Falcaria vulgaris (sickleweed) is native to Eurasia and a potential invasive plant of the United States. No molecular markers have been developed so far for sickleweed. Characterization of molecular markers for this p...Falcaria vulgaris (sickleweed) is native to Eurasia and a potential invasive plant of the United States. No molecular markers have been developed so far for sickleweed. Characterization of molecular markers for this plant would allow investigation into its population structure and biogeography thereby yielding insights into risk analysis and effective management practices of the plant. In order to characterize the molecular markers, DNA samples were collected from eight populations in Iowa, Nebraska and South Dakota. Nuclear microsatellite markers developed for other Apiaceae taxa were screened and tested for intergeneric transferability to sickleweed. The chloroplast trnL intron and trnL-F intergenic spacer regions were sequenced and the sequences were used to design primers to amplify the microsatellites present within each region. We characterized eight polymorphic microsatellite markers for sickleweed that included six nuclear and two chloroplast markers. Our result showed intergeneric transferability of six nuclear microsatellite markers from Daucus carota to F. vulgaris. The markers we characterized are useful for population genetic study of F. vulgaris.展开更多
Active carbons(ACs) were prepared through chemical activation of biochar from whole corn stalk(WCS)and corn stalk pith(CSP) at varying temperatures using potassium hydroxide as the activating agent. ACs were character...Active carbons(ACs) were prepared through chemical activation of biochar from whole corn stalk(WCS)and corn stalk pith(CSP) at varying temperatures using potassium hydroxide as the activating agent. ACs were characterized via pore structural analysis and scanning electron microscopy(SEM). These adsorbents were then assessed for their adsorption capacity for butanol vapor. It was found that WCS activated at900 °C for 1 h(WCS-900) had optimal butanol adsorption characteristics. The BET surface area and total pore volume of the WCS-900 were 2330 m2/g and 1.29 cm3/g, respectively. The dynamic adsorption capacity of butanol vapor was 410.0 mg/g, a 185.1% increase compared to charcoal-based commercial AC(143.8 mg/g).展开更多
Dear Editor,Viruses are intracellular parasites that depend on cellular components to replicate.Viruses communicate withthe cellular machinery through protein–protein interactions(PPIs),for which each individual viru...Dear Editor,Viruses are intracellular parasites that depend on cellular components to replicate.Viruses communicate withthe cellular machinery through protein–protein interactions(PPIs),for which each individual virus encodes aunique array of proteins.Each viral protein is capable ofindependently interacting with multiple cellular展开更多
Although shifts in life-history traits of insular vertebrates, as compared with mainland populations, have been observed in many taxa, few studies have examined the relationships among individual life-history traits o...Although shifts in life-history traits of insular vertebrates, as compared with mainland populations, have been observed in many taxa, few studies have examined the relationships among individual life-history traits on islands. Lifehistory theory also predicts that there is a trade-off between body size and reproductive effort, and between egg size and clutch size. We surveyed the rice frog, Fejervarya limnocharis, on 20 islands within the Zhoushan Archipelago and two nearby sites on the mainland of China to compare differences in life-history traits and to explore relationships among those traits. Rice frog females reached a greater body size on half of the smaller islands among the total 20 surveyed islands, and larger egg size, decreased clutch size and reduced reproductive effort on most of the islands when compared to the two mainland sites. Insular body size was negatively correlated with reproductive effort. There was a negative correlation between egg size and clutch size. Results suggest that life-history theory provides a good explanation for co-variation between body size and reproductive effort, and between egg size and clutch size in rice frogs on the islands.展开更多
