Identification and characterization of two long-type peptidoglycan recognition proteins, PGRP-L1 and PGRP-L2, in the orange-spotted grouper, Epinephelus coioides.

Peptidoglycan recognition proteins (PGRPs) play an important role in innate immunity by recognizing components of pathogenic bacteria (such as peptidoglycan, PGN) and are evolutionarily conserved pattern recognition receptors (PRRs) in both invertebrates and vertebrates. In the present study, two long-type PGRPs (designed as Eco-PGRP-L1 and Eco-PGRP-L2) were identified in orange-spotted grouper (Epinephelus coioides), which is a major economic species cultured in Asia. The predicted protein sequences of both Eco-PGRP-L1 and Eco-PGRP-L2 contain a typical PGRP domain. Eco-PGRP-L1 and Eco-PGRP-L2 exhibited organ/tissue-specific expression patterns. An abundant expression of Eco-PGRP-L1 was observed in pyloric caecum, stomach and gill, whereas a highest expression level of Eco-PGRP-L2 was found in head kidney, spleen, skin and heart. In addition, Eco-PGRP-L1 is distributed in the cytoplasm and nucleus, while Eco-PGRP-L2 is mainly localized in cytoplasm. Both Eco-PGRP-L1 and Eco-PGRP-L2 were induced following the stimulation of PGN and have PGN binding activity. In addition, functional analysis revealed that Eco-PGRP-L1 and Eco-PGRP-L2 possess antibacterial activity against Edwardsiella tarda. These results may contribute to understand the innate immune system of orange-spotted grouper.

Anti-Epstein-Barr Viral Agents from the Medicinal Herb-Derived Fungus Alternaria alstroemeriae Km2286.

Chromatographic separation on the liquid-state fermented products produced by the fungal strain Alternaria alstroemeriae Km2286 isolated from the littoral medicinal herb Atriplex maximowicziana Makino resulted in the isolation of compounds 1-9. Structures were determined by spectroscopic analysis as four undescribed perylenequinones, altertromins A-D (1-4), along with altertoxin IV (5), altertoxin VIII (6), stemphyperylenol (7), tenuazonic acid (8), and allo-tenuazonic acid (9). Compounds 1-6 exhibited antiviral activities against Epstein-Barr virus (EBV) with EC50 values ranging from 0.17 ± 0.07 to 3.13 ± 0.31 µM and selectivity indices higher than 10. In an anti-neuroinflammatory assay, compounds 1-4, 6, and 7 showed inhibitory activity of nitric oxide production in lipopolysaccharide-induced microglial BV-2 cells, with IC50 values ranging from 0.33 ± 0.04 to 4.08 ± 0.53 µM without significant cytotoxicity. This is the first report to describe perylenequinone-type compounds with potent anti-EBV and anti-neuroinflammatory activities.

Establishment of an astrocyte-like cell line from the brain of tilapia (Oreochromis niloticus) for virus pathogenesis and a vitro model of the blood-brain barrier.

A new cell line was established from the brain of a cultured fish, tilapia (Oreochromis niloticus), designated as TA-02 (Tilapia Astrocyte clone 02 cell line). The TA-02 cells are grown for 300 days in an L-15 medium supplemented with 10% fetal bovine serum (FBS). This cell line showed excellent proliferative capacity and expressed various neuroglial cell markers, including SOX2, SOX10, Hes1, Notch1, Occludin, E-cadherin, and GFAP. In addition, TA-02 cells were susceptible to Tilapia Lake Virus (TiLV) as demonstrated by the presence of a severe cytopathic effect (CPE), virus particle in a transmission electron microscope (TEM), and PCR positive signal. Bacterial cytotoxicity studies showed that Streptococcus agalactiae was toxic to TA-02 cells. When co-culture with trans-well, TA-02 exhibited prominent barrier properties, manifested by tight intercellular junctions and increased trans-endothelial electrical resistance (TEER). In addition, the barrier is effective against Escherichia coli (non-meningitis pathogenic bacteria). In contrast, S. agalactiae (meningitis pathogenic bacteria) can pass through the membrane comprising the cells in the trans-well insert. The newly established TA-02 cell line provided a valuable tool for virus pathogenesis and a vitro model of the fish blood-brain barrier.

Regulation of Epstein-Barr Virus Minor Capsid Protein BORF1 by TRIM5α.

