Parasite Manipulation of the Invariant Chain and the Peptide Editor H2-DM Affects Major Histocompatibility Complex Class II Antigen Presentation during Toxoplasma gondii Infection

Toxoplasma gondii is an obligate intracellular protozoan parasite. This apicomplexan is the causative agent of toxoplasmosis, a leading cause of central nervous system disease in AIDS. It has long been known that T. gondii interferes with major histocompatibility complex class II (MHC-II) antigen presentation to attenuate CD4(+) T cell responses and establish persisting infections. Transcriptional downregulation of MHC-II genes by T. gondii was previously established, but the precise mechanisms inhibiting MHC-II function are currently unknown. Here, we show that, in addition to transcriptional regulation of MHC-II, the parasite modulates the expression of key components of the MHC-II antigen presentation pathway, namely, the MHC-II-associated invariant chain (Ii or CD74) and the peptide editor H2-DM, in professional antigen-presenting cells (pAPCs). Genetic deletion of CD74 restored the ability of infected dendritic cells to present a parasite antigen in the context of MHC-II in vitro. CD74 mRNA and protein levels were, surprisingly, elevated in infected cells, whereas MHC-II and H2-DM expression was inhibited. CD74 accumulated mainly in the endoplasmic reticulum (ER), and this phenotype required live parasites, but not active replication. Finally, we compared the impacts of genetic deletion of CD74 and H2-DM genes on parasite dissemination toward lymphoid organs in mice, as well as activation of CD4(+) T cells and interferon gamma (IFN-γ) levels during acute infection. Cyst burdens and survival during the chronic phase of infection were also evaluated in wild-type and knockout mice. These results highlight the fact that the infection is influenced by multiple levels of parasite manipulation of the MHC-II antigen presentation pathway

Radiation exposure and circulatory disease risk: Hiroshima and Nagasaki atomic bomb survivor data, 1950-2003

Objective To investigate the degree to which ionising radiation confers risk of mortality from heart disease and stroke

ラオス ニオケル ショウガッコウ リカ ノ カダイ

ラオスにおける理科教育の課題を探るために調査を行った。その結果，教科書に児童の日常生活にそぐわない内容が存在するため，児童が混乱し，習熟度の低下を招く結果となっていること，身近な自然現象を学習していくため，現象に共通する科学的概念の修得にはいたっていないことが明らかとなった。また，児童は日常生活の中で素朴概念を形成しており，教え込む授業ではなく，生徒たちが持っている考えを生かしながら授業をすることにより，知識の転換をはかっていくことが重要であること，教科書を教え込む授業が多く見られることから，今後，観察や実験を取り入れ，体験的理解を促すことにより科学的概念を身につける方策をとる必要があることが明らかとなった。We conducted a study to clarify some issues in Science Education in Lao People’s Democratic Republic. We found that some contents of textbook are not suiting pupils’ everyday life. As a result of it, some pupils get confused and end up in lower learning levels than expected. At the same time, since they study natural science through their everyday experience, it is hard for them to connect different scientific concepts behind various phenomena. Therefore, instead of teaching scientific concepts by simple lectures, it is important to use pupils’ opinions and ideas as the basis for the class. This way, pupils lean not only what is in the textbooks, but also some application of knowledge outside textbooks. We also suggest adopting more observation and experiment where students learn scientific concepts through hands on experience

Effect of plastic-type and photocatalyst concentration on plastic film degradation using TIO2

Microplastics, small plastic pieces less than 5 mm in size, are one of the most con- cerning pollutants that can be harmful to the environment and its biota today. Because of their high abundance and small particle size, microplastics are known to be easily ingested by micro organisms and affect many organisms as they move through the food chain. In addition, there is concern that microplastics can be vectors of hazardous substances as they are known to adsorb persistent organic pollutants (POPs) in the environment. However, an efficient treatment method for removing microplastics in wastewater has yet to be established. In recent years, research on introducing photocatalytic o idative degradation systems into wastewater treatment plants (WWTPs) was reported for the potential removal of microplastics from wastewater. Neverthe less, previous reports only focused on developing and evaluating photocatalysts suitable for microplastic degradation, and the e amination of the effects of the types of plastic and photocat alyst concentration on microplastic degradation remains limited. The aim of this study is to eval uate the effect of plastic type and photocatalyst concentration on the degradation of plastic. We used four types of plastic films in the e periment: low-density polyethylene (LDPE), high-den sity polyethylene (HDPE), polypropylene (PP) and polyethylene terephthalate (PET), where the degradation of the plastic was measured by weight. The most used and commercially available TiO2 (P25) was used as a photocatalyst with different concentrations from 0.001 to 1.0 g L-1. The plastic degradation e periment used 3.30 cm squares films with 25 to 30 µm thickness under ultraviolet light irradiation using nine black-light fluorescent lamps (6 W; wavelength: 340-400 nm). The degradation and surface morphology of the plastic film was evaluated by measuring weight loss, carbonyl inde , and scanning electron microscopy. The result showed the LDPE had the highest weight loss compared to other plastic types, which could be due to its simple structure consisting solely of C-H single bonds. Additionally, the highest degradation rate was observed when the photocatalyst concentration was 0.01 g L-1. The reason for the degradation rate decrease at concentrations above 0.01 g L-1 was probably due to the self-light shielding effect of TiO . The low degradation rate at a lower concentration of less than 0.01 g L-1 could be due to insufficient catalyst concentration. In the future, it will be important to analyze the degradation pathways by measuring intermediates during the degrading process for each plastic type.departmental bulletin pape