为了研究湿度梯度对根系向水性反应的影响,采用Takahashi and Scott于1993年创建的方法,设置以下3个试验:1)向水性诱导物不同倾斜角试验;2)根系距向水性诱导物不同距离试验;3)根尖距底部饱和K2CO3溶液不同距离试验。同时,还研究了根长...为了研究湿度梯度对根系向水性反应的影响,采用Takahashi and Scott于1993年创建的方法,设置以下3个试验:1)向水性诱导物不同倾斜角试验;2)根系距向水性诱导物不同距离试验;3)根尖距底部饱和K2CO3溶液不同距离试验。同时,还研究了根长和根系延伸速率对根系向水性弯曲的影响。结果表明,用饱和K2CO3溶液控制湿度时根系的向水性弯曲度明显大于纯水。随着诱导物倾斜角的增大,向水性弯曲增强。与距诱导物3 mm和6 mm相比,根系直接接触诱导物时表现出最大的向水性反应。与根尖距底部盐溶液6 cm相比,相距4 cm时向水性弯曲度增大,这些与根尖周围的湿度梯度增大有关。当根长为1.0、1.5、2.0、2.5、3.0 cm时,短根比长根表现出更大的向水性反应,这可能与其较慢的延伸速率为根系对湿度梯度的反应提供了更充足的时间有关。为了验证这个假说,用相同长度的根系、通过控制不同温度进行试验,结果表明根系的向水性弯曲随温度升高而降低。可见,玉米初生根的向水性反应受环境和根系发育阶段两方面影响。当根系相距诱导物较近、根系周围的湿度梯度较大时,根系向水性反应更强。而且,具有较小延伸速率根系的向水性反应更大。考虑到干旱条件下根系伸长慢、且土壤中湿度梯度大,因而可以认为干旱条件下根系的向水性生长在玉米吸收水分中有重要作用。同时,对根系向水性诱导方法的优化有助于其生理机制的进一步研究。展开更多
The complex genetic architecture of quality traits has hindered efforts to modify seed nutrients in soybean. Genome-wide association studies were conducted for seed composition, including protein, oil, fatty acids, an...The complex genetic architecture of quality traits has hindered efforts to modify seed nutrients in soybean. Genome-wide association studies were conducted for seed composition, including protein, oil, fatty acids, and amino acids, using 313 diverse soybean germplasm accessions genotyped with a high-density SNP array. A total of 87 chromosomal regions were identified to be associated with seed composition, explain- ing 8%-89% of genetic variances. The candidate genes GmSAT1, AK-HSDH, SACPD-C, and FAD3A of known function, and putative MtN21 nodulin, FATB, and steroid-5-^-reductase involved in N2 fixation, amino acid biosynthesis, and fatty acid metabolism were found at the major-effect loci. Further analysis of additional germplasm accessions indicated that these major-effect loci had been subjected to domes- tication or modern breeding selection, and the allelic variants and distributions were relevant to geographic regions. We also revealed that amino acid concentrations related to seed weight and to total protein had a different genetic basis. This helps uncover the in-depth genetic mechanism of the intricate relationships among the seed compounds. Thus, our study not only provides valuable genes and markers for soybean nutrient improvement, both quantitatively and qualitatively, but also offers insights into the alteration of soybean quality during domestication and breeding.展开更多
Biotic and abiotic stress lead to elevated levels of jasmonic acid （JA） and its derivatives and activation of the biosynthesis of nicotine and related pyridine alkaloids in cultivated tobacco （Nicotiana tabacum L....Biotic and abiotic stress lead to elevated levels of jasmonic acid （JA） and its derivatives and activation of the biosynthesis of nicotine and related pyridine alkaloids in cultivated tobacco （Nicotiana tabacum L.）. Among the JA- responsive genes is NtPMTla, encoding putrescine N-methyl transferase, a key regulatory enzyme in nicotine formation. We have characterized three genes （NtMYC2a, b, c） encoding basic helix-loop-helix （bHLH） transcription factors （TFs） whose expression is rapidly induced by JA and that specifically activate JA-inducible NtPMTla expression by binding a G-box motif within the NtPMTla promoter in in vivo and in vitro assays. Using split-YFP assays, we further show that, in the absence of JA, NtMYC2a and NtMYC2b are present as nuclear complexes with the NtJAZ1 repressor. RNA interference （RNAi）-mediated knockdown of NtMYC2a and NtMYC2b expression results in significant decreases in JA-inducible NtPMTla transcript levels, as well as reduced levels of transcripts encoding other enzymes involved in nicotine and minor alkaloid biosynthesis, in- cluding an 80-90% reduction in the level of transcripts encoding the putative nicotine synthase gene NtA662. In contrast, ectopic overexpression of NtMYC2a and NtMYC2b had no effect on NtPMTla expression in the presence or absence of exogenously added JA. These data suggest that NtMYC2a, b, c are required components of JA-inducible expression of multiple genes in the nicotine biosynthetic pathway and may act additively in the activation of JA responses.展开更多
