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- Introduction
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1. Drosophila genetics - the first 25 years
- Prof. Dan Lindsley
- Establishment of the Primary Body Axes
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2. Homeotic genes in Drosophila's bithorax complex - The legacy of Ed Lewis
- Prof. Francois Karch
- Cell Type Specification and Organ Systems
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4. From germ cell specification to gonad formation
- Prof. Ruth Lehmann
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5. Drosophila stem cells
- Prof. Michael Buszczak
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6. Legacy of drosophila genetics: female germline stem cells
- Prof. Michael Buszczak
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7. Intestinal stem cell-mediated repair in Drosophila 1
- Prof. Tony Ip
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8. Intestinal stem cell-mediated repair in Drosophila 2
- Prof. Tony Ip
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10. Axon guidance in Drosophila
- Prof. John Thomas
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11. Development and physiology of the heart
- Prof. Rolf Bodmer
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12. Identification of host defenses in the Drosophila gut using genome-scale RNAi
- Prof. Dominique Ferrandon
- Genome Organization and Function
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13. The genetic analysis of meiosis in Drosophila melanogaster females
- Prof. R. Scott Hawley
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15. Dorsal-ventral patterning of the Drosophila embryo
- Prof. Mike Levine
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17. Genome-wide pooled CRISPR screen in arthropod cells
- Prof. Norbert Perrimon
- Behavior
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19. Genetics of chemosensory transduction: taste and smell
- Dr. Leslie Vosshall
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20. Cracking the case of circadian rhythms by Drosophila genetics
- Prof. Jeffrey C. Hall
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21. Sleep in Drosophila
- Dr. Ralph Greenspan
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23. Drosophila as a model for drug addiction
- Prof. Ulrike Heberlein
- Mechanism of Human Disease
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24. Cross-genomic analysis of human disease genes
- Prof. Ethan Bier
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25. Human neurodegenerative disease: insights from Drosophila genetics
- Prof. Nancy Bonini
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26. Metastasis of Drosophila tumors
- Prof. Allen Shearn
- Evolution of Adaptive Novelties
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28. The evolution of morphological novelty
- Prof. Nipam Patel
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29. The genetic architecture of complex traits: lessons from Drosophila
- Prof. Trudy Mackay
- Archived Lectures *These may not cover the latest advances in the field
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30. Using gene expression information to provide insights into patterning and differentiation
- Prof. Angelike Stathopoulos
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31. Regulation of gastrulation in Drosophila
- Prof. Dr. Maria Leptin
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32. microRNA function in stem cells
- Prof. Hannele Ruohola-Baker
Printable Handouts
Navigable Slide Index
- Introduction
- Germ cells are forever
- Life cycle of the germ line
- Why are germ cells special?
- Primordial germ cells formation
- Germ plasm specifies germ cells
- Germ cells formation in the early embryo
- What is germ plasm?
- Cytoplasmic polarity and germ plasm assembly
- RNA localization
- RNA localization mechanism
- How does Nanos RNA localize?
- Oskar protein and germ plasm organization
- Oskar controls germ-plasm and -cells quantity
- RNA localized in cells by 3' untranslated regions
- Oskar protein induces ectopic germ cell formation
- Oskar RNA transport, localization and translation
- A germ plasm pathway
- Epigenetic control of early germ cell development
- Transcription is repressed in early germ cells
- PGC gene represses transcription in PGC's
- pgc required for germ cells migration and survival
- Germ cells formation in different species
- Germ cell migration
- Migration in a changing environment
- Germ cell migration in Drosophila
- Germ cell migratory behavior
- Identification of genes required for GC migration
- Mis/overexpression screens
- Migration step I: migration through posterior midgut
- Migration through the posterior midgut epithelium
- Orphan GPCR expressed and required in GC's
- Migration step II: movement on posterior midgut
- wunen and wunen 2 expression in soma
- wunen and wunen 2 expression on midgut
- wun and wun2 homologous to mammalian LPPs
- What are the Wunens and LPPs?
