Biology subjects

Costa, L.

Publications and source records attributed to Costa, L..

20 records · Page 2Linked to original sources

bioRxiv2019

Genetic Diversity and Phylogenetic Relationships of Annual and Perennial Glycine Species

We estimated average genetic diversity of two Glycine annual and six perennial species based upon 76 orthologous gene sets and performed phylogenetic analysis, divergence analysis and tests for departure from neutrality of the eight species using 52 orthologous gene sets. In addition, 367 orthologous gene sets were used to estimate the relationships of 11 G. canescens accessions. Among the perennials, G. canescens showed the highest nucleotide diversity and the other perennials except G. tomentella had higher nucleotide diversity than the two annuals. Phylogenetic analysis of the Glycine showed a similar genome grouping with the previous report except G. cyrtoloba and G. stenophita formed a sister clade in the study. Divergence analysis supported the phylogenetic relationships, G. falcata was the most divergent from G. max, followed by G. cyrtoloba, G. syndetika, G. tomentella D3, G. stenophita and G. canescens. Neutrality selection tests within species showed that most genes were subjected to a recent directional selection due to a selective sweep or rapid population expansion. Although most gene sequence had negative and significant Tajimas D, the sequences were homogeneous in the levels of polymorphism and divergence between G. max and other Glycine species based on the HKA test, thus, Glycine perennials may have experienced very similar evolutionary selection as inferred by trans-specific mutation analysis. The greater genetic diversity of most perennial Glycine species and their origins from the warmer and drier climates of Australia suggested the perennials as potential sources of heat and drought resistance that will be of value in the face of climate change.

genetics↗

bioRxiv2018

Quantitative Mapping of Free-Standing Lipid Membranes on Nano-Porous Mica Substrates

The physic-chemistry of biological membranes is at the origin of fundamental cellular functions such as vesicle trafficking, cell adhesion and migration1-3. Because most of intracellular shapes and local demixing of membranes take place in the nanometer scale, AFM becomes an extremely powerful technique to assess the properties of these biological membranes. Porous substrates provide an elegant strategy to avoid the conundrum of placing soft and thin biomembranes on hard substrates for AFM studies, although the surface chemistry make the actual substrates rather challenging setups. Here, we have engineered porous systems on the most widely used substrate in AFM, mica muscovite, with tunable pore sizes from some tens to few hundreds nanometers for biological applications. We show that free-standing bilayers on nano-porous can be obtained by using well-established vesicle spreading methods and that they display equivalent nano-mechanical stability and phsyco-chemical properties to that of membranes on conventional mica supports. By reducing the pore radius < 40 nm and limiting the contribution of membrane tension to the elastic response of free-standing membranes we estimate a bending modulus of 18 kbT and 73 kbT for DOPC and DPPC bilayers, respectively. The quantitative mapping of suspended membranes shows a different mechanical response at the pore rims, which is more pronounced for DPPC and suggest a different lipid ordering. We find that the combination of membrane bending and the different lipid packing at the edges of pores shapes the curvature of free-standing membranes on pores in the range of few tens of nm.

biophysics↗