Glucoamylase isoform (GAII) purified from a thermophilic fungus Scytalidium thermophilum 15.8 with biotechnological potential

Scytalidium thermophilum 15.8 produced two extracellular glucoamylases. Using a DEAE-Cellulose chromatographic column glucoamylases form II (GAII) was separated and purified from glucoamylases form I (GAI) that was previously purified and characterised (Cereia et al., 2000) when the filtrate of the culture medium was applied to a DEAE-Cellulose chromatographic column. GAII bound to the DEAECellulose and was eluted with a NaCl gradient, while GAI did not bind to the resin. GAII presentedelectrophoretic homogeneity in 6% denaturing and non-denaturing PAGE, separately, with a molecular mass of 83 kDa, after the second round DEAE-Cellulose purification step. The enzyme pI was 7.2.Optima pH and activity temperature were 5.5 and 55ºC respectively for starch and maltose as substrates, with a termostability of 2.5 min at 60ºC. Enzymatic activities were activated by 1 mM Na+, Mn2+ and Mg2+ or 10 mM NH4+, Ba2+ and Mg2+. The carbohydrate content was 10%. The kinetic parameters Km and Vmax with starch and maltose as substrate were 0.2 and 1.5 mg/ml, and 22.3 and 4.39 U/mg of protein, respectively. The amino acid sequence of GAII had 92% homology with theglucoamylase of Humicola grisea var. thermoidea after 13 cycles. Generally, GAII had different properties compared with GAI (Cereia et al., 2000)

A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

Effects of Heat-shock On the Level of Trehalose and Glycogen, and On the Induction of Thermotolerance in Neurospora-crassa

Neurospora crassa conidiospore germlings exposed to a heat shock (30-45-degrees-C) rapidly accumulated trehalose and degraded glycogen, even in the presence of cycloheximide. This phenomenon was also rapidly reversible upon return of the cells at 30-degrees-C. Trehalose accumulation at 45-degrees-C demanded an exogenous source of carbon and either glucose or glycerol fulfilled such requirement. Experiments with the cyclic AMP-deficient cr-l mutant suggested that the effects of temperature shifts on trehalose level were independent of cAMP metabolism. Cells exposed at 45-degrees-C under conditions permissive for trehalose accumulation (i.e. in the presence of an assimilable carbon source) also acquired thermotolerance