The genome sequence of the Severe Acute Respiratory Syndrome (SARS)-associated virus provides essential information for the identification of pathogen(s), exploration of etiology and evolution, interpretation of trans...The genome sequence of the Severe Acute Respiratory Syndrome (SARS)-associated virus provides essential information for the identification of pathogen(s), exploration of etiology and evolution, interpretation of transmission and pathogenesis, development of diagnostics, prevention by future vaccination, and treatment by developing new drugs. We report the complete genome sequence and comparative analysis of an isolate (BJ01) of the coronavirus that has been recognized as a pathogen for SARS. The genome is 29725 nt in size and has 11 ORFs (Open Reading Frames). It is composed of a stable region encoding an RNA-dependent RNA polymerase (composed of 2 ORFs) and a variable region representing 4 CDSs (coding sequences) for viral structural genes (the S, E, M, N proteins) and 5 PUPs (putative uncharacterized proteins). Its gene order is identical to that of other known coronaviruses. The sequence alignment with all known RNA viruses places this virus as a member in the family of Coronaviridae. Thirty putative substitutions have been identified by comparative analysis of the 5 SARS- associated virus genome sequences in GenBank. Fifteen of them lead to possible amino acid changes (non-synonymous mutations) in the proteins. Three amino acid changes, with predicted alteration of physical and chemical features, have been detected in the S protein that is postulated to beinvolved in the immunoreactions between the virus and its host. Two amino acid changes have been detected in the Mprotein, which could be related to viral envelope formation. Phylogenetic analysis suggests the possibility of non-human origin of the SARS-associated viruses but provides noevidence that they are man-made. Further efforts should focus on identifying the etiology of the SARS-associated virus and ruling out conclusively the existence of otherpossible SARS-related pathogen(s).展开更多
Molecular systematics has developed very quickly these years,on which most studies of molecular ecology have been focused.In this paper,the main content of this comprehensive subject is briefly reviewed.We emphasized ...Molecular systematics has developed very quickly these years,on which most studies of molecular ecology have been focused.In this paper,the main content of this comprehensive subject is briefly reviewed.We emphasized on its techniques,including their principles,advantages and disadvantages as their applications.Several problems have been enumerated which exist in recent research of molecular systematics.The development tendency of molecular systematics is also discussed in this paper.展开更多
ITS sequences of 15 representative species of five sections in the genus Populus L. were determined. By using direct sequencing of PCR product, it was found that the fragments of internal transcribed spacers （ITS） a...ITS sequences of 15 representative species of five sections in the genus Populus L. were determined. By using direct sequencing of PCR product, it was found that the fragments of internal transcribed spacers （ITS） are about 594 bp in length. The length of ITS1 and ITS2 is about 220 bp and 210 bp, respectively, while that of 5.8s is 164 bp. Its G+C content is about 69.0%. The number of phylogenetically informative loci is higher in ITS2 than in ITS1. Transversion and transition are two main factors that drive the ITS evolution, and more insertions and deletions occurred in ITS2. Taking Salix matsudana Koidz. and Salix suchowensis Cheng as outgroups, phylogenetic analysis of ITS sequences using PAUP 4.0 software indicated that Populus is monophyletic group and can be divided into two main clades. One is the section Leuce , and the other is the remaining sections.展开更多
文摘The genome sequence of the Severe Acute Respiratory Syndrome (SARS)-associated virus provides essential information for the identification of pathogen(s), exploration of etiology and evolution, interpretation of transmission and pathogenesis, development of diagnostics, prevention by future vaccination, and treatment by developing new drugs. We report the complete genome sequence and comparative analysis of an isolate (BJ01) of the coronavirus that has been recognized as a pathogen for SARS. The genome is 29725 nt in size and has 11 ORFs (Open Reading Frames). It is composed of a stable region encoding an RNA-dependent RNA polymerase (composed of 2 ORFs) and a variable region representing 4 CDSs (coding sequences) for viral structural genes (the S, E, M, N proteins) and 5 PUPs (putative uncharacterized proteins). Its gene order is identical to that of other known coronaviruses. The sequence alignment with all known RNA viruses places this virus as a member in the family of Coronaviridae. Thirty putative substitutions have been identified by comparative analysis of the 5 SARS- associated virus genome sequences in GenBank. Fifteen of them lead to possible amino acid changes (non-synonymous mutations) in the proteins. Three amino acid changes, with predicted alteration of physical and chemical features, have been detected in the S protein that is postulated to beinvolved in the immunoreactions between the virus and its host. Two amino acid changes have been detected in the Mprotein, which could be related to viral envelope formation. Phylogenetic analysis suggests the possibility of non-human origin of the SARS-associated viruses but provides noevidence that they are man-made. Further efforts should focus on identifying the etiology of the SARS-associated virus and ruling out conclusively the existence of otherpossible SARS-related pathogen(s).
文摘Molecular systematics has developed very quickly these years,on which most studies of molecular ecology have been focused.In this paper,the main content of this comprehensive subject is briefly reviewed.We emphasized on its techniques,including their principles,advantages and disadvantages as their applications.Several problems have been enumerated which exist in recent research of molecular systematics.The development tendency of molecular systematics is also discussed in this paper.
文摘ITS sequences of 15 representative species of five sections in the genus Populus L. were determined. By using direct sequencing of PCR product, it was found that the fragments of internal transcribed spacers （ITS） are about 594 bp in length. The length of ITS1 and ITS2 is about 220 bp and 210 bp, respectively, while that of 5.8s is 164 bp. Its G+C content is about 69.0%. The number of phylogenetically informative loci is higher in ITS2 than in ITS1. Transversion and transition are two main factors that drive the ITS evolution, and more insertions and deletions occurred in ITS2. Taking Salix matsudana Koidz. and Salix suchowensis Cheng as outgroups, phylogenetic analysis of ITS sequences using PAUP 4.0 software indicated that Populus is monophyletic group and can be divided into two main clades. One is the section Leuce , and the other is the remaining sections.