TRIM5α is a host anti-retroviral restriction factor that destroys human immunodeficiency virus (HIV) virions and triggers innate immune signaling. TRIM5α also mediates the autophagic degradation of target proteins via TRIMosome formation. We previously showed that TRIM5α promotes Epstein-Barr virus (EBV) Rta ubiquitination and attenuates EBV lytic progression. In this study, we sought to elucidate whether TRIM5α can interact with and induce the degradation of EBV capsid proteins. Glutathione S-transferase (GST) pulldown and immunoprecipitation assays were conducted to identify interacting proteins, and mutants were generated to investigate key binding domains and ubiquitination sites. Results showed that TRIM5α binds directly with BORF1, an EBV capsid protein with a nuclear localization signal (NLS) that enables the transport of EBV capsid proteins into the host nucleus to facilitate capsid assembly. TRIM5α promotes BORF1 ubiquitination, which requires the surface patch region in the TRIM5α PRY/SPRY domain. TRIM5α expression also decreases the stability of BORF1(6KR), a mutant with all lysine residues mutated to arginine. However, chloroquine treatment restores the stability of BORF1(6KR), suggesting that TRIM5α destabilizes BORF1 via direct recognition of its substrate for autophagic degradation. These results reveal novel insights into the antiviral impact of TRIM5α beyond retroviruses.

Molecular cloning, characterization and expression profiles of CD2AP in Nile tilapia (Oreochromis niloticus) responding to Streptococcus agalactiae infection and interaction with CD2 cytoplasmic segment.

The interaction between CD2-associated protein (CD2AP) and CD2 plays a vital role in lymphocyte adhesion and T cells activation in mammals. In this study, a CD2AP gene (GenBank accession number: MK579862; designated as On-CD2AP) was identified from tilapia (Oreochromis niloticus). Sequence analysis showed that On-CD2AP protein shares high similarity with mammals, including three Src homology 3 (SH3) domains, a section of poly proline motif and a coiled coil region. Transcription levels of On-CD2AP were detected in nine tissues of healthy Nile tilapia, and the highest expression levels were detected in the spleen and gill. On-CD2AP were significantly up-regulated in thymus, head kidney and brain after infected by Streptococcus agalactiae, as well as in head kidney leukocytes (HKLs) with LPS and LTA stimulation. Moreover, a section conserved pro-rich motif that are responsible for binding of CD2 to CD2AP were found in the CD2 cytoplasmic sequence of Nile tilapia (On-CD2C). A weak interaction between On-CD2AP and On-CD2C was proved by yeast two-hybrid assay. In addition, the recombinant proteins of CD2AP-His (rOn-CD2AP-His) and GST-CD2C (GST-rOn-CD2C) were obtained through prokaryotic expression system. His pull-down assay showed that rOn-CD2AP-His and GST-rOn-CD2C could bind to each other. These findings indicate that CD2AP is crucial in immune response during S.agalactiae infection, and the mechanism of interaction between CD2AP and CD2 is conservative in Nile tilapia.

Identification of virion-associated transcriptional transactivator (VATT) of SGIV ICP46 promoter and their binding site on promoter.

BACKGROUND: Iridoviruses are large DNA viruses that cause diseases in fish, amphibians and insects. Singapore grouper iridovirus (SGIV) is isolated from cultured grouper and characterized as a ranavirus. ICP46 is defined to be a core gene of the family Iridoviridae and SGIV ICP46 was demonstrated to be an immediate-early (IE) gene associated with cell growth control and could contribute to virus replication in previous research. METHODS: The transcription start site (TSS) and 5'-untranslated region (5'-UTR) of SGIV ICP46 were determined using 5' RACE. The core promoter elements of ICP46s were analyzed by bioinformatics analysis. The core promoter region and the regulation model of SGIV ICP46 promoter were revealed by the construction of serially deleted promoter plasmids, transfections, drug treat and luciferase reporter assays. The identification of virion-associated transcriptional transactivator (VATT) that interact with SGIV ICP46 promoter and their binding site on promoter were performed by electrophoretic mobility shift assays (EMSA), DNA pull-down assays and mass spectrometry (MS). RESULTS: SGIV ICP46 was found to have short 5'-UTR and a presumptive downstream promoter element (DPE), AGACA, which locates at + 36 to + 39 nt downstream of the TSS. The core promoter region of SGIV ICP46 located from - 22 to + 42 nt relative to the TSS. VATTs were involved in the promoter activation of SGIV ICP46 and further identified to be VP12, VP39, VP57 and MCP. A 10-base DNA sequence "ATGGCTTTCG" between the TSS and presumptive DPE was determined to be the binding site of the VATTs. CONCLUSION: Our study showed that four VAATs (VP12, VP39, VP57 and MCP) might bind with the SGIV ICP46 promoter and be involved in the promoter activation. Further, the binding site of the VATTs on promoter was a 10-base DNA sequence between the TSS and presumptive DPE.

