Germline development in Platynereis dumerilii and its connection to embryonic patterning [Elektronische Ressource] / presented by Yanire Fabiola Zelada González

Informations

• Publié par: ruprecht-karls-universitat_heidelberg
• Publié le: 01 janvier 2005
• Nombre de lectures: 44
• Langue: English
• Poids de l'ouvrage: 155 Mo

Extrait

Dissertation
submitted to the
Combined Faculties for Natural Sciences and for Mathematics
of the Ruperto-Carola University of Heidelberg, Germany
for the degree of
Doctor of Natural Sciences
presented by
Diplom- Ing.: Yanire Fabiola Zelada González
born in: Guatemala, Guatemala
Oral examination: … . … . … … …Germline development in
Platynereis dumerilii and its connection to
embryonic patterning
Referees: Prof. Dr. Werner Müller
Prof. Dr. Gabriele PetersenTo my mother and my brother for their encouragement and exampleAcknowledgements
I am very thankful to the persons that made this study possible: Dr. Nicole Rebscher at
Heidelberg University for the supervision of my PhD thesis and correction of the text; Dr.
Detlev Arendt at EMBL in Heidelberg for giving me the opportunity to spend time in his
lab as a guest, for scientific advise and providing me with useful tools to write this work;
Prof. Dr. Werner Müller, Prof. Dr. Gabriele Petersen and the other members of my defense
committee for reviewing my thesis.
I want to acknowledge all members of Nicole Rebscher ’s team and Detlev Arendt’s lab, in
particular Dr. Nicole Rebscher for critical feedback on previous versions of this text; Dr.
Kristin Tessmar-Raible and Dr. Florian Raible for their corrections of the text, their useful
critical comments and interesting scientific discussions. I also want to thank persons that at
some time help me in practical issues, especially Tanja Kellner and Heidi Snyman.
I express my thanks for materials to Dr. Robert Savage and Dr. Mike Akam, who provided
me aliquots of the hunchback and vasa antibodies.
I want to thank the DFG (Deutsche Forschungsgemeinschaft) for the financial support
during the time of my thesis.
My special gratitude belongs to the persons that I was able to rely on during difficult times,
in particular Mario Zelada, Marc Wittmann and Biljana Jovanovics. I feel indebted to my
family who supported me in financial and emotional ways, especially to my parents and
my brother Jose Zelada.Table of Contents
Acknowledgements................................................................................................................................................... i
Table of Contents ....................................................................................................................................................ii
Index of Figures......................................................................................................................................................vi
Index of Tables.......................................................................................................................................................vii
1 INTRODUCTION ............................................................................................. 8
1.1 The evolution and phylogeny of Metazoa ............................................................................................. 9
1.2 Mechanisms for the establishment of the germ cells in Bilateria..................................................... 11
1.3 Connection between the specification germ cells and the establishment of embryonic axis........ 13
1.4 Platynereis dumerilii, an emerging model organism......................................................................... 15
1.4.1 Suitability of Platynereis as a model for cross-bilaterian comparisons ............................................ 15
1.4.2 Life cycle and embryonic development of Platynereis dumerilii...................................................... 17
1.5 Aim of this thesis .................................................................................................................................... 20
2 RESULTS...................................................................................................... 22
2.1 Germ cell specific genes......................................................................................................................... 23
2.1.1 Vasa is a germline marker and is expressed in not terminally differentiated cells........................... 24
2.1.2 Pl10 expression in Platynereis ............................................................................................................ 38
2.1.3 Pdu-vas and Pdu-pl10 expression in regenerating tails ..................................................................... 43
2.1.4 Piwi, an “active morphogenesis” marker that is co-expressed with vasa and pl10.......................... 46
2.1.5 Nanos is involved in PGCs’ formation............................................................................................... 48
2.2 Axis formation ........................................................................................................................................ 53
2.2.1 A/P patterning...................................................................................................................................... 53
2.2.1.1 Nanos - a putative hunchback repressor- is expressed in the nervous system in
Platynereis................................................................................................................................. 53
2.2.1.2 Hunchback expression in Platynereis suggests a role in proper segment formation ............. 54
2.2.1.3 Par-1 and pumilio homologs exist for the polychaete............................................................. 63
3 DISCUSSION ................................................................................................ 68Table of Contents iii
3.1 Importance of studying the development of the germline in the polychaete.................................. 69
3.1.1 Vasa, a suitable marker for tracing the germline in Platynereis........................................................ 70
3.1.1.1 Platynereis vasa codes for conserved domains characteristic of its protein family ............... 70
3.1.1.2 Primordial germ cells in Platynereis have a mesodermal origin............................................. 72
3.1.1.3 Restriction of vasa to the germ cell lineage ............................................................................. 73
3.1.1.4 Vasa expression in juveniles and mature worms ..................................................................... 74
3.1.2 Nanos is expressed in primordial germ cells...................................................................................... 77
3.1.3 A pumilio homolog exists in Platynereis ........................................................................................... 79
3.1.4 An additional feature of Par-1 is found in Platynereis....................................................................... 80
3.2 Relationship between the germ cells and undifferentiated cells (totipotent cells)......................... 82
3.2.1 Vasa expression in Platynereis suggests its ancestral role in not terminally differentiated tissue... 83
3.2.2 Comparison of Pdu-vas and Pdu-pl10 expression during the onset of gametogenesis .................... 85
3.2.3 Piwi expression in highly active proliferating cells........................................................................... 87
3.2.3.1 Conserved function of piwi in the germline............................................................................. 88
3.2.4 Implication of the expression of germline genes in the stomodaeum ............................................... 89
3.3 Conservation in the mechanism in establishing the A/P axis ........................................................... 90
3.3.1 Nanos, a putative translational repressor of hunchback in the polychaete ....................................... 91
3.4 Other conserved expression patterns of the analyzed genes............................................................. 94
3.4.1 Ancestral expression of nanos mRNA in the mesodermal lineage ................................................... 94
3.4.2 Nanos and pumilio expression in the brain and nervous system....................................................... 95
3.4.3 Pumilio expression in the nervous system ......................................................................................... 96
3.4.4 Hunchback expression is conserved among the lophotrochozoans................................................... 96
3.4.4.1 Hunchback is detected in the ventral plate of annelids............................................................ 96
3.4.4.2 Platynereis hunchback is expressed in the precursors of the prostomium and in transient
epithelia...................................................................................................................................... 97
3.4.4.3 Hunchback expression in the stomatoblasts............................................................................. 98
3.4.4.4 Up-regulation of hunchback mRNA in fully matured worms................................................. 99
4 MATERIALS AND METHODS .................................................................... 101
4.1 Technical equipment............................................................................................................................102
4.2 Worm culture........................................................................................................................................102
4.3 Standard cloning vectors and strains ................................................................................................103
4.4 Chemicals and Solutions..............................