Mutations in RECQL4 cause a subset of cases of Rothmund-Thomson syndrome.

Rothmund-Thomson syndrome (RTS; also known as poikiloderma congenitale) is a rare, autosomal recessive genetic disorder characterized by abnormalities in skin and skeleton, juvenile cataracts, premature ageing and a predisposition to neoplasia. Cytogenetic studies indicate that cells from affected patients show genomic instability often associated with chromosomal rearrangements causing an acquired somatic mosaicism. The gene(s) responsible for RTS remains unknown. The genes responsible for Werner and Bloom syndromes (WRN and BLM, respectively) have been identified as homologues of Escherichia coli RecQ, which encodes a DNA helicase that unwinds double-stranded DNA into single-stranded DNAs. Other eukaryotic homologues thus far identified are human RECQL, Saccharomyces cerevisiae SGS1 and Schizosaccharomyces pombe rqh1. We recently cloned two new human helicase genes, RECQL4 at 8q24.3 and RECQL5 at 17q25, which encode members of the RecQ helicase family. Here, we report that three RTS patients carried two types of compound heterozygous mutations in RECQL4. The fact that the mutated alleles were inherited from the parents in one affected family and were not found in ethnically matched controls suggests that mutation of RECQL4 at human chromosome 8q24.3 is responsible for at least some cases of RTS.     

Isolation and characterization of biologically active lectin from Korean mistletoe, Viscum album var. Coloratum

A mistletoe lectin was isolated from water extracts of Korean mistletoe, a subspecies of Viscum album, grown on Quercus mongolica using CM-Sepharose chromatography followed by an affinity chromatography on a concanavalin A-Sepharose column. The compound proved to be a mistletoe lectin II with D-galactose and N-acetyl-D-galactosamine specificity. Matrix-assisted laser desorption time-of-flight mass spectroscopy showed it to have an average molecular mass of 62.7 kDa and to consist of two subunits of 30.6 kDa and 32.5 kDa. It was a basic protein with isoelectric points of 9.4 and 9.6 by capillary isoelectric focusing and was cytotoxic to Molt4 cell. Received 17 November 1998; received after revision 3 March 1999; accepted 3 March 1999     

Hyperthermia-induced apoptosis and the inhibition of DNA laddering by zinc supplementation and withdrawal of calcium and magnesium in suspension culture of tobacco cells

In the present paper we report examination of stereotypic hallmarks of apoptosis in heat-treated tobacco cells. Hyperthermia (44 °C, 4 h) caused apoptosis in 53.6% of cells when assayed 24 h after heat treatment. The induction of apoptosis by heat treatment was confirmed by flow cytometric assay. Cytological observations revealed condensation of the cytoplasm and nucleus, as well as nuclear collapse. DNA ladders were observed in DNA extracted from heat-treated cells, whereas DNA from control cells remained undegraded. The terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay revealed that 51.8% of the heat-treated cells (44 °C, 4 h) show positive reaction after a 24-h recovery. When cells were cultured in a medium supplemented with 0.4–5.0 mM ZnSO₄, internucleosomal DNA fragmentation induced by heat shock was completely negated. Strikingly, when cells were cultured in Ca²⁺ and/or Mg²⁺ free medium for 44 h followed by heat treatment, DNA laddering was not observed. The results suggest hyperthermia-induced apoptosis and a correlation between the regula tion of endonucleases and heat shock signal in apoptotic tobacco cells. Received 17 September 1998; received after revision 4 January 1999; accepted 4 January 1999     

材料的相变研究及其应用

Fe-C和Fe-X-C合金马氏体相变热力学的研究成果使结构钢的Ms温度能以热力学预测。建立了铜基合金及Fe-Mn-Si基合金马氏体相变热力学,为铜基和铁基形状记忆合金的成分和工艺设计提供基础。提出了含ZrO2陶瓷Ms温度的热力学计算方法,以及其母相晶粒大小影响Ms的正确表达式,对陶瓷的生产和工业应用都具有意义。修正马氏体变温相变动力学方程,显示低碳钢中影响碳扩散系数的合金元素影响残余奥氏体量,这有利于低碳马氏体组织钢的开发。GCr15轴承钢中残余奥氏体→马氏体的等温动力学研究显示：钢经淬火后,再进行等温处理以形成很少量的等温马氏体,再作回火,提高钢件的尺寸稳定性（经1000d后与淬火-回火比较,在接触疲劳寿命并不降低的条件下（达34%。研究了Ni-Ti、Cu-Zn-Al、Fe-Mn-Si基合金及ZrO2陶瓷的马氏体相变及其逆相变特征,揭示了影响这些材料形状记忆效应（SME）的一些因素,并指出了改善SME的途径,有利于这些材料的开发应用。贝氏体相变的热力学研究,观察到生长台阶,母相强化对相变影响的研究以及内耗测量结果,均显示贝氏体相变属扩散型机制。Cu-Zn-Al中加入阻碍Zn和Al扩散的合金元素可能提高形状记忆使用寿命。揭示CeO2-ZrO2中存在贝氏体相变,并与其出现脆性有关。Cu-Zn中β相有序化研究对有序化合金的应用具有实际意义。三元合金spinodal分解判据的建立,对借spinodal分解呈现高阻尼或高强度合金的开发颇具价值。由群论导出呈现晶体学可逆性的条件为形成单变体马氏体。应用孤立子于相变的形核-长大模型初见成效。     

