Chicks (Gallus gallus)

Question 1

Scientific name for chicks

Answer 1

Gallus gallus

Question 2

Artificial incubation dates back to ______

Answer 2

18th dynasty in Egypt

Question 3

First recorded observations ______

Answer 3

included in works attributed to Hippocrates
-Hippocrates texts mentioned view that in the chick, the bird is formed from the yolk and the white is the food, and when there is no food left, it hatches

Question 4

Is the chick genome sequenced?

Answer 4

Yes, genome was published in 2004 (3 years after human genome was published)

Question 5

NP: J. Michael Bishop and Harold E. Varmus discovered _____.

Answer 5

discovery of the cellular origin of retroviral oncogenes using chick as model system

Question 6

All NP (list important findings x 10)

Answer 6

1989 Varmus, Bishop…Cellular origin of retroviral oncogenes

1986. ..Levi-Montalcini, Cohen Nerve growth factor and epidermal growth factor
1987. ..Baltimore*, Dulbecco, Temin Interaction between tumor viruses and genetic material
1988. ..de Duve, Palade, Claude Structural and functional organization of cells
1989. ..Harttline, Granit, Wald Primary physiological and chemical processes of vision
1990. .. Burnet, Medawar Discovery of acquired immunological tolerance
1991. ..Theiler…Discoveries concerning yellow fever
1992. ..Dam, Doisy Discovery of function of vitamin K
1993. ..Eijkman, Hopkins Discovery of antineuritic and growth stimulating vitamins
1994. ..Carrel, Alexis Transplantation of blood vessels and organs

Question 7

Major advantages

Answer 7

Fertilized eggs are cheap and available in large numbers all year round

Development is fast in comparison with most mammalian embryos -generation time (i.e. egg to adult = around 60days )

Enormous bibliography concerning system and organ development

Development resembles that of mammals

Genome is 1/3 size of human (but roughly same # genes)

Comparatively large size = microsurgical manipulations readily performed

Embryos readily accessible between laying (i.e. blastoderm stage) and hatching (~21 days)

Question 8

Disadvantages

Answer 8

Preblastodermal/germinal disc stages not easily accessible

Little genetics (little ways to manipulate them because we don’t usually do that type of research in chickens)

Production of transgenic chickens laborious and expensive

Molecular tools are rare for PCR kits, primers, etc.

Question 9

Chick life cycle (4 stages)

Answer 9

cleavage, gastrulation, organogenesis, hatching

Question 10

Chick development

Answer 10

Fertilization (sperm stored for several weeks)…….Laying (60,000cells at blastoderm stage)

Question 11

Fertilized, Unincubated egg

Answer 11

A blastoderm is a single layer of embryonic epithelial tissue that makes up the blastula. It encloses the fluid filled blastocoel.

Gastrulation follows blastoderm formation, where the tips of the blastoderm begins the formation of the ectoderm, mesoderm, and endoderm

Question 12

What is the staging of development called?

Answer 12

Hamburger-Hamilton Staging

Question 13

Important features of stage 5

Answer 13

has primitive streak with Hensen’s node

Question 14

Important features of stage 7

Answer 14

we see neural fold and first set of somites

Question 15

Important features of stage 10

Answer 15

we see more somites, three components of brain and CNS development, heart tube

Question 16

Important features of stage 17

Answer 16

we see limb buds

Question 17

Important features of stage 22-25

Answer 17

we see eye pigment showing, limb buds are as long as they are wide

Question 18

Important features of stage 36-37

Answer 18

elbows and knees more easily identified, beak development and length

Question 19

Important features of stage 37-39

Answer 19

have feathers

Question 20

Important features of stage 44-45

Answer 20

we see more feathers, length increase, beak size increase, nervous system extensively developed during this period…day 21 they hatch

Question 21

Easy embryo access

Answer 21

remove some liquid to drop embryo lower to allow us to cut top egg shell

Question 22

Long-term cultivation of chick embryos (compare in shell and out of shell)

Answer 22

1) culture of embryos in the shell
- -protected
- -optimal physio-chemical conditions
- -shell is important source of calcium for building skeletal elements

2) shell-less culture
- -easily visible
- -more readily accessible to manipulation

Question 23

Shell-less culture methods

Answer 23

incubate until day 5 to see embryo development and membrane, day 8 shows eye development, day 14 vasculature gets extensive, day 15 you can use for imaging

Question 24

Microsurgical manipulations

Answer 24

–readily performed in ovo until about embryonic day 9/10
(all major patterning events complete and all organ systems established)

–shell-less culture facilitates access

Ex. tissue transplantation, chick-quail chimeras

Question 25

tissue transplantation

Answer 25

• -instructive and permissive tissue interactions
• -cell commitment and determination
• -cell lineage
  ex. limb morphology

Question 26

chick-quail chimeras

Answer 26

Host and donor chicken, crack them, cut out quail cells (morphologically different), see that quail cells have more chromosome condensation, can use for linear tracing

Question 27

Gene transfer technology

Answer 27

▪Directly address gene function

• -gain-of-function
• -loss-of-function

▪Directly address gene regulation

▪Easily control expression spatially and temporally

Question 28

Gene transfer (viral vs non-viral)

Answer 28

▪Viral

• -Adenovirus
• -Retrovirus

▪Non-viral

• -Nuclear micro injection (post-mitotic cells)
• -Calcium phosphate
• -Lipofection
• -Naked plasmid DNA injection
• -Particle bombardment
• -Electroporation

Question 29

Can used ____ as a model for human ___

Answer 29

fertilized eggs, cancer