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S. Pimpinelli - Heterochromatin, gene silencing and “RNA interference” in Drosophila of repetitive sequences and trasposons expression by playing a significant role in piRNAs-dependent RNAi silencing. The results of this work will be described in a manuscript in preparation. Selected publications Minervini CF, Marsano RM, Casieri P, Fanti L, Caizzi R, Pimpinelli S, Rocchi M, Viggiano L. Heterochromatin protein 1 interacts with 5'UTR of 66 transposable element ZAM in a sequence-specific fashion. Gene 2007, 393:1-10. Fanti L, Perrini B, Piacentini L, Berloco M, Marchetti E, Palumbo G, Pimpinelli S. The trithorax group and Pc group proteins are differentially involved in heterochromatin formation in Drosophila. Chromosoma 2008, 117:25-39. Fanti L, Pimpinelli S. HP1: a functionally multifaceted protein. Curr Opin Genet Dev. 2008, 18:169-74. Fig. 1 - (a) Localization of stellate sequences by FISH. As <strong>report</strong>ed also diagrammatically in (b) such sequences are arranged in two clusters on the X chromosome: one euchromatic and the other heterochromatic. One other cluster of Stellate-like sequences is located at the crystal locus of the Y chromosome. (c) Northern blot showing a mature coding stellate RNA that is present only in testes of X/0 males. (d) Two different rasiRNAs from the crystal sequences that are present only in testes of X/Y males. (e) Cristalline aggregates that present only in testes of X/0 males, and are decorated by an antibody against the stellate protein.
P a r t i c i p a n t s : Carla Boitani, professor; Elena Vicini, researcher; Barbara Muciaccia, Rossella Pugliesi, post-doc fellows; Margherita Grasso, Laura Grisanti, PhD students; Stefania Fera, Tiziana Menna, technicians. Report of activity The highly efficient process of sperm production is dependent on proper hormone balance, local cellular interactions and, more importantly, it relies on the biological activity of spermatogonial stem cells (SSCs), the stem cells of the germline. In the last years the activity of our group has focused on the isolation and characterization of SSCs. Our previous work has led us to the identification of SSCs in the testis “side population” (T-SP). Further characterization of T-SP SSCs by double vital staining with Hoechst and rhodamine, indicated that T-SP SSCs represent only a subset of SSCs. Of note, other groups were able to derive pluripotent stem cells from mouse and human germ cells in culture. Therefore, SSC subsets may be endowed with different functional properties and developmental potency. The aim of this project was to further characterize and exploit functional differences among SSC subsets. A complementary project carried out in our group was aimed to develop experimental strategies to achieve conditional gene inactivation in the germline. Identify spermatogonial stem cells heterogeneity in vivo Evidence for phenotypic and functional heterogeneity have been obtained after prospective isolation of SSC and their biological assay, namely germ cell transplantation. However there is no evidence for the presence of such stem subsets in vivo. In the accepted model, the SSCs are type Asingle spermatogonia (As). The As either self-renew by forming single Principal investigator: Mario Stefanini Professor of Histology and Embryology Dipartimento di Istologia ed Embriologia Medica Tel: (+39) 06 49766570; Fax:(+39) 06 4462854 mario.stefanini@uniroma1.it 67 Molecular genetics of eukaryotes - AREA 3 Biological characterization and in vitro culture of spermatogonial stem cells cells or generate pairs of cells, named type Apaired spermatogonia (Apr), connected by an intercellular bridge, which are committed to differentiate. To test the hypothesis that, in adult mouse testis, As spermatogonia are phenotypically heterogeneous, we have analyzed GFRA1 expression in undifferentiated spermatogonia. GFRA1 is the co-receptor for GDNF a niche-derived factor essential for SSC self-renewal and differentiation. As spermatogonia can be easily identified in whole mounted seminiferous tubules after immunostaining for the nuclear repressor PLZF. By immunofluorescence, confocal microscopy and morphometric analysis, we were able to demonstrate that 10% of the As cell population did not express this receptor. A common mechanism to generate cell diversity is the asymmetrical inheritance of proteins that specify daughter cell fate. We therefore analyzed by morphometric analysis the distribution of GFRA1 in daughter cells. We found doublet of daughter cells asymmetric for GFRA1 expression (5% of clones). This suggest that generation of SSC subsets may hold on asymmetric germ stem cell division. We next analyzed cell cycle kinetics of the two subsets by in vivo bromodeoxyuridine (BrdU) administration. Our results indicated that both subsets are actively engaged in cell cycle. A surrogate markers largely employed in different tissues for stem cells identification has been their preferential BrdU label retention, labeling-retaining-cells (LRCs). In fact, stem cells are expected to divide more slowly than many of their cell progeny. Time-course analysis after BrdU pulse labeling showed some LRCs at one month of chase. However, at two months no LRCs were identified. All together this indicate that germ stem cells are actively engaged in cell cycle and no quiescent stem cells are present in the adult testis, regardless of their GFRA1 expression pattern. Complementary observation in human testis samples also revealed that the most primitive germ cells are also heterogeneous for the expression of GFRA1. This observation lend further support to germ stem
