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Gupta S, Fernandes R, Natarajan S, Jose NP, Giri J, Dahal S. Comparative evaluation of arch form among the Nepalese population: A morphological study. J Oral Maxillofac Pathol 2024; 28:111-118. [PMID: 38800435 PMCID: PMC11126270 DOI: 10.4103/jomfp.jomfp_280_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 09/20/2023] [Accepted: 10/09/2023] [Indexed: 05/29/2024] Open
Abstract
Aims The study aims to identify sexual dimorphic features in the arch patterns based on tooth arrangement patterns and the maxillary and mandibular arches using Euclidean Distance Matrix Analysis (EDMA). Settings and Design A total of 96 Nepalese subjects, aged 18 to 25 were assessed using casts and photographs. Materials and Methods Thirteen landmarks representing the most facial portions of the proximal contact areas on the maxillary and mandibular casts were digitised. Seventy-eight possible, Euclidean distances between the 13 landmarks were calculated using the Analysis ToolPak of Microsoft Excel®. The male-to-female ratios of the corresponding distances were computed and ratios were compared to evaluate the arch form for variation in the genders, among the Nepalese population. Statistical Analysis Used Microsoft Excel Analysis ToolPak and SPSS 20.0 (IBM Chicago) were used to perform EDMA and an independent t-test to compare the significant differences between the two genders. Results The maxillary arch's largest ratio (1.008179001) was discovered near the location of the right and left lateral incisors, indicating that the anterior region may have experienced the greatest change. The posterior-molar region is where the smallest ratio was discovered, suggesting less variation. At the intercanine region, female arches were wider than male ones; however, at the interpremolar and intermolar sections, they were similar in width. Females' maxillary arches were discovered to be bigger antero-posteriorly than those of males. The highest ratio (1.014336113) in the mandibular arch was discovered at the intermolar area, suggesting that males had a larger mandibular posterior arch morphology. At the intercanine area, the breadth of the arch form was greater in males and nearly the same in females at the interpremolar and intermolar regions. Female mandibular arch forms were also discovered to be longer than those of males from the anterior to the posterior. Conclusions The male and female arches in the Nepalese population were inferred to be different in size and shape. With references to the landmarks demonstrating such a shift, the EDMA established objectively the presence of square arch forms in Nepali males and tapering arch forms in Nepalese females.
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Affiliation(s)
- Simran Gupta
- Intern, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Rhea Fernandes
- Intern, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Srikant Natarajan
- Department of Forensic Odontology, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Nidhin P. Jose
- Department of Orthodontics and Dentofacial Orthopaedics, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Jamal Giri
- Department of Orthodontics, B.P. Koirala Institute of Health Sciences, Dharan, Nepal, India
| | - Samarika Dahal
- Department of Oral Pathology and Forensic Dentistry, Maharajgunj Medical Campus, Institute of Medicine, Nepal, India
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Navarro N, Murat Maga A. Genetic mapping of molar size relations identifies inhibitory locus for third molars in mice. Heredity (Edinb) 2018; 121:1-11. [PMID: 29302051 DOI: 10.1038/s41437-017-0033-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 12/22/2022] Open
Abstract
Molar size in Mammals shows considerable disparity and exhibits variation similar to that predicted by the Inhibitory Cascade model. The importance of such developmental systems in favoring evolutionary trajectories is also underlined by the fact that this model can predict macroevolutionary patterns. Using backcross mice, we mapped QTL for molar sizes controlling for their sequential development. Genetic controls for upper and lower molars appear somewhat similar, and regions containing genes implied in dental defects drive this variation. We mapped three relationship QTLs (rQTL) modifying the control of the mesial molars on the focal third molar. These regions overlap Shh, Sostdc1, and Fst genes, which have pervasive roles in development and should be buffered against new variation. It has theoretically been shown that rQTL produces new variation channeled in the direction of adaptive changes. Our results provide evidence that evolutionary/disease patterns of tooth size variation could result from such a non-random generating process.
