Assessment of cattle genetic introgression into domestic yak populations using mitochondrial and microsatellite DNA markers

Hybridization between yak Poephagus grunniens and taurine Bos taurus or indicine B. indicus cattle has been widely practiced throughout the yak geographical range, and gene flow is expected to have occurred between these species. To assess the impact of cattle admixture on domestic yak, we examined 1076 domestic yak from 29 populations collected in China, Bhutan, Nepal, India, Pakistan, Kyrgyzstan, Mongolia and Russia using mitochondrial DNA and 17 autosomal microsatellite loci. A cattle diagnostic marker-based analysis reveals cattle-specific mtDNA and/or autosomal microsatellite allele introgression in 127 yak individuals from 22 populations. The mean level of cattle admixture across the populations, calculated using allelic information at 17 autosomal microsatellite loci, remains relatively low (mY(cattle) = 2.66 +/- 0.53% and Q(cattle) = 0.69 +/- 2.58%), although it varies a lot across populations as well as among individuals within population. Although the level of cattle admixture shows a clear geographical structure, with higher levels of admixture in the Qinghai-Tibetan Plateau and Mongolian and Russian regions, and lower levels in the Himalayan and Pamir Plateau region, our results indicate that the level of cattle admixture is not significantly correlated with the altitude across geographical regions as well as within geographical region. Although yak-cattle hybridization is primarily driven to produce F-1 hybrids, our results show that the subsequent gene flow between yak and cattle took place and has affected contemporary genetic make-up of domestic yak. To protect yak genetic integrity, hybridization between yak and cattle should be tightly controlled.

Mitochondrial DNA sequence polymorphisms of five ethnic populations from northern China

To study the mitochondrial DNA (mtDNA) polymorphisms in a total of 232 individuals from five ethnic populations (Daur, n=45; Ewenki, n=47; Korean, n=48; Mongolian, n=48; Oroqen, n=44) in northern China, we analyzed the control region sequences and typed for a number of characteristic mutations in coding regions (especially the region 14576-16047), by direct sequencing or restriction-fragment-length-polymorphism (RFLP) analysis. With the exception of 14 individuals belonging to the European-specific haplogroups R2, H, J, and T, the mtDNAs considered could be assigned into the East Asian-specific haplogroups described recently. The polymorphisms in cytochrome b sequence were found to be very informative for defining or supporting the haplogroups status of East Asian mtDNAs in addition to the reported regions 10171-10659 and 14055-14590 in our previous study. The haplogroup distribution frequencies varied in the five ethnic populations, but in general they all harbored a large amount of north-prevalent haplogroups, such as D, G, C, and Z, and thus were in agreement with their ethnohistory of northern origin. The two populations (Ewenki and Oroqen) with small population census also show concordant features in their matrilineal genetic structures, with lower genetic diversities observed.

Different matrilineal contributions to genetic structure of ethnic groups in the Silk Road region in China

Previous studies have shown that there were extensive genetic admixtures in the Silk Road region. In the present study, we analyzed 252 mtDNAs of five ethnic groups (Uygur, Uzbek, Kazak, Mongolian, and Hui) from Xinjiang Province, China (through which the

Effects of aniracetam on extracellular levels of transmitter amino acids in the hippocampus of the conscious gerbils: an intracranial microdialysis study

The effects of aniracetam on extracellular amino acid levels in the hippocampus of conscious gerbils, with or without transient cerebral ischemia/reperfusion, were measured by microdialysis and reverse phase-high performance liquid chromatography. Increased extracellular levels of aspartate and glutamate that were observed in the hippocampus of conscious gerbils during transient global forebrain ischemia were reversed by aniracetam. In contrast, the level of extracellular gamma-aminobutyric acid was increased, while taurine was maintained at a higher level than other amino acids by administration of aniracetam (100 mg/kg, p.o.) 60 min before ischemia. Further, in contrast to ischemic animals, administration of aniracetam (100 mg/kg, p.o.) enhanced the release of glutamate and aspartate in the normal gerbil hippocampus. The results suggest that these effects might be due to a partial calcium agonist activity of aniracetam, and that the effects of aniracetam on amino acid levels might be a mechanism of protection against delayed neuronal death in the ischemic hippocampus, thereby improving memory dysfunction induced by ischemia/reperfusion. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

