In cultivated rice ( Oryza sativa L.), F-1 pollen sterility is controlled by at least 6 loci of the F, pollen sterility genes. To map S-b, one of loci, rice variety Taichung 65 (T65) carrying S-b(j)/S-b(j) and its nea...In cultivated rice ( Oryza sativa L.), F-1 pollen sterility is controlled by at least 6 loci of the F, pollen sterility genes. To map S-b, one of loci, rice variety Taichung 65 (T65) carrying S-b(j)/S-b(j) and its near-isogenic line TIST2 carrying S-b(i)/S-b(i) were used to develop the mapping population. One hundred and fifty-eight microsatellite markers were selected to survey T65 and TISL2. RM13 on chromosome 5 was found to be polymorphic between them. Cosegregation indicated that RM13 was closely linked with locus S-b. Eleven RFLP markers were selected on the corresponding region from the genetic map of Rice Genome Research Program (RGP) of Japan to convert into sequence-tagged site (STS) markers. Amplicon length polymorphism (ALP) was carried out, but none of them was found to be polymorphic between T65 and TISL2. Then PCR-based RFLP (PBR) was done using six 4-nucleotide recognizing restriction endonucleases. Polymorphism was detected when PCR products of R830STS and R2213SSTS were digested with Taq I. Genetic analysis indicated that the distance between locus S-b and markers, R830STS, RM13 and R2213SSTS were 3.3 cM (centi-Morgan), 5.2 cM and 5.5 cM, respectively. These PCR-based markers could be directly used in marker-assisted selection. The technical system combining genetic mapping and PCR-based marker-assisted selection will facilitate the development of molecular breeding.展开更多
Time series analysis plays an important role in hydrologic forecasting,while the key to this analysis is to establish a proper model.This paper presents a time series neural network model with back propagation proced...Time series analysis plays an important role in hydrologic forecasting,while the key to this analysis is to establish a proper model.This paper presents a time series neural network model with back propagation procedure for hydrologic forecasting.Free from the disadvantages of previous models,the model can be parallel to operate information flexibly and rapidly.It excels in the ability of nonlinear mapping and can learn and adjust by itself,which gives the model a possibility to describe the complex nonlinear hydrologic process.By using directly a training process based on a set of previous data, the model can forecast the time series of stream flow.Moreover,two practical examples were used to test the performance of the time series neural network model.Results confirm that the model is efficient and feasible.展开更多
A new method uses a linear array that takes advantage of underwater physical sound fields to estimate the velocity of an underwater moving target. The mathematical model was established by considering the geometric re...A new method uses a linear array that takes advantage of underwater physical sound fields to estimate the velocity of an underwater moving target. The mathematical model was established by considering the geometric relationship between the moving target installed with only two transducers to radiate sound of different frequencies and the linear array. In addition, deterministic maximum likelihood and signal phase matching algorithms were introduced to effectively find the directions of arrival (DOAs) of the sound sources of the two transducers installed on the target. Factors causing velocity measurement errors were considered. To track the target, a linear array with a compass, a pressure transducer, a signal conditioner and a digital recorder was configured. Relevant requirements for the array parameters were derived. The simulation showed that a 16-element array with an aperture of less than lm can measure velocity with relative error of no more', than 4% when including typical system errors. Anechoic pool and reservoir experiments confirmed these results.展开更多
