Solution structure of the DNA-binding domain of human telomeric protein, hTRF1

AbstractBackground: Mammalian telomeres consist of long tandem arrays of the double-stranded TTAGGG sequence motif packaged by a telomere repeat binding factor, TRF1. The DNA-binding domain of TRF1 shows sequence homology to each of three tandem repeats of the DNA-binding domain of the transcriptional activator c-Myb. The isolated c-Myb-like domain of human TRF1 (hTRF1) binds specifically to telomeric DNA as a monomer, in a similar manner to that of homeodomains. So far, the only three-dimensional structure of a telomeric protein to be determined is that of a yeast telomeric protein, Rap1p. The DNA-binding domain of Rap1p contains two subdomains that are structurally closely related to c-Myb repeats. We set out to determine the solution structure of the DNA-binding domain of hTRF1 in order to establish its mode of DNA binding.Results: The solution structure of the DNA-binding domain of hTRF1 has been determined and shown to comprise three helices. The architecture of the three helices is very similar to that of each Rap1p subdomain and also to that of each c-Myb repeat. The second and third helix form a helix-turn-helix (HTH) variant. The length of the third helix of hTRF1 is similar to that of the second subdomain of Rap1p.Conclusions: The hTRF1 DNA-binding domain is likely to bind to DNA in a similar manner to that of the second subdomain of Rap1p. On the basis of the Rap1p–DNA complex, a model of the hTRF1 DNA-binding domain in complex with human telomeric DNA was constructed. In addition to DNA recognition by the HTH variant, a flexible N-terminal arm of hTRF1 is likely to interact with DNA

Controlling Electronic States of Few-walled Carbon Nanotube Yarn via Joule-annealing and p-type Doping Towards Large Thermoelectric Power Factor

Flexible, light-weight and robust thermoelectric (TE) materials have attracted much attention to convert waste heat from low-grade heat sources, such as human body, to electricity. Carbon nanotube (CNT) yarn is one of the potential TE materials owing to its narrow band-gap energy, high charge carrier mobility, and excellent mechanical property, which is conducive for flexible and wearable devices. Herein, we propose a way to improve the power factor of CNT yarns fabricated from few-walled carbon nanotubes (FWCNTs) by two-step method; Joule-annealing in the vacuum followed by doping with p-type dopants, 2,3,5,6-tetrafluo-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Numerical calculations and experimental results explain that Joule-annealing and doping modulate the electronic states (Fermi energy level) of FWCNTs, resulting in extremely large thermoelectric power factor of 2250 mu Wm(-1) K-2 at a measurement temperature of 423K. Joule-annealing removes amorphous carbon on the surface of the CNT yarn, which facilitates doping in the subsequent step, and leads to higher Seebeck coefficient due to the transformation from (semi) metallic to semiconductor behavior. Doping also significantly increases the electrical conductivity due to the effective charge transfers between CNT yarn and F4TCNQ upon the removal of amorphous carbon after Joule-annealing

Toxoplasma gondii prevalence and risk factors in owned domestic cats from Nakhon Pathom Province, Thailand

Domestic cats are a potential source of Toxoplasma gondii infection for humans. This study was conducted to determine the seroprevalence and risk factors for T. gondii infection in domestic cats. Cat sera (n = 182) were tested for T. gondii IgG antibodies using the latex agglutination test (LAT) and the GRA7 of T. gondii (TgGRA7)-indirect enzyme-linked immunosorbent assay (iELISA). Univariable and multivariable logistic regression analyses were used to identify the factors associated with T. gondii infection. The overall prevalence rates were 18.1% (33/182) according to LAT, 19.2% (35/182) according to the iELISA and 17.0% (31/182) according to LAT and iELISA. Univariable analyses identified, outdoor access (P = 0.006), being a former stray cat (P = 0.001) and successful hunting behaviors (P = 0.04) as risk factors for T. gondii infection. Outdoor access (OR 2.63, 95% confidence interval (CI) 1.03–6.72) and is a former stray cat (OR 3.69, 95% CI 1.52–8.96) remained significant risk factors in multivariable analyses. This study indicated a relatively high seroprevalence of T. gondii among domestic cats. Cat owners can reduce the risk for T. gondii infection by not allowing their cats to roam free. Furthermore, education about the transmission of the parasite should be provided to prevent infection to the owners

