Developmental Genetics and age of mutants IIA
zygotic vs maternal effect phenotypes
based on mom, must be homozygote dominant mutant for offspring to express trait
drawbacks
only works in few animals or plants
need sort generation time and easy lab culture
redundancy
genes in parallel don't show phenotype until entire set knocked out
pleiotropy
genes are invovled many tissues, hard to implicate one
many mutant embryos die
logic of developmental genetics
enough genetic info, specific gene disrupted can be indetified and studied molecularly
requires no previous information
A) loss of function reveals normal functionc
reverse genetics and knockouts
developmental genetics in Drosophila
maternal acting genes that control earliest stage sof development
characterized homeotic genes that act later in development
genomic equivalence
genes act in both early and late stages of development
showed genes are regulated differently in different cell types during devlopment
still question of nature vs nurture
experiments to prove
cloning of somatic nuclei
albino parents of nucleus donor to wild type donor of enucleated eggs
are all albino
regeneration experiments
loss of limbs of salamanders
early steps towards developmental genetics
mouse mutation Brachyury
homozygous - die before birth
fly mutations affect wing development
brachyury mutants aka T have defects in posterior part early embryo
disruption of notochord
heterozygoud mice - short tail
background
genes
two demands
how chromosomes indential in every cell type can produce cytoplasm with different properties
needed to show could control earliest most basic phases of development
thought came from cytoplasm
political
tought variations were too subtle
these cytoplasmic factors could control cell fate