Real-Time PCR Assay for the Diagnosis and Quantification of Co-infections by Diaporthe batatas and Diaporthe destruens in Sweet Potato

Foot rot disease caused by Diaporthe destruens (formerly Plenodomus destruens) has become a major concern for the production of sweet potato [Ipomoea batatas (L.) Lam.] in Japan. A related fungus Diaporthe batatas, which causes dry rot disease of sweet potato, is native and is widespread in fields in Japan. The similar characteristics of these two pathogens pose a challenge for conventional disease diagnosis. Currently, there are no effective molecular measures for identifying and distinguishing D. destruens and D. batatas. Here, we demonstrate a real-time PCR assay that distinguishes and quantifies D. batatas and D. destruens from co-infected sweet potato. The assay was performed with various simulated DNA combinations of D. batatas and D. destruens ranging from 1:1 to 1:100000. The assay was also used with the ratios of D. batatas: D. destruens: sweet potato DNA ranging from 1:1:1 to 1:1:100000. These assays produced a specific amplification product for each of the pathogens, and quantified the fungal biomass over the entire range tested without detecting false positives. The assay was validated by using infected sweet potato collected from various fields; it showed sufficient sensitivity and specificity to quantify and distinguish D. batatas and D. destruens from these field samples. Thus, our real-time PCR assay would be a useful tool for diagnosis of D. batatas and D. destruens and is expected to provide the foundation for the design of integrated disease management strategies for foot rot disease in sweet potato

Education level and physical functional limitations among Japanese community residents-gender difference in prognosis from stroke

<p>Abstract</p> <p>Background</p> <p>Little research has been conducted to examine the relationship between education level and functional limitations among Japanese community residents. We sought to examine the association between education level and physical functional limitations among Japanese men and women, and whether that association was modified by gender and history of stroke.</p> <p>Methods</p> <p>We examined prevalence of physical functional limitation by educational level using the data from a total of 29,134 Japanese men and women aged 50–69 years living in communities in 2000. The information of educational level (junior high school graduates, senior high school graduates, college and/or higher education) and physical functional limitations (no need for assistance, need for assistance when going outdoors, and need for assistance to carry out indoor activities) were obtained by self-administrated questionnaire.</p> <p>Results</p> <p>The proportions of the subjects reported their highest level of schooling were 48% for junior high school, 39% for high school, and 13% for college. Three hundred and twenty eight subjects (1% of total subjects) reported having some physical functional limitations. Multinomial logistic regression analyses showed that the odds ratio of needing assistance to carry out indoor activities were 4.84(95%CI:3.61,6.50) for lowest education level group and 2.21(95%CI:1.00,4.86) for middle education level group compared to highest education level group. The corresponding odds ratios of needing assistance when going outdoors were 2.36(95%CI: 2.03,2.72) and 1.08(95%CI:0.73,1.60), respectively. Further, the significant excess prevalence of having functional limitations associated with the low education level was identified for men regardless of history of stroke and for women without history of stroke.</p> <p>Conclusion</p> <p>Low education level was associated with the higher prevalence of physical functional limitations for both genders. That association among persons with history of stroke was observed for men but not for women probably due to gender differences in stroke subtypes and social support.</p

Cell cycle regulation of organelle biogenesis and apicoplast protein trafficking in Toxoplasma gondii