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Affiliation(s)
- Nicolas Navarro
- EPHE, PSL Research University Paris, F-21000, Dijon, France. .,Biogéosciences, UMR CNRS 6282, Université Bourgogne Franche-Comté, F-21000, Dijon, France.
| | - A Murat Maga
- Division of Craniofacial Medicine, Department of Pediatrics, University of Washington, Seattle, WA, 98105, USA.,Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, 98101, USA
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Pallares LF, Ledevin R, Pantalacci S, Turner LM, Steingrimsson E, Renaud S. Genomic regions controlling shape variation in the first upper molar of the house mouse. eLife 2017; 6:29510. [PMID: 29091026 PMCID: PMC5679752 DOI: 10.7554/elife.29510] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Accepted: 10/28/2017] [Indexed: 01/25/2023] Open
Abstract
Numerous loci of large effect have been shown to underlie phenotypic variation between species. However, loci with subtle effects are presumably more frequently involved in microevolutionary processes but have rarely been discovered. We explore the genetic basis of shape variation in the first upper molar of hybrid mice between Mus musculus musculus and M. m. domesticus. We performed the first genome-wide association study for molar shape and used 3D surface morphometrics to quantify subtle variation between individuals. We show that many loci of small effect underlie phenotypic variation, and identify five genomic regions associated with tooth shape; one region contained the gene microphthalmia-associated transcription factor Mitf that has previously been associated with tooth malformations. Using a panel of five mutant laboratory strains, we show the effect of the Mitf gene on tooth shape. This is the first report of a gene causing subtle but consistent variation in tooth shape resembling variation in nature.
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Affiliation(s)
- Luisa F Pallares
- Department of Evolutionary Genetics, Max-Planck Institute for Evolutionary Biology, Plön, Germany
| | - Ronan Ledevin
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, CNRS, University Lyon 1, Campus de la Doua, Villeurbanne, France
| | - Sophie Pantalacci
- ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratoire de Biologie et Modélisation de la Cellule, 15 parvis Descartes, F-69007, UnivLyon, Lyon, France
| | - Leslie M Turner
- Department of Evolutionary Genetics, Max-Planck Institute for Evolutionary Biology, Plön, Germany.,Department of Biology and Biochemistry, Milner Centre for Evolution, University of Bath, Bath, Unites States
| | - Eirikur Steingrimsson
- Department of Biochemistry and Molecular Biology, BioMedical Center, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Sabrina Renaud
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, CNRS, University Lyon 1, Campus de la Doua, Villeurbanne, France
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Irish JD, Hemphill BE, de Ruiter DJ, Berger LR. The apportionment of tooth size and its implications in
Australopithecus sediba
versus other Plio‐pleistocene and recent African hominins. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 161:398-413. [DOI: 10.1002/ajpa.23039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 06/08/2016] [Accepted: 06/09/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Joel D. Irish
- Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and PsychologyLiverpool John Moores UniversityLiverpoolL3 3AF UK
- Evolutionary Studies Institute and Centre for Excellence in PaleoSciencesUniversity of the WitwatersrandPrivate Bag 3, WITS 2050Johannesburg South Africa
| | | | - Darryl J. de Ruiter
- Department of AnthropologyTexas A&M UniversityCollege Station TX77843
- Evolutionary Studies Institute and Centre for Excellence in PaleoSciencesUniversity of the WitwatersrandPrivate Bag 3, WITS 2050Johannesburg South Africa
| | - Lee R. Berger
- Evolutionary Studies Institute and Centre for Excellence in PaleoSciencesUniversity of the WitwatersrandPrivate Bag 3, WITS 2050Johannesburg South Africa
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Polychronis G, Halazonetis DJ. Shape covariation between the craniofacial complex and first molars in humans. J Anat 2014; 225:220-31. [PMID: 24916927 PMCID: PMC4111929 DOI: 10.1111/joa.12202] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2014] [Indexed: 12/31/2022] Open
Abstract
