It is now well established that in vertebrate striated muscle there are two kinds of filaments, the thick filament and the thin filament. The evidence is strong that myosin is located in the former and actin in the la...It is now well established that in vertebrate striated muscle there are two kinds of filaments, the thick filament and the thin filament. The evidence is strong that myosin is located in the former and actin in the latter. By a direct isolation procedure we could also find tropomyosin in the thin filament. In the smooth molluscan adductor muscle, structural evidence has also been obtained for the presence of two kinds of filaments, but here the thick one is replaced by the very much thicker filament with characteristic 145 A cross-striations. The formal resemblance between the band patterns of this muscle and those of the crystal of para-展开更多
南极海豹是南极及南大洋的主要哺乳动物之一,它们在南极及南大洋生态系中占有重要地位,也是南极的主要生物资源之一。 关于南极海豹的数量分布、种群动态、生态习性以及它们之间的相互作用已有不少报导(陈万青,1973;宁修仁,1984;Bengtso...南极海豹是南极及南大洋的主要哺乳动物之一,它们在南极及南大洋生态系中占有重要地位,也是南极的主要生物资源之一。 关于南极海豹的数量分布、种群动态、生态习性以及它们之间的相互作用已有不少报导(陈万青,1973;宁修仁,1984;Bengtson, J. L.,Carrick, R.,1962;Erckson,A. W. , 1970,1971;和Davis, R. M. ,1970等)。现有的研究结果表明,在南极繁殖的真正海豹有四种,即锯齿海豹,又名食蟹海豹,其英文名为Crabeater Seal(Lobodon Carcino phagus),这是南极海豹中数量最多的一种,据估计有200—500万头,它们主要以南极磷虾而不是以蟹为食;威德尔海豹,其英文名为Weddell Seal(leptonychotes weddelli),这种海豹的数量占南极海豹第二位,估计有20—50万头;它们主要以乌贼和杜文鱼及磷虾为食;豹形海豹,其英文名为Leopard Seal(Hydrurga leptonyx);罗斯海豹,其英文名为Ross Seal(Ommatophoca ross Gray)。展开更多
Ⅰ. INTRODUCTION Proteinases and their inhibitors are widely distributed in nature. They play important roles in the biological regulation and control of a number of physiological processes. More than one hundred inhi...Ⅰ. INTRODUCTION Proteinases and their inhibitors are widely distributed in nature. They play important roles in the biological regulation and control of a number of physiological processes. More than one hundred inhibitors from different sources have been isolated and some of them investigated biochemically in detail. Among them,展开更多
Geminivirus is a group of new plant virus, the single-strandedness of the smallest DNA genome and geminate morphology of which are different from those of all other groups of viruses described so far. Since the discov...Geminivirus is a group of new plant virus, the single-strandedness of the smallest DNA genome and geminate morphology of which are different from those of all other groups of viruses described so far. Since the discovery of geminivirus in the beet curly top disease and the maize streak disease less than ten years ago, over ten展开更多
Wheat rosette stunt virus (WRSV) contains an RNA-dependent RNA polymerase. The RNA polymerase activity is associated with the viral nucleocapsid (NP).In vitro transcription of purified NP required all of the four nucl...Wheat rosette stunt virus (WRSV) contains an RNA-dependent RNA polymerase. The RNA polymerase activity is associated with the viral nucleocapsid (NP).In vitro transcription of purified NP required all of the four nucleoside triphosphates and Mg^(2+).There was a need of a proper salt concentration and some reducing reagents in the system for increasing the RNA polymerase activity.The optimum temperature for in vitro transcription was around 25℃.Within the first 90 min of in vitro reaction, incorporation rose linearly with the time course of incubation. The experiments of ribonuclease and deoxyribonuclease treatments showed that single-stranded RNAs were synthesized in vitro by the RNA polymerase.Two fractions of WRSV-NP could be separated by SDS-dissociation and ultracentrifugation.The supernatant fraction contained three structural proteins of NP: L, N and NS;and the pellet fraction contained the viral RNA.When the supernatant proteins and the viral RNA were mixed together, RNA polymerase activity could be reconstituted.When the ratio between the amounts of the supernatant proteins and the viral RNA in the mixture was about 100:7.7, the reconstituted RNA polymerase activity reached the maximum.展开更多