Apicomplexan parasites employ an unusual mechanism for cell replication, assembling daughters within the mother. Because rapid multiplication correlates with pathogenesis, it is important to understand the coordination of parasite assembly. Organellar segregation is critical in these organisms harboring single copy organelles, and their highly polarized subcellular organization is essential for host cell invasion. In order to understand how these unicellular eukaryotes efficiently package a complete set of organelles, we have used time-lapse microscopy of fluorescent markers targeted to various subcellular structures, and constructed a complete timetable for organellokinesis in Toxoplasma gondii. Golgi division and elongation of the apicoplast (a secondary endosymbiotic plastid) are among the first morphologically observable events, associated with centriole migration and preceding the formation of the daughter cytoskeletal scaffolds. Cytoskeletal growth proceeds from the apical end of the parasite, first encapsulating the ER/Golgi from which the apical secretory organelles are produced de novo. Further growth of the cytoskeletal scaffold results in the partition of the apicoplast, nucleus, and ultimately the mitochondrion, which enters the developing daughters rapidly and late during mitosis. Defining an accurate timetable for organellokinesis permitted a detailed analysis of nuclear-encoded protein trafficking to the apicoplast. The targeting of nuclear-encoded apicoplast lumenal proteins is dependent on a bipartite N-terminal extension consisting of a signal sequence followed by a transit peptide; but the targeting of an apicoplast membrane protein (a phosphate translocator) is not. Analysis using fluorescence recovery after photobleaching shows that proteins target to the apicoplast via vesicles only when the organelle is elongating prior to daughter cell formation. Electron microscopy reveals that these vesicles are morphologically distinct from other known ER or Golgi-derived vesicles. Treatment with Brefeldin A or overexpression of dominant negative mutation of ADP-ribosylation factor 1 causes apicoplast lumenal or membrane proteins to accumulate in the ER or the tubulo-vesicular Golgi region respectively, only during the apicoplast elongation stage. In sum, these results indicate a tight correlation between organelle biogenesis, protein trafficking and cell division in T. gondii

Cell cycle regulation of organelle biogenesis and apicoplast protein trafficking in Toxoplasma gondii

Apicomplexan parasites employ an unusual mechanism for cell replication, assembling daughters within the mother. Because rapid multiplication correlates with pathogenesis, it is important to understand the coordination of parasite assembly. Organellar segregation is critical in these organisms harboring single copy organelles, and their highly polarized subcellular organization is essential for host cell invasion. In order to understand how these unicellular eukaryotes efficiently package a complete set of organelles, we have used time-lapse microscopy of fluorescent markers targeted to various subcellular structures, and constructed a complete timetable for organellokinesis in Toxoplasma gondii. Golgi division and elongation of the apicoplast (a secondary endosymbiotic plastid) are among the first morphologically observable events, associated with centriole migration and preceding the formation of the daughter cytoskeletal scaffolds. Cytoskeletal growth proceeds from the apical end of the parasite, first encapsulating the ER/Golgi from which the apical secretory organelles are produced de novo. Further growth of the cytoskeletal scaffold results in the partition of the apicoplast, nucleus, and ultimately the mitochondrion, which enters the developing daughters rapidly and late during mitosis. Defining an accurate timetable for organellokinesis permitted a detailed analysis of nuclear-encoded protein trafficking to the apicoplast. The targeting of nuclear-encoded apicoplast lumenal proteins is dependent on a bipartite N-terminal extension consisting of a signal sequence followed by a transit peptide; but the targeting of an apicoplast membrane protein (a phosphate translocator) is not. Analysis using fluorescence recovery after photobleaching shows that proteins target to the apicoplast via vesicles only when the organelle is elongating prior to daughter cell formation. Electron microscopy reveals that these vesicles are morphologically distinct from other known ER or Golgi-derived vesicles. Treatment with Brefeldin A or overexpression of dominant negative mutation of ADP-ribosylation factor 1 causes apicoplast lumenal or membrane proteins to accumulate in the ER or the tubulo-vesicular Golgi region respectively, only during the apicoplast elongation stage. In sum, these results indicate a tight correlation between organelle biogenesis, protein trafficking and cell division in T. gondii

The motility of a human parasite, Toxoplasma gondii, is regulated by a novel lysine methyltransferase.

Protozoa in the phylum Apicomplexa are a large group of obligate intracellular parasites. Toxoplasma gondii and other apicomplexan parasites, such as Plasmodium falciparum, cause diseases by reiterating their lytic cycle, comprising host cell invasion, parasite replication, and parasite egress. The successful completion of the lytic cycle requires that the parasite senses changes in its environment and switches between the non-motile (for intracellular replication) and motile (for invasion and egress) states appropriately. Although the signaling pathway that regulates the motile state switch is critical to the pathogenesis of the diseases caused by these parasites, it is not well understood. Here we report a previously unknown mechanism of regulating the motility activation in Toxoplasma, mediated by a protein lysine methyltransferase, AKMT (for Apical complex lysine (K) methyltransferase). AKMT depletion greatly inhibits activation of motility, compromises parasite invasion and egress, and thus severely impairs the lytic cycle. Interestingly, AKMT redistributes from the apical complex to the parasite body rapidly in the presence of egress-stimulating signals that increase [Ca²⁺] in the parasite cytoplasm, suggesting that AKMT regulation of parasite motility might be accomplished by the precise temporal control of its localization in response to environmental changes