| First Author | Di Masso RJ | Year | 1997 |
| Journal | Mouse Genome | Volume | 95 |
| Issue | 4 | Pages | 882-85 |
| Mgi Jnum | J:45471 | Mgi Id | MGI:1195492 |
| Citation | Di Masso RJ, et al. (1997) Identification of mouse lines selected for body conformation using the morphometric profile of the mandible. Mouse Genome 95(4):882-85 |
| abstractText | Full text of Mouse Genome contribution: Identification of mouse lines selected for body conformation using the morphometric profile of the mandible. R. J. Di Masso, C.M. Zerpa and M.T. Font; Institute de Genetica Experimental - Facultad de Ciencias Medicas Santa Fe 3100 - 2000 Rosario -Argentina. The morphometric profile of the mandible is a heritable quantitative trait (1) that can be used as an accurate means of identifying different inbred strains of mice (2). The objective of the present study was to distinguish a set of mouse lines artificially selected for body conformation (3), on the basis of the morphometric profiles of their mandibles. These lines resulted from a selective procedure that has been extremely useful in the investigation of body morphometric traits and femoral histomorphometry (4), bone mineral deposition (5) and bone biomechanics (6). Materials and Methods Four lines of mice divergently selected for body conformation (3) by means of a quantitative index which combines body weight and tail length at 49 days of age, and the unselected control line (CBi) were used. Two lines were generated favoring the positive phenotypic correlation between both traits (agonistic selection: CBi-, low body weight-short tail; CBi+, high body weight-long tail) while the other two were derived by selection against the aforementioned association (antagonistic selection: Cbi/L, low body weight-long tail; CBi/C, high body weight-short tail). Lines were inbred through a restriction on the population size being their average inbreeding coefficient approximately 0.90. Mice used in this study were contemporaneously bred in the same mouse room on a 12-hour-on/12 hour-off light cycle and received the same diet of pelleted mouse food (Cargill) and water ad libitum. The mandibles were obtained from both female and male mice (n = 10 individuals per genotype-sex group) of 15 weeks of age and prepared according to the method of Festing (2). A total of 11 measurements (7) (Figure 1) were taken on each right mandible. The effects of genotype, sex and (genotype x sex) interaction were evaluated using a two-way analysis of variance. Data were also analyzed by the multivariate techniques of principal components (PCA) and discriminant analysis. Results Means +/- SE of mandible measurements for males and females are presented in Tables 1 and 2. The ANOVA analysis shows a significant (p<0.001) genotype effect for all the measurements, a significant sex effect for measurements 1, 7, 8, and 11 (p<0.001) and 9 (p<0.05) and a non significant genotype x sex interaction (p>0.05). For the sexual dimorphic characters, females showed larger mandibles than males (measurements 7, 8, 9 and 11) while males showed wider mandibles than females (measurement 1). Table 3 shows the results of principal component analysis applied to mandible measurements in males and females. The two first principal components (PC1 and PC2) account for 80.8% and 83.4% of morphometrical variation information in each sex. In PC1 all the eigenvectors were negative and