Phylogeographic patterns and conservation implications of the endangered Chinese giant salamander.

Understanding genetic diversity patterns of endangered species is an important premise for biodiversity conservation. The critically endangered salamander Andrias davidianus, endemic to central and southern mainland in China, has suffered from sharp range and population size declines over the past three decades. However, the levels and patterns of genetic diversity of A. davidianus populations in wild remain poorly understood. Herein, we explore the levels and phylogeographic patterns of genetic diversity of wild-caught A. davidianus using larvae and adult collection with the aid of sequence variation in (a) the mitochondrial DNA (mtDNA) fragments (n = 320 individuals; 33 localities), (b) 19 whole mtDNA genomes, and (c) nuclear recombinase activating gene 2 (RAG2; n = 88 individuals; 19 localities). Phylogenetic analyses based on mtDNA datasets uncovered seven divergent mitochondrial clades (A-G), which likely originated in association with the uplifting of mountains during the Late Miocene, specific habitat requirements, barriers including mountains and drainages and lower dispersal ability. The distributions of clades were geographic partitioned and confined in neighboring regions. Furthermore, we discovered some mountains, rivers, and provinces harbored more than one clades. RAG2 analyses revealed no obvious geographic patterns among the five alleles detected. Our study depicts a relatively intact distribution map of A. davidianus clades in natural species range and provides important knowledge that can be used to improve monitoring programs and develop a conservation strategy for this critically endangered organism.

Mitochondrial DNA sequence of Onychostoma rara.

The complete mitochondrial genome sequence of Onychostoma rara was determined to be 16,590 bp in length and contains 13 protein-coding genes (PCGs), 22 tRNA genes, large (rrnL) and small (rrnS) rRNA and the non-coding control region. Its total A + T content is 55.65%. We also analyzed the structure of control region, 6 CSBs (CSB-1, CSB-2, CSB-3, CSB-D, CSB-E and CSB-F) and 2 bp tandem repeat were detected.

[Effects of low concentration of chlorpyrifos prenatal exposure on generation mouse brain hippocampus and somatosensory cortex].

OBJECTIVE: To observe the effects of low concentration of organophosphate pesticide chlorpyrifos (CPF) prenatal exposure on generation mouse brain development. METHODS: 5 mg/kg CPF was administered daily on gestation days (GD) 7.5 - 11.5. On postnatal day (PD) 35, quantitative morphologic examines were measured in CA1, CA3, dentate gyrus regions of the hippocampus and somatosensory cortex. RESULTS: After CPF prenatal exposure, selective morphology impairments were observed, showing 22.37%, 25.66% thinning of the CA1 and CA3 layers, 24.14% enlargement of the dentate guys and 81.77% to 74.61% decreasing of the ratio of neuron/glial of the somatosensory cortex. CONCLUSION: There maybe slight morphological changes after prenatal low concentration pesticide exposure even without obviously systemic toxicity.