In order to isolate the total cDNA of rice (Oryza sativa L.) epsps gene, RT-PCR was carried out with template of rice first-strand cDNA and primers designed according to rice EPSP synthase genomic sequence obtained in...In order to isolate the total cDNA of rice (Oryza sativa L.) epsps gene, RT-PCR was carried out with template of rice first-strand cDNA and primers designed according to rice EPSP synthase genomic sequence obtained in previous study. A 1 585-bp cDNA fragment was amplified and cloned. The 1 585-bp cDNA contains an open reading frame (ORF) comprising of 1 533 nucleotides (nt) which encodes a 511 residue polypepetides, including 67 amino acids chloroplast transit peptide and 444 amino acids EPSP synthase mature peptide. A comparison between the EPSP synthase of different sources indicates that the mature peptide shows more than 51% identity except for the fungi EPSP synthase and the transit peptide shows considerably less sequence conservation. The copy number of rice epsps gene is estimated to be one copy per haploid rice genome using southern blot. RT-PCR indicated that rice epsps gene is expressed in rice leaves, endosperms and roots and has the highest expression level in leaves.展开更多
Segmental duplications on rice (Oryza sativa L.) chromosomes 8, 9, 11, and 12 were studied by examining the distributions of sequences resolved by 13 probes detecting multiple copies of DNA sequences. Four of the hyb...Segmental duplications on rice (Oryza sativa L.) chromosomes 8, 9, 11, and 12 were studied by examining the distributions of sequences resolved by 13 probes detecting multiple copies of DNA sequences. Four of the hybridization bands detected by a repetitive sequence probe, rTRS, were mapped to the ends of all the four chromosomes. Two or three of the bands detected by each of the other 12 probes were also mapped to different chromosomes. The bands detected by the same probe usually occurred in similar locations of different chromosomes. Loci detected by different DNA probes were often similarly arranged on different chromosomes. Chromosomes 8 and 9 showed colinearity of marker loci arrangement indicating a possible common origin. A segment on chromosome 9 was also very similar to the previously reported duplicated fragments on the ends of chromosomes 11 and 12 which were also detected in this study, indicating a likely common origin. Moreover, the various degrees of distributional similarity of the segments suggest a complex relationship among the chromosomes in the evolution of the rice genome. These results support the proposition that chromosome duplication and diversification may be a mechanism for the origin and evolution of the chromosomes in the rice genome.展开更多
Alternative splicing is a major contributor to genomic complexity and proteome diversity, yet the analysis of alternative splicing for the sequence containing nucleotide binding site and leucine-rich repeats (NBS-LRR...Alternative splicing is a major contributor to genomic complexity and proteome diversity, yet the analysis of alternative splicing for the sequence containing nucleotide binding site and leucine-rich repeats (NBS-LRR) domain has not been explored in rice (Oryza sativa L.). Hidden Markov model (HMM) searches were performed for NBS-LRR domain. 875 NBS-LRR-encoding sequences were obtained from the Institute for Genomic Research (TIGR). All of them were used to blast Knowledge-based Oryza Molecular Biological Encyclopaedia (KOME), TIGR rice gene index (TGI), and Universal Protein Resource (UniProt) to obtain homologous full-length cDNAs (FL-cDNAs), tentative consensus sequences, and protein sequences. Alternative splicing events were detected from genomic alignment of FL-cDNAs, tentative consensus sequences, and protein sequences, which provide valuable information on splice variants of genes. These sequences were aligned to the corresponding BAC sequences using the Spidey and Sim4 programs and each of the proteins was aligned by tBLASTn. Of the 875 NBS-LRR sequences, 119 (13.6%) sequences had alternative splicing where multiple FL-cDNAs, TGI sequences and proteins corresponded to the same gene. 71 intron retention events, 20 exon skipping events, 16 alternative termination events, 25 alternative initiation events, 12 alternative 5' splicing events, and 16 alternative 3' splicing events were identified. Most of these alternative splices were supported by two or more transcripts. The data sets are available at http://www.bioinfor.org. Furthermore, the bioinformatics analysis of splice boundaries showed that exon skipping and intron retention did not exhibit strong consensus. This implies a different regulation mechanism that guides the expression of splice isoforms. This article also presents the analysis of the effects of intron retention on proteins. The C-terminal regions of alternative proteins turned out to be more variable than the N-terminal regions. Finally, tissue distribution and protein localization of alternative splicing were explored. The largest categories of tissue distributions for alternative splicing were shoot and callus. More than one-thirds of protein localization for splice forms was plasma membrane and cytoplasm. All the NBS-LRR proteins for splice forms may have important function in disease resistance and activate downstream signaling pathways.展开更多
