Immunolocalization of beta‐proteins and alpha‐keratin in the epidermis of the soft‐shelled turtle explains the lack of formation of hard corneous material

Immunolocalization of beta‐proteins in the epidermis of the soft‐shelled turtle explains the lack of formation of hard corneous material, Acta Zoologica, Stockholm. The corneous layer of soft‐shelled turtles derives from the accumulation of higher ratio of alpha‐keratins versus beta‐proteins as indicated by gene expression, microscopic, immunocytochemical and Western blotting analysis. Type I and II beta‐proteins of 14–16 kDa, indicated as Tu2 and Tu17, accumulate in the thick and hard corneous layer of the hard‐shelled turtle, but only type II is present in the thinner corneous layer of the soft‐shelled turtle. The presence of proline–proline and proline–cysteine–hinge dipeptides in the beta‐sheet region of all type II beta‐proteins so far isolated from the epidermis of soft‐shelled turtles might impede the formation of beta‐filaments and of the hard corneous material. Western blot analysis suggests that beta‐proteins are low to absent in the corneous layer. The ultrastructural immunolocalization of Tu2 and Tu17 beta‐proteins shows indeed that a diffuse labelling is seen among the numerous alpha‐keratin filaments present in the precorneous and corneous layers of the soft epidermis and that no dense corneous material is formed. Double‐labelling experiments confirm that alpha‐keratin prevails on beta‐proteins. The present observations support the hypothesis that the soft material detected in soft‐shelled turtles derives from the prevalent activation of genes producing type II beta‐proteins and high levels of alpha‐keratins.     

An Outbreak of Trichinellosis by Consumption of Raw Soft-Shelled Turtle Meat in Korea

Trichinellosis transmission to humans via the consumption of reptile meat is rare worldwide. In Korea, however, 2 such outbreaks, possibly via consumption of soft-shelled turtle meat, have occurred in 2 successive years. In 17 August 2014, 6 patients were admitted to Wonju Severance Christian Hospital complaining of myalgia, fever, and headache. Eosinophilia was the indication of the initial laboratory results, and they were eventually diagnosed as trichinellosis by ELISA. All of the patients worked at the same company and had eaten raw soft-shelled turtle meat at a company dinner 10 days prior to their admission. They were treated with albendazole for 2 weeks, upon which all of their symptoms disappeared. This is the 8th report on human trichinellosis in Korea, and the second implicating raw soft-shelled turtle meat.     

Not putting all their eggs in one basket: bet‐hedging despite extraordinary annual reproductive output of desert tortoises

Bet‐hedging theory makes the counter‐intuitive prediction that, if juvenile survival is low and unpredictable, organisms should consistently reduce short‐term reproductive output to minimize the risk of reproductive failure in the long‐term. We investigated the long‐term reproductive output of an Agassiz's desert tortoise (Gopherus agassizii) population and conformance to a bet‐hedging strategy of reproduction in an unpredictable but comparatively productive environment. Most females reproduced every year, even during periods of low precipitation and poor germination of food plants, and the mean percentage of reproducing females did not differ significantly on an annual basis. Although mean annual egg production (clutch size × clutch frequency) differed significantly among years, mean clutch size and mean clutch frequency remained relatively constant. During an El Niño year, mean annual egg production and mean annual clutch frequency were the highest ever reported for this species. Annual egg production was positively influenced by maternal body size but clutch size and clutch frequency were not. Our long‐term results confirm earlier conclusions based on short‐term research that desert tortoises have a bet‐hedging strategy of producing small clutches almost every year. The risk of long‐term reproductive failure is minimized in unpredictable environments, both through time by annually producing multiple small clutches over a long reproductive lifespan, even in years of low resource availability, and through space by depositing multiple annual clutches in different locations. The extraordinary annual reproductive output of this population appears to be the result of a typically high but unpredictable biomass of annual food plants at the site relative to tortoise habitat in dryer regions. Under the comparatively productive but unpredictable conditions, tortoises conform to predictions of a bet‐hedging strategy of reproduction with relatively small but consistent clutch sizes. Published 2015. This article is a U.S. Government work and is in the public domain in the USA, Biological Journal of the Linnean Society, 2015, 115 , 399–410.     

Extreme temperatures,foundation species,and abrupt ecosystem change: an example from an iconic seagrass ecosystem

