The laminar position, morphology, and gene expression profiles of cortical astrocytes are influenced by time of birth from ventricular/subventricular progenitors.

Astrocytes that reside in superficial (SL) and deep cortical layers have distinct molecular profiles and morphologies, which may underlie specific functions. Here, we demonstrate that the production of SL and deep layer (DL) astrocyte populations from neural progenitor cells in the mouse is temporally regulated. Lineage tracking following in utero and postnatal electroporation with PiggyBac (PB) EGFP and birth dating with EdU and FlashTag, showed that apical progenitors produce astrocytes during late embryogenesis (E16.5) that are biased to the SL, while postnatally labeled (P0) astrocytes are biased to the DL. In contrast, astrocytes born during the predominantly neurogenic window (E14.5) showed a random distribution in the SL and DL. Of interest, E13.5 astrocytes birth dated at E13.5 with EdU showed a lower layer bias, while FT labeling of apical progenitors showed no bias. Finally, examination of the morphologies of "biased" E16.5- and P0-labeled astrocytes demonstrated that E16.5-labeled astrocytes exhibit different morphologies in different layers, while P0-labeled astrocytes do not. Differences based on time of birth are also observed in the molecular profiles of E16.5 versus P0-labeled astrocytes. Altogether, these results suggest that the morphological, molecular, and positional diversity of cortical astrocytes is related to their time of birth from ventricular/subventricular zone progenitors.

Relation between magnetic parameters and nematode abundance in agricultural soils of Portugal--a multidisciplinary study in the scope of environmental magnetism.

Soil is composed of different types of particles which are either natural or of anthropogenic origin. Anthropogenic particles are often related to the presence of heavy metals and thus provide information on soil quality. Magnetic parameters can detect the presence of such particles and may be used as a proxy for environmental pollution. This study explores the relationships between magnetic particles and the nematofauna of agricultural soils. Magnetic, pedological, microscopy and nematological analyses were conducted in soils collected from major regions of potato production in Portugal. The magnetic characterisation of soils identified regions with magnetic particles with possible anthropogenic origin. Microscopy analysis revealed the presence of spherical particles dominantly composed of Fe, O and C. A positive and significant relationship was found between saturation isothermal remanent magnetisation (SIRM) and mass-specific susceptibility (χ), confirming the importance the ferrimagnetic fraction to magnetic properties. The nematode communities were composed of nematodes belonging to four trophic groups (bacterial feeding, plant feeders, fungal feeders and omnivores/predators). The relationships between magnetic parameters and the nematodes showed that (1) S-25 has a linear correlation with number of nematodes per kilogram of soil and with plant feeders' trophic group and (2) SIRM correlates with the bacterial feeders trophic group. This study reveals that magnetic proxies may provide means for detecting regions with higher levels of pollution, possibly related to heavy metals. Due to the large background variability found in magnetic parameters, the sampling spacial mesh should to be further refined and the input of magnetic minerals needs to be locally calibrated.