Search bioRxivSearch

Biology subjects

Visconti, P.

Publications and source records attributed to Visconti, P..

2 recordsLinked to original sources

Putting species back on the map: devising a robust method for quantifying the biodiversity impacts of land conversion

AimQuantifying connections between the global drivers of habitat loss and biodiversity impact is vital for decision-makers promoting responsible land-use. To that end, biodiversity impact metrics should be able to report linked trends in specific anthropogenic activities and changes in biodiversity state. However, for biodiversity, it is challenging to deliver integrated information on its multiple dimensions (i.e. species richness, endemicity) and keep it practical. Here, we developed a biodiversity footprint indicator that can i) capture the status of different species groups, ii) link biodiversity impact to specific human activities, and iii) be adapted to the most applicable scale for the decision context.\n\nLocationCerrado Biome, Brazil\n\nMethodsWe illustrate this globally-applicable approach for the case of soybean expansion in the Brazilian Cerrado. Using species-specific habitat suitability models, we assessed the impact of soy expansion and other land uses over 2,000 species of amphibians, birds, mammals and plants for three time periods between 2000 and 2014.\n\nResultsOverall, plants suffered the greatest reduction of suitable habitat. However, among endemic and near-endemic species - which face greatest risk of global extinction from habitat conversion in the Cerrado - birds were the most affected group. While planted pastures and cropland expansion were together responsible for most of the absolute biodiversity footprint, soy expansion via direct conversion of natural vegetation had the greatest impact per unit area. The total biodiversity footprint over the period was concentrated in the southern states of Minas Gerais, Goias and Mato Grosso, but the soy footprint was proportionally higher in those northern states (such as Bahia and Piaui) which belong to the new agricultural frontier.\n\nMain conclusionsThe ability and flexibility of our approach to examine linkages between biodiversity loss and specific human activities has substantial potential to better characterise the pathways by which habitat loss drivers operate.

ecology

The actin cytoskeleton of the mouse sperm flagellum is organized in a helical structure

Conception of a new mammalian organism is determined by the fusion of a sperm cell with an oocyte during fertilization. Motility is one of the features of sperm that allows them to succeed in fertilization, and their flagellum is essential for this function. Longitudinally, the flagellum divides into the midpiece, the principal piece, and the end piece. A precise cytoskeletal architecture of the sperm tail is key for the acquisition of fertilization competence. It has been proposed that the actin cytoskeleton plays essential roles in the regulation of sperm motility, however, actin organization in sperm remains elusive. In the present work, we found different types of actin structures in the sperm tail, using stochastic optical reconstruction microscopy (STORM). In the principal piece, actin is radially distributed between the axoneme and the plasma membrane. The actin-associated proteins spectrin and adducin are also found in these structures. Strikingly, polymerized actin in the midpiece forms a double-helix that accompanies mitochondria. Our findings illustrate a novel specialized structure of actin filaments in a mammalian cell.

cell biology