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Does the Dzungarian racerunner (Eremias dzungarica Orlova, Poyarkov, Chirikova, Nazarov, Munkhbaatar, Munkhbayar & Terbish, 2017) occur in China? Species delimitation and identification with DNA barcoding and morphometric analyses
, Available online , doi: 10.24272/j.issn.2095-8137.2020.318
The Eremias multiocellata-przewalskii species complex is a viviparous group in the genus Eremias, and a well-known representative of taxonomically complicated taxa. Within this complex, a new species – E. dzungarica (
Orlova et al., 2017) – has been described recently from western Mongolia and eastern Kazakhstan, with an apparent distribution gap in northwestern China. In this study, we used an integrative taxonomic framework to address whether E. dzungarica indeed occurs in China. Thirty specimens previously classified as E. multiocellata were collected in eastern Kazakhstan and the adjacent Altay region in China. The cytochrome c oxidase I (COI) barcodes were sequenced and compiled with those from Orlova et al. (2017) and analyzed with the standard and diverse barcoding techniques. We detected an absence of a barcoding gap in this complex, which indicates potential cryptic species in Eremias sp. 3 with high intraspecific diversity and multiple recently evolved species in Clade A. Both BIN and GMYC suggested an unrealistically large number of species (23 and 26, respectively), while ABGD, mPTP and BPP indicated a more conservative number of species (10, 12, and 15, respectively), largely concordant with the previously defined species-level lineages according to phylogenetic trees. Based on molecular phylogeny and morphological examination, all 30 individuals collected in this study were reliably identified as E. dzungarica – a distinct species – confirming the occurrence of this species in the Altay region, Xinjiang, China. Potentially owing to the larger sample size in this study, our morphological analyses revealed many inconsistencies with the original descriptions of E. dzungarica, which were primarily associated with sexual dimorphism and a broader range of values for various traits.
α-crystallins are small heat shock proteins, function as molecular chaperones to inhibit the misfolding and aggregation of β/γ-crystallins. Genetic mutations of CRYAA are associated with protein aggregation and cataract occurance. One possible mechanism causing cataract is that endoplasmic reticulum stress (ERS) induces unfolded protein response (UPR) and eventually leads to apoptosis. However, the underlying pathogenic mechanism has not been explored. Here, we successfully constructed cataract-causing mutant CRYAA (Y118D) related mouse model and the lens of CRYAA-Y118D mutant mouse showed severe posterior rupture, abnormal morphological changes and aberrant arrangement in crystallin fibers. Histological results were consistent with the clinical pathological characteristics. Further, we explored pathogenic factors in cataract development process through transcriptome analysis. Key pathway analysis showed that up-regulated genes in CRYAA-Y118D mutant mouse were implicated in ERS-UPR pathway. The findings of this study show that prolonged activation of UPR pathway and severe stress response causes proteotoxic and ERS-induced cell death in CRYAA-Y118D mutant mouse.
The loach tribe Yunnanilini from China is reviewed using morphological characters and the complete mitochondrial genome of some selected species. Molecular data suggested that the tribe Yunnanilini is not monophyletic and divided into three clades. Species of the Y. nigromaculatus group form an independent genus and are placed in Eonemachilus. In the phylogenetic tree, Y. jinxiensis clustered with Paranemachilus genelepis, and Y. pulcherrimus clustered with Micronemacheilus cruciatus, indicating that Y. jinxiensis and Y. pulcherrimus belong to Paranemachilus and Micronemacheilus, respectively. Based on morphological data, four species from Guangxi, i.e., Y. bailianensis and Y. longibarbatus are placed in Heminoemacheilus, while Y. jinxiensis and Y. pulcherrimus, are placed in Paranemachilus, and in Micronemacheilus, respectively. Yunnanilus niulanensis and Y. qujinensis are treated as junior synonyms of Eonemachilus caohaiensis. The shared character of Eonemachilus, Micronemacheilus, and Yunnanilus is the short separation between the anterior and posterior nostrils. The genera can be distinguished from each other by mouth structure, characteristics of the lateral line and cephalic lateral-line canals, and papillae on the median part of both lips. The anterior and posterior nostrils of Heminoemacheilus and Paranemachilus are closely set. Characters distinguishing of Paranemachilus and Micronemacheilus are cheeks covered by scales and lips with papillae, respectively. Furthermore, our phylogenetic tree and morphological characters supported Traccatichthys as a valid genus, which can be distinguished from Micronemacheilus by anterior and posterior nostril closely set (vs. clearly separated). Four species are placed in Traccatichthys.