Dentate gyrus NMDA receptors mediate rapid pattern separation in the hippocampal network

Forming distinct representations of multiple contexts, places, and episodes is a crucial function of the hippocampus. The dentate gyrus subregion has been suggested to fulfill this role. We have tested this hypothesis by generating and analyzing a mouse strain that lacks the gene encoding the essential subunit of the N-methyl-d-aspartate (NMDA) receptor NR1, specifically in dentate gyrus granule cells. The mutant mice performed normally in contextual fear conditioning, but were impaired in the ability to distinguish two similar contexts. A significant reduction in the context-specific modulation of firing rate was observed in the CA3 pyramidal cells when the mutant mice were transferred from one context to another. These results provide evidence that NMDA receptors in the granule cells of the dentate gyrus play a crucial role in the process of pattern separation.     

Switching skeletons: hydrostatic support in molting crabs

Skeletal support systems are essential for support, movement, muscular antagonism, and locomotion. Crustaceans shed their rigid exoskeleton at each molt yet are still capable of forceful movement. We hypothesize that the soft water-inflated body of newly molted crabs may rely on a hydrostatic skeleton, similar to that of worms and polyps. We measured internal hydrostatic pressure and the force exerted during claw adduction and observed a strong correlation between force and hydrostatic pressure, consistent with hydrostatic skeletal support. This alternation between the two basic skeletal types may be widespread among arthropods.     

Buying into the food system: Trends in food retailing in the US and implications for local foods

The contemporary US food systemis characterized by both an unprecedentedconcentration of corporate control as well as afragmentation of sourcing and marketingprocesses, introducing both new constraints andnew opportunities for more localized foodsystems. The purpose of our study is to explorethese issues by investigating three keyquestions. First, what are the key trends inthe US grocery industry? Second, how dodifferent kinds of food outlets choose,procure, and promote food products? Finally,what are the implications of recent trends inthe food retailing process for strengtheninglocal flows of the production, distribution,and consumption of food? Background informationon the grocery industry and the results ofseven open-ended interviews conducted withowners and managers of grocery stores in oneupstate New York county indicate that theretailing process differs in complex ways fromstore to store and in most aspects cannot beinferred from store type. The paper concludeswith a discussion of the implications of ourfindings for local food system efforts,specifically in terms of new collaborationsamong producers, distributors, retailers, andshoppers, who play an indispensable role indeveloping viable alternatives to increasingcorporate control.