Polyamine-dependent gene expression

The polyamines spermidine and spermine along with the diamine putrescine are involved in many cellular processes, including chromatin condensation, maintenance of DNA structure, RNA processing, translation and protein activation. The polyamines influence the formation of compacted chromatin and have a well-established role in DNA aggregation. Polyamines are used in the posttranslational modification of eukaryotic initiation factor 5A, which regulates the transport and processing of specific RNA. The polyamines also participate in a novel RNA-decoding mechanism, a translational frameshift, of at least two known genes, the TY1 transposon and mammalian antizyme. Polyamines are crucial for their own regulation and are involved in feedback mechanisms affecting both polyamine synthesis and catabolism. Recently, it has become apparent that the polyamines are able to influence the action of the protein kinase casein kinase 2. Here we address several roles of polyamines in gene expression.Received 27 November 2002; received after revision 9 January 2003; accepted 31 January 2003     

离体培养西葫芦子叶花芽分化最佳龄期的选择

为研究花芽分化的机理，选择西葫芦种苗在一定真叶期时的子叶为外植体，培养于附加KT1.0mg/L MS培养基中，其花芽分化率可达60%；分析葫芦种苗在一片真叶期时子叶内源激素和多胺含量，发现子叶内源GA1/3含量偏低，而ZRs含量剧增，同时ZRs/GA1/3、ABA/GA1/3、Spd/Put、Spm/Put比值较高，这些内源因素有利于西葫芦子叶花芽分化。     

植物生长调节剂对石竹试管成花及内源激素与多胺的影响

以无根石竹试管苗为试材，用植物生物调节剂调控石竹试管成花，同时测定了成花过程中内源激素与多胺的变化。结果表明，低浓度NAA有利于成花，0.2mg/L的NAA可将成花率由对照的33.3％提高到71.7％；6-BA抑制成花，浓度为0.5mg/L时便完全抑制成花。在成花过程中，iPAs，ZRs，IAA，Spd含量出现峰值，且含量的增加有利于成花。IAA/(iPAs ZRs)的比值影响石竹试管苗的发育，当这一比值较低时，石竹便一直处于营养生长状态。     

聚胺抑制剂DEG对水基钻井液抑制性的影响

端羟基改性聚醚胺DEG是一种新型页岩抑制剂。与氯化钾、甲酸钠等抑制剂盐相比,DEG对淡水钻井液和盐水钻井液的流变性及滤失性影响相对较小。对钠基膨润土的线性膨胀倍数降低率以及对新疆塔里木油田侏罗系页岩岩屑的热滚回收率实验表明,DEG具有更优的抑制性,其1%加量的抑制性等效于10%氯化钾。在经历36%氯化钠、5%无水氯化钙或5%结晶氯化镁分别在120℃下热滚16 h污染后,流变性能较为稳定。在100~150℃高温滚动老化16 h后,其流变性变化亦很小。证实DEG是一种抑制性能优异、对钻井液性能影响较小、且有一定抗温、抗盐能力的新型泥页岩抑制剂,有望用于深井、复杂地层和海洋钻探。     

Antizyme and antizyme inhibitor, a regulatory tango

The polyamines are small basic molecules essential for cellular proliferation and viability. An autoregulatory circuit that responds to the intracellular level of polyamines regulates their production. In the center of this circuit is a family of small proteins termed antizymes. Antizymes are themselves regulated at the translational level by the level of polyamines. Antizymes bind ornithine decarboxylase (ODC) subunits and target them to ubiquitin-independent degradation by the 26S proteasome. In addition, antizymes inhibit polyamine transport across the plasma membrane via an as yet unresolved mechanism. Antizymes may also interact with and target degradation of other growth-regulating proteins. An inactive ODC-related protein termed antizyme inhibitor regulates polyamine metabolism by negating antizyme functions. The ability of antizymes to degrade ODC, inhibit polyamine uptake and consequently suppress cellular proliferation suggests that they act as tumor suppressors, while the ability of antizyme inhibitors to negate antizyme function indicates their growth-promoting and oncogenic potential.     

正常与退败竹笋内同功酶谱变化的研究

毛竹竹笋在不同的生长期呈现不同的过氧化物酶同功酶谱。竹笋尖端处于旺盛的有丝分裂时，其过氧化物酶同功酶谱带多而色深。随竹笋的生长和节间的伸长，节间上部的细胞先停止分裂，居间分生组织随之逐渐缩小而只限于节间下部，同功酶谱也表现相应的酶谱变化，并出现一条色深带宽的特殊酶带（Ｃ０）。在竹笋退败过程中，竹笋尖端的过氧化物酶同功酶的活性减弱，多胺含量减少，同时也出现一条特殊Ｃ０酶带。     

A simplified method for isocratic HPLC analysis of polyamines

Summary A simple technique is described for the separation and analysis of polyamines in tissues and body fluids, utilizing precolumn clean-up on disposable CM-cellulose columns, followed by an automatable HPLC procedure. Complete separation and analysis takes 12–15 min per sample with sensitivity in the pmole range.Acknowledgments. Supported by USPHS HD-09713, EPA R811621010 and by Research Scientist Development Award DA-00006 to TAS.     

Regional pattern and heat-resistance of brain 5′-deoxy-5′-methylthioadenosine phosphorylase

Summary The distribution of 5-deoxy-5-methylthioadenosine (MTA) phosphorylase in 10 pig brain areas was determined. The observed regional differences of the enzymatic activity seem to reflect more the pattern of brain spermine distribution rather than that of spermidine. Moreover, comparative studies on the heat-resistance of MTA phosphorylase extracted from the whole brain of various species suggest structural differences in the enzyme molecules occurring in the brains of different animals.     

多胺代谢对石竹试管苗成花中内源激素含量的影响

以无根石竹试管苗为试材，通过外施多胺及多胺生物合成抑制剂调控石竹(Dianthus chinensis L.)试管苗成花，研究成花过程中石竹内源激素含量的变化。结果表明，外源腐胺(Put)、亚精胺(Spd)、精胺(Spm)及多胺生物合成抑制剂二氟甲基鸟氨酸(DFMO)、二氟甲基精氨酸(DFMA)、环己胺硫酸盐(CHAS)能调控石竹试管苗成花率；Spm、Spd分别将成花率由38.3％提高至48．3％和60．0％，也提高了内源玉米素核苷类(ZRs)、异戊烯腺嘌呤类(iPAs)、吲哚-3-乙酸(IAA)水平；DFMO、CHAS则完全抑制成花，显降低内源IAA水平。因此，内源激素与多胺的代谢水平共同控制石竹试管苗成花。