Despite significant advances in antiretroviral therapy,increasing drug resistance and toxicities observed among many of the current approved human immunodeficiency virus(HIV) drugs indicate a need for discovery and de...Despite significant advances in antiretroviral therapy,increasing drug resistance and toxicities observed among many of the current approved human immunodeficiency virus(HIV) drugs indicate a need for discovery and development of potent and safe antivirals with a novel mechanism of action.Maturation inhibitors(MIs) represent one such new class of HIV therapies.MIs inhibit a late step in the HIV-1 Gag processing cascade,causing defective core condensation and the release of non-infectious virus particles from infected cells,thus blocking the spread of the infection to new cells.Clinical proof-ofconcept for the MIs was established with betulinic acid derived bevirimat,the prototype HIV-1 MI.Despite the discontinuation of its further clinical development in 2010 due to a lack of uniform patient response caused by naturally occurring drug resistance Gag polymorphisms,several second-generation MIs with improved activity against viruses exhibiting Gag polymorphism mediated resistance have been recently discovered and are under clinical evaluation in HIV/AID patients.In this review,current understanding of HIV-1 MIs is described and recent progress made toward elucidating the mechanism of action,target identification and development of second-generation MIs is reviewed.展开更多
Doubled haploid （DH） populations are useful to scientists and breeders in both crop improvement and basic research. Current methods of producing DHs usually need in vitro culture for extracting haploids and chemical...Doubled haploid （DH） populations are useful to scientists and breeders in both crop improvement and basic research. Current methods of producing DHs usually need in vitro culture for extracting haploids and chemical treatment for chromosome doubling. This report describes a simple method for synthesizing DHs （SynDH） especially for allopolyploid species by utilizing meiotic restitution genes. The method involves three steps： hybridization to induce recombination, interspecific hybridization to extract haploids, and spontaneous chromosome doubling by selfing the interspecific Fis. DHs produced in this way contain recombinant chromosomes in the genome（s） of interest in a homogeneous background. No special equipment or treatments are involved in the DH production and it can be easily applied in any breeding and/or genetic program. Triticum turgidum L. and Aegilops tauschii Coss, the two ancestral species of common wheat （Triticurn aestivum L.） and molecular markers were used to demonstrate the SynDH method.展开更多
文摘Falcaria vulgaris (sickleweed) is native to Eurasia and a potential invasive plant of the United States. No molecular markers have been developed so far for sickleweed. Characterization of molecular markers for this plant would allow investigation into its population structure and biogeography thereby yielding insights into risk analysis and effective management practices of the plant. In order to characterize the molecular markers, DNA samples were collected from eight populations in Iowa, Nebraska and South Dakota. Nuclear microsatellite markers developed for other Apiaceae taxa were screened and tested for intergeneric transferability to sickleweed. The chloroplast trnL intron and trnL-F intergenic spacer regions were sequenced and the sequences were used to design primers to amplify the microsatellites present within each region. We characterized eight polymorphic microsatellite markers for sickleweed that included six nuclear and two chloroplast markers. Our result showed intergeneric transferability of six nuclear microsatellite markers from Daucus carota to F. vulgaris. The markers we characterized are useful for population genetic study of F. vulgaris.
