ABSTRACT
We searched for genetic linkage between DNA markers and quantitative trait loci (QTLs) for innate immunity, response to stress, biochemical parameters of blood, and fish size in an F2 population derived from an interspecific tilapia hybrid (Oreochromis mossambicusx O. aureus). A family of 114 fish was scanned for 40 polymorphic microsatellite DNA markers and two polymorphic genes, covering approximately 80% of the tilapia genome. These fish had previously been phenotyped for seven immune-response traits and six blood parameters. Critical values for significance were P <0.05 with the false discovery rate (FDR) controlled at 40%. The genome-scan analysis resulted in 35 significant marker-trait associations, involving 26 markers in 16 linkage groups. In a second experiment, nine markers were re-sampled in a second family of 79 fish of the same species hybrid. Seven markers (GM180, GM553, MHC-I, UNH848, UNH868, UNH898 and UNH925) in five linkage groups (LG 1, 3, 4, 22 and 23) were associated with stress response traits. An additional six markers (GM47, GM552, UNH208, UNH881, UNH952, UNH998) in five linkage groups (LG 4, 16, 19, 20 and 23) were verified for their associations with immune response traits, by linkage to several different traits. The portion of variance explained by each QTL was 11% on average, with a maximum of 29%. The average additive effect of QTLs was 0.2 standard deviation units of stress response traits and fish size, with a maximum of 0.33. In three linkage groups (LG 1, 3 and 23) markers were associated with stress response, body weight and sex determination, confirming the location of QTLs reported by several other studies.
Subject(s)
Quantitative Trait Loci , Tilapia/genetics , Animals , Chromosome Mapping , DNA/genetics , Female , Genetic Markers , Genome , Hybridization, Genetic , Male , Microsatellite Repeats , Phenotype , Stress, Physiological/geneticsABSTRACT
Mice infected with Brucella melitensis were treated with azithromycin or roxithromycin at a dose of 50 mg/kg/day i.p. alone and in combination with streptomycin 75 mg/kg/day for 14 days. Streptomycin at this dose was previously documented to be ineffective against murine brucellosis. Azithromycin- and azithromycin/streptomycin-treated animals demonstrated a significantly better cure rate than controls. Therapy failure was observed in all mice treated with roxithromycin 50 mg/kg/day i.p. alone or in combination with streptomycin 75 mg/kg/day. Our findings demonstrate that azithromycin cures experimental murine brucellosis and may be an effective alternative in the therapy of human brucellosis.