The occurrence of mutual genetic loci in morphogenesis of the face and teeth implies shape covariation between these structures. However, teeth finalize their shape at an early age, whereas the face grows and is subjected to environmental influences for a prolonged period; it is therefore conceivable that covariation might modulate with age. Here we investigate the extent of this covariation in humans by measuring the 3D shape of the occlusal surface of the permanent first molars and the shape of the craniofacial complex from lateral radiographs, at two maturations stages. A sample of Greek subjects was divided into two groups (110 adult, 110 prepubertal) with equally distributed gender. The occlusal surfaces of the right first molars were 3D scanned from dental casts; 265 and 274 landmarks (including surface and curve semilandmarks) were digitized on the maxillary and mandibular molars, respectively. The corresponding lateral cephalometric radiographs were digitized with 71 landmarks. Geometric morphometric methods were used to assess shape variation and covariation. The vertical dimension of the craniofacial complex was the main parameter of shape variation, followed by anteroposterior deviations. The male craniofacial complex was larger (4.0-5.7%) and was characterized by a prominent chin and clockwise rotation of the cranial base (adult group only). Allometry was weak and statistically significant only when examined for the sample as a whole (percent variance explained: 2.1%, P = 0.0002). Covariation was statistically significant only between the lower first molar and the craniofacial complex (RV = 14.05%, P = 0.0099, and RV = 12.31%, P = 0.0162, for the prepubertal and adult groups, respectively). Subtle age-related covariation differences were noted, indicating that environmental factors may influence the pattern and strength of covariation. However, the main pattern was similar in both groups: a class III skeletal pattern (relative maxillary retrusion and mandibular protrusion), hyperdivergency, forward rotation of the posterior cranial base and upward rotation of the anterior cranial base were associated with mesiodistal elongation of the lower molars and height reduction of their distal cusps. This pattern mimics phylogeny in humans, where flexion and counterclockwise rotation of the cranial base, considered advantageous to survival, co-occur with tooth reductions that cannot be easily explained in evolutionary terms. The similarity of the phylogenetic and covariation patterns seems to support the pleiotropic gene hypothesis.
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Affiliation(s)
- Georgios Polychronis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
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Labonne G, Navarro N, Laffont R, Chateau-Smith C, Montuire S. Developmental integration in a functional unit: deciphering processes from adult dental morphology. Evol Dev 2014; 16:224-32. [DOI: 10.1111/ede.12085] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Gaëlle Labonne
- Laboratoire PALEVO; Ecole Pratique des Hautes Etudes; 6 bd Gabriel Dijon France
- UMR uB/CNRS 6282-Biogéosciences; Université de Bourgogne; 6 bd Gabriel Dijon France
| | - Nicolas Navarro
- Laboratoire PALEVO; Ecole Pratique des Hautes Etudes; 6 bd Gabriel Dijon France
- UMR uB/CNRS 6282-Biogéosciences; Université de Bourgogne; 6 bd Gabriel Dijon France
| | - Rémi Laffont
- UMR uB/CNRS 6282-Biogéosciences; Université de Bourgogne; 6 bd Gabriel Dijon France
| | | | - Sophie Montuire
- Laboratoire PALEVO; Ecole Pratique des Hautes Etudes; 6 bd Gabriel Dijon France
- UMR uB/CNRS 6282-Biogéosciences; Université de Bourgogne; 6 bd Gabriel Dijon France
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Polychronis G, Christou P, Mavragani M, Halazonetis DJ. Geometric morphometric 3D shape analysis and covariation of human mandibular and maxillary first molars. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 152:186-96. [PMID: 24009105 DOI: 10.1002/ajpa.22340] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 06/20/2013] [Accepted: 06/20/2013] [Indexed: 12/31/2022]
Abstract
Dental casts of 160 Greek subjects (80 males, 80 females) were scanned by a structured-light scanner. The upper and lower right first molar occlusal surface 3D meshes were processed using geometric morphometric methods. A total of 265 and 274 curve and surface sliding semilandmarks were placed on the upper and lower molar surfaces, respectively. Principal component analysis and partial least square analysis were performed to assess shape parameters. Molars tended to vary between an elongated and a more square form. The first two principal components (PCs), comprising almost 1/3 of molar shape variation, were related to mesiodistal-buccolingual ratios and relative cusp position. Distal cusps displayed the greatest shape variability. Molars of males were larger than those of females (2.8 and 3.2% for upper and lower molars respectively), but no shape dimorphism was observed. Upper and lower molar sizes were significantly correlated (r(2) = 0.689). Allometry was observed for both teeth. Larger lower molars were associated with shorter cusps, expansion of the distal cusp, and constriction of the mesial cusps (predicted variance 3.25%). Upper molars displayed weaker allometry (predicted variance 1.59%). Upper and lower molar shape covariation proved significant (RV = 17.26%, P < 0.0001). The main parameter of molar covariation in partial least square axis 1, contributing to 30% of total covariation, was cusp height, in contrast to the primary variability traits exhibited by PC1 and PC2. The aim of this study was to evaluate shape variation and covariation, including allometry and sexual dimorphism, of maxillary and mandibular first permanent molar occlusal surfaces.
