| First Author | Moutier R | Year | 1993 |
| Journal | Mouse Genome | Volume | 91 |
| Issue | 3 | Pages | 569-571 |
| Mgi Jnum | J:14808 | Mgi Id | MGI:62969 |
| Citation | Moutier R, et al. (1993) A discontinuous variation in laboratory mouse mandible measurements. Mouse Genome 91(3):569-571 |
| abstractText | Full text of Mouse Genome contribution: A DISCONTINUOUS VARIATION IN LABORATORY MOUSE MANDIBLE MEASUREMENTS. R Moutier and B. Martin. Laboratoire Genetique, Neurogenetique et Comportement, URA 1294 CNRS, UFR Biomedicale, 45 rue des Saints-Peres, 75270 Paris cedex 06, FRANCE. The mouse mandible is a complex morphological structure. The adult shape results from interactions between a polygenic system and environmental influences. However the achieved adult pattern appears remarkably constant and useful for the characterization of most inbred strains (1). Only one gene of this polygenic system has been so far identified (2). The present paper deals with the analysis of measurement 9, among the eleven measurements defined by Festing (1), in eight inbred and three Fl hybrid strains. Materials and Methods The 8 inbred strains used in this study were: A/Orl (A), BALB/cOrl (C), CBA/HOrl (H), C57BL/60rl (B6), NZB/BlOrl (N), XLII/Orl (XL) obtained from the CNRS Breeding Center, Orleans, France, and C57BL/l0Bg (Bl0), DBA/lBg (Dl) from Behavioral Genetics Laboratory, University of Connecticut, USA. Three Fl crosses, AXLF1, CAF1 and XLB6F1, have been obtained from the parental crosses, respectively A female x XL male, C female x A male and XL female x B6 male. The mandibles were obtained from both female and male mice between 8 and 9 weeks of age and prepared according to the method of Festing (1). Data were corrected for size by adding all eleven measurements and expressing each measurement P1-P11 as a percentage of the total. Results Survey of 7 parental inbred strains for measurement P9: Means and standard deviations of mandible measurement P9 for 7 inbred strains are presented Table 1. The ANOVA analysis shows a significant strain effect (F6,126= 38.90, p<0.0001), a significant sex effect (F1,126=4.17, p<0.05), and a significant strain x sex interaction (F6,126=2.47, p<0.03). The sex effect and strain x sex interaction result from 2 strains with significant P9 sexual dimorphism: the A strain (t=2.61, p<0.02) and the H strain (t=3.06, p<0.003). Pair-comparisons of strains for P9 means (t test) allow the 7 inbred strains to be classified in 2 non-overlapping groups; the ÒlowÓ strains: B10, Dl, H and XL with mean P9 values lower than 14.09, and the ÒhighÓ strains: A, C, and N with mean P9 values higher than 14.30. Contrast analysis between these 2 groups show significant differences either with the strain factor alone (Fl,126=216.33, p<0.000l) or with both strain and sex as factors (F2,126=110.25, p<0.0001). Means and standard deviations of mandible measurement P9 obtained for the B6 strain are 14.05 +/- 0.09 in females (n=19) and 14.01 +/- 0.11 in males (n=17). Results obtained for Fl hybrid strains: Means and standard deviations of mandible measurement P9 for the Fl hybrids AXLF1, CAF1 and XLB6F1 are presented Table 2. The ANOVA analysis shows a significant strain effect (F2,78=48.64, p<0.0001), a significant sex effect (Fl,78=6.79, p<0.02), and a significant strain x sex interaction (F2,78=3.23, p<0.05). The sex effect and strain x sex interaction result from the XLB6F1 strain showing a significant P9 sexual dimorphism. Pair comparisons of strains show that the AXLF1 and CAF1 strains with mean P9 values higher than 14.28 range into the same group and are significantly different from both the XLB6F1 female and male groups with mean P9 values lower than 14.08. "low" strains: B10: X: female (n): 14.01 (10); SD: female (n): 0.11; male (n): 14.01 (10); SD: male (n): 0.10; "high" strains: A: X: female (n): 14.40 (10); SD: female (n): 0.14; male (n): 14.56 (10); SD: male (n): 0.15. "low" strains: D1: X: female (n): 14.09 (10); SD: female (n): 0.16; male (n): 14.03 (10); SD: male (n): 0.18; "high" strains: C: X: female (n): 14.32 (10); SD: female (n): 0.12; male (n): 14.34 (10); SD: male (n): 0.14. "low" strains: H: X: female (n): 13.89 (10); SD: female (n): 0.11; male (n): 14.07 (10); SD: male (n): 0.09; "high" strains: N: X: female (n): 14.30 (10); SD: female (n): 0.20; male (n): 14.41 (10); SD: male (n): 0.15. "low" strains: XL: X: female (n): 14.09 (10); SD: female (n): 0.19; male (n): 14.03 (10); SD: male (n): 0.11. Table 1. Mean length (X) and standard deviation (SD) as a percentage of overall size for the P9 measurement in 7 inbred strains. Discussion The Figure 1 summarizes these results which show that the parental and the F l hybrid strains can be divided into two groups "high" and "low", according to the P9 measurement. The B6 and B10 strains which are closely related substrains (3), show no significantly different P9 mean values, so that B6 (like B10) can be classified as a "lowÓ strain. By crossing two "high" strains such A and C, Fl hybrids showing high P9 measurements are obtained; by crossing a "high" strain (A) and a "low" strain (XL) "high" P9 hybrids also are obtained, suggesting some dominance of the "high" determinant. By crossing two ÒlowÓ strains such B6 and XL, Fl hybrids showing low P9 measurements are obtained. In a former study using the same method, Lovell et al. (4) reported mandible measurement values for different inbred and one Fl hybrid strains. We observe that their P9 values are in good agreement with ours: C57BL/6J and DBA/2J, (DBA/2 and DBA/1 being two closely related substrains), have low P9 values (ranging from 13.85 to 14.13), and BALB/cJ as our BALB/c strain, a high P9 value (14.55). Fl hybrids from a cross between C57BL/6J and DBA/2J show low P9 values (13.94-13.96), confirming that crossing two parental "low" strains provides Fl hybrids with a low P9 value. Measurement 9 is one of the largest dimensions of the mandible. It is composed of both the anterior mandible length and part of the posterior mandible length up to the junction of the angular and condylar processes. The repartition of the studied inbred strains in two non-overlapping groups according to this measurement, and the stability of the structure transmitted to Fl hybrids when two strains of the same group are crossed together, suggest the existence of two fundamental types in the organization of the laboratory mouse mandible. The study of backcross generations and recombinant inbred strains from crosses between "high" and "low" parental strains will confirm this hypothesis and elucidate the mode of inheritance of the two mandible types. AXLF1: X: female (n): 14.28 (21); male (n): 14.31 (26); SD: female (n): 0.08; male (n): 0.10. CAF1: X: female (n): 14.35 (10); male (n): 14.35 (12); SD: female (n): 0.09; male (n): 0.07. XLB6F1: X: female (n): 13.99 (12); male (n): 14.08 (11); SD: female (n): 0.08; male (n): 0.09. Table 2. Mean length (X) and standard deviation (SD) as a percentage of overall size for the P9 measurement in Fl hybrid strains. Figure 1. (Legend). Distribution of the P9 measurement in some inbred and Fl hybrid strains of mice. Acknowledgements. This work was supported by CNRS URA 1294, MEN. (Universite Paris V), UFR Biomedicale and La Fondation pour la Recherche Medicale. The authors wish to thank Catherine Marchaland and Fernando Perez Diaz for assistance with statistical analysis, and John Paddy Phillips for improving the English text. References 1. Festing MFW, 1972. Nature 238: 351-352. 2. Bailey DW, 1986. J Craniof Genet Develop Biol 2: 33-39. 3. Festing MFW and Roderick TH, 1989. Genet Res 53: 45-55. 4. Lovell DP, Johnson FM, and Willis DB, 1986. Am J Anat 176:287-303. |
