Transcript Schol Biol: Genetics

Schol Biol
Schol Biol: Genetics
Dr. Victoria Metcalf, Rm RFH046, [email protected]
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Schol Question 2012
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Prokaryotes vs. eukaryotes
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Full genetic potential is never realised concomitantly
Adapter molecules (tRNA) involved to bridge information
transfer gap between mRNA and amino acids
Biology, Russell et al Fig. 15-3, p. 305
11 944 climate abstracts from 1991-2011 analysed
A natural laboratory
Polar organisms = ‘canaries in a coal mine’
What can we determine about the evolution of Antarctic marine animals? =
PAST/PRESENT
What is their capacity to adapt to future change? (‘Health check’) = FUTURE
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Ocean Acidification
2100 2007 1766LGM
Relative proportions of the three inorganic
forms of CO2 dissolved in seawater.
Green arrows indicate narrow oceanic
range of pH at present
RS report 2005 (Figures courtesy Scott Doney, Woods
Hole Oceanographic Institution)
RHS Wikimedia Commons
Where it happens
Wikimedia Commons
Integrative biology
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Assessing if there is decreased fitness of calcifying organisms due to
ocean acidification
Predict that the effects of acidification are species dependent, and
linked to location via variations in water temperature and food supply
Granite Harbour
Experimental setup
pCO2 levels of:
• natural environment (430 μatm, pH 7.99)
• predicted for 2100 (735 μatm, pH 7.78)
• glacial levels (187 μatm, pH 8.32).
Vonda Cummings, NIWA
Sentinel Antarctic benthic bivalves (circum Antarctic)
• Laternula elliptica
• Adamussium colbecki
Rod Budd, NIWA
Methods
Physiological parameters
• Respiration (oxygen consumption)
Molecular parameters
• Gene expression changes
• Chitin synthase (shell structure)
• HSP70 (stress)
Biochemical measurements
• Carbonic anhydrase activity
Gene expression studies – the basics
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Genes within DNA are a code for proteins
(proteins do the actual work in our bodies)
In cells, genes are copied into a message form
(messenger RNA/mRNA) to then be used by the
protein making factories (ribosomes)
The copying for any particular gene is switched
on and off as required
Specific target pieces of genetic material can be
copied and amplified using a technology called
polymerase chain reaction or PCR for short
We use a special type of PCR to look at the genes
actually being copied and therefore used at any
one time is:
 Reverse Transcription (RT)-PCR
 Where mRNA is amplified via cDNA synthesis
 cDNA is a stable copy of mRNA (the message)
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Gene expression studies – functional genomics
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qPCR (quantitative or real time PCR) is another special type of PCR
Used to look at the expression of particular genes (RT-qPCR) and assess
how much message template was present (analyse this in real time in
the machine)
Compare the amounts from different treatments (e.g. molluscs exposed
to normal vs. low pH) and reference against the expression levels of one
or more reference genes (these should remain stable no matter what)
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Upregulation of HSP70 expression indicating a stress at both low + high pH
Negative correlation between pH & chitin synthase expression (calcification gene)
What else?
Temperature effects on Antarctic fish and fat saturation levels
The microbiome- humans, other animals
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