Cloning and characterization of interferon stimulated genes Viperin and ISG15, and their promoters from snakehead Channa argus

By suppression subtractive hybridization, rapid amplification of cDNA ends and gene walking methods, interferon stimulated genes (ISGs), Viperin and ISG15, and their promoters have been cloned and characterized from snakehead Channa argus. The Viperin cDNA was found to be 1474 nt and contain an open reading frame (ORF) of 1059 nt that translates into a putative peptide of 352 amino acid (aa). The putative peptide of Viperin shows high identity to that in teleosts and mammals except for the N-terminal 70 aa. The ISG15 cDNA was found to be 758 nt and contain an ORF of 468 nt that translates into a putative peptide of 155 aa. The putative peptide of ISG15 is composed of two tandem repeats of ubiquitin-like (UBL) domains, and a canonical conjugation motif (LRGG) at C-terminal. Viperin and ISG15 promoter regions were characterized by the presence of interferon stimulating response elements (ISRE) and gamma-IFN activation sites (GAS). ISRE is a feature of IFN-induced gene promoter and partially overlaps interferon regulatory factor (IRF) 1 and IRF2 recognition sites. GAS is responsible for the gamma-IFN mediated transcription. One conserved site for NF-kappa B was found in the promoter region of Viperin. This is the first report of conservative binding motif for NF-kappa B in accordance with the consensus sequence (GGGRN-NYYCC) among teleost ISG promoters. Moreover, there were also TATA, CAAT and Sp1 transcription factor sites in Viperin and ISG15 promoters. In 5' untranslated region (UTR), snakehead ISG15 gene contains a single intron, which differs from Viperin gene. The transcripts of Vipeirn and ISG15 mRNA were mainly expressed in head kidney, posterior kidney, spleen and gill. The expression levels in liver were found to increase obviously in response to induction by IFN-inducer poly I : C.

TRAIL in the mandarin fish Siniperca chuatsi: Gene and its apoptotic effect in HeLa cells

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is one of the TNF superfamily members, participating in many biological processes including cell proliferation and apoptotic death. In this study, a TRAIL gene was cloned from a perciform fish, the mandarin fish Siniperca chuatsi, a major cultured fish in China's aquaculture, and is named as SCTRAIL for S. chuatsi TRAIL. The full-length cDNA of SCTRAIL is 1359 bp, encoding a 283-amino-acid protein. This deduced protein contains the CYS231, a 23-mer fragment of transmembrane region, a glycosylation site and a TNF family signature, all of which are conserved among TRAIL members. SCTRAIL gene consists of six exons, with five intervening introns, spaced over approximately 9 kb of genomic sequence. Southern blotting demonstrated that the SCTRAIL gene is present as a single copy in mandarin fish genome. A 620 bp promoter region obtained by genome walking contains a number of putative transcription factor binding sites, such as Oct-1, Sp-1, NF-1, RAP-1, C/EBPaLp, NF-kappa B and AP-1. The SCTRAIL is constitutively expressed in all the analyzed tissues, as revealed by RT-PCR, which is confirmed by Western blotting analysis using polyclonal antibody against bacteria-derived recombinant SCTRAIL protein. As an apoptosis-inducing ligand, the overexpression of SCTRAIL but not the mutant SCTRAIL-C203S in HeLa cells induced changes characteristic of apoptosis, including chromatin condensation, nucleus fragmentation, DNA ladder, and increase of sub-G0/G1 cells in FACS analysis. (c) 2007 Elsevier Ltd. All rights reserved.

