The outer membrane protein Tp92 of Treponema pallidum delays human neutrophil apoptosis via the ERK, PI3K/Akt, and NF-κB pathways.

Syphilis is a persistent sexually transmitted disease caused by infiltration of the elusive pathogen Treponema pallidum. Despite the prevalence of human polymorphonuclear neutrophils (hPMNs) within cutaneous lesions, which are characteristic of incipient syphilis, their role in T. pallidum infection remains unclear. Tp92 is the only T. pallidum helical outer membrane protein that exhibits structural features similar to those of outer membrane proteins in other gram-negative bacteria. However, the functional mechanism of this protein in immune cells remains unclear. Neutrophils are short-lived cells that undergo innate apoptosis in response to external stimuli that typically influence this process. In this study, we determined that Tp92 impedes the activation of procaspase-3 via the ERK MAPK, PI3K/Akt, and NF-κB signaling pathways, consequently suppressing caspase-3 activity within hPMNs, and thereby preventing hPMNs apoptosis. Furthermore, Tp92 could also modulate hPMNs apoptosis by enhancing the expression of the anti-apoptotic protein Mcl-1, stimulating IL-8 secretion, and preserving the mitochondrial membrane potential. These findings provide valuable insights into the molecular mechanisms underlying T. pallidum infection and suggest potential therapeutic targets for syphilis treatment.

Treponema pallidum Tp0751 alters the expression of tight junction proteins by promoting bEnd3 cell apoptosis and IL-6 secretion.

BACKGROUND: Neurosyphilis is a serious complication caused by the invasion of the central nervous system by Treponema pallidum subsp. pallidum (T. pallidum). However, the molecular mechanism by which T. pallidum crosses the blood-brain barrier has not been fully elucidated. OBJECTIVES: The primary purpose of this experimental design was to explore the effect of the T. pallidum adhesion protein Tp0751 on the blood-brain barrier and cerebrovascular endothelial cells. METHODS: BEnd3 cells were used to construct a monolayer blood-brain barrier model in vitro. The integrity of blood-brain barrier model was evaluated by a transendothelial cell resistance meter and transmission electron microscope after the stimulation of recombinant protein TP0751. Hoechst 33258 staining and flow cytometry were used to detect the apoptosis rate. Western blotting assay was used to measure the expression of tight junction proteins and apoptosis-related proteins. The enzyme activity detection kit was responsible for detecting the enzyme activities of Caspase 3, Caspase 8 and Caspase 9. The expression of pro-inflammatory cytokines TNF-α, IL-1ß and IL-6 at the transcription and translation levels were detected by qRT-PCR and ELISA, respectively. RESULTS: The results showed that, the tight junction structures between cells showed no obvious fragmentation, but the levels of the tight junction proteins zonula occludens-1 and occludin were reduced by the effects of Tp0751 on bEnd3 cells. In addition, further research demonstrated that after incubation with bEnd3 cells, Tp0751 induced cell apoptosis in a concentration- and time-dependent manner via the caspase 8/caspase 3 pathway. These apoptotic processes may have contributed to the changes in tight junction proteins expression. Furthermore, the Tp0751 protein may be involved in the pathogenic process by which T. pallidum crosses the blood-brain barrier by promoting secretion of the proinflammatory factor interleukin-6. CONCLUSIONS: On the whole, this study is the first to reveal and highlight that Tp0751 may affect the expression of tight junction proteins by inducing apoptosis and promoting the secretion of the inflammatory cytokine IL-6, thus playing a role in the progression of neurosyphilis caused by T. pallidum.

Chlamydia psittaci inhibits apoptosis of human neutrophils by activating P2X7 receptor expression.

This study tested the hypothesis that Chlamydia psittaci (C. psittaci) survives and multiplies in human neutrophils by activating P2X7, a nonselective cationic channel receptor expressed constitutively on the surface of these cells. Findings illustrated that P2X7 receptor expression was enhanced in C. psittaci-infected neutrophils. C. psittaci was able to inhibite spontaneous apoptosis of neutrophils through mitochondrial-induced ATP release and IL-8 production. Importantly, inhibiting ATP activation of the P2X7 receptor with AZ10606120 promotes apoptosis, while stimulating P2X7 receptor expression with BzATP delayed spontaneous apoptosis of human neutrophils, suggesting that C. psittaci inhibits apoptosis of human neutrophils by activating P2X7 receptor. This study reveals new insights into the survival advantages of the latent persistent state of C. psittaci and the mechanism by which it evades the innate immune response.