国际化标准框架下蒙文操作系统的设计

蒙文操作系统实现较为复杂的原因在于两个方面：①传统蒙文采用自顶向下竖写、每列从左向右排列的书写方式；②蒙文字符在不同文本上下文中采用变化相当复杂的显现字形．基于操作系统国际化体系结构，从蒙文字符集、蒙文字符的变形显现、蒙文文本的垂直显示、蒙文独特的图形用户界面等多个方面阐述了传统蒙文操作系统实现中面临的难点和技术方案；简要介绍了基于Qt／KDE桌面系统的实现；最后提出了蒙文操作系统实现仍需要解决的问题。

在Qt上实现蒙文显示的设计与实现

随着软件产业国际化进程的发展,在操作系统中实现对我国少数民族文字的显示是一项具有挑战性和刻不容缓的任务,针对这项任务先分析了少数民族文字中蒙古文的语法特点和书写特点、桌面系统平台库QT的体系结构特点以及OpenType字体文件的特点,在此基础之上提出在QT中使用OpenType字体文件来实现蒙古文显示的详细实现方案,最后给出了目前该方案在项目中的实现情况和效果,并阐述了还有哪些地方需要进一步研究和改进。

传统蒙古文变形显示机制研究与实现

多年来蒙古文处理系统重复开发、互不兼容的根本原因就是没有统一的标准:编码标准不统一、字库标准不统一、输入法不统一。随着国际化、多语言化的发展,开发基于ISO/IEC10646和UNICODE国际编码标准、OpenType智能字体技术的不同语言文字处理系统已经成为趋势。本文阐述了一个蒙古文显示系统,它完全支持Unicode标准并使用了OpenType技术自动进行字形选型,其实现是基于QT库的,但核心实现很容易移植到Pango,ICU等其他复杂文本布局(CTL)处理项目中。

基于OpenOffice.org蒙古文办公套件的设计与实现

作为蒙古文信息处理的重要组成部分,开发符合蒙古文应用习惯的办公套件产品对于传承民族文化具有重要意义。开源项目OpenOffice.org的不断发展和日益成熟,为蒙古文办公套件的研制开发提供了有利的契机。该文讲述了以OpenOffice.org为源代码基础,实现基于蒙古文编码国际标准而研制的蒙古文办公套件的实现方案,并为开发其他复杂文字的少数民族语言的办公套件提供了很好的借鉴作用。

蒙古文显示在OpenOffice.org办公套件中的实现

蒙古文是一种复杂文字,目前操作系统和办公套件都还不支持蒙古文的显示.OpenOffice.org是可以运行在Linux和Windows上跨平台的办公套件,它分别使用ICU LayoutEngine和Uniscribe进行复杂文字处理.本文以支持蒙古文处理的Linux版本OpenOiffice.org为基础,详细分析了OpenOffice.org在Linux和Windows系统上的复杂文本处理过程,采用Uniscribe与ICU相结合的方案,实现了OpenOffice.org在Windows平台上对蒙古文的显示.

