Summer evolution of the north polar cap of Mars as observed by OMEGA/Mars Express

The Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) visible-infrared imaging spectrometer extensively observed regions of Mars with latitudes above 70 degrees N in late 2004 (heliocentric longitude from Ls 93 degrees to Ls 127 degrees ). The extent of water ice at the surface and the size of ice grains were monitored as a function of time. Bright, small-grained frost, which initially covered a large fraction of the polar cap, waned in favor of large-grained ice. In outlying regions, dominated by large-grained ice, the albedo increased over the period. Evaluating the dust content was model dependent. However, contamination of ice by dust was low.     

Sulfates in the north polar region of Mars detected by OMEGA/Mars Express

The Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) imaging spectrometer observed the northern circumpolar regions of Mars at a resolution of a few kilometers. An extended region at 240 degrees E, 85 degrees N, with an area of 60 kilometers by 200 kilometers, exhibits absorptions at wavelengths of 1.45, 1.75, 1.94, 2.22, 2.26, and 2.48 micrometers. These signatures can be unambiguously attributed to calcium-rich sulfates, most likely gypsum. This region corresponds to the dark longitudinal dunes of Olympia Planitia. These observations reveal that water alteration played a major role in the formation of the constituting minerals of northern circumpolar terrains.     

Sulfates in Martian layered terrains: the OMEGA/Mars Express view

The OMEGA/Mars Express hyperspectral imager identified hydrated sulfates on light-toned layered terrains on Mars. Outcrops in Valles Marineris, Margaritifer Sinus, and Terra Meridiani show evidence for kieserite, gypsum, and polyhydrated sulfates. This identification has its basis in vibrational absorptions between 1.3 and 2.5 micrometers. These minerals constitute direct records of the past aqueous activity on Mars.     

Global mineralogical and aqueous mars history derived from OMEGA/Mars Express data

Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet.     

Phyllosilicate diversity and past aqueous activity revealed at Mawrth Vallis, Mars

Observations by the Mars Reconnaissance Orbiter/Compact Reconnaissance Imaging Spectrometer for Mars in the Mawrth Vallis region show several phyllosilicate species, indicating a wide range of past aqueous activity. Iron/magnesium (Fe/Mg)-smectite is observed in light-toned outcrops that probably formed via aqueous alteration of basalt of the ancient cratered terrain. This unit is overlain by rocks rich in hydrated silica, montmorillonite, and kaolinite that may have formed via subsequent leaching of Fe and Mg through extended aqueous events or a change in aqueous chemistry. A spectral feature attributed to an Fe2+ phase is present in many locations in the Mawrth Vallis region at the transition from Fe/Mg-smectite to aluminum/silicon (Al/Si)-rich units. Fe2+-bearing materials in terrestrial sediments are typically associated with microorganisms or changes in pH or cations and could be explained here by hydrothermal activity. The stratigraphy of Fe/Mg-smectite overlain by a ferrous phase, hydrated silica, and then Al-phyllosilicates implies a complex aqueous history.     

崇明白山羊遗传多样性的ISSR分析

应用ISSR分子标记对崇明白山羊3个群体和黄淮山羊群体进行遗传多样性分析。用筛选出的12条引物对127个个体进行扩增,共扩增出147条谱带,其中多态性谱带67条。分析结果显示:崇明白山羊遗传多样性较为丰富,在物种水平上平均多态位点百分率(PPB)=42.18%,Shannon's信息指数(Ho)=0.2085;在群体水平上,PPB=38.55%,Ho=0.1946。崇明白山羊各群体间遗传差异较小,遗传稳定性较高。UPGMA聚类分析显示:崇明白山羊3个群体间亲缘关系较近,优先聚为1支,再与黄淮山羊相聚。     

中籼杂交稻遗传多样性的RAPD分析

选用20个随机引物对15个在生产和育种上广泛使用的中籼杂交稻亲本进行遗传多样性分析。20个引物共扩增出205条带纹，其中多态性带为165条。不同引物的多态性频率有较大差异，但普遍较高，平均达95．33％。亲本间的遗传距离小，在0．1210－0．3913之间，平均0．2455。15个亲本按UPGMA法可明显地分为不育系（I类）和恢复系（Ⅱ类）两类，其中Ⅱ类又分为两个亚类（Ⅱ－1和Ⅱ－2）。类群内和类群间的遗传距离分析表明，不育系与恢复系内的遗传差异都较小，而且不育系的遗传变异较恢复系小；不育系和恢复系间的遗传距离只有0．2906，而且与恢复系两个亚类间遗传差异不显著，这说明杂交水稻亲本的遗传资源匮乏。亲本间的遗传差异小，这可能是限制当前杂交水稻产量的重要因素。增加亲本遗传多样性和扩大亲本间遗传差异是当前中籼杂交稻育种的重要任务之一。     

