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Li S.,National University of Singapore | Li S.,CAS Wuhan Institute of Hydrobiology | Li S.,Chinese Academy of Sciences | Wang D.,CAS Wuhan Institute of Hydrobiology | And 7 more authors.
Journal of Experimental Biology | Year: 2013

The hearing and echolocation clicks of a stranded Indo-Pacific humpback dolphin (Sousa chinensis) in Zhuhai, China, were studied. This animal had been repeatedly observed in the wild before it was stranded and its age was estimated to be ∼40years. The animal's hearing was measured using a non-invasive auditory evoked potential (AEP) method. Echolocation clicks produced by the dolphin were recorded when the animal was freely swimming in a 7.5m (width)×22m (length)×4.8m (structural depth) pool with a water depth of ∼2.5m. The hearing and echolocation clicks of the studied dolphin were compared with those of a conspecific younger individual, ∼13years of age. The results suggested that the cut-off frequency of the high-frequency hearing of the studied dolphin was ∼30-40kHz lower than that of the younger individual. The peak and centre frequencies of the clicks produced by the older dolphin were ∼16kHz lower than those of the clicks produced by the younger animal. Considering that the older dolphin was ∼40years old, its lower high-frequency hearing range with lower click peak and centre frequencies could probably be explained by age-related hearing loss (presbycusis). © 2013. Published by The Company of Biologists Ltd.


Jin W.,Sun Yat Sen University | Jia K.,Sun Yat Sen University | Yang L.,Sun Yat Sen University | Chen J.,Pearl River Estuary Chinese White Dolphin National Nature Reserve | And 2 more authors.
In Vitro Cellular and Developmental Biology - Animal | Year: 2013

The marine mammalian Indo-Pacific humpback dolphin, once widely lived in waters of the Indian to western Pacific oceans, has become an endangered species. The individual number of this dolphin has significantly declined in recent decades, which raises the concern of extinction. Direct concentration on laboratorial conservation of the genetic and cell resources should be paid to this marine species. Here, we report the successful derivation of cell lines form the skin of Indo-Pacific humpback dolphin. The cell cultures displayed the characteristics of fibroblast in morphology and grew rapidly at early passages, but showed obvious growth arrest at higher passages. The karyotype of the cells consisted of 42 autosomes and sex chromosomes X and Y. The immortalized cell lines obtained by forced expression of the SV40 large T-antigen were capable of proliferation at high rate in long-term culture. Immortalization and long-term culture did not cause cytogenetically observable abnormality in the karyotype. The cell type of the primary cultures and immortalized cell lines were further characterized as fibroblasts by the specific expression of vimentin. Gene transfer experiments showed that exogenetic genes could be efficiently delivered into the cells by both plasmid transfection and lentivirus infection. The cells derived from the skin of the Indo-Pacific humpback dolphin may serve as a useful in vitro system for studies on the effects of environmental pollutants and pathogens in habitats on the dolphin animals. More importantly, because of their high proliferation rate and susceptibility to lentivirus, these cells are potential ideal materials for generation of induced pluripotent stem cells. © 2013 The Society for In Vitro Biology.


Lin W.,Sun Yat Sen University | Zhou R.,Sun Yat Sen University | Porter L.,University of Hong Kong | Chen J.,Pearl River Estuary Chinese White Dolphin National Nature Reserve | Wu Y.,Sun Yat Sen University
Molecular Phylogenetics and Evolution | Year: 2010

Taxonomy within genus Sousa is confused largely due to inconsistencies among external morphology, skull morphology, pigmentation patterns and molecular studies. Here we provide our understanding of the evolution of Sousa chinensis by proposing a phylogeographic history based on mtDNA study. It is proposed that the species originated in eastern Australian waters and the current distribution has taken shape over the last 8.02-1.24 million years. Populations in Southeast Asia and Australian region experienced recent expansion about 0.54-1.5 million years ago. It is also proposed that populations in Southeast Asia experienced separation, re-unification and further dispersal during the last glacial age with multiple north-south migration across the Sahul Shelf area of northern Australia. © 2010 Elsevier Inc.


Huang S.-L.,Sun Yat Sen University | Huang S.-L.,National Taiwan Ocean University | Karczmarski L.,University of Hong Kong | Chen J.,Pearl River Estuary Chinese White Dolphin National Nature Reserve | And 5 more authors.
Biological Conservation | Year: 2012

Estimates of demographic parameters and predictive modeling of population viability furnish baseline evidence for informed management of species and populations. There are very few examples of such approaches involving cetaceans due to often limited fundamental data, which frequently impairs the effectiveness of conservation. In this study, we estimate demographic parameters for the Indo-Pacific humpback dolphins, Sousa chinensis, from the Pearl River Estuary (PRE), China, based on a life-table constructed using data from stranded animals. We apply current abundance estimates and use an individual-based Leslie-matrix model to predict the population fluctuation by factoring in parameter uncertainty and demographic stochasticity. Our estimates indicate a continuous rate of population decline of 2.46% per annum, albeit with considerable variation. If the estimated rate of decline remains constant, 74.27% of the current population is projected to be lost after three generations and 57.60% of model simulations meet the criteria for classification as endangered under Criterion A3, applying IUCN Red List Categories and Criteria Version 3.1. However, as PRE is among the fastest economically growing regions of China and the world, the estimated rate of decline may further accelerate in a near future and the projected risk of extinction may be higher. Effective conservation measures are much needed and should be seen as a matter of urgency in management plans targeting PRE and environs. © 2012 Elsevier Ltd.


Lin W.,Sun Yat Sen University | Chang L.,Sun Yat Sen University | Frere C.H.,University of Queensland | Zhou R.,Sun Yat Sen University | And 3 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2012

Estimating the degree of isolation or gene flow is central to understanding population dynamics and conservation. In this study, we used both mitochondrial and nuclear markers to investigate the genetic structure of Indo-Pacific humpback dolphins (genus Sousa) in China. Contrary to previous photo-identification and genetic studies, we found no evidence for population genetic structure or inter-population gene flow across the geographical scale examined. Significant inbreeding, which seems to support genetic isolation to some extent, was within expectation as a result of low genetic diversity in a random-mating system. Overall, the Indo-Pacific humpback dolphins in China were characterized by low genetic diversity on both maternal and bi-parental markers. While significant steps have been taken towards implementing marine reserves, our study highlights the critical need for fine-scale genetic and ecological monitoring programs and a coordinated approach to secure the survival of Indo-Pacific humpback dolphins in Chinese waters. © 2012 Elsevier B.V.

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