Central IL-1 differentially regulates peripheral IL-6 and TNF synthesis

Centrally given interleukin (IL)-1 is known to induce a rapid rises in blood IL-6. To extend this and to examine the mechanism by which this occurs, the effects of intracerebroventricular (icv) injection of human recombinant IL-1β on mRNA expression of IL-6 and tumour necrosis factor (TNF) in the spleen and liver were examined in rats. Icv injection of IL-1 produced a rapid rise of the tissue mRNA levels of IL-6 and TNF in both organs, prior to and/or in parallel with an increase in their serum levels. Pretreatment with chlorisondamine, a ganglionic blocking agent, inhibited the IL-6 responses, while it had little influence on the TNF responses. The results suggest that brain IL-1 induces peripheral production of IL-6, but not of TNF, through autonomic nervous system activation. Received 27 October 1997; received after revision 15 December 1997; accepted 12 January 1998     

A new lysozyme from the eastern oyster (<Emphasis Type="Italic">Crassostrea virginica</Emphasis>) indicates adaptive evolution of <Emphasis Type="Italic">i</Emphasis>-type lysozymes

A new lysozyme (cv-lysozyme 2) with a MALDI molecular mass of 12 984.6 Da was purified from crystalline styles and digestive glands of eastern oysters (Crassostrea virginica) and its cDNA sequenced. Quantitative real time RT-PCR detected cv-lysozyme 2 gene expression primarily in digestive gland tissues, and in situ hybridization located cv-lysozyme 2 gene expression in basophil cells of digestive tubules. Cv-lysozyme 2 showed high amino acid sequence similarity to other bivalve mollusk lysozymes, including cv-lysozyme 1, a lysozyme recently purified from C. virginica plasma. Differences between cv-lysozyme 2 and cv-lysozyme 1 molecular characteristics, enzymatic properties, antibacterial activities, distribution in the oyster body and site of gene expression indicate that the main role of cv-lysozyme 2 is in digestion. While showing that a bivalve mollusk employs different lysozymes for different functions, findings in this study suggest adaptive evolution of i type lysozymes for nutrition. Received 30 August 2006; received after revision 14 October 2006; accepted 6 November 2006     

A gamma-ray burst with a high-energy spectral component inconsistent with the synchrotron shock model

Gamma-ray bursts are among the most powerful events in nature. These events release most of their energy as photons with energies in the range from 30 keV to a few MeV, with a smaller fraction of the energy radiated in radio, optical, and soft X-ray afterglows. The data are in general agreement with a relativistic shock model, where the prompt and afterglow emissions correspond to synchrotron radiation from shock-accelerated electrons. Here we report an observation of a high-energy (multi-MeV) spectral component in the burst of 17 October 1994 that is distinct from the previously observed lower-energy gamma-ray component. The flux of the high-energy component decays more slowly and its fluence is greater than the lower-energy component; it is described by a power law of differential photon number index approximately -1 up to about 200 MeV. This observation is difficult to explain with the standard synchrotron shock model, suggesting the presence of new phenomena such as a different non-thermal electron process, or the interaction of relativistic protons with photons at the source.     

华南贵东杂岩体单颗粒锆石激光探针ICPMS U-Pb定年及其成岩意义

系统的单颗粒锆石激光探针ICPMS U-Pb同位素定年表明, 贵东杂岩体是印支期~燕山期多次岩浆侵入形成的复式杂岩体, 其中鲁溪岩体(239 ± 5 Ma)、下庄岩体(235.8 ± 7.6 Ma)是印支期花岗岩; 隘子岩体(160.1 ± 6.1 Ma)、司前岩体(151 ± 11 Ma)是燕山期花岗岩. 下庄岩体中1275~2137 Ma残留锆石的发现, 表明贵东花岗岩杂岩体的物质来源与华南元古宙陆壳基底有关. 详细的单颗粒锆石激光探针ICPMS U-Pb同位素定年为研究该杂岩体的形成演化与构造作用、成矿作用的关系提供了重要的依据.     

Unscheduled CDK1 activity in G1 phase of the cell cycle triggers apoptosis in X-irradiated lymphocytic leukemia cells

Cyclin-dependent kinase 1 (CDK1) is a major component of the cell cycle progression engine. Recently, several investigations provided evidence demonstrating that unscheduled CDK1 activation may also be involved in apoptosis in cancerous cells. In this article, we demonstrate that X-ray irradiation induced G1 arrest in MOLT-4 lymphocytic leukemia cells, the arrest being accompanied by reduction in the activity of CDK2, but increased CDK1 activity and cell apoptosis in the G1 phase. Interestingly, this increase in CDK1 and apoptosis by ionizing radiation was prevented by pretreatment with the CDK1 inhibitor, roscovitine, suggesting that CDK1 kinase activity is required for radiation-induced apoptotic cell death in this model system. Furthermore, cyclin B1 and CDK1 were detected co-localizing and associating in G1 phase MOLT-4 cells, with the cellular lysates from these cells revealing a genotoxic stress-induced increase in CDK1 phosphorylation (Thr-161) and dephosphorylation (Tyr-15), as analyzed by postsorting immunoprecipitation and immunoblotting. Finally, X-irradiation was found to increase Bcl-2 phosphorylation in G1 phase cells. Taken together, these novel findings suggest that CDK1 is activated by unscheduled accumulation of cyclin B1 in G1 phase cells exposed to X-ray, and that CDK1 activation, at the wrong time and in the wrong phase, may directly or indirectly trigger a Bcl-2-dependent signaling pathway leading to apoptotic cell death in MOLT-4 cells. Received 30 March 2006; received after revision 23 June 2006; accepted 24 August 2006 J. Wu and Y. Feng contributed equally to this work.