Nocturnal line transect sampling of wild boar (Sus scrofa) in a Mediterranean forest: long-term comparison with capture–mark–resight population estimates

Although accurate estimates of wild boar (Sus scrofa) populations are crucial for any effective resource management or pest control programme, this species is well-known to be difficult to monitor. We conducted a 10-year study in a fenced Mediterranean forest (Rome, Italy) to evaluate nocturnal line transect sampling performances. We focused on its accuracy in monitoring changes in density, which was independently estimated by capture–mark–resight (CMR) performed on counts at feeding sites. We carried out night surveys in the autumn of 2001–2010, using portable infrared cameras to detect animals. We sampled on foot to cover the whole study area and the different habitat types evenly. However, to ensure safe working conditions during night and to limit disturbance, we placed transects along paths and forest roads. Therefore, we investigated the potential impact of our convenience sampling on the detection process, using radiolocations of wild boars to assess their distribution with respect to selected transects. We found that our survey design should not have biased our estimates and that densities and coefficients of variations from line transect sampling were consistent with CMR results. Although labour-intensive, we believe that our approach can improve wild boar monitoring effectively, even in concealing habitats, providing decision makers with accurate estimates (and quantified confidence limits) which can help to develop the most appropriate management programme. Moreover, the current low price of new-generation infrared cameras can also increase strongly the cost-effectiveness of this method.     

Fungal biomass production in response to elevated atmospheric CO2 in a Glomus mosseae–Prunus cerasifera model system

Biomass and length of intraradical and extraradical mycorrhizal mycelium under ambient (aCO₂) and elevated (eCO₂ ) atmospheric CO₂ was investigated using a non-destructive in vivo experimental model system. Time-course experiments allowed measurements of intact extraradical mycelium spreading from mycorrhizal roots of Prunus cerasifera micropropagated plants inoculated with the arbuscular mycorrhizal fungus Glomus mosseae, in controlled environmental chambers. The length of extraradical mycelium was significantly increased at the highest CO₂ concentration, ranging from 10.7 to 20.3 m at aCO₂ and eCO₂, respectively. The biochemical determination of mycelial glucosamine content allowed the evaluation of intraradical and extraradical fungal biomass, which were 2 and 3 times larger at eCO₂ than at aCO₂. Present data show that Glomus mosseae responds to increases of CO₂ concentrations producing larger mycorrhizal networks which may potentially represent carbon sink agents in soil ecosystems.     

The p38 MAPK-MK2 Axis Regulates E2F1 and FOXM1 Expression after Epirubicin Treatment

E2F1 is responsible for the regulation of FOXM1 expression, which plays a key role in epirubicin resistance. Here, we examined the role and regulation of E2F1 in response to epirubicin in cancer cells. We first showed that E2F1 plays a key role in promoting FOXM1 expression, cell survival, and epirubicin resistance as its depletion by siRNA attenuated FOXM1 induction and cell viability in response to epirubicin. We also found that the p38-MAPK activity mirrors the expression patterns of E2F1 and FOXM1 in both epirubicin-sensitive and -resistant MCF-7 breast cancer cells, suggesting that p38 has a role in regulating E2F1 expression and epirubicin resistance. Consistently, studies using pharmacologic inhibitors, siRNA knockdown, and knockout mouse embryonic fibroblasts (MEF) revealed that p38 mediates the E2F1 induction by epirubicin and that the induction of E2F1 by p38 is, in turn, mediated through its downstream kinase MK2 [mitogen-activated protein kinase (MAPK)-activated protein kinase 2; MAPKAPK2]. In agreement, in vitro phosphorylation assays showed that MK2 can directly phosphorylate E2F1 at Ser-364. Transfection assays also showed that E2F1 phosphorylation at Ser-364 participates in its induction by epirubicin but also suggests that other phosphorylation events are also involved. In addition, the p38-MK2 axis can also limit c-jun-NH(2)-kinase (JNK) induction by epirubicin and, notably, JNK represses FOXM1 expression. Collectively, these findings underscore the importance of p38-MK2 signaling in the control of E2F1 and FOXM1 expression as well as epirubicin sensitivity. Mol Cancer Res; 10(9); 1189-202. ?2012 AACR.     

Loss of Prohibitin Membrane Scaffolds Impairs Mitochondrial Architecture and Leads to Tau Hyperphosphorylation and Neurodegeneration

