An improved method of PCR in which the small segment of conchocelis is amplified directly without DNA extraction was used to amplify a RUBISCO intergenic spacer DNA fragment from nine species of red algal genus Porphy...An improved method of PCR in which the small segment of conchocelis is amplified directly without DNA extraction was used to amplify a RUBISCO intergenic spacer DNA fragment from nine species of red algal genus Porphyra(Bangiales,Rhodophyta),including Porphyra yezoensis(Jiangsu,China),P.haitanensis(Fujian,China),P.oligospermatangia(Qingdao,China),P.katadai(Qingdao,China),P.tenera(Qingdao,China),P.suborboculata(Fujian,China),P.pseudolinearis(Kogendo,Korea),P.linearis(Devon,England),and P.fallax(Seattle,USA).Standard PCR and the method developed here were both conducted using primers specific for the RUBISCO spacer region,after which the two PCR products were sequenced.The sequencing data of the amplicons obtained using both methods were identical,suggesting that the improved PCR method was functional.These findings indicate that the method developed here may be useful for the rapid identification of species of Porphyra in a germplasm bank.In addition,a phylogenetic tree was constructed using the RUBISCO spacer and partial rbcS sequence,and the results were in concordant with possible alternative phylogenies based on traditional morphological taxonomic characteristics,indicating that the RUBISCO spacer is a useful region for phylogenetic studies.展开更多
The aim of this research was to examine the influence of vanadium on the structure, hardness and tensile strength of X I60CrMo 12-1 self-hardened steels. It is known that vanadium affects the process of solidification...The aim of this research was to examine the influence of vanadium on the structure, hardness and tensile strength of X I60CrMo 12-1 self-hardened steels. It is known that vanadium affects the process of solidification of this alloy in a way that narrows temperature interval of crystallization. Vanadium, as an alloying element, moves liquidus and solidus lines toward higher temperatures, approximately for 25 to 30 ~C. In addition, vanadium forms V6C5 carbides, which, are partly distributed between present phases in the steel; carbide （Cr,Fe）7C3 and austenite. The presence of vanadium enables the formation of （Cr, Fe）23C6 carbide and its precipitation into austenite during the cooling process. In local areas around fine carbide particles, austenite is transformed into martensite, i.e., vanadium reduces remained austenite and improves steel air-hardening. Vanadium concentration over 2.5% significantly improves the impact toughness. The basic problem in the application of high alloyed Cr-Mo steels is to increase their impact toughness and thereby sustain a relatively high value of hardness. Recent studies, concerning to the chemical composition and heat treatment regime, show that it is possible to get a martensitic structure with a very small amount of retained austenite. Investigations are directed toward the testing of the influence of alloying elements such as molybdenum, manganese and especially vanadium. Vanadium has great influence to the crystallization process. With increasing of its content, the eutectic point moves toward lower carbon concentrations and the temperature interval of solidification is narrowing.展开更多
Restriction fragment length polymorphism （RFLP） profiles of the amplified products of Internal Transcribed Spacer （ITS） region of rDNA using four restriction enzymes （Alul, Rsal, HinfI and HhaI） revealed distinc...Restriction fragment length polymorphism （RFLP） profiles of the amplified products of Internal Transcribed Spacer （ITS） region of rDNA using four restriction enzymes （Alul, Rsal, HinfI and HhaI） revealed distinctness of six Indian isolates of Steinernema one each from Maharashtra （IARI-EPN-mh）, Himachal Pradesh （IARI-EPN-hp）, Dehradun （IARI-EPN-dhdl）, Jharkhand （IARI-EPN-jhl） and two from Madhya Pradesh （IARI-EPN-bpll ＆ IARI-EPN-gwll）, when compared with the only native species Steinernema thermophilum. One of the restriction enzyme, Rsal could differentiate all the six species/strains from one another. The three restriction enzymes yielded patterns which were of diagnostic value but Rsal appeared to be the best diagnostic marker for differentiating these isolates. A tree constructed based upon the band sharing amongst the isolates, produced trichotomy which placed strains from Madhya Pradesh and Jharkhand in one group showing 94% homology, one strain from Bhopal （M.P） formed separate clade along with S. thermophilum with 72% similarity. These isolates, from Maharashtra, Himachal Pradesh and Dehradun, showed only 51% similarity with the S. thermophilum by forming separate clade.展开更多