Mitochondrion-mediated apoptosis induced by Rana grylio virus infection in fish cells

A fish cell line, fathead minnow (FHM) cell, was used to investigate the alteration of mitochondrial dynamics and the mechanism of apoptosis under Rana grylio virus (RGV) infection. Microscopy observations, flow-cytometry analysis and molecular marker detection revealed the apoptotic fate of the RGV-infected cells. Some typical apoptotic characteristics, such as chromatin condensation, DNA fragmentation and mitochondrial fragmentation, were observed, and significantly morphological changes of mitochondria, including size, shape, internal structure and distribution, were revealed. The mitochondria in RGV-infected cells were aggregated around the viromatrix, and the aggregation could be blocked by colchicine. Moreover, the Delta psi m collapse was induced, and caspase-9 and caspase-3 were activated in the RGV-infected cells. In addition, NF-kappa B activation and intracellular Ca2+ increase were also detected at different times after infection. The data revealed the detailed dynamics of mitochondrion-mediated apoptosis induced by an iridovirus, and provided the first report on mitochondrial fragmentation during virus-induced apoptosis in fish cells.

Androgen receptor targets NFKB and TSPI to suppress prostate tumor growth in vivo

The androgen role in the maintenance of prostate epithelium is subject to conflicting opinions. While androgen ablation drives the regression of normal and cancerous prostate, testosterone may cause both proliferation and apoptosis. Several investigators note decreased proliferation and stronger response to chemotherapy of the prostate cancer cells stably expressing androgen receptor (AR), however no mechanistic explanation was offered. In this paper we demonstrate in vivo anti-tumor effect of the AR on prostate cancer growth and identify its molecular mediators. We analyzed the effect of AR on the tumorigenicity of prostate cancer cells. Unexpectedly, the AR-expressing cells formed tumors in male mice at a much lower rate than the AR-negative controls. Moreover, the AR-expressing tumors showed decreased vascularity and massive apoptosis. AR expression lowered the angiogenic potential of cancer cells, by increasing secretion of an anti-angiogenic protein, thrombospondin-1. AR activation caused a decrease in RelA, a subunit of the pro-survival transcription factor NF kappa B, reduced its nuclear localization and transcriptional activity. This, in turn, diminished the expression of its anti-apoptotic targets, Bcl-2 and IL-6. Increased apoptosis within AR-expressing tumors was likely due to the NF kappa B suppression, since it was restricted to the cells lacking nuclear (active) NF kappa B. Thus we for the first time identified combined decrease of NF kappa B and increased TSP1 as molecular events underlying the AR anti-tumor activity in vivo. Our data indicate that intermittent androgen ablation is preferable to continuous withdrawal, a standard treatment for early-stage prostate cancer. (C) 2007 Wiley-Liss, Inc.

The acute effects of microcystin LR on the transcription of nine glutathione S-transferase genes in common carp Cyprinus carpio L.

The glutathione S-transferases play important roles in the detoxification of microcystin. In this experiment, nine glutathione S-transferase genes including cytosolic GSTs (rho, mu, theta, alpha and pi), mitochondrial GST (kappa) and microsomal GSTs (mGST1, mGST2 and mGST3) were cloned from common carp Cyprinus carpio. The mRNA abundance of each carp GST isoform in liver was analyzed by real time PCR. The relative changes after stimulation with microcystin LR were also analyzed: increased levels of transcription of GST alpha, rho and mGST3 isoforms were detected at 6 h post stimulation; the transcription of mu, theta and mGST2 isoforms were relatively stable; and all the GST isoforms except GST kappa and rho recovered to original levels compared with controls at 72 h. It is suggested that MC-LR showed different effects on the transcription of nine carp GST isoforms. (c) 2006 Elsevier B.V. All rights reserved.

Molecular cloning of TRAF2 binding protein gene and its promoter region from the grass carp Ctenopharyngodon idellus

A tumor necrosis factor receptor-associated factor 2 binding protein (T2BP) gene was isolated from the grass carp (Ctenopharyngodon idellus) by utilizing suppression subtractive hybridization (SSH) and rapid amplification of cDNA ends (RACE). The grass carp T2BP (GT2BP) gene contains an open reading frame of 579 nucleotide(s) (nt), encoding 193 amino acids, with 23 nt 5'-untranslated region and a long 3'-untranslated region of 434 nt including poly (A), 1 AUUUA motif and 4 AUUUUA motifs. No signal peptide has been detected in the predicted GT2BP, but a characteristic forkhead associated domain is present. The GT2BP mRNA shares 83% identity with the zebrafish DNA sequence, and they both have no introns in the genomic DNA. The putative transcription factor binding sites of GT2BP include two C/EBP alpha binding sites, and one c-Jun binding, one AP-1 binding, and one nuclear factor kappa B (NF kappa B) binding sites. Southern blot analysis revealed that the GT2BP was a single-copy gene. Individual difference was observed in GT2BP expression in examined organs of healthy grass carp. However, the expression of GT2BP in all examined organs in a fish with the highest copepod infection level and the significantly higher expression level in spleen and liver in infected fish may indicate its up-regulation with the parasite infection. (c) 2005 Elsevier B.V. All rights reserved.

