JDR JDR Most Read Articles
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dohmoto, A.
Right arrow Articles by Maeda, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dohmoto, A.
Right arrow Articles by Maeda, T.
J Dent Res 81(7): 501-504, 2002
© 2002 International and American Associations for Dental Research

RESEARCH REPORT
Biological

Quantitative Trait Loci on Chromosomes 10 and 11 Influencing Mandible Size of SMXA RI Mouse Strains

A. Dohmoto, K. Shimizu, Y. Asada, and T. Maeda,*

Department of Pediatric Dentistry, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan;

* corresponding author, maeda{at}mascat.nihon-u.ac.jp


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS & METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Predicting the mandible size before the termination of growth of the maxillofacial bones is essential in pedodontics as well as for the predictions needed for genetic analysis. Here, Quantitative Trait Locus (QTL) analysis was used to detect the chromosomal regions responsible for the mandible length between the menton and gonion in an SMXA recombinant inbred strain of mice. Around the region 60 cM from the centromere in chromosome 10, the logarithm of the odds score showed a higher than suggestive level. Around the regions 13 cM and 16 cM in chromosome 11, two significant QTLs were detected. Analysis of genotypes from loci corresponding to those QTLs revealed a large mandible when the region between the markers Hba and D11Mit163 and D10Mit70 and D10Mit136 indicated the genotype from the A/J and SM/J alleles, respectively. These results suggest that the major gene(s) responsible for mandible length are located in these regions.

KEY WORDS: mandible length • QTL analysis • SMXA recombinant inbred strain


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS & METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The analysis of mandible shape has long been utilized for strain identification by discriminant analysis (Festing, 1972). In such studies, 11 to 13 measurement points set on the outline of the mandible are used for the characterization of mandible shape. Statistical analysis is carried out for the identification of the strain or sub-line (Goto et al., 1993). However, genetic analysis has not been added to the discriminant analysis.

Previous research has suggested that the effects of genes on the mandible should be spatially patterned (Klingenberg et al., 2001). Signaling interactions coordinate the outgrowth of the facial primordia from buds of undifferentiated mesenchyme into the intricate series of bones and cartilage structures that, together with muscle and other tissues, form the adult face (Francis-West et al., 1998). The relationship between phenotypes and the genes responsible for the mandible shape is difficult to reveal, because polygenes are involved during facial development, including the growth of the mandible. Quantitative trait locus (QTL) analysis has been very successful in identifying chromosomal regions, with quantitative effects depending on the polygene such as body weight, alcoholism susceptibility, etc. (Nadeau and Frankel, 2000; Cheverud et al., 2001).

Recombinant inbred (RI) strains of mice are valuable tools for the study of complex traits such as body weight (Liu et al., 2001). RI strains are derived from systematic inbreeding of randomly selected pairs of the F2 generation of a cross between two different inbred strains of mice. The SMXA RI strain is an existing RI strain derived from the mouse SM/J and the mouse A/J strains as progenitor strains. Both strains have been well-characterized and show differences in a variety of phenotypes, such as body weight (Nishimura et al., 1995). Presently, 26 SMXA RI strains have been generated (Mori et al., 1998). When RI strains are taken as a set, the segregation and gene mapping of a given trait can be analyzed based on the linkage of known marker genes (Anunciado et al., 2000).

In this study, the focus is on the identification of the chromosomal regions involved in the regulation of the anteroposterior length of the mandible, as indicated by the distance between the sites corresponding to the menton and the gonion. We report on the genetic analysis of mandible size in the SMXA RI strain using QTL analysis.


