Virus-specific CD4+ and CD8+ cytotoxic T-cell responses and long-term T-cell memory in individuals vaccinated against polio

The presence of poliovirus (PV)-specific CD4(+) T cells in individuals vaccinated against polio has been shown, but CD8(+) T-cell responses have not been described. Here, we functionally characterize the CD4(+) T-cell response and show for the first time that dendritic cells and macrophages can stimulate PV-specific CD8(+) T-cell responses in vitro from vaccinees. Both CD4(+) T and CD8(+) T cells secrete gamma interferon in response to PV antigens and are cytotoxic via the perforin/granzyme B-mediated pathway. Furthermore, the T cells also recognize and kill Sabin 1 vaccine-infected targets. The macrophage-stimulated CD4(+) T and CD8(+) T cells most likely represent memory T cells that persist for long periods in vaccinated individuals. Thus, immunity to PV vaccination involves not only an effective neutralizing antibody titer but also long-term CD4(+) and CD8(+) cytotoxic T-cell responses.     

Variable domains and a VpreB-like molecule are present in a jawless vertebrate

Immunoglobulins (Igs) and T cell antigen receptors (TCRs) that undergo somatic diversification have not been identified in the two extant orders of jawless vertebrates, which occupy essential positions in terms of understanding the evolution of the emergence of adaptive immunity. Using a single motif-dependent PCR-based approach coupled with a vector that allows selection of cDNAs encoding secretion signal sequences, four different genes encoding Ig V-type domains were identified in the sea lamprey (Petromyzon marinus). One of the predicted proteins encoded by these genes shares structural characteristics with mammalian VpreB molecules, including the absence of a recognizable transmembrane region, a relatively high proportion of charged amino acids in its C-terminal tail and distinctive features of its secretion signal peptide. This is the first indication of a molecule related to the B cell receptor (BCR) complex in a species that diverged prior to the jawed vertebrates in which RAG-mediated adaptive immunity is first encountered.Sequences described in this paper have been deposited in GenBank, with accession numbers AY576797–AY576800.     

Reconstructing immune phylogeny: new perspectives

Numerous studies of the mammalian immune system have begun to uncover profound interrelationships, as well as fundamental differences, between the adaptive and innate systems of immune recognition. Coincident with these investigations, the increasing experimental accessibility of non-mammalian jawed vertebrates, jawless vertebrates, protochordates and invertebrates has provided intriguing new information regarding the likely patterns of emergence of immune-related molecules during metazoan phylogeny, as well as the evolution of alternative mechanisms for receptor diversification. Such findings blur traditional distinctions between adaptive and innate immunity and emphasize that, throughout evolution, the immune system has used a remarkably extensive variety of solutions to meet fundamentally similar requirements for host protection.     

Revision of the genus <Emphasis Type="Italic">Placostromella</Emphasis> and inclusion of <Emphasis Type="Italic">Palawaniella castanopsis</Emphasis> as a third species

The current status of Placostromella (Ascomycota, Dothideomycetes inc. sed.) is discussed, and a third species is added to the genus based on Palawaniella castanopsis J.N. Kapoor. Both species occur on living leaves of Castanopsis (Fagaceae) in South and East Asia. Placostromella castanopsis and the type P. macrospora are fully redescribed and illustrated.     

Cold hardiness of Habrobracon hebetor (Say) (Hymenoptera: Braconidae), a parasitoid of pyralid moths

The ectoparasitoid Habrobracon hebetor (Say) attacks stored-product infesting pyralid moths that are able to overwinter under extremely cold conditions. The extent to which H. hebetor can withstand these conditions is not known, but has important implications for the ability of H. hebetor to provide long-term suppression of these pests in temperate climates. We investigated basic cold hardiness aspects of a mutant eye-color strain of H. hebetor. Feeding larvae and adults of H. hebetor had supercooling points (SCPs) at temperatures higher than those of eggs and pupae. Mean SCPs of females and males were equivalent, as were those of naked and silk-encased pupae. Feeding on honey prior to being subjected to low temperatures significantly increased the SCP of adult females by approximately 8 degrees C. Mortality of pupae and adults increased significantly whenever the temperature dropped below the mean SCP, indicating that H. hebetor does not tolerate freezing. For pupae and adults exposed to -12 and -5 degrees C, the hourly mortality rate increased with time of exposure. Pupae and adults exposed to -12 degrees C for different time intervals showed high mortality after only 1d of exposure. At -5 degrees C, none survived 12d of exposure. A better understanding of how well this parasitoid tolerates low temperatures will be useful in evaluating its potential as a biological control agent of stored-product moths in temperate regions.     