Fusion and fission of mitochondria maintain the functional integrity of mitochondria and protect against neurodegeneration, but how mitochondrial dysfunctions trigger neuronal loss remains ill-defined. Prohibitins form large ring complexes in the inner membrane that are composed of PHB1 and PHB2 subunits and are thought to function as membrane scaffolds. In Caenorhabditis elegans, prohibitin genes affect aging by moderating fat metabolism and energy production. Knockdown experiments in mammalian cells link the function of prohibitins to membrane fusion, as they were found to stabilize the dynamin-like GTPase OPA1 (optic atrophy 1), which mediates mitochondrial inner membrane fusion and cristae morphogenesis. Mutations in OPA1 are associated with dominant optic atrophy characterized by the progressive loss of retinal ganglion cells, highlighting the importance of OPA1 function in neurons. Here, we show that neuron-specific inactivation of Phb2 in the mouse forebrain causes extensive neurodegeneration associated with behavioral impairments and cognitive deficiencies. We observe early onset tau hyperphosphorylation and filament formation in the hippocampus, demonstrating a direct link between mitochondrial defects and tau pathology. Loss of PHB2 impairs the stability of OPA1, affects mitochondrial ultrastructure, and induces the perinuclear clustering of mitochondria in hippocampal neurons. A destabilization of the mitochondrial genome and respiratory deficiencies manifest in aged neurons only, while the appearance of mitochondrial morphology defects correlates with tau hyperphosphorylation in the absence of PHB2. These results establish an essential role of prohibitin complexes for neuronal survival in vivo and demonstrate that OPA1 stability, mitochondrial fusion, and the maintenance of the mitochondrial genome in neurons depend on these scaffolding proteins. Moreover, our findings establish prohibitin-deficient mice as a novel genetic model for tau pathologies caused by a dysfunction of mitochondria and raise the possibility that tau pathologies are associated with other neurodegenerative disorders caused by deficiencies in mitochondrial dynamics.     

A pathogenic mechanism in Huntington's disease involves small CAG-repeated RNAs with neurotoxic activity

Huntington's disease (HD) is an autosomal dominantly inherited disorder caused by the expansion of CAG repeats in the Huntingtin (HTT) gene. The abnormally extended polyglutamine in the HTT protein encoded by the CAG repeats has toxic effects. Here, we provide evidence to support that the mutant HTT CAG repeats interfere with cell viability at the RNA level. In human neuronal cells, expanded HTT exon-1 mRNA with CAG repeat lengths above the threshold for complete penetrance (40 or greater) induced cell death and increased levels of small CAG-repeated RNAs (sCAGs), of ≈21 nucleotides in a Dicer-dependent manner. The severity of the toxic effect of HTT mRNA and sCAG generation correlated with CAG expansion length. Small RNAs obtained from cells expressing mutant HTT and from HD human brains significantly decreased neuronal viability, in an Ago2-dependent mechanism. In both cases, the use of anti-miRs specific for sCAGs efficiently blocked the toxic effect, supporting a key role of sCAGs in HTT-mediated toxicity. Luciferase-reporter assays showed that expanded HTT silences the expression of CTG-containing genes that are down-regulated in HD. These results suggest a possible link between HD and sCAG expression with an aberrant activation of the siRNA/miRNA gene silencing machinery, which may trigger a detrimental response. The identification of the specific cellular processes affected by sCAGs may provide insights into the pathogenic mechanisms underlying HD, offering opportunities to develop new therapeutic approaches.     

Polyfunctional Type-1, -2, and -17 CD8+ T Cell Responses to Apoptotic Self-Antigens Correlate with the Chronic Evolution of Hepatitis C Virus Infection

Caspase-dependent cleavage of antigens associated with apoptotic cells plays a prominent role in the generation of CD8⁺ T cell responses in various infectious diseases. We found that the emergence of a large population of autoreactive CD8⁺ T effector cells specific for apoptotic T cell-associated self-epitopes exceeds the antiviral responses in patients with acute hepatitis C virus infection. Importantly, they endow mixed polyfunctional type-1, type-2 and type-17 responses and correlate with the chronic progression of infection. This evolution is related to the selection of autoreactive CD8⁺ T cells with higher T cell receptor avidity, whereas those with lower avidity undergo prompt contraction in patients who clear infection. These findings demonstrate a previously undescribed strict link between the emergence of high frequencies of mixed autoreactive CD8⁺ T cells producing a broad array of cytokines (IFN-γ, IL-17, IL-4, IL-2…) and the progression toward chronic disease in a human model of acute infection.     

Synthesis and biological evaluation of a new class of glycoconjugated disulfides that exhibit potential anticancer properties

A synthetic strategy, based on the in situ generation of sulfenic acids and their thermolysis in the presence of thiols, was developed for obtaining a collection of polyvalent disulfides in which a benzene scaffold accommodates two or three flexible arms connecting saccharide moieties. Targeting carbohydrate metabolism or carbohydrate-binding proteins may constitute important approaches in the discovery process of new therapeutic anticancer agents. Therefore, a preliminary screening to ascertain the cytostatic/cytotoxic potential of this new class of enantiopure glycoconjugated disulfides has been conducted. Among them, products with two disulfide arms, harbouring galactose rings, induced high levels of apoptosis on U937 histiocytic lymphoma cells, but lower levels of cell death on peripheral blood mononuclear cells from healthy donors. Further experiments indicated that apoptosis induced by these glycoconjugated bis(disulfides) in U937 cells corresponds to the Bcl-2-sensitive, intrinsic form of apoptotic cell death. The bioinvestigation was extended to a panel of human cancer cell lines with different levels of malignancy and resistance to chemotherapeutic agents. Compounds under study proved to induce detectable levels of cell death towards all the tested cancer cell lines.