沙地樟子松水分生理生态特征及其适应性——以科尔沁沙地东南缘为例

沙地樟子松天然分布于大兴安岭以西的呼伦贝尔草原红花尔基一带，分布范围虽然相对狭窄，但其具有重要的防风、固沙等生态功能，而且，该区沙地樟子松林的分布范围正呈现不断扩大的趋势。然而，在引种区（科尔沁沙地东南缘），20世纪70~80年代曾经引起国际关注的沙地樟子松人工林，自从90年代初以来，逐渐出现了以枯梢、生长下降，甚至死亡等为特征的衰退现象。与此同时，沙地樟子松人工造林仍在北方干旱、半干旱沙区大面积推广。面对如此具有重要防风固沙作用并在大范围推广的沙地樟子松人工林，解释其为何衰退，其机理如何，回答现存沙地樟子松人工林发展方向及培育等理论和实践问题，成为目前面临的巨大挑战。 本论文在对沙地樟子松天然分布区与引种区野外调查、气候差异性对比分析的基础上，结合对引种区沙地樟子松幼苗、幼树及中龄林的水分生理生态过程实验，研究了沙地樟子松在引种区自然条件和干旱胁迫下的光合生理和水分生理生态特征；重点分析了水势、气孔导度等生理因素和土壤含水量、光合有效辐射、气温、空气相对湿度等生态因素对净光合速率、蒸腾速率的影响。结果表明： 1）较低、较长的低温和降雪覆盖有利于沙地樟子松更好的生长；运用De Martonne干燥度指数对气候类型进行划分，沙地樟子松引种区（科尔沁沙地东南缘）生态系统应为草地或疏林草地生态系统。 2）引种区近50 a来年平均温度存在着明显的线性上升，平均每10 a增温0.185 ℃；该区年平均降水量没有显著的变化趋势，但是，在过去的50 a里，该区平均每15 a 左右出现1次大旱。 3）在引种区多年年平均降水量条件下，沙地樟子松幼苗80%以上的时间处于受胁迫的状态，17%的时间处于不受水分胁迫的状态，而仅有1%左右的时间处于不能利用土壤水分的状态；在不同密度、不同年龄的沙地樟子松人工林中，土壤可溶性盐总量都很低，对沙地樟子松林木生长不会造成盐分胁迫；由于地下水位的急速下降，目前，引种区大部分地方地下水不能被沙地樟子松所利用。 4）随着模拟年降水量的减少，沙地樟子松幼苗的生长明显受到抑制，针叶水势、蒸腾速率、光合速率均有下降，各部分生物量积累明显降低；当模拟年降水量低于350 mm时就已经对沙地樟子松的生长产生了较大的限制。 5）在科尔沁沙地东南缘，影响沙地樟子松生理生态特征的主要因素为水分条件，特别是在树高生长旺季以及生长末期，而在生长中期，主要是光照和水分共同影响沙地樟子松的生长；在沙地樟子松天然分布区（红花尔基），影响沙地樟子松生长季节中期生理生态特征的主要因素也是水分和光照条件，这与在科尔沁沙地东南缘樟子松生长中期观测到的结论一致。然而，与天然沙地樟子松相比，引种区沙地樟子松每天干物质的积累增加为天然分布区的3~13倍，每天蒸腾耗水量为天然分布区的7~19倍。 综合以上对引种区的生态气候、水分条件以及沙地樟子松本身生理生态特征的分析结果得出，引种区与天然分布区水、热差异导致引种区沙地樟子松在年内的生长期延长（与天然沙地樟子松相比），以及在生长季节每天蒸腾耗水量的剧增及耗水时间的延长；同时，在引种区由于年内降水分布极不均衡，冬季降雪覆盖少，导致4、5、9三个月份的水分极度亏缺，该季节引种区水分亏缺严重限制了沙地樟子松的生长。大面积营造纯林、地下水位急剧下降（目前，引种区大部分林地的沙地樟子松已不能利用地下水）以及引种区每15 a左右一次的特殊干旱是导致沙地樟子松死亡的最直接原因。从个体水平上来说，近50 a的引种驯化，沙地樟子松并没有完全表现出适应引种区生长环境的迹象。最后，基于以上对沙地樟子松人工林衰退分析的基础上，提出了对现存沙地樟子松人工林总体经营的方向及具体经营对策。