   MATERIALS & METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Mice
A total of 230 mice obtained from parental strains (5 males and 5 females of each of A/J and SM/J) and 21 out of the 26 SMXA RI strains (5 males and 5 females of each of the 21 RI strains) was used. Five SMXA RI strains (SMXA-3, -6, -11, -21, and -23) were excluded from this study due to an insufficient number of samples being available. All mice were obtained from the Institute for Experimental Animals, Hamamatsu University School of Medicine (Hamamatsu, Japan), and were maintained under conventional conditions: 25 ± 2°C, 55 ± 5% humidity, and 12L/12D light. The mice were fed a commercial diet (MR Breeder, Nihon Nohsan Co., Kanagawa, Japan) and tap water ad libitum. The animal-use protocol in this study was reviewed and approved by the Nihon University Institutional Review Board.

Preparation and Measurement of Mandibles
The mice used were 90 days old, and each was anesthetized with ether immediately before death. The heads were soaked in 10% KOH at 43°C for 48 hrs, and the soft tissue was removed. The mandible bones were then washed with water and dried.

The left and right sides of the dried mandible were put on sectional paper with a 1 mm graduation, and the size of the mandible was scaled up to double its original size by means of a duplicator (Canon Co., Japan). The distance between the menton and gonion points was measured as shown in Fig. 1Go. From these results, the mean values in the left and right sides of the mandibles of each strain were calculated.



View larger version (13K):
[in this window]
[in a new window]
  		Figure 1. Measurement landmarks on the mandible. Outline of a mouse mandible showing the 2 landmark points that were measured. The point located at the anterior region is the menton and that at the posterior region is the gonion.

 
QTL Analysis
The Strain Distribution Pattern (SDP) of 789 polymorphic markers reported in a previous study (Mori et al., 1998) was used in the QTL analysis, but because of the clustering of the marker loci, the net number of loci showing a different SDP was 400. Interval mapping was performed with the use of Map Manager QT b28 (Manly, 1993). With the results of interval mapping, the Likelihood Ratio Statistic may be obtained, a value of additive effect and trait variance. At each marker locus, the significance of the trait association was tested by the logarithm of the odds (LOD) statistic. We obtained the LOD score by dividing the Likelihood Ratio Statistic by 4.605 (Anunciado et al., 2000). The significance threshold for the genome-wide scan was computed by means of a permutation test with 1000 permutated datasets (Doerge and Churchill, 1996). The permutation test is a method of establishing the significance of the Likelihood Ratio Statistic generated by interval mapping. As a result of these tests, the LOD scores used for detecting suggestive/significant associations for the mandible length were 2.2/3.8 in males and 2.3/4.0 in females.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Measurements of Mandible Size in Each Strain
The mean values of the menton-gonion measurements in each strain are shown in Fig. 2Go. The mandible was extremely large in males of the SMXA-25 strain (18.2 ± 0.1 mm) and small in females of the SMXA-1 strain (15.7 ± 0.1 mm). For the mean values for males and females, the mandible was large in A/J (17.9 ± 0.1 mm) and small in SM/J (15.9 ± 0.2 mm). The mandible sizes formed a continuous size distribution.



View larger version (56K):
[in this window]
[in a new window]
  		Figure 2. Distribution of the mandible sizes in 21 of the SMXA RI strains and 2 parental strains (SM/J and A/J). The bars colored black, white, and gray indicate data from the means of males (n = 5), females (n = 5), and males and females (n = 10), respectively. The histogram is arranged in order of increasing mean sizes. The data represent means ± SD. The mandible size in the Fig. is scaled up to double the actual size (see MATERIALS & METHODS).

 
QTL Analysis
Fig. 3Go shows the results of the QTL analysis for mandible length. Three suggestive QTLs and two significant QTLs were detected in males and females. Around the region 60 cM from the centromere in chromosome 10, the LOD score showed a higher than suggestive level (LOD, 2.9; additive effect, 0.43; trait variance, 40% in females). The 95% confidence interval was located between the markers D10Mit2 and D10Mit14.