PIWIL4 Maintains HIV-1 Latency by Enforcing Epigenetically Suppressive Modifications on the 5' Long Terminal Repeat.

Although substantial progress has been made in depicting the molecular pathogenesis of human immunodeficiency virus type 1 (HIV-1) infection, the comprehensive mechanism of HIV-1 latency and the most promising therapeutic strategies to effectively reactivate the HIV-1 latent reservoir to achieve a functional cure for AIDS remain to be systematically illuminated. Here, we demonstrated that piwi (P element-induced Wimpy)-like RNA-mediated gene silencing 4 (PIWIL4) played an important role in suppressing HIV-1 transcription and contributed to the latency state in HIV-1-infected cells through its recruitment of various suppressive factors, including heterochromatin protein 1α/ß/γ, SETDB1, and HDAC4. The knockdown of PIWIL4 enhanced HIV-1 transcription and reversed HIV-1 latency in both HIV-1 latently infected Jurkat T cells and primary CD4+ T lymphocytes and resting CD4+ T lymphocytes from HIV-1-infected individuals on suppressive combined antiretroviral therapy (cART). Furthermore, in the absence of PIWIL4, HIV-1 latently infected Jurkat T cells were more sensitive to reactivation with vorinostat (suberoylanilide hydroxamic acid, or SAHA), JQ1, or prostratin. These findings indicated that PIWIL4 promotes HIV-1 latency by imposing repressive marks at the HIV-1 5' long terminal repeat. Thus, the manipulation of PIWIL4 could be a novel strategy for developing promising latency-reversing agents (LRAs).IMPORTANCE HIV-1 latency is systematically modulated by host factors and viral proteins. During this process, the suppression of HIV-1 transcription plays an essential role in promoting HIV-1 latency. In this study, we found that PIWIL4 repressed HIV-1 promoter activity and maintained HIV-1 latency. In particular, we report that PIWIL4 can regulate gene expression through its association with the suppressive activity of HDAC4. Therefore, we have identified a new function for PIWIL4: it is not only a suppressor of endogenous retrotransposons but also plays an important role in inhibiting transcription and leading to latent infection of HIV-1, a well-known exogenous retrovirus. Our results also indicate a novel therapeutic target to reactivate the HIV-1 latent reservoir.

Adenosine deaminase acting on RNA-1 (ADAR1) inhibits hepatitis B virus (HBV) replication by enhancing microRNA-122 processing.

Adenosine deaminases acting on RNA-1 (ADAR1) involves adenosine to inosine RNA editing and microRNA processing. ADAR1 is known to be involved in the replication of various viruses, including hepatitis C and D. However, the role of ADAR1 in hepatitis B virus (HBV) infection has not yet been elucidated. Here, for the first time, we demonstrated ADAR1 antiviral activity against HBV. ADAR1 has two splicing isoforms in human hepatocytes: constitutive p110 protein and interferon-α (IFN-α)-responsive p150 protein. We found that overexpression of ADAR1 decreased HBV RNA in an HBV culture model. A catalytic-site mutant ADAR1 also decreased HBV RNA levels, whereas another adenosine deaminases that act on the RNA (ADAR) family protein, ADAR2, did not. Moreover, the induction of ADAR1 by stimulation with IFN-α also reduced HBV RNA levels. Decreases in endogenous ADAR1 expression by knock-down or knock-out increased HBV RNA levels. A major hepatocyte-specific microRNA, miRNA-122, was found to be positively correlated with ADAR1 expression, and exogenous miRNA-122 decreased both HBV RNA and DNA, whereas, conversely, transfection with a miRNA-122 inhibitor increased them. The reduction of HBV RNA by ADAR1 expression was abrogated by p53 knock-down, suggesting the involvement of p53 in the ADAR1-mediated reduction of HBV RNA. This study demonstrated, for the first time, that ADAR1 plays an antiviral role against HBV infection by increasing the level of miRNA-122 in hepatocytes.

Tim-3 blockade enhances the clearance of Chlamydia psittaci in the lung by promoting a cell-mediated immune response.