Characterization of cDNA encoding immunoglobulin light chain of the Mandarin fish (Siniperca chuatsi)

Immunoglobulin light chain cDNA sequences of a perciform fish, the mandarin fish Siniperca chuatsi were amplified from head kidney mRNA by reverse transcription (RT)-PCR and RACE methods using degenerated primer and gene specific ones. In cDNA sequences of the VL region, nucleotide exchanges were present mainly within CDRs, although a lesser degree of variability was also found in FRs. Moreover, the length of CDRI and CDR3 in the mandarin fish is shorter than in most other fish species. In the middle of S. chuatsi CL region, a microsatellite sequence (AGC)(6-8) was found, which is also present in another perciform species, the spotted wolffish (Anarhichas minor). The comparison of amino acid sequence of the mandarin fish CL domain with those of other vertebrates showed the highest degree of similarity of 94.5% to the spotted wolffish, while the similarity with rainbow trout (Oncorhynchus mykiss) Ig L1 (62.7%) and channel catfish (Ictalurus punctatus) Ig LG (55.9%) isotypes is also higher. However, there is only 50% identity in the VL regions between the mandarin fish and the wolffish. The sequence similarity of the mandarin fish CL domain with those of higher vertebrate did not readily allow it to be classified as kappa or lambda isotype. The phylogenetic analyses also demonstrated that the CL genes of the mandarin fish and most other teleost fish cluster as a separate branch out of the mammal kappa and lambda branches. (C) 2003 Elsevier B.V. All rights reserved.

Two-dimensional simulation of high-order laterally-coupled GaAs-AlGaAs DFB laser diodes

Laterally-coupled distributed feedback (LC-DFB) laser diodes made without an epitaxial re-growth process have the advantage of a simple fabrication process. In this paper, two-dimensional optical field distribution of the fundamental quasi TE (transverse electric) mode is calculated by means of a semivectorial finite-difference method (SV-FDM). The dependence of the effective coupling coefficient (kappa(eff)) on the dutycycle of first-, second- and third-order LC-DFB LDs is investigated using modified coupled wave equations.

Effect of metal contact's reflection on the effective coupling coefficient of second-order DFB laser diodes

For a second-order DFB-LD, the presence of a metal contact layer can reduce I-st-order radiation. Part of the reflected power is redistributed into guided modes and results in a variation of the effective coupling coefficient kappa(eff). In this paper, we study the effect of the Au top contact's reflection on the kappa(eff) of 2(nd)-order DFB lasers. (C) 2004 Wiley Periodicals, Inc.

Determination of the absorption for incident light propagating parallel through the guest-host polymer film waveguide

Guest host polymer thin films of polymethyl methacrylate (PMMA) incorporated with (4'-nitrobenzene)-3-azo-9-ethylcarbazole (NAEC) were fabricated by spin coating and then poled by the method of corona-onset poling at elevated temperature. The absorption mechanism of the polymeric film, which is very important for the optical transmission losses and directly relates to the orientation of chromophore NAEC in polymer PMMA, was investigated in detail. From the UV-visible absorption spectra for NAEC/PMMA film before and after being poled, we determined the change of absorption coefficient kappa with the wavelength and approximately calculated the maximum absorption A(parallel tomax) as 3.46 for incident light propagating parallel through the film, i.e. the ordinary polarized light, which cannot be directly measured in the spectro photometer. (C) 2002 Elsevier Science Ltd. All rights reserved.

