Molecular decay of enamel matrix protein genes in turtles and other edentulous amniotes

Meredith, Robert W.; Gatesy, John; Springer, Mark S.

doi:10.1186/1471-2148-13-20

Cited by 56 publications

(66 citation statements)

References 59 publications

(97 reference statements)

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“…The Khoesan are the most ancient ancestral peoples of southern Africa, as reflected in their distinctive genome (Schlebusch et al, 2013). The Black Africans of South Africa, often referred to as Bantu, are genetically distinctive from the West Africans that dominate the gene pool of African‐Americans (Tishkoff et al, 2009; Silva et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

Cortical bone histomorphology of known‐age skeletons from the Kirsten collection, Stellenbosch university, South Africa

Pfeiffer

Heinrich

Beresheim

et al. 2016

American J Phys Anthropol

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ObjectivesNormal human bone tissue changes predictably as adults get older, but substantial variability in pattern and pace remains unexplained. Information is needed regarding the characteristics of histological variables across diverse human populations.MethodsUndecalcified thin sections from mid‐thoracic ribs of 213 skeletons (138 M, 75 F, 17–82 years, mean age 48 years), are used to explore the efficacy of an established age‐at‐death estimation method and methodological approach (Cho et al.: J Forensic Sci 47 (2002) 12‐18) and expand on it. The ribs are an age‐balanced sample taken from skeletonized cadavers collected from 1967 to 1999 in South Africa, each with recorded sex, age, cause of death and government‐defined population group (129 “Colored,” 49 “Black,” 35 “White”).ResultsThe Ethnicity Unknown equation performs better than those developed for European‐Americans and African‐Americans, in terms of accuracy and bias. A new equation based solely on the study sample does not improve accuracy. Osteon population densities (OPD) show predicted values, yet secondary osteon areas (On.Ar) are smaller than expected for non‐Black subgroups. Relative cortical area (Ct.Ar/Tt.Ar) is low among non‐Whites.ConclusionsResults from this highly diverse sample show that population‐specific equations do not increase estimate precision. While within the published range of error for the method (±24.44 years), results demonstrate a systematic under‐aging of young adults and over‐aging of older adults. The regression approach is inappropriate. The field needs fresh approaches to statistical treatment and to factors behind cortical bone remodeling. Am J Phys Anthropol 160:137–147, 2016. © 2016 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc.

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Section: Methodsmentioning

confidence: 99%

Cortical bone histomorphology of known‐age skeletons from the Kirsten collection, Stellenbosch university, South Africa

Pfeiffer

Heinrich

Beresheim

et al. 2016

American J Phys Anthropol

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“…1) (13). The antiquity of tooth loss in turtles may therefore have provided an extended window for tooth gene degradation in this clade (13). Among enamelless mammals with genome sequences (sloth, armadillo, and aardvark), the DSPP gene remains intact, whereas MMP20, ENAM, AMTN, AMELX, and AMBN genes have been inactivated, with the exception of AMBN and MMP20 in armadillo (Fig.…”

Section: A Flock Of Genomesmentioning

confidence: 99%

“…However, the synteny of these six tooth-related genes is strongly conserved across species. The only exceptions occur in Meleagris gallopavo (turkey), where ENAM exon 9 is found on both chromosome 1 and Z (13), and in the Pterocles guturalis (sandgrouse), where there appear to be multiple copies of exon 5 (four copies), exon 6 (three copies), and exon 10 (two copies) of MMP20 scattered across five contigs ( fig. S7).…”

Section: Parallel Tooth and Enamel Lossmentioning

confidence: 99%

“…The inactivation of enamel-related genes parallels the loss of enamel in the mammalian fossil record (4,(11)(12)(13). The presence of shared, inactivating mutations in dentin-and enamel-related genes could therefore be used as a molecular proxy to assess whether teeth were lost once or on multiple occasions in the common ancestor of living birds, as well as to estimate the timing of tooth loss.…”

Section: Parallel Tooth and Enamel Lossmentioning

confidence: 99%

“…Of the hundreds of genes associated with tooth development, most are pleiotropic and perform essential functions outside of tooth development (15). By contrast, the aforementioned six genes have been hypothesized to be tooth-specific based on mutagenesis studies in mice, inactivation of these genes in one or more edentulous/enamelless vertebrate species, and natural genetic variation in humans that causes nonsyndromic amelogenesis imperfecta, dentinogenesis imperfecta, and dentin dysplasia (11)(12)(13)(16)(17)(18)(19)(20) (table S1). At the same time, other evidence indicates that these six genes are pleiotropic and are expressed outside of tooth development (21)(22)(23) (table S1).…”

Section: Parallel Tooth and Enamel Lossmentioning

confidence: 99%

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Evidence for a single loss of mineralized teeth in the common avian ancestor

Meredith

Zhang

Gilbert

et al. 2014

Science

103

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Edentulism, the absence of teeth, has evolved convergently among vertebrates, including birds, turtles, and several lineages of mammals. Instead of teeth, modern birds (Neornithes) use a horny beak (rhamphotheca) and a muscular gizzard to acquire and process food. We performed comparative genomic analyses representing lineages of nearly all extant bird orders and recovered shared, inactivating mutations within genes expressed in both the enamel and dentin of teeth of other vertebrate species, indicating that the common ancestor of modern birds lacked mineralized teeth. We estimate that tooth loss, or at least the loss of enamel caps that provide the outer layer of mineralized teeth, occurred about 116 million years ago.

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Prenatal Development of the Humpback Whale: Growth Rate, Tooth Loss and Skull Shape Changes in an Evolutionary Framework

Lanzetti

Berta

Ekdale

2018

The Anatomical Record

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Extant baleen whales (Mysticeti) share a distinct suite of extreme and unique adaptations to perform bulk filter feeding, such as a long, arched skull, and mandible and the complete loss of adult dentition in favor of baleen plates. However, mysticetes still develop tooth germs during ontogeny. In the fossil record, multiple groups document the transition from ancestral raptorial feeding to filter feeding. Fetal specimens give us an extraordinary opportunity to observe when and how this macroevolutionary transition occurs during gestation. We used iodine-enhanced and traditional CT scanning to visualize the internal anatomy of five fetuses of humpback whale representing the first two-thirds of gestation, and we combine these data with previously published reports to provide the first comprehensive qualitative description of the sequence of developmental changes that characterize the skull and dentition. We also use quantitative methods based on 3D landmarks to investigate the shape changes in the fetuses in relation to a juvenile cranial morphology. We found similarities in the ossification patterns of the humpback and other cetaceans (dolphins), but there appear to be major differences when comparing them to terrestrial artiodactyls. As for the tooth germs, this developmental sequence confirms that the tooth-tobaleen transition occurs in the last one-third of gestation. Analysis of cranial shape development revealed a progressive elongation of the rostrum and a resulting posterior movement of the nasals relative to the braincase. Future work will involve acquisition of data from other species to complete our documentation of the teeth-to-baleen transition.

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Molecular decay of enamel matrix protein genes in turtles and other edentulous amniotes

Cited by 56 publications

References 59 publications

Cortical bone histomorphology of known‐age skeletons from the Kirsten collection, Stellenbosch university, South Africa

Cortical bone histomorphology of known‐age skeletons from the Kirsten collection, Stellenbosch university, South Africa

Evidence for a single loss of mineralized teeth in the common avian ancestor

Prenatal Development of the Humpback Whale: Growth Rate, Tooth Loss and Skull Shape Changes in an Evolutionary Framework

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