The reorientation of microtubules (MTS) in roots of Oryza sativa L. treated with 2,4_D was studied using confocal laser scanning microscopy. In the control (the roots were not treated with 2,4_D), different distributi...The reorientation of microtubules (MTS) in roots of Oryza sativa L. treated with 2,4_D was studied using confocal laser scanning microscopy. In the control (the roots were not treated with 2,4_D), different distribution patterns of MTS were observed in the different growth zones of root tips. MTS of the cortical cells were randomly aligned in the zone of cell division. They were transversely arranged in the cortical cells of the zone of cell elongation; and obliquely oriented in the root hair zone. After treatment with 2,4_D, MTS displayed distinct changes with reorientation in the cortex of the root tip coupling with the inhibition of root growth. MTS changed their orientation in the cortical cells of the zone of cell division from being randomly oriented to transversely oriented when incubated in 1 mg/L 2,4_D for 1 h. However, they were recovered and became randomly oriented when the roots were treated with 1 mg/L 2,4_D for 24 h. An array of MTS, which was different from that in the control, was observed in the cortical cells of the zone of cell elongation in the roots treated with 1 mg/L 2,4_D for 1 h. After treatment with 10 mg/L 2,4_D for 1 h, the MTS in the cortical cells of the zone of cell division became transversely reorientated, but the pattern of MTS distribution was different from that in the 1_hour treatment of 1 mg/L 2,4_D. MTS were hardly detected in the same type of cells when roots were submerged in 10 mg/L 2,4_D for 24 h. When roots were incubated in 10 mg/L 2,4_D for 1 h, the MTS of the cortical cells in the zone of cell elongation became randomly oriented, and much more randomly when the roots were treated for 24 h.展开更多
Eutrophication or the process of nutrient enrichment of stagnant waters due to excessive use of fertilizer is becoming a critical issue worldwide. Lake Gregory, an artificial lake situated in Nuwara Eliya, Sri Lanka w...Eutrophication or the process of nutrient enrichment of stagnant waters due to excessive use of fertilizer is becoming a critical issue worldwide. Lake Gregory, an artificial lake situated in Nuwara Eliya, Sri Lanka was once a very attractive landscape feature and recreational area attracting a large number of visitors. Rapid urbanization in surrounding areas and the consequent intensification of agricultural and industrial activities led to eutrophication and siltation in the lake. Present study was conducted to detect cyanobacterial diversity and their ability to produce hepatotoxic microcystins using polymerase chain reaction (PCR)-based techniques. Twenty five water samples (surface and bottom) were collected from the lake and total nitrogen and total carbon were estimated. Cyanobacterial cultures were grown in appropriate media and microscopic observations were used to determine the morphological diversity of cyanobacteria isolated from different sites. Genomic DNA was isolated and purified from cyanobacteria using Boom's method. DNA samples were analyzed by PCR with oligonucleotide primers for 16S rRNA gene and mcyA gene of the operon that encodes a microcystin synthetase. The 16S rRNA gene sequences revealed the presences of cyanobacteria belong to Synechococcus sp., Microcystis aeruginosa, Calothrix sp., Leptolyngbya sp., Limnothrix sp., order Oscillatoriales and order Chroococcales. The sequences obtained from this study were deposited in the database under the accession numbers (GenBank: GU368104-GU368116). PCR amplification of mcyA primers indicated the potential for toxin formation of isolated M. aeruginosa from Lake Gregory. This preliminary study shows that the Lake Gregory is under the potential risk of cyanobacterial toxicity. Clearly more work is needed to extend this finding and clarify if other cyanobacterial isolates have genetic potential to produce microcystin since this lake is utilized for recreational activities.展开更多
Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microsco...Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microscope(SEM),transmission electron microscope(TEM),dispersive X-ray spectrometer(EDS)and selected area electron diffraction(SAED)techniques.t-NdVO4 nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm,which grow orientally along the direction of(112)crystalline plane and self-assemble to form nanorod-arrays.The results show that Eu^3+-doping interrupts the formation of NdVO4 nanorod-arrays,and then leads to the red-shift of the strongest luminescence emission of Nd3+transition from 4D3/2 state to 4I11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply.The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.展开更多
A superimposed training (ST) based channel estimation method is presented that provides accurate estimation of a sparse underwater acoustic orthogonal frequency-division multiplexing (OFDM) channel while improving...A superimposed training (ST) based channel estimation method is presented that provides accurate estimation of a sparse underwater acoustic orthogonal frequency-division multiplexing (OFDM) channel while improving bandwidth transmission efficiency. A periodic low power training sequence is superimposed on the information sequence at the transmitter. The channel parameters can be estimated without consuming any extra system bandwidth, but an unknown information sequence can interfere with the ST channel estimation method, so in this paper, an iterative method was adopted to improve estimation performance. An underwater acoustic channel's properties include large channel dimensions and a sparse structure, so a matching pursuit (MP) algorithm was used to estimate the nonzero taps, allowing the performance loss caused by additive white Gaussian noise (AWGN) to be reduced. The results of computer simulations show that the proposed method has good channel estimation performance and can reduce the peak-to-average ratio of the OFDM channel as well.展开更多
Common carp expressed sequence tags (ESTs) were analyzed for the existence of microsatellites, or simple sequence repeats (SSRs). In the NCBI dbEST database, a total of 10612 sequences were registered before Decem...Common carp expressed sequence tags (ESTs) were analyzed for the existence of microsatellites, or simple sequence repeats (SSRs). In the NCBI dbEST database, a total of 10612 sequences were registered before December 31, 2004. A complete search of 2-6 nucleotide microsatellites resulted in the identification of 513 SSR-containing ESTs, accounting for 4.8% of the total. Cluster analysis indicated that 73 sequences of SSR-containing ESTs fell into 27 groups and the remaining 440 ESTs were independent. A total of 467 unique SSR-containing ESTs were identified. These EST-SSRs contained a vari- ety of simple sequence types, and di- and tri-nucleotide repeats were the most abundant, accounting for 42.1% and 27.9% of the whole, respectively. Of the dinucleotide repeats, CA/TG was the most abundant, followed by GA/TC. BLASTx search showed that 38.1% of the SSR loci could be associated with genes or proteins of known or unknown function. BLASTx searches of SSR-containing ESTs also showed high frequencies (98/179) of hits on zebrafish sequences.展开更多
A laboratory-scale anaerobic sequencing batch reactor (ASBR) was used to pretreat coking wastewater. Inoculated anaerobic granular biomass was acclimated for 225 d to the coking wastewater, and then the biochemical me...A laboratory-scale anaerobic sequencing batch reactor (ASBR) was used to pretreat coking wastewater. Inoculated anaerobic granular biomass was acclimated for 225 d to the coking wastewater, and then the biochemical methane potential (BMP)of the coking wastewater in the acclimated granular biomass was measured. At the same time, some fundamental technological factors, such as the filling time and the reacting time ratio (tf/tr), the mixing intensity and the intermittent mixing mode, that affect anaerobic pretreatment of coking wastewater with ASBR, were evaluated through orthogonal tests. The COD removal efficiency reached 38%~50% in the stable operation period with the organic loading rate of 0.37~0.54 kg COD/(m3.d) at the optimum conditions of tf/tr, the mixing intensity and the intermittent mixing mode. In addition, the biodegradability of coking wastewater distinctly increased after the pretreatment using ASBR. At the end of the experiment, the microorganism forms on the granulated sludge in the ASBR were observed using SEM (scanning electron microscope) and fluoroscope. The results showed that the dominant microorganism on the granular sludge was Methanosaeta instead of Methanosarcina dominated on the inoculated sludge.展开更多