Strain effects on optical polarisation properties in (11(2)over-bar2) plane GaN films

We present the theoretical results of the electronic band structure of wurtzite GaN films under biaxial strains in the (11 (2) over bar2)-plane The calculations are performed by the kappa p perturbation theory approach through using the effective-mass Hamiltonian for an arbitrary direction The results show that the transition energies decrease with the biaxial strains changing from -0 5% to 0 5% For films of (11 (2) over bar2)-plane, the strains are expected to be anisotropic in the growth plane Such anisotropic strains give rise to valence band mixing which results in dramatic change in optical polarisation property The strain can also result in optical polarisation switching phenomena Finally, we discuss the applications of these properties to the (11 (2) over bar2) plane GaN based light emitting diode and lase diode

沈阳市城市扩展分析与模拟研究

城市扩展及其导致的土地利用/土地覆被变化作为全球环境变化的重要驱动因素，日益引起社会各界的普遍关注。新中国成立以来，沈阳市经历了快速的城市化过程，特别是进入21世纪以来，伴随着人口增长和经济发展，中心城区持续向外扩张，导致基本农田大量流失，区域景观和生态环境质量日益下降，给沈阳市的城市增长管理和可持续发展带来严峻挑战。 利用遥感(RS)、地理信息系统(GIS)和空间Logistic回归模型对1988-2004年间沈阳市的城市扩展与土地利用变化特征及其驱动力进行深入分析，并在此基础上利用基于细胞自动机(CA)的城市扩展模型－SLEUTH对历史时期(1988-2004年)的城市扩展格局进行模拟与重建，对未来(2005-2030年)不同发展条件下的城市扩展进行模拟与环境影响评估，以期为城市增长管理与区域可持续发展提供决策支持。本论文取得如下研究成果： (1) 1988-2004年间，沈阳市辖区城市面积持续增加，城市扩展强度逐渐增强；2000-2004年城市扩展规模和强度都达到最大；沈阳市城市化进程正在显著加速。城市扩展具有明显的空间分异特征：整个研究时段内，市区西南方向是城市扩展的主方向，中心城区周边(8~10km)及各级经济开发区是扩展的热点区域。 (2) 1988-2004年间，沈阳市辖区土地利用变化最主要的特征是耕地向城乡建设用地的大面积转换。持续的城市扩展导致区域景观日益破碎化和复杂化。城市和其它建设用地的景观影响日益增强，耕地的优势地位减弱，且破碎化程度增加，斑块形状日趋复杂。城市化空间梯度上的土地利用格局变化分析表明，随着城市化水平的提高，景观组成和空间配置发生了明显变化。处在城市化前沿区域的城郊地区，景观格局表现出景观多样性增加、破碎化程度加深和形状日趋复杂等特点。 (3) 1988-2004年间，沈阳市辖区城市扩展主要受到社会经济发展的推动作用和政策因素的激励与导向作用。空间Logistic回归分析显示，开发区建设与行政建制变化、道路与城镇分布、浑河和城市规划是城市空间扩展的主要影响因素。 (4) ROC曲线统计、Kappa统计与多分辨率误差估算以及景观指数从城市扩展总体预测能力、增长数量、空间位置和空间格局上给予SLEUTH模型一个全面、客观的评估。总体上来说，SLEUTH模型具有可信精度，较好地表达了沈阳市1988-2004年间城市扩展的总体趋势，对城市扩展面积的拟合精度很高。但是，与其它城市扩展模型相似，在像元尺度上对城市扩展空间位置的预测和对城市空间格局的表达还有待于提高；随着分辨率的降低，模型对城市发展中空间邻域关系的表达效果趋于提高。SLEUTH模型对城市扩展的总体模拟精度要高于空间Logistic回归模型，但是对城市扩展位置的模拟准确性低于后者。 (5) 通过分析发现，影响SLEUTH模拟准确性的主要因素包括模型结构、地方城市发展特征、模型应用的时空尺度和模型输入数据的获取与误差传递等。通过修改模型组分设置、开展模型敏感性与不确定性分析以及实行城市扩展一体化模拟可以提高SLEUTH模型的模拟效力，而具体实现方法需要深入研究。基于模型评估结果和效力提高的对策，对城市扩展演变的时空格局进行了较为准确的重建，为其相关研究提供了可靠的历史数据资料。 (6) 遵循沈阳市目前和未来的区域开发政策、最新修编的城市总体规划，以及社会对区域生态环境保护的要求，设计了五个城市发展预案，即目前趋势发展预案(CT)、区域开发政策与城市规划预案(PP)、生态可持续发展预案(ES)、紧凑式发展格局预案(CD)和特定增量发展预案(GA)。对不同预案条件下未来(2004-2030年)城市扩展面积和空间格局、城市扩展热点区域、城市景观格局变化及其景观生态效应，以及对其它类型土地资源的消耗四个方面进行了分析和比较，为沈阳市城市规划、生态建设以及可持续增长管理提供了许多有价值的决策信息。