Extreme climatic events can trigger abrupt and often lasting change in ecosystems via the reduction or elimination of foundation (i.e., habitat‐forming) species. However, while the frequency/intensity of extreme events is predicted to increase under climate change, the impact of these events on many foundation species and the ecosystems they support remains poorly understood. Here, we use the iconic seagrass meadows of Shark Bay, Western Australia – a relatively pristine subtropical embayment whose dominant, canopy‐forming seagrass, Amphibolis antarctica, is a temperate species growing near its low‐latitude range limit – as a model system to investigate the impacts of extreme temperatures on ecosystems supported by thermally sensitive foundation species in a changing climate. Following an unprecedented marine heat wave in late summer 2010/11, A. antarctica experienced catastrophic (>90%) dieback in several regions of Shark Bay. Animal‐borne video footage taken from the perspective of resident, seagrass‐associated megafauna (sea turtles) revealed severe habitat degradation after the event compared with a decade earlier. This reduction in habitat quality corresponded with a decline in the health status of largely herbivorous green turtles (Chelonia mydas) in the 2 years following the heat wave, providing evidence of long‐term, community‐level impacts of the event. Based on these findings, and similar examples from diverse ecosystems, we argue that a generalized framework for assessing the vulnerability of ecosystems to abrupt change associated with the loss of foundation species is needed to accurately predict ecosystem trajectories in a changing climate. This includes seagrass meadows, which have received relatively little attention in this context. Novel research and monitoring methods, such as the analysis of habitat and environmental data from animal‐borne video and data‐logging systems, can make an important contribution to this framework.     

Field observation of predation on a turtle by a giant water bug

The giant water bug, subfamily Lethocerinae, which has the largest body size among Belostomatidae, is known to be a vertebrate specialist that preys upon fish, amphibians and snakes. However, there have been no reports concerning predation on a turtle by Lethocerinae. Here, I report that a male giant water bug Kirkaldyia (Lethocerus) deyrolli (Heteroptera: Belostomatidae) (58.09 mm in total length) was catching hold of a turtle Chinemys reevesii (34.14 mm in carapace length) in a ditch adjoining a paddy rice field. This is a first report of K. deyrolli eating a turtle.     

Sister group relationship of turtles to the bird-crocodilian clade revealed by nuclear DNA-coded proteins

The phylogenetic position of turtles is a currently controversial issue. Recent molecular studies rejected a traditional view that turtles are basal living reptiles (Hedges, S. B., and L. L. Poling. 1999. A molecular phylogeny. Science 83:998-1001; Kumazawa, Y., and M. Nishida. 1999. Complete mitochondrial DNA sequences of the green turtle and blue-tailed mole skink, statistical evidence for archosaurian affinity of turtles. Mol. Biol. Evol. 16:784-792). Instead, these studies grouped turtles with birds and crocodiles. The relationship among turtles, birds, and crocodiles remained unclear to date. To resolve this issue, we have cloned and sequenced two nuclear genes encoding the catalytic subunit of DNA polymerase alpha and glycinamide ribonucleotide synthetase-aminoimidazole ribonucleotide synthetase-glycinamide ribonucleotide formyltransferase from amniotes and an amphibian. The amino acid sequences of these proteins were subjected to a phylogenetic analysis based on the maximum likelihood method. The resulting tree showed that turtles are the sister group to a monophyletic cluster of archosaurs (birds and crocodiles). All other possible tree topologies were significantly rejected.     

Conservation Genetics of the East Pacific Green Turtle (Chelonia mydas) in Michoacan, Mexico

The main continental nesting rookeries of the east Pacific green turtle (EPGT), Chelonia mydas, on the Michoacan (Mexico) coast suffered drastic population declines following intense exploitation in the 1960s--1970s with annual abundance of nesting females plummeting from about 25,000 to an average of about 1400 between 1982 and 2001. Analyses of data from three nDNA microsatellite loci and 400 bp mtDNA control region sequences from a total of 123 nesting females sampled from four Michoacan rookeries found no evidence of population sub-structuring. The recent order of magnitude reduction in the population size shows no apparent impact on genetic diversity in either control region sequences (overall h = 0.48; pi = 0.0036) or microsatellite loci (overall Na = 20.8; Hexp = 0.895). Our estimates of annual effective female population size (Nef; from theta = 2Nemicron) of 1.9-2.3 x 10(3), in spite of being an order of magnitude below historical records, appear to be sufficient to allow recovery of this population without significant loss of genetic diversity. These findings highlight the importance of continued conservation to reverse the decline of this population before it becomes vulnerable to genetic erosion.     

Amino Acid Sequence and Activity of Green Turtle (Chelonia mydas) Lysozyme

Green turtle lysozyme purified from egg white was sequenced and analyzed its activity. Lysozyme was reduced and pyridylethylated or carboxymethylated to digest with trypsin, chymotrypsin and V8 protease. The peptides yielded were purified by RP-HPLC and sequenced. Every trypsin peptide was overlapped by chymotrypsin peptides and V8 protease peptides. This lysozyme is composed of 130 amino acids including an insertion of a Gly residue between 47 and 48 residues when compared with chicken lysozyme. The amino acid substitutions were found at subsites E and F. Namely Phe34, Arg45, Thr47, and Arg114 were replaced by Tyr, Tyr, Pro, and Asn, respectively. The time course using N-acetylglucosamine pentamer as a substrate showed a reduction of the rate constant of glycosidic cleavage and transglycosylation and increase of binding free energy for subsite E, which proved the contribution of amino acids mentioned above for substrate binding at subsites E and F.