View larger version (38K):
[in this window]
[in a new window]
  		Figure 3. Plot of the LOD scores on chromosome 11 (A) and chromosome 10 (B). Shown in solid lines are the QTL data from males, and in the dotted lines are data from females. The vertical lines represented by the numeric values of 2.2, 2.3, and 4.0 indicate the suggestive levels in males, in females, and the significant levels in females, respectively. The top of the Fig. represents the centromere, and the bottom of the Fig. represents the telomere along the markers. Two significant QTLs in female and 2 suggestive QTLs are detected in the proximal region of chromosome 11 (A). In the distal region of chromosome 10, the suggestive QTL is detected in females (B). The map position in this Fig. represents the distance between the centromere and the marker that is near the peak LOD score.

 
In the proximal region of chromosome 11, two significant QTLs were detected in females. The first peak LOD score was located at the region 13 cM from the centromere between the markers D11Mit152 and Hba, and the second peak LOD score was located at the region 16 cM between the markers D11Mit229 and D11Mit163. These regions correspond to the 95% confidence interval. The LOD scores were 5.1 at the two peaks in females (additive effect, -049; trait variance, 66%). The LOD scores from males, 2.6 and 2.3 at the two peaks, indicate suggestive levels in the same regions of chromosome 11 (additive effect, -032; trait variance, 36%). Significant or suggestive QTLs were not obtained in the other chromosomes.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
We have reported that F1 mice obtained by the crossbreeding of mice with small and large mandibles showed the characteristics of the parent strain mice with larger mandibles. From measurement of 24 reference points in the mandible, the distance between the menton and gonion showed a significant dominant inheritance compared with other distances between reference points. This finding suggests that the distance between the menton and gonion was available as a phenotype for analyzing the genes that determined mandible length (Okamoto et al., 1997).

The SDP corresponding to this genotype was reported in a previous study (Mori et al., 1998). Fig. 4Go shows the genotypes in the proximal region of chromosome 11. The genotypes of SMXA-12, -1, -24, -29, -4, -27, -15, -10, and –19 were derived from the SM/J allele between the markers Hba and D11Mit163. These SMXA RI strains showed a small or intermediate-sized mandible. Moreover, the SMXA RI strains show a large mandible (SMXA-7, -26, -25, and –30), indicating genotypes derived from the A/J allele in the same region except for the locus of D11Mit229. These results suggest that the major gene(s) responsible for mandible length were located in the region between markers Hba and D11Mit163, a distance that was 3 cM, except at D11Mit229.



View larger version (85K):
[in this window]
[in a new window]
  		Figure 4. Strain distribution pattern (SDP) of chromosome 10 (A) and chromosome 11 (B) around the peak LOD scores. Genetic and microsatellite marker loci around the peak LOD scores are listed at the left side. Each column represents a genotype identified in each SMXA RI strain mouse. The black box indicates the A/J alleles, the white box indicates the SM/J allele, and the gray box indicates that the genotype was not determined.

 
In chromosome 10 of the SMXA-26, -7, and –30, which had large mandibles, it was indicated that the genotype was derived from the SM/J allele. In the SMXA-1, -4, and –12, which had small mandibles, it was indicated that the genotype was derived from the A/J allele between the markers D10Mit70 and D10Mit136. The effect of this region was opposite that of chromosome 11. The SM/J allele on chromosme 10 for the QTL is associated with a large mandible size.

The mandible size was determined not only by genes located in chromosomes 10 and 11, since there were also several effects that were weak in other chromosomes. Because the number of strains in an RI set is limited in the mouse (26 strains for the SMXA), with use of a more stringent {alpha} level (which reduces the acceptable false-positive risk; {alpha} = 0.0001), only effective QTLs were detected in this study (Belknap et al., 1996).