基金supported by following projects:“Development of high value carbon based adsorbents from thermochemically produced biochar”USDA-NIFA2011-67009-20030 through the USDA-NIFA Agriculture and Food Research Initiative Sustainable Bioenergy Program which funded the Micropore analyzer and instruments for modifying AC+1 种基金NSF EPSCoR TrackⅡDakota Bio Con center(National Science Foundation/EPSCo R Award No.1330842)supported Mr.Cao Yuhe for his PhD study and GC–MS instrumentDOE Sun Grant Concept Project“Developing Gas Stripping-Adsorption/Desorption Separation Processes based on Porous Carbon Adsorbents for Biofuel Purification from Bioreactors”(North Central Sun Grant Award No.1300478)supported upgrading the Chemical Adsorption Analyzer
文摘Active carbons(ACs) were prepared through chemical activation of biochar from whole corn stalk(WCS)and corn stalk pith(CSP) at varying temperatures using potassium hydroxide as the activating agent. ACs were characterized via pore structural analysis and scanning electron microscopy(SEM). These adsorbents were then assessed for their adsorption capacity for butanol vapor. It was found that WCS activated at900 °C for 1 h(WCS-900) had optimal butanol adsorption characteristics. The BET surface area and total pore volume of the WCS-900 were 2330 m2/g and 1.29 cm3/g, respectively. The dynamic adsorption capacity of butanol vapor was 410.0 mg/g, a 185.1% increase compared to charcoal-based commercial AC(143.8 mg/g).
基金supported in part by the South Dakota Agricultural Experiment Station and the South Dakota 2010 Research Center,BCAAP(Biological Control and Analysis of Applied Photonics)Fund(3AH203 and 3SJ163 to FL)
文摘Dear Editor,Viruses are intracellular parasites that depend on cellular components to replicate.Viruses communicate withthe cellular machinery through protein–protein interactions(PPIs),for which each individual virus encodes aunique array of proteins.Each viral protein is capable ofindependently interacting with multiple cellular
基金supported by the grant from the"973"Program of China(No.2007CB411600)the Chinese Academy of Sciences(CAS)(No.kscx2-yw-z-1021)the"Xi Bu Zhi Guang"Program of CAS(No.XBBS201102)
文摘Although shifts in life-history traits of insular vertebrates, as compared with mainland populations, have been observed in many taxa, few studies have examined the relationships among individual life-history traits on islands. Lifehistory theory also predicts that there is a trade-off between body size and reproductive effort, and between egg size and clutch size. We surveyed the rice frog, Fejervarya limnocharis, on 20 islands within the Zhoushan Archipelago and two nearby sites on the mainland of China to compare differences in life-history traits and to explore relationships among those traits. Rice frog females reached a greater body size on half of the smaller islands among the total 20 surveyed islands, and larger egg size, decreased clutch size and reduced reproductive effort on most of the islands when compared to the two mainland sites. Insular body size was negatively correlated with reproductive effort. There was a negative correlation between egg size and clutch size. Results suggest that life-history theory provides a good explanation for co-variation between body size and reproductive effort, and between egg size and clutch size in rice frogs on the islands.
文摘The complex genetic architecture of quality traits has hindered efforts to modify seed nutrients in soybean. Genome-wide association studies were conducted for seed composition, including protein, oil, fatty acids, and amino acids, using 313 diverse soybean germplasm accessions genotyped with a high-density SNP array. A total of 87 chromosomal regions were identified to be associated with seed composition, explain- ing 8%-89% of genetic variances. The candidate genes GmSAT1, AK-HSDH, SACPD-C, and FAD3A of known function, and putative MtN21 nodulin, FATB, and steroid-5-^-reductase involved in N2 fixation, amino acid biosynthesis, and fatty acid metabolism were found at the major-effect loci. Further analysis of additional germplasm accessions indicated that these major-effect loci had been subjected to domes- tication or modern breeding selection, and the allelic variants and distributions were relevant to geographic regions. We also revealed that amino acid concentrations related to seed weight and to total protein had a different genetic basis. This helps uncover the in-depth genetic mechanism of the intricate relationships among the seed compounds. Thus, our study not only provides valuable genes and markers for soybean nutrient improvement, both quantitatively and qualitatively, but also offers insights into the alteration of soybean quality during domestication and breeding.
