Alterations in Synthesis and Repair of DNA during the Development of Loach Misgurnus fossilis.

Leonid Gening,Vyacheslav Tarantul,Ludmila Andreeva,Valentina Nenasheva,Andrei Lakhin,Irina Makarova

doi:10.3390/jdb4010006

Abstract

Using a modified radiolabeled primer extension method (we named this modification misGvA—“misincorporation of G versus A”) we have investigated the DNA synthesis and repair at early and late stages of development of loach Misgurnus fossilis. The misincorporation activity of DNA polymerase iota (Pol ι) in wild-type loach could not be detected by this method at any stage of loach development. In transgenic loach overexpressing human Pol ι we have shown that the bypassing of DNA synthesis arrest after incorporation of mismatched nucleotide by Pol ι (the T-stop) was not associated with this enzyme. Non-transgenic loach larvae are virtually lacking the capacity for error correction of DNA duplex containing a mismatched nucleotide. Such repair activity develops only in the adult fish. It appears that the initial stages of development are characterized by more intensive DNA synthesis, while in terminal stages the repair activities become more prominent. The misGvA approach clearly indicates substantial changes in the DNA synthesis intensity, although the role of particular replicative and repair DNA polymerases in this process requires further study.

Highlights

The DNA of all living organisms is constantly exposed to disturbing factors both exogenous and endogenous in nature [1,2]
We have shown that cellular extracts of loach larvae embryos, in comparison to those of adult fish, have a significantly lower ability to remove the incorrect nucleotide in the process of DNA synthesis and replace it with the correct one
DNA synthesis and repair in cellular extracts allows for the assessment of the integral activity of enzymes involved in the metabolism of DNA

Summary

Introduction

The DNA of all living organisms is constantly exposed to disturbing factors both exogenous and endogenous in nature [1,2]. An effective DNA repair system is indispensable for normal activity of cells of any type of organism. To avoid the deleterious consequence of a stalled replication fork, cells use specialized DNA polymerases to traverse the damage. This process, termed “translesion DNA synthesis” (TLS), gives the cell additional time to repair the damage before the replicase returns to complete genome duplication. In many cases, this damage-tolerance mechanism is error-prone, and cell survival is often associated with an increased risk of mutagenesis and carcinogenesis

Methods

Results

Conclusion