基金Supported by the National High Technology Research and Development Program of China (863 Program)(No 2006AA10A402)Project for Supporting National Development (No 2006BAD09A04)+2 种基金the National Natural Science Foundation of China (Nos U0633006,40476059)the Natural Science Foundation of Qingdao (No 05-2-p-2)the Knowledge Innovation Program of the Chinese Academy of Sciences (No KZCX2-211)
文摘An improved method of PCR in which the small segment of conchocelis is amplified directly without DNA extraction was used to amplify a RUBISCO intergenic spacer DNA fragment from nine species of red algal genus Porphyra(Bangiales,Rhodophyta),including Porphyra yezoensis(Jiangsu,China),P.haitanensis(Fujian,China),P.oligospermatangia(Qingdao,China),P.katadai(Qingdao,China),P.tenera(Qingdao,China),P.suborboculata(Fujian,China),P.pseudolinearis(Kogendo,Korea),P.linearis(Devon,England),and P.fallax(Seattle,USA).Standard PCR and the method developed here were both conducted using primers specific for the RUBISCO spacer region,after which the two PCR products were sequenced.The sequencing data of the amplicons obtained using both methods were identical,suggesting that the improved PCR method was functional.These findings indicate that the method developed here may be useful for the rapid identification of species of Porphyra in a germplasm bank.In addition,a phylogenetic tree was constructed using the RUBISCO spacer and partial rbcS sequence,and the results were in concordant with possible alternative phylogenies based on traditional morphological taxonomic characteristics,indicating that the RUBISCO spacer is a useful region for phylogenetic studies.
文摘The aim of this research was to examine the influence of vanadium on the structure, hardness and tensile strength of X I60CrMo 12-1 self-hardened steels. It is known that vanadium affects the process of solidification of this alloy in a way that narrows temperature interval of crystallization. Vanadium, as an alloying element, moves liquidus and solidus lines toward higher temperatures, approximately for 25 to 30 ~C. In addition, vanadium forms V6C5 carbides, which, are partly distributed between present phases in the steel; carbide （Cr,Fe）7C3 and austenite. The presence of vanadium enables the formation of （Cr, Fe）23C6 carbide and its precipitation into austenite during the cooling process. In local areas around fine carbide particles, austenite is transformed into martensite, i.e., vanadium reduces remained austenite and improves steel air-hardening. Vanadium concentration over 2.5% significantly improves the impact toughness. The basic problem in the application of high alloyed Cr-Mo steels is to increase their impact toughness and thereby sustain a relatively high value of hardness. Recent studies, concerning to the chemical composition and heat treatment regime, show that it is possible to get a martensitic structure with a very small amount of retained austenite. Investigations are directed toward the testing of the influence of alloying elements such as molybdenum, manganese and especially vanadium. Vanadium has great influence to the crystallization process. With increasing of its content, the eutectic point moves toward lower carbon concentrations and the temperature interval of solidification is narrowing.
文摘Restriction fragment length polymorphism （RFLP） profiles of the amplified products of Internal Transcribed Spacer （ITS） region of rDNA using four restriction enzymes （Alul, Rsal, HinfI and HhaI） revealed distinctness of six Indian isolates of Steinernema one each from Maharashtra （IARI-EPN-mh）, Himachal Pradesh （IARI-EPN-hp）, Dehradun （IARI-EPN-dhdl）, Jharkhand （IARI-EPN-jhl） and two from Madhya Pradesh （IARI-EPN-bpll ＆ IARI-EPN-gwll）, when compared with the only native species Steinernema thermophilum. One of the restriction enzyme, Rsal could differentiate all the six species/strains from one another. The three restriction enzymes yielded patterns which were of diagnostic value but Rsal appeared to be the best diagnostic marker for differentiating these isolates. A tree constructed based upon the band sharing amongst the isolates, produced trichotomy which placed strains from Madhya Pradesh and Jharkhand in one group showing 94% homology, one strain from Bhopal （M.P） formed separate clade along with S. thermophilum with 72% similarity. These isolates, from Maharashtra, Himachal Pradesh and Dehradun, showed only 51% similarity with the S. thermophilum by forming separate clade.
