A repetitive element (IS986), previously isolated from Mycobacterium tuberculosis and shown to de... more A repetitive element (IS986), previously isolated from Mycobacterium tuberculosis and shown to detect multiple restriction fragment-length polymorphisms (RFLPs), has been sequenced. It consists of a potential insertion sequence of 1358bp, with 30-bp inverted repeat ends. IS986 has four potentially significant open reading frames (ORFs): ORFa1, ORFa2 and ORFb on one strand and ORFc on the complementary strand. The sequences of the potential translated products identify IS986 as a member of the IS3 family, with an apparent frameshift between ORFa1 and ORFa2. IS986 has potential as a highly specific probe for detection and typing of M. tuberculosis, as well as for transposon mutagenesis of mycobacteria. The sequence of IS986 is virtually identical to that of another recently described element, IS6110 (Thierry et al., 1990).
One limiting factor in studies of tuberculosis and leprosy is the difficulty of genetic analysis ... more One limiting factor in studies of tuberculosis and leprosy is the difficulty of genetic analysis and manipulation of mycobacteria. Two approaches were adopted for the construction of vectors, based on different Escherichia coli plasmids and using Mycobacterium smegmatis as the host. In both cases we found that the original E. coli plasmid is capable of being replicated in M. smegmatis, yielding chloramphenicol-resistant colonies. One such plasmid has been recovered from a M. smegmatis transformant and used to re-transform both M. smegmatis and E. coli to chloramphenicol resistance. This plasmid is indistinguishable from the original plasmid by restriction analysis, and can be used as a shuttle vector for the genetic manipulation of mycobacterial species.
Clinical isolates of Mycobacterium tuberculosis were shown by Southern blotting to contain DNA se... more Clinical isolates of Mycobacterium tuberculosis were shown by Southern blotting to contain DNA sequences hybridizing to a probe derived from a Mycobacterium fortuitum plasmid. Two such M. tuberculosis DNA fragments, isolated from a gene library, were used as probes to show restriction fragment length polymorphism in M. tuberculosis strains by detecting a repetitive sequence apparently located at different points on the chromosome. This could indicate the presence of a transposable element in M. tuberculosis which is partly homologous to a region of the M. fortuitum plasmid. The probes described can be used to fingerprint M. tuberculosis isolates, and in addition are capable of distinguishing M. tuberculosis from Mycobacterium bovis and BCG.
Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO m... more Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO molecules upon irradiation in deoxygenated aqueous solution. Hydrogen atoms are less reactive. The rate constant of the reaction of hydrated electrons with PEO is lower than 5 × 106 dm3 mol−1 s−1. For dilute PEO solutions the relationship between the rate constant of .OH reaction with PEO and the chain length, based on Smoluchowski equation, is valid over a broad range of molecular weight.
Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO m... more Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO molecules upon irradiation in deoxygenated aqueous solution. Hydrogen atoms are less reactive. The rate constant of the reaction of hydrated electrons with PEO is lower than 5 × 106 dm3 mol−1 s−1. For dilute PEO solutions the relationship between the rate constant of .OH reaction with PEO and the chain length, based on Smoluchowski equation, is valid over a broad range of molecular weight.
A repetitive element (IS986), previously isolated from Mycobacterium tuberculosis and shown to de... more A repetitive element (IS986), previously isolated from Mycobacterium tuberculosis and shown to detect multiple restriction fragment-length polymorphisms (RFLPs), has been sequenced. It consists of a potential insertion sequence of 1358bp, with 30-bp inverted repeat ends. IS986 has four potentially significant open reading frames (ORFs): ORFa1, ORFa2 and ORFb on one strand and ORFc on the complementary strand. The sequences of the potential translated products identify IS986 as a member of the IS3 family, with an apparent frameshift between ORFa1 and ORFa2. IS986 has potential as a highly specific probe for detection and typing of M. tuberculosis, as well as for transposon mutagenesis of mycobacteria. The sequence of IS986 is virtually identical to that of another recently described element, IS6110 (Thierry et al., 1990).
One limiting factor in studies of tuberculosis and leprosy is the difficulty of genetic analysis ... more One limiting factor in studies of tuberculosis and leprosy is the difficulty of genetic analysis and manipulation of mycobacteria. Two approaches were adopted for the construction of vectors, based on different Escherichia coli plasmids and using Mycobacterium smegmatis as the host. In both cases we found that the original E. coli plasmid is capable of being replicated in M. smegmatis, yielding chloramphenicol-resistant colonies. One such plasmid has been recovered from a M. smegmatis transformant and used to re-transform both M. smegmatis and E. coli to chloramphenicol resistance. This plasmid is indistinguishable from the original plasmid by restriction analysis, and can be used as a shuttle vector for the genetic manipulation of mycobacterial species.
Clinical isolates of Mycobacterium tuberculosis were shown by Southern blotting to contain DNA se... more Clinical isolates of Mycobacterium tuberculosis were shown by Southern blotting to contain DNA sequences hybridizing to a probe derived from a Mycobacterium fortuitum plasmid. Two such M. tuberculosis DNA fragments, isolated from a gene library, were used as probes to show restriction fragment length polymorphism in M. tuberculosis strains by detecting a repetitive sequence apparently located at different points on the chromosome. This could indicate the presence of a transposable element in M. tuberculosis which is partly homologous to a region of the M. fortuitum plasmid. The probes described can be used to fingerprint M. tuberculosis isolates, and in addition are capable of distinguishing M. tuberculosis from Mycobacterium bovis and BCG.
Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO m... more Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO molecules upon irradiation in deoxygenated aqueous solution. Hydrogen atoms are less reactive. The rate constant of the reaction of hydrated electrons with PEO is lower than 5 × 106 dm3 mol−1 s−1. For dilute PEO solutions the relationship between the rate constant of .OH reaction with PEO and the chain length, based on Smoluchowski equation, is valid over a broad range of molecular weight.
Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO m... more Hydroxyl radicals are the main precursors of macroradicals formed at poly(ethylene oxide) - PEO molecules upon irradiation in deoxygenated aqueous solution. Hydrogen atoms are less reactive. The rate constant of the reaction of hydrated electrons with PEO is lower than 5 × 106 dm3 mol−1 s−1. For dilute PEO solutions the relationship between the rate constant of .OH reaction with PEO and the chain length, based on Smoluchowski equation, is valid over a broad range of molecular weight.
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