Non-Invasive In Vivo Imaging of Calcium Signaling in Mice

Rapid and transient elevations of Ca2+ within cellular microdomains play a critical role in the regulation of many signal transduction pathways. Described here is a genetic approach for non-invasive detection of localized Ca2+ concentration ([Ca2+]) rises in live animals using bioluminescence imaging (BLI). Transgenic mice conditionally expressing the Ca2+-sensitive bioluminescent reporter GFP-aequorin targeted to the mitochondrial matrix were studied in several experimental paradigms. Rapid [Ca2+] rises inside the mitochondrial matrix could be readily detected during single-twitch muscle contractions. Whole body patterns of [Ca2+] were monitored in freely moving mice and during epileptic seizures. Furthermore, variations in mitochondrial [Ca2+] correlated to behavioral components of the sleep/wake cycle were observed during prolonged whole body recordings of newborn mice. This non-invasive imaging technique opens new avenues for the analysis of Ca2+ signaling whenever whole body information in freely moving animals is desired, in particular during behavioral and developmental studies

Risk-taking, delay discounting, and time perspective in adolescent gamblers: an experimental study

Previous research has demonstrated that adult pathological gamblers (compared to controls) show risk-proneness, foreshortened time horizon, and preference for immediate rewards. No study has ever examined the interplay of these factors in adolescent gambling. A total of 104 adolescents took part in the research. Two equal-number groups of adolescent non-problem and problem gamblers, defined using the South Oaks Gambling Screen-Revised for Adolescents (SOGS-RA), were administered the Balloon Analogue Risk Task (BART), the Consideration of Future Consequences (CFC-14) Scale, and the Monetary Choice Questionnaire (MCQ). Adolescent problem gamblers were found to be more risk-prone, more oriented to the present, and to discount delay rewards more steeply than adolescent non-problem gamblers. Results of logistic regression analysis revealed that BART, MCQ, and CFC scores predicted gambling severity. These novel finding provides the first evidence of an association among problematic gambling, high risk-taking proneness, steep delay discounting, and foreshortened time horizon among adolescents. It may be that excessive gambling induces shortsighted behaviors that, in turn, facilitate gambling involvement

Molecular epidemiology of TT virus in Italy and phylogenesis of viral isolates from subjects at different risk for parenteral exposure

The prevalence and genotype distribution of human TT virus (TTV) in Italy were analysed in 593 subjects at different risk of parenteral infection who included blood donors, patients with chronic type C hepatitis (HCV), thalassemic patients, patients on haemodialysis, human immunodeficiency virus type 1 (HIV-1)-negative intravenous drug users (IVDUs), and HIV-1-infected subjects (IVDUs, heterosexual contacts and homosexual males). Plasma TTV-DNA was detected using nested PCR with primers deduced from the N22 region of the open reading frame 1 (ORF-1) and from the untranslated region (UTR) of the viral genome. Phylogenetic analysis of the sequences obtained from ORF-1 was also undertaken. A high prevalence of plasma TTV-DNA was observed using the UTR primers, with rates varying from 83-100% in the study groups. Using the N22 primers, HIV-1 positive IVDUs and homosexual males, haemodialysed patients and thalassemic patients had a significantly higher TTV prevalence (range: 23.0-86.1%) than blood donors, who displayed a high frequency of positivity (10.6%). Sequence analysis of 127 N22-positive isolates revealed that 42.5% were of type 1, 53.5% of type 2, 2.4% of type 3, and that two isolates (1.6%) were closely related to genotypes 1-2 but distinct from the other major genotypes. TTV-2 was significantly more prevalent in patients at high risk for parenteral infection and in HIV-1 positive homosexuals. In sequential samples from 15 TTV-infected subjects, N22 sequences were detectable persistently in 12 (80.0%) and UTR sequences persisted in all 15 patients over a mean period of 29.6 months. This data indicates that TTV is widespread in Italy in parenterally exposed subjects, and that the infection frequently persists

A trypanosomal orthologue of an intermembrane space chaperone has a non-canonical function in biogenesis of the single mitochondrial inner membrane protein translocase

Mitochondrial protein import is essential for Trypanosoma brucei across its life cycle and mediated by membrane-embedded heterooligomeric protein complexes, which mainly consist of trypanosomatid-specific subunits. However, trypanosomes contain orthologues of small Tim chaperones that escort hydrophobic proteins across the intermembrane space. Here we have experimentally analyzed three novel trypanosomal small Tim proteins, one of which contains only an incomplete Cx3C motif. RNAi-mediated ablation of TbERV1 shows that their import, as in other organisms, depends on the MIA pathway. Submitochondrial fractionation combined with immunoprecipitation and BN-PAGE reveals two pools of small Tim proteins: a soluble fraction forming 70 kDa complexes, consistent with hexamers and a second fraction that is tightly associated with the single trypanosomal TIM complex. RNAi-mediated ablation of the three proteins leads to a growth arrest and inhibits the formation of the TIM complex. In line with these findings, the changes in the mitochondrial proteome induced by ablation of one small Tim phenocopy the effects observed after ablation of TbTim17. Thus, the trypanosomal small Tims play an unexpected and essential role in the biogenesis of the single TIM complex, which for one of them is not linked to import of TbTim17