Ecological successions throughout the desiccation of Tirez lagoon (Spain) as an astrobiological time-analog for wet-to-dry transitions on Mars.

Tirez was a small and seasonal endorheic athalassohaline lagoon that was located in central Spain. In recent years, the lagoon has totally dried out, offering for the first time the opportunity to analyze its desiccation process as a "time-analog" to similar events occurred in paleolakes with varying salinity during the wet-to-dry transition on early Mars. On the martian cratered highlands, an early period of water ponding within enclosed basins evolved to a complete desiccation of the lakes, leading to deposition of evaporitic sequences during the Noachian and into the Late Hesperian.

Mineral paragenesis on Mars: The roles of reactive surface area and diffusion.

Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water-sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the transport of dissolved species may occur through the atmosphere-water and water-sediment interfaces. Here we present a suite of geochemical models designed to analyze the formation of secondary minerals in basaltic sediments on Mars, evaluating the role of (i) reactive surface areas and (ii) the transport of ions through a basalt sediment column.

The Argyre Region as a Prime Target for in situ Astrobiological Exploration of Mars.

At the time before ∼3.5 Ga that life originated and began to spread on Earth, Mars was a wetter and more geologically dynamic planet than it is today. The Argyre basin, in the southern cratered highlands of Mars, formed from a giant impact at ∼3.

Tracking the weathering of basalts on Mars using lithium isotope fractionation models.

Lithium (Li), the lightest of the alkali elements, has geochemical properties that include high aqueous solubility (Li is the most fluid mobile element) and high relative abundance in basalt-forming minerals (values ranking between 0.2 and 12 ppm). Li isotopes are particularly subject to fractionation because the two stable isotopes of lithium-Li and Li-have a large relative mass difference (∼15%) that results in significant fractionation between water and solid phases.

Astrobiology through the ages of Mars: the study of terrestrial analogues to understand the habitability of Mars.

Mars has undergone three main climatic stages throughout its geological history, beginning with a water-rich epoch, followed by a cold and semi-arid era, and transitioning into present-day arid and very cold desert conditions. These global climatic eras also represent three different stages of planetary habitability: an early, potentially habitable stage when the basic requisites for life as we know it were present (liquid water and energy); an intermediate extreme stage, when liquid solutions became scarce or very challenging for life; and the most recent stage during which conditions on the surface have been largely uninhabitable, except perhaps in some isolated niches. Our understanding of the evolution of Mars is now sufficient to assign specific terrestrial environments to each of these periods.

Noachian and more recent phyllosilicates in impact craters on Mars.

Hundreds of impact craters on Mars contain diverse phyllosilicates, interpreted as excavation products of preexisting subsurface deposits following impact and crater formation. This has been used to argue that the conditions conducive to phyllosilicate synthesis, which require the presence of abundant and long-lasting liquid water, were only met early in the history of the planet, during the Noachian period (> 3.6 Gy ago), and that aqueous environments were widespread then.

Systemic and local effects of angiotensin II blockade in experimental diabetic nephropathy.

Introduction: Our objective was to evaluate the effect of blocking the renin-angiotensin system (RAS) on the expression of transforming growth factor-beta 1 (TGF-beta1), platelet derived growth factor-B (PDGF-B), tumour necrosis factor-alpha (TNF-alpha) and vascular endothelial growth factor (VEGF) in diabetic kidney glomeruli.

Materials And Method: 1) Uninephrectomised streptozotocin induced diabetic rats were treated during eight months with vehicle (CD) or irbesartan (ID). Uninephrectomised non-diabetic rats were used as control group (ND).