Somatic histone H3 alterations in pediatric diffuse intrinsic pontine gliomas and non-brainstem glioblastomas

To identify somatic mutations in pediatric diffuse intrinsic pontine glioma (DIPG), we performed whole-genome sequencing of DNA from seven DIPGs and matched germline tissue and targeted sequencing of an additional 43 DIPGs and 36 non-brainstem pediatric glioblastomas (non-BS-PGs). We found that 78% of DIPGs and 22% of non-BS-PGs contained a mutation in H3F3A, encoding histone H3.3, or in the related HIST1H3B, encoding histone H3.1, that caused a p.Lys27Met amino acid substitution in each protein. An additional 14% of non-BS-PGs had somatic mutations in H3F3A causing a p.Gly34Arg alteration.     

Rediscovered population of Mexican Plateau spotted whiptail lizard, Aspidoscelis septemvittata , from México, D.F.

Multiple surveys carried out by herpetologists in México, D.F., during the 1980s failed to find specimens of Aspidoscelis septemvitatta (Squamata: Teiidae). However, 10 specimens were recently collected to the east of México, D.F., inside a protected area, Sierra de Santa Catarina. The Sierra de Santa Catarina has been heavily modified by human activity and habitation. Morphological and natural history information about the specimens are presented, as well as notes on locality.     

Comparative life history for populations of the Sceloporus grammicus complex (Squamata: Phrynosomatidae)

A Teotihuacán population of the Sceloporus grammicus complex was compared with other previously studied populations (Parque Nacional Zoquiapan [PNZ], Monte Alegre Ajusco [MAA], Pedregal San Angel [PSA], Cantimplora [CA], Capulín, Laguna, Paredon, Michilia, and south Texas) for variations in several life history characteristics (SVL at sexual maturity, reproductive period, ovulation and gestation time, and litter size). Mean body size at sexual maturity of females from Teotihuacán was larger than PNZ, MAA, CA, and Capulín. Reproductive period (vitellogenesis, ovulation, gestation, and birth) for the Teotihuacán population was the shortest of all populations. In the Teotihuacán population, gestation time was similar to the Capulínand MAA populations but was shorter than all other populations except the Michilia population. Embryonic development at ovulation varied among populations, with Teotihuacán and Capulín showing earlier stages (stages 1) at ovulation than all other populations. Teotihuacán, PSA, PNZ, and Texas all showed similar litter size, which were larger than Laguna, Paredon, MAA, Capulín, and CA populations. Differences in reproductive characteristics of these populations could indicate phylogenetically constrained, reproductively isolated populations, or they may be explained as merely responses to different environments.     

Dynamics of a dwarf bear-poppy ( Arctomecon humilis ) population over a sixteen-year period

A population of the dwarf bear-poppy ( Arctomecon humilis Coville, Papaveraceae) at Red Bluff, Washington County, Utah, was monitored twice annually between 1987 and 2002. This is a narrowly endemic, gypsophilous species that has been formally listed as endangered since 1979. During the 16 years of observation, density of this species has fluctuated between 3 and 1336 individuals on the 0.07-ha monitoring plot. Moderate to large recruitments of seedlings occurred in 1992, 1995, and 2001. Seedling recruitments from a large, long-lived seed bank are triggered by abundant precipitation during the February-April period. At least 5.0 cm of rainfall is required during that interval to produce any seedlings. Seedlings experienced considerable mortality in the 1st few months of life in all observed cases. The average seedling initiated in the very large recruitment event of 1992 survived for only 2.6 years. Seedlings in that cohort that were alive 1 year after germination had an average longevity of 4.6 years. None of the seedlings that emerged in 1992 were still alive in October 2002. Mortality in this species was poorly correlated with fluctuations in precipitation or temperature. No epidemics of parasites or herbivores were observed. Mortality in the species appears to be caused by a variety of factors acting over a cohort's lifetime.     

Demography of the Yarrow's spiny lizard, Sceloporus jarrovii , from the central Chihuahuan Desert

The demography of a population of Yarrow's spiny lizard, Sceloporus jarrovii , was examined from 2004 to 2006 in the canyon Las Piedras Encimadas, located in Gomez Palacio, Durango, México. Lizards were studied using a mark-recapture technique. Reproduction in females occurred between November and May, coinciding with dry conditions. Reproductive activity was highest (percent of females with vitellogenic follicles or embryos) in the middle of the dry season (November and December). Thirteen percent of females reached sexual maturity at an average age of 8.5 months. The population structure was similar in spring and fall, but not in summer. A notable feature of summer, coinciding with the wet season, was the greater number of hatchlings and juveniles. The overall sex ratio did not differ from 1:1. The density of adults varied from 12 to 62 animals ? 0.5 ha –1 . Temperate and arid-adapted populations of S. jarrovii exhibited broad similarity in timing of the reproductive season, whereas factors such as density, growth, age at sexual maturity, and survivorship differed.     

