Yahoo News, London, April 29 (ANI): Researchers working under the Joint International Turtle Genomes Consortium have completed the genome sequencing of soft-shell turtle (Pelodiscus sinensis) and green sea turtle (Chelonia mydas).
These achievements shed new light on the origin of turtles and applied the classical evo-devo model to explain the developmental process of their unique body plan.
The evolution of turtles is an enigma in science. Their distinct body design-with a sharp beak and protective hard shell has changed very little over the past 210 million years.
As the smallest species of soft-shell turtles, Chinese soft-shell turtle was once commonly sold in pet shops. Green sea turtle is considered as the largest of all the hard-shelled sea turtles and is named because of the green fat beneath its shell. Its population sizes have been drastically reduced recently and it has been listed as an endangered species.
To reveal the evolutionary history of turtles and the mechanisms underlying the development of their unique anatomical features, researchers in this project sequenced and analyzed the genomes of soft-shell turtle and green sea turtle.
The project, led by investigators from RIKEN, BGI, and Wellcome Trust Sanger Institute, found the evidence that turtles are likely to be a sister group with the common ancestor of crocodilians and birds from whole genome phylogenetic analyses.
The turtles were diverged from archosaurians approximately between 267.9 and 248.3 million years ago, which coincides with the time range of the Upper Permian to Triassic period that overlapped or followed shortly after the end of Permian extinction.
In the study, researchers performed the brief research on genes may be associated with the turtle-specific characteristics, and found some olfactory receptor (OR) gene families were highly expanded in both turtles.
This finding suggests that turtles have developed superior olfaction ability against a wide variety of hydrophilic substances. In addition, many genes involved in taste perception, hunger-stimulating, and energy homeostasis regulating hormone ghrelin have been uniquely lost in turtles. Researchers suggested that the loss of these genes might be related to their low-metabolic rate.
The consortium also investigated the association of embryonic gene expression profiles (GXP) and their morphological evolution pattern, based on ENSEMBL soft-shell turtle gene-set. By integrating RNA-seq technology, comparative genomics method, and mathematical statistical approaches, researchers confirmed GXP divergence during embryogenesis of soft-shell turtle and chicken indeed follows the developmental hourglass model. They also revealed that the maximal conservation stage occurred at around the vertebrate phylotypic period, rather than at later stage that show the amniote-common pattern.
To clarify the morphological specifications of turtle embryogenesis in late development, especially the formation of the carapacial ridge (CR), researchers investigated into CR-specific miRNA expression, found existence of tissue-specific miRNAs and involvement of Wnt signaling.
Also they revealed the Wnt expression involved in the carapacial ridge (CR) formation of the turtle shell, researchers annotated all the Wnt genes in the two turtle genomes, identifying a total of 20 Wnt genes. Intriguingly, they discovered Wnt5a is the only Wnt gene expressed in the turtle CR region, supporting the possible co-option of limb-associated Wnt signaling in the acquisition of this turtle-specific novelty. The findings were published online in Nature Genetics. (ANI)
Showing posts with label soft-shell turtle. Show all posts
Showing posts with label soft-shell turtle. Show all posts
Saturday, 11 May 2013
Saturday, 18 June 2011
Shelling out help for Kingdom's Turtles (Via Herp Digest)
Shelling out help for Kingdom's Turtles, Building US$20,000 Mekong Turtle Conservation Center for Cantor's Giant Soft-Shelled Turtle
6/10/11, by Kenneth Ingram and Phak Seangly, The Phnom Penh Post - Cambodia's Newspaper of Record:
Snapping at monks and government officials with jaws capable of shredding through bone, a rare adult Cantor's Giant Soft-Shelled turtle was one of 100 reptiles given a new home at a conservation centre that aims to boost dwindling turtle populations in Cambodia.
The US$20,000 Mekong Turtle Conservation Centre, constructed by NGO Conservation International within the confines of 100 Pillar pagoda in Kartie province's Sambro district, opened on Wednesday. It is intended as a sanctuary for four different types of turtles, including two endangered species, and contains facilities for raising baby turtles away from predators and researching the reptiles further.
Among the endangered reptiles are Cantor's Giant Soft-shelled turtles, with individuals known to weigh over 110 pounds and two meters in length. Featuring a distinct snout that earns it the name of 'frog head turtle' in Khmer, the breed inhabits the depths of freshwater streams and inland slow-moving river systems, feeding primarily on aquatic plants, fish, crab and shrimp.
The turtles - thought to be extinct in Vietnam and on the brink of extinction in Thailand and Laos - were virtually undetected in Cambodia until a biological survey, conducted in 2007, gained international attention for spotting them in a pristine natural habitat along the Mekong River. The discovery was an impetus for the new conservation centre.
