Reptilian Tooth Regeneration

Richman, Joy M.; Whitlock, John A.; Abramyan, John

doi:10.1002/9781118498026.ch7

Cited by 7 publications

(2 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Organs are often replaced or renewed throughout the life of an organism as a feature of wild-type development. These programmed regenerative processes are especially common in epithelia and their associated organs, such as teeth ( Tucker and Fraser, 2014 ; Jernvall and Thesleff, 2012 ; Richman et al, 2013 ). Tooth replacement usually takes the form of whole-tooth regeneration, whereby entire new tooth organs differentiate while old teeth are removed by active shedding and/or dislodgement through use.…”

Section: Introductionmentioning

confidence: 99%

Modulation of tooth regeneration through opposing responses to Wnt and BMP signals in teleosts

Square,

Mackey,

Sundaram

et al. 2023

Development

View full text Add to dashboard Cite

Most vertebrate species undergo tooth replacement throughout adult life. This process is marked by the shedding of existing teeth and the regeneration of tooth organs. However, little is known about the genetic circuitry regulating tooth replacement. Here, we tested whether fish orthologs of genes known to regulate mammalian hair regeneration have effects on tooth replacement. Using two fish species that demonstrate distinct modes of tooth regeneration, threespine stickleback (Gasterosteus aculeatus) and zebrafish (Danio rerio), we found that transgenic overexpression of four different genes changed tooth replacement rates in the direction predicted by a hair regeneration model: Wnt10a and Grem2a increased tooth replacement rate, whereas Bmp6 and Dkk2 strongly inhibited tooth formation. Thus, similar to known roles in hair regeneration, Wnt and BMP signals promote and inhibit regeneration, respectively. Regulation of total tooth number was separable from regulation of replacement rates. RNA sequencing of stickleback dental tissue showed that Bmp6 overexpression resulted in an upregulation of Wnt inhibitors. Together, these data support a model in which different epithelial organs, such as teeth and hair, share genetic circuitry driving organ regeneration.

show abstract

Section: Introductionmentioning

confidence: 99%

Modulation of tooth regeneration through opposing responses to Wnt and BMP signals in teleosts

Square,

Mackey,

Sundaram

et al. 2023

Development

View full text Add to dashboard Cite

show abstract

“…Tooth replacement rate provides key information on the function and evolution of the dentition ( Edmund, 1960 ; Osborn, 1970 , 1975 ; Richman, Whitlock & Abramyan, 2013 ; Whitlock & Richman, 2013 ; Schwarz et al, 2015 ; LeBlanc et al, 2016 ; Bramble et al, 2017 ). Such data can be used to infer aspects of the paleobiology of extinct taxa including metabolic activity/investment, dietary preferences, and behavior ( Johnston, 1979 ; Barrett, 2014 ; Salakka, 2014 ; D’Emic et al, 2013 , 2019 ; D’Emic & Carrano, 2019 ; Brink et al, 2015 ; Button et al, 2017 ; D’Emic et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Sampling impacts the assessment of tooth growth and replacement rates in archosaurs: implications for paleontological studies

Kosch

Zanno

2020

PeerJ

View full text Add to dashboard Cite

Dietary habits in extinct species cannot be directly observed; thus, in the absence of extraordinary evidence, they must be reconstructed with a combination of morphological proxies. Such proxies often include information on dental organization and function such as tooth formation time and tooth replacement rate. In extinct organisms, tooth formation times and tooth replacement rate are calculated, in part via extrapolation of the space between incremental lines in dental tissues representing daily growth (von Ebner Line Increment Width; VEIW). However, to date, little work has been conducted testing assumptions about the primary data underpinning these calculations, specifically, the potential impact of differential sampling and data extrapolation protocols. To address this, we tested a variety of intradental, intramandibular, and ontogentic sampling effects on calculations of mean VEIW, tooth formation times, and replacement rates using histological sections and CT reconstructions of a growth series of three specimens of the extant archosaurian Alligator mississippiensis. We find transect position within the tooth and transect orientation with respect to von Ebner lines to have the greatest impact on calculations of mean VEIW—a maximum number of VEIW measurements should be made as near to the central axis (CA) as possible. Measuring in regions away from the central axis can reduce mean VEIW by up to 36%, causing inflated calculations of tooth formation time. We find little demonstrable impact to calculations of mean VEIW from the practice of subsampling along a transect, or from using mean VEIW derived from one portion of the dentition to extrapolate for other regions of the dentition. Subsampling along transects contributes only minor variations in mean VEIW (<12%) that are dwarfed by the standard deviation (SD). Moreover, variation in VEIW with distance from the pulp cavity likely reflects idiosyncratic patterns related to life history, which are difficult to control for; however, we recommend increasing the number of VEIW measured to minimize this effect. Our data reveal only a weak correlation between mean VEIW and body length, suggesting minimal ontogenetic impacts. Finally, we provide a relative SD of mean VEIW for Alligator of 29.94%, which can be used by researchers to create data-driven error bars for tooth formation times and replacement rates in fossil taxa with small sample sizes. We caution that small differences in mean VEIW calculations resulting from non-standardized sampling protocols, especially in a comparative context, will produce inflated error in tooth formation time estimations that intensify with crown height. The same holds true for applications of our relative SD to calculations of tooth formation time in extinct taxa, which produce highly variable maximum and minimum estimates in large-toothed taxa (e.g., 718–1,331 days in Tyrannosaurus).

show abstract

Resilience of the replacing dentition in adult reptiles

Henriquez,

Richman

2024

Developmental Biology

View full text Add to dashboard Cite

Reptilian Tooth Regeneration

Cited by 7 publications

References 67 publications

Modulation of tooth regeneration through opposing responses to Wnt and BMP signals in teleosts

Modulation of tooth regeneration through opposing responses to Wnt and BMP signals in teleosts

Sampling impacts the assessment of tooth growth and replacement rates in archosaurs: implications for paleontological studies

Resilience of the replacing dentition in adult reptiles

Contact Info

Product

Resources

About