Chlamydia psittaci is remarkable at disrupting immunity and thus poses a great risk to the animal industry and public health. Immune inhibitory molecule upregulation and the accumulation of specialized cells play key roles in chlamydial clearance. It is clear that the T-cell immunoglobulin and mucin domain protein 3 receptor (Tim-3) can regulate effector T cells in infectious disease. However, the immunomodulatory effect of Tim-3 in C. psittaci infection remains unknown. Thus, the expression of Tim-3 in effector T cells and its immune regulatory function during C. psittaci infection were investigated. The level of Tim-3 on CD4+ and CD8+ T cells was meaningfully higher in C. psittaci-infected mice. Blockade of Tim-3 signaling by anti-Tim-3 antibody showed accelerated C. psittaci clearance and less pathological changes in the lung than isotype immunoglobulin treatment. Furthermore, treatment with anti-Tim-3 antibody greatly enhanced the levels of IFN-γ and interleukin (IL)-22/IL-17, which were correlated with an improved Th1- and Th17-mediated immune response, and decreased IL-10, which were related with a decreased Treg immune response. In conclusion, Tim-3 expression in effector T cells negatively regulates Th1 and Th17 immune responses against C. psittaci respiratory infection.

Chlamydia psittaci hypothetical inclusion membrane protein CPSIT_0842 evokes a pro-inflammatory response in monocytes via TLR2/TLR4 signaling pathways.

Chlamydia psittaci (C. psittaci) is an obligate intracellular pathogen that resides within a membrane-bound compartment known as the inclusion. Upon entering the host cell, Chlamydiae secrete numerous proteins to modify the inclusion membrane. Inclusion membrane (Inc) proteins are important pathogenic factors in Chlamydia and play crucial roles in the growth and development of Chlamydia. In the present study, the C. psittaci protein, CPSIT_0842, was identified and shown to localize to the inclusion membrane. Temporal analysis revealed that CPSIT_0842 is an early expression protein of Chlamydia. Moreover, this protein was shown to induce the expression of pro-inflammatory cytokines IL-6 and IL-8 in human monocytes (THP-1 cells) via the TLR2/TLR4 signaling pathway. CPSIT_0842 increases the expression of TLR2, TLR4, and adaptor MyD88. Suppression of TLR2, TLR4, and MyD88 markedly attenuated CPSIT_0842-induced production of IL-6 and IL-8. MAP kinases and NF-κB, important downstream molecules of TLR receptors in inflammatory signaling pathways, were also confirmed to be activated by CPSIT_0842. CPSIT_0842-induced production of IL-6 was reliant on activation of the ERK, p38, and NF-κB signaling pathways while IL-8 expression was regulated by the ERK, JNK, and NF-κB signaling pathways. Specific inhibitors of these signaling pathways significantly decreased CPSIT_0842-mediated expression of IL-6 and IL-8. Together these findings demonstrate that CPSIT_0842 upregulates the expression of IL-6 and IL-8 via TLR-2/TLR4-mediated MAPK and NF-κB signaling pathways in THP-1 cells. Exploring these molecular mechanisms enhances our understanding of C. psittaci pathogenesis.

STAG2 Regulates Homologous Recombination Repair and Sensitivity to ATM Inhibition.

Stromal antigen 2 (STAG2), a subunit of the cohesin complex, is recurrently mutated in various tumors. However, the role of STAG2 in DNA repair and its therapeutic implications are largely unknown. Here it is reported that knockout of STAG2 results in increased double-stranded breaks (DSBs) and chromosomal aberrations by reducing homologous recombination (HR) repair, and confers hypersensitivity to inhibitors of ataxia telangiectasia mutated (ATMi), Poly ADP Ribose Polymerase (PARPi), or the combination of both. Of note, the impaired HR by STAG2-deficiency is mainly attributed to the restored expression of KMT5A, which in turn methylates H4K20 (H4K20me0) to H4K20me1 and thereby decreases the recruitment of BRCA1-BARD1 to chromatin. Importantly, STAG2 expression correlates with poor prognosis of cancer patients. STAG2 is identified as an important regulator of HR and a potential therapeutic strategy for STAG2-mutant tumors is elucidated.

Treponema pallidum delays the apoptosis of human polymorphonuclear neutrophils through the intrinsic and extrinsic pathways.