岷江上游地区景观格局与生态承载力变化及预测研究

岷江上游是我国十分典型的山地生态脆弱区。该地区的生态环境意义十分重大，既是长江上游生态屏障的重要组成部分，更是成都平原的重要生态屏障和水源生命线，其生态环境状况直接影响成都平原水资源的质量和数量，以至影响到整个岷江流域甚至整个长江上游的生态环境与社会经济发展。本论文通过3S技术手段，应用转移矩阵、景观指数和Kappa指数系列方法对岷江上游的景观变化从1974到2000年进行了综合分析，同时应用CLUE-S模型在有无“天然林保护工程”两个预案下对该区域2001到2020年的景观变化进行了预测。然后，应用基于能值理论进行改进的生态足迹方法和传统生态足迹方法对岷江上游地区的1982到2000的生态承载力进行了分析，以反映研究区的生态环境质量和可持续发展情况；应用多元统计方法和CLUE-S模型预测的结果预测了研究区2001到2020年的生态足迹和生态承载力。对岷江上游地区的景观格局和生态承载力的变化进行分析和预测得到如下主要结论： 1. 岷江上游地区景观在1974到2000年间格局变化并不十分显著，景观由少数几种景观类型所控制，各景观类型有不断趋于平均化的趋势，但速度缓慢，景观的破碎化程度越来越严重。研究区的景观变化以有林地的不断减少和其它景观类型的相应增加为特点，主要的景观变化发生在有林地、灌木林地、草地、耕地和经济林地之间。此时间段内的景观林地的面积不断减少，大部分转化为灌木林地和草地，使得其面积相应增加。耕地和经济林地面积不断增长，增长速度最为迅速。 2. 在有无“天然林保护工程”两种预案下，有林地向着不同的方向发展，有林地变化情况的不同导致其它景观类型的变化不同。在“无天保”预案下，林地面积不断减少，灌木林地、草地和耕地面积不断增长，景观的破碎化程度不断加剧，斑块形状更加不规划，景观的连通性不断下降。在“天保”预案下，林地面积有增长趋势，灌木林地和草地面积有所下降，耕地面积有下降趋势，景观的破碎化程度有减小的趋势，景观形状变得更加规则，景观的连通性也将得到改善。由此，“天然林保护工程”对景观格局未来变化有着决定性的作用。 3. 岷江上游地区的生态足迹从1982到2000年间呈缓慢的上升趋势，表明研究区内居民的生活水平不断提高，但速度缓慢。虽然研究区在研究时期内的生态承载力大于需求，但生态承载力呈明显的下降趋势，造成这种情况的主要原因是由于资源的不合理利用方式造成的，特别是对森林的过度采伐。连续的木材采伐给岷江上游地区脆弱的生态系统带来严重后果，导致了林地面积减小、森林质量下降、水土流失加剧和泥石流频繁发生。 4. 对于生态足迹和生态承载力在两个预案的预测表明到2020年为止岷江上游地区仍为可持续发展状态。在“无天保”预案下，生态承载力不断下降，生活足迹不断上升，研究区向不可持续的方向发展；在“天保”预案下，生态承载力在2003年后开始逐渐上升，同时，由于木材采伐被禁止，导致岷江上游地区的生态足迹大为下降，研究区将向更加可持续的方向发展。由两种预案的结果对比可以发现1998年开始实施的“天然林保护工程”能够扭转岷江上游地区未来的生态承载力变化方向。生态承载力可以反映生态系统的质量，说明该政策的实施可以有效改善岷江上游地区未来的生态系统。 5. 传统生态足迹方法应用的生物生产能力数据为常量，所以它能够有效地比较不同年份和不同区域间消费数据的变化情况。实际土地需求法应用的生物生产能力和均衡因子均根据研究区实际数据计算得到，其反映研究区的实际情况更为有效。应用能值对生态足迹方法进行改进，改变了传统生态足迹以生物圈为限制的不足。本文改进的方法－区域能值足迹法能够有效地反映研究区的实际情况，同时又能够将科技进步所带来的影响加以考虑。

