Characterization and assessment of new fibrillar collagen inks and bioinks for 3D printing and bioprinting.

Collagen is a cornerstone protein for tissue engineering and 3D bioprinting due to its outstanding biocompatibility, low immunogenicity, and natural abundance in human tissues. Nonetheless, it still poses some important challenges, such as complicated and limited extraction processes, usually accompanied by batch- to-batch reproducibility and influence of factors, such as temperature, pH, and ionic strength. In this work, we evaluated the suitability and performance of new, fibrillar type I collagen as standardized and reproducible collagen source for 3D printing and bioprinting. The acidic, native fibrous collagen formulation (5% w/w) performed remarkably during 3D printing, which was possible to print constructs of up to 27 layers without collapsing. On the other hand, the fibrous collagen mass has been modified to provide a fast, reliable, and easily neutralizable process. The neutralization with TRIS-HCl enabled the inclusion of cells without hindering printability. The cell-laden constructs were printed under mild conditions (50-80 kPa, pneumatic 3D printing), providing remarkable cellular viability (>90%) as well as a stable platform for cell growth and proliferation in vitro. Therefore, the native, type I collagen masses characterized in this work offer a reproducible and reliable source of collagen for 3D printing and bioprinting purposes.

Bird species in Mediterranean pine plantations exhibit different characteristics to those in natural reforested woodlands.

Passive woodland regeneration following cropland abandonment and pine plantations are two major approaches for vegetation restoration in agricultural landscapes in the Mediterranean Basin. We compared the effects of these two contrasting approaches on local bird density in central Spain on the basis of species characteristics, including regional density, habitat breadth, life-history traits and plumage colouration. Local bird density increased with regional density and habitat breadth in both woodland and pine plantation plots following macroecological patterns of bird abundance and distribution. In woodlands, dichromatic species were more abundant than monochromatic species and bird density increased with the intensity of territory defense and as the proportion of plumage colour generated by pheomelanin decreased. Contrary to our prediction, this latter observation suggests that woodlands may induce higher levels of physiological stress in birds than pine plantations even though these represent a novel habitat change. In pine plantations, sedentary species were more abundant than migratory species and bird density was negatively related to body and egg mass. These traits of bird species in pine plantations are characteristic of successful invaders. The variation in bird density explained by phylogeny was twice as high in pine plantations as in woodlands, suggesting that pine plantations limit accessibility to some clades. Our results support, from an evolutionary perspective, the described inability of pine plantations on cropland to maintain or increase bird diversity in Mediterranean agricultural landscapes.

Identifying areas of high herpetofauna diversity that are threatened by planned infrastructure projects in Spain.

A major task related to conservation is to predict if planned infrastructure projects are likely to threaten biodiversity. In this study we investigated the potential impact of planned infrastructure in Spain on amphibian and reptile species, two highly vulnerable groups given their limited dispersal and current situation of population decline. We used distribution data of both groups to identify areas of high herpetofauna diversity, and compared the locations of these areas with the locations of the planned road, high-speed train railway and water reservoir network. Four criteria were used for this identification: species richness, rarity, vulnerability, and a combined index of the three criteria. From a total of 1441 cells of 20 x 20 km, areas of high diversity were defined as those cells whose ranked values for the different criteria included either all species or all threatened species. The combined index provided the smallest number of cells needed to retain all threatened species (1.7 and 2.6% of the cells for amphibian and reptile species, respectively). Coincidences between these high diversity areas and cells including planned infrastructures-denominated 'alert planning units'-were 35.4% for amphibians and 31.2% for reptiles. Mitigation of the potential impacts would include actions such as barriers to animal access to roads and railways and ecoducts under these constructions. Our approach provides conservation authorities information that can be used to make decisions on habitat protection. A technique that identifies threats to herpetofauna before they occur is also likely to improve the chance of herpetofauna being protected.