Treponema pallidum is a "stealth pathogen" responsible for infectious sexually transmitted diseases. Although neutrophils are usually present in skin lesions of early syphilis, the role of these cells in T. pallidum infection has barely been investigated. Neutrophils are short-lived cells that undergo constitutive apoptosis, and phagocytosis usually accelerates this process. Here, we demonstrated that human polymorphonuclear neutrophils (hPMNs) could phagocytose T. pallidum in vitro. An unexpected discovery was that T. pallidum inhibited hPMNs apoptosis markedly in an opsonin-independent manner. Furthermore, this phenomenon was not affected by bacterial viability, as detected by annexin V, morphology studies, and TUNEL staining. Exploration of the underlying mechanism showed that expression of the cleaved forms of caspase-3, -8, and -9 and effector caspase activity were diminished significantly in T. pallidum-infected hPMNs. T. pallidum also impaired staurosporine- and anti-Fas-induced signaling for neutrophil apoptosis. Of note, these effects were accompanied by inducing the autocrine production of the anti-apoptotic cytokine IL-8. Taken together, our data revealed that T. pallidum could inhibit the apoptosis of hPMNs through intrinsic and extrinsic pathways and provide new insights for understanding the pathogenicity mechanisms of T. pallidum.

C-Reactive Protein Levels Predict Responses to PD-1 Inhibitors in Hepatocellular Carcinoma Patients.

Background: Serum C-reactive protein (CRP) is a biomarker of an acute inflammatory response and has been successfully used as a prognostic predictor for several malignancies. However, the clinicopathological significance of CRP levels in hepatocellular carcinoma (HCC) patients being treated with PD-1 inhibitors remains unclear. Methods: Serum CRP levels were measured for a total of 101 HCC patients that had been treated with PD-1 inhibitors from July 2018 to November 2019. The clinicopathological data was retrospectively analyzed to identify any clinical implications between CRP levels and responses to PD-1 inhibitors and patients' progression-free survival (PFS). Results: The median PFS was 8.87 months in the CRP-low subgroup and 3.67 months in the CRP-high subgroup (P = 0.009). Univariate and multivariate Cox regression analysis demonstrated that both serum CRP and AFP levels were independent risk factors for the PFS of HCC patients treated with PD-1 inhibitors (P < 0.05). Moreover, Cox regression analysis after Propensity Score Matching showed the similar results. A prognostic model combining CRP and AFP levels could significantly stratify HCC patients receiving PD-1 inhibitors into low-, intermediate-, and high-risk subgroups (P < 0.001). Patients in the risk subgroups reported similar overall response rates (P = 0.625) and significantly different disease control rates (low- vs. intermediate- vs. high-risk groups: 81.6% vs. 65.1% vs. 35%, respectively, P = 0.002). Conclusions: The results of this study support the association between high serum CRP levels with the response and PFS for HCC patients receiving PD-1 inhibitors. Furthermore, the levels of both CRP and AFP in an HCC patient before treatment initiation show great potential for determining the efficacy of PD-1 inhibitors.

The Chlamydia psittaci Inclusion Membrane Protein 0556 Inhibits Human Neutrophils Apoptosis Through PI3K/AKT and NF-κB Signaling Pathways.

Inclusion membrane proteins (Incs) play an important role in the structure and stability of chlamydial inclusion and the interaction between Chlamydia spp. and their hosts. Following Chlamydia infection through the respiratory tract, human polymorphonuclear neutrophils (hPMN) not only act as the primary immune cells reaching the lungs, but also serve as reservoir for Chlamydia. We have previously identified a Chlamydia psittaci hypothetical protein, CPSIT_0556, as a medium expressed inclusion membrane protein. However, the role of inclusion membrane protein, CPSIT_0556 in regulating hPMN functions remains unknown. In the present study, we found that CPSIT_0556 could not only inhibit hPMN apoptosis through the PI3K/Akt and NF-κB signaling pathways by releasing IL-8, but also delays procaspase-3 processing and inhibits caspase-3 activity in hPMN. Up-regulating the expression of anti-apoptotic protein Mcl-1 and down-regulating the expression of pro-apoptotic protein Bax could also inhibit the translocalization of Bax in the cytoplasm into the mitochondria, as well as induce the transfer of p65 NF-κB from the cytoplasm to the nucleus. Overall, our findings demonstrate that CPSIT_0556 could inhibit hPMN apoptosis through PI3K/Akt and NF-κB pathways and provide new insights towards understanding a better understanding of the molecular pathogenesis and immune escape mechanisms of C. psittaci.

Broadly neutralizing antibody-derived CAR T cells reduce viral reservoir in individuals infected with HIV-1.

