Malhotra's Lab

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0><script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-47423994-1', 'fortunecity.ws'); ga('send', 'pageview'); </script> <center> <br> <div> <script language="javascript" type="text/javascript" src="http://ad.broadcaststation.net/ads/show_ad.php?width=728&height=90"></script> </div> </center> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=175 BGCOLOR="#669999" TEXT="#080000"> <div> <B> <TABLE BORDER="0" CELLPADDING="2" CELLSPACING="1" WIDTH="773" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="LEFT" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 166 ><NOBR><div> <B> <img src="HTMLobj-263/aniGif.gif" border="0" align="bottom" width="400" height="161">  </B></div> </NOBR></tD> <tD VALIGN=CENTER><NOBR><div> <B>Malhotra's Lab</B></div> <div> <B>(on pursuit of Golgi's mysteries)</B></div> <bR> </NOBR></tD> </tR> </TABLE></B></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#33FFFF" TEXT="#080000"> <div> <A HREF="id34.htm" TARGET="_top" TITLE="Lab Members"><U><B><IMG SRC="0b5bd200.gif" border=0 width="189" height="32" ALT="Adobe Photoshop Image" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Publications"><U><B><IMG SRC="0b8bd200.gif" border=0 width="189" height="32" ALT="Adobe Photoshop Image" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> <div> <A HREF="id19.htm" TARGET="_top" TITLE="Related Links"><U><B><IMG SRC="0b9bd200.gif" border=0 width="189" height="32" ALT="Adobe Photoshop Image" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> <div> <A HREF="id33.htm" TARGET="_top" TITLE="Lab Pictures"><U><B><IMG SRC="0babd200.gif" border=0 width="189" height="32" ALT="Adobe Photoshop Image" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> <div>  <img src="HTMLobj-264/aniGif.gif" border="0" align="bottom" width="120" height="82">  </div> </td> <td valign="top" height=305 BGCOLOR="#66FFCC" TEXT="#080000"> <div> <B>MEMBRANE FUSION AND ORGANELLAR ARCHITECTURE </B></div> <bR> <div> Membrane fusion, be it between transport vesicles and the target membrane or during organelle biogenesis, is a fascinating process of fundamental importance. This exceedingly complex and tightly regulated process guides events as diverse as synaptic transmission, hormone release, cellularization and development. While some components of the fusion machinery have recently been identified, many key components remain unknown. We are interested in membrane fusion mainly from the point of organelle assembly and establishment of cellular boundaries. For this we are exploiting two different systems: The process by which stacks of Golgi cisternae are built in the cytoplasm of mammalian cells and the cellularization of <I>Drosophila</I> embryos. </div> <bR> <div> <B>VESICULATION AND ASSEMBLY OF GOLGI STACKS </B><I><B>IN VITRO </B></I></div> <bR> <div> We have taken a unique approach to first dismantle Golgi stacks into small vesicles (VGMs for vesiculated Golgi membranes) of 60-90 nm diameter by treatment of cells with a novel compound ilimaquinone (IQ). Stack formation from VGMs is then reconstituted in permeabilized cell preparations. This assay has allowed us to identity novel proteins involved in membrane fusion and in shaping these membranes into a very unique structure, i.e., stacks of cisternae. Additionally, we have reconstituted the process of Golgi vesiculation by IQ, and our results indicate that this process involves a novel mechanism which is regulated by heterotrimeric G-proteins. These assays are being used to functionally dissect the processes by which Golgi stacks are built in the cytoplasm of mammalian cells. </div> <bR> <div> <B>CELLULARIZATION OF DROSOPHILA EMBRYOS</B> </div> <bR> <div> <I>Drosophila</I> embryos undergo a synchronized cellularization process by which a syncitial embryo is converted into a multicellular blastoderm. The origin of this extra membrane, the process by which the membranes are pulled into the embryonic cytoplasm and then fuse to form approximately 6000 cells, is largely unknown. We have shown that Golgi membranes are restricted to the cortex of the developing embryo, and their organization with respect to the rapidly dividing nuclei is thus different from that observed in mammalian cells. We have generated a number of drosophila-Golgi specific monoclonal antibodies. These antibodies recognize novel proteins, as the peptide sequences show no significant homologies to known proteins. Our aim is to use these antibodies in combination with other reagents to address the following questions: how How membranes are retained in the cortex of the developing embryo; what is the source of membrane required for the cellularization process; how membranes fuse during the cellularization process, with special attention to the components of fusion machinery and the regulation of the timing of membrane fusion to ensure that essential cellular organelles are encapsulated into the newly forming cells. </div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> You are the visitor #:</div> <div>   <a href="http://counter.mycomputer.com/"><img alt="Counter" src="http://counter.mycomputer.com/c.count?u=diazanel&c=1" border=0></a>   </div> <bR> <div> <B> <img src="HTMLobj-266/aniGif.gif" border="0" align="bottom" width="184" height="77">  </B></div> <div> <B>(This counter doesn't work, even </B></div> <div> <B>with a monkey working on it)</B></div> <bR> <div> <B>This site was created by Alberto Díaz Añel</B></div> <div> <A HREF="mailto:diazanel@biomail.ucsd.edu" TARGET="_top" TITLE="mailto:diazanel@biomail.ucsd.edu"><U><B> <img src="HTMLobj-165/aniGif.gif" border="0" align="bottom" width="64" height="48">  </B></U></A></div> <div> <B>Last actualization: 02/12/2001</B></div> </td> </tr></table></body>