Toxoplasma gondii and Neospora caninum prevalence and risk factors on goat farms in Kanchanaburi province, Thailand

Toxoplasma gondii and Neospora caninum are apicomplexan protozoan parasites that have been associated with reproductive problems in ruminants. Despite the high seroprevalence of T. gondii and N. caninum reported in goats worldwide, little information about the seroprevalence of these parasites in goats in Thailand. In this study, we investigated the seroprevalence of T. gondii and N. caninum in 389 goat samples from five districts of Kanchanaburi province, Thailand. An indirect enzyme-linked immunosorbent assay (iELISA) using recombinant TgGRA7 and NcSAG1 antigens was used for the detection of anti-T.gondii and anti-N.caninum antibodies, respectively. Risk factors for the occurrence of these protozoan parasites on goat farms were also assessed. Specific IgG against T. gondii and N. caninum was detected in 28.5% and 16.7% samples, respectively. Co-infections were observed in 11.8% of samples. The risk factors significantly associated with T. gondii seroprevalence was the presence of cats (odds ratio [OR]= 2.55, 95% confidential interval [CI]=1.67- 3.89). The presence of other domestic animals on farm contributed to the risk of T. gondii and N. caninum infection on goat farms (OR=1.692, 95% CI= 1.08- 2.63). The present study provides data on the seroprevalence and risk of T. gondii and N. caninum infections among goats in Kanchanaburi province, Thailand. Integrated and efficient measures are required to prevent and control infections on goat farms

Benzene Metabolite 1,2,4-Benzenetriol Induces Halogenated DNA and Tyrosines Representing Halogenative Stress in the HL-60 Human Myeloid Cell Line

Background: Although benzene is known to be myelotoxic and to cause myeloid leukemia in humans, the mechanism has not been elucidated

Immunoproteomics to identify species-specific antigens in Neospora caninum recognised by infected bovine sera

Bovine neosporosis is a disease of concern due to its global distribution and significant economic impact through massive losses in the dairy and meat industries. To date, there is no effective chemotherapeutic drug or vaccine to prevent neosporosis. Control of this disease is therefore dependent on efficient detection tests that may affect treatment management strategies. This study was conducted to identify the specific immunoreactive proteins of Neospora caninum tachyzoites recognised by sera from cattle infected with N. caninum, Toxoplasma gondii, Cryptosporidium parvum, Babesia bovis and B. bigemina, and by sera from uninfected cattle using two-DE dimensional gel electrophoresis (2-DE) combined with immunoblot and mass spectrometry (LC-MS/MS). Among 70 protein spots that reacted with all infected sera, 20 specific antigenic spots corresponding to 14 different antigenic proteins were recognised by N. caninum-positive sera. Of these immunoreactive antigens, proteins involved in cell proliferation and invasion process were highly immunogenic, including HSP90-like protein, putative microneme 4 (MIC4), actin, elongation factor 1-alpha and armadillo/beta-catenin-like repeat-containing protein. Interestingly, we discovered an unnamed protein product, rhoptry protein (ROP1), possessing strong immunoreactivity against N. caninum but with no data on function available. Moreover, we identified cross-reactive antigens among these apicomplexan parasites, especially N. caninum, T. gondii and C. parvum. Neospora caninum-specific immunodominant proteins were identified for immunodiagnosis and vaccine development. The cross-reactive antigens could be evaluated as potential common vaccine candidates or drug targets to control the diseases caused by these apicomplexan protozoan parasites

Biochemical Studies of Mitochondrial Malate: Quinone Oxidoreductase from Toxoplasma gondii