Molecular Cloning and Expression Analysis of IgD in Nile Tilapia (Oreochromis niloticus) in Response to Streptococcus agalactiae Stimulus.

IgD is considered to be a recently-evolved Ig and a puzzling molecule, being previously found in all vertebrate taxa, except for birds. Although IgD likely plays an important role in vertebrate immune responses, the function of IgD in Nile tilapia (Oreochromis niloticus) is virtually unknown. In the present study, a membrane form of IgD (mIgD) heavy chains were cloned from the GIFT strain of Nile tilapia (designated On-mIgD). The On-mIgD heavy chain's cDNA is composed of 3347 bp with a 31 bp of 5'-UTR, 3015 bp open reading frame (ORF) and 301 bp 3'-UTR, encoding a polypeptide of 1004 amino acids (GenBank accession no: KF530821). Phylogenetic analysis revealed that On-mIgD heavy chains showed the highest similarity to Siniperca chuatsi. Quantitative real-time PCR (qRT-PCR) analysis showed that On-mIgD expression occurred predominately in head kidney, thymus, spleen, and kidney. After Streptococcus agalactiae infection, transcripts of On-mIgD increased and reached its peak at 48 h in the head kidney and thymus, and 72 h in the spleen, respectively. Taken together, these results collectively indicated that IgD could possibly have a key role to play in the immune response when bacterial infections in Nile tilapia.

Activation of the ubiquitin proteasome pathway by silk fibroin modified chitosan nanoparticles in hepatic cancer cells.

Silk fibroin (SF) is a protein with bulky hydrophobic domains and can be easily purified as sericin-free silk-based biomaterial. Silk fibroin modified chitosan nanoparticle (SF-CSNP), a biocompatible material, has been widely used as a potential drug delivery system. Our current investigation studied the bio-effects of the SF-CSNP uptake by liver cells. In this experiment, the characterizations of SF-CSNPs were measured by particle size analysis and protein assay. The average size of the SF-CSNP was 311.9 ± 10.7 nm, and the average zeta potential was +13.33 ± 0.3 mV. The SF coating on the SF-CSNP was 6.27 ± 0.17 µg/mL. Moreover, using proteomic approaches, several proteins involved in the ubiquitin proteasome pathway were identified by analysis of differential protein expressions of HepG2 cell uptake the SF-CSNP. Our experimental results have demonstrated that the SF-CSNP may be involved in liver cancer cell survival and proliferation.

Chemical constituents from a marine medicinal brown alga-derived Xylaria acuta SC1019.

In this study, a marine medicinal brown alga Sargassum cristaefolium-derived fungal strain Xylaria acuta SC1019 was isolated and identified. Column chromatography of the extracts from liquid- and solid-fermented products of the fungal strain was carried out, and led to the isolation of twenty-one compounds. Their structures were characterized by spectroscopic analysis, and the absolute configurations were further established by single X-ray diffraction analysis or modified Mosher's method as nine previously undescribed compounds, namely xylarilactones A-C (1-3), ent-gedebic acid 8-O-α-D-glucopyranoside (4), 5R-hydroxylmethylmellein 11-O-α-D-glucopyranoside (5), ent-hymatoxin E 16-O-α-D-mannopyranoside (6), 19,20-epoxycytochalasin S (7), 19,20-epoxycytochalasin T (8), and (2R)-butylitaconic acid (9), along with twelve known compounds 10-21. All the isolates were subjected to anti-inflammatory and anti-angiogenic assays. Compounds 1, 5, 7, 10, and 17 showed moderate nitric oxide production inhibitory activities in lipopolysaccharide-activated BV-2 microglial cells with IC50 values of 19.55 ± 0.35, 16.10 ± 0.57, 15.20 ± 0.87, 11.76 ± 0.49, and 11.30 ± 0.32 µM, respectively, as compared to curcumin (IC50 = 2.69 ± 0.34 µM) without any significant cytotoxicity. Compounds 7, 8, and 21 displayed potent anti-angiogenic activities by suppressing the growth of human endothelial progenitor cells with IC50 values of 0.44 ± 0.01, 0.47 ± 0.03, and 0.53 ± 0.01 µM, respectively, as compared to sorafenib (IC50 = 5.50 ± 1.50 µM).

