Experimental Production of Shell Abnormalities in Turtles

Lynn, W. Gardner; Ullrich, Coralie

doi:10.2307/1437903

Cited by 61 publications

(47 citation statements)

References 7 publications

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“…COKER (1910) was the first author to question that these anomalies are a result of mutations in the embryogenesis, an idea that later on was supported by other investigators (LYNN 1937, LYNN & ULLRICH 1950, FRYE 1991.…”

mentioning

confidence: 96%

Supernumerary epidermal shields and carapace variation in Orbigny's slider turtles, Trachemys dorbigni (Testudines, Emydidae)

Bujes

Verrastro

2007

Rev. Bras. Zool.

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The epidermal plates of the carapace and plastron of 51 adults (38 females and 13 males), 07 immature individuals, and 46 hatchlings of the freshwater turtle Trachemys dorbigni (Durémil & Bibron, 1835), originated from the delta of Rio Jacuí region, Rio Grande do Sul state, Brazil, were examined. The results showed that 7.7% of males, 10.52% of females, 14.28% of immature individuals, and 6.52% of the hatchlings presented a kind of anomaly on the shell, as well as a presence of supernumerary epidermal shields. Although the modification in the number of epidermal shields presents a high frequency in Testudines, these are the first descriptions of the variation in the pattern of carapacial scutation in eleven individuals from a population of T. dorbigni. The association of several environmental factors acting on the embryonic development of the individual may be responsible for the alteration of the pattern of carapacial scutation in this species.

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mentioning

confidence: 96%

Supernumerary epidermal shields and carapace variation in Orbigny's slider turtles, Trachemys dorbigni (Testudines, Emydidae)

Bujes

Verrastro

2007

Rev. Bras. Zool.

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“…alguns experimentos realizados em laboratório apontam que fatores como temperatura, umidade, potencial hídrico, e tensões gasosas dentro do ninho, podem implicar na mortalidade e surgimento de anomalias nos embriões de répteis (lynn & ullrich, 1950;Packard et al 1987;Packard & Packard, 1988). o ambiente hídrico e termal dos ninhos dos quelônios pode ser influenciado por vários fatores ambientais e ecológicos, dentre eles a profundidade do ninho (Burger, 1976;Wilhoft et al, 1983), posicionamento do ninho e cobertura vegetal (vogt & Bull, 1984) e data da desova (Mrosovsky et al, 1984).…”

Section: Discussionunclassified

“…neste sentido, é possível construir a hipótese de que, provavelmente, as espécies de quelônios que possuem ovos de casca flexível geram uma maior proporção de filhotes com defeitos do que as espécies com ovos de casca rígida. a ocorrência de adição e/ou supressão de escudos no casco, apresentam-se, provavelmente, como não letais, uma vez que exemplares adultos têm sido encontrados na natureza com tais defeitos (Cagle, 1950;lynn & ullrich, 1950;Molina, 1995). Mas, como ressaltam Mast & Carr (1989), os padrões anormais no casco representam expressões fenotípicas de algum problema morfológico ou fisiológico, ainda não manifesto, que pode afetar a viabilidade do indivíduo.…”

Section: Discussionunclassified

Avaliação de padrão irregular dos escudos do casco em Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae)

