Proteomic analysis during larval development and metamorphosis of the spionid polychaete Pseudopolydora vexillosa

<p>Abstract</p> <p>Background</p> <p>While the larval-juvenile transition (metamorphosis) in the spionid polychaete <it>Pseudopolydora vexillosa </it>involves gradual morphological changes and does not require substantial development of juvenile organs, the opposite occurs in the barnacle <it>Balanus amphitrite</it>. We hypothesized that the proteome changes during metamorphosis in the spionids are less drastic than that in the barnacles. To test this, proteomes of pre-competent larvae, competent larvae (ready to metamorphose), and juveniles of <it>P. vexillosa </it>were compared using 2-dimensional gel electrophoresis (2-DE), and they were then compared to those of the barnacle.</p> <p>Results</p> <p>Unlike the significant changes found during barnacle metamorphosis, proteomes of competent <it>P. vexillosa </it>larvae were more similar to those of their juveniles. Pre-competent larvae had significantly fewer protein spots (384 spots), while both competent larvae and juveniles expressed about 660 protein spots each. Proteins up-regulated during competence identified by MALDI-TOF/TOF analysis included a molecular chaperon (calreticulin), a signal transduction regulator (tyrosin activation protein), and a tissue-remodeling enzyme (metallopeptidase).</p> <p>Conclusions</p> <p>This was the first time to study the protein expression patterns during the metamorphosis of a marine polychaete and to compare the proteomes of marine invertebrates that have different levels of morphological changes during metamorphosis. The findings provide promising initial steps towards the development of a proteome database for marine invertebrate metamorphosis, thus deciphering the possible mechanisms underlying larval metamorphosis in non-model marine organisms.</p

Stem cell transplantation therapies in Parkinson’s disease

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Phosphoproteome analysis during larval development and metamorphosis in the spionid polychaete Pseudopolydora vexillosa

<p>Abstract</p> <p>Background</p> <p>The metamorphosis of the spionid polychaete <it>Pseudopolydora vexillosa </it>includes spontaneous settlement onto soft-bottom habitats and morphogenesis that can be completed in a very short time. A previous study on the total changes to the proteome during the various developmental stages of <it>P. vexillosa </it>suggested that little or no <it>de novo </it>protein synthesis occurs during metamorphosis. In this study, we used multicolor fluorescence detection of proteins in 2-D gels for differential analysis of proteins and phosphoproteins to reveal the dynamics of post-translational modification proteins in this species. A combination of affinity chromatography, 2D-PAGE, and mass spectrometry was used to identify the phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles.</p> <p>Results</p> <p>We reproducibly detected 210, 492, and 172 phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles, respectively. The highest percentage of phosphorylation was observed during the competent larval stage. About 64 stage-specific phosphoprotein spots were detected in the competent stage, and 32 phosphoproteins were found to be significantly differentially expressed in the three stages. We identified 38 phosphoproteins, 10 of which were differentially expressed during metamorphosis. These phosphoproteins belonged to six categories of biological processes: (1) development, (2) cell differentiation and integrity, (3) transcription and translation, (4) metabolism, (5) protein-protein interaction and proteolysis, and (6) receptors and enzymes.</p> <p>Conclusion</p> <p>This is the first study to report changes in phosphoprotein expression patterns during the metamorphosis of the marine polychaete <it>P. vexillosa</it>. The higher degree of phosphorylation during the process of attaining competence to settle and metamorphose may be due to fast morphological transitions regulated by various mechanisms. Our data are consistent with previous studies showing a high percentage of phosphorylation during competency in the barnacle <it>Balanus amphitrite </it>and the bryozoan <it>Bugula neritina</it>. The identified phosphoproteins may play an important role during metamorphosis, and further studies on the location and functions of important proteins during metamorphosis are warranted.</p

Application of the transferrin receptor-mediated drug delivery systems in the treatment of acute cerebral infarction

2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

The expression of hephaestine during focal cerebral ischemia in rats

2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Brain iron metabolism and neurodegenerative diseases

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from $^{83m}$Kr internal conversion electrons is comparable to that from $^{207}$Bi conversion electrons, we obtained the numbers of excitons ($N_{ex}$) and ion pairs ($N_i$) and their ratio ($N_{ex}/N_i$) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.Comment: v2 to reflect published versio

A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator

When electrons are subject to a large external magnetic field, the conventional charge quantum Hall effect \cite{Klitzing,Tsui} dictates that an electronic excitation gap is generated in the sample bulk, but metallic conduction is permitted at the boundary. Recent theoretical models suggest that certain bulk insulators with large spin-orbit interactions may also naturally support conducting topological boundary states in the extreme quantum limit, which opens up the possibility for studying unusual quantum Hall-like phenomena in zero external magnetic field. Bulk Bi$_{1-x}$Sb$_x$ single crystals are expected to be prime candidates for one such unusual Hall phase of matter known as the topological insulator. The hallmark of a topological insulator is the existence of metallic surface states that are higher dimensional analogues of the edge states that characterize a spin Hall insulator. In addition to its interesting boundary states, the bulk of Bi$_{1-x}$Sb$_x$ is predicted to exhibit three-dimensional Dirac particles, another topic of heightened current interest. Here, using incident-photon-energy-modulated (IPEM-ARPES), we report the first direct observation of massive Dirac particles in the bulk of Bi$_{0.9}$Sb$_{0.1}$, locate the Kramers' points at the sample's boundary and provide a comprehensive mapping of the topological Dirac insulator's gapless surface modes. These findings taken together suggest that the observed surface state on the boundary of the bulk insulator is a realization of the much sought exotic "topological metal". They also suggest that this material has potential application in developing next-generation quantum computing devices.Comment: 16 pages, 3 Figures. Submitted to NATURE on 25th November(2007