Advanced Developmental Biology Flashcards
Define stem cells!
Cells with unrestricted potential and capability for endless renewal giving rise to daughter cells identical to the mother cells. Both daughter cells are equally potent in adopting a multitude of fates.
(Problematic statements)
What is the function of embryonic stem cells? What about adult ones?
Embryonic stem cells supply the massive expansion and differentiation of the embryo. At the earliest stage, a single cell is capable of enough renewal to supply a whole organism.
Adult stem cells are resident/tissue specific and are only able to give rise to a stem cell and a daughter cell with refined fate that can only become that specific tissue. They maintain a healthy tissue balance.
Germ cells are set aside in embryogenesis and are what the next generation of an organism is formed from (egg and sperm precursors)
How is the germline set up in C. Elegans? What are the most importnat principles here and how does c elegans comply with them?
Set aside by asymmetric division of cell contents, P-granules are always restricted to one clee only
P-granules attach to other tfs and repress the transcription of other genes (eg PIE1) others block translation, some induce cell division, survival signals and meiosis
A germ cell must be protected from differentiation signals (no trnascrip no reply), be able to perform meiosis, and be totipotent.
In contrast to c.elegans, what happens in drosophila, chick and xenopus germ cell development? Similarities/differences?
In all: germ cells determined before gastrulation, located posteriorly.
In droso, in synsicium pole cells secrete pole-granules and form pole plasm blocking transcription eg germ cell less gene causing impotency when off
In Xeno Nanos is found to be a transcription blocker
In chick germ cells are post on primitive streak
In mammals PHC are located extraembryonically
Describe how germ cells reach their destination when they start extraembryonically!
When pattern set up, eg in Droso post hyper extension, cells attach to ingressing posterior gut
In xeno they are located close to the dorsal lip and they hitch a ride in. They dissociate and attach to different cells to migrate to the lower abdomen
In humans the mesonephron is involved in their formationa s well
Define stem cells!
Cells with unrestricted potential and capability for endless renewal giving rise to daughter cells identical to the mother cells. Both daughter cells are equally potent in adopting a multitude of fates.
(Problematic statements)
What is the function of embryonic stem cells? What about adult ones?
Embryonic stem cells supply the massive expansion and differentiation of the embryo. At the earliest stage, a single cell is capable of enough renewal to supply a whole organism.
Adult stem cells are resident/tissue specific and are only able to give rise to a stem cell and a daughter cell with refined fate that can only become that specific tissue. They maintain a healthy tissue balance.
Germ cells are set aside in embryogenesis and are what the next generation of an organism is formed from (egg and sperm precursors)
How is the germline set up in C. Elegans? What are the most importnat principles here and how does c elegans comply with them?
Set aside by asymmetric division of cell contents, P-granules are always restricted to one clee only
P-granules attach to other tfs and repress the transcription of other genes (eg PIE1) others block translation, some induce cell division, survival signals and meiosis
A germ cell must be protected from differentiation signals (no trnascrip no reply), be able to perform meiosis, and be totipotent.
In contrast to c.elegans, what happens in drosophila, chick and xenopus germ cell development? Similarities/differences?
In all: germ cells determined before gastrulation, located posteriorly.
In droso, in synsicium pole cells secrete pole-granules and form pole plasm blocking transcription eg germ cell less gene causing impotency when off
In Xeno Nanos is found to be a transcription blocker
In chick germ cells are post on primitive streak
In mammals PHC are located extraembryonically
Describe how germ cells reach their destination when they start extraembryonically!
When pattern set up, eg in Droso post hyper extension, cells attach to ingressing posterior gut
In xeno they are located close to the dorsal lip and they hitch a ride in. They dissociate and attach to different cells to migrate to the lower abdomen
In humans at this stage SC migrate over to the gonadal niche forming in the mesonephron along a fibronectin rich pathway using integrins + guided by Sdf1 chemoattractants
What are the characteristics of a stem cell niche and why are they important when culturing in vitro?
Niches present cells with a complex environment balancing out cell proliferation and differentiation giving the SC signals to survive but not to prolif or diff.
In vittro these signals are important to prevent terratomic proliferation (massive unorganised cancer of all cell types) and ro keep the SC in an SC state.
How are tissue specific stem cells kept alive for so long? How long do they last?
Tissue specific stem cells are surrounded by mini niches.
No stem cell has truly endless self renewal, they run out of being able to proliferate and create an identical daughter cells around 30-40y. This causes the symptoms of ageing as the cell mass in teh tissue is not replaced when cells die.
What do niches do to keep up the artificial cell environment?
They interact with the surrounding tissues and environmental signals to determine whether the SC need to be activated or they need to be kept dormant.
Curretn science tries to understand this process to be able to culture and control stem cells
What ways does a cell have to show growth?
Cells can enter mitosos, (most common)
Perform cell enlargement (eg after MI cells get bigger to make up for deficit caused by dead cells)
Secretion of extracellular matrtix (eg seen in chondrogenesis -> secreted ECM forms bone mass)
How does differential growth occour first in droso embryo? What separates parts of the embryo in terms of growth?
Mitotic domains are defined by the activation of string genes which in turn activate cdk-s moderating cell division phases. String is first reg-d by maternal genes, but soon zygotic genes directly bind its promoter to reg it. Patterning directly impacts growth making some areas grow more than others.
Mesoderm is the only expression in which a suppressor gene XX is blocking string until gastrulation is complete, bc migrating cells don’t divide very well.
