Identification of an S5n allele in Oryza rufipogon Griff. and its effect on embryo sac fertility

Oryza rufipogon exhibits abundant genetic diversity and contains many elite genes. In this work, a total of 441 accessions of O. rufipogon were genetically examined using the functional marker S5n, revealing that 18 accessions carried the S5n allele with a heterozygous genotype (S5nS5i/j). Of these accessions, 14 were from Guangdong Province, 2 from Guangxi Zhuang Autonomous Region, 1 from Hainan Province and 1 from Jiangxi Province. Further sequence analysis spanning both sides of the deletion in S5n allel...     

Mining rice new germplasm containing S5n gene by functional molecular marker and sequencing

Inter-subspecific hybrids between indica and japonica varieties yield strong biological heterosis, but it is difficult to utilize the hybrids directly in commercial production due to sterility of F1. A special gene S5^n may overcome the hybrids sterility, which is caused by the interaction between S5 loci. Recently, S5^n had been cloned, and it was revealed containing a large DNA deletion sequence that made the gene nonfunctional, compared to S5^i or S5^j. We designed a pair of primers flanking the deletion sequence of Ssn, and then applied to distinguish the varieties with S5^n or non-S5^n, convincing result suggested that the primers could be served as functional molecular marker to efficiently identify the new germplasm with S5^n, Using the functional marker, we surveyed 197 varieties from China National Micro-core Rice Collection, and found ten of which represented S5^n including following varieties： Haobuka, Sanbangqishiluo, Mubanggu, Xiaohonggu, Mowanggu＇neiza, Laozaogu, Fanhaopi, Feie＇nu02, Baoxie-7B, Teqingxuanhui. Among them, two varieties Sanbangqishiluo and Laozaogu was previously reported to contain S5^n gene. Further sequence analysis on the DNA sequence covering both sides of deletion in S5^n of the 10 varieties confirmed that the detected sequences in above varieties was identical with those of varieties containing S5^n, such as 02428 and Linglun. These results suggested that the gene in S5 locus of the ten varieties was also nonfunctional and it proved the presence of S5^n gene.     

Light emission of double-walled carbon nanotube filaments doped with yttrium and europium

As the potential applications of carbon nanotubes in the field of electroluminescence,elements yttrium and europium were introduced to modify the emission properties of double-walled carbon nanotubes(DWNTs)to obtain higher efficacy and other properties.The light emission spectrum of the Y-Eu-doped DWNT filament is suppressed in the near-infrared range,while enhanced in the mid-infrared range.The doped DWNT filament can reach higher efficacy than that of the pure DWNT filament at the same input power and can...     

基于国产卫星数据的深圳城市化进程中土地利用/覆盖变化探讨

土地利用/覆盖变化是全球变化中的重要组成部分,城市化进程将导致大规模的土地利用/覆盖变化.文中首先分别对1999年、2006年、2010年的CBERS和HJ-1B数据进行几何校正、拼接裁剪、分类等处理,生成土地利用/覆盖分类图,然后分别计算求得深圳市1999年到2006年和2006年到2010年的土地利用/覆盖变化转移矩阵.在此基础上,研究深圳市从1999年到2010年期间土地利用/覆盖变化的空间过程.结果表明:深圳市在快速城市化进程中发生了大规模的土地利用/覆盖变化,大量的草地、耕地、未利用土地转化为城镇用地,草地和林地之间部分结构相互转化调整.同时,10年来深圳市土地利用/覆盖变化区域差异明显,伴随着宝安和龙岗两区城市化进程加快,关外土地利用/覆盖变化强度逐渐加强,而关内逐渐减弱.在深圳城市化进程中,城镇用地重心呈现出向北部扩展的趋势.     

Molecular evolution of rice S 5 n and functional comparison among different sequences

The wide compatibility gene, S ₅ ⁿ , can overcome embryo sac sterility between indica and japonica subspecies of rice. Therefore, it is very important to characterize the features of the S ₅ ⁿ sequence to reveal the origin and evolution of S ₅ ⁿ . In this paper, 26 cultivated rice haplotypes and 22 wild rice accessions harboring S ₅ ⁿ were used to sequence S ₅ ⁿ . The results showed that 15 genotypes among the 48 materials were fully consistent with control cultivar 02428 (CK). The other 33 accessions had different degrees of variation in the S ₅ ⁿ sequence. Variations in the coding region mainly occurred in the second exon and eight materials showed a 10-bp deletion at 1710?C1719 bp, including wild (O. nivara) and cultivated rice, such as IRW501 and Yuetai B. S ₅ ⁿ sequences were not biased and evolved neutrally. The 48 materials could be divided into 4 categories using a phylogenetic tree of the amino acid sequences. Most of the wild rice clustered together, and the cultivated rice clustered into another group. Eight cultivated rice and O. nivara (wild rice) clustered in another group, which were found to lack 10 consecutive bases in exon 2. Eight rice varieties with high numbers of differences in their S ₅ ⁿ coding regions were crossed with testers (typically indica and japonica) to produced test cross F₁ populations. The F₁s were examined for their ability to overcome indica-japonica hybrid sterility. The result showed that the embryo sac fertility of S ₅ ⁿ -containing hybrids increased significantly compared with control hybrids, but there were no differences among the materials with divergent sequences, indirectly proving that S ₅ ⁿ is a non-functional gene.     