辽宁沿海经济带景观格局动态预测及其生态安全研究

21世纪中国将进入工业化与城市化快速发展阶段，随着经济全球化与竞争国际化，产业集群开始成为经济发展的主流，以临港产业为代表的沿海经济带开发建设已成为发达国家的重要经验和国内沿海省市的主导区域战略，辽宁沿海经济带的开发建设将进一步加大沿海地区与周边地区及内地的资源信息交换，人口的大量流入、城市化进程的加快等都可能对沿海区域的生态环境质量和可持续发展与生态安全产生重要影响。 论文通过3S技术手段，应用转移矩阵、土地利用度量公式、景观空间格局分析和Kappa 指数系列方法对1988～2007 年辽宁沿海经济带的景观变化进行了综合分析，同时应用CLUE-S 模型在有无“辽宁沿海经济带开发建设规划”两个预案下对该区域2008～2020 年的景观变化进行了预测。应用生态足迹理论与方法对研究区1990～2006年的生态足迹与生态承载力进行了分析，以反映研究区可持续发展情况；应用时间序列（ARMA）与支持向量机（SVM）预测了研究区2007～2020年生态足迹与生态承载力变化。并对研究区进行了基于生态足迹的区域生态安全动态分析及预测研究，最后提出了研究区生态安全对策，得到如下主要结论： （1）辽宁沿海经济带在1988～2007年间景观格局变化并不十分显著，景观由少数几种景观类型所控制，各景观类型有不断趋于平均化的趋势，但速度较慢，景观的破碎化程度越来越严重。土地利用度逐步增大，反映在景观变化上，是以建设用地的持续扩张与耕地以及林地、水域面积缩小为特点，其中建设用地在景观类型转换中发挥着越来越重要的作用。主要的景观变化发生在耕地、林地、水域与建设用地之间。 （2）在有无“规划”两种预案下，景观变化的趋势基本一致，但变化幅度有明显差别。两种预案下耕地都趋于减少，但“规划预案”降幅更大一些。建设用地逐渐增加，但“规划预案”扩张更快，面积更多。建筑用地变化情况的不同导致其它景观类型变化的不同。两种预案下景观的破碎化程度均有减小的趋势，斑块形状趋于规则，景观的连通性也在逐年增大，其中在“规划预案”中表现得更为显著。 （3）辽宁沿海经济带从1990～2006年间的人均生态足迹与生态承载力均呈逐渐增大趋势，且生态足迹需求明显大于生态承载力，生态赤字在逐渐增大，研究区内的生态负荷已超过了其生态容量，现有的区域发展模式是不可持续的。其中生态足迹需求增大主要来自能源足迹需求增大，而生态承载力的增加主要是因为水域类面积的增加。17年间研究区的人均万元GDP生态足迹均有不同程度的下降趋势，表明该区域的资源利用效率在逐渐提高。 （4）过去17年来，辽宁沿海经济带的生态压力指数变化趋势为先升后降，区域生态安全经历了生态较安全、稍不安全、较不安全和稍不安全等阶段，表明该区域生态安全正在逐步改善。生态占用指数与生态经济协调指数均呈逐步增大的趋势，表明研究区的社会经济发展程度和人民消费水平正在走向较富裕阶段，该区域社会经济发展与生态环境的协调性也在逐渐改善。 （5）两种预案下，辽宁沿海经济带未来14年的人均生态足迹与人均生态承载力均有逐渐增大的趋势，且人均生态足迹均超过了其人均生态承载力，存在不同程度的生态赤字，发展模式仍将是不可持续的，其中“规划预案”下的发展模式更加不可持续。 （6）两种预案下，研究区未来14年的生态安全均处于稍不安全状态，其中“规划预案”的生态压力更小一些。两种预案下研究区的生态占用指数和生态经济协调指数均有逐年增大的趋势，区域经济均将从较富裕阶段走向很富裕阶段，经济增长与生态环境的协调程度也由较好阶段步入很好阶段。其中“规划预案”下的区域经济增长更快，与生态环境的协调性将更好一些。 （7）三种方案可以降低研究区“规划预案”下的生态压力指数，实现区域的生态安全。其中同时提高研究区的生态承载力，降低生态足迹的方案更为合理可行，既保障了区域安全，又实现了区域的可持续发展目标。 （8）要保障研究区未来14年的生态安全，建议规划增加水域面积，推进区域热电联产，发展清洁能源并推动区域间资源互补共享。

