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Distinct evolution of toll‑like receptor signaling pathway genes in cetaceans
Ran Tian,Inge Seim,Zepeng Zhang,Ying Yang,Wenhua Ren,Shixia Xu,Guang Yang 한국유전학회 2019 Genes & Genomics Vol.41 No.12
Background The relatively rapid spread and diversity of marine pathogens posed an initial and ongoing challenge for cetaceans (whales, dolphins, and porpoises), descendants of terrestrial mammals that transitioned from land to sea approximately 56 million years ago. Toll-like receptors (TLRs) play important roles in regulating immunity against pathogen infections by detecting specific molecular patterns and activating a wide range of downstream signaling pathways. The ever-increasing catalogue of mammalian genomes offers unprecedented opportunities to reveal genetic changes associated with evolutionary and ecological processes. Objective This study aimed to explore the molecular evolution of TLR signaling pathway genes in cetaceans. Methods Genes involved in the TLR signaling pathway were retrieved by BLAST searches using human coding sequences as queries. We tested each gene for positive selection along the cetacean branches using PAML and Hyphy. Physicochemical property changes of amino acids at all positively selected residues were assessed by TreeSAAP and visualized with WebLogo. Bovine and dolphin TLR4 was assessed using human embryonic kidney cell line HEK293, which lacks TLR4 and its co-receptor MD-2. Results We demonstrate that eight TLR signaling pathway genes are under positive selection in cetaceans. These include key genes in the response to Gram-negative bacteria: TLR4, CD14, and LY96 (MD-2). Moreover, 41 out of 65 positively selected sites were inferred to harbor substitution that dramatically changes the physicochemical properties of amino acids, with most of them situated in or adjacent to functional regions. We also found strong evidence that positive selection occurred in the lineage of the Yangtze finless porpoise, likely reflecting relatively recent adaptions to a freshwater milieu. Species-specific differences in TLR4 response were observed between cetacean and terrestrial species. Cetacean TLR4 was significantly less responsive to lipopolysaccharides from a terrestrial E. coli strain, possibly a reflection of the arms race of host–pathogen co-evolution faced by cetaceans in an aquatic environment. Conclusion This study provides further impetus for studies on the evolution and function of the cetacean immune system.
( Sheng Nan Li ),( Dao Sen Guo ),( Bo Guang Zhao ),( Jian Ling Ye ),( Jie Tian ),( Wen Qing Ren ),( Yun Wei Ju ),( Peng Cui ),( Rong Gui Li ) 한국미생물 · 생명공학회 2010 Journal of microbiology and biotechnology Vol.20 No.8
A cDNA encoding a cysteine protease inhibitor (CPI) was isolated from the cDNA library of clamworm Perinereis aibuhitensis Grube. The deduced amino acid sequence analysis showed that the protein had 51%, 48%, and 48% identity with Zgc: 153129 from Danio rerio, cystatin B from Theromyzon tessulatum, and the ChainA, stefin B tetramer from Homo sapiens, respectively. The gene was cloned into the intracellular expression vector pET-15b and expressed in Escherichia coli. The recombinant CPI (PA-CPI) was purified by affinity chromatography on Nicharged resin and ion-exchange chromatography on DEAE-Sepharose FF. The relative molecular mass of PACPI was 16 kDa as deduced by SDS-PAGE. Activity analysis showed that the recombinant protein could inhibit the proteolytic activity of papain. A constitutive and secretive expression vector was also constructed, and the cDNA encoding CPI was subcloned into the vector for extracellular expression. Western blotting analysis results showed that the PA-CPI was secreted into the medium. Bioassay demonstrated that E. coli DH5α harboring pUC18ompAcat-CPI showed a significant difference in mortality to the Asian longhorned beetle Anoplophora glabripennis compared with untransformed E. coli DH5α and control.
Yan-Ling Chen,Xian-Guo Guo,Wen-Yu Song,Tian-Guang Ren,Lei Zhang,Rong Fan,Cheng-Fu Zhao,Zhi-Wei Zhang,Wenge Dong,Xiao-Bin Huang,Dao-chao Jin 대한기생충학ㆍ열대의학회 2023 The Korean Journal of Parasitology Vol.61 No.3
Chigger mites are the vector of scrub typhus. This study estimates the infestation status and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019. Chiggers were identified under the microscope, and infestation indices were calculated. The Preston’s log-normal model was used to fit the curve of species abundance distribution. A total of 6,557 chiggers were collected in 136 of 342 N. fulvescens rats, showing high overall infestation indices (prevalence=39.8%, mean abundance=19.2, mean intensity=48.2) and high species diversity (S =100, H’=3.0). Leptotrombidium cangjiangense, Neotrombicula japonica, and Ascoschoengastia sifanga were the three dominant chigger species (constituent ratio=42.9%; 2,736/6,384) and exhibited an aggregated distribution among different rat individuals. We identified 100 chigger species, with 3 of them (Leptotrombidium scutellare, Leptotrombidium wenense, and Leptotrombidium deliense) as the main vectors of scrub typhus in China and nine species as potential vectors of this disease. Disease vector occurrence on N. fulvescens may increase the risk of spreading scrub typhus from rats to humans. Chigger infestation on N. fulvescens varied significantly in different environments. The species abundance distribution showed a log-normal distribution pattern. The estimated number of chigger species on N. fulvescens was 126 species.