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The mechanical properties of the extracellular matrix (ECM) determine cell differentiation, proliferation and migration through mechanoresponsive proteins including YAP. However, how different mechanical signals cooperate, synergize or compete to steer cell behavior remains poorly understood. Here, we have examined competition between the two major ECM mechanical cues, i.e. rigidity, which activates cell mechanosensing, and viscous energy dissipation, which reduces stiffness blunting cell mechanotransduction. To trigger competition, we have engineered protein hydrogels allowing concomitant modulation of stiffness and viscosity by mechanisms characteristic of native ECM. Culturing cells on these hydrogels, we have found that substrate energy dissipation attenuates YAP mechanosensing prevailing over stiffness cues. Hampered YAP activation on more dissipative substrates correlates with faster actin flow and smaller focal adhesions. Mechanistically, inhibition of actomyosin contractility reverses the outcome of the competition between rigidity and energy dissipation. Our results highlight the dominating contribution of substrate viscosity to the biology of the cell.

The use of farm dairy effluents (FDE) has become a promising alternative to increase pasture yield while reducing the environmental impact of waste accumulation into streams, but other environmental implications should be considered. The present study aimed to assess the effect of application of either raw FDE or lagoon-stored FDE compared to dissolved urea or a non-amended control on N2O emission, soil N dynamics, functional microbial activity, and the yield and N-use efficiency of a fescue pasture. The normalized N application rate of 200 kg N ha−1 was divided into four seasonal events in a greenhouse experiment. Similar fescue forage production with FDE or urea positioned FDE application to soil as an alternative disposal. The repeated application of raw effluent delivered more organic C to the soil which induced an increase in enzyme activities, a shift in the catabolic activity of the soil microbial community, and greater N mineralization potential. On the other hand, urea addition decreased the functional activity of the soil microbial community. However, N2O emissions were greater for the raw effluent, so lagoon-stored effluent is an alternative to manage FDE under these conditions, avoiding urea addition and enhancing soil metabolic activity.

Arbuscular mycorrhizas (AM) are particularly relevant in grasslands due to the high colonization in grasses, main constituent of this ecosystem. Natural grassland (NG) is the dominant ecosystem of Uruguay and it supports one of the main economic activities of the country: livestock. Available phosphorus (P) contents in NG soils of Uruguay are low, so phosphate fertilization is frequent. The aim of this work was to study the effect of phosphorus fertilization on arbuscular mycorrhizal fungi (AMF) diversity of two native grasses of Uruguay:Paspalum dilatatum and Coelorhachis selloana. Diversity and abundance of AMF spores in the rhizosphere of grasses were studied using morphological techniques, while AMF diversity in roots was studied through T-RFLP. The study was conducted in a long-term experiment of phosphorus fertilization in Uruguayan grasslands.The increase in available P did not affect the diversity of AMF in the roots or in the rhizosphere of the studied grasses. The richness of AMF biotypes in roots and spores abundance differed between host species, with higher values in C. selloana than in P. dilatatum. Differences in AMF diversity between seasons were observed, with greater number of biotypes in winter than in summer.

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