BACKGROUNDChimeric antigen receptor (CAR) T cells have emerged as an approach to treat malignant tumors. This strategy has also been proposed for the treatment of HIV-1 infection. We have developed a broadly neutralizing antibody-derived (bNAb-derived) CAR T cell therapy that can exert specific cytotoxic activity against HIV-1-infected cells.METHODSWe conducted an open-label trial of the safety, side-effect profile, pharmacokinetic properties, and antiviral activity of bNAb-derived CAR T cell therapy in individuals infected with HIV-1 who were undergoing analytical interruption of antiretroviral therapy (ART).RESULTSA total of 14 participants completed only a single administration of bNAb-derived CAR T cells. CAR T cell therapy administration was safe and well tolerated. Six participants discontinued ART, and viremia rebound occurred in all of them, with a 5.3-week median time. Notably, the cell-associated viral RNA and intact proviruses decreased significantly after CAR T cell treatment. Analyses of HIV-1 variants before or after CAR T cell administration suggested that CAR T cells exerted pressure on rebound viruses, resulting in a selection of viruses with less diversity and mutations against CAR T cell-mediated cytotoxicity.CONCLUSIONNo safety concerns were identified with adoptive transfer of bNAb-derived CAR T cells. They reduced viral reservoir. All the rebounds were due to preexisting or emergence of viral escape mutations.TRIAL REGISTRATIONClinicalTrials.gov (NCT03240328).FUNDINGMinistry of Science and Technology of China, National Natural Science Foundation of China, and Department of Science and Technology of Guangdong Province.

In-Line Monitoring the Degradation of Polypropylene under Multiple Extrusions Based on Raman Spectroscopy.

Polymer degradation is a common problem in the extrusion process. In this work, Raman spectroscopy, a robust, rapid, and non-destructive tool for in-line monitoring, was utilized to in-line monitor the degradation of polypropylene (PP) under multiple extrusions. Raw spectra were pretreated by chemometrics methods to extract variations of spectra and eliminate noise. The variation of Raman intensity with the increasing number of extrusions was caused by the scission of PP chains and oxidative degradation, and the variation trend of Raman intensity indicated that long chains were more likely to be damaged by the extrusion. For the quantitative analysis of degradation, the partial least square was used to build a model to predict the degree of PP degradation measured by gel permeation chromatography (GPC). For the calibration set, the coefficient of determination (R2) and the root mean square error of cross-validation (RMSECV) were 0.9859 and 1.2676%, and for the prediction set, R2 and the root mean square error of prediction (RMSEP) were 0.9752 and 1.7228%, which demonstrated the accuracy of the proposed model. The in-line Raman spectroscopy combined with the chemometrics methods was proved to be an accurate and highly effective tool, which can monitor the degradation of polymer in real time.

Host factor SMYD3 is recruited by Ebola virus nucleoprotein to facilitate viral mRNA transcription.

The polymerase complex of Ebola virus (EBOV) is the functional unit for transcription and replication of viral genome. Nucleoprotein (NP) is a multifunctional protein with high RNA binding affinity and recruits other viral proteins to form functional polymerase complex. In our study, we investigated host proteins associated with EBOV polymerase complex using NP as bait in a transcription and replication competent minigenome system by mass spectrometry analysis and identified SET and MYND domain-containing protein 3 (SMYD3) as a novel host protein which was required for the replication of EBOV. SMYD3 specifically interacted with NP and was recruited to EBOV inclusion bodies through NP. The depletion of SMYD3 dramatically suppressed EBOV mRNA production. A mimic of non-phosphorylated VP30, which is a transcription activator, could partially rescue the viral mRNA production downregulated by the depletion of SMYD3. In addition, SMYD3 promoted NP-VP30 interaction in a dose-dependent manner. These results revealed that SMYD3 was a novel host factor recruited by NP to supporting EBOV mRNA transcription through increasing the binding of VP30 to NP. Thus, our study provided a new understanding of mechanism underlying the transcription of EBOV genome, and a novel anti-EBOV drug design strategy by targeting SMYD3.

TRIM28 promotes HIV-1 latency by SUMOylating CDK9 and inhibiting P-TEFb.

Comprehensively elucidating the molecular mechanisms of human immunodeficiency virus type 1 (HIV-1) latency is a priority to achieve a functional cure. As current 'shock' agents failed to efficiently reactivate the latent reservoir, it is important to discover new targets for developing more efficient latency-reversing agents (LRAs). Here, we found that TRIM28 potently suppresses HIV-1 expression by utilizing both SUMO E3 ligase activity and epigenetic adaptor function. Through global site-specific SUMO-MS study and serial SUMOylation assays, we identified that P-TEFb catalytic subunit CDK9 is significantly SUMOylated by TRIM28 with SUMO4. The Lys44, Lys56 and Lys68 residues on CDK9 are SUMOylated by TRIM28, which inhibits CDK9 kinase activity or prevents P-TEFb assembly by directly blocking the interaction between CDK9 and Cyclin T1, subsequently inhibits viral transcription and contributes to HIV-1 latency. The manipulation of TRIM28 and its consequent SUMOylation pathway could be the target for developing LRAs.

