Giardia duodenalis carries out canonical homologous recombination and single-strand annealing.

In the past decades, the ability of Giardia duodenalis to perform homologous recombination has been suggested, supported by the observations of genomic integration of foreign plasmids and the disruption of genes using CRISPR technology. Unfortunately, the direct study of a HR mechanism has not been addressed, which would be pertinent in a minimalist organism lacking fundamental DNA-repair elements and even complete pathways. In addition, the constant ploidy changes through the life cycle of this parasite highlight the conservation and relevance of homologous recombination in maintaining genomic stability.

Evidence of requirement for homologous-mediated DNA repair during Ambystoma mexicanum limb regeneration.

Background: Limb regeneration in the axolotl is achieved by epimorphosis, thus depending on the blastema formation, a mass of progenitor cells capable of proliferating and differentiating to recover all lost structures functionally. During regeneration, the blastema cells accelerate the cell cycle and duplicate its genome, which is inherently difficult to replicate because of its length and composition, thus being prone to suffer double-strand breaks.

Results: We identified and characterized two remarkable components of the homologous recombination repair pathway (Amex.

DNA repair during regeneration in Ambystoma mexicanum.

The remarkable regenerative capabilities of the salamander Ambystoma mexicanum have turned it into one of the principal models to study limb regeneration. During this process, a mass of low differentiated and highly proliferative cells, called blastema, propagates to reestablish the lost tissue in an accelerated way. Such a process implies the replication of a huge genome, 10 times larger than humans, with about 65.