First approximation to congenital malformation rates in embryos and hatchlings of sea turtles

Bárcenas-Ibarra, Annelisse; Cueva, Horacio de la; Rojas‐Lleonart, Isaias; Abreu-Grobois, F. Alberto; Lozano‐Guzmán, Rogelio Iván; Cuevas, Eduardo; García‐Gasca, Alejandra

doi:10.1002/bdra.23342

Cited by 30 publications

(65 citation statements)

References 81 publications

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“…Developmental anomalies are associated with extreme temperatures in freshwater turtle and mammalian embryos (Edwards ; Packard & Packard ), but although studies are limited in number, no strong association has been demonstrated for marine turtles (Bárcenas‐Ibarra et al . ). Hewavisenthi and Parmenter (2001) showed a significant influence of temperature on carapace scute anomalies in the flatback turtle ( Natator depressus ); however, these observations were detected at the lower end of the thermal tolerance limits.…”

Section: Discussionmentioning

confidence: 97%

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Loggerhead sea turtle embryos (Caretta caretta) regulate expression of stress response and developmental genes when exposed to a biologically realistic heat stress

et al. 2017

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Oviparous reptile embryos are expected to breach their critical thermal maxima if temperatures reach those predicted under current climate change models due to the lack of the maternal buffering processes and parental care. Heat-shock proteins (HSPs) are integral in the molecular response to thermal stress, and their expression is heritable, but the roles of other candidate families such as the heat-shock factors (HSFs) have not been determined in reptiles. Here, we subject embryonic sea turtles (Caretta caretta) to a biologically realistic thermal stress and employ de novo transcriptomic profiling of brain tissue to investigate the underlying molecular response. From a reference transcriptome of 302 293 transcripts, 179 were identified as differentially expressed between treatments. As anticipated, genes enriched in the heat-shock treatment were primarily associated with the Hsp families, or were genes whose products play similar protein editing and chaperone functions (e.g. bag3, MYOC and serpinh1). Unexpectedly, genes encoding the HSFs were not significantly upregulated under thermal stress, indicating their presence in unstressed cells in an inactive state. Genes that were downregulated under thermal stress were less well functionally defined but were associated with stress response, development and cellular organization, suggesting that developmental processes may be compromised at realistically high temperatures. These results confirm that genes from the Hsp families play vital roles in the thermal tolerance of developing reptile embryos and, in addition with a number of other genes, should be targets for evaluating the capacity of oviparous reptiles to respond adaptively to the effects of climate change.

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Section: Discussionmentioning

confidence: 97%

“…Despite this limited available data, high temperatures are still hypothesized to promote the occurrence of congenital malformations (Bárcenas‐Ibarra et al . ). We show that the gene tgm3 , which encodes for a protein associated with epidermis development in mammalian embryogenesis (Zhang et al .…”

Section: Discussionmentioning

confidence: 97%

Loggerhead sea turtle embryos (Caretta caretta) regulate expression of stress response and developmental genes when exposed to a biologically realistic heat stress

et al. 2017

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“…Cyclopia has also been reported in 1 olive ridley sea turtle ( Lepidochelys olivacea ) embryo from Sinaloa, Mexico. The embryo did not hatch, although other siblings within the same nest hatched normally [Bárcenas-Ibarra et al, 2015].…”

Section: Hox Genes Teratogenesis and Environmental Influencementioning

confidence: 98%

<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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“…25 The prevalence of congenital malformations in embryos and hatchlings of sea turtles ranges from 0.2% to 2%, with the highest rate occurring in the olive ridley. 5 A wide variety of isolated and multiple congenital malformations have been reported in this species, 5 but there were no reports of SRS until it was observed in embryos from a Mexican Pacific hatchery. Thus, the purpose of the present study was to characterize the morphology and determine the overall prevalence of schistosomus reflexus in olive ridley sea turtles in this specific nesting beach in which conservation programs have been running uninterruptedly for 39 years and to establish the potential impact of this syndrome in the population.…”

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confidence: 99%

“…1,32 The most important nesting areas for this species are located in the Eastern Pacific coast; 28,32 nesting sites in Mexico extend from the southernmost tip of the Baja California peninsula to the coastline of Chiapas state. 28 A variety congenital malformations have been previously reported in olive ridleys 5 but not schistosomus reflexus syndrome (SRS). SRS is a rare and lethal congenital malformation occurring primarily in ruminants, mostly cattle.…”

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confidence: 99%

Schistosomus Reflexus Syndrome in Olive Ridley Sea Turtles (Lepidochelys olivacea)

et al. 2016

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The olive ridley sea turtle ( Lepidochelys olivacea), considered the most abundant sea turtle species, is listed as vulnerable on the International Union for Conservation of Nature Red List. The most important nesting areas are located in the Eastern Pacific, and congenital malformations have been previously reported in this species. The present study was conducted in a single population at El Verde beach, one of the most important nesting beaches for the species in the northwestern Mexican Pacific. The study was based on embryos that had been incubated in a controlled environment. Schistosomus reflexus syndrome (SRS) was observed in 124 of 20 257 olive ridley embryos (0.6%), comprising 124 of 400 (31%) cases of congenital malformations over a 7-month period. Affected embryos had malformations of the carapace, bridge, or plastron, resulting in exposure of the abdominal or thoracic viscera, as well as spinal malformation and abnormal positioning of limbs adjacent to the head with subsequent ankylosis. SRS phenotypes (although lethal) varied from mild to severe, although most cases were severe. SRS was mostly associated with congenital malformations in the neck (short neck, 80%), tail (anury, 38%), and flippers (different types of dysmelias, 53%). In most cases of severe SRS, ankyloses were present. Documenting these findings could be important to identify the cause of the developmental defects, and identification of the cause of the defects may be of significance to the population and to our efforts to manage this and other populations at risk.

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First approximation to congenital malformation rates in embryos and hatchlings of sea turtles

Abstract: Olive ridleys seem more prone to the occurrence of congenital malformations than the other two species. Whether the observed malformation levels are normal or represent a health problem cannot be currently ascertained without long-term assessments.

Cited by 30 publications

References 81 publications

Loggerhead sea turtle embryos (Caretta caretta) regulate expression of stress response and developmental genes when exposed to a biologically realistic heat stress

Loggerhead sea turtle embryos (Caretta caretta) regulate expression of stress response and developmental genes when exposed to a biologically realistic heat stress

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

Schistosomus Reflexus Syndrome in Olive Ridley Sea Turtles (Lepidochelys olivacea)

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