基于SRAP标记研究石竹属植物遗传多样性

石竹属花卉植物花色艳丽,有较高观赏价值,且具有较强耐逆性,是极为宝贵的基因资源。为从分子水平探究石竹属花卉种质的遗传多样性,利用SRAP分子标记构建了44份石竹属花卉种质的指纹图谱。经遗传多样性分析,44份石竹属花卉被划分为五大类群,与物种分类结果一致;种内分类结果也与花色、株型等指标分类结果相符。物种差异是石竹属植物类群划分的主要因素,种内划分则以花色、株型等指标为主。通过SRAP分子标记可以有效地区分石竹属花卉种质,为石竹属花卉种质资源鉴定与保护、育种应用和分子机理研究提供了技术支撑和理论基础。     

甜高粱生物学性状与SSR分子标记遗传多样性

为探讨甜高粱的遗传多样性,选取31份甜高粱品种资源,通过生物学性状的方差分析、相关分析、主成分分析、聚类分析和SSR分子标记试验,获得如下结果:13个生物学性状在品种资源间存在显著差异,说明品种资源间的产量和品质差异真实存在;生物学性状之间存在一定相关性,其中株高与茎粗、鲜质量和叶片数呈极显著正相关,茎粗与鲜质量、粗蛋白和粗脂肪呈极显著正相关;分蘖数与茎粗呈极显著负相关,茎粗与粗纤维呈极显著负相关。主成分分析可以将前4个主成分作为品质主因子、产量主因子、糖分和产量次因子,以及产量辅助因子;基于生物学性状的聚类分析可以将全部品种资源分成6大类群,其中第Ⅰ类属于高产型,第Ⅱ类属于高产低质型,第Ⅲ类属于高含糖量型,第Ⅳ、Ⅴ类群利用价值不大,第Ⅵ类属于高分蘖型。根据SSR分子标记分析结果计算得到甜高粱品种资源每个位点的多态信息含量(PIC)为0~0.757,基于SSR分子标记的聚类分析将全部品种资源聚为6大类群,这与生物学性状聚类结果相类似,但又不完全一致。     

Mars: is the surface colored by carbon suboxide?

The reflection spectrum of Mars can be well matched from 0.2 through 1.6 microns (and farther) by polymers of carbon suboxide, reflection spectra for which have now been measured. We propose that the reddish color of Mars might be attributed to carbon suboxide, not the commonly considered limonite or other iron-bearing minerals.     

利用小麦微卫星引物分析小麦及其近缘种遗传多样性

利用竹通大麦染色体上的引物218条对小麦SSR引物对小麦及其近缘种共22个材料进行PCR扩增。从中筛选到39对多态性高、重复性好的引物,这些引物可在供试材料中检测出213个等位基因变异,平均每个位点可检测到5．4个等位基因。位点多态性信息量（PIC）变幅为0．38～0．89,平均为0．57。NTSYS软件分析表明22份材料的遗传相似系数范围为0．46—0．94,平均遗传相似系数为0．67,聚类分析结果显示小麦、偃麦草、大赖草、黑麦均各自聚类,与传统的形态分类结果有较高的吻合度。这表明：①SSR可以应用于小麦与其近缘种的遗传多样性研究。②SSR揭示的小麦与其近缘物种间的多态性高,可以用来鉴定小麦近缘种。     

Molecular diversity and genetic structure of 380 sweetpotato accessions as revealed by SSR markers