Expression and immunogenicity analysis of accessory colonization factor A from Vibrio alginolyticus strain HY9901.

The accessory colonization factor A (ACFA) of Vibrio alginolyticus plays an important role in the efficient colonization of the bacterium and is potential candidates for vaccine development. In present study, the acfA gene was cloned, expressed and purified. Western blot analysis revealed protein recognition with the native ACFA in different V. alginolyticus strains. To analyze the immunogenicity of the recombinant ACFA, Lutjanus erythropterus Bloch were immunized by intraperitoneal injection, and the results demonstrated that the recombinant ACFA produced an observable antibody response in all sera of the vaccinated fish. The differential expressions of RAG1 gene in various tissues of L. erythropterus were analyzed by fluorescent quantitative real-time PCR, and the results showed the RAG1 mRNA expression was significantly up-regulated in thymus, head kidney and spleen tissue. Furthermore, the protective property of recombinant ACFA was evaluated through challenge with six heterogeneous virulent V. alginolyticus strains, and the immunohistochemical analysis in different tissues after challenge with V. alginolyticus. The results showed L. erythropterus vaccinated with recombinant ACFA were more tolerant of the infection by virulent V. alginolyticus strains. The data indicate that the recombinant ACFA could provide heterologous protection for the different virulent V. alginolyticus strains.

Molecular cloning and prokaryotic expression of vp5 gene of grass carp reovirus strain GCRV096.

VP5 is an outer capsid protein of grass carp reovirus (GCRV). It is predicted to involve in helping GCRV enter the host cells. In this study, the full-length vp5 gene (accession number in GenBank: JN206664.1) was cloned from GCRV strain GCRV096, which was isolated from diseased grass carp (Ctenopharyngodon idella) in southern China by RT-PCR technique using the primers designed from the known vp5 gene sequences of other strains of GCRV published in GenBank. The ORF sequence of vp5 is composed of 1,947 nucleotides encoding a 648-residues protein with a calculated molecular mass of 68.6 kDa and an estimated isoelectric point of 6.1. Sequence analysis results showed that VP5 might serve as a penetration protein and play an important role in GCRV penetration into the host cells. A full length of vp5 gene was subcloned into the prokaryotic expression vector pET-28a (+) and the recombinant plasmid (pET/GCRV-VP5) was then transduced into Escherichia coli BL21 (DE3) cells to express VP5 in vitro. SDS-PAGE and western blotting analysis indicated that the protein expressed successfully. Results also showed that the fusion protein expressed in the form of inclusion body, and it expressed in the highest level when induced with 0.2-mM IPTG at 28 °C for 4 h. These results are important for the future study on the molecular structure, function, and immunogenicity of GCRV capsid protein.

Protection against Vibrio alginolyticus in crimson snapper Lutjanus erythropterus immunized with a DNA vaccine containing the ompW gene.

The outer membrane proteins of Vibrio alginolyticus play an important role in the virulence of the bacterium and are potential candidates for vaccine development. In the present study, the ompW gene was cloned, expressed and purified. A DNA vaccine was constructed by inserting the ompW gene into a pcDNA plasmid. Crimson snapper Lutjanus erythropterus (Bloch) were injected intramuscularly with the recombinant plasmid pcDNA-ompW. The expression of the DNA vaccine was detected in gill, head kidney, heart, liver, spleen and injection site muscle of crimson snapper by RT-PCR 7 and 28 d post-vaccination. The ELISA results demonstrated that the DNA vaccine produced an observable antibody response in all sera of the vaccinated fish. In addition, crimson snapper immunized with the DNA vaccine showed a relative percentage survival (RPS) of 92.53%, indicating effective protection against V. alginolyticus infection.

Structural Insights into the Binding and Degradation Mechanisms of Protoporphyrin IX by the Translocator Protein TSPO.