科尔沁沙地樟子松人工林土壤呼吸对水分变化的响应

土壤是陆地生态系统最大的碳库，其碳储量是大气碳储量的两倍。土壤呼吸是土壤碳库的最大输出途径。在干旱半干旱区降雨格局以及土壤水分条件的变化对土壤呼吸的影响具有重要意义。本研究以半干旱区科尔沁沙地东部樟子松人工林为研究对象，通过室内培养模拟研究、野外降雨量控制研究和降雨频率模拟及干湿交替模拟试验，研究了科尔沁沙地半干旱人工林生态系统土壤呼吸对水分变化的响应趋势，探讨了降雨格局变化对土壤呼吸的影响，结果表明： （1）土壤呼吸速率随温度和土壤含水量的升高分别呈指数和线性增长；温度和土壤含水量分别影响着土壤呼吸对土壤水分和温度的敏感性； （2）降雨量变化影响土壤呼吸日动态变化，降水量增加30%，土壤24h释放CO2量升高了35.9%，当降水量减少30%时，土壤24h释放的CO2量降低了59.6%，而且干旱降低了土壤呼吸日动态变化的幅度； （3）降雨量变化对土壤呼吸月季动态具有一定影响。降雨量增加30%，8~10月土壤总呼吸CO2释放速率升高40.7%~166.4%，土壤异养呼吸CO2释放速率升高40.5%~194.3%；降雨量降低30%使降雨较频繁的8月份土壤总呼吸CO2释放速率降低34.0%~70.0%，土壤异养呼吸CO2释放速率下降20.9%~ 64.0%，而在降雨较少的9~10月份降雨量的减少对土壤呼吸则没有显著影响； （4）降雨量的变化对土壤总呼吸和异养呼吸温度敏感性有一定影响。当降雨量减少30%时，土壤总呼吸的Q10值由5.4下降到2.22，土壤异养呼吸的Q10值由4.84下降到1.81； （5）用温湿度耦合作用经验模型Rt = 0.307e0.0064（W·T）来描述三个降雨处理样地土壤呼吸速率与土壤温度及土壤含水量的关系，可以解释土壤呼吸速率变异的80.2%； （6）在较高的温度条件下，降雨频率增加一倍时，土壤呼吸速率将升高约24%；当温度较低时，降雨频率对土壤呼吸速率的影响不显著； （7）土壤呼吸随着干旱程度的增加而逐渐下降，但当进行降水模拟后，土壤呼吸值迅速升高，可升高降水前的41.0% ~ 128%，而后又迅速下降，呈现明显的脉动（pulse）效应。

降雨量变化对科尔沁沙地东南部樟子松人工林主要生态过程的影响

水分条件是影响植物生长最主要的限制因子，降雨量变化作为全球变化的一个重要组成部分，其对干旱半干旱区陆地生态系统的影响甚至超过CO2浓度和温度的升高以及它们的共同作用对生态系统的影响。樟子松人工林是科尔沁沙地东南部主要的防风固沙林类型，研究未来降雨量变化对会对樟子松人工林产生怎样的影响，对樟子松人工林的可持续经营和科学管理有重要意义。本研究以樟子松人工林为研究对象，通过搭建遮雨棚，铺设灌溉设施，野外原状样地模拟三个降雨量梯度：降雨量减少30%、天然降雨量和降雨量增加30%，从樟子松人工林下土壤生态系统、樟子松针叶生理特性、樟子松的生长和林下植被结构与生产力三个角度研究降雨量变化对樟子松人工林主要生态过程的影响，主要结论如下： （1）以土壤矿质N含量为土壤N有效性的指标，2007年的数据表明降雨量减少时土壤N有效性显著升高，降雨量增加时土壤N有效性显著降低，出现了“水、N有效性的不同时性”，即土壤水分有效性高时N有效性低，而N有效性高时水分有效性低，这可能是该地区植物生长的主要限制因子，而不是简单的水分限制或者N素限制。 （2）降雨量降低时，樟子松针叶的丙二醛（MDA）含量显著升高，针叶N含量降低，樟子松光合速率下降，同时，樟子松针叶的叶绿素含量大部分月份不受降雨量减少的影响，而且针叶脯氨酸和可溶性蛋白含量升高，超氧化物歧化酶（SOD）活性的升高，表明了樟子松对水分胁迫的生理生态适应机制。 （3）降雨量减少时樟子松林下植被总盖度显著降低，优势种由黄蒿和狗尾草演变为绿珠藜和黄蒿；降雨量增加时樟子松林下植被总盖度显著升高，优势种演变为艾蒿。降雨量减少和增加时物种多样性都显著降低，导致了生物多样性丧失。 （4）降雨量减少时樟子松和其林下植被的生长由于水分胁迫都受到了抑制，樟子松的高生长和粗生长速率减缓，林下植被的ANPP和地下部分生物量降低，进而导致樟子松人工林的地上部分C储量降低；樟子松的成长速率减缓和林下植被地上地下生物量的降低意味着生态系统凋落物量和死亡根系的减少，这直接导致了土壤有机碳含量的降低，即土壤有机碳储量的降低；综合降雨量减少导致的樟子松人工林的地上部分C储量降低和土壤有机碳储量的降低，我们的结果表明降雨量减少导致樟子松人工林C储量降低，同样的道理，降雨量增加导致樟子松人工林C储量升高。 （5）降雨量减少时，保护凋落物可以增加地表覆被，抑制地面水分蒸发，地表凋落物还能起到蓄水保水的作用，提高土壤水分有效性；降雨量增加时保护凋落物可以增加土壤养分（尤其是N）的输入，提高土壤养分的有效性。

