1. Hunting down the Alien (gene)!
Lavanya Rishishwar
School of Biology

2. Primary Objectives HGT PAI An understanding of HGT
Methods of analyzing HGTs
Finding candidate HGT regions in a genome
PAI
An understanding of PAI
Searching for PAIs using PAIdb and PAI Finder

3. Horizontal Gene Transfer (HGT)
Part - I
Horizontal Gene Transfer (HGT)

4. What is the science that studies vertical transfer of genes?
Introduction
HGT, also known as Lateral Gene Transfer (LGT), is the transfer of genetic material between organisms other than through vertical gene transfer
They are “alien” regions in the genome (chromosome or plasmids)
What is the science that studies vertical transfer of genes?

5. Mechanisms

6. Why they are interesting?
Bacteria can steal a beneficial gene that arose in another cell instead of waiting for it to evolve, e.g.
Antibiotic Resistance
Pathogenecity
If a bacterium loses a gene, it can reacquire it through HGT

7. Why they are interesting?
There is a limit to which it can acquire these genes: Bigger the genome, slower the replication
LGT may not always be functional:
Non-coding LGT
Duplicate copy
Requires other genes
Might disrupt a gene at the insertion site
Might interfere with existing function
Acquiring a selfish gene – e.g. a viral insertion

8. How can we detect them?

9. Pathogenicity Islands
Part - II
Pathogenicity Islands

10. Introduction
HGT!
They are mobile genetic elements that confer virulence to a pathogen
Could be located on the chromosome or the plasmid

11. PAIdb and PAI Finder

12. Part - III
Utility

13. An example