The 18 kDa translocator protein (TSPO) has gained considerable attention as a clinical biomarker for neuroinflammation and a potential therapeutic target. However, the mechanisms by which TSPO associates with ligands, particularly the endogenous porphyrin ligand protoporphyrin IX (PpIX), remain poorly understood. In this study, we employed mutagenesis- and spectroscopy-based functional assays to investigate TSPO-mediated photo-oxidative degradation of PpIX and identify key residues involved in the reaction. We provide structural evidence using electron spin resonance, which sheds light on the highly conserved intracellular loop (LP1) connecting transmembrane 1 (TM1) and TM2. Our findings show that LP1 does not act as a lid to regulate ligand binding; instead, it interacts strongly with the TM3-TM4 linker (LP3) to stabilize the local structure of LP3. This LP1-LP3 interaction is crucial for maintaining the binding pocket structure, which is essential for proper ligand binding. Our results also demonstrate that PpIX accesses the pocket through the lipid bilayer without requiring conformational changes in TSPO. This study provides an improved understanding of TSPO-mediated PpIX degradation, highlighting potential therapeutic strategies to regulate the reaction.

Development of loop-mediated isothermal amplification method for rapid detection of Streptococcus iniae, the causative agent of streptococcicosis in fish.

Streptococcus iniae is a major pathogen that causes sever economic losses in tilapia aquaculture. A set of four specific primers was designed by targeting lctO gene. With Bst DNA polymerase, the target DNA can be clearly amplified for 60 min at 64 °C in a simple water bath. The sensitivity of the LAMP assay for the detection of S. iniae is about 12.4 cells per reaction in both of pure cultures and added fish tissues cultures. LAMP products could be judged with agar gel or naked eye after addition of SYBR Green I. There were no cross-reactions with other bacterial strains indicating high specificity of the LAMP. The LAMP method was also applied to detect S. iniae-infected tilapia tissues effectively. The LAMP assay reported here indicates the potential usefulness of the technique as a valuable simple, rapid alternative procedure for the detection of S. iniae during streptococcicosis monitoring of cultured fish.

Characterization of pathogenic Aeromonas veronii bv. veronii associated with ulcerative syndrome from chinese longsnout catfish (Leiocassis longirostris Günther).

273 bacterial strains were isolated from 20 Chinese longsnout catfish samples. The biochemical characteristics of all strains conformed to the species description of Aeromonas veronii bv. veronii on the basis of Vitek GNI+ card. Furthermore, 16S rDNA, gyrB and rpoD sequences of the representative strain PY50 were sequenced and showed high similarity with A. veronii bv. veronii in Genbank. Antibiotic-resistance of the representative strain PY50 was assessed by the Kirby-Bauer disk diffusion method, and the results showed it was susceptible and moderately susceptible to 13 and 4 of the 21 antimicrobial agents tested. Extracellular products of strain PY50 contained gelatinase, lecithinase, elastase, most of lipase and lipopolysaccharide. Virulence of strain PY50 and extracellular products to Chinese longsnout catfish were also tested, and LD50 were about 3.47×10(4) CFU per fish and 11.22 µg per fish in intraperitoneal injection respectively. This is the first report that A. veronii bv. veronii was the pathogenic agent of ulcerative syndrome in Chinese longsnout catfish.

Utilizing Proteomic Approach to Analyze Potential Antioxidant Proteins in Plant against Irradiation.

Gamma-ray irradiation is an effective and clean method of sterilization by inactivating microorganisms. It can also be applied to induce anti-oxidants for future application. In this study, the mung bean (Vigna radiata) was exposed to gamma-ray irradiation under the dose of 0, 5 or 10 kGy. With increasing irradiation doses, the concentrations of malondiadehyde decreased while the levels of total flavonoids and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity increased. It has been shown that consuming flavonoids can provide protective effects. In addition, proteomic analysis identified several proteins having anti-oxidant activities in the 5 kGy irradiated group. These proteins are Apocytochrome f, Systemin receptor SR 160, DELLA protein DWARF8, DEAD-box ATP-dependent RNA helicase 9, ζ-carotene desaturase (ZDS), and Floral homeotic protein AGAMOUS. Our findings indicate that plants contain a variety of phytochemicals and antioxidant proteins which may effectively prevent oxidative stress caused by irradiated peroxidation.

Analysis of the genetic diversity of the lymphocystis virus and its evolutionary relationship with its hosts.

