Geogenetic patterns in mouse lemurs (genus Microcebus) reveal the ghosts of Madagascar's forests past.

Phylogeographic analysis can be described as the study of the geological and climatological processes that have produced contemporary geographic distributions of populations and species. Here, we attempt to understand how the dynamic process of landscape change on Madagascar has shaped the distribution of a targeted clade of mouse lemurs (genus Microcebus) and, conversely, how phylogenetic and population genetic patterns in these small primates can reciprocally advance our understanding of Madagascar's prehuman environment. The degree to which human activity has impacted the natural plant communities of Madagascar is of critical and enduring interest. Today, the eastern rainforests are separated from the dry deciduous forests of the west by a large expanse of presumed anthropogenic grassland savanna, dominated by the Family Poaceae, that blankets most of the Central Highlands. Although there is firm consensus that anthropogenic activities have transformed the original vegetation through agricultural and pastoral practices, the degree to which closed-canopy forest extended from the east to the west remains debated. Phylogenetic and population genetic patterns in a five-species clade of mouse lemurs suggest that longitudinal dispersal across the island was readily achieved throughout the Pleistocene, apparently ending at ∼55 ka. By examining patterns of both inter- and intraspecific genetic diversity in mouse lemur species found in the eastern, western, and Central Highland zones, we conclude that the natural environment of the Central Highlands would have been mosaic, consisting of a matrix of wooded savanna that formed a transitional zone between the extremes of humid eastern and dry western forest types

Pedigree-based and phylogenetic methods support surprising patterns of mutation rate and spectrum in the gray mouse lemur

Mutations are the raw material on which evolution acts, and knowledge of their frequency and genomic distribution is crucial for understanding how evolution operates at both long and short timescales. At present, the rate and spectrum of de novo mutations have been directly characterized in relatively few lineages. Our study provides the first direct mutation-rate estimate for a strepsirrhine (i.e., the lemurs and lorises), which comprises nearly half of the primate clade. Using high-coverage linked-read sequencing for a focal quartet of gray mouse lemurs (Microcebus murinus), we estimated the mutation rate to be among the highest calculated for a mammal at 1.52 × 10(–8) (95% credible interval: 1.28 × 10(−8)–1.78 × 10(−8)) mutations/site/generation. Further, we found an unexpectedly low count of paternal mutations, and only a modest overrepresentation of mutations at CpG sites. Despite the surprising nature of these results, we found both the rate and spectrum to be robust to the manipulation of a wide range of computational filtering criteria. We also sequenced a technical replicate to estimate a false-negative and false-positive rate for our data and show that any point estimate of a de novo mutation rate should be considered with a large degree of uncertainty. For validation, we conducted an independent analysis of context-dependent substitution types for gray mouse lemur and five additional primate species for which de novo mutation rates have also been estimated. These comparisons revealed general consistency of the mutation spectrum between the pedigree-based and the substitution-rate analyses for all species compared

Functionalized inorganic nanoparticles used as labels in solid-phase immunoassays

[EN] In recent years, research has focused on the development of different types of inorganic nanoparticles (NPs) to be used as labels in immunoassays instead of fluorophores or organic particles. Basically, inorganic NPs are characterized by their optimal optical properties (e.g., high photostability and high quantum yield). The inorganic NPs studied most have been silica NPs, quantum dots (QDs), noble metals, metal nanoshells and lanthanide oxides. This review presents a general overview on the progress of NP-preparation methods and NP-surface-functionalization procedures, in order to improve the sensitivity of the immunoassays involved. Other factors that must be taken into account are the type of solid-phase substrate (e.g., NP, microtiter plate, membrane and cover glass), format (i.e. direct or indirect) and the detection mode employed in the assay. Fluorescence has been used most as the detection mode. Also widely used has been time-resolved fluorescence with lanthanide ions as probes. Finally, our review of recent literature showed that most published immunoassays using inorganic NPs were applied to biological samples. (C) 2011 Elsevier Ltd. All rights reserved.Cháfer Pericás, MC.; Maquieira Catala, Á.; Puchades, R. (2012). Functionalized inorganic nanoparticles used as labels in solid-phase immunoassays. Trends in Analytical Chemistry. 31:144-156. doi:10.1016/j.trac.2011.07.011S1441563

Author response

The structure of axonal arbors controls how signals from individual neurons are routed within the mammalian brain. However, the arbors of very few long-range projection neurons have been reconstructed in their entirety, as axons with diameters as small as 100 nm arborize in target regions dispersed over many millimeters of tissue. We introduce a platform for high-resolution, three-dimensional fluorescence imaging of complete tissue volumes that enables the visualization and reconstruction of long-range axonal arbors. This platform relies on a high-speed two-photon microscope integrated with a tissue vibratome and a suite of computational tools for large-scale image data. We demonstrate the power of this approach by reconstructing the axonal arbors of multiple neurons in the motor cortex across a single mouse brain