The Mouse Genome Database (http://www.informatics.jax.org/) was searched for candidate genes according to their position at around 60 cM of chromosome 10 and between 13 cM and 16 cM of chromosome 11. The Mouse Genome Database scan revealed more than 10 genes as candidates for mandible size in chromosomes 10 and 11 (for example, Syt, Myf5, Myf6, Kera, Lum, Kcnc2, and Kifc4b on chromosome 10; Mor2, Otx1, Cct4, Spnb2, Gek1 Hba, and Stk10 on chromosome 11). It is of interest that a candidate gene near the QTL for mandible size on chromosome 11 is Otx1 (orthodenticle), a gene highly related to Otx2. Mouse embryos homozygous for a knockout allele of Otx2 display a striking phenotype in which the entire brain rostral to rhombomere 3 is missing (Ang et al., 1996). This clearly demonstrates the importance of this gene in rostral head development. The knockout mice of Otx1 display a less severe phenotype, but nonetheless indicate a critical role for Otx1 in vertebrate head development (Acampora et al., 1997). Interestingly, Otx1 is also post-natally transcribed and translated in the pituitary gland. Cell culture experiments indicate that Otx1 may activate transcription of the growth, follicle-stimulating, and luteinizing hormones, and of {alpha}-glycoprotein subunit genes (Acampora et al., 1998). These studies and the results in this study suggest that Otx1 is a potential candidate for the gene controlling mandible size.

The positions around 60 cM of the mouse chromosome 10 and between 13 cM and 16 cM of the mouse chromosome 11 correspond to regions 12q21 and 2p13 in human chromosomes, respectively. In this study, the experimental conditions were simplified by use of the SMXA RI strain whose chromosome was homozygous. If the result of this study is to be applied to clinical diagnoses, the effects of heterozygous chromosomes must be analyzed. However, focus can be placed on the two chromosomal regions 12q21 and 2p13. It might be possible to predict the mandible size of a patient before the termination of the growth of the maxillofacial bones by searching for the polymorphisms of these chromosomal regions, whether derived from large or small mandibles.


   ACKNOWLEDGMENTS
 
We thank Dr. M. Nishimura (Hamamatsu University School of Medicine) for providing the SMXA RI strain mice. We also thank the members of the Department of Pediatric Dentistry for helpful discussions. This work was supported by a grant from Research for Frontier Science (The Ministry of Education, Science, Sports and Culture).

Received November 12, 2001; Last revision May 6, 2002; Accepted May 15, 2002


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS & METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Acampora D, Avantaggiato V, Tuorto F, Simeone A (1997). Genetic control of brain morphogenesis through Otx gene dosage requirement. Development 124:3639–3650.[Abstract]

Acampora D, Mazan S, Tuorto F, Avantaggiato V, Tremblay JJ, Lazzaro D, et al. (1998). Transient dwarfism and hypogonadism in mice lacking Otx1 reveal prepubescent stage-specific control of pituitary levels of GH, FSH and LH. Development 125:1229–1239.[Abstract]

Ang SL, Jin O, Rhinn M, Daigle N, Stevenson L, Rossant J (1996). A targeted mouse Otx2 mutation leads to severe defects in gastrulation and formation of axial mesoderm and to deletion of rostral brain. Development 122:243–252.[Abstract]

Anunciado RV, Ohno T, Mori M, Ishikawa A, Tanaka S, Horio F, et al. (2000). Distribution of body weight, blood insulin and lipid levels in the SMXA recombinant inbred strains and the QTL analysis. Exp Anim 49:217–224.[Medline]

Belknap JK, Mitchell SR, O'Toole LA, Helms ML, Crabbe JC (1996). Type I and type II error rates for quantitative trait loci (QTL) mapping studies using recombinant inbred mouse strains. Behav Genet 26:149–160.[Medline]

Cheverud JM, Vaughn TT, Pletscher LS, Peripato AC, Adams ES, Erikson CF, et al. (2001). Genetic architecture of adiposity in the cross of LG/J and SM/J inbred mice. Mamm Genome 12:3–12.[Medline]

Doerge RW, Churchill GA (1996). Permutation tests for multiple loci affecting a quantitative character. Genetics 142:285–294.[Abstract]

Festing M (1972). Mouse strain identification. Nature 238:351–352.[Medline]

Francis-West P, Lander R, Barlow A, Graveson A (1998). Signaling interactions during facial development. Mech Dev 75:3–28.[Medline]

