P_(psbA)驱动的类金属硫蛋白基因smtA在鱼腥藻的表达和镉离子抗性的提高

中国科学院回国留学人员择优基金资助

湖鲟微卫星DNA引物应用于中华鲟亲子关系分析的初步研究

利用湖鲟(Acipenser fulvescens)的4对微卫星引物对中华鲟随机个体样本进行PCR扩增,分析电泳结果发现,4对引物均可在中华鲟个体中得到稳定的同源序列,其中2对引物所探测到的等位基因数目较多,在个体间表现出较高的多态性,利用它们产生的DNA指纹图谱,能够对1999年度获得的中华鲟亲鱼样本进行有效的个体区分。并且这两对湖鲟的微卫星引物在对1999年度已知亲本的同一家系中的中华鲟随机个体的分析中,表现为按照孟德尔方式进行共显性遗传。证明这2对微卫星引物可以用于鉴别中华鲟人工放流个体和自然繁殖个

Generalized power method for sparse principal component analysis

In this paper we develop a new approach to sparse principal component analysis (sparse PCA). We propose two single-unit and two block optimization formulations of the sparse PCA problem, aimed at extracting a single sparse dominant principal component of a data matrix, or more components at once, respectively. While the initial formulations involve nonconvex functions, and are therefore computationally intractable, we rewrite them into the form of an optimization program involving maximization of a convex function on a compact set. The dimension of the search space is decreased enormously if the data matrix has many more columns (variables) than rows. We then propose and analyze a simple gradient method suited for the task. It appears that our algorithm has best convergence properties in the case when either the objective function or the feasible set are strongly convex, which is the case with our single-unit formulations and can be enforced in the block case. Finally, we demonstrate numerically on a set of random and gene expression test problems that our approach outperforms existing algorithms both in quality of the obtained solution and in computational speed. © 2010 Michel Journée, Yurii Nesterov, Peter Richtárik and Rodolphe Sepulchre.

Nonlinear drillstring dynamics analysis

This paper studies the dynamical response of a rotary drilling system with a drag bit, using a lumped parameter model that takes into consideration the axial and torsional vibration modes of the bit. These vibrations are coupled through a bit-rock interaction law. At the bit-rock interface, the cutting process introduces a state-dependent delay, while the frictional process is responsible for discontinuous right-hand sides in the equations governing the motion of the bit. This complex system is characterized by a fast axial dynamics compared to the slow torsional dynamics. A dimensionless formulation exhibits a large parameter in the axial equation, enabling a two-time-scales analysis that uses a combination of averaging methods and a singular perturbation approach. An approximate model of the decoupled axial dynamics permits us to derive a pseudoanalytical expression of the solution of the axial equation. Its averaged behavior influences the slow torsional dynamics by generating an apparent velocity weakening friction law that has been proposed empirically in earlier work. The analytical expression of the solution of the axial dynamics is used to derive an approximate analytical expression of the velocity weakening friction law related to the physical parameters of the system. This expression can be used to provide recommendations on the operating parameters and the drillstring or the bit design in order to reduce the amplitude of the torsional vibrations. Moreover, it is an appropriate candidate model to replace empirical friction laws encountered in torsional models used for control. © 2009 Society for Industrial and Applied Mathematics.

一种降解石油烃的淡水藻类——坑形席藻

坑形席藻(Phormidium foveolarum Gom.)是长期培养于含石油烃基质的淡水蓝藻。测定了坑形席藻降解正十四烷时的耗氧量和降解后残留的烃浓度,以及对长期培养于石油烃基质的坑形席藻细胞进行了电镜观察。结果表明:(1)坑形席藻对石油烃具有吸附和降解能力,可以降低基质中的烃浓度;(2)在黑暗条件下,坑形席藻降解烃过程中的耗氧量,随反应时间的延长而递增;(3)长期以烃为基质生长的坑形席藻,发生着一定的细胞学变化,出现油滴和较多的大型颗粒物质。

Comparison of stationary acoustic monitoring and visual observation of finless porpoises

The detection performance regarding stationary acoustic monitoring of Yangtze finless porpoises Neophocaena phocaenoides asiaeorientalis was compared to visual observations. Three stereo acoustic data loggers (A-tag) were placed at different locations near the confluence of Poyang Lake and the Yangtze River, China. The presence and number of porpoises were determined acoustically and visually during each 1-min time bin. On average, porpoises were acoustically detected 81.7 +/- 9.7% of the entire effective observation time, while the presence of animals was confirmed visually 12.7 +/- 11.0% of the entire time. Acoustic monitoring indicated areas of high and low porpoise densities that were consistent with visual observations. The direction of porpoise movement was monitored using stereo beams, which agreed with visual observations at all monitoring locations. Acoustic and visual methods could determine group sizes up to five and ten individuals, respectively. While the acoustic monitoring method had the advantage of high detection probability, it tended to underestimate group size due to the limited resolution of sound source bearing angles. The stationary acoustic monitoring method proved to be a practical and useful alternative to visual observations, especially in areas of low porpoise density for long-term monitoring.