"This centre will provide turtles with a safe environment to mature before they are introduced to the wild," project associate of Conservation International Sun Yoeung said, adding that baby turtles would be released once they reached between 10 months and two years old.
However, 15 four-day-old Cantor's turtles were released into the river yesterday, a Conservation International spokeswoman said, in part to facilitate the filming of a nature programme by French filmmakers.
"We don't want to take all of the hatchlings back to the centre because we don't know if they will all survive [there]," explained Som Sitha, monitoring and evaluation coordinator at Conservation International, pointing out that Cantor's turtles had never been raised in captivity before. "Also, we want to involve local fishermen and show them that we will release some turtles back into their habitat."
Sun Yoeung, 33, project associate of Conservation International, said human activity remained the greatest threat to turtle habitats.
"Turtle nests are easily found by people because of the large tracks that adults leave in the sand," he said. "People were eating the eggs, but this is less common now because of education about turtles."
Turtles are also sold to markets as ingredients for traditional Chinese medicines, ornaments and pets.
Environmentalists also attribute human activity to the destruction and pollution of turtle habitats through fishing, farming, small-scale mining near the Mekong River.
Community partnerships have been central to the success of the conservation effort thus far, said Sun Yoeung, as fishermen and villagers continue to be educated about rare breeds.
He said the an incentive program, rewarding people with $10 for finding turtle nests and $6 per hatchling, had populated the conservation centre with about 100 turtles so far.
Main features of the new facility include 33 aquatic tanks as well as a large concrete pond, where one adult Cantor's Giant Soft-shelled turtle is being displayed.
Partners of the turtle conservation effort include Conservation International, Cambodia's Fisheries Administration and 100 Pillar Pagoda, in addition to the World Wildlife Fund and the Association of Buddhist Monks.
6/10/11, by Kenneth Ingram and Phak Seangly, The Phnom Penh Post - Cambodia's Newspaper of Record:
Snapping at monks and government officials with jaws capable of shredding through bone, a rare adult Cantor's Giant Soft-Shelled turtle was one of 100 reptiles given a new home at a conservation centre that aims to boost dwindling turtle populations in Cambodia.
The US$20,000 Mekong Turtle Conservation Centre, constructed by NGO Conservation International within the confines of 100 Pillar pagoda in Kartie province's Sambro district, opened on Wednesday. It is intended as a sanctuary for four different types of turtles, including two endangered species, and contains facilities for raising baby turtles away from predators and researching the reptiles further.
Among the endangered reptiles are Cantor's Giant Soft-shelled turtles, with individuals known to weigh over 110 pounds and two meters in length. Featuring a distinct snout that earns it the name of 'frog head turtle' in Khmer, the breed inhabits the depths of freshwater streams and inland slow-moving river systems, feeding primarily on aquatic plants, fish, crab and shrimp.
The turtles - thought to be extinct in Vietnam and on the brink of extinction in Thailand and Laos - were virtually undetected in Cambodia until a biological survey, conducted in 2007, gained international attention for spotting them in a pristine natural habitat along the Mekong River. The discovery was an impetus for the new conservation centre.
"This centre will provide turtles with a safe environment to mature before they are introduced to the wild," project associate of Conservation International Sun Yoeung said, adding that baby turtles would be released once they reached between 10 months and two years old.
However, 15 four-day-old Cantor's turtles were released into the river yesterday, a Conservation International spokeswoman said, in part to facilitate the filming of a nature programme by French filmmakers.
"We don't want to take all of the hatchlings back to the centre because we don't know if they will all survive [there]," explained Som Sitha, monitoring and evaluation coordinator at Conservation International, pointing out that Cantor's turtles had never been raised in captivity before. "Also, we want to involve local fishermen and show them that we will release some turtles back into their habitat."
Sun Yoeung, 33, project associate of Conservation International, said human activity remained the greatest threat to turtle habitats.
"Turtle nests are easily found by people because of the large tracks that adults leave in the sand," he said. "People were eating the eggs, but this is less common now because of education about turtles."
Turtles are also sold to markets as ingredients for traditional Chinese medicines, ornaments and pets.
Environmentalists also attribute human activity to the destruction and pollution of turtle habitats through fishing, farming, small-scale mining near the Mekong River.
Community partnerships have been central to the success of the conservation effort thus far, said Sun Yoeung, as fishermen and villagers continue to be educated about rare breeds.
He said the an incentive program, rewarding people with $10 for finding turtle nests and $6 per hatchling, had populated the conservation centre with about 100 turtles so far.
Main features of the new facility include 33 aquatic tanks as well as a large concrete pond, where one adult Cantor's Giant Soft-shelled turtle is being displayed.
Partners of the turtle conservation effort include Conservation International, Cambodia's Fisheries Administration and 100 Pillar Pagoda, in addition to the World Wildlife Fund and the Association of Buddhist Monks.
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