Sweetpotato, Ipomoea batatas(L.) Lam., is an important food crop widely cultivated in the world. Evaluation of genetic relationships among diverse cultivars and landraces is necessary for efficient exploitation of genetic diversity in the existing germplasm resources. In the present study, a collection of 380 sweetpotato accessions assembled from different agro-climatic zones of China and other countries were genotyped using 30 SSR primer pairs. Model-based structure analysis separated the germplasm into three populations, P1, P2 and P3, containing 228, 133 and 19 accessions, respectively, which was consistent with the results of phylogenic and principal component analysis(PCA). Analysis of molecular variance(AMOVA) revealed significant genetic differentiation among inferred populations, accounting for 16.47% of the total molecular variance, however, the differences between the regions were not significant, the total variation were due to the differences between the genotypes within the population. Pairwise fixation index(F ST) suggested that populations P1 and P3 had the highest differentiation, while populations P1 and P2 had the lowest differentiation. The diversity among populations was wide, which confirmed the genetic distinction of populations. Through comparing model-based structure and domestication-based classification, it was found that the accessions of population P1 mainly belonged to modern cultivars, and the accessions of populations P2 and P3 basically corresponded to landraces, by which we suggest that modern cultivars maybe had experienced a two-step domestication history. Our results illustrated clear genetic relationships among 380 sweetpotato accessions, exhibiting the potential of accelerating the process of future sweetpotato breeding program by molecular marker based parental selection.     

Genetic diversity of Ustilago hordei in Tibetan areas as revealed by RAPD and SSR

Covered smut, which is caused by Ustilago hordei(Pers.) Lagerh., is one of the most damaging diseases of highland barley(Hordeum vulgare Linn. var. nudum Hook. f) in Tibetan areas of China. To understand the molecular diversity of U. hordei, a total of 27 isolates, which were collected from highland barley plants from Tibet, Sichuan, Qinghai, and Gansu provinces/autonomous region, were analyzed using random amplified polymorphic DNA(RAPD) and simple sequence repeat(SSR) markers. Among the 100 RAPD primers used, 24 primers exhibited polymorphism. A total of 111 fragments were amplified, of which 103 were polymorphic with a polymorphic rate of 92.79%. The average observed number of alleles(Na), effective number of alleles(Ne), Nei's genetic diversity(H), Shannon's information index(I) and polymorphism information content(PIC) value in the RAPD markers were 1.9279, 1.5016, 0.2974, 0.4503 and 0.6428, respectively. For the SSR markers, 40 of the 111 primer pairs exhibited polymorphism and provided a total of 119 bands, of which 109 were polymorphic and accounted for 91.60% of the total bands. The Na, Ne, H, I and PIC values of the SSR markers were 1.9160, 1.4639, 0.2757, 0.4211 and 0.4340, respectively. The similarity coefficients ranged from 0.4957 to 0.9261 with an average of 0.7028 among all the 27 isolates used. The dendrogram, which was developed based on the RAPD and SSR combined marker dataset showed that the 27 U. hordei isolates were divided into 3 clusters at similarity coefficient of 0.7314. We determined that RAPD and SSR markers can be successfully used to assess the genetic variation among U. hordei isolates. The RAPD markers revealed higher levels of genetic polymorphism than did the SSR markers in this study. There existed a moderate genetic difference among isolates. The molecular variation and differentiation was somewhat associated with geographical origin but not for all of the isolates.     

14份杏种质的ISSR分析

以冀光为试材,研究了PCR反应体系的主要成分及退火温度对杏ISSR扩增结果的影响。同时,从42对ISSR引物中筛选出12对扩增条带清晰、多态性好的引物进行扩增,并运用UPGMA聚类分析法,分析了12份杏种质的亲缘关系及多样性。结果表明:在20μL的反应体系中,模板DNA含量在10~80 ng均能得到较好的扩增;dNTP用量对扩增无明显影响;而引物、Mg2+的最适浓度分别为0.25μmol/L、0.25 mmol/L;Taq酶在0.5~4 U均能得到好的扩增条带;退火温度在50~52.1℃范围内均能得到清晰的条带;并在此基础上建立了杏ISSR反应体系。当相似系数在0.444~0.452之间时,将12份杏材料划分为3类:①普通杏(Amentacavulgaris),西伯利亚杏(A.sibirica),辽杏(A.mandshurica),藏杏(A.holosericea)类型;②仁用杏品种一窝蜂;③紫杏(A.dasycarpa)。     

