Lilach Gilboa
(PI)
Skirball Chair in New Scientists
Candiotty Building
Room 326
Weizmann Institute of Science,
Rehovot, 7610001, Israel
lilach.gilboa weizmann.ac.il
Tel: 972-8-934-3794
Research in our lab has made it clear that the decisions made by germ cells (whether to proliferate, become a stem cell or to differentiate) depend on somatic instructions. We have been able to determine which signals within somatic cells lead to interesting germ cell behavior. For example: EGFR signaling in the soma reduces germ cell proliferation. Somatic ecdysone signaling induces germ cell differentiation, and somatic Stat signaling induces germ cell cyst formation.
However, germ cells do not directly perceive any of these ‘usual’ signaling pathways. We still have no clue as to which signals the somatic cells send to germ cells to induce their specific behavior.
I am conducting a candidate approach screen of knocking-down cell-surface proteins that are highly expressed in germ cells to uncover how they sense their neighbors and how they receive their instructions.
The screen for germ-cell specific proteins that affect gonad development has yielded some truly exciting candidates. Importantly, none of these candidates belongs to the 'regular' developmental pathways. We therefore think we are uncovering the mysteries of how germ cells percieve somatic cell instructions.
Here are some of our contenders for the 'hottest' novel gene. Anti-Hts (magenta) stains somatic cell cortices and a reporter gene (green) marked differentiating germ cells. On the left a wild-type gonad (just to compare). At this stage of development, some germ cell differentiation can be observed even in wild-type.
Candidate 1 - knocking down this germ cell specific protein induces germ cell differentiation (more green). Importantly, the ovary is larger. This is the first clue we have that germ cells can affect gonadal size.
Candidate 2 - Germ cells fail to differentiate (no green labeling) and niches fail to form.
Candidate 3 - Somatic differentiation is completely normal, but germ cells fail to differntiate. This is a rare phenotype where germ cell and niche differentiation are uncoupled.
Which contender will be our favorite gene to study for the next few years? Stay tuned...
Our expert for :
Tissue culture / chromosome squashing / RT-PCR / Chromatin IP and every other method one might need.
Also:The lab advice center for balance in life.Every lab should have one.
Malka Popliker
(Lab Technician)
malka.popliker weizmann.ac.il
Tel: 972-8-934-2872
Here is an image of polytene chromosomes from slivary glands of 3rd instar larvae. The chromosomes are lableled with anti-EcR (red) and anti-Broad (green). Specific co-localization of these two chromatin-binding proteins can be observed at the Broad locus.
Ovarian stem cell units are formed during larval development. I’m interested in how the formation of these units is regulated by systemic cues, such as hormones and nutrition, and how these inputs funnel into major regulatory genes. I also want to find out how germ line stem cells (GSCs) differ from their precursors (PGCs). These differences may include features of asymmetric cell division, interaction with adult niches, chromatin states, and composition of transcription factors.
Dana Gancz
(Research Associate)
dana.gancz weizmann.ac.il
Tel: 972-8-934-2872
Wild-type ovaries at late third instar. Somatic cell cortices are in green, germ cells in blue and intermingling cells in magenta.
Depletion of ovarian Akt results in very small gonads. This and other nutritional studies we perform suggest that, ovarian development is coupled to the nutritional status of the organism.
Ovarian over-expression of the Insulin receptor results in larger gonads bearing twice as many niches. Germ cells differentiate precociously in these ovaries and form cysts.
Thus, the status of germ cell differentiation is coupled to somatic growth.
Escort cells send long protrusions towards the germline and are thought to engulf them. Escort cell nuclei (white) labelled by a Traffic jam antibody, extensions (magenta) via a Coracle antibody.
I recently joined Lilach’s lab as a postdoc to pursue my interest in germ line development. During my masters in the lab of Monika Hassel, I studied the specification and further development of primordial germ cells (PGCs) in the polychaete Platynereis dumerilii. I later joined the lab of Erez Raz for my Ph.D. thesis, where I investigated the role RNA-binding proteins and miRNAs in controlling the development of Zebrafish PGCs. I was particularly interested in how they acquire motile behavior.
The main question I tackle in Lilach’s lab is how the somatic cells of the gonad govern the maintenance of germ line stem cells (GSCs) and in what manner they promote their differentiation. I currently focus on the role of escort cells in promoting germ line stem cell differentiation. To this end, I combine genetics and a recently established live imaging set-up to monitor escort cell extensions. My goal is to elucidate how both cell types interact and influence the germ line.
In a related project, I investigate cell-autonomous aspects of primordial germ cell differentiation, utilizing in-silico analyses as well as genetic tools.
torsten.banisch weizmann.ac.il
Tel: 972-8-934-2872
Torsten Banisch
(Post-Doc)
doreen.ben-zvi weizmann.ac.il
Tel: 972-8-934-2872
Ever since the 17th century, life has been synonymous with cells: multiplying, producing proteins, and finally- decaying. But the marvels of the natural world from the humming bird to the blue whale, from green grass to giant sequoias, would not be here if cells could not combine and act in unison. To achieve this, cells embed themselves inside a mesh, named the Extra Cellular Matrix (ECM). The ECM provides anchorage for the cells, lends strength to the tissue, facilitates cell migration and mediates inter-cellular signaling. My interest lays in the role the ECM plays in the maintenance and differentiation of Germ Line Stem Cells (GSCs) of the fruit fly Drosophila Melanogaster. Very little is known about the composition of the ECM, which encapsulates the niche, stem cells, and their differentiated progeny, or about the influence it exerts on these cell types. In my work, I use confocal and electron microscopy as well as proteomic and genetic methods, to define ECM components and to shed light on their function in GSC maintenance and differentiation.
Doreen Ben-Zvi
(PhD Student)
SEM image showing the basal membrane of a Gemarium after removal of the Epithelial muscle sheath.
(A) In the control the niche is inhabited by Germ line stem cells (circled) recognizable by their round fusomes (arrowhead) and branched fusomes are further away from it (arrow). (B) RNAi directed against an ECM receptor results in cells with branched fusomes adjacent to the niche, indicating reduced stem cell maintenance (arrow).
(A, A') In control larval ovaries, Intermingled cells intercalate between germ cells and contain high levels of phosphorylated MAPK (green). (B-C') Removal of 'cottage' by two different RNAi lines results in loss of pMAPK staining and in a failure of intermingled cells to intercalate between germ cells.
I am investigating a novel gene (which we currently name cottage) and its effect on the somatic cells of the gonad. Interestingly, this gene is highly conserved between flies and mammals. However, its function has not been studied in any organism.
We have found that its transcript is up regulated in larval ovaries that express the constitutively active Epidermal Growth Factor Receptor (Egfr), and that removal of this gene from somatic cells of larval ovaries results in reduced MAPK phosphorylation.
In my work I characterize the knockdown phenotype of this gene in the Drosophila ovary and uncover possible functional relationship between this gene and the Egfr cascade.
I am also establishing an ex-vivo system in S2 cell culture that will enable us to study the biochemical aspects of the gene’s function.
racheli.begas weizmann.ac.il
Tel: 972-8-934-2872
Racheli Begas
(Masters Student)
Anna Weiner
(Student worker)
Why did Anna cross the road? To do nutrition projects of course!
We never know when we will see here but she will always have a smile :)
Tel: 972-8-934-2872