Native UCP1 displays simple competitive kinetics between the regulators purine nucleotides and fatty acids

Elucidation of the regulation of uncoupling protein 1 (UCP1) activity in its native environment, i.e. the inner membrane of brown-fat mitochondria, has been hampered by the presence of UCP1-independent, quantitatively unresolved effects of investigated regulators on the brown-fat mitochondria themselves. Here we have utilized the availability of UCP1-ablated mice to dissect UCP1-dependent and UCP1-independent effects of regulators. Using a complex-I-linked substrate (pyruvate), we found that UCP1 can mediate a 4-fold increase in thermogenesis when stimulated with the classical positive regulator fatty acids (oleate). After demonstrating that the fatty acids act in their free form, we found that UCP1 increased fatty acid sensitivity approximately 30-fold (as compared with the 1.5-fold increase reported earlier based on nominal fatty acid values). By identifying the UCP1-mediated fraction of the response, we could conclude that the interaction between purine nucleotides (GDP) and fatty acids (oleate) unexpectedly displayed simple competitive kinetics. In GDP-inhibited mitochondria, oleate apparently acted as an activator. However, only a model in which UCP1 is inherently active (i.e."activating" fatty acids cannot be included in the model), where GDP functions as an inhibitor with a K(m) of 0.05 mm, and where oleate functions as a competitive antagonist for the GDP effect (with a K(i) of 5 nm) can fit all of the experimental data. We conclude that, when examined in its native environment, UCP1 functions as a proton (equivalent) carrier in the absence of exogenous or endogenous fatty acids.     

A novel evolutionary lineage of carbonic anhydrase (epsilon class) is a component of the carboxysome shell

A significant portion of the total carbon fixed in the biosphere is attributed to the autotrophic metabolism of prokaryotes. In cyanobacteria and many chemolithoautotrophic bacteria, CO(2) fixation is catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), most if not all of which is packaged in protein microcompartments called carboxysomes. These structures play an integral role in a cellular CO(2)-concentrating mechanism and are essential components for autotrophic growth. Here we report that the carboxysomal shell protein, CsoS3, from Halothiobacillus neapolitanus is a novel carbonic anhydrase (epsilon-class CA) that has an evolutionary lineage distinct from those previously recognized in animals, plants, and other prokaryotes. Functional CAs encoded by csoS3 homologues were also identified in the cyanobacteria Prochlorococcus sp. and Synechococcus sp., which dominate the oligotrophic oceans and are major contributors to primary productivity. The location of the carboxysomal CA in the shell suggests that it could supply the active sites of RuBisCO in the carboxysome with the high concentrations of CO(2) necessary for optimal RuBisCO activity and efficient carbon fixation in these prokaryotes, which are important contributors to the global carbon cycle.     

Carboxyatractyloside effects on brown-fat mitochondria imply that the adenine nucleotide translocator isoforms ANT1 and ANT2 may be responsible for basal and fatty-acid-induced uncoupling respectively

In brown-fat mitochondria, fatty acids induce thermogenic uncoupling through activation of UCP1 (uncoupling protein 1). However, even in brown-fat mitochondria from UCP1-/- mice, fatty-acid-induced uncoupling exists. In the present investigation, we used the inhibitor CAtr (carboxyatractyloside) to examine the involvement of the ANT (adenine nucleotide translocator) in the mediation of this UCP1-independent fatty-acid-induced uncoupling in brown-fat mitochondria. We found that the contribution of ANT to fatty-acid-induced uncoupling in UCP1-/- brown-fat mitochondria was minimal (whereas it was responsible for nearly half the fatty-acid-induced uncoupling in liver mitochondria). As compared with liver mitochondria, brown-fat mitochondria exhibit a relatively high (UCP1-independent) basal respiration ('proton leak'). Unexpectedly, a large fraction of this high basal respiration was sensitive to CAtr, whereas in liver mitochondria, basal respiration was CAtr-insensitive. Total ANT protein levels were similar in brown-fat mitochondria from wild-type mice and in liver mitochondria, but the level was increased in brown-fat mitochondria from UCP1-/- mice. However, in liver, only Ant2 mRNA was found, whereas in brown adipose tissue, Ant1 and Ant2 mRNA levels were equal. The data are therefore compatible with a tentative model in which the ANT2 isoform mediates fatty-acid-induced uncoupling, whereas the ANT1 isoform may mediate a significant part of the high basal proton leak in brown-fat mitochondria.