沙地樟子松人工林稳定性研究

本文分析了生态系统稳定性的含义、影响稳定性的时间空间尺度和干扰因子；对人工林稳定性的内涵作了解释，提出了人工林稳定性的评价标准；以此作为稳定性研究的理论依据。首先分析了影响沙地樟子松人工林稳定性的各种干扰因子，通过对沙地樟子松人工林造林成活、生长情况、对不良外界环境的抗御能力、对环境影响作用的大小、林分生产力和林分结构的评价分析。最后提出维持沙地人工林稳定的对策。

Short-term effect of targeted placements of sheep excrement on grassland in inner mongolia on soil and plant parameters

Grazing animal excrement plays an important role in nutrient cycling and redistribution in grazing ecosystems, due to grazing in large areas and return in small areas. To elucidate the changes to the soil and pasture caused by sheep urine, fresh dung, and compost patches, a short- term field experiment using artificially placed pats was set up in the autumn of 2003 in the Inner Mongolian steppe. Urine application significantly increased soil pH during the first 32 days in soil layers at depths of both 0 - 5 cm and 5 - 15 cm. Rapid hydrolysis of urea gave large amounts of urine- nitrogen ( N) as ammonium ( NH4+) in soil extracts and was followed by apparent nitrification from day 2. Higher inorganic N content in the urine- treated soil was found throughout the experiment compared with the control. No significant effects of sheep excrement on soil microbial carbon ( C) and soil microbial N was found, but microbial activities significantly increased compared with the control after application of sheep excrement. Forty- six percent of dung- N and 27% of compost- N were transferred into vegetation after the experiment. The results from this study suggest that large amounts of nutrients have been lost from the returned excrement patches in the degraded grassland of Inner Mongolia, especially from sheep urine- N.

Defoliation, nitrogen, and competition: effects on plant growth and resource allocation of Cleistogenes squarrosa and Artemisia frigida

Two species, Artemisia frigida Willd. (C-3, semishrub, and dominant on overgrazed sites) and Cleistogenes squarrosa (Trin.) Keng (C-4, perennial bunchgrass, and dominant or codominant on moderately grazed sites) were studied to determine the effects of defoliation, nitrogen (N) availability, competition, and their interactions on growth, biomass, and N allocation in a greenhouse experiment. The main treatments were: two nitrogen levels (NO = 0 mg N pot(-1), N1 = 60 mg N pot(-1)), two defoliation intensities (removing 60% of total aboveground biomass and no defoliation), and three competitive replacement series (monocultures of each species and mixtures at 0.5:0.5). Our results were inconsistent with our hypothesis on the adaptive mechanisms of A. frigida regarding the interactive effects of herbivory, N, and competition in determining its dominant position on overgrazed sites. Cleistogenes squarrosa will be replaced by A. frigida on over-grazed sites, although C. squarrosa had higher tolerance to defoliation than did A. frigida. Total biomass and N yield and N-15 recovery of C. squarrosa in mixed culture were consistently lower than in monocultures, whereas those of A. frigida grown in mixtures were consistently higher than in monocultures, suggesting higher competitive ability of A. frigida. Our results suggest that interspecific competitive ability may be of equal or greater importance than herbivory tolerance in determining herbivore-induced species replacement in semi-arid Inner Mongolian steppe. In addition, the dominance of A. frigida on overgrazed sites has been attributed to its ability to shift plant-plant interactions through (lap colonization, root niche differentiation, and higher resistance to water stress.