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Toxoplasma, an important intracellular parasite of humans and animals, causes life-threatening toxoplasmosis in immunocompromised individuals. Although Toxoplasma secretory proteins during acute infection (tachyzoite, which divides rapidly and causes inflammation) have been extensively characterized, those involved in chronic infection (bradyzoite, which divides slowly and is surrounded by a cyst wall) remain uncertain. Regulation of the cyst wall is essential to the parasite life cycle, and polysaccharides, such as chitin, in the cyst wall are necessary to sustain latent infection. Toxoplasma secretory proteins during the bradyzoite stage may have important roles in regulating the cyst wall via polysaccharides. Here, we focused on characterizing the hypothetical T. gondii chitinase, chitinase-like protein 1 (TgCLP1). We found that the chitinaselike domain containing TgCLP1 is partially present in the bradyzoite microneme and confirmed, albeit partially, its previous identification in the tachyzoite microneme. Furthermore, although parasites lacking TgCLP1 could convert from tachyzoites to bradyzoites and make an intact cyst wall, they failed to convert from bradyzoites to tachyzoites, indicating that TgCLP1 is necessary for bradyzoite reactivation. Taken together, our findings deepen our understanding of the molecular basis of recrudescence and could contribute to the development of novel strategies for the control of toxoplasmosis. [ABSTRACT FROM AUTHOR]

In previous interactional studies of formats for utterances doing requests, attention has been given to the initial verb (such as can/could or wonder) and possibly the subject (especially I vs you). The current study examines the main types of grammatical variation found in what we call the “x component,” that is the segment after the initial verb and subject. We examine two types of requests: those with can you x and those with wonder x, and we find that variations in the x component in these requests are associated with variations in the unfolding development of the request sequences. We thus suggest that the x component is crucial to the interactional work accomplished by the requesting utterance.

Toxoplasma gondii establishes chronic infection by forming tissue cysts, and this chronic infection is one of the most common parasitic infections in humans. Our recent studies revealed that whereas CD8+ T cells of genetically resistant BALB/c mice have the capability to remove the tissue cysts of the parasite through their perforin-mediated activities, small portions of the cysts are capable of persisting in the presence of the anti-cyst CD8+ T cells. It is currently unknown how those small portions of the cysts resist or escape the T-cell immunity and persist in the hosts. In the present study, we discovered that the cysts, which persisted in the presence of the perforin-mediated CD8+ T-cell immunity, have significantly greater mRNA levels for four dense granule proteins, GRA1, GRA2, GRA3, and GRA7, and one rhoptry protein, ROP35, than the total population of the cysts present in the absence of the T cells. In addition, increased levels of mRNA for GRA1, GRA3, and ROP35 in the cysts significantly correlated with their successful persistence through the condition in which greater degrees of reduction of the cyst burden occurred through anti-cyst CD8+ T cells. In addition, GRA3-deficient T. gondii displayed significantly enhanced elimination of the cysts by anti-cyst CD8+ T cells when compared to the wild-type parasite. These results indicate that GRA3 is a key molecule that mediates in the capability of T. gondii cysts to persist by resisting or evading the anti-cyst activity of CD8+ T cells during the later stage of infection. [ABSTRACT FROM AUTHOR]

The goal of the current paper is to describe the results of an empirical study of tutoring dialogue, with special attention on the issue of correction in tutoring. In particular, this paper presents findings which strongly suggest that the ever> day preference for self-correction (Pomerantz, 1975) is maintained even in a heavily knowledge-asymmetric situation like tutoring. For further details of this study, readers should consult Fox (1993).