Increased circulating leukocyte-derived microparticles in ischemic cerebrovascular disease.

OBJECTIVES: Circulating leukocyte-derived microparticles act as proinflammatory mediators that reflect vascular inflammation. In this study, we examined the hypothesis that the quantity of leukocyte-derived microparticles is increased in patients with ischemic cerebrovascular diseases, and investigated utility of various phenotypes of leukocyte-derived microparticles as specific biomarkers of vascular inflammation injury. Additionally we focused on identifying leukocyte-derived microparticles that may be correlated with stroke severity in acute ischemic stroke patients. METHODS: The plasma concentration of leukocyte-derived microparticles obtained by a series of centrifugations of 76 consecutive patients with ischemic cerebrovascular diseases and 70 age-, sex-, and race-matched healthy controls were determined by flow cytometry. RESULTS: Significantly elevated numbers of leukocyte (CD45+), monocyte (CD14+), lymphocyte (CD4+), granulocyte (CD15+) derived microparticles were found in the plasma samples of patients ischemic cerebrovascular diseases, compared to healthy controls (p<0.05). Furthermore, the plasma levels of CD14+ microparticles were significantly correlated with stroke severity (r=0.355, p=0.019), cerebral vascular stenosis severity (r=0.255, p=0.025) and stroke subtype (r=0.242, p=0.036). No association with stroke was observed for other leukocyte-derived phenotypes. CONCLUSIONS: These results demonstrate that circulating leukocyte-derived microparticles amounts are increased in patients with ischemic cerebrovascular diseases, compared with healthy controls. As proinflammatory mediators, leukocyte-derived microparticles may contribute to vascular inflammatory and the inflammatory process in acute ischemic stroke. Levels of CD14+ microparticles may be a promising biomarker of ischemic severity and outcome of stroke in the clinic.

Phylogeography of Angiostrongylus cantonensis (Nematoda: Angiostrongylidae) in southern China and some surrounding areas.

Angiostrongylus cantonensis is of increasing public health importance as the main zoonotic pathogen causing eosinophilic meningitis or meningoencephalitis, which has been documented all over the world. However, there are very limited studies about its phylogeography and spread pattern. In the present study, the phylogeography of A. cantonensis in southern China (including Taiwan) and partial areas of Southeast Asia were studied based on the sequences of complete mitochondrial cytochrome b (Cytb) gene. A total of 520 individuals of A. cantonensis obtained from 13 localities were sequenced for the analyses and grouped into 42 defined haplotypes. The phylogenetic tree (NJ tree and BI tree) revealed a characteristic distribution pattern of the four main lineages, with detectable geographic structure. Genetic differentiation among populations was significant, but demographic expansion could not be detected by either neutrality tests or mismatch distribution analysis, which implied a low gene flow among the local populations in different regions where the samples were collected. Two unique lineages of the A. cantonensis population in Taiwan were detected, which suggests its multiple origin in the island. Populations in Hekou (China) and Laos showed the highest genetic diversities, which were supported by both genetic diversity indices and AMOVA. These results together infer that the area around Thailand or Hekou in Yunnan province, China are the most likely origins of Angiostrongylus cantonensis.

Complete mitochondrial genome of the giant African snail, Achatina fulica (Mollusca: Achatinidae): a novel location of putative control regions (CR) in the mitogenome within Pulmonate species.

The whole sequence (15,057 bp) of the mitochondrial DNA (mtDNA) of the terrestrial snail Achatina fulica (order Stylommatophora) was determined. The mitogenome, as the typical metazoan mtDNA, contains 13 protein-coding genes (PCG), 2 ribosomal RNA genes (rRNA) and 22 transfer RNA genes (tRNA). The tRNA genes include two trnS without standard secondary structure. Interestingly, among the known mitogenomes of Pulmonata species, we firstly characterized an unassigned lengthy sequence (551 bp) between the cox1 and the trnV which may be the CR for the sake of its AT bases usage bias (65.70%) and potential hairpin structure.