[Objective] This study aimed to analyze the cause of the generation of short-term heavy precipitations in a regional heavy rainstorm in Shannxi Province. [Method] Taking a heavy rainstorm covering most parts of Shaanx...[Objective] This study aimed to analyze the cause of the generation of short-term heavy precipitations in a regional heavy rainstorm in Shannxi Province. [Method] Taking a heavy rainstorm covering most parts of Shaanxi Province in late July 2010 as an example, data of five Doppler weather radars in Shaanxi Province were employed for a detailed analysis of the evolution of the heavy rainstorm pro- cess. [Result] Besides the good large-scale weather background conditions, the de- velopment and evolution of some mesoscale and small-scale weather systems direct- ly led to short-term heavy precipitations during the heavy rainstorm process, involv- ing the intrusion of moderate IS-scale weak cold air and presence of small-scale wind shear, convergence and adverse wind area. In addition, small-scale convection echoes were arranged in lines and formed a "train effect", which would also con- tribute to the generation of short-term heavy precipitation. [Conclusion] This study provided basic information for more clear and in-depth analysis of the formation mechanism of short-term heavy precipitations.展开更多
文摘In cultivated rice ( Oryza sativa L.), F-1 pollen sterility is controlled by at least 6 loci of the F, pollen sterility genes. To map S-b, one of loci, rice variety Taichung 65 (T65) carrying S-b(j)/S-b(j) and its near-isogenic line TIST2 carrying S-b(i)/S-b(i) were used to develop the mapping population. One hundred and fifty-eight microsatellite markers were selected to survey T65 and TISL2. RM13 on chromosome 5 was found to be polymorphic between them. Cosegregation indicated that RM13 was closely linked with locus S-b. Eleven RFLP markers were selected on the corresponding region from the genetic map of Rice Genome Research Program (RGP) of Japan to convert into sequence-tagged site (STS) markers. Amplicon length polymorphism (ALP) was carried out, but none of them was found to be polymorphic between T65 and TISL2. Then PCR-based RFLP (PBR) was done using six 4-nucleotide recognizing restriction endonucleases. Polymorphism was detected when PCR products of R830STS and R2213SSTS were digested with Taq I. Genetic analysis indicated that the distance between locus S-b and markers, R830STS, RM13 and R2213SSTS were 3.3 cM (centi-Morgan), 5.2 cM and 5.5 cM, respectively. These PCR-based markers could be directly used in marker-assisted selection. The technical system combining genetic mapping and PCR-based marker-assisted selection will facilitate the development of molecular breeding.
文摘Time series analysis plays an important role in hydrologic forecasting,while the key to this analysis is to establish a proper model.This paper presents a time series neural network model with back propagation procedure for hydrologic forecasting.Free from the disadvantages of previous models,the model can be parallel to operate information flexibly and rapidly.It excels in the ability of nonlinear mapping and can learn and adjust by itself,which gives the model a possibility to describe the complex nonlinear hydrologic process.By using directly a training process based on a set of previous data, the model can forecast the time series of stream flow.Moreover,two practical examples were used to test the performance of the time series neural network model.Results confirm that the model is efficient and feasible.
基金Supported by the National Science Foundation of China under Grant No.60672136
文摘A new method uses a linear array that takes advantage of underwater physical sound fields to estimate the velocity of an underwater moving target. The mathematical model was established by considering the geometric relationship between the moving target installed with only two transducers to radiate sound of different frequencies and the linear array. In addition, deterministic maximum likelihood and signal phase matching algorithms were introduced to effectively find the directions of arrival (DOAs) of the sound sources of the two transducers installed on the target. Factors causing velocity measurement errors were considered. To track the target, a linear array with a compass, a pressure transducer, a signal conditioner and a digital recorder was configured. Relevant requirements for the array parameters were derived. The simulation showed that a 16-element array with an aperture of less than lm can measure velocity with relative error of no more', than 4% when including typical system errors. Anechoic pool and reservoir experiments confirmed these results.