我国近年审定的甘蓝型油菜品种的遗传多样性分析

【目的】分析我国近年审定的甘蓝型油菜品种的遗传多样性。【方法】利用筛选出的24对SSR引物,对我国1999年以后审定的66份甘蓝型油菜品种及4份杂交组合的遗传多样性进行分析,以主成分分析、Shaanon指数、Simpson指数以及AMOVA分析揭示我国4大冬油菜区品种的变异程度。【结果】利用24对SSR引物共检测到104条清晰的谱带,其中86条呈多态性,多态性比率为84.61%;平均每对引物扩增出4.3条条带,片段长度在100～600bp,多态性比率为50%～100%。70份甘蓝型油菜的遗传相似系数在0.40～0.93,平均为0.63。主成分分析结果显示,参试材料分布比较分散,并没有因来源地域相同而明显地聚在一起。在4大冬油菜区中,长江中游区品种Shaanon指数(1.593)和Simposon指数(0.732)最高,区内成对材料平均差异也最高(0.343 1)。不同大区油菜品种区内及区间分子方差分别为96.74%和3.26%。【结论】我国近年审定的冬油菜品种遗传多样性比较丰富;不同冬油菜区品种的变异以区内变异为主;长江中游区材料组内变异最为丰富,说明我国不同地区间材料交流比较频繁。     

Olivine and pyroxene diversity in the crust of Mars

Data from the Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) on the Mars Express spacecraft identify the distinct mafic, rock-forming minerals olivine, low-calcium pyroxene (LCP), and high-calcium pyroxene (HCP) on the surface of Mars. Olivine- and HCP-rich regions are found in deposits that span the age range of geologic units. However, LCP-rich regions are found only in the ancient Noachian-aged units, which suggests that melts for these deposits were derived from a mantle depleted in aluminum and calcium. Extended dark regions in the northern plains exhibit no evidence of strong mafic absorptions or absorptions due to hydrated materials.     

节节麦遗传多样性的SSR标记分析

节节麦是普通小麦的供体祖先种,具有丰富的遗传变异和优良性状,可用于拓宽现代小麦的遗传基础。本试验利用22个小麦D染色体组特异微卫星标记,对国内外的85份节节麦材料进行遗传多样性分析,结果共检测出195个等位变异,平均每个标记8.86个。节节麦染色体间平均等位变异顺序为6D>2D>5D>1D>7D>3D>4D;22个标记揭示的多态性信息指数——PIC值,分布在0.3385和0.8129之间,染色体间大小顺序为1D>5D>2D>4D>3D>6D>7D。研究表明,85份节节麦材料遗传多样性较高,为节节麦的有效利用提供了依据。     

濒危植物天目铁木遗传多样性的RAPD分析

濒危植物天目铁木Ostrya rehderiana现仅在天目山残存5株野生植株,是国家一级保护植物。为研究该物种繁殖与复壮的有效途径,利用随机扩增多态性DNA（RAPD）标记,对这5株天目铁木的遗传多样性和遗传分化进行基因组DNA多态性分析,统计18个扩增较为稳定的引物在5个DNA样品中扩增的电泳带总数与多态带的数目。结果显示：共扩增出176个DNA片段,片段大小为200~2 800 bp,其中多态性谱带为88条,占50%,表现出了丰富的RAPD多态性。根据遗传距离,利用UPGMA构建了个体亲缘关系树状图。结果表明,4号和5号植株间亲缘关系最近,遗传距离为0.133 5,1号和3号植株间亲缘关系最远,遗传距离为0.461 0,1号植株与其他4株的亲缘关系均较远,遗传距离为0.366 5~0.461 0,聚类时被聚在其他4株之外。这一结果与5株间物理距离分布的位置差异相符。     

Morphology and composition of the surface of Mars: Mars Odyssey THEMIS results

The Thermal Emission Imaging System (THEMIS) on Mars Odyssey has produced infrared to visible wavelength images of the martian surface that show lithologically distinct layers with variable thickness, implying temporal changes in the processes or environments during or after their formation. Kilometer-scale exposures of bedrock are observed; elsewhere airfall dust completely mantles the surface over thousands of square kilometers. Mars has compositional variations at 100-meter scales, for example, an exposure of olivine-rich basalt in the walls of Ganges Chasma. Thermally distinct ejecta facies occur around some craters with variations associated with crater age. Polar observations have identified temporal patches of water frost in the north polar cap. No thermal signatures associated with endogenic heat sources have been identified.     

Phobos transit of Mars as viewed by the viking cameras

A Viking orbiting spacecraft successfully obtained pictures of the martian satellite Phobos with Mars in the background. This is the first time that a single picture was obtained from a spacecraft which contained both a planet and a moon and had significant surface detail visible on both. The region of Mars below Phobos included volcanoes in the Tharsis Montes region. These pictures showed Phobos to be smaller than previously thought. The image of Phobos can be used as a control point to determine the map coordinates of surface features on Mars.