Download Horizontal Gene Transfer

Horizontal Gene Transfer: New Gene Acquisition
Transformation: naked DNA
uptake by bacteria
Transduction: bacterial DNA
transferred by viruses
(phage)
Conjugation: DNA transfer
between bacterial cells
Furuya EY and Lowy F (2006) Nat Rev Microbiol. 4: 36–45.
Horizontal Gene Transfer: New Gene Acquisition
– Selfish mechanisms result in genetic diversity
• Often confer properties of virulence, antibiotic
resistance, or metabolic fitness
– May provide different characteristics
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Utilization of energy sources
Acid tolerance
Development of symbiosis
Ability to cause disease
– Pathogenicity islands
Horizontal Gene Transfer: New Gene Acquisition
1. Lyse antibiotic resistant cells
SDS + 60˚C
Why are we using DNA that has an antibiotic
resistant marker?
How are we able to lyse the cells?
DNA component
with antibiotic
resistance
marker gets
released
Horizontal Gene Transfer: New Gene Acquisition
2. Combine free DNA with cells sensitive to the
antibiotic and plate on non-selective media
+
Horizontal Gene Transfer: New Gene Acquisition
3. Plate transformed cells on plates selective for
antibiotic resistance
Horizontal Gene Transfer: New Gene Acquisition
a) DNA only: test that it is
inert/not-alive
b) StrS cells
c) StrR cells
d) 1 loopful StrS cells. Place 1
loopful DNA ON TOP of those
cells
e) 1 loopful StrS cells.
THEN one loopful DNase
THEN one loopful DNA
b) StrS cells
c) StrR cells
d) StrS cells
+ DNA
a) DNA only
e) StrS cells
+ DNase
+ DNA