文摘In order to isolate the total cDNA of rice (Oryza sativa L.) epsps gene, RT-PCR was carried out with template of rice first-strand cDNA and primers designed according to rice EPSP synthase genomic sequence obtained in previous study. A 1 585-bp cDNA fragment was amplified and cloned. The 1 585-bp cDNA contains an open reading frame (ORF) comprising of 1 533 nucleotides (nt) which encodes a 511 residue polypepetides, including 67 amino acids chloroplast transit peptide and 444 amino acids EPSP synthase mature peptide. A comparison between the EPSP synthase of different sources indicates that the mature peptide shows more than 51% identity except for the fungi EPSP synthase and the transit peptide shows considerably less sequence conservation. The copy number of rice epsps gene is estimated to be one copy per haploid rice genome using southern blot. RT-PCR indicated that rice epsps gene is expressed in rice leaves, endosperms and roots and has the highest expression level in leaves.
文摘Segmental duplications on rice (Oryza sativa L.) chromosomes 8, 9, 11, and 12 were studied by examining the distributions of sequences resolved by 13 probes detecting multiple copies of DNA sequences. Four of the hybridization bands detected by a repetitive sequence probe, rTRS, were mapped to the ends of all the four chromosomes. Two or three of the bands detected by each of the other 12 probes were also mapped to different chromosomes. The bands detected by the same probe usually occurred in similar locations of different chromosomes. Loci detected by different DNA probes were often similarly arranged on different chromosomes. Chromosomes 8 and 9 showed colinearity of marker loci arrangement indicating a possible common origin. A segment on chromosome 9 was also very similar to the previously reported duplicated fragments on the ends of chromosomes 11 and 12 which were also detected in this study, indicating a likely common origin. Moreover, the various degrees of distributional similarity of the segments suggest a complex relationship among the chromosomes in the evolution of the rice genome. These results support the proposition that chromosome duplication and diversification may be a mechanism for the origin and evolution of the chromosomes in the rice genome.
基金This work was supported by Natural Sciences Foundation of Guangdong Province (No. 0409078)Natural Sciences Foundation from the Education Department of Guangdong Province (No. z02051).
文摘Alternative splicing is a major contributor to genomic complexity and proteome diversity, yet the analysis of alternative splicing for the sequence containing nucleotide binding site and leucine-rich repeats (NBS-LRR) domain has not been explored in rice (Oryza sativa L.). Hidden Markov model (HMM) searches were performed for NBS-LRR domain. 875 NBS-LRR-encoding sequences were obtained from the Institute for Genomic Research (TIGR). All of them were used to blast Knowledge-based Oryza Molecular Biological Encyclopaedia (KOME), TIGR rice gene index (TGI), and Universal Protein Resource (UniProt) to obtain homologous full-length cDNAs (FL-cDNAs), tentative consensus sequences, and protein sequences. Alternative splicing events were detected from genomic alignment of FL-cDNAs, tentative consensus sequences, and protein sequences, which provide valuable information on splice variants of genes. These sequences were aligned to the corresponding BAC sequences using the Spidey and Sim4 programs and each of the proteins was aligned by tBLASTn. Of the 875 NBS-LRR sequences, 119 (13.6%) sequences had alternative splicing where multiple FL-cDNAs, TGI sequences and proteins corresponded to the same gene. 71 intron retention events, 20 exon skipping events, 16 alternative termination events, 25 alternative initiation events, 12 alternative 5' splicing events, and 16 alternative 3' splicing events were identified. Most of these alternative splices were supported by two or more transcripts. The data sets are available at http://www.bioinfor.org. Furthermore, the bioinformatics analysis of splice boundaries showed that exon skipping and intron retention did not exhibit strong consensus. This implies a different regulation mechanism that guides the expression of splice isoforms. This article also presents the analysis of the effects of intron retention on proteins. The C-terminal regions of alternative proteins turned out to be more variable than the N-terminal regions. Finally, tissue distribution and protein localization of alternative splicing were explored. The largest categories of tissue distributions for alternative splicing were shoot and callus. More than one-thirds of protein localization for splice forms was plasma membrane and cytoplasm. All the NBS-LRR proteins for splice forms may have important function in disease resistance and activate downstream signaling pathways.
