Regeneration and identification of interspecific asymmetric somatic hybrids obtained by donor-recipient fusion in cotton

Asymmetric hybrids between Gossypium hirsutum （YZ-1） and G. davidsonii were obtained by donor-recipient fusion. YZ-1 was considered the recipient and was pretreated with iodoacetamide （IOA）, while G. davidsonii was considered the donor and was irradiated with ultraviolet （UV） before fusion. YZ-1 protoplasts stopped growth when treated with 0.5 mmol/L IOA for 20 min, and G. davidsonii protoplasts stopped growth when irradiated with 38.7 J/cm2 UV for 30 s. Asymmetric somatic hybrids were obtained by electrofusion between the separately treated protoplasts of the 2 species. The regenerated plants were identified by morphological, cytological, and molecular analysis. Most regenerated plants derived from fused protoplasts displayed new morphology; some were intermediate between the two parents and a few displayed recipient-like morphology. Chromosome numbers in these somatic hybrids mostly ranged from 40 to 73. The hybridity was confirmed by random amplified polymorphic DNA and simple sequence repeat analysis. Organelle DNA inheritance of the YZ-1 and G. davidsonii somatic hybrid was investigated by cleaved amplified polymorphism sequence and chloroplast simple sequence repeat analysis, which indicated that recombination and rearrangements might have occurred in some regions of mitochondrial and chloroplastic DNA. This is the first report of completely asymmetric hybrid production via donor–recipient fusion between G. hirsutum and G. davidsonii, which is a novel case in hybrid production following the symmetric fusion and asymmetric fusion based on UV irradiation in cotton.     

基于DFA方法的珠江流域极端降水阈值研究

 流域极端降水事件发生频率低、样本少,其阈值定义存在定义方式不统一、方法多样等不确定性和无规则性问题。论文以珠江流域为研究区域,系统总结了绝对临界值法、百分位值法、极值分布拟合法在确定流域极端降水阈值存在的不确定性问题,并尝试运用DFA方法,研究探讨了该方法在确定流域极端降水阈值的物理机制及其适用条件。研究表明, DFA方法以系统动力学为基础,通过分析极端降水事件对降水时间序列长程相关性的影响,由此寻求流域极端降水阈值,能较好反映流域降水序列的统计效应和物理背景,比较适合流域极端降水阈值分析。     

主成分分析在污灌区土壤分析中的应用

叙述了主成分分析的原理及其在污灌区土壤中的应用,并对阜新市东梁桥污灌区土壤中的重金属含量进行了分析研究。首先在研究区内选择10个采样点,并对其表层土分别采样,进行Cr、Ni、Pb、Cu、Zn、Cd等重金属分析,识别出主要污染因子,并对1~#和4~#进行剖面采样,共采集剖面样品8个,进而采用主成分分析法对该地区的重金属数据进行分析,确定出主成分的个数,为东梁桥污灌区进行重金属污染分析减轻了工作量,并且获得了选择最佳变量的效果。     

Multiple transgenes Populus xeuramericana ＇Guariento＇ plants obtained by biolistic bombardment

A JERF36 regulation gene, a selection marker gene （NPT-Ⅱ）, and the foreign genes levansucrase （SacB）, Vitreoscilla hemoglobin （vgb）, and Binary coleopterus insect resistance （BtCry3A＋OC-I） were co-transferred into Populus xeuramericana ＇Guariento＇ using biolistic bombardment; 25 kanamycin resistant plants were obtained, The results of PCR and Southern hybridization showed that the foreign genes had been integrated into the genome of P, xeuramericana ＇Guariento＇ and 5 genes were all transferred into 7 poplar plants, The results of a BtCry3A ELISA experiment indicated that the BtCry3A gene was expressed in the 7 transgenic poplar plants, and these plants grew well on coastal saline land,     

Branched glycerol dialkyl glycerol tetraethers and paleoenvironmental reconstruction in Zoigê peat sediments during the last 150 years

Branched glycerol dialkyl glycerol tetraethers (GDGTs) were analyzed in peat samples taken from the Zoigê grassland, located on the eastern margin of the Qinghai-Tibetan Plateau. The mean annual air temperature (MAAT) and pH in the 210 Pb-dating peat core were reconstructed based on the cyclization of branched tetraethers (CBT) and methylation of branched tetraethers (MBT) indices for the last 150 years. The results showed that the MAAT and pH values involved three stages of variation over the last 150 year...     

