Mitochondrial NAD+ Controls Nuclear ARTD1-Induced ADP-Ribosylation

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Superantigen-induced regulatory T cells display different suppressive functions in the presence or absence of natural CD4+CD25+ regulatory T cells in vivo

Repeated exposures to both microbial and innocuous Ags in vivo have been reported to both eliminate and tolerize T cells after their initial activation and expansion. The remaining tolerant T cells have been shown to suppress the response of naive T cells in vitro. This feature is reminiscent of natural CD4(+)CD25(+) regulatory T cells. However, it is not known whether the regulatory function of in vivo-tolerized T cells is similar to the function of natural CD4(+)CD25(+) regulatory T cells. In this study, we demonstrate that CD4(+)CD25(+) as well as CD4(+)CD25(-) T cells isolated from mice treated with superantigen three consecutive times to induce tolerance were functionally comparable to natural CD4(+)CD25(+) regulatory T cells, albeit more potent. The different subpopulations of in vivo-tolerized CD4(+) T cells efficiently down-modulated costimulatory molecules on dendritic cells, and their suppressive functions were strictly cell contact dependent. Importantly, we demonstrate that conventional CD4(+)CD25(-) T cells could also be induced to acquire regulatory functions by the same regimen in the absence of natural regulatory T cells in vivo, but that such regulatory cells were functionally different.     

Different modes of programmed cell death during oogenesis of the silkmoth Bombyx mori

It is increasingly recognized that programmed cell death includes not only apoptosis and autophagy, but also other types of nonapoptotic cell death, such as paraptosis, which are all characterized by distinct morphological features. Our findings indicate that all three types of programmed cell death occur in the ovarian nurse cell cluster during late vitellogenesis (formation of the egg yolk) of Bombyx mori (Lepidoptera), whereas middle vitellogenesis is exclusively characterized by the presence of a nonapoptotic type of cell death, known as paraptosis. During middle vitellogenesis, nurse cells exhibit clearly cytoplasmic vacuolization, as revealed by ultrastructural examination performed through conventional light and transmission electron microscopy, while no signs of apoptotic or autophagic features are detectable. Moreover, nurse cells of developmental stages 7, 8 and 9 contain autophagic compartments, as well as apoptotic characteristics, such as condensed chromatin, fragmented DNA and activated caspases, as revealed by in vitro assays. We propose that paraptosis precedes both apoptosis and autophagy during vitellogenesis, since its initial activation is detectable during middle vitellogenesis, whereas no apoptotic nor autophagic features are observed. In contrast, at the late stages of Bombyx mori oogenesis, paraptosis, autophagy and apoptosis operate synergistically, resulting in a more efficient elimination of the degenerated nurse cells.     

Cuticular wax profiles of leaves of some traditionally used African Bignoniaceae

Bignoniaceae, Newbouldia laevis, Markhamia acuminata, Spathodea campanulata and Kigelia africana were analysed by GC-MS. The principal constituents were represented by a homologous series of n-alkanes (C23-C33), n-alcohols (C18-C30) and related carboxylic acids (C16-C36). For N. laevis and M. acuminata, ursolic and oleanolic acid were the most abundant wax components (52 and 60%, respectively), followed by the C29, the C31 and the C33 n-alkanes. The predominant components of S. campanulata were n-alcohols (35%), with octacosanol and triacontanol as the most abundant ones, while K. africana is distinguished from these three members by the conspicuous absence of triterpenoic acids and the predominance of n-alkanes (70%) with hentriacontane and tritriacontane as the main representatives. Other notable constituents were sterols, albeit present in trace amounts. The wax profiles are discussed in terms of taxonomic characters.     

Timing of autumn bird migration under climate change: advances in long-distance migrants,delays in short-distance migrants

As a response to increasing spring temperature in temperate regions in recent years, populations of many plant and animal species, including migratory birds, have advanced the seasonal start of their reproduction or growth. However, the effects of climate changes on subsequent events of the annual cycle remain poorly understood. We investigated long-term changes in the timing of autumn migration in birds, a key event in the annual cycle limiting the reproductive period. Using data spanning a 42-year period, we analysed long-term changes in the passage of 65 species of migratory birds through Western Europe. The autumn passage of migrants wintering south of the Sahara has advanced in recent years, presumably as a result of selection pressure to cross the Sahel before its seasonal dry period. In contrast, migrants wintering north of the Sahara have delayed autumn passage. In addition, species with a variable rather than a fixed number of broods per year have delayed passage, possibly because they are free to attempt more broods. Recent climate changes seem to have a simple unidirectional effect on the seasonal onset of reproduction, but complex and opposing effects on the timing of subsequent events in the annual cycle, depending on the ecology and life history of a species. This complicates predictions of overall effects of global warming on avian communities.     

Immunologically induced,complement-dependent up-regulation of the prion protein in the mouse spleen: follicular dendritic cells versus capsule and trabeculae

The expression of the prion protein (PrP) in the follicular dendritic cell network of germinal centers in the spleen is critical for the splenic propagation of the causative agent of prion diseases. However, a physiological role of the prion protein in the periphery remains elusive. To investigate the role and function of PrP expression in the lymphoid system we treated naive mice i.v. with preformed immune complexes or vesicular stomatitis virus. Immunohistochemistry and Western blot analysis of the spleen revealed that 8 days after immunization, immune complexes and vesicular stomatitis virus had both induced a strong increase of PrP expression in the follicular dendritic cell network. Remarkably, this up-regulation did not occur in mice that lack an early factor of the complement cascade, C1q, a component which has been shown previously to facilitate early prion pathogenesis. In addition to the variable PrP level in the germinal centers, we detected steady and abundant PrP expression in the splenic capsule and trabeculae, which are structural elements that have not been associated before with PrP localization. The abundant trabeculo-capsular PrP expression was also evident in spleens of Rag-1-deficient mice, which have been shown before to be incapable of prion expansion. We conclude that trabeculocapsular PrP is not sufficient for splenic prion propagation. Furthermore, our observations may provide important clues for a physiological function of the prion protein and allow a new view on the role of complement and PrP in peripheral prion pathogenesis.     

Viral escape from the neutralizing antibody response: the lymphocytic choriomeningitis virus model

In addition to CD8+ cytotoxic T lymphocyte (CTL) responses, neutralizing antibodies contribute substantially to the long-term immune control of noncytopathic viruses, as demonstrated during infection with the lymphocytic choriomeningitis virus (LCMV). The high virus load during the initial phase of an infection and the ability of this RNA virus to spontaneously acquire mutations are important prerequisites for escaping an ongoing immune response. In this context, LCMV escape from the humoral response by single point mutations in neutralizing envelope protein determinants may occur, particularly during conditions of CTL deficiency, leading to virus persistence.