Team:Osaka/Tests

Tests

Cell viability

We performed the UV assay. The cells were plated on respective agar plates at different dilutions, air dried, and then exposed to different doses of UV radiation. Plates were wrapped with aluminum foil and incubated in the dark. Colony-forming units were scored after 16h incubation at 37°C. Please check Protocol for details.

recA gene could induce high cell viability. RecA protein has key role of SOS response.

This result revealed that the cell inserted recA gene can get tolerance against DNA damage.

pprM gene could also confer high tolerance to inserted cells.

we expected that all cells inserted each genes could increase its ratio of cell survival, however, two genes, pprI and pprA, couldn't confer tolerance. PprI protein is known as a inducer to genes expression such as recA and pprA. Therefore, expression of only pprI may be ineffective for cell survival. Moreover, inserting heavy gene often causes decline of cell survival.

PprA has a function for repairing DNA damaged with blunt end. UV exposure causes thymine dimer, not related to blunt end. We suggest that pprA gene may have no function for repairing DNA damaged by UV but some repairing function for other types of damage such as by chemicals, of cause, radiation

Fortunately, our result about gene mix(connected each genes) showed high tolerance to UV exposure.

SOS response

we assayed the promoter, precA([http://partsregistry.org/wiki/index.php?title=Part:BBa_J22106 BBa J22106])

Future work

We created some parts (PprI , PprA , PprM , RecA) but did not have time to evaluate them. Also, devices containing 2 or more DNA repair gene should have been constructed and assayed.

Reference

1. 放射線抵抗性細菌の新規DNA修復促進タンパク質 , 佐藤勝也　その他 (2006)
2. PprA: a protein implicated in radioresistance of Deinococcus radiodurans stimulates catalase activity in Escherichia coli, Swathi Kota et al (2006)