The origins of developmental mechanisms and multipotent stem cells
Some of the most fascinating problems of biology concern spatial organization, temporal control, and stem cell behavior. The embryo developing from a single egg generates a pattern of differentiation and growth that is closely controlled and capable of remarkable regulation and recovery from injury. The ability of the embryo to diversify and of some adult tissues to regenerate throughout life is directly attributable to stem cells. Only stem cells have the capacity to self-renew and to differentitate along a specific lineage. Many pathological conditions are the failure to regulate growth, control differentiation, or establish the proper morphological connections.
The Bosch lab is concerned with the signal transduction chain leading to pattern formation and position dependent differentiation of uni- and pluripotent stem cells in the simple metazoan Hydra. We focus on three major problems of spatial and temporal control: (i) patterning along the single body axis formation in Hydra, (ii) control of position dependent gene activation, and (iii) the biology of multipotent stem cells in Hydra.
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Figure 2. Regeneration in Hydra. (A) Classical experiment demonstrating that a head or a foot can regenerate at the same axial location. (B) Regeneration of an intact polyp from a clump of isolated cells. Schematic drawing of pictures shown in Holstein et al. (2003). (C) In vivo tracking of EGFP expressing endodermal epithelial cells reveals that head regeneration occurs via morphallaxis in the absence of local cell proliferation. (D) Expression of peptide encoding gene Hym301 in the head region; in situ photograph courtesy of Dr. Konstantin Khalturin (Kiel). (E) Position dependent expression of anklet near the foot; in situ photograph courtesy of Dr. Yoshitaka Kobayakawa (Fukuoka). From: Bosch, 2007. Developmental Biology |
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Figure 3. Hydra epithelial cells have stem cell properties and are capable, by successive divisions, both of indefinite self-renewal and of producing different types of specialised cells such as tentacle or foot specific epithelial cells. The picture shows proliferation and differentiation of a pair of EGFP expressing endodermal epithelial cells in a nontransgenic host (A) leading successively (B-E) to a transgenic polyp expressing EGFP in all (F) of its endodermal epithelial cells. From: Bosch, 2007. Developmental Biology |