Cross-species chromosome painting in the Perissodactyla: delimitation of homologous regions in Burchell's zebra (Equus burchellii) and the white (Ceratotherium simum) and black rhinoceros (Diceros bicornis)

Conserved chromosomal segments in the black rhinoceros, Diceros bicornis (DB1, 2n = 84), and its African sister-species the white rhinoceros, Ceratotherim simum (CSI, 2n = 82), were detected using Burchell's zebra (Equus burchellii, EBU, 2n = 44) chromosome-specific painting probes supplemented by a subset of those developed for the horse (Equus caballus, ECA, 2n = 64). In total 41 and 42 conserved autosomal segments were identified in C simum and D. bicornis respectively. Only 21 rearrangements (20 fissions and I fusion) are necessary to convert the Burchell's zebra karyotype into that of the white rhinoceros. One fission distinguishes the D. bicornis and C simum karyotypes which, excluding hetero- chromatic differences, are identical in all respects at this level of resolution. Most Burchell's zebra chromosomes correspond to two rhinoceros chromosomes although in four instances (EBU 18, 19, 20 and 21) whole chromosome synteny has been retained among these species. In contrast, one rhinoceros chromosome (DBI1, CSI1) comprises two separate Burchell's zebra chromosomes (EBU11 and EBU17). In spite of the high diploid numbers of the two rhinoceros species their karyotypes are surprisingly conserved offering a glimpse of the putative ancestral perissodactyl condition and a broader understanding of genome organization in mammals. Copyright (C) 2003 S. Karger AG, Base

家马核基因组中线粒体核内插入序列分析

在各种真核生物核基因组中,存在一些由线粒体基因组转移进入核基因组中的DNA片段,这些被认为是分子化石的片段叫做线粒体核内插入序列(Numt).由于Numt与真实的线粒体序列高度相似,因此它的存在必然会成为PCR扩增线粒体DNA的不利因素.利用已经公布的家马(Equus caballus)基因组序列(2007年9月公布,GenBank登录号为NC 009144--NC 009175)对家马Numt进行了深入分析,其发现200个可能的Numt,长度范围为29到3727bp,其中有10个的长度大于800bp.分析结果显示由于不存在线粒体控制区域的疑似Numt,因此对基于此区域的群体遗传学研究不会产生影响.本研究还发现在家马进化过程中,第1号和27号染色体更倾向于接受线粒体序列的转移.以上结果将为今后马科动物的研究提供重要的参考信息,有助于避免在线粒体DNA研究中由于Numt污染的存在而得出错误的实验结果.

Karyotypic relationships of horses and zebras: results of cross-species chromosome painting

Complete sets of chromosome-specific painting probes, derived from flow-sorted chromosomes of human (HSA), Equus caballus (ECA) and Equus burchelli (EBU) were used to delineate conserved chromosomal segments between human and Equits burchelli, and among four equid species, E. przewalskii (EPR), E. caballus, E. burchelli and E. zebra hartmannae (EZH) by cross-species chromosome painting. Genome-wide comparative maps between these species have been established. Twenty-two human autosomal probes revealed 48 conserved segments in E. burchelli. The adjacent segment combinations HSA3/21, 7/16p, 16q/19q, 14/15, 12/22 and 4/8, presumed ancestral syntenies for all eutherian mammals, were also found conserved in E. burchelli. The comparative maps of equids allow for the unequivocal characterization of chromosomal rearrangements that differentiate the karyotypes of these equid species. The karyotypes of E. przewalskii and E. caballus differ by one Robertsonian translocation (ECA5 = EPR23 + EPR24); numerous Robertsonian translocations and tandem fusions and several inversions account for the karyotypic differences between the horses and zebras. Our results shed new light on the karyotypic evolution of Equidae. Copyright (C) 2003 S. Karger AG, Basel.