东北多年冻土对气候变化的响应

近地表面多年冻土对寒区生态系统的植被覆盖、水文条件、土地利用和工程建设具有重要影响，随着气候变化研究的广泛开展，区域冻土环境的变化也成为学者关心的重要议题。中国东北的多年冻土处于欧亚大陆多年冻土带的南缘，多年冻土不如以北地区发育，是十分脆弱的多年冻土。然而，多年冻土在东北寒区生态系统中却起着重要的作用。若东北多年冻土发生退缩，则有可能加速落叶松北移和湿地退缩的过程，也会对C的释放产生重要影响。因而探明现实气候条件下东北区域多年冻土的影响因子和发育状况以及未来气候条件下多年冻土的退缩趋势，将有助于促进东北寒区生态系统的冻土和其它学科研究，同时也可为寒区开发建设提供有意义的参考。 本研究从分析东北多年冻土的主要影响因子——气候、地形和土壤条件等入手，准确地掌握了多年冻土的发育状况，并以此为根据进行了景观尺度上多年冻土分布信息的提取和融深信息的研究。同时，在区域尺度上对多年冻土的现实分布和未来气候条件下多年冻土的可能分布状况进行了探讨。最终得到以下重要结论： （1）冻结数对东北多年冻土分布具有重要的指示作用 冻结数模型具有明确的物理意义，可以指示多年冻土的发生状况。研究中，利用地形、纬度等因子，结合气温和降水数据模拟了现实气候条件下东北地区的冻结数值；并依据冻结数模型的区划标准对东北多年冻土进行分区。结果表明，冻结数在指示多年冻土分布时具有重要作用。 （2）土壤含水量、地形坡度和群落因子对多年冻土具有重要影响 以大兴安岭呼中国家级自然保护区为例，调查了该区多年冻土活动层厚度，并利用多重对比分析和相关分析的统计方法，对多年冻土活动层的影响因子进行了分析。结果表明，多年冻土活动层厚度与多个环境因子之间存在着复杂的关系。其中，土壤表层含水量与活动层厚度具有极显著的负相关关系（P<0.001），其相关系数在0.90以上，说明含水量越高，活动层厚度越浅。地形坡度和活动层厚度的相关性也达到显著水平（相关系数为0.321，P=0.006），表明坡度越陡，活动层厚度越大。几乎每个样带的海拔与活动层厚度都有显著的相关性，但在整体研究区域内海拔与活动层厚度不存在相关性。这说明活动层厚度的变异仅在本研究的样带尺度上具有规律性，而在稍大尺度上这种规律性就消失了。对于不同的群落活动层厚度的多重对比分析表明，群落的差异对活动层厚度也有明显的影响，其中狭叶杜香-泥炭藓群落（Larix gmelini-Ledum palustre var. anqustum-sphagnum magellanicum）更有利于多年冻土的保存。 （3）景观尺度上的多年冻土分布状况 在景观尺度上，以呼中国家级自然保护区为研究区，应用神经网络方法，同时以土地覆盖、等效纬度、坡向和土壤湿度多种影响因子为数据源，对多年冻土分布信息进行提取。结果表明，考虑土地覆盖、等效纬度和土壤湿度的数据源组合可以获得高精度最高的多年冻土分布信息，分类精度可以达到89.0%，多年冻土面积占研究区面积百分比达到46.71%，为780.1 km2。 （4）景观尺度上多年冻土的融深状况 研究考虑了包括植被和等效纬度两个影响活动层厚度的重要因子，并将Stefan公式进行变形，简化为包含热量条件的等效纬度因子和植被条件的C因子的函数关系。