could be interpreted as a size factor. In PC2 eigenvectors of width measurements were positive while those related with length measurements were negative, so it can be interpreted as a form factor. CBi- and CBi+ mice mainly differed in the length of their mandibles. Negative selected mice (CBi-) showed shorter and wider mandibles than animals with positive selection (CBi+). Control mice (CBi) presented intermediate values. CBi/C mandibles tend to be wider than in CBi/L. Mice with positive selection for body weight (CBi/C and CBi+) showed a clear tendency towards bigger mandibles than the other genotypes and differences between them were mainly due to width measure- ments being CBi/C mandibles shorter and wider than Cbi+ mandibles.Table 4 presents the results of a classification analysis by means of discriminant functions. Almost all the mice were correctly identified except one Cbi/L male, one CBi male and one CBi+ female (rate of misclassification: males 4%; females 2%). Discussion The genetic profile of an inbred line of mice, defined as the particular assembly of genes that distinguishes it from other lines, can be assessed by means of morphological, biochemical or immunological markers. Univariate analysis of a set of mandible measurements, in mice selected for body conformation combining as selective criterion a measure of total biomass (body weight) and an estimation of skeletal length (tail length), evinced some particularities in the mandible morphogenesis of these genotypes. The results of principal component analyses revealed differences in the size and shape of the mandible among genotypes. Based on these differences, line identification appeared to be possible by a discriminant analysis using mandible measurements with a low probability of wrong discrimination. Although further identification would be needed to confirm the genetic uniformity of these lines using other methods such as biochemical marker gene analysis, the results herein described confirm the feasibility to identify them using mandible analysis. References 1. Bailey DW, 1985. J Heredity 76: 107-114. 2. Festing MFW, 1972. Nature 238: 351-352. 3. Di Masso RJ, Abdala SB, Sanchez SM and Font MT, 1991. Mendeliana 9: 79-92. 4. Di Masso RJ, Celoria GC and Font MT, 1991. Bone Miner 15: 209-218. 5. Di Masso RJ and Font MT, 1993. Bone Miner 23: 49-56. 6. Di Masso RJ, Font MT, Capozza RF, Detarsio G, Sosa F and Ferretti JL, 1997. Bone 20: 539-545. 7. Lovell DP and Totman P, 1984. Genet. Res.: 65-73. Fig. 1. (Legend). Diagram of the right mandible showing the eleven measurements made on each mandible in this study (Mandible measurements X1-X6: height from the X axis to the horizontal dotted line at each site; X7-X11: length from the Y axis to the vertical dotted line at each site). Table 1. (Legend). Mean +/- standard error (mm) for each mandible measurement in male mice. 1: CBi-: 0.679 +/- 0.071; CBi+: 0.876 +/- 0.092; CBi: 0.748 +/- 0.047; CBi/C: 0.926 +/- 0.089; CBi/L: 0.812 +/- 0.073. 2: CBi-: 2.071 +/- 0.115; CBi+: 2.264 +/- 0.075; CBi: 0.235 +/- 0.122; CBi/C: 2.404 +/- 0.075; CBi/L: 2.338 +/- 0.101. 3: CBi-: 2.875 +/- 0.109; CBi+: 3.245 +/- 0.083; CBi: 3.035 +/- 0.199; CBi/C: 3.366 +/- 0.134; CBi/L: 3.226 +/- 0.142. 4: CBi-: 4.829 +/- 0.147; CBi+: 5.308 +/- 0.113; CBi: 5.114 +/- 0.161; CBi/C: 5.447 +/- 0.165; CBi/L: 4.856 +/- 0.139. 5: CBi-: 5.521 +/- 0.155; CBi+: 6.109 +/- 0.128; CBi: 5.986 +/- 0.159; CBi/C: 6.307 +/- 0.161; CBi/L: 5.882 +/- 0.191. 