Salamander Andrias Davidianus Research Articles

Quality Characteristics and Moisture Mobility of Giant Salamander (Andrias davidianus) Jerky during Roasting Process

Quality attributes and water mobility of giant salamander jerkies (GSJs) during roasting process (160°C, for 0, 20, 40, 60, and 80 min) were investigated. The results showed that a ∗ , b ∗ values and shear force increased of GSJs roasting from 20 to 80 min, while L ∗ , yield, and moisture content decreased significantly ( p < 0.05 ). Sensory assessment showed that GSJs at a roasting time of 40–60 min had higher scores. GSJs contained great amount of healthy unsaturated fatty acids (including DHA and EPA), and the total amino acids and essential amino acids were among 59.33–71.77 g·100 g−1 and 25.94–31.40 g·100 g−1, respectively. The mobility of the immobilized moisture and free moisture were shrunk dramatically during roasting. The proton density weighted images also exhibited the moisture shrinkage during roasting. In addition, T22 and T23 were positively correlated with MRI signal, moisture content, and yield of GSJs, but negatively correlated with shear force and overall acceptability, respectively. Thus, in view of various quality attributes and sensory evaluation, a roasting time of 40–60 min was favored for nutritive GSJs production. LF-NMR and MRI might be employed to profile the quality characteristics during roasting as a rapid and nondestructive analytical tool.

Spatial distribution and seasonal movement patterns of reintroduced Chinese giant salamanders

BackgroundVery little is known about the temporal or spatial movement patterns of Chinese giant salamanders (Andrias davidianus) due to their rarity, remote habitat and secretive nature. Commercial breeding farms provide a unique opportunity as a source of animals for reintroduction and spatial ecology studies, which will help inform conservation management efforts for this threatened species. We surgically implanted radio transmitters into the body cavity of 31 juvenile giant salamanders, and these salamanders were subsequently released into two small river systems (Donghe and Heihe Rivers) located in the Qinling Mountains of central China and were monitored daily from May 2013 to August 2014.ResultsOnly two salamanders survived through the end of the project at the Heihe River compared with 12 at the Donghe River, thus movement data for salamanders released at the Heihe river are described individually. The overall sedentariness (ratio of no movement to all observations) for the two salamanders at the Heihe River was 0.29 and 0.28 compared to the average sedentariness of 0.26 ± 0.01 for the 12 salamanders at the Donghe River. Mean daily movement was 15.4 m ± 0.7 at the Heihe River compared to 9.3 m ± 0.3 at the Donghe River. Overall linear home range (LHR) was 246 m and 392 m for the two salamanders at the Heihe River, compared with a mean LHR of 227.2 m ± 70.5 at the Donghe River. The Donghe salamanders exhibited different movement patterns across seasons, having higher sedentariness, shorter daily movement, and smaller LHR in winter than in summer. Up-stream dispersal and fidelity to release site were recorded at both rivers. The mean dispersal distance for the Donghe River salamanders was 145.3 m ± 61.9, while the two surviving salamanders at the Heihe River had a dispersal distance of 211 m and 205 m.ConclusionsThis project provides important insights on the movement ecology of a large aquatic salamander species, and in particular, our results may assist with reintroduction efforts by developing best management practices on when and where to release animals as a conservation strategy.

Characterization and Functional Properties of Gelatin Extracted from Chinese Giant Salamander (Andrias Davidianus) Skin

ABSTRACTThe characteristics and functional properties of gelatin obtained from Chinese giant salamander (Andrias davidianus) skin were investigated. After alkaline and acetic acid pre-treatment, yield of the gelatin by hot water extraction (60°, 8 h) was 17.63 g/100 g (wet basis), and the gelatin contained 89.46 g/100 g protein, 0.3 g/100 g fat, and 0.41 g/100 g ash (dry basis). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results of the gelatin showed clear band pattern for collagen subunits,β- and α-chains. The gelatin contained 18.85% imino acids, 28.62% hydrophobic amino acids, and 19.68% essential amino acids, which is slightly lower than porcine skin gelatin (PSG). The gelatin exhibited thermo-reversible properties, with gel strength of 192.50 ± 11.47 g, rupture distance of 10.17 ± 0.20 mm, gelling temperature of 4.98°, and melting temperature of 18.04°, Emulsifying activity index (EAI) of the gelatin diminished with increasing concentrations from 10 to 40 mg/mL (p < .05), whereas the emulsifying stability index (ESI) improved significantly (p < .05). Higher concentrations (30 and 40 mg/mL) could significantly enhance the gelatin’s foam expansion (FE) and foam stability (FS) (p < .05). Water absorption ability and oil absorption ability of the gelatin were 7.1 g water/g gelatin and 9.8 g oil/g gelatin, respectively. These results imply that the gelatin with good interfacial properties could potentially be used as a novel ingredient in food emulsion systems.Abbreviations: CGSS, Chinese giant salamander skin; CSG, Chinese giant salamander skin gelatin; PSG, porcine skin gelatin; EAI, emulsion activity index; ESI, emulsion stability index; FE, foam expansion; FS, foam stability; WAC, water absorption capacity; OAC, oil absorption capacity.

