中的作用目前意见不一致。     

加工番茄离体再生体系的建立

以加工番茄B04子叶盘和下胚轴切段为外植体,研究了不同种类和浓度的细胞分裂素(ZT、6-BA和KT)和生长素(IAAI、BA和NAA)组合及附加物AgNO3对外植体不定芽诱导的影响。结果表明,细胞分裂素ZT的不定芽诱导效果明显优于6-BA和KT,KT诱导效果最差;生长素IAA的不定芽诱导效果优于IBA和NAA;在不同的激素组合中,不定芽诱导率最高的培养基为MS 2.0 mg/L ZT 0.2 mg/L IAA。再生芽在MS 0.1mg/L IAA生根培养基上能正常生根,并发育成完整的小植株。     

膏桐叶片再生植株体系的建立

[目的]研究不同激素组合对离体叶片再生体系建立的影响。[方法]选用6-BA与KT为分裂素,以无菌苗的离体叶片为外植体,在MS培养基中进行不定芽诱导,经增殖培养后,用生长素NAA、IBA促进生根,从而判断不同激素对不同外植体诱芽、增殖、生根的影响。[结果]在MS培养基中,单独使用分裂素6-BA或者KT与生长素NAA的组合都不能较好地对叶片进行不定芽的诱导。在同时添加1.00mg/L的6-BA和KT以及0.03mg/L的NAA后对不定芽的诱导效果最好,诱导率达90%;加入0.50mg/L的6-BA、0.50mg/L的KT和0.02mg/L的NAA后,不定芽的增殖和伸长效果较好;在加入0.10mg/LNAA的MS培养基上生根效果最佳。[结论]以MS培养基用适量浓度植物激素诱导膏桐离体叶片,可建立稳定的再生体系,为膏桐的组培扩繁体系提供了一种新的选择。     

Spatially resolved calcium dynamics of mammalian Purkinje cells in cerebellar slice

Microfluorometric imaging was used to study the correlation of intracellular calcium concentration with voltage-dependent electrical activity in guinea pig cerebellar Purkinje cells. The spatiotemporal dynamics of intracellular calcium concentration are demonstrated during spontaneous and evoked activity. The results are in agreement with hypotheses of dendritic segregation of calcium conductances suggested by electrophysiological experiments. These in vitro slice fluorescence imaging methods are applicable to a wide range of problems in central nervous system biochemical and electrophysiological functions.     

In vivo Ca2+ dynamics in a cricket auditory neuron: an example of chemical computation

Fura-2 calcium imaging in the cricket omega neuron revealed increased intracellular free calcium ion concentration in response to simulated cricket calling songs and other sound stimuli. The time course of the increase and decrease in intracellular calcium coincided with the time course of forward masking, a time-dependent modulation of auditory sensitivity. The buffering of calcium transients with high concentrations of a kinetically fast calcium buffer eliminated the post-stimulus hyperpolarization associated with forward masking, whereas the uncaging of calcium inside the neuron produced a hyperpolarization. The results suggest that sound-stimulated intracellular calcium accumulation acts by means of a calcium-activated hyperpolarizing current to produce forward masking. These findings underscore the importance of chemical dynamics in neural computation by demonstrating a behaviorally relevant role of calcium dynamics in vivo.     

梨矮化砧优系'青砧D1'叶片离体培养再生体系的建立

"青砧D1"是青岛农业大学选育的一个梨矮化砧优系.本试验研究了不同浓度的TDZ、6-BA、IBA及IAA配比对"青砧D1"叶片离体再生培养的影响,从而为该砧木的快速繁殖和应用推广奠定基础.结果表明:MS培养基中附加适宜浓度和配比的6-BA与IBA能提高初代培养外植体的成活率,以6-BA 1.0 mg·L-1与IBA 0.1 mg·L-1浓度配比的外植体成活率最高,达86.3%.NN69培养基中附加不同浓度的TDZ与IBA或IAA能有效地诱导叶片外植体不定芽再生,以TDZ和IBA配合诱导产生不定芽的外植体比例高,在TDZ 4.0 mg·L-1与IBA 0.3 mg·L-1配比组合下可达到100%,但平均外植体再生芽数为3个,低于TDZ与IAA配比组合(3.9个/外植体).在所试的不同浓度TDZ与IAA配比组合中,外植体不定芽诱导率最高仅为68%.MS培养基中附加6-BA 1.0 mg·L-1和IBA 0.2 mg·L-1时芽增殖系数最高,达4.42.在1/2 MS培养基中附加IBA 0.3 mg·L-1时生根率最高,达87.3%,移栽成活率达95%.     

盐生植物盐角草同化枝不定芽的诱导与增殖

【目的】建立并确定盐生植物盐角草(Salicornia europaea L)同化枝不定芽诱导与增殖的试验体系和培养基。【方法】以MS为基本培养基,通过附加不同浓度激素(TDZ、NAA、6-BA)及盐(NaCl)进行盐角草不定芽的诱导,筛选诱导盐角草不定芽的最适激素配比及盐浓度;后期通过对细胞分裂素TDZ浓度(0、1.6、1.8、2.0和2.5 mg/L)的摸索,确定盐穗木不定芽增殖的最适浓度。【结果】盐角草同化枝在含有200 mM NaCl的MS₃(2.0 mg/L TDZ、0.1 mg/L NAA)培养基中不定芽诱导率达32.4%,显著高于(P<0.05)其余组,为最适诱芽培养基。再生的不定芽在含有2.0 mg/LTDZ的培养基中经过30~40 d的培养,不定芽增殖率可达619.5%。盐角草不定芽诱导及增殖最适培养基均为:MS+2.0 mg/L TDZ+0.1 mg/L NAA+200 mM NaCl。【结论】一定浓度的TDZ、NAA及NaCl组合,可通过直接器官发生途径有效诱导盐角草同化枝不定芽的产生和增殖。     

Intracellular calcium: its movement during pentylenetetrazole-induced bursting activity

The intracellular calcium concentration in the cytoplasm decreased and the calcium concentration near the cell membrane increased during bursting activity induced by pentylenetetrazole in snail neuron. Incubation in medium containing cobalt chloride or lanthanum chloride did not change this tendency, which suggests that this calcium distribution change is due to the stored calcium in the subcellular structure moving toward the cell membrane.     

Regulation of calcium concentration in voltage-clamped smooth muscle cells

The regulation of intracellular calcium concentration in single smooth muscle cells was investigated by simultaneously monitoring electrical events at the surface membrane and calcium concentration in the cytosol. Cytosolic calcium concentration rose rapidly during an action potential or during a voltage-clamp pulse that elicited calcium current; a train of voltage-clamp pulses caused further increases in the calcium concentration up to a limit of approximately 1 microM. The decline of the calcium concentration back to resting levels occurred at rates that varied with the calcium concentration in an apparently saturable manner. Moreover, the rate of decline at any given calcium concentration was enhanced after a higher, more prolonged increase of calcium. The process responsible for this enhancement persisted for many seconds after the calcium concentration returned to resting levels. Thus, the magnitude and duration of a calcium transient appear to regulate the subsequent calcium removal.