- Model for Wunen function in soma
- Wunen2 is needed in germ cells for survival
- Germ line and somatic Wunens - opposing roles
- Competitive relationship of soma and germ line
- Lipids regulate the migration of several cell types
- Migration step III: movement into mesoderm
- Attraction to gonadal mesoderm
- Somatic Wunens shepherd GCs by repulsion
- Wunen sorts PGCs along midline
- Different midline repellants for germ cells
- Wunen/LPP3 - major determinant of GC migration
- Migration step IV: attraction to gonadal mesoderm
- Gonadal mesoderm specification
- Columbus/hmgcr expressing cells attract GCs
- The isoprenoid biosynthetic pathway
- Isoprenylation is the critical step in the pathway
- Three independent signaling pathways
- Mouse germ cell migration
- Germ cell migration in the zebrafish
- CXCR4 guides the germ cells
- The life cycle of germ cells
- Growth of the gonad
- Gonad growth and GC number during larval stages
- PGC proliferation is a regulated process
- Too few PGCs results in empty GSC niches
- A mis/over-expression screen in the larval ovary
- Loss of EGF receptor (DER) signaling
- EGFR signaling is detected in intermingled cells
- Increased EGFR signaling blocks proliferation
- Spitz ligand in germ cell activates EGFR
- Intermingled cells die without EGFR signaling
- Two roles for EGFR signaling in GC homeostasis
- From primordial germ cell to germ line stem cell
- Germ line stem cell division
- Signaling for stem cell maintenance
- Stem cell maintenance and differentiation
- Dpp represses bam transcription in GSCs
- PGCs differentiate at the end of larval development
- Stem cell signals act on PGCs
- Niche restriction controls initial stem cell selection
- Are PGC's actually germ line stem cells?
- Conclusions - conserved aspects of germ cells
- Acknowledgements
Topics Covered
- Germ cells: the ultimate stem cell
- Germ plasm specifies germ cells
- The genetics of early Drosophila development: maternal effect mutations
- The body pattern of the embryo is preformed during oogenesis by localization of RNA
- In Drosophila, the Oskar protein is necessary and sufficient to organize germ plasm
- Oskar RNA transport, localization and translation are regulated at many levels
- Epigenetic control of early germ cell development
- Transcription
- Germ cell migration
- Wunen
- Signaling pathways
- The life cycle of germ cells
- Growth of the gonad
- Genetic analysis of stem cell maintenance and differentiation
- Conserved aspects of germ cells
Links
Series:
Categories:
Therapeutic Areas:
Talk Citation
Lehmann, R. (2018, May 31). From germ cell specification to gonad formation [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved November 5, 2024, from https://doi.org/10.69645/BURV1022.Export Citation (RIS)
Publication History
Financial Disclosures
- Prof. Ruth Lehmann has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.
A selection of talks on Gynaecology & Obstetrics
Transcript
Please wait while the transcript is being prepared...
0:00
My name is Ruth Lehmann, and I work at
the Howard Hughes Medical Institute and
at the Helen and Martin Kimmel Center for
Biology at the Skirball Institute
at NYU Medical School.
I would like to talk today
about germ cell specification,
going all the way from how
germ cells initially form,
to how eventually a gonad forms, and how
germ cells become germ line stem cells.
0:25
What this is really about is
that germ cells are forever.
While, when a fertilized egg cell starts
to begin its development into its zygote,
the soma will eventually die earlier or
later.
However, a primordial germ cell that
will be set aside really early during
the development of the embryo
will go on forever.
Because if it is allowed to give
rise to a germ line stem cell and
then produce either egg or sperm,
it can give rise to another organism.
And so,
when we think about germ line development,
we really have to think about
a life cycle of the germ line.
And also, to some extent, an eternal
cycle, because this gives not only
rise to a new organism, but it also,
the germ cell, maintains the species.
1:11
So I would like to introduce the lifecycle
of the germ line, and in particular,
germ cells that we work on, and
that is the Drosophila germ cells.
So we have here the life
cycle in the center,
where a fly female meets the fly male.
And their product is then fertilized egg,
which will develop into an embryo.
And very early on,
the primordial germ cells will form and
be set aside in this embryo.
These germ cells will then
migrate to the embryonic gonad,
which is the somatic part of the gonad.
And here, sexual identity will
be bestowed on the germ cells.
And during three larval stages,
this embryonic gonad will grow
into a larval and pupal gonad.
And during that time, primordial germ
cells will keep on dividing, and
there will be many,
many more of these primordial germ cells.
Until eventually, in the female,
the germ cells are set aside,
some of them becoming
germ line stem cells.
And so, in my presentation today,
I will focus a lot on how primordial
germ cells are initially set aside.
I will then focus on the process
of germ cell migration.
And then briefly, I will talk about
a few aspects of what happens actually
when these primordial germ cells
have to become germ line stem cells.
And then there are other lectures in these
series which talk about what actually
happens during oogenesis, and so
I'm leaving this out of my life cycle for
germ cells.