Identification and Сharacteristics of Conserved miRNA in Testis Tissue from Chinese Giant Salamander (Andrias davidianus) by Deep Sequencing

MicroRNAs (miRNAs) are a family of ∼22-nucleotide, non-coding, single-stranded RNA molecules, which are considered as key regulators of gene expression and regulate various biological processes including gonad development, differentiation and dimorphism. Although most miRNAs studied have been identified in animals, relatively limited knowledge also exist on amphibian species. Identification of the full repertoire of miRNAs in testes of Andrias davidianus would significantly increase our knowledge on miRNA physiological functions of miRNA in gonads. In this study, a small RNA library was constructed from adult A. davidianus testis tissue and sequenced using the deep sequencing. As a result, 26 401 474 clean reads was obtained, and 1340 known conserved miRNAs were identified. Additionally, expression of 12 randomly selected miRNAs was confirmed by stem-loop qRT-PCR from 5 different tissues of A. davidianus. Of them, aca-miR-99b-5p, xtr-miR-10c, and cfa-miR-363 were highly expressed in testes. Although the physiological functions of these expressed miRNAs were still not revealed, their expression patterns indicate that they are likely to play a role in growth and development of A. davidianus testes, which is needed to be further study for confirmation. The results of this study will help in gaining understanding of the role of miRNAs in the regulation of A. davidianus reproductive system.

Identification and Characterization of MicroRNAs in Skin of Chinese Giant Salamander (Andrias davidianus) by the Deep Sequencing Approach.

MicroRNAs (miRNA) play a pivotal role in regulating a broad range of biological processes, acting by cleaving mRNAs or by translational repression. However, the miRNAs from skin of Andrias davidianus have not been reported. In this study, a small-RNA cDNA library was constructed and sequenced from skin of A. davidianus. A total of 513 conserved miRNAs belonging to 174 families were identified. The remaining 108 miRNAs we identified were novel and likely to be skin tissue-specific but were expressed at low levels. The presence of randomly selected 15 miRNAs identified and their expression in eight different tissues from A. davidianus were validated by stem-loop qRT-PCR. For better understanding the functions of miRNAs, 129,791 predicated target genes were analyzed by GO and their pathways illustrated by KEGG pathway analyses. The results show that these identified miRNAs from A. davidianus skin are involved in a broad range of physiological functions including metabolism, growth, development, and immune responses. This study exhaustively identifies miRNAs and their target genes, which will ultimately pave the way for understanding their role in skin of A. davidianus and other amphibians. Further studies are necessary to better understand miRNA-mediated gene regulation.

Molecular cloning, characterization and evolutionary analysis of leptin gene in Chinese giant salamander, Andrias davidianus

AbstractLeptin is an important hormone possessing diverse physiological roles in mammals and teleosts. However, it has been characterized only in a few amphibian species, and its evolutions are still under debate. Here, the full length of the leptin (Adlep) cDNA of Chinese giant salamander (Andrias davidianus), an early diverging amphibian species, is characterized and according to the results of the primary sequence analysis, tertiary structure reconstruction and phylogenetic analysis is confirmed to be an ortholog of mammalian leptin. An intron was identified between the coding exons of A. davidianus leptin, which indicated that the leptin is present in the salamander genome and contains a conserved gene structure in vertebrates. Adlep is widely distributed but expression levels vary among different tissues, with highest expression levels in the muscle. Additionally, the leptin receptor and other genes were mapped to three known leptin signaling pathways, suggesting that the leptin signaling pathways are present in A. davidianus. Phylogenetic topology of leptins are consistent with the generally accepted evolutionary relationships of vertebrates, and multiple leptin members found in teleosts seem to be obtained through a Cluopeocephala-specific gene duplication event. Our results will lay a foundation for further investigations into the physiological roles of leptin in A. davidianus.

Functional characterization of a short peptidoglycan recognition protein from Chinese giant salamander (Andrias davidianus).

Peptidoglycan (PGN) recognition proteins (PGRPs) are important pattern recognition receptors (PRRs) involved in immune defense against bacterial infections. In this study, a short PGRP (termed AdPGRP-S1) was cloned and functionally characterized from Chinese giant salamander (Andrias davidianus), the largest extant urodela amphibian species. AdPGRP-S1 was 184 aa in length and shared 38.7%-54.9% sequence identities with other vertebrates’ short PGRPs. It contained one typical PGRP domain at the C-terminal region and several conserved amino acid (aa) residues involved in amidase and PGN binding. AdPGRP-S1 was constitutively expressed in all tissues examined, with the highest expression level seen in spleen and intestine. It has been shown that AdPGRP-S1 could bind and degrade Lys-PGN and Dap-PGN. Further, AdPGRP-S1 had antibacterial activity against the Gram-negative bacteria, Edwardsiella tarda, and was able to trigger the activation of NF-κB signaling. These results demonstrated that AdPGRP-S1 possesses multiple functions in pathogen recognition, mediating ceullular signaling, and initiating antibacterial response. This is the first functional study of a salamander PGRP, providing insight to further understand the functional evolution of verterbates’ PGRPs.