文摘The reorientation of microtubules (MTS) in roots of Oryza sativa L. treated with 2,4_D was studied using confocal laser scanning microscopy. In the control (the roots were not treated with 2,4_D), different distribution patterns of MTS were observed in the different growth zones of root tips. MTS of the cortical cells were randomly aligned in the zone of cell division. They were transversely arranged in the cortical cells of the zone of cell elongation; and obliquely oriented in the root hair zone. After treatment with 2,4_D, MTS displayed distinct changes with reorientation in the cortex of the root tip coupling with the inhibition of root growth. MTS changed their orientation in the cortical cells of the zone of cell division from being randomly oriented to transversely oriented when incubated in 1 mg/L 2,4_D for 1 h. However, they were recovered and became randomly oriented when the roots were treated with 1 mg/L 2,4_D for 24 h. An array of MTS, which was different from that in the control, was observed in the cortical cells of the zone of cell elongation in the roots treated with 1 mg/L 2,4_D for 1 h. After treatment with 10 mg/L 2,4_D for 1 h, the MTS in the cortical cells of the zone of cell division became transversely reorientated, but the pattern of MTS distribution was different from that in the 1_hour treatment of 1 mg/L 2,4_D. MTS were hardly detected in the same type of cells when roots were submerged in 10 mg/L 2,4_D for 24 h. When roots were incubated in 10 mg/L 2,4_D for 1 h, the MTS of the cortical cells in the zone of cell elongation became randomly oriented, and much more randomly when the roots were treated for 24 h.
文摘Eutrophication or the process of nutrient enrichment of stagnant waters due to excessive use of fertilizer is becoming a critical issue worldwide. Lake Gregory, an artificial lake situated in Nuwara Eliya, Sri Lanka was once a very attractive landscape feature and recreational area attracting a large number of visitors. Rapid urbanization in surrounding areas and the consequent intensification of agricultural and industrial activities led to eutrophication and siltation in the lake. Present study was conducted to detect cyanobacterial diversity and their ability to produce hepatotoxic microcystins using polymerase chain reaction (PCR)-based techniques. Twenty five water samples (surface and bottom) were collected from the lake and total nitrogen and total carbon were estimated. Cyanobacterial cultures were grown in appropriate media and microscopic observations were used to determine the morphological diversity of cyanobacteria isolated from different sites. Genomic DNA was isolated and purified from cyanobacteria using Boom's method. DNA samples were analyzed by PCR with oligonucleotide primers for 16S rRNA gene and mcyA gene of the operon that encodes a microcystin synthetase. The 16S rRNA gene sequences revealed the presences of cyanobacteria belong to Synechococcus sp., Microcystis aeruginosa, Calothrix sp., Leptolyngbya sp., Limnothrix sp., order Oscillatoriales and order Chroococcales. The sequences obtained from this study were deposited in the database under the accession numbers (GenBank: GU368104-GU368116). PCR amplification of mcyA primers indicated the potential for toxin formation of isolated M. aeruginosa from Lake Gregory. This preliminary study shows that the Lake Gregory is under the potential risk of cyanobacterial toxicity. Clearly more work is needed to extend this finding and clarify if other cyanobacterial isolates have genetic potential to produce microcystin since this lake is utilized for recreational activities.
基金Project(51202066)supported by the National Natural Science Foundation of ChinaProject(NCET-13-0784)supported by the Program for New Century Excellent Talents of the Education Ministry,China。
文摘Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microscope(SEM),transmission electron microscope(TEM),dispersive X-ray spectrometer(EDS)and selected area electron diffraction(SAED)techniques.t-NdVO4 nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm,which grow orientally along the direction of(112)crystalline plane and self-assemble to form nanorod-arrays.The results show that Eu^3+-doping interrupts the formation of NdVO4 nanorod-arrays,and then leads to the red-shift of the strongest luminescence emission of Nd3+transition from 4D3/2 state to 4I11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply.The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.
