Occurrence of Tuber melanosporum in relation to soil surface layer properties and soil differentiation

An intensive survey was carried out on a 12-year-old experimental truffle bed of Tuber melanosporum Vitt. located in the central Apennines. The aim of the investigation was to relate the presence and carpophore production of T. melanosporum to changes in soil structure, aeration and fertility — expressed in terms of 0.25–2.00 mm aggregate fraction, total organic carbon, DTPA-extractable Mn and host plant height — and to determine if these modifications, whenever present, could be ascribed to soil differentiation within the truffle bed. The occurrence of pianelli — i.e. areas with little herbaceous ground cover created by T. melanosporum — showed a close relationship with host plant height and aeration of soil surface layers. Where pianelli occurred, the height of symbiont trees increased and the content of reduced Mn, indicating the presence of a well-aerated soil environment, decreased. The variation of host plant height was attributable not only to the increased absorption of nutrients related to the ectomycorrhizal partnership, but also to soil differentiation. The soils of the investigated area were characterized by a relatively low slope gradient, a rigid framework of gravel and a homogeneous physico-chemical behaviour, due to the predominance of Ca among exchangeable bases. In these environmental conditions, T. melanosporum was present in the rather thick soil belonging to Typic Rendolls, whereas it was absent in the area characterized by thin Lithic Rendolls. In the latter case, the plant cover was probably too scarce to protect T. melanosporum from summer dryness, and consequently the more resistant T. aestivum species prevailed. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Penicillium echinulatum Secretome on Sugar Cane Bagasse

Plant feedstocks are at the leading front of the biofuel industry based on the potential to promote economical, social and environmental development worldwide through sustainable scenarios related to energy production. Penicillium echinulatum is a promising strain for the bioethanol industry based on its capacity to produce large amounts of cellulases at low cost. The secretome profile of P. echinulatum after grown on integral sugarcane bagasse, microcrystalline cellulose and three types of pretreated sugarcane bagasse was evaluated using shotgun proteomics. The comprehensive chemical characterization of the biomass used as the source of fungal nutrition, as well as biochemical activity assays using a collection of natural polysaccharides, were also performed. Our study revealed that the enzymatic repertoire of P. echinulatum is geared mainly toward producing enzymes from the cellulose complex (endogluganases, cellobiohydrolases and β-glucosidases). Glycoside hydrolase (GH) family members, important to biomass-to-biofuels conversion strategies, were identified, including endoglucanases GH5, 7, 6, 12, 17 and 61, β-glycosidase GH3, xylanases GH10 and GH11, as well as debranching hemicellulases from GH43, GH62 and CE2 and pectinanes from GH28. Collectively, the approach conducted in this study gave new insights on the better comprehension of the composition and degradation capability of an industrial cellulolytic strain, from which a number of applied technologies, such as biofuel production, can be generated.     

Osmotic and ionic effects of NaCl and Na2SO4 salinity on Phragmites australis

Osmotic and ion-specific effects of NaCl and Na₂SO₄ on Phragmites australis (Cav.) Trin ex. Steud. were investigated in a laboratory experiment by examining effects of iso-osmotic solutions of NaCl and Na₂SO₄ on growth, osmolality of cell sap, proline content, elemental composition and gas exchange. Plants were supplied with a control standard nutrient solution (Ψ = −0.09 MPa) or solutions of NaCl or Na₂SO₄ at water potentials of −0.50, −1.09 or −1.74 MPa. Salt treatments increased root concentrations of Na and S or Cl, whereas P. australis had efficient mechanisms for exclusion of Na and S and partly Cl ions from the leaves. Incomplete exclusion of Cl from the leaves may affect aboveground biomass production, which was significantly more reduced by NaCl than Na₂SO₄. Stomatal conductance was negatively influenced by decreasing water potentials caused by NaCl or Na₂SO₄, implying that a non-significant photosynthetic depression observed in plants grown at −1.74 MPa was mainly due to osmotically induced stomatal closure. This was supported by decreasing internal CO₂ concentrations. Saline conditions increased the intrinsic water use efficiency and did not alter photosynthetic parameters derived from light response curves, supporting the assumption of a well-functioning CO₂ utilization in salt stressed plants. The leaf proline concentration increased equally in NaCl and Na₂SO₄-treated plants, and may play an important role as a compatible organic solute. P. australis possesses a range of mechanisms conferring tolerance to both NaCl and Na₂SO₄ stress and except in terms of growth the phytotoxicity of NaCl and Na₂SO₄ are comparable.     

