Chicks (Gallus gallus) Flashcards
Scientific name for chicks
Gallus gallus
Artificial incubation dates back to ______
18th dynasty in Egypt
First recorded observations ______
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
Is the chick genome sequenced?
Yes, genome was published in 2004 (3 years after human genome was published)
NP: J. Michael Bishop and Harold E. Varmus discovered _____.
discovery of the cellular origin of retroviral oncogenes using chick as model system
All NP (list important findings x 10)
1989 Varmus, Bishop…Cellular origin of retroviral oncogenes
- ..Levi-Montalcini, Cohen Nerve growth factor and epidermal growth factor
- ..Baltimore*, Dulbecco, Temin Interaction between tumor viruses and genetic material
- ..de Duve, Palade, Claude Structural and functional organization of cells
- ..Harttline, Granit, Wald Primary physiological and chemical processes of vision
- .. Burnet, Medawar Discovery of acquired immunological tolerance
- ..Theiler…Discoveries concerning yellow fever
- ..Dam, Doisy Discovery of function of vitamin K
- ..Eijkman, Hopkins Discovery of antineuritic and growth stimulating vitamins
- ..Carrel, Alexis Transplantation of blood vessels and organs
Major advantages
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)
Disadvantages
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.
Chick life cycle (4 stages)
cleavage, gastrulation, organogenesis, hatching
Chick development
Fertilization (sperm stored for several weeks)…….Laying (60,000cells at blastoderm stage)
Fertilized, Unincubated egg
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
What is the staging of development called?
Hamburger-Hamilton Staging
Important features of stage 5
has primitive streak with Hensen’s node
Important features of stage 7
we see neural fold and first set of somites
Important features of stage 10
we see more somites, three components of brain and CNS development, heart tube
Important features of stage 17
we see limb buds
Important features of stage 22-25
we see eye pigment showing, limb buds are as long as they are wide
Important features of stage 36-37
elbows and knees more easily identified, beak development and length
Important features of stage 37-39
have feathers
Important features of stage 44-45
we see more feathers, length increase, beak size increase, nervous system extensively developed during this period…day 21 they hatch
Easy embryo access
remove some liquid to drop embryo lower to allow us to cut top egg shell
Long-term cultivation of chick embryos (compare in shell and out of shell)
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
Shell-less culture methods
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
Microsurgical manipulations
–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
tissue transplantation
- -instructive and permissive tissue interactions
- -cell commitment and determination
- -cell lineage
ex. limb morphology
chick-quail chimeras
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
Gene transfer technology
▪Directly address gene function
- -gain-of-function
- -loss-of-function
▪Directly address gene regulation
▪Easily control expression spatially and temporally
Gene transfer (viral vs non-viral)
▪Viral
- -Adenovirus
- -Retrovirus
▪Non-viral
- -Nuclear micro injection (post-mitotic cells)
- -Calcium phosphate
- -Lipofection
- -Naked plasmid DNA injection
- -Particle bombardment
- -Electroporation
Can used ____ as a model for human ___
fertilized eggs, cancer
