CSB329H1 Lecture Notes - Lecture 2: Endoderm, Cnidocyte, Subsequence
9 May 2018
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Lecture 2(c): Stem Cell Systems in Porifera and Cnidarins
1. Name three key components of a “stem cell niche”:
a. Support cells
b. Extracellular matrix
c. Basal lamina
2. In a double-pulse chase experiment, which is the first chase critical?
o Whether it is a single, or a multiple chase, the first chase is essential because we are
removing the analog from the first pulse
§ First ones has Cl-dU incorporated (i.e. green) and the second pulse had I-dU
(i.e. red); therefore staining them with their respective antibodies will allow us
to discriminate between the different replication sites
• However, if we did not complete the first chase, and wash out the
Cl-dU – it would be as if we place both Cl-dU and I-dU at the same
time; we cannot tell different replication sites
*first chase = “wash” | the most important thing after the first chase is the wash
Cnidarians – Hydra:
• If amputated, they are capable of regenerating their missing piece
o Biologically immortal: continuous self-renewal and differentiation
Hydra Anatomy:
• Similar to demosponge; they have no mesoderm
(diploblastic)
• Stem Cells:
o Interstitial stem cell
o Endoderm and ectodermal cells have
stem-like properties
(ends of the hydra are differentiated;
where stem cells are found – hermaphrodite)
Stem Cell Systems:
• There are three stem cell systems in Hydra:
o Epithelial cell linages represent unipotent stem cells; will recreate the
endoderm/ectoderm
§ Ectoderm cell only generates ectoderm; will not make endoderm (vise-versa)
o Interstitial stem cells exhibit multipotent features as they are able to differentiate
into nematocytes, nerve and gland cells
ð Epithelial cells are epithelimuscular cells; they have contractile activity – can swim
ð i-Cells = multipotent | Epithelial cells = unipotent
o Major cell types in cell linages are colored
o Derivative of interstitial cell linage in grey
§ Stem cell are not quiescent; continue to self-renew
Document Summary
Name three key components of a stem cell niche : Cl-du it would be as if we place both cl-du and i-du at the same time; we cannot tell different replication sites. *first chase = wash | the most important thing after the first chase is the wash. If amputated, they are capable of regenerating their missing piece: biologically immortal: continuous self-renewal and differentiation. Hydra anatomy: similar to demosponge; they have no mesoderm (diploblastic, stem cells, interstitial stem cell, endoderm and ectodermal cells have stem-like properties (ends of the hydra are differentiated; where stem cells are found hermaphrodite) Stem cell systems: there are three stem cell systems in hydra, epithelial cell linages represent unipotent stem cells; will recreate the endoderm/ectoderm. Ectoderm cell only generates ectoderm; will not make endoderm (vise-versa: interstitial stem cells exhibit multipotent features as they are able to differentiate into nematocytes, nerve and gland cells. Epithelial cells are epithelimuscular cells; they have contractile activity can swim.
