scholarly journals Analysis of the promoter region of the cloned kanamycin resistance gene (kmr) from Streptomyces kanamyceticus.

1989 ◽  
Vol 42 (3) ◽  
pp. 413-422 ◽  
Author(s):  
MICHIKO M. NAKANO ◽  
TAKAO KIKUCHI ◽  
HIROSHI MASHIKO ◽  
HIROSHI OGAWARA
2001 ◽  
Vol 69 (4) ◽  
pp. 2137-2143 ◽  
Author(s):  
Karen B. Register ◽  
Thomas F. Ducey ◽  
Susan L. Brockmeier ◽  
David W. Dyer

ABSTRACT One means by which Bordetella bronchiseptica scavenges iron is through production of the siderophore alcaligin. A nonrevertible alcaligin mutant derived from the virulent strain 4609, designated DBB25, was constructed by insertion of a kanamycin resistance gene into alcA, one of the genes essential for alcaligin biosynthesis. The virulence of the alcA mutant in colostrum-deprived, caesarean-delivered piglets was compared with that of the parent strain in two experiments. At 1 week of age, piglets were inoculated with phosphate-buffered saline, 4609, or DBB25. Two piglets in each group were euthanatized on day 10 postinfection. The remainder were euthanatized at 21 days postinfection. Clinical signs, including fever, coughing, and sneezing, were present in both groups. Nasal washes performed 7, 14, and 21 days postinoculation demonstrated that strain DBB25 colonized the nasal cavity but did so at levels that were significantly less than those achieved by strain 4609. Analysis of colonization based on the number of CFU per gram of tissue recovered from the turbinate, trachea, and lung also demonstrated significant differences between DBB25 and 4609, at both day 10 and day 21 postinfection. Mild to moderate turbinate atrophy was apparent in pigs inoculated with strain 4609, while turbinates of those infected with strain DBB25 developed no or mild atrophy. We conclude from these results that siderophore production by B. bronchiseptica is not essential for colonization of swine but is required for maximal virulence. B. bronchiseptica mutants with nonrevertible defects in genes required for alcaligin synthesis may be candidates for evaluation as attenuated, live vaccine strains in conventionally reared pigs.


2020 ◽  
Vol 42 (11) ◽  
pp. 2223-2230
Author(s):  
Rafael A. Donassolo ◽  
Marcos Roberto A. Ferreira ◽  
Clóvis Moreira Jr ◽  
Lucas M. dos Santos ◽  
Emili Griep ◽  
...  

2000 ◽  
Vol 182 (8) ◽  
pp. 2269-2276 ◽  
Author(s):  
Zhenying Liu ◽  
Nicolas Guiliani ◽  
Corinne Appia-Ayme ◽  
Françoise Borne ◽  
Jeanine Ratouchniak ◽  
...  

ABSTRACT To construct Thiobacillus ferrooxidans mutants by marker exchange mutagenesis, a genetic transfer system is required. The transfer of broad-host-range plasmids belonging to the incompatibility groups IncQ (pKT240 and pJRD215), IncP (pJB3Km1), and IncW (pUFR034) from Escherichia coli to two private T. ferrooxidans strains (BRGM1 and Tf-49) and to two collection strains (ATCC 33020 and ATCC 19859) by conjugation was analyzed. To knock out the T. ferrooxidans recA gene, a mobilizable suicide plasmid carrying the ATCC 33020 recA gene disrupted by a kanamycin resistance gene was transferred from E. colito T. ferrooxidans ATCC 33020 by conjugation under the best conditions determined. The two kanamycin-resistant clones, which have retained the kanamycin-resistant phenotype after growth for several generations in nonselective medium, were shown to have the kanamycin resistance gene inserted within the recA gene, indicating that the recA::Ω-Km mutated allele was transferred from the suicide plasmid to the chromosome by homologous recombination. These mutants exhibited a slightly reduced growth rate and an increased sensitivity to UV and γ irradiation compared to the wild-type strain. However, the T. ferrooxidans recA mutants are less sensitive to these physical DNA-damaging agents than therecA mutants described in other bacterial species, suggesting that RecA plays a minor role in DNA repair in T. ferrooxidans.


2004 ◽  
Vol 186 (22) ◽  
pp. 7804-7806 ◽  
Author(s):  
Renata Moreno ◽  
Aurelio Hidalgo ◽  
Felipe Cava ◽  
Roberto Fernández-Lafuente ◽  
José Manuel Guisán ◽  
...  

ABSTRACT The expression of an antisense RNA revealed that an Mn-catalase was required in Thermus thermophilus for aerobic but not for anaerobic growth. The antisense system is based on the constitutive expression of a “bicistronic” transcript consisting of the kanamycin resistance gene mRNA followed by the antisense RNA against the selected target.


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