Temporal and spatial variations in the Palmer Drought Severity Index over the past four centuries in arid, semiarid, and semihumid East Asia

Based on a database of 106 annually resolved tree-ring chronologies and 244 Palmer Drought Severity Index(PDSI)grid data,we attempted to reconstruct gridded spatial drought patterns in each year over the past four centuries in the arid,semiarid,and semihumid East Asia.The results showed that these regions mainly experienced drought events during the periods from AD 1601 to AD 1652,AD 1680 to AD 1718,AD 1779 to AD 1791,AD 1807 to AD 1824,AD 1846 to AD 1885,and AD 1961 to AD 1999.In the middle of the 16th century,severe droughts occurred mainly in North China;during the period from AD 1876 to AD 1878,droughts occurred in most parts of northern China;and from the 1920s to 1940s,catastrophic drought events spread across almost all of northern China and Mongolia.These historical drought events caused severe ecological and environmental problems and substantially affected the development of human society.In these regions,temperature and summer monsoon precipitation are the main factors influencing drought events.In western areas,PDSI and temperature exhibit a close relationship,whereas in eastern areas,summer monsoon rainfall is the dominant factor influencing variations in PDSI.     

Houart-Dupont钙振荡模型的复杂动态

运用中心流形定理和分岔理论分析了Houart-Dupont钙振荡模型的非线性动态,包括随参数变化时平衡点的类型及其稳定性的变化,从理论上严格证明了系统振荡现象产生与消失是由于平衡点发生了2次supercritical Hopf分岔导致的。通过运用matlab软件进行数值模拟,验证了理论分析结果的正确性。     

Reconstructing mean maximum temperature of growing season from the maximum density of the Schrenk Spruce in Yili, Xinjiang, China

To study the historical temperature variation in Yili of Xinjiang, the tree-ring chronologies of maximum density （MXD） and tree-ring width （TRW） were established with the Schrenk Spruce （Picea schrenkiana Fisch. et Mey） collected from six sites to analyze the characteristics and ability of response to climate change. The results suggest that the MXD chronology of the Schrenk Spruce from different sampling sites responded to climate change well and were positively correlated with the mean maximum temperature and the mean temperature from April to August in the study area. The mean maximum temperature anomaly from April to August, spanning the years from 1848 to 2000, was reconstructed by three MXD chronologies which were selected by stepwise regression. The reconstructed function was stable and explained 56.2% of the variance. The reconstructed results indicated a cold span of 153 years in spring and summer from the beginning of the 1950s to the beginning of the 1970s in the Yili valley. No strongly increasing tendency was detected in the mean maximum temperature anomaly from April to August during this reconstructed period.     

Encumbering the intramolecular π donation by using a bridge: A strategy for designing metal-free compounds to hydrogen activation

On the basis of the FLP (frustrated Lewis pair) principle, a new strategy has been proposed to construct the “frustration” in designing metal-free hydrogen activation compounds, by using FMO (frontier molecular orbital) analyses and quantum mechanics calculations. Unlike the known FLPs which use bulky substituents to prevent them from forming stable Lewis acid/base complexes, the new approach encumbers the intramolecular π donation from the electron donor to the acceptor (e.g. in BH₂NH₂) by using a CH₂ bridge (giving BH₂CH₂NH₂). The strategy is simple and effective. Its effectiveness is demonstrated by the small hydrogen activation energy (12.0 kcal/mol) of the model molecule (BH₂CH₂NH₂), which is significantly less than the 42.7 kcal/mol of BH₂NH₂ and also less than the 18.5 kcal/mol of BH₂PH₂ whose derivative, R₂PB(C₆F₅)₂, has been experimentally shown to be able to activate hydrogen. We also exemplified how to use the strategy to design experimentally more realizable molecules. The example shows promises as a hydrogen activation agent. The strategy can be used to design metal-free catalysts for direct hydrogenation.