Microplastic burden in native (Cambarus appalachiensis) and non-native (Faxonius cristavarius) crayfish along semi-rural and urban streams in southwest Virginia, USA.

Our comparative assessment is the first study to investigate microplastic body burden in native (Cambarus appalachiensis) and non-native (Faxonius cristavarius) crayfish along a semi-rural and urban stream across different seasons. Crayfish, sediment, and surface water were collected, processed, and characterized using µRaman spectroscopy to compare microplastic polymer types and shapes across compartments. Average surface water concentrations were significantly higher in our urban stream compared to our semi-rural stream (17.3 ± 2.4 particles/L and 9.9 ± 1.3 particles/L, respectively; P = 0.015). Average sediment concentrations were similar between urban and semi-rural streams (140 ± 14.5 particles/kg and 139 ± 22.5 particles/kg, respectively; P = 0.957). Our findings showed a significant interactive effect of season, site, and nativity (i.e., species) regarding microplastic body burden in crayfish (P = 0.004). The smaller, non-native crayfish amassed more microplastic particles than the native crayfish (0.4-2.0 particles/g versus 0.4-0.8 particles/g, respectively). Fibers and fragments were the most common polymer shapes across compartments, with white and black being the dominant particle colors. Our study identified 13 plastic polymer types in crayfish and three in surface water and sediment; polypropylene was the most common polymer across compartments. This study provides evidence that crayfish body burden of microplastics can differ across species, seasons, and locations, highlighting the need for future studies to consider that sublethal impacts associated with microplastic body burden may vary by region and species.

Regulation of Atp7a RNA contributes to differentiation-dependent Cu redistribution in skeletal muscle cells.

Cu (Cu) is essential for several biochemical pathways due to its role as a catalytic cofactor or allosteric regulator of enzymes. Its import and distribution are tightly controlled by transporters and metallochaperones and Cu homeostasis is maintained by balancing Cu uptake and export. Genetic diseases are caused by impaired Cu transporters CTR1, ATP7A, or ATP7B but little is known about the regulatory mechanisms by which these proteins meet the fluctuating demands of Cu in specific tissues. Cu is required for differentiation of skeletal myoblasts to myotubes. Here, we demonstrate that ATP7A is needed for myotube formation and that its increased abundance during differentiation is mediated by stabilization of Atp7a mRNA via the 3' untranslated region. Increased ATP7A levels during differentiation resulted in increased Cu delivery to lysyl oxidase, a secreted cuproenzyme that needed for myotube formation. These studies identify a previously unknown role for Cu in regulating muscle differentiation and have broad implications for understanding Cu-dependent differentiation in other tissues.

Dopaminergic neurons are not a major Sonic hedgehog ligand source for striatal cholinergic or PV interneurons.

A model was previously proposed that DA neurons provide SHH ligand to striatal interneurons, which in turn support the survival of DA neurons through the release of trophic factors such as Glial cell-derived neurotrophic factor (GDNF). However, some key clinical observations do not support this proposed model, and a recent independent study shows that striatal cholinergic neuron survival does not rely on intact DA neuron projections. To resolve this discrepancy, we generated several independent mouse lines to examine the exact role of DA neuron-derived Shh signaling in the maintenance of the basal ganglia circuit and to identify the Shh-producing cells in the adult brain. Our data suggest that the deletion of Shh in DA neurons does not affect DA neuron survival or locomotive function in cKO mice during aging, nor does it affect the long-term survival of cholinergic or FS PV + interneurons in the striatum (STR).