Identification and characterization of the Chinese giant salamander (Andrias davidianus) miRNAs by deep sequencing and predication of their targets

MicroRNAs (miRNAs) are non-coding small RNA of approximately 22 nt in length. They are considered as key regulators for gene expression at the post-transcriptional level and play an important role in the regulation of many fundamental biological processes. Andrias davidianus, as one of the largest amphibian on earth, may represent the transitional type of animal from aquatic to terrestrial life, but so far, no miRNA has been identified in the species. In this study, Illumina deep sequencing was used for high-throughput analysis of miRNAs in a pooled small RNA library isolated from eight tissues sample of A. davidianus including the spleen, liver, muscle, kidney, skin, testis, gut, and heart. In total, 6,213,146 reads were obtained, 5,962,175 of which were related to 143 unique miRNAs, including 140 conserved and three novel A. davidianus-specific miRNAs. Among them, seven conserved miRNAs and one novel miRNA were selected to validate their expression pattern by stem-loop qRT-PCR. Moreover, 4700 potential target genes were predicted for 143 A. davidianus miRNAs; GO enrichment analysis and KEGG pathway showed that most of the targets are involved in diverse biological processes including ubiquitin-mediated proteolysis, FOXO signaling pathway, tight junction, and spliceosome. This study provides the first large-scale identification and characterization of A. davidianus miRNAs, and predicted their potential target genes; it will lay a valuable foundation for future understanding the role of these miRNAs on regulating diverse biological processes.

Structural insights into ligand binding of PGRP1 splice variants in Chinese giant salamander (Andrias davidianus) from molecular dynamics and free energy calculations.

Peptidoglycan (PGN) recognition proteins (PGRPs) are important pattern recognition receptors of the innate immune system. A number of PGRP splicing variants produced by alternative splicing of PGRP genes have been reported. However, several important aspects of interactions between PGRP splice variants and their ligands are still unclear. In the present study, three dimensional models of salamander PGRP1 (adPGRP1) and its splice variant (adPGRP1a) were constructed, and their key amino acids involved in interacting with PGNs were analyzed. The results revealed that adPGRP1a has a typical PGRPs structure containing five β-sheets and four α-helices, while adPGRP1 contained five β-sheets and only one α-helix due to the lack of 51 amino acids at its C-terminus. Molecular docking revealed that van der Waals and Coulombic interactions contributed to interactions in the protein-ligand complex. Further binding energy of adPGRP-PGNs computed by the MM-PBSA method revealed that adPGRP1a and adPGRP1 might selectively bind to different PGNs; the former might selectively bind Dap-type PGNs and the latter both types of PGNs. In addition, the binding energy of each residue of adPGRP1a and adPGRP1 was also calculated, revealing that residues involved in the interaction of protein-ligand complexes were different in adPGRP1a and adPGRP1. These results provided a first insight into the potential basis for interaction between PGRPs generated by alternative splicing and PGN derivatives.

Genetic diversity of Chinese giant salamander (Andrias davidianus) based on the novel microsatellite markers

Chinese giant salamander (Andrias davidianus) is a rare amphibian species in the world. Microsatellite markers are a promising tool for accurate estimation population structure and genetic diversity. In this paper, we isolated novel microsatellite marker for Chinese giant salamander using fast isolation by AFLP of sequences containing repeats (FIASCO) method. More than 50% sequences in 132 clones had repeat number over ten times with di or trinucleeotide repeat except of (GA)12. Seventy pairs of primers were designed and eleven polymorphic microsatellite loci were characterized for wild and cultivated Chinese giant salamander populations. The allele number was from 3 to 9 in different loci. Polymorphism information content was from 0.544 to 0.702 in cultivated population. The results implied more alleles and PIC were in the wild population than cultivated population. The observed heterozygosities in two populations were higher than 0.553. The data analysis suggested that the cultivated population has lower genetic diversity than wild population, which it’s perhaps owing to inbreeding in artificial breeding. To our knowledge, it’s the first time to isolated microsatellite markers for Chinese giant salamander. The result indicated that the markers were suitable for the population genetic analysis of Chinese giant salamander.

Effectiveness of releasing artificially-bred Chinese giant salamander(Andrias davidianus) into the wild in Zhangjiajie,Hunan

Effectiveness of releasing artificially-bred Chinese giant salamander(Andrias davidianus) into the wild in Zhangjiajie,Hunan

Ultrastructure of the skin mechanoreceptors of the Chinese giant salamander, Andrias davidianus.

The ultrastructure of two kinds of mechanoreceptive organs, pit organs and neuromasts, in the skin of adult giant salamanders (Andrias davidianus) was studied by transmission electron microscopy. Neuromasts and pit organs differ in their types of synapses, the spatial distribution of kinocilia on sensory cells, and in the degree to which sensory cells are separated by processes of the supporting cells; the two organs probably serve complementary functions. The neuromasts in A. davidianus differ from those of other salamanders in the orientation of kinocilia, in the extent of intrusion of supporting cells into the sensory layer, in the degree of thickening of the synaptic membranes, in the distribution of synaptic spheres, and by the absence of a cupula.