Schol Biol: Genetics

Dr. Victoria Metcalf, Rm RFH046, victoria.metcalf@lincoln.ac.nz x30628

Schol Biol

Schol Question 2012

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Prokaryotes vs. eukaryotes Full genetic potential is never realised concomitantly Adapter molecules (tRNA) involved to bridge information

transfer gap between mRNA and amino acids

Fig. 15-3, p. 305Biology, Russell et al

11 944 climate abstracts from 1991-2011 analysed

A natural laboratoryPolar 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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RS report 2005 (Figures courtesy Scott Doney, Woods Hole Oceanographic Institution)

RHS Wikimedia Commons

Ocean Acidification

Relative proportions of the three inorganic forms of CO2 dissolved in seawater.Green arrows indicate narrow oceanic range of pH at present

LGM176620072100

Wikimedia Commons

Where it happens

Integrative biology

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

Sentinel Antarctic benthic bivalves (circum Antarctic)• Laternula elliptica• Adamussium colbecki

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).

Rod Budd, NIWARod Budd, NIWA

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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 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 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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