The complete mitochondrial genomes for three Toxocara species of human and animal health significance

<p>Abstract</p> <p>Background</p> <p>Studying mitochondrial (mt) genomics has important implications for various fundamental areas, including mt biochemistry, physiology and molecular biology. In addition, mt genome sequences have provided useful markers for investigating population genetic structures, systematics and phylogenetics of organisms. <it>Toxocara canis, Toxocara cati </it>and <it>Toxocara malaysiensis </it>cause significant health problems in animals and humans. Although they are of importance in human and animal health, no information on the mt genomes for any of <it>Toxocara </it>species is available.</p> <p>Results</p> <p>The sizes of the entire mt genome are 14,322 bp for <it>T. canis</it>, 14029 bp for <it>T. cati </it>and 14266 bp for <it>T. malaysiensis</it>, respectively. These circular genomes are amongst the largest reported to date for all secernentean nematodes. Their relatively large sizes relate mainly to an increased length in the AT-rich region. The mt genomes of the three <it>Toxocara </it>species all encode 12 proteins, two ribosomal RNAs and 22 transfer RNA genes, but lack the ATP synthetase subunit 8 gene, which is consistent with all other species of Nematode studied to date, with the exception of <it>Trichinella spiralis</it>. All genes are transcribed in the same direction and have a nucleotide composition high in A and T, but low in G and C. The contents of A+T of the complete genomes are 68.57% for <it>T. canis</it>, 69.95% for <it>T. cati </it>and 68.86% for <it>T. malaysiensis</it>, among which the A+T for <it>T. canis </it>is the lowest among all nematodes studied to date. The AT bias had a significant effect on both the codon usage pattern and amino acid composition of proteins. The mt genome structures for three <it>Toxocara </it>species, including genes and non-coding regions, are in the same order as for <it>Ascaris suum </it>and <it>Anisakis simplex</it>, but differ from <it>Ancylostoma duodenale</it>, <it>Necator americanus </it>and <it>Caenorhabditis elegans </it>only in the location of the AT-rich region, whereas there are substantial differences when compared with <it>Onchocerca volvulus</it>,<it>Dirofiliria immitis </it>and <it>Strongyloides stercoralis</it>. Phylogenetic analyses based on concatenated amino acid sequences of 12 protein-coding genes revealed that the newly described species <it>T. malaysiensis </it>was more closely related to <it>T. cati </it>than to <it>T. canis</it>, consistent with results of a previous study using sequences of nuclear internal transcribed spacers as genetic markers.</p> <p>Conclusion</p> <p>The present study determined the complete mt genome sequences for three roundworms of human and animal health significance, which provides mtDNA evidence for the validity of <it>T. malaysiensis </it>and also provides a foundation for studying the systematics, population genetics and ecology of these and other nematodes of socio-economic importance.</p

Identification and characterization of microRNAs in Clonorchis sinensis of human health significance

<p>Abstract</p> <p>Background</p> <p><it>Clonorchis sinensis </it>is a zoonotic parasite causing clonorchiasis-associated human disease such as biliary calculi, cholecystitis, liver cirrhosis, and it is currently classified as carcinogenic to humans for cholangiocarcinoma. MicroRNAs (miRNAs) are non-coding, regulating small RNA molecules which are essential for the complex life cycles of parasites and are involved in parasitic infections. To identify and characterize miRNAs expressed in adult <it>C. sinensis </it>residing chronically in the biliary tract, we developed an integrative approach combining deep sequencing and bioinformatic predictions with stem-loop real-time PCR analysis.</p> <p>Results</p> <p>Here we report the use of this approach to identify and clone 6 new and 62,512 conserved <it>C. sinensis </it>miRNAs which belonged to 284 families. There was strong bias on families, family members and sequence nucleotides in <it>C. sinensis</it>. Uracil was the dominant nucleotide, particularly at positions 1, 14 and 22, which were located approximately at the beginning, middle and end of conserved miRNAs. There was no significant "seed region" at the first and ninth positions which were commonly found in human, animals and plants. Categorization of conserved miRNAs indicated that miRNAs of <it>C. sinensis </it>were still innovated and concentrated along three branches of the phylogenetic tree leading to bilaterians, insects and coelomates. There were two miRNA strategies in <it>C. sinensis </it>for its parasitic life: keeping a large category of miRNA families of different animals and keeping stringent conserved seed regions with high active innovation in other places of miRNAs mainly in the middle and the end, which were perfect for the parasite to perform its complex life style and for host changes.</p> <p>Conclusions</p> <p>The present study represented the first large scale characterization of <it>C. sinensis </it>miRNAs, which have implications for understanding the complex biology of this zoonotic parasite, as well as miRNA studies of other related species such as <it>Opisthorchis viverrini </it>and <it>Opisthorchis felineus </it>of human and animal health significance.</p