Novel cathelicidin-derived antimicrobial peptides from Equus asinus

In the present study, EA-CATH1 and EA-CATH2 were identified from a constructed lung cDNA library of donkey (Equus asinus) as members of cathelicidin-derived antimicrobial peptides, using a nested PCR-based cloning strategy. Composed of 25 and 26 residues, respectively, EA-CATH1 and EA-CATH2 are smaller than most other cathelicidins and have no sequence homology to other cathelicidins identified to date. Chemically synthesized EA-CATH1 exerted potent antimicrobial activity against most of the 32 strains of bacteria and fungi tested, especially the clinically isolated drug-resistant strains, and minimal inhibitory concentration values against Gram-positive bacteria were mostly in the range of 0.3-2.4 mu g center dot mL-1. EA-CATH1 showed an extraordinary serum stability and no haemolytic activity against human erythrocytes in a dose up to 20 mu g center dot mL-1. CD spectra showed that EA-CATH1 mainly adopts an alpha-helical conformation in a 50% trifluoroethanol/water solution, but a random coil in aqueous solution. Scanning electron microscope observations of Staphylococcus aureus (ATCC2592) treated with EA-CATH1 demonstrated that EA-CATH could cause rapid disruption of the bacterial membrane, and in turn lead to cell lysis. This might explain the much faster killing kinetics of EA-CATH1 than conventional antibiotics revealed by killing kinetics data. In the presence of CaCl2, EA-CATH1 exerted haemagglutination activity, which might potentiate an inhibition against the bacterial polyprotein interaction with the host erythrocyte surface, thereby possibly restricting bacterial colonization and spread.