Cytological mechanisms of interspecific incrossability and hybrid sterility between Oryza sativa L. and O. alta Swallen

Oryza sativa and O. alta belong to AA and CCDD genomes in Oryza, respectively. Interspecific repro-ductive isolation limits the transfer of favorable genes from O. alta into O. sativa. The cytological mechanisms of interspecific incrossability and hybrid sterility between O. sativa and O. alta were studied systematically in this paper. We indentified two cytological causes of interspecific incrossabil-ity. First, we observed embryo sac incompatibility that caused fertilization barriers of variable severity such as non-fertilization, fertilization stagnation and egg cell single-fertilization. Second, we observed hybrid inviability, the major cause for incrossability, apparent from hybrid embryo developmental stagnation and embryo abortion. Hybrid sterility included both embryo sac sterility and pollen sterility. The hybrid embryo sac was completely sterile and exhibited mainly embryo sac degeneration. Hybrid pollen was also sterile and mainly typical abortive. Hybrid sterility was mainly caused by severely ab-normal meioses of megasporocytes and pollen mother cells; it is the most important abnormality, being chromosome sterility. Several methods are suggested to overcome the interspecific reproductive iso-lation between O. sativa and O. alta.     

Luminescence of carbon nanotube bulbs

Carbon nanotube (CNT) bulbs made of decimeter-scale double-walled carbon nanotube (DWCNT) strands and films were fabricated and their luminescence properties, including the lighting efficiency, voltage-current relation and thermal stability were investigated. The results show that the DWCNT bulb has a comparable spectrum of visible light with tungsten bulb and its average efficiency is 40% higher than that of a tungsten filament at the same temperature (1400―2300 K). The nanotube filaments show both resistance and thermal stability over a large temperature region. No obvious damage was found for a nanotube bulb illuminating at 2300 K for more than 24 hours in vacuum.     

Identifying neutral allele Sb at pollen-sterility loci in cultivated rice with Oryza rufipogon origin

Pollen sterility is commonly found in the intra-specific hybrids of indica and japonica rice, which is one of the main constrains for the utilization of heterosis between indica and japonica. Six loci controlling the pollen sterility of F1 between indica and japonica have been identified from previous studies. Neutral alleles at each locus are potential to overcome the F1 pollen sterility associated with the locus. Therefore, exploitation and utilization of neutral alleles are of significant importance. The present research was based on fine mapping of the F1 pollen-sterility gene Sb and the abundant genetic diversity of Oryza rufipogon Griff. indigenous to Gaozhou, Guangdong Province （referred to as Gaozhou wild rice）. Crosses were made using Taichung65 （with the genotype of Sb^jSb^j and referred to as El） and its near-isogenic line of F1 pollen sterility gene Sb（with the genotype of Sb^iSb^i, E2） as female parents, and 12 different accessions of Gaozhou wild rice as male parents. F1 pollen fertility was examined to identify the materials having the neutral alleles at the F1 pollen-sterility locus. Segregation of 4 molecular markers tightly linked with the Sb locus was analyzed in the F2 populations derived from the FlS carrying the neutral gene. The pollen fertility related to the 3 genotypes of the molecular markers was also checked by statistical test to determine whether it was consistent with the hypothesis. The results showed that the pollen fertility of two F1s from one accession of Gaozhou wild rice （GZW099） with E1 and E2 was （89.2±21.07）% and （85.65±1.05）%, respectively. Both of them were fertile and showed no significant difference by t-test. Segregation of the 3 genotypes of the 4 molecular markers followed the expected Mendelian ratio （1：2：1） in the F2 populations. There was no significant difference for the averaged pollen fertility of the plants related to the 3 genotypes, suggesting that no interaction exists between the alleles at the Sb locus in GZW099 and Taichung65 or E2. Evidentially, GZW099 carried the neutral gene （named Sb″Sb″） at the Sb locus, which provides valuable theoretical basis and resources for further studying and overcoming the sterility of indica-japonica hybrids.     

Spread of double-walled carbon nanotube membrane

A single-layer double-walled carbon nanotube (DWNT) membrane, with 100 cm2 in area, 50 nm in thickness, was spread by adding a few drops of ethanol (or acetone) on the purified DWNTs. Compared with acetone, ethanol is more efficient in spreading DWNT films. The spreading rate of DWNT mem-brane increases with the ethanol concentration, and it also first increases with temperature (below 60℃), then decreases as the temperature rises to above 60℃.     

Estimated evolutionary tempo of East Asian gobionid fishes (Teleostei: Cyprinidae) from mitochondrial DNA sequence data

The rapid development of molecular phylogenetic analysis has provided a new path to investigate the tempo of evolution.In this work,a rather complete molecular phylogeny of the East Asian gobionid fishes was constructed based on mtDNA cytochrome b gene sequences.Molecular clock analysis was then applied to investigate the speciation tempo of this group.The phylogenetic analysis revealed four major groups that were in agreement with previous studies.Lineage numbers plotted over time indicate that gobionid li...