最后应用该函数关系模拟了呼中自然保护区活动层厚度空间分布，模拟结果的精度为87.25%。在模拟结果中，面积和所占比例最大的活动层厚度为70-80 cm间的活动层厚度，所占面积达到341.4 km2 ，占整个研究区面积的20.43%。而面积最小的活动层厚度为30-40 cm间的活动层厚度，面积为0.02 km2 。通过群落与活动层厚度的空间分布对比发现，呼中自然保护区占最大比例的活动层（70-80 cm）所对应的植物群落主要为落叶松-丛桦-笃斯-藓类群落（Larix gmelini-Betula ovalifolia-Vaccini uliginosum-moss）。说明呼中自然保护区冻土湿地植被主要以该群落类型为主，演替处于中间阶段。 （5）区域尺度上多年冻土的分布状况 利用证据权重法，以可能影响多年冻土分布的气候、地形和土壤等因子作为数据源，对研究区在现实气候条件下的多年冻土分布进行预测，获得了多年冻土在现实气候条件下的分布概率等信息。结果表明，当分布概率大于0.17时，划分出的多年冻土的精度最高，为78.71 %。此时，多年冻土面积为2.03×104 km2 ，约占研究区总面积的1.76%。 （6）东北多年冻土分布对气候变化的响应 利用空间代时间的方法和Kappa指数，对证据权重法在预测未来气候变化条件下多年冻土分布的准确性进行了验证，结果表明，证据权重法预测气候变化条件下多年冻土的分布状况是可行的。 在CGCM3模拟的三种气候模式下，多年冻土在2050年和2100年都将发生明显的退缩。2050年，SRES A1、SRES A2和SRES B1三种气候情景下多年冻土的面积分别为786.38 km2，705.94 km2和1 028.81 km2。与现实气候下多年冻土的面积2.03×104 km2相比，多年冻土分别退缩了96.13%，96.53%和94.94%。而2100年的模拟结果表明，三种气候情景模式下，多年冻土已经全部退化。 （7）气候变化条件下东北多年冻土的分区变化 研究将冻结数等值图与2000年中国东北冻土分区图进行叠加，计算了不同多年冻土亚区的边界对应的冻结数值，建立了利用冻结数进行中国东北多年冻土分区的标准。根据冻结数指标确定的新的中国东北冻土分区与原中国东北冻土分区进行Kappa指数认证。结果表明，冻结数分区标准更适用于中国东北多年冻土的区划。 利用新的冻结数分区标准对CGCM3模拟的三种气候情景模式下的气候变化数据进行区划表明，三种气候模式下东北多年冻土区在21世纪都会有非常明显的退缩。2050年时冻土区缩减了37.7%-42.6%，2100年时缩减了62.5%-74.0%。同时，研究结果显示，东北多年冻土区域的退缩不仅发生在多年冻土区的南界，同时多年冻土的中心退缩也较为明显，即大片连续多年冻土亚区和大片连续—岛状多年冻土亚区的退缩最为剧烈。2050年时，三种气候情景下，大片连续多年冻土亚区将退缩88.8%以上；2100年时，SRES A2模式下，大片连续多年冻土亚区将完全消失。