Segregation of cortical head direction cell assemblies on alternating theta cycles

High-level cortical systems for spatial navigation, including entorhinal grid cells, critically depend on input from the head direction system. We examined spiking rhythms and modes of synchrony between neurons participating in head direction networks for evidence of internal processing, independent of direct sensory drive, which may be important for grid cell function. We found that head direction networks of rats were segregated into at least two populations of neurons firing on alternate theta cycles (theta cycle skipping) with fixed synchronous or anti-synchronous relationships. Pairs of anti-synchronous theta cycle skipping neurons exhibited larger differences in head direction tuning, with a minimum difference of 40 degrees of head direction. Septal inactivation preserved the head direction signal, but eliminated theta cycle skipping of head direction cells and grid cell spatial periodicity. We propose that internal mechanisms underlying cycle skipping in head direction networks may be critical for downstream spatial computation by grid cells.We kindly thank S. Gillet, J. Hinman, E. Newman and L. Ewell for their invaluable consultations and comments on previous versions of this manuscript, as well as M. Connerney, S. Eriksson, C. Libby and T. Ware for technical assistance and behavioral training. This work was supported by grants from the National Institute of Mental Health (R01 MH60013 and MH61492) and the Office of Naval Research Multidisciplinary University Research Initiative (N00014-10-1-0936). (R01 MH60013 - National Institute of Mental Health; MH61492 - National Institute of Mental Health; N00014-10-1-0936 - Office of Naval Research Multidisciplinary University Research Initiative)Accepted manuscrip

Relationship between Density and Biogenic Opal in Sediments from Sites 658 and 660

At Site 658, and especially at Site 660, sediments rich in biogenic opal were recovered. The fractions of biogenic silica, biogenic carbonate, and terrigenous material vary throughout the entire sequence at these sites (see chapters for Sites 658 and 660, this volume). At Site 660, biogenic-opal contents up to 100% are common in Eocene sediments. In studying these opal-rich sediments, a rapid method for estimating biogenic opal published by Mann and Muller (1980) was found useful. These authors applied an X-ray method which measures the height of a broad, diffuse reflection band of opal extending from about 15° to 32° 20, with a maximum at about 22° 20 (i.e., 4.04A) (Fig. 1, IB). Furthermore, this paper describes another method for estimating variations in the biogenic-opal content by using grain density. Grain density (p) can easily be determined by measuring the weight (G) and the volume (V) of the dry sediment, where p = G/P7g/cm3)

Nifedipine–pyrazine (2/1)

In the title compound, 2C17H18N2O6·C4H4N2 [systematic name: 3,5-dimethyl 2,6-dimethyl-4-(2-nitro­phen­yl)-1,4-di­hydro­pyridine-3,5-dicarboxyl­ate–pyrazine (2/1)], the complete pyrazine molecule is generated by crystallographic inversion symmetry. The center of the pyrazine ring lies on an inversion center. The nifedipine mol­ecules are linked into chains along the c axis through N—H⋯O hydrogen bonds, while the pyrazine mol­ecules are organized in the structure through van der Waals inter­actions

Regulation of Src and Csk nonreceptor tyrosine kinases in the filasterean Ministeria vibrans

ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.The development of the phosphotyrosine-based signaling system predated the evolution of multicellular animals. Single-celled choanoflagellates, the closest living relatives to metazoans, possess numerous tyrosine kinases, including Src family nonreceptor tyrosine kinases. Choanoflagellates also have Csk (C-terminal Src kinase), the enzyme that regulates Src in metazoans; however, choanoflagellate Csk kinases fail to repress the cognate Src. Here, we have cloned and characterized Src and Csk kinases from Ministeria vibrans, a filasterean (the sister group to metazoans and choanoflagellates). The two Src kinases (MvSrc1 and MvSrc2) are enzymatically active Src kinases, although they have low activity toward mammalian cellular proteins. Unexpectedly, MvSrc2 has significant Ser/Thr kinase activity. The Csk homologue (MvCsk) is enzymatically inactive and fails to repress MvSrc activity. We suggest that the low activity of MvCsk is due to sequences in the SH2-kinase interface, and we show that a point mutation in this region partially restores MvCsk activity. The inactivity of filasterean Csk kinases is consistent with a model in which the stringent regulation of Src family kinases arose more recently in evolution, after the split between choanoflagellates and multicellular animals. © 2014 American Chemical Society.Peer Reviewe

Spin-wave propagation in a microstructured magnonic crystal

Transmission of microwave spin waves through a microstructured magnonic crystal in the form of a permalloy waveguide of a periodically varying width was studied experimentally and theoretically. The spin wave characteristics were measured by spatially-resolved Brillouin light scattering microscopy. A rejection frequency band was clearly observed. The band gap frequency was controlled by the applied magnetic field. The measured spin-wave intensity as a function of frequency and propagation distance is in good agreement with a model calculation.Comment: 4 pages, 3 figure

Mesenchymal Stem Cells and Inflammatory Cardiomyopathy: Cardiac Homing and Beyond

Under conventional heart failure therapy, inflammatory cardiomyopathy usually has a progressive course, merging for alternative interventional strategies. There is accumulating support for the application of cellular transplantation as a strategy to improve myocardial function. Mesenchymal stem cells (MSCs) have the advantage over other stem cells that they possess immunomodulatory features, making them attractive candidates for the treatment of inflammatory cardiomyopathy. Studies in experimental models of inflammatory cardiomyopathy have consistently demonstrated the potential of MSCs to reduce cardiac injury and to improve cardiac function. This paper gives an overview about how inflammation triggers the functionality of MSCs and how it induces cardiac homing. Finally, the potential of intravenous application of MSCs by inflammatory cardiomyopathy is discussed