Lymphocystis disease virus (LCDV) is the causative agent of lymphocystis disease. In this study, the mcp gene of LCDV and the cyt b gene of the host fish were selected as molecular markers, and the phylogenetic relationships between LCDV and its host were analyzed. The 25 LCDV isolates examined in this study were attributed to seven LCDV genotypes: genotype I (LCDV-1), genotype II (LCDV-cn, etc.), genotype III (LCDV-rf), genotype IV (LCDV-rc and LCDV-sb), genotype V (LCDV-cb), genotype VI (LCDV-tl), and genotype VII (LCDV-sa). Genotype VII is a new genotype. LCDV1 was found to have differentiated first, followed by LCDV-rf; then LCDV-tl; LCDV-cb; and then LCDV-sa; and by LCDV-rc and LCDV-sb; and finally by LCDV-cn, LCDV-C, and LCDV-jf. From the host evolutionary perspective, Rachycentron canadum was found to have differentiated first, followed by Trichogaster leeri, Chanda baculis, and Sebastes schlegeli, Lateolabrax sp., Sparus aurata, Platichthys flesus, and Paralichthys olivaceus. Comparison of the phylogenies of the host fish species and LCDVs revealed no significant evidence of cospeciation between LCDVs and their host fish. In-depth studies of the genetic variation in LCDVs can enhance our understanding of the mechanism of LCDV infection, which may provide important insights into the prevention and treatment of lymphocystis disease.

Targeting S1PR1 May Result in Enhanced Migration of Cancer Cells in Bladder Carcinoma.

Clinical bladder tumor histological analysis shows that high expression of S1PR1 is associated with poor patient prognosis. However, there are no studies that describe the underlying mechanism. To investigate the relative distribution and actual function of S1PR1 in bladder tumors, we analyzed multiple clinical databases in combination with tumor purity and immune cell infiltration simulations, as well as databases of well-defined histological phenotypes of bladder cancer, and single-cell sequencing of adjacent normal tissues and bladder tumors, and further compared them with bladder cancer cell lines. The results showed that S1PR1 expression was generally higher in normal tissues than in bladder cancer tissues, and its distribution was mainly in endothelial cells or immune cells. The association between high S1PR1 expression and poor prognosis may be due to tumor invasion of adjacent normal tissues, where highly expressed S1PR1 may affect prognostic interpretation. The effect of S1PR1 itself on cancer cells was associated with cell adhesion, and in bladder cancer cells, S1PR1 expression was negatively correlated with cell motility. Moreover, the use of FTY-720 will cause an increased metastatic ability of bladder cancer cells. In conclusion, we suggest that the use of S1PR1-specific inhibition as a synergistic treatment requires more observation and consideration.

Immune response in Lutjanus erythropterus induced by the major outer membrane protein (OmpU) of Vibrio alginolyticus.

The outer membrane proteins (OMPs) of the marine aquatic animal pathogen Vibrio alginolyticus play an important role in the virulence of the bacterium and are potential candidates for vaccine development. In this study, the major 35.6 kDa OMP of V. alginolyticus was isolated by gel excision from the crude OMP fraction from V. alginolyticus. The sequence of the first 27 amino acid residues from the N-terminal end of the protein is ATV YKD GGT ELL VGG RVE FRG DFI GSD, which has high homology with OmpU proteins from other Vibrio spp. (92%). Lutjanus erythropterus were vaccinated with OmpU, and immunogenicity was confirmed by subsequent western blotting. Enzyme-linked immunosorbent assay (ELISA) analysis demonstrated that OmpU produced an observable antibody response in all sera of the vaccinated fish. L. erythropterus vaccinated with OmpU produced specific antibodies, and were highly resistant to infection with virulent V. alginolyticus. These results indicate that OmpU is an effective vaccine candidate against V. alginolyticus for L. erythropterus.

The complete mitochondrial genome of a parasitic flatworm Senga ophiocephalina (Cestoda: Bothriocephalidae).

Mitochondrial DNA of nematodes undergoes frequent rearrangements, so it is a very good model for studying the mitochondrial genome evolution. The complete mitochondrial genome of a parasitic nematode Senga ophiocephalina was sequenced and annotated. The 13,816 bp-long genome contained 12 protein-coding genes (atp8 gene was missing), two ribosomal RNAs, 22 transfer RNAs, and a 391 bp non-coding region. Phylogenetic analysis showed that S. ophiocephalina forms a monophyletic cluster with the remaining two Bothriocephalidae species.