Biological membranes contain an extraordinary diversity of lipids. Phospholipids function as major structural elements of cellular membranes, and analysis of changes in the highly heterogeneous mixtures of lipids found in eukaryotic cells is central to understanding the complex functions in which lipids participate. Phospholipase-catalyzed hydrolysis of phospholipids often follows cell surface receptor activation. Recently, we demonstrated that granule fusion is initiated by addition of exogenous, nonmammalian phospholipases to permeabilized mast cells. To pursue this finding, we use positive and negative mode Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) to measure changes in the glycerophospholipid composition of total lipid extracts of intact and permeabilized RBL-2H3 (mucosal mast cell line) cells. The low energy of the electrospray ionization results in efficient production of molecular ions of phospholipids uncomplicated by further fragmentation, and changes were observed that eluded conventional detection methods. From these analyses we have spectrally resolved more than 130 glycerophospholipids and determined changes initiated by introduction of exogenous phospholipase C, phospholipase D, or phospholipase A 2. These exogenous phospholipases have a preference for phosphatidylcholine with long polyunsaturated alkyl chains as substrates and, when added to permeabilized mast cells, produce multiple species of mono-and polyunsaturated diacylglycerols, phosphatidic acids, and lysophosphatidylcholines, respectively. The patterns of changes of these lipids provide an extraordinarily rich source of data for evaluating the effects of specific lipid species generated during cellular processes, such as exocytosis. mast cells ͉ phospholipases ͉ exocytosis P hospholipids play important roles in transmembrane signaling processes as well as in dynamic aspects of cell membrane structure. The major phospholipids found in the membranes of mammalian cells include phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and phosphatidylglycerol (PG). Some exist as both sphingolipids and glycerophospholipids, as plasmalogens and glycerol diesters, as polyphosphorylated species (e.g., PIs), and with a diverse and specialized array of alkyl chains. Phospholipid metabolism is regulated by distinct types of extracellular receptor-regulated pathways in a variety of ways, including generation of first and second messengers [inositol trisphosphate, phosphatidylinositol 4,5-bisphosphate, platelet-activating factor, diacylglycerol (DAG), sphingosine, etc.]; modifications associated with membrane fusion, secretion, trafficking, and plasma membrane shape change; and to date vaguely described changes in bilayer structure needed to regulate the activities of enzymes, channels, and transport proteins. The chemical and physical properties of membranes are largely dependent on the phospholipid composition (1-4). Although the biological significance of lipid heteroge...

Disrupted-in-Schizophrenia 1 (DISC1) is a promising genetic risk factor for major mental disorders. Many groups repeatedly reported a role for DISC1 in brain development in various strains of mice and rats by using RNA interference (RNAi) approach. Nonetheless, due to the complexity of its molecular disposition, such as many splice variants and a spontaneous deletion in a coding exon of the DISC1 gene in some mouse strains, there have been debates on the interpretation on these published data. Thus, in this study, we address this question by DISC1 knockdown via short-hairpin RNAs (shRNAs) against several distinct target sequences with more than one delivery methodologies into several mouse strains, including C57BL/6, ICR, and 129X1/SvJ. Here, we show that DISC1 knockdown by in utero electroporation of shRNA against exons 2, 6, and 10 consistently results in neuronal migration defects in the developing cerebral cortex, which are successfully rescued by coexpression of full-length DISC1. Furthermore, lentivirus-mediated shRNA also led to migration defects, which is consistent with two other methodologies already published, such as plasmidmediated and retrovirus-mediated ones. The previous study by Song's group also reported that, in the adult hippocampus, the phenotype elicited by DISC1 knockdown with shRNA targeting exon 2 was consistently seen in both C57BL/6 and 129S6 mice. Taken together, we propose that some of DISC1 isoforms that are feasible to be knocked down by shRNAs to exon 2, 6, and 10 of the DISC1 gene play a key role for neuronal migration commonly in various mouse strains and rats.

Roles for glycerophospholipids in exocytosis have been proposed, but remain controversial. Phospholipases are stimulated following the activation of the high-affinity receptor for immunoglobulin E (IgE) in mast cells. To study the biochemical sequelae that lead to degranulation, broken cell systems were employed. We demonstrate that the addition of three distinct types of exogenous phospholipases (i.e., bcPLC, scPLD, and tfPLA(2)), all of which hydrolyze phosphatidylcholine (PC), trigger degranulation in permeabilized RBL-2H3 cells, a mucosal mast cell line. Production of bioactive lipids by these phospholipases promotes release of granule contents through the plasma membrane and acts downstream of PKC, PIP(2), and Rho subfamily GTPases in regulated secretion. These exogenous phospholipase-induced degranulation pathways circumvent specific factors activated following stimulation of the IgE receptor as well as in ATP- and GTP-dependent intracellular pathways. Taken together, these results suggest that regulated secretion may be achieved in vitro in the absence of cytosolic factors via phospholipase activation and that products of PC hydrolysis can promote exocytosis in mast cells.

This qualitative study explored the cultural identity negotiation of young adult immigrants. Using a grounded theory research design, 10 semistructured interviews were conducted with emerging adult immigrants (EAI), ages 19-27. Results yielded a substantive model of cultural identity negotiation (MCIN) for EAI and posited that is at the core of how participants navigate their cultural identities. This model included 6 major categories: (a); (b) ; (c); (d) ; (e) Desire; (f) , as well as 2 overarching factors (), which were found to be influential on participants' cultural identity negotiation. The model also included the identification of 4 approaches to cultural identity negotiation: (a) Blended; (b) Dual; (c) Disconnected; and (d) Intermediate. The MCIN for EAI is discussed in terms of the current literature on cultural identity formation as well as implications for counseling psychology training and practice. Recommendations for further research are also suggested. (PsycINFO Database Record