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Affiliation(s)
- Georgios Polychronis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, 11527, Greece
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Shimizu T, Ogawa N, Hiraki A, Maeda T. Analysis of the genetic association between face breadth and maxillary arch width using SMXA recombinant inbred mouse strains. PEDIATRIC DENTAL JOURNAL 2013. [DOI: 10.1016/j.pdj.2013.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Komatsu T, Kurihara T, Ito Y, Lee MCI, Miyagi A, Ikeda M. Oral characteristics of a patient with Ekman-Westborg-Julin trait: a case history. SPECIAL CARE IN DENTISTRY 2012; 32:70-4. [PMID: 22416990 DOI: 10.1111/j.1754-4505.2012.00238.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article presents the case of a Japanese woman who had Ekman-Westborg-Julin trait. She had general macrodontia with multituberculism, evagination of the premolar, single conical roots, shovel-shaped incisors, enamel hypoplasia, impacted tooth, dental crowding, and an open bite. The oral and general characteristics of this patient are described and include the histological and radiographic findings of the mandibular third molars. We suggest that the distinctive oral features with macrodontia of the permanent teeth, multituberculism, evagination, single conical roots, and impaction of the tooth could be defined as the Ekman-Westborg-Julin trait.
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Affiliation(s)
- Tomoko Komatsu
- Department of Clinical Care Medicine, Division of Dentistry for Special Patients, Kanagawa Dental College, Kanagawa, Japan.
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Gómez-Robles A, Polly PD. MORPHOLOGICAL INTEGRATION IN THE HOMININ DENTITION: EVOLUTIONARY, DEVELOPMENTAL, AND FUNCTIONAL FACTORS. Evolution 2012; 66:1024-43. [DOI: 10.1111/j.1558-5646.2011.01508.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Renaud S, Pantalacci S, Auffray JC. Differential evolvability along lines of least resistance of upper and lower molars in island house mice. PLoS One 2011; 6:e18951. [PMID: 21589657 PMCID: PMC3092747 DOI: 10.1371/journal.pone.0018951] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 03/15/2011] [Indexed: 11/30/2022] Open
Abstract
Variation within a population is a key feature in evolution, because it can increase or impede response to selection, depending on whether or not the intrapopulational variance is correlated to the change under selection. Hence, main directions of genetic variance have been proposed to constitute “lines of least resistance to evolution” along which evolution would be facilitated. Yet, the screening of selection occurs at the phenotypic level, and the phenotypic variance is not only the product of the underlying genetic variance, but also of developmental processes. It is thus a key issue for interpreting short and long term evolutionary patterns to identify whether main directions of phenotypic variance indeed constitute direction of facilitated evolution, and whether this is favored by developmental processes preferably generating certain phenotypes. We tackled these questions by a morphometric quantification of the directions of variance, compared to the direction of evolution of the first upper and lower molars of wild continental and insular house mice. The main phenotypic variance indeed appeared as channeling evolution between populations. The upper molar emerged as highly evolvable, because a strong allometric component contributed to its variance. This allometric relationship drove a repeated but independent evolution of a peculiar upper molar shape whenever size increased. This repeated evolution, together with knowledge about the molar development, suggest that the main direction of phenotypic variance correspond here to a “line of least developmental resistance” along which evolution between population is channeled.
