TABLE 2.
Effects of QTL genotype on phenotype, gene expression, and circulating IGFBP levels in 6-week-old mice segregating only for a four-gene region
| Genotype
|
|||
|---|---|---|---|
| DBA homozygote | Heterozygote | C57 homozygote | |
| Phenotypes | 23 | 14 | 9 |
| Tail length (mm) | 72.8 ± 0.4 | 74.3 ± 0.6 | 75.2 ± 0.8 |
| Body mass (g) | 17.6 ± 0.3 | 18.2 ± 0.5 | 19.1 ± 0.7 |
| Expression levelsa | 24 | 14 | 10 |
| PAPPA2 (probe a) | 1.18 ± 0.09 | 1.05 ± 0.14 | 0.78 ± 0.18 |
| PAPPA2 (probe b) | 1.48 ± 0.08 | 1.55 ± 0.13 | 1.21 ± 0.16 |
| IGFBP-5 | 1.07 ± 0.03 | 1.03 ± 0.05 | 1.05 ± 0.06 |
| β-actin | 17.81 ± 0.06 | 17.86 ± 0.10 | 17.66 ± 0.12 |
| Circulating protein levels | 18 | 5 | 13 |
| IGFBP-2b | 15.2 ± 0.8 | 14.0 ± 2.0 | 14.0 ± 1.1 |
| IGFBP-3b | 13.0 ± 0.9 | 11.8 ± 2.1 | 8.7 ± 1.1 |
| IGFBP-4b | 5.7 ± 0.3 | 6.5 ± 0.7 | 5.5 ± 0.4 |
| IGFBP-5 (ng/ml) | 22.6 ± 1.6 | 30.2 ± 3.9 | 15.9 ± 2.1 |
Numbers in the same row as each category name indicate sample sizes. Traits for which there are significant differences between genotypes are underlined. For all traits, values are least squares means ± standard errors from a general linear model including genotype and pair.
Normalized values for PAPPA2 and IGFBP-5 are expressed relative to a standard RNA pool made up of many samples; e.g., a value of 1.5 indicates levels 50% higher than those of the standard pool. Ct values are provided for β-actin.
Circulating protein levels for IGFBP-2, IGFBP-3, and IGFBP-4 were measured using IGF-binding activity and are expressed in arbitrary units.