2009

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RESUMOo casco de Podocnemis expansa (tartaruga-da-amazônia) e Podocnemis unifilis (tracajá), os maiores quelônios de água doce da américa do Sul, é uma estrutura única que diferencia esse grupo dos vertebrados atuais e está associado a alguns padrões comportamentais. o padrão dos escudos que compõem o casco dos quelônios é bastante uniforme, mas variações já foram descritas e analisadas para um grande número de espécies em todas as famílias existentes atualmente. averiguou-se a incidência de irregularidades do padrão de escutelação no casco dessas espécies, durante os anos de 1999 a 2003 no rio Javaés, entorno do Parque nacional do araguaia e da Área de Proteção ambiental Bananal/ Cantão, oeste do estado do Tocantins. P. expansa se apresenta como uma espécie mais suscetível à ocorrência de anormalidades no casco em relação a P. unifilis. Sendo que, dos 14.378 filhotes avaliados, (13,32 %) apresentavam irregularidades no padrão de escutelação enquanto que dos 1.329 filhotes de P. unifilis apenas (4,44 %). em P. expansa, os defeitos ocorreram quase que em sua totalidade na carapaça (98,64 %) e em menor número (83,05 %) em P. unifilis. PALAVRAS-CHAVE:Podocnemis expansa, Podocnemis unifilis, anormalidade, casco, rio Javaés. Evaluation of irregular pattern of the shell scutes in Podocnemis expansa and Podocnemis unifilis (Testudines, Podocnemididae) ABSTRACTThe shell of Podocnemis expansa (amazonian giant river turtle) and Podocnemis unifilis (Yellow-spotted amazon river Turtle), the largest South american turtles, is a unique structure that differentiates them from other known vertebrates; and it is associated with some of their behavioral patterns. Their scute pattern is quite uniform however variations have been described and analyzed for a great number of other species of existing families. in the Javaés river, from 1999 to 2003, we observed an occurrence of abnormalities in their scute pattern. This was in the vicinity of the araguaia national Park and the Bananal/ Cantão environment Protected area, west of Tocantins state. of the both species, P. expansa is more susceptible to shell abnormalities. of 14.378 P. expansa hatchlings observed, 13.32 % presented scute pattern abnormalities, while of 1.329 P. unifilis hatchlings, only 4.44 %. The incidence of abnormalities occurred only in the carapace, namely, 98.64% in P. expansa, and 83.05% in P. unifilis.

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“…Lynn and Ullrich [1950] found that eggs of the eastern painted turtle ( C. picta picta ) and the snapping turtle exposed to changes in moisture conditions during certain developmental stages often gave rise to offspring presenting various types of congenital abnormalities, such as asymmetric carapace, abnormal scutellation, jaw anomalies, and eyeless and mouthless stump. More recently, Zimm et al [2017] reported a synergistic effect of high temperatures and dry conditions in the development of abnormal scutellation patterns in turtles.…”

Section: Hox Genes Teratogenesis and Environmental Influencementioning

confidence: 99%

<b><i>Hox</i></b> Genes in Reptile Development, Epigenetic Regulation, and Teratogenesis

Martín-del-Campo

Sifuentes-Romero

García‐Gasca

2018

Cytogenet Genome Res

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Reptiles are ancestral organisms presenting a variety of shapes, from the elongated vertebral column of the snake to the turtle dorsalized ribs or retractile neck. Body plans are specified by a conserved group of homeobox-containing genes (Hox genes), which encode transcription factors important in cell fate and vertebral architecture along the anteroposterior axis during embryonic development; thus, dysregulation of these genes may cause congenital malformations, from mild-sublethal to embryonic-lethal. The genetic pool, maternal transfer, and environmental conditions during egg incubation affect development; environmental factors such as temperature, moisture, oxygen, and pollution may alter gene expression by epigenetic mechanisms. Thus, in this review, we present information regarding Hox genes and development in reptiles, including sex determination and teratogenesis. We also present some evidence of epigenetic regulation of Hox genes and the role of the environment in epigenetic modulation of gene expression. So far, the evidence suggests that the molecular instructions encoded by Hox genes to build a snake, a lizard, or a turtle represent the interplay between genome and epigenome after years of evolution, with occasional environmentally induced molecular mistakes leading to abnormal body shapes.

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Experimental Production of Shell Abnormalities in Turtles

Cited by 61 publications

References 7 publications

Supernumerary epidermal shields and carapace variation in Orbigny's slider turtles, Trachemys dorbigni (Testudines, Emydidae)

Supernumerary epidermal shields and carapace variation in Orbigny's slider turtles, Trachemys dorbigni (Testudines, Emydidae)

Avaliação de padrão irregular dos escudos do casco em Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae)

<b><i>Hox</i></b> Genes in Reptile Development, Epigenetic Regulation, and Teratogenesis

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