ABSTRACT
Body size is an archetypal quantitative trait with variation due to the segregation of many gene loci, each of relatively minor effect, and the environment. We examine the effects of quantitative trait loci (QTLs) on age-specific body weights and growth in the F2 intercross of the LG/J and SM/J strains of inbred mice. Weekly weights (1-10 wk) and 75 microsatellite genotypes were obtained for 535 mice. Interval mapping was used to locate and measure the genotypic effects of QTLs on body weight and growth. QTL effects were detected on 16 of the 19 autosomes with several chromosomes carrying more than one QTL. The number of QTLs for age-specific weights varied from seven at 1 week to 17 at 10 wk. The QTLs were each of relatively minor, subequal effect. QTLs affecting early and late growth were generally distinct, mapping to different chromosomal locations indicating separate genetic and physiological systems for early and later murine growth.
Subject(s)
Growth/genetics , Age Factors , Animals , Body Weight/genetics , Chromosome Mapping , Crosses, Genetic , Female , Genetic Variation , Male , Mice , Mice, Inbred StrainsABSTRACT
A simple method, using urine collectors, was devised to obtain sufficient and reliable samples of urine from infants (0-4 years old) for the quantitative diagnosis of urinary schistosomiasis. The use of urine collectors is readily accepted by rural populations and it avoids possible interchange between young children. Urine collection and examination from as many as 100 infants can be undertaken daily by a small, well-trained survey team. Our present observations on S. haematobium among infants in Niger show surprisingly high (14.06 per cent) prevalence rates and suggest that this age group may play a considerable role in the transmission of the infection in some endemic foci.