基金Supported by the National Natural Science Foundation of China under Grant No.60572039
文摘A superimposed training (ST) based channel estimation method is presented that provides accurate estimation of a sparse underwater acoustic orthogonal frequency-division multiplexing (OFDM) channel while improving bandwidth transmission efficiency. A periodic low power training sequence is superimposed on the information sequence at the transmitter. The channel parameters can be estimated without consuming any extra system bandwidth, but an unknown information sequence can interfere with the ST channel estimation method, so in this paper, an iterative method was adopted to improve estimation performance. An underwater acoustic channel's properties include large channel dimensions and a sparse structure, so a matching pursuit (MP) algorithm was used to estimate the nonzero taps, allowing the performance loss caused by additive white Gaussian noise (AWGN) to be reduced. The results of computer simulations show that the proposed method has good channel estimation performance and can reduce the peak-to-average ratio of the OFDM channel as well.
文摘Common carp expressed sequence tags (ESTs) were analyzed for the existence of microsatellites, or simple sequence repeats (SSRs). In the NCBI dbEST database, a total of 10612 sequences were registered before December 31, 2004. A complete search of 2-6 nucleotide microsatellites resulted in the identification of 513 SSR-containing ESTs, accounting for 4.8% of the total. Cluster analysis indicated that 73 sequences of SSR-containing ESTs fell into 27 groups and the remaining 440 ESTs were independent. A total of 467 unique SSR-containing ESTs were identified. These EST-SSRs contained a vari- ety of simple sequence types, and di- and tri-nucleotide repeats were the most abundant, accounting for 42.1% and 27.9% of the whole, respectively. Of the dinucleotide repeats, CA/TG was the most abundant, followed by GA/TC. BLASTx search showed that 38.1% of the SSR loci could be associated with genes or proteins of known or unknown function. BLASTx searches of SSR-containing ESTs also showed high frequencies (98/179) of hits on zebrafish sequences.
基金Project (No. 40272108) supported by the National Natural Science Foundation of China
文摘A laboratory-scale anaerobic sequencing batch reactor (ASBR) was used to pretreat coking wastewater. Inoculated anaerobic granular biomass was acclimated for 225 d to the coking wastewater, and then the biochemical methane potential (BMP)of the coking wastewater in the acclimated granular biomass was measured. At the same time, some fundamental technological factors, such as the filling time and the reacting time ratio (tf/tr), the mixing intensity and the intermittent mixing mode, that affect anaerobic pretreatment of coking wastewater with ASBR, were evaluated through orthogonal tests. The COD removal efficiency reached 38%~50% in the stable operation period with the organic loading rate of 0.37~0.54 kg COD/(m3.d) at the optimum conditions of tf/tr, the mixing intensity and the intermittent mixing mode. In addition, the biodegradability of coking wastewater distinctly increased after the pretreatment using ASBR. At the end of the experiment, the microorganism forms on the granulated sludge in the ASBR were observed using SEM (scanning electron microscope) and fluoroscope. The results showed that the dominant microorganism on the granular sludge was Methanosaeta instead of Methanosarcina dominated on the inoculated sludge.
基金Supported by Special Fund for National Weather Service Forecaster of China (CMAYBY2011-050)~~
文摘[Objective] This study aimed to analyze the cause of the generation of short-term heavy precipitations in a regional heavy rainstorm in Shannxi Province. [Method] Taking a heavy rainstorm covering most parts of Shaanxi Province in late July 2010 as an example, data of five Doppler weather radars in Shaanxi Province were employed for a detailed analysis of the evolution of the heavy rainstorm pro- cess. [Result] Besides the good large-scale weather background conditions, the de- velopment and evolution of some mesoscale and small-scale weather systems direct- ly led to short-term heavy precipitations during the heavy rainstorm process, involv- ing the intrusion of moderate IS-scale weak cold air and presence of small-scale wind shear, convergence and adverse wind area. In addition, small-scale convection echoes were arranged in lines and formed a "train effect", which would also con- tribute to the generation of short-term heavy precipitation. [Conclusion] This study provided basic information for more clear and in-depth analysis of the formation mechanism of short-term heavy precipitations.