文摘Biotic and abiotic stress lead to elevated levels of jasmonic acid （JA） and its derivatives and activation of the biosynthesis of nicotine and related pyridine alkaloids in cultivated tobacco （Nicotiana tabacum L.）. Among the JA- responsive genes is NtPMTla, encoding putrescine N-methyl transferase, a key regulatory enzyme in nicotine formation. We have characterized three genes （NtMYC2a, b, c） encoding basic helix-loop-helix （bHLH） transcription factors （TFs） whose expression is rapidly induced by JA and that specifically activate JA-inducible NtPMTla expression by binding a G-box motif within the NtPMTla promoter in in vivo and in vitro assays. Using split-YFP assays, we further show that, in the absence of JA, NtMYC2a and NtMYC2b are present as nuclear complexes with the NtJAZ1 repressor. RNA interference （RNAi）-mediated knockdown of NtMYC2a and NtMYC2b expression results in significant decreases in JA-inducible NtPMTla transcript levels, as well as reduced levels of transcripts encoding other enzymes involved in nicotine and minor alkaloid biosynthesis, in- cluding an 80-90% reduction in the level of transcripts encoding the putative nicotine synthase gene NtA662. In contrast, ectopic overexpression of NtMYC2a and NtMYC2b had no effect on NtPMTla expression in the presence or absence of exogenously added JA. These data suggest that NtMYC2a, b, c are required components of JA-inducible expression of multiple genes in the nicotine biosynthetic pathway and may act additively in the activation of JA responses.
基金supported by Public Health Service grants(AI071788 and AI076125)to Feng Li
文摘Despite significant advances in antiretroviral therapy,increasing drug resistance and toxicities observed among many of the current approved human immunodeficiency virus(HIV) drugs indicate a need for discovery and development of potent and safe antivirals with a novel mechanism of action.Maturation inhibitors(MIs) represent one such new class of HIV therapies.MIs inhibit a late step in the HIV-1 Gag processing cascade,causing defective core condensation and the release of non-infectious virus particles from infected cells,thus blocking the spread of the infection to new cells.Clinical proof-ofconcept for the MIs was established with betulinic acid derived bevirimat,the prototype HIV-1 MI.Despite the discontinuation of its further clinical development in 2010 due to a lack of uniform patient response caused by naturally occurring drug resistance Gag polymorphisms,several second-generation MIs with improved activity against viruses exhibiting Gag polymorphism mediated resistance have been recently discovered and are under clinical evaluation in HIV/AID patients.In this review,current understanding of HIV-1 MIs is described and recent progress made toward elucidating the mechanism of action,target identification and development of second-generation MIs is reviewed.
基金funded by the National Basic Research Program(973 Program) of China(No. 2009CB118300)the National Natural Science Foundation of China(No.31071420)+1 种基金Doctoral Fund(No.2.00951E+13)the 100-Talent Program of CAS,the Education Commission and Science and Technology Commission of Sichuan Province and by South Dakota Agricultural Experiment Station
文摘Doubled haploid （DH） populations are useful to scientists and breeders in both crop improvement and basic research. Current methods of producing DHs usually need in vitro culture for extracting haploids and chemical treatment for chromosome doubling. This report describes a simple method for synthesizing DHs （SynDH） especially for allopolyploid species by utilizing meiotic restitution genes. The method involves three steps： hybridization to induce recombination, interspecific hybridization to extract haploids, and spontaneous chromosome doubling by selfing the interspecific Fis. DHs produced in this way contain recombinant chromosomes in the genome（s） of interest in a homogeneous background. No special equipment or treatments are involved in the DH production and it can be easily applied in any breeding and/or genetic program. Triticum turgidum L. and Aegilops tauschii Coss, the two ancestral species of common wheat （Triticurn aestivum L.） and molecular markers were used to demonstrate the SynDH method.