6: CBi-: 6.042 +/- 0.181; CBi+: 6.782 +/- 0.079; CBi: 6.471 +/- 0.207; CBi/C: 6.682 +/- 0.269; CBi/L: 6.195 +/- 0.174. 7: CBi-: 8.383 +/- 0.233; CBi+: 9.581 +/- 0.251; CBi: 9.183 +/- 0.219; CBi/C: 8.911 +/- 0.196; CBi/L: 9.111 +/- 0.158. 8: CBi-: 8.714 +/- 0.308; CBi+: 10.041 +/- 0.399; CBi: 9.679 +/- 0.257; CBi/C: 9.258 +/- 0.195; CBi/L: 9.545 +/- 0.222. 9: CBi-: 10.213 +/- 0.259; CBi+: 11.518 +/- 0.204; CBi: 10.921 +/- 0.234; CBi/C: 10.994 +/- 0.164; CBi/L: 10.939 +/- 0.167. 10: CBi-: 11.892 +/- 0.315; CBi+: 13.194 +/- 0.188; CBi: 12.671 +/- 0.275; CBi/C: 12.772 +/- 0.149; CBi/L: 12.638 +/- 0.315. 11: CBi-: 12.025 +/- 0.237; CBi+: 12.317 +/- 0.271; CBi: 12.966 +/- 0.197; CBi/C: 12.761 +/- 0.179; CBi/L: 12.857 +/- 0.184. Table 2. (Legend). Mean +/- standard error (mm) for each mandible measurement in female mice. 1: CBi-: 0.561 +/- 0.047; CBi+: 0.779 +/- 0.061; CBi: 0.623 +/- 0.039; CBi/C: 0.834 +/- 0.052; CBi/L: 0.685 +/- 0.111. 2: CBi-: 2.105 +/- 0.115; CBi+: 2.286 +/- 0.064; CBi: 2.245 +/- 0.085; CBi/C: 2.379 +/- 0.093; CBi/L: 2.351 +/- 0.089. 3: CBi-: 2.904 +/- 0.139; CBi+: 3.289 +/- 0.123; CBi: 3.137 +/- 0.081; CBi/C: 3.381 +/- 0.113; CBi/L: 3.269 +/- 0.141. 4: CBi-: 4.815 +/- 0.188; CBi+: 5.337 +/- 0.113; CBi: 5.186 +/- 0.141; CBi/C: 5.499 +/- 0.157; CBi/L: 4.815 +/- 0.217. 5: CBi-: 5.523 +/- 0.208; CBi+: 6.202 +/- 0.133; CBi: 5.921 +/- 0.132; CBi/C: 6.252 +/- 0.201; CBi/L: 5.854 +/- 0.204. 6: 6.048 +/- 0.248; CBi+: 6.928 +/- 0.202; CBi: 6.447 +/- 0.228; CBi/C: 6.809 +/- 0.349; CBi/L: 6.209 +/- 0.265. 7: CBi-: 8.732 +/- 0.242; CBi+: 9.746 +/- 0.238; CBi: 9.514 +/- 0.269; CBi/C: 9.152 +/- 0.274; CBi/L: 9.129 +/- 0.261. 8: CBi: 9.071 +/- 0.315; CBi+: 10.267 +/- 0.251; CBi: 9.996 +/- 0.264; CBi/C: 9.554 +/- 0.257; CBi/L: 9.694 +/- 0.229. 9: CBi-: 10.376 +/- 0.264; CBi+: 11.481 +/- 0.303; CBi: 11.159 +/- 0.211; CBi/C: 11.128 +/- 0.258; CBi/L: 10.937 +/- 0.203. 10: CBi-: 11.992 +/- 0.268; CBi+: 13.171 +/- 0.288; CBi: 12.772 +/- 0.275; CBi/C: 12.011 +/- 0.261; CBi/L: 12.611 +/- 0.221. 11: CBi-: 12.519 +/- 0.288; CBi+: 13.756 +/- 0.275; CBi: 13.381 +/- 0.274; CBi/C: 13.213 +/- 0.303; CBi/L: 13.074 +/- 0.302. Table 3. (Legend). Eigenvectors of the two first principal components (PC1 and PC2) in male (M) and female (F) mice selected for body conformation. Variable: M: PC1 Ð X1: -0.2509; X2: -0.2513; X3: -0.2472; X4: -0.2751; X5: -0.3126; X6: -0.303; X7: -0.3178; X8: -0.3036; X9: -0.3444; X10: -0.3507; X11: -0.3359. Variable: M: PC2; X1: 0.4517; X2: 0.1828; X3: 0.1324; X4: 0.3717; X5: 0.3074; X6: 0.2395; X7: 0.3754; X8: -0.3968; X9: -0.2158; X10: -0.1331; X11: -0.3041. Variable: F: PC1: X1: -0.2628; X2: -0.2251; X3: -0.2671; X4: -0.2987; X5: -0.3309; X6: -0.3021; X7: -0.2905; X8: -0.2948; X9: -0.3424; X10: -0.3517; X11: -0.3269. Variable: F: PC2: X1: 0.4197; X2: 0.4143; X3: 0.3216; X4: 0.1616; X5: 0.1816; X6: 0.1551; X7: -0.4268; X8: -0.3638; X9: -0.2091; X10: -0.1196; X11: -0.3051. Table 4. (Legend). Clasification by means of discriminant analysis. True genotype: CBi-; Assigned genotype: Sex: M: CBi-: 10; F: CBi-: 10; True genotype: CBi+; Assigned genotype: M: CBi+: 10; F: CBi+: 9; CBi: 1; True genotype: CBi; Assigned genotype: M: CBi: 9; CBi/L: 1; F: CBi: 10; True genotype: CBi/C; Assigned genotype: M: CBi/C: 10; F: CBi/C: 10; True genotype: CBi/L; Assigned genotype: M: CBi: 1; CBi/L: 9; F: CBi/L: 10. |