The Mung bean trypsin inhibitor belongs to the Bowman-Birk inhibitor family. It consists of 72 amino acid residues with 7 pairs of disulfide bonds, and its amino acid sequence has been elucidated. The inhibitor compri...The Mung bean trypsin inhibitor belongs to the Bowman-Birk inhibitor family. It consists of 72 amino acid residues with 7 pairs of disulfide bonds, and its amino acid sequence has been elucidated. The inhibitor comprises two reactive sites identified as Lys-Ser and Arg-Ser respectively. Consequently, the inhibitor is capable of combining trypsin at a molar ratio展开更多
文摘It is now well established that in vertebrate striated muscle there are two kinds of filaments, the thick filament and the thin filament. The evidence is strong that myosin is located in the former and actin in the latter. By a direct isolation procedure we could also find tropomyosin in the thin filament. In the smooth molluscan adductor muscle, structural evidence has also been obtained for the presence of two kinds of filaments, but here the thick one is replaced by the very much thicker filament with characteristic 145 A cross-striations. The formal resemblance between the band patterns of this muscle and those of the crystal of para-
文摘南极海豹是南极及南大洋的主要哺乳动物之一,它们在南极及南大洋生态系中占有重要地位,也是南极的主要生物资源之一。 关于南极海豹的数量分布、种群动态、生态习性以及它们之间的相互作用已有不少报导(陈万青,1973;宁修仁,1984;Bengtson, J. L.,Carrick, R.,1962;Erckson,A. W. , 1970,1971;和Davis, R. M. ,1970等)。现有的研究结果表明,在南极繁殖的真正海豹有四种,即锯齿海豹,又名食蟹海豹,其英文名为Crabeater Seal(Lobodon Carcino phagus),这是南极海豹中数量最多的一种,据估计有200—500万头,它们主要以南极磷虾而不是以蟹为食;威德尔海豹,其英文名为Weddell Seal(leptonychotes weddelli),这种海豹的数量占南极海豹第二位,估计有20—50万头;它们主要以乌贼和杜文鱼及磷虾为食;豹形海豹,其英文名为Leopard Seal(Hydrurga leptonyx);罗斯海豹,其英文名为Ross Seal(Ommatophoca ross Gray)。
文摘Ⅰ. INTRODUCTION Proteinases and their inhibitors are widely distributed in nature. They play important roles in the biological regulation and control of a number of physiological processes. More than one hundred inhibitors from different sources have been isolated and some of them investigated biochemically in detail. Among them,
文摘Geminivirus is a group of new plant virus, the single-strandedness of the smallest DNA genome and geminate morphology of which are different from those of all other groups of viruses described so far. Since the discovery of geminivirus in the beet curly top disease and the maize streak disease less than ten years ago, over ten
基金Project supported by the National Natural Science Foundation of China.
文摘Wheat rosette stunt virus (WRSV) contains an RNA-dependent RNA polymerase. The RNA polymerase activity is associated with the viral nucleocapsid (NP).In vitro transcription of purified NP required all of the four nucleoside triphosphates and Mg^(2+).There was a need of a proper salt concentration and some reducing reagents in the system for increasing the RNA polymerase activity.The optimum temperature for in vitro transcription was around 25℃.Within the first 90 min of in vitro reaction, incorporation rose linearly with the time course of incubation. The experiments of ribonuclease and deoxyribonuclease treatments showed that single-stranded RNAs were synthesized in vitro by the RNA polymerase.Two fractions of WRSV-NP could be separated by SDS-dissociation and ultracentrifugation.The supernatant fraction contained three structural proteins of NP: L, N and NS;and the pellet fraction contained the viral RNA.When the supernatant proteins and the viral RNA were mixed together, RNA polymerase activity could be reconstituted.When the ratio between the amounts of the supernatant proteins and the viral RNA in the mixture was about 100:7.7, the reconstituted RNA polymerase activity reached the maximum.
文摘The Mung bean trypsin inhibitor belongs to the Bowman-Birk inhibitor family. It consists of 72 amino acid residues with 7 pairs of disulfide bonds, and its amino acid sequence has been elucidated. The inhibitor comprises two reactive sites identified as Lys-Ser and Arg-Ser respectively. Consequently, the inhibitor is capable of combining trypsin at a molar ratio