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Affiliation(s)
- Sabrina Renaud
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, Villeurbanne, France.
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Quantitative trait locus analysis of gutter-shaped root(s) in C57L/J mouse. PEDIATRIC DENTAL JOURNAL 2010. [DOI: 10.1016/s0917-2394(10)70194-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Renaud S, Pantalacci S, Quéré JP, Laudet V, Auffray JC. Developmental constraints revealed by co-variation within and among molar rows in two murine rodents. Evol Dev 2009; 11:590-602. [PMID: 19754715 DOI: 10.1111/j.1525-142x.2009.00365.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Morphological integration corresponds to interdependency between characters that can arise from several causes. Proximal causes of integration include that different phenotypic features may share common genetic sets and/or interact during their development. Ultimate causes may be the prolonged effect of selection favoring integration of functionally interacting characters, achieved by the molding of these proximal causes. Strong and direct interactions among successive teeth of a molar row are predicted by genetic and developmental evidences. Functional constraints related to occlusion, however, should have selected more strongly for a morphological integration of occluding teeth and a corresponding evolution of the underlying developmental and genetic pathways. To investigate how these predictions match the patterns of phenotypic integration, we studied the co-variation among the six molars of the murine molar row, focusing on two populations of house mice (Mus musculus domesticus) and wood mice (Apodemus sylvaticus). The size and shape of the three upper and lower molars were quantified and compared. Our results evidenced similar patterns in both species, size being more integrated than shape among all the teeth, and both size and shape co-varying strongly between adjacent teeth, but also between occluding teeth. Strong co-variation within each molar row is in agreement with developmental models showing a cascade influence of the first molar on the subsequent molars. In contrast, the strong co-variation between molars of the occluding tooth rows confirms that functional constraints molded patterns of integration and probably the underlying developmental pathways despite the low level of direct developmental interactions occurring among molar rows. These patterns of co-variation are furthermore conserved between the house mouse and the wood mouse that diverged >10 Ma, suggesting that they may constitute long-running constraints to the diversification of the murine rodent dentition.
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Affiliation(s)
- Sabrina Renaud
- Paléoenvironnements et Paléobiosphère, UMR 5125, CNRS, Université Lyon 1, 69622 Villeurbanne, France.
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Burgio G, Baylac M, Heyer E, Montagutelli X. Genetic analysis of skull shape variation and morphological integration in the mouse using interspecific recombinant congenic strains between C57BL/6 and mice of the mus spretus species. Evolution 2009; 63:2668-86. [PMID: 19490077 DOI: 10.1111/j.1558-5646.2009.00737.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To assess the genetic basis of the skull shape variation and morphological integration in mice, we have used a tool based on the cross between the distantly related mouse species Mus spretus (SEG/Pas strain) and the laboratory strain C57BL/6 called interspecific recombinant congenic strains (IRCSs). The genome of each IRCS consists on average of 1.3% of SEG/Pas derived sequences, located on multiple chromosomes as small-sized, DNA segments. Quantitative trait loci (QTL) on the skull shape, separated into dorsal and ventral sides, were analyzed in 17 IRCSs by a Procrustes superimposition method using 3D landmarks. The shapes of 16 strains differed significantly from C57BL/6. Discrepancy in the QTLs effects was found between the dorsal side and the anterior region of the ventral side due to a differential effect of the SEG/Pas alleles on the skull shape. A comprehensive analysis of all allelic combinations of the BCG-66H strain showed strong epistatic interactions between SEG/Pas segment acting on both skull sides. Epistatic pleiotropy and covariation between sides were dependent in SEG/Pas alleles direction and contributed to the strong morphological integration between sides. Introduction of Mus spretus alleles in a C57BL/6 background induced strong morphological changes mostly in SEG/Pas alleles direction and provided evidence for high level of morphological integration.
