BIOMG 1350 Lecture Notes - Lecture 20: Blastula, Zygote, Microtubule
18 Dec 2016
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● Bitch how is a fruit fly made
○ Easy to grow
○ In little bottles
○ 24 hours to hatch
○ Simple genetics
○ 4 chromosomes
○ 14,000 genes
○ Sophisticated genetic and molecular biology tools
○ Life Cycle
■ Fertilization → hatching in 1 day
■ Pupation in 5 days
■ Metamorphosis in ~9 days
○ Denticles = bristles on larvae that help them crawl
■ Corresponds to the segments in late embryo stage
○ Three segments: Head parts, thorax, abdomen
○ Syncytium=multiple nuclei in a common cytoplasm
■ Communication between nuclei
○ Blastoderm = insect blastula
■ Communication between blastula
○ Contents of an egg
■ Maternal pronucleus/DNA
■ Nutrients (yolk)
■ Transcripts (mRNA) and proteins from the mother
● When fertilized, they are activated
● Run on material encoded by the mother’s genes
○ Different than zygotic genes
○ New zygotic proteins are made, which degrades maternal
products
● Also causes cell division and early asymmetries
■ Maternal-to-zygotic transition in different organisms
● Mammals have minimal influence by maternal genome in
development compared to fruit fly, nematodes, etc.
○ Genetic Control of early embryonic development
○ Egg Polarity Genes
■ Bicoid: missing anterior segments
● Anterior system
● Transcription regulator
■ Nanos: Missing posterior segments
● Posterior system
● Translation regulator
■ Torso: Terminal segment missing
■ These are mutations in maternal genes that causes these effects
■ Follicle cells generate asymmetries
● Have the ability to send signals to oocyte
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