week 3

Question 1

What is the purpose of transplanting a region of neural tube from a transgenic chick into an unlabelled embryo?

Answer 1

To follow the fates of neural crest cells from this region

Question 2

What do some neural crest cells migrate to form in the gut?

Answer 2

Neurons

Question 3

How is modern lineage tracing achieved?

Answer 3

Cells can be labelled via viral vectors or genetic methods and tracked via computer

Question 4

What is the function of the brainbow recombination system?

Answer 4

Randomly fixes cells with a distinct colour allowing descendants to be tracked

Question 5

What is the aim of the Human Development Atlas (HDA)?

Answer 5

To create comprehensive reference maps of cells during development

Question 6

Why is the Human Development Atlas critical?

Answer 6

It helps understand normal organogenesis, effects of mutations, environmental factors, and infectious agents on human development

Question 7

What can fate maps tell us about germ layers?

Answer 7

They show where tissues of each germ layer come from

Question 8

What anatomical changes can fate maps describe?

Answer 8

Changes in cell behaviour which convert egg into fully formed complex organism

Question 9

What framework do fate maps provide for developmental analysis?

Answer 9

Essential framework for molecular, cellular, genetic analysis of development

Question 10

What information can fate maps not provide?

Answer 10

State of cell determination

Question 11

What is another limitation of fate maps?

Answer 11

They cannot tell when a cell becomes determined

Question 12

What molecular factors do fate maps fail to identify?

Answer 12

Molecular factors responsible for cells’ fate

Question 13

Fill in the blank: Fate maps allow the description of anatomical changes in terms of changes in _______.

Answer 13

cell behaviour

Question 14

processes underlying cellular specification

Answer 14

• many essential processes underlying cellular specification occur during and after gastrulation
• cell movements mean cells are exposed to different environments after gastrulation including different signals from other cells
• reprograms inter-cellular information transfer

Question 15

internal vs external information

Answer 15

• cloning experiments demonstrate that genetic information is maintained throughout development : nucleus of a differentiate cell is able to make an entire organism f implanted to enucleated egg
• instead development proceeds cells begins to turn on or off different sets of genes, leading to cell specification and differentiation : Differential gene expression

Question 16

summary

Answer 16

• during development cells become progressively more restricted in their fates by a process of differential gene expression
• no genetic information is lost
• cell integrate internal information and external information to acquire their fate
• frog egg is divided along plane of first cleavage into two blastomeres, each of which gets half of Gray crescent
• transplantation of dorsal lip tissue into ventral epidermis of another embryo induces a secondary embryonic axis
• organiser is specified by a dorsal signal mainly beta cetaninin and vegetal signal
• act synergistically to create gradient of Xnr genes, highest in dorsal region and other wise specificizing types of mesoderm