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What Are and what do they do???
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Survive without food?
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Legumes like Nitrogen Fixation.
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Then, why do Nitrogen Fixing bacteria exist?
• To give plants the nitrogen needed to develop and grow to many of our favorite vegetables.
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Nitrogen fixating bacteria has specific genes, Nitrogen Fixing genes (Nifs)
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There are many kinds of Nif Genes!
Such as NifA, NifD, NifK…
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Where are Nifs found?
• In some kinds of bacteria.
Example : Anabaena and Azotobacter.
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Nitrogen Fixation is done through a Nitrogenase complex…
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But due to the complexity of the cofactor, there are three kinds…
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Most Nitrogen fixing bacteria has 1 of the 3,
yet, Anabaena has ALL 3 kinds!!!
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Then… How did Anabaena acquire those different Nitrogen Fixing
genes?
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• First, let us look at the genes of Azotobacter Vinelandii (which is not a cyanobacterium) that contains Nifs and alternatives, Anfs and Vnfs.
• Then, Let us compare its genes to genes of Anabaena.
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• Do you think there is a similarity between their Nifs? How about between Vnfs or Anfs of Azobacter and Nifs of Anabaena?
• Considering that they are all Nitrogen Fixing genes, one would expect one of two possibilities…
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All Anabaena genes evolved from the same ancestor, while Azotobacter is different…
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Or…All Nif genes in Anabaena evolved from the same ancestor, while Vnf evolved from same ancestor as for Vnf in Azotobacter
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How do we compare them?
• To understand where it all came from, a TREE must be constructed to compare Azotobacter gene sequence with Cyanobacter gene sequence.
• By Run-Phylip, or Make-Tree
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Go to biolingua…
• Bring genes of Azotobacter to biolingua.
• BLAST them against Cyanobacteria
• Add them together, then ALIGN.
• Finally, make a tree.
• Giving the following actual results…
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So, how did Anabaena acquire those different Nitrogen Fixing
genes?
• Anabaena genes and Azotobacter genes can share the same ancestors:
Maybe.• Anabaena genes and Azotobacter genes don’t
share the same ancestors:
Most likely the case.
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• In order to answer this complex question, further research must be done on this topic to provide enough supporting evidence.
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Special Thanks to…
• Dr. Teresa Thiel Associate Dean, College of Arts and Sciences Professor of Biology Department of Biology University of Missouri-St. Louis
…And…• Dr. Jeff Elhai
Dept. of Biology and Center for the Study of Biological ComplexityVirginia Commonwealth University