Prevalence of Sarcoptes scabiei

Little is known about the prevalence of Sarcoptes scabiei infection in pet dogs in China. In the present study, the prevalence of S. scabiei infection in pet dogs in Guangzhou, southern China, was investigated between January and December, 2009. A total of 3,977 pet dogs admitted to animal hospitals were examined for the presence of S. scabiei using a parasitological approach. The average prevalence of S. scabiei infection in pet dogs is 1.18% (95% confidence interval (CI): 0.85–1.52%). The prevalence of S. scabiei was higher in winter (1.42%; 95% CI: 0.29–2.55%), summer (1.39%; 95% CI: 0.83–1.96%), and autumn (1.1%; 95% CI: 0.53–1.68%) than in spring (0.63%; 95% CI: 0.02–1.25%). Furthermore, the prevalence of S. scabiei was the highest in Pekingese (21.88%; 95% CI: 7.55–36.2%), followed by Papillon (5.26%; 95% CI: 0–11.06%) and Bichon Frise (3.19%; 95% CI: 0–6.75%). The results of the present investigation indicate that S. scabiei infection is prevalent in pet dogs in Guangzhou, China, which provides relevant “baseline” data for conducting control strategies and measures against scabies in this region and elsewhere in China. To our knowledge, this is the first comprehensive report of S. scabiei prevalence in pet dogs in China

Prevalence of Clonorchis sinensis infection in dogs and cats in subtropical southern China

<p>Abstract</p> <p>Background</p> <p>Clonorchiasis, caused by <it>Clonorchis sinensis</it>, is one of the major parasitic zoonoses in China, particularly in China's southern Guangdong province where the prevalence of <it>C. sinensis </it>infection in humans is high. However, little is known of the prevalence of <it>C. sinensis </it>infection in its reservoir hosts dogs and cats. Hence, the prevalence of <it>C. sinensis </it>infection in dogs and cats was investigated in Guangdong province, China between October 2006 and March 2008.</p> <p>Results</p> <p>A total of 503 dogs and 194 cats from 13 administrative regions in Guangdong province were examined by post-mortem examination. The worms were examined, counted, and identified to species according to existing keys and descriptions. The average prevalences of <it>C. sinensis </it>infection in dogs and cats were 20.5% and 41.8%, respectively. The infection intensities in dogs were usually light, but in cats the infection intensities were more serious. The prevalences were higher in some of the cities located in the Pearl River Delta region which is the most important endemic area in Guangdong province, but the prevalences were relatively lower in seaside cities.</p> <p>Conclusions</p> <p>The present investigation revealed a high prevalence of <it>C. sinensis </it>infection in its reservoir hosts dogs and cats in China's subtropical Guangdong province, which provides relevant "base-line" data for conducting control strategies and measures against clonorchiasis in this region.</p

NCAM regulates temporal specification of neural progenitor cells via profilin2 during corticogenesis

The development of cerebral cortex requires spatially and temporally orchestrated proliferation, migration, and differentiation of neural progenitor cells (NPCs). The molecular mechanisms underlying cortical development are, however, not fully understood. The neural cell adhesion molecule (NCAM) has been suggested to play a role in corticogenesis. Here we show that NCAM is dynamically expressed in the developing cortex. NCAM expression in NPCs is highest in the neurogenic period and declines during the gliogenic period. In mice bearing an NPC-specific NCAM deletion, proliferation of NPCs is reduced, and production of cortical neurons is delayed, while formation of cortical glia is advanced. Mechanistically, NCAM enhances actin polymerization in NPCs by interacting with actin-associated protein profilin2. NCAM-dependent regulation of NPCs is blocked by mutations in the profilin2 binding site. Thus, NCAM plays an essential role in NPC proliferation and fate decision during cortical development by regulating profilin2-dependent actin polymerization

Suppression of Allograft Rejection by Tim-1-Fc through Cross-Linking with a Novel Tim-1 Binding Partner on T Cells

Engagement of T-cell immunoglobulin mucin (Tim)-1 on T cells with its ligand, Tim-4, on antigen presenting cells delivers positive costimulatory signals to T cells. However, the molecular mechanisms for Tim-1-mediated regulation of T-cell activation and differentiation are relatively poorly understood. Here we investigated the role of Tim-1 in T-cell responses and allograft rejection using recombinant human Tim-1 extracellular domain and IgG1-Fc fusion proteins (Tim-1-Fc). In vitro assays confirmed that Tim-1-Fc selectively binds to CD4+ effector T cells, but not dendritic cells or natural regulatory T cells (nTregs). Tim-1-Fc was able to inhibit the responses of purified CD4+ T cells that do not express Tim-4 to stimulation by anti-CD3/CD28 mAbs, and this inhibition was associated with reduced AKT and ERK1/2 phosphorylation, but it had no influence on nTregs. Moreover, Tim-1-Fc inhibited the proliferation of CD4+ T cells stimulated by allogeneic dendritic cells. Treatment of recipient mice with Tim-1-Fc significantly prolonged cardiac allograft survival in a fully MHC-mismatched strain combination, which was associated with impaired Th1 response and preserved Th2 and nTregs function. Importantly, the frequency of Foxp3+ cells in splenic CD4+ T cells was increased, thus shifting the balance toward regulators, even though Tim-1-Fc did not induce Foxp3 expression in CD4+CD25− T cells directly. These results indicate that Tim-1-Fc can inhibit T-cell responses through an unknown Tim-1 binding partner on T cells, and it is a promising immunosuppressive agent for preventing allograft rejection