Strongly female‐biased sex allocation in a trivoltine population of Trypoxylon (Trypargilum) opacum Brèthes (Hymenoptera,Crabronidae)

Buschini, M.L.T. and Bergamaschi, A.C.B. 2009. Strongly female‐biased sex allocation in a trivoltine population of Trypoxylon (Trypargilum) opacum Brèthes (Hymenoptera, Crabronidae). —Acta Zoologica (Stockholm) 91 : 433–439. This study was carried in southern Brazil from December 2001 to December 2004. The aim of this paper is to provide additional information on the life‐history and sex allocation of this little known species. This wasp’s species has two alternative life histories: either they pupated immediately and emerged as adults later in the same season (direct development) or they entered diapause, overwintering and pupating the following spring (delayed development). The numerical sex ratio of overwintering and of direct developing wasps were strongly female biased in 2002, 2003 and 2004.     

Fibroblasts from the muscles of Duchenne muscular dystrophy patients are resistant to cell detachment apoptosis

Extracellular matrix (ECM) proteins, including collagen and growth factors, are greatly increased in tissue fibrosis and mainly secreted by fibroblasts. We previously demonstrated that muscle-derived fibroblasts from Duchenne muscular dystrophy (DMD) patients have a profibrotic phenotype, that includes significantly reduced expression of tissue inhibitor of metalloprotease 3 (TIMP-3) compared to control. Since TIMP-3 induces apoptosis in various cell types, we hypothesized increased resistance of DMD fibroblasts to apoptosis. To address this, we evaluated apoptotic nuclei, caspase 3, caspase 3 substrate expression, and migration and adhesion properties of muscle-derived fibroblasts, after applying different apoptosis-inducing treatments. We found that DMD fibroblasts were less susceptible to cell death, more adhesive, and had greater tendency to migrate than control fibroblasts — findings further supported by alterations in FAK and ERK/MAPK expression. Resistance to apoptosis and greater adhesion are likely to contribute to muscle fibrosis so a pharmacological treatment that targets dysregulated pathways involved in cell detachment apoptosis (anoikis) may limit the progressive fibrotic remodeling characteristic of DMD.     

HDAC8 regulates canonical Wnt pathway to promote differentiation in skeletal muscles

Histone deacetylase 8 (HDAC8) is a class 1 histone deacetylase and a member of the cohesin complex. HDAC8 is expressed in smooth muscles, but its expression in skeletal muscle has not been described. We have shown for the first time that HDAC8 is expressed in human and zebrafish skeletal muscles. Using RD/12 and RD/18 rhabdomyosarcoma cells with low and high differentiation potency, respectively, we highlighted a specific correlation with HDAC8 expression and an advanced stage of muscle differentiation. We inhibited HDAC8 activity through a specific PCI-34051 inhibitor in murine C2C12 myoblasts and zebrafish embryos, and we observed skeletal muscles differentiation impairment. We also found a positive regulation of the canonical Wnt signaling by HDAC8 that might explain muscle differentiation defects. These findings suggest a novel mechanism through which HDAC8 expression, in a specific time window of skeletal muscle development, positively regulates canonical Wnt pathway that is necessary for muscle differentiation.     

Habitat but not group size or recent predator activity affect corvid collective vigilance at carcasses

Vigilance is an important anti-predator behaviour that can be an indicator of the predation risk faced by potential prey animals. Here, we assess the collective vigilance, or the vigilance level of an entire group, of corvids (Family: Corvidae) at experimentally placed carcasses in a desert environment in Australia. Specifically, we explore the relationship between collective vigilance levels and the habitat in which the carcass was placed, the time since a potential predator (dingo Canis dingo, wedge-tailed eagle Aquila audax or red fox Vulpes vulpes) was present at a carcass, and the group size of corvids around the carcass. We found that corvids are more vigilant in open habitat, but that group size and the recent presence of a potential predator does not affect the collective vigilance behaviour of corvids. The results demonstrate the important link between habitat and vigilance, and that animals may adopt anti-predator behaviours irrespective of the size of the group in which they occur or the recent presence of a potential predator.