What exactly are
Wolbachia and how do
we know if an insect is
infected with them?
Feminization, Parthenogenesis and C.I.,
oh my!
Wolbachia are
Important!! Wolbachia are
intracellular
parasites
inherited via infected eggs.
Feminization – Somehow, maybe
by influencing hormone levels,
Wolbachia cause developing male
woodlice to be born as female.
Wolbachia-infected wasp embryo
Parthenogenesis-inducing –
In wasps and some other arthropods, females are
diploid (result of fertilization) and males are
haploid (develop from unfertilized eggs). Wolbachia prevent chromosome division so eggs
remain diploid, resulting in all female births.
Cytoplasmic Incompatibility (CI) –
Infected females can reproduce with any mate
whereas uninfected females are restricted to
breeding with fewer uninfected males.
Q. How might
Wolbachia affect
gene flow in a
population?
How might this
lead to
sympatric
speciation?
Bacteria “fishing”
DNA sequence
DNA
Replicatiton
What do we use to “hook” Wolbachia DNA?
Primers – a strand of RNA that serves as
the starting point for DNA replication.
WSPEC-F (5’-CATACCTATTCGAAGGGATAG-3’)
WSPEC-R (5’-AGCTTCGAGTGAAACCAATTC-3’)
DNA copies
What gene (DNA)
is being copied
using PCR?
PCR + primer animation :
http://nitro.biosci.arizona.edu/c
ourses/EEB105/lectures/DNA_
replication/DNA_rep.html
Use primers in PCR to help copy DNA (animation) http://www.wiley.com/legacy/college/boyer/0470003790/animations/pcr/pcr.htm
http://www.mcb.harvard.edu/Losick/images/TromboneFINALd.swf
Objective: Use primers to copy the 16S rDNA gene in Wolbachia bacteria
Bacterium
Ribosome
with ribosomes synthesizing a protein
16S rDNA gene – codes for making SSU rRNA
Forward primer
5’
Conserved region
Reverse primer
Variable regions
3’
F
R
Copied DNA (using PCR)
Campbell & Reece, 6th Ed.
Loops
(sites that are more
free to mutate &
evolve faster)
http://en.wikipedia.
org/wiki/Image:10_
small_subunit.gif
Atomic structure of the small subunit a ribosome.
The rRNA, shown in orange, helps match the
mRNA (codon) to the tRNA (anticodon).
Stems (sites that
rarely mutate &
are conserved)
Small subunit ribosomal RNA
http://en.wikipedia.org/
wiki/Ribosomal_RNA