Toxoplasma gondii is a protozoan parasite that causes toxoplasmosis and infects almost one-third of the global human population. A lack of effective drugs and vaccines and the emergence of drug resistant parasites highlight the need for the development of new drugs. The mitochondrial electron transport chain (ETC) is an essential pathway for energy metabolism and the survival of T. gondii. In apicomplexan parasites, malate:quinone oxidoreductase (MQO) is a monotopic membrane protein belonging to the ETC and a key member of the tricarboxylic acid cycle, and has recently been suggested to play a role in the fumarate cycle, which is required for the cytosolic purine salvage pathway. In T. gondii, a putative MQO (TgMQO) is expressed in tachyzoite and bradyzoite stages and is considered to be a potential drug target since its orthologue is not conserved in mammalian hosts. As a first step towards the evaluation of TgMQO as a drug target candidate, in this study, we developed a new expression system for TgMQO in FN102(DE3)TAO, a strain deficient in respiratory cytochromes and dependent on an alternative oxidase. This system allowed, for the first time, the expression and purification of a mitochondrial MQO family enzyme, which was used for steady-state kinetics and substrate specificity analyses. Ferulenol, the only known MQO inhibitor, also inhibited TgMQO at IC50 of 0.822 μM, and displayed different inhibition kinetics compared to Plasmodium falciparum MQO. Furthermore, our analysis indicated the presence of a third binding site for ferulenol that is distinct from the ubiquinone and malate sites

Recent Mortality from Pleural Mesothelioma, Historical Patterns of Asbestos Use, and Adoption of Bans: A Global Assessment

[[abstract]]BACKGROUND: In response to the health risks posed by asbestos exposure, some countries have imposed strict regulations and adopted bans, whereas other countries have intervened less and continue to use varying quantities of asbestos. OBJECTIVES: This study was designed to assess, on a global scale, national experiences of recent mortality from pleural mesotheliomal historical trends in asbestos use, adoption of bans, and their possible interrelationships. METHODS: For 31 countries with available data, we analyzed recent pleural mesothelioma (International Classification of Diseases, 10th Revision) mortality rates (MRs) using age-adjusted period MRs (deaths/million/year) from 1996 to 2005. We calculated annual percent changes (APCs) in age-adjusted MRs to characterize trends during the period. We characterized historical patterns of asbestos use by per capita asbestos use (kilograms per capita/year) and the status of national bans. RESULTS: Period MRs increased with statistical significance in five countries, with marginal significance in two countries, and were equivocal in 24 countries (five countries in Northern and Western Europe recorded negative APC values). Countries adopting asbestos bans reduced use rates about twice as fast as those not adopting bans. Turning points in use preceded bans. Change in asbestos use during 1970-1985 was a significant predictor of APC in mortality for pleural mesothelioma, with an adjusted R-2 value of 0.47 (p < 0.0001). CONCLUSIONS: The observed disparities in global mesothelioma trends likely relate to country-to-country disparities in asbestos use trends

Toxoplasma Effector TgIST Targets Host IDO1 to Antagonize the IFN-γ-Induced Anti-parasitic Response in Human Cells

Toxoplasma gondii is an important human and animal pathogen that causes life-threatening toxoplasmosis. Interferon-γ (IFN-γ) is critical for anti-T. gondii cell-autonomous immunity in both humans and mice. To proliferate efficiently within the hosts, virulent strains of T. gondii can suppress IFN-γ-dependent immunity. During parasite infection, it is well-characterized that various virulence effectors are secreted to transcriptionally or post-translationally target IFN-γ-inducible GTPases, which are essential for anti-parasite responses in mice. However, the role of IFN-γ-inducible GTPases in anti-T. gondii responses in human cells is controversial since they are non-functional or absent in humans. Instead, IFN-γ-induced tryptophan degradation by indole-2,3-dioxygenase (IDO) is important for the anti-T. gondii human response. To date, the T. gondii virulent mechanism targeting IDO in human cells remains elusive. Here we show that although humans possess two IDO isozymes, IDO1 and IDO2, human cells of various origins require IDO1 but not IDO2 for IFN-γ-induced cell-autonomous immunity to T. gondii. T. gondii secretes an effector TgIST to inhibit IDO1 mRNA expression. Taken together, the data suggests that T. gondii possesses virulence programs operated by TgIST to antagonize IFN-γ-induced IDO1-mediated anti-parasite cell-autonomous immunity in human cells