Goto N, Yamaoka A, Sudo T, Mannen H, Fukuta K, Nishimura M (1993). Morphometric profiles of the mandible of SMXA recombinant inbred strains of mice and strain identification on the basis of mandible measurements. Jikken Dobutsu 42:41–50.[Medline]

Klingenberg CP, Leamy LJ, Routman EJ, Cheverud JM (2001). Genetic architecture of mandible shape in mice: effects of quantitative trait loci analyzed by geometric morphometrics. Genetics 157:785–802.[Abstract/Free Full Text]

Liu X, Oliver F, Brown SD, Denny P, Keightley PD (2001). High-resolution quantitative trait locus mapping for body weight in mice by recombinant progeny testing. Genet Res 77:191–197.[Medline]

Manly KF (1993). A Macintosh program for storage and analysis of experimental genetic mapping data. Mamm Genome 4:303–313.[Medline]

Mori M, Akiyoshi S, Mizuno Y, Okuizumi H, Okazaki Y, Hayashizaki Y, et al. (1998). Genetic profile of the SMXA recombinant inbred mouse strains revealed with restriction landmark genomic scanning. Mamm Genome 9:695–709.[Medline]

Nadeau JH, Frankel WN (2000). The roads from phenotypic variation to gene discovery: mutagenesis versus QTLs. Nat Genet 25:381–384.[Medline]

Nishimura M, Hirayama N, Serikawa T, Kanehira K, Matsushima Y, Katoh H, et al. (1995). The SMXA: a new set of recombinant inbred strain of mice consisting of 26 substrains and their genetic profile. Mamm Genome6:850–857.[Medline]

Okamoto K, Dohmoto A, Takei K, Ohta T, Komiya J, Matsubara K, et al. (1997). Study on hereditary pattern of the mandible shape in multiple models of inbred mouse strains. Jpn J Pediatr Dent 35:410–414.




This article has been cited by other articles:


Home page
 J. Dent. Res.Home page
J. Oh, C.J. Wang, M. Poole, E. Kim, R.C. Davis, I. Nishimura, and E.-K. Pae
A Genome Segment on Mouse Chromosome 12 Determines Maxillary Growth
J. Dent. Res., December 1, 2007; 86(12): 1203 - 1206.
[Abstract] [Full Text] [PDF]

Home page
 GeneticsHome page
T. Kimura, A. Shimada, N. Sakai, H. Mitani, K. Naruse, H. Takeda, H. Inoko, G. Tamiya, and M. Shinya
Genetic Analysis of Craniofacial Traits in the Medaka
Genetics, December 1, 2007; 177(4): 2379 - 2388.
[Abstract] [Full Text] [PDF]

Home page
 J. Dent. Res.Home page
T. Shimizu, H. Oikawa, J. Han, E. Kurose, and T. Maeda
Genetic Analysis of Crown Size in the First Molars Using SMXA Recombinant Inbred Mouse Strains
J. Dent. Res., January 1, 2004; 83(1): 45 - 49.
[Abstract] [Full Text] [PDF]

Home page
 Crit. Rev. Oral Biol. Med.Home page
I. Nishimura, T. A. Drake, A. J. Lusis, K. M. Lyons, J. H. Nadeau, and J. Zernik
ENU LARGE-SCALE MUTAGENESIS AND QUANTITATIVE TRAIT LINKAGE (QTL) ANALYSIS IN MICE: NOVEL TECHNOLOGIES FOR SEARCHING POLYGENETIC DETERMINANTS OF CRANIOFACIAL ABNORMALITIES
Crit. Rev. Oral. Biol. Med., September 1, 2003; 14(5): 320 - 330.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dohmoto, A.
Right arrow Articles by Maeda, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dohmoto, A.
Right arrow Articles by Maeda, T.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
IADR Journals Advances in Dental Research ®
Journal of Dental Research ® Critical Reviews (1990-2004)