卡拉麦里山有蹄类自然保护区蒙古野驴(Equus hemionus)和鹅喉羚(Gazella subgutturosa)食性、种群和栖息地研究

卡拉麦里山有蹄类自然保护区是世界著名的荒漠有蹄类自然保护区, 区内有蒙古野驴(E. hemionus)、鹅喉羚(G. subgutturosa)、盘羊(Ovis ammon)以及近期野放的普氏野马(E. przewalski)。经过多年有效保护和管理，区内蒙古野驴及鹅喉羚种群得到恢复并有较大增长。从2006年开始，我们在该保护区开展了蒙古野驴和鹅喉羚的食性构成、社群结构、种群密度、卧息及采食生境利用、季节性栖息地利用等方面的研究。主要结果如下： 采用粪样显微分析技术研究了蒙古野驴、鹅喉羚与家羊、家马和家骆驼3种家养动物春季、秋季和冬季食性组成及食物生态位。结果发现：(1) 该区域的蒙古野驴、鹅喉羚和家畜所采食的植物科数和种数都不相同，针茅、驼绒藜、蒿和梭梭在各自食谱中所占的比例不同, 但蒙古野驴、鹅喉羚和家畜主要采食针茅、驼绒藜、蒿和梭梭；(2) 春季、秋季和冬季这些野生与家养草食动物两两之间的食物生态位重叠均在0.8以上，最低为0.832(冬季：鹅喉羚和家马)，最高达到0.986(秋季：蒙古野驴和家羊；秋季：家马和家羊)。五种有蹄类之间的食物生态位重叠度也达到了0.3以上。表明在卡拉麦里山有蹄类自然保护区，上述野生动物及季节性进入该自然保护区的家畜之间均存在食物竞争。冬季积雪深，食物短缺, 荒漠有蹄类易因冻饿及疾病等造成死亡。因此，应采取限制秋冬季进入该自然保护区家畜数量及调整放牧区域等保护管理措施，对该区域荒漠有蹄类实施有效保护。 对蒙古野驴和鹅喉羚的集群行为进行了初步研究。将鹅喉羚或蒙古野驴集群划分为雌性群、雄性群、母仔群、雌雄混群和独羚或独驴5种类型。共统计蒙古野驴556群次，计8235匹次。其中，雌雄混群223群次, 占40%, 为最多的集群类型；其余为雄性群(24%)、独驴(19%)、雌性群(11%)和母仔群(6% )。不同集群大小的比例差异极显著 (P=0.000)。其中2-30匹的集群占69%，独驴占18%，其余为13%。最大集群为266匹。除独驴外，其余4种集群类型的集群大小存在极显著差异。独驴作为一种特殊的集群类型，其占雄性个体的比例达63%，说明雄性个体比雌性更容易形成独驴。观察记录到鹅喉羚1286群次，计9148只次。其中，雌雄混群459群次, 占35%,为最多的集群类型；其余为独羚(18%)、母仔群(18%)、雄性群(17%)和雌性群(12%)。不同大小集群的比例差异极显著(P=0.000)，其中2一15头的集群占73%， 16头以上集群占42%，独羚仅占3%，不同集群大小差异也极为显著(P=0.000)。除独羚外，其余4种集群类型的集群大小存在极显著差异。独羚作为一种特殊的集群类型，其雌性个体的比例占到55%，因此, 不能说明雄性比雌性更容易形成独羚。 分四个季节采用截线取样法，用DISTANCE5.0估计了蒙古野驴、鹅喉羚的密度和遇见率。根据DISTANCE5.0计算，该区域春季蒙古野驴种群密度为0.55±0.14匹/km2 (平均数±标准差,下同)，夏季为0.60±0.13匹/km2，秋季为0.78±0.19匹/km2和冬季为0.54±0.14匹/km2。春季、夏季、秋季和冬季的鹅喉羚种群密度分别为1.14± 0.18头/km2，0.95±0.12头/km2，1.08±0.18头/km2和1.54±0.31头/km2。将这些结果与本区域不同时期及不同地域的蒙古野驴、鹅喉羚密度和遇见率数据进行了比较对比。截线取样法为研究干旱地区的有蹄类动物提供了一种标准方法，本研究结果为卡拉麦里自然保护区蒙古野驴和鹅喉羚的长期监测提供了基础数据。 采用样方法研究了鹅喉羚夏季和冬季卧息生境选择。夏季测定了49个卧迹样方，36个对照样方；冬季测定了75个卧迹样方，75个对照样方。研究发现，春季鹅喉羚主要选择平滩、下坡位和无坡位、海拔高度910米以上、与水源距离较远、远离道路、远离居民点、隐蔽级高、中低植被密度和中高草本密度的区域作为卧息生境；而冬季则主要选择山坡、阳坡和半阴半阳坡、中上坡位和下坡位、海拔900～1000m范围、离道路501～1000m以及大于2000m的距离、靠近居民点、中低隐蔽级、中厚度(1.1-3cm)雪深、中高植被密度和中高草本密度的区域作为卧息生境。主成分分析表明，卡拉麦里山鹅喉羚夏季季卧息样方前4个主成分的累积贡献率达到86.57％，第1主成分主要反映卧迹样方的植物密度、草本密度、针茅密度、至最近居民点距离、至永久水源最近距离和海拔。冬季该区域鹅喉羚卧息样方前4个主成分的累积贡献率达到73.88％，第1主成分主要反映卧迹样方的植物密度、草本密度、针茅密度和坡度。 通过设立样方研究了蒙古野驴的采食生境。研究发现，夏季和秋季两个季节蒙古野驴主要在平滩和山沟采食。集中在无坡向的平滩、1001m以上的海拔高度、与水源距离较近、远离道路、远离矿区等人类活动点、植被盖度高、草本盖度高、植物多样性高、草本多样性高(P＜0.05)的区域采食。主成分分析表明，夏季影响蒙古野驴采食生境选择的环境因子是植物盖度、草本盖度、针茅盖度、植物密度、草本密度、针茅密度、植物种类、草本种类和禾本科种类。秋季影响蒙古野驴采食生境选择的环境因子是海拔、植物盖度、草本盖度、针茅盖度、植物密度、草本密度、针茅密度、植物种类、草本种类和禾本科种类。 利用卡山保护区不同季节野外种群调查数据，以3S技术为手段，评价了蒙古野驴和鹅喉羚季节性栖息地适宜性。首先把各季节蒙古野驴和鹅喉羚分布点图层，分别和固定水源点图层、道路图层、固定冬牧点图层和矿点图层进行叠加和距离查询，用Vanderploeg & Scavia’s选择指数(Ei*)分析了蒙古野驴和鹅喉羚季节性栖息地选择及其主要影响因素，建立了固定水源点、植被、道路、固定冬牧点和矿点对蒙古野驴和鹅喉羚栖息地影响强度的评价标准。通过缓冲区分析，分别研究了固定水源点、道路、固定冬牧点、矿点对蒙古野驴和鹅喉羚季节性栖息地的影响。通过缓冲区分析，综合研究了与人类活动有关的道路、固定冬牧点和矿点因子对蒙古野驴和鹅喉羚季节性栖息地的影响。最后将固定水源点、植被、道路、固定冬牧点和矿点等5个因子结合起来通过地图综合查询研究分析了这些因子对蒙古野驴和鹅喉羚季节性栖息地的综合影响，在固定水源点较适宜以上范围给出了该保护区蒙古野驴和鹅喉羚季节性不同适宜等级的生境面积。 我们建议采取以下积极措施来保护卡山保护区荒漠生态系统多样性以有效保护该区域内栖息的蒙古野驴和鹅喉羚：提高保护区周边社区政府的认识，提高公众参与自然资源和生物多样性保护的意识；加强水源地建设，积极采取飞播等措施,恢复植被，提高栖息生境质量；逐步限制进入卡拉麦里山越冬渡春的家畜数量；严格进入卡山保护区采矿制度，取缔非法矿业；加强草原围栏生态通道建设；与蒙古国合作建立跨国界的国际自然保护区；建立卡山自然保护区自然资源有偿使用机制；开展长期蒙古野驴和鹅喉羚种群监测。