The phylogenetic relationships of the gobioninae (Teleostei : Cyprinidae) inferred from mitochondrial cytochrome b gene sequences

The Gobioninae are a group of morphologically and ecologically diverse Eurasian freshwater cyprinid fishes. The intergeneric relationships of this group are unresolved and the possible monophyly of this subfamily remains to be established. We used complete mitochondrial cytochrome b gene sequences from most genera within the gobionine group, in addition to a selection of cyprinid outgroups, to investigate the possible monophyly of this group and resolve the interrelationships within the group. Our results support the monophyly of the Gobioninae and identify four monophyletic groups within the subfamily; the Hemibarbus group, the Sarcocheilichthys group, the Gobio group, and the Pseudogobio group. The morphologically aberrant genera Gobiobotia, Xenophysogobio and Gobiocypris are included in the Gobioninae, with the latter a sister group of Gnathopogon.

pkn22 (alr2502) encoding a putative Ser/Thr kinase in the cyanobacterium Anabaena sp PCC 7120 is induced by both iron starvation and oxidative stress and regulates the expression of isiA

In cyanobacteria, the isiA gene is required for cell adaptation to oxidative damage caused by the absence of iron. We show here that a putative Ser/Thr kinase gene, pkn22 (alr2052), is activated by iron deficiency and oxidative damage in Anabaena sp. PCC 7120. A pkn22 insertion mutant is unable to grow when iron is limiting. pkn22 regulates the expression of isiA (encoding CP43') but not of isiB (encoding flavodoxin) and psbC (CP43). Fluorescence measurement at 77 K reveals the absence of the typical signature of CP43' associated with photosystem I in the mutant under iron-limiting conditions. We propose that Pkn22 is required for the function of isiA/CP43' and constitutes a regulatory element necessary for stress response. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Molecular variation of Bothriocephalus acheilognathi Yamaguti, 1934 (Cestoda : Pseudophyllidea) in different fish host species based on ITS rDNA sequences

The molecular variation in Bothriocephalus acheilognathi Yamaguti, 1934 from 11 species of freshwater fish collected in Australia, China, the Czech Republic, England and Hawaii was investigated by determining the nucleotide sequences of the internal transcribed spacer region. The length of the first and second internal transcribed spacer sequences of multiple individuals ranged from 553 to 571 bp and 553 to 615 bp, and the G + C content from 53.1 to 53.5%. The percentage sequence divergence varied between 0 and 0.9% in the ITS1 and 0 and 6.6% in the ITS2, respectively, indicating the occurrence of intraspecific variation. It is demonstrated that the fragment length variation resulted primarily from microsatellite polymorphisms present in the ITS region, especially in the ITS2 region. Phylogenetic analyses revealed that B. acheilognathi examined in this study consisted of three closely related genotypes with certain degrees of host-specificity, and the genotype representing isolates from Cyprinus carpio L. was the most common and diverse form within the species B. acheilognathi.

Differential expression and characterization analysis of a new gene with WD domains in fish oogenesis

A new gene with WD domains is cloned and characterized according to its differential transcription and expression between previtellogenic oocytes (phase I oocytes) and fully-grown oocytes (phase V oocytes) from natural gynogenetic silver crucian carp (Carassius auratus gibelio) by using the combinative methods of suppressive subtraction hybridization, SMART cDNA synthesis and RACE-PCR. The full-length cDNA is 1870 bp. Its 5 ' untranslated region is 210 bp, followed by an open reading frame of 990 bp, which has the typical vertebrate initiator codon of ANNATG. The open reading frame encodes a protein with 329 amino acids. It has 670 bp of 3 ' untranslated region and an AATAAA polyadenylation signal. Because it has 92% homology to STRAP (serine-threonine kinase receptor-associated protein), a recently reported gene, we named it FSTRAP (fish STRAP). Virtual Northern blotting indicated that the FSTRAP was transcribed in fully-grown oocytes (phase V oocytes), but not in previtellogenic oocytes (phase I oocytes). RT-PCR analysis showed that FSTRAP was transcribed in brain, heart, kidney, muscle, ovary, spleen and testis, but not in liver. And its mRNA could be detected in the oocytes from phase II to phase V. Western blotting also showed that FSTRAP protein could be detected in brain, heart, kidney, muscle, ovary, spleen and testis except liver. Results of Western blotting on various oocytes were also similar to the RT-PCR data. FSTRAP protein was not expressed in the previtellogenic oocytes. Its expression initiated from phase II oocytes after vitellogenesis, and was consistent with the mRNA transcription.

Temperature quenching mechanisms for photoluminescence of MBE-grown chlorine-doped ZnSe epilayers

We report on a detailed investigation on the temperature-dependent behavior of photoluminescence from molecular beam epitaxy (MBE)-grown chlorine-doped ZnSe epilayers. The overwhelming neutral donor bound exciton ((ClX)-X-0) emission at 2.797 eV near the band edge with a full-width at half-maximum (FWHM) of similar to 13 meV reveals the high crystalline quality of the samples used. In our experiments, the quick quenching of the (ClX)-X-0 line above 200 K is mainly due to the presence of a nonradiative center with a thermal activation energy of similar to 90 meV, The same activation energy and similar quenching tendency of the (ClX)-X-0 line and the I-3 line at 2.713 eV indicate that they originate from the same physical mechanism. We demonstrate for the first time that the dominant decrease of the integrated intensity of the I, line is due to the thermal excitation of the "I-3 center"-bound excitons to its free exciton states, leaving the "I-3 centers" as efficient nonradiative centers. The optical performance of ZnSe materials is expected to be greatly improved if the density of the "I-3 center" can be controlled. The decrease in the luminescence intensity at moderately low temperature (30-200 K) of the (ClX)-X-0 line is due to the thermal activation of neutral-donor-bound excitons ((ClX)-X-0) to free excitons. (C) 2000 Published by Elsevier Science B.V.