聚合氯化铝组合芽孢杆菌发酵液法对链状裸甲藻孢囊种源萌发调控研究

对比不同浓度梯度的聚合氯化铝(poly aluminium chloride,以下简称"PAC")和不同发酵时间、不同投加量的Ba3芽孢杆菌(Bacillus)发酵液及两者组合法对链状裸甲藻(Gymnodinium catenatum)的除藻效果,用最佳投加量进行了沉积物种源萌发调控实验,探究了PAC组合菌发酵液方法对...     

毛乌素沙地的粉尘释放通量观测及DPM模型的野外验证

目前关于中国粉尘源区的释放通量观测数据很少, 被经常使用的DPM粉尘释放模型在中国源区的可靠性还没有得到验证. 2002年春季在毛乌素沙地开展了野外观测实验, 分别观测了跃移通量、< 10 μm的粉尘释放通量、温度和风速梯度. 观测期间平均摩阻风速在0.26~0.35 m·s-1之间, 实测的跃移通量约在0.07~8.00 g·m^-1·s^-1之间, 实测和模拟的跃移通量较为一致, 跃移通量方程经验系数取2.61比较合适; 在3次局地的粉尘释放过程中, 实测的粉尘释放通量约在1~3 mg·m^-2·s^-1之间, 模拟的粉尘释放通量偏高, 说明该模型在低风速条件下还需要校正. 通过与前人数据的比较, 发现松散的砂质土的跃移通量大于具有物理结皮的砂质土和存在大土壤团块的壤质土, 说明在相同摩阻风速条件下, 松散的砂质土的粉尘释放通量最大, 预示中国北方粉尘的主要源地在沙漠和沙漠化的土地.     

从古生物学到地球生物学的跨越

以学科体系和科学问题为导向, 对当前国际上出现的地球生物学从学科分类体系、形成背景、主要研究方向、亟待突破的分支学科及其与之相关的研究领域进行了评述. 作为地球科学与生命科学相结合而形成的新兴交叉学科, 地球生物学在地球科学中应具有独立的一级学科地位, 类似于地球化学和地球物理学. 地球生物学主要研究地球系统的生命运动, 涉及地球环境与生命系统的相互作用. 它的形成与发展既是当今科学技术发展的结果, 也是当今世界对所面临重大人类-环境-资源问题的响应. 分子地球生物学、地球微生物学、地球生态学、地球生理学等地球生物学中的二级学科还有待尽快突破, 以形成地球生物学的成熟理论框架和方法体系.     

几种有机多硫化物的摩擦膜和热膜的XANES分析

采用X射线吸收精细结构光谱(XANES)对烷基、苄基以及两种酰基有机多硫化物与钢表面反应生成的摩擦膜和热膜的化学特征进行了分析. 结果表明, 热氧化条件下, 4种多硫化物与钢表面反应生成的热膜的主要成分是FeSO₄, 酰基多硫化物BOOS形成的热膜的次表面和本体中还含有少量烷基二硫化物. 生成的摩擦膜中, 多硫化物的结构不同呈现出不同的特征, 其中烷基多硫化物最外层表面以烷基二硫化物为主, 苄基多硫化物最外层表面以FeSO₄为主, 两者摩擦膜的次表面主要是FeSO₄, FeS₂和亚砜的混合物, 本体是FeSO₄; 而两种酰基多硫化物摩擦膜的最外层表面都是以烷基二硫化物为主, 次表面和本体主要是FeS₂.     

奂疫关键点阻断剂点燃治疗黑色素瘤和癌症的希望

长期以来，癌症的治疗主要是通过外科手术、放疗以及使用具有细胞毒性的化疗等手段联合完成。近年来，随着科学家对癌症的细胞及分子生物学的研究不断深入，诞生了一系列新的化合物，这些化合物可以补充或替代上述传统的癌症治疗手段。例如，表l列举了针对晚期黑色素瘤的药物，其中一些可以对抗肿瘤细胞的免疫逃逸能力。