Regulation of NMDA receptors by the tyrosine kinase Fyn

The phosphorylation and trafficking of N-methyl-d-aspartate (NMDA) receptors are tightly regulated by the Src family tyrosine kinase Fyn, through dynamic interactions with various scaffolding proteins in the NMDA receptor complex. Fyn acts as a point of convergence for many signaling pathways that upregulate GluN2B-containing NMDA receptors. In the following review, we focus on Fyn signaling downstream of different G-protein-coupled receptors: the dopamine D1 receptor, and receptors cognate to the pituitary adenylate cyclase-activating polypeptide. The net result of activation of each of these signaling pathways is upregulation of GluN2B-containing NMDA receptors. The NMDA receptor is a major target of ethanol in the brain, and accumulating evidence suggests that Fyn mediates the effects of ethanol by regulating the phosphorylation of GluN2B NMDA receptor subunits. Furthermore, Fyn has been shown to regulate alcohol withdrawal and acute tolerance to ethanol through a GluN2B-dependent mechanism. In addition to its effects on NMDA receptor function, Fyn also modifies the threshold for synaptic plasticity at CA1 synapses, an effect that probably contributes to the effects of Fyn on spatial and contextual fear learning.     

Hurricane Risk Variability along the Gulf of Mexico Coastline

Hurricane risk characteristics are examined across the U. S. Gulf of Mexico coastline using a hexagonal tessellation. Using an extreme value model, parameters are collected representing the rate or λ (frequency), the scale or σ (range), and the shape or ξ (intensity) of the extreme wind distribution. These latent parameters and the 30-year return level are visualized across the grid. The greatest 30-year return levels are located toward the center of the Gulf of Mexico, and for inland locations, along the borders of Louisiana, Mississippi, and Alabama. Using a geographically weighted regression model, the relationship of these parameters to sea surface temperature (SST) is found to assess sensitivity to change. It is shown that as SSTs increase near the coast, the frequency of hurricanes in these grids decrease significantly. This reinforces the importance of SST in areas of likely tropical cyclogenesis in determining the number of hurricanes near the coast, along with SSTs along the lifespan of the storm, rather than simply local SST. The range of hurricane wind speeds experienced near Florida is shown to increase with increasing SSTs (insignificant), suggesting that increased temperatures may allow hurricanes to maintain their strength as they pass over the Florida peninsula. The modifiable areal unit problem is assessed using multiple grid sizes. Moran’s I and the local statistic G are calculated to examine spatial autocorrelation in the parameters. This research opens up future questions regarding rapid intensification and decay close to the coast and the relationship to changing SSTs.     

Dominant drivers of plant community assembly vary by soil type and time in reclaimed forests

Information on plant community assembly mechanisms is limited on forest reclamation sites after mining in the Canadian boreal forest. We assessed the change in plant community composition after Year 2 and Year 5 on species-rich forest floor mineral mix (FFMM) and species-poor peat mineral mix (PMM) reclamation soils by examining assembly mechanisms, i.e., seed bank, seed rain, biotic dispersal, vegetative expansion, and competition. Initial plant cover and diversity were greater on FFMM due to non-native species originating from the seed bank, which had 5× more seeds in the FFMM. By Year 5, both soil types had approximately 40% cover and 80 species richness due to the addition of wind and biotic-dispersed species and were characterized by a shift towards native species. Native forbs using vegetative reproduction expanded up to 2 m from FFMM into PMM. At Year 5 competition does not seem to have a large role in the structuring of the vegetation community. Overall, multiple factors were involved in structuring plant communities on reclamation sites, but we observed a general convergence between plant communities on different soil types in a relatively short period of time.

     

Whole body synthesis rates of DHA from α-linolenic acid are greater than brain DHA accretion and uptake rates in adult rats

Docosahexaenoic acid (DHA) is important for brain function, however, the exactamount required for the brain is not agreed upon. While it is believed that thesynthesis rate of DHA from α-linolenic acid (ALA) is low, how thissynthesis rate compares with the amount of DHA required to maintain brain DHAlevels is unknown. The objective of this work was to assess whether DHAsynthesis from ALA is sufficient for the brain. To test this, rats consumed adiet low in n-3 PUFAs, or a diet containing ALA or DHA for 15 weeks. Over the 15weeks, whole body and brain DHA accretion was measured, while at the end of thestudy, whole body DHA synthesis rates, brain gene expression, and DHA uptakerates were measured. Despite large differences in body DHA accretion, there wasno difference in brain DHA accretion between rats fed ALA and DHA. In rats fedALA, DHA synthesis and accretion was 100-fold higher than brain DHA accretion ofrats fed DHA. Also, ALA-fed rats synthesized approximately 3-fold more DHA thanthe DHA uptake rate into the brain. This work indicates that DHA synthesis fromALA may be sufficient to supply the brain.