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Affiliation(s)
- Gaëtan Burgio
- Unité postulante de Génétique fonctionnelle de la Souris, CNRS URA 2578, Institut Pasteur, 75724 Paris cedex 15, France.
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Charles C, Pantalacci S, Peterkova R, Tafforeau P, Laudet V, Viriot L. Effect of eda loss of function on upper jugal tooth morphology. Anat Rec (Hoboken) 2009; 292:299-308. [PMID: 19051250 DOI: 10.1002/ar.20804] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The Tabby/eda mice, which bear a loss of function mutation for the eda (ectodysplasinA) gene, are known to display developmental anomalies in organs with an ectodermal origin. Although the lower jugal (cheek) teeth of Tabby/eda mice have been extensively studied, upper teeth have never been investigated in detail. However, this may help us to further understand the function of the eda gene in tooth development. In this work, the shape and size of both the crown and the radicular system were studied in the Tabby/eda mice upper jugal teeth. To deal with the high morphological variability, we defined several morphotypes based on cusp numbers and position. Statistical tests were then performed within and between the different morphotypes to test the correlation between tooth size and morphology. Our analysis reveals that, as in lower teeth, eda is necessary to segment the dental lamina into three teeth with the characteristic size and proportions of the mouse. Nevertheless, since strong effects are observed in heterozygous upper teeth while lower are only mildly affected, it seems that the upper jaw is more sensitive than the lower jaw to the loss of eda function. Modifications in cusp number and the abnormal crown size of the teeth are clearly linked, and our results indicate a role of eda in cusp patterning. Moreover, we found that the Tabby mutation induces variations in the dental root pattern, sometimes associated with hypercementosis, suggesting a newly uncovered role played by eda in root patterning and formation.
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Affiliation(s)
- Cyril Charles
- iPHEP, CNRS UMR 6046, Faculté SFA, Université de Poitiers, 40 avenue du recteur Pineau, Poitiers Cedex, France.
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Keller JM, Huet-Hudson YM, Leamy LJ. Qualitative effects of dioxin on molars vary among inbred mouse strains. Arch Oral Biol 2006; 52:450-4. [PMID: 17141729 PMCID: PMC1916485 DOI: 10.1016/j.archoralbio.2006.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Revised: 10/16/2006] [Accepted: 10/21/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE We evaluated the effects of different levels of the potent environmental toxicant and teratogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), on molar development in mice in six inbred strains, all with TCDD responsive Ahr alleles. DESIGN Pregnant females were exposed on gestation day 13 to 4 different levels of TCDD (control, 0.01, 0.1 and 1.0 microg/kg) and their offspring were examined for the frequency of missing third molars (M3s) and for differences in first mandibular molar (M1) cuspal morphology. RESULTS Missing M3s were prevalent only in mice in two strains, C3H/HeJ and CBA/J, and their frequency significantly increased with increasing TCDD exposure. The frequency of the M1 variant was high in mice in only one strain, C57BL/10J, and was significantly higher in the treated compared with the control group. CONCLUSIONS Inbred mice strains exhibited differential responses to TCDD suggesting that there is a genetic component, beyond Ahr differences, mediating the effects of TCDD on molar development.
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MESH Headings
- Alleles
- Animals
- Anodontia/chemically induced
- Basic Helix-Loop-Helix Transcription Factors
- Environmental Exposure
- Environmental Pollutants/toxicity
- Female
- Gestational Age
- Male
- Mice
- Mice, Inbred A
- Mice, Inbred BALB C
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Mice, Inbred Strains
- Molar/abnormalities
- Molar/drug effects
- Molar, Third/abnormalities
- Molar, Third/drug effects
- Odontogenesis/drug effects
- Polychlorinated Dibenzodioxins/toxicity
- Pregnancy
- Prenatal Exposure Delayed Effects
- Receptors, Aryl Hydrocarbon/drug effects
- Receptors, Aryl Hydrocarbon/genetics
- Teratogens/toxicity
- Tooth Crown/abnormalities
- Tooth Crown/drug effects
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Affiliation(s)
- J M Keller
- Department of Biology, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001, USA.
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