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Istituto Pasteur Fondazione Cenci B
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Contents Forward by Paolo Amati, P
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Research area 6: New antimicrobial
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REPORT OF ACTIVITY 2007-2008 Boards
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REPORT OF ACTIVITY 2007-2008 Dario
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REPORT OF ACTIVITY 2007-2008 Meetin
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AREA1 Molecular biology of microorg
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P. Amati - Role of the early phases
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A. Boffi - Escherichia coli strains
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D. De Biase - The glutamate-based a
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A. Faggioni - Control of latency an
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Paola Londei - Translational regula
Page 27 and 28: A structural biology study of schis
Page 29 and 30: P a r t i c i p a n t s : Luigi Lem
Page 31 and 32: P a r t i c i p a n t s : Gianni Pr
Page 33 and 34: P a r t i c i p a n t s : Lucia Nen
Page 35 and 36: P a r t i c i p a n t s : Alessandr
Page 37 and 38: P a r t i c i p a n t s : Maurizio
Page 39: AREA3 Molecular genetics of eukaryo
Page 42 and 43: F. Ascenzioni - Development and ana
Page 44 and 45: P. Ballario - Molecular machines an
Page 46 and 47: I. Bozzoni - RNA-RNA and RNA-protei
Page 48 and 49: P. Caiafa - Crosstalk between poly(
Page 50 and 51: G. Camilloni - DNA topoisomerases a
Page 52 and 53: P. Costantino - The role of the DAG
Page 54 and 55: M. d’Erme - Epigenetic modificati
Page 56 and 57: P. Dimitri - Drosophila melanogaste
Page 58 and 59: L. Fabiani - DNA replication mechan
Page 60 and 61: C. Falcone - New tools in decipheri
Page 62 and 63: L. Frontali - New complex mitochond
Page 64 and 65: M. Gatti - The role of membrane tra
Page 66 and 67: A. Giacomello - Biology and physiol
Page 68 and 69: A. Gulino - Regulation of the Hedge
Page 70 and 71: M. Levrero - Histone Acetyltransfer
Page 72 and 73: F. Mangia - Molecular regulation of
Page 74 and 75: A. Musarò - Study of the molecular
Page 76 and 77: R. Negri - Role of the presumptive
Page 80 and 81: M. Stefanini - Biological character
Page 82 and 83: M. Tripodi - Molecular mechanisms o
Page 84 and 85: C. Turano - Roles of ERp57 in DNA r
Page 86 and 87: G. Zardo - Identification of novel
Page 89 and 90: P a r t i c i p a n t s : Carlo Tra
Page 91 and 92: P a r t i c i p a n t s : Giulia De
Page 93 and 94: P a r t i c i p a n t s : Giovanna
Page 95 and 96: P a r t i c i p a n t s : Francesco
Page 97 and 98: P a r t i c i p a n t s : Bruno Bot
Page 99 and 100: P a r t i c i p a n t s : Sergio Fu
Page 101 and 102: P a r t i c i p a n t s : Maria Egl
Page 103 and 104: P a r t i c i p a n t s : Stefano C
Page 105: AREA5 Cellular and molecular immuno
Page 108 and 109: V. Barnaba - Innovative strategies
Page 110 and 111: R. Foà - Potential role of miRNAS
Page 112 and 113: E. Piccolella - Analysis of the mol
Page 114 and 115: A. Santoni - Molecular mechanism un
Page 116 and 117: I. Screpanti - Analysis of the role
Page 118 and 119: R. Sorrentino - The role of HLA-B27
Page 120 and 121: L. Tuosto - CD28 co-stimulatory mol
Page 122 and 123: E. Ziparo - The role of Toll Like R
Page 125 and 126: Peptide effectors of innate immunit
Page 127 and 128: P a r t i c i p a n t s : Gustavo P
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P a r t i c i p a n t s : Roberta C
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P a r t i c i p a n t s : Giovanna
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P a r t i c i p a n t s : Livia Di
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P a r t i c i p a n t s : Marino Ar
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AREA7 Biology of malaria and other
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Della Torre - Petrarca - Bionomical
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A. Tramontano - Computational Analy
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Year 2007 Barile L, Chimenti I, Gae
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Puglisi R, Bevilacqua A, Carlomagno
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BIBLIOGRAPHY Conigliaro A, Colletti
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BIBLIOGRAPHY Muscolini M, Cianfrocc
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