Role of the Polymerase ϵ sub-unit DPB2 in DNA replication, cell cycle regulation and DNA damage response in Arabidopsis

Faithful DNA replication maintains genome stability in dividing cells and from one generation to the next. This is particularly important in plants because the whole plant body and reproductive cells originate from meristematic cells that retain their proliferative capacity throughout the life cycle of the organism. DNA replication involves large sets of proteins whose activity is strictly regulated, and is tightly linked to the DNA damage response to detect and respond to replication errors or defects. Central to this interconnection is the replicative polymerase DNA Polymerase ϵ (Pol ϵ) which participates in DNA replication per se, as well as replication stress response in animals and in yeast. Surprisingly, its function has to date been little explored in plants, and notably its relationship with DNA Damage Response (DDR) has not been investigated. Here, we have studied the role of the largest regulatory sub-unit of Arabidopsis DNA Pol ϵ DPB2, using an over-expression strategy. We demonstrate that excess accumulation of the protein impairs DNA replication and causes endogenous DNA stress. Furthermore, we show that Pol ϵ dysfunction has contrasting outcomes in vegetative and reproductive cells and leads to the activation of distinct DDR pathways in the two cell types. © 2016 The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research

Heterogeneous catalysis for sustainable biodiesel production via esterification and transesterification

Concern over the economics of accessing fossil fuel reserves, and widespread acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from combusting such carbon sources, is driving academic and commercial research into new routes to sustainable fuels to meet the demands of a rapidly rising global population. Here we discuss catalytic esterification and transesterification solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels to meet future societal demands

Function of the plant DNA polymerase epsilon in replicative stress sensing, a genetic analysis

Faithful transmission of the genetic information is essential in all living organisms. DNA replication is therefore a critical step of cell proliferation, because of the potential occurrence of replication errors or DNA damage when progression of a replication fork is hampered causing replicative stress. Like other types of DNA damage, replicative stress activates the DNA damage response, a signaling cascade allowing cell cycle arrest and repair of lesions. The replicative DNA polymerase epsilon (Pol epsilon) was shown to activate the S-phase checkpoint in yeast in response to replicative stress, but whether this mechanism functions in multicellular eukaryotes remains unclear. Here, we explored the genetic interaction between Pol epsilon and the main elements of the DNA damage response in Arabidopsis ( Arabidopsis thaliana). We found that mutations affecting the polymerase domain of Pol epsilon trigger ATR-dependent signaling leading to SOG1 activation, WEE1-dependent cell cycle inhibition, and tolerance to replicative stress induced by hydroxyurea, but result in enhanced sensitivity to a wide range of DNA damaging agents. Using knock-down lines, we also provide evidence for the direct role of Pol epsilon in replicative stress sensing. Together, our results demonstrate that the role of Pol epsilon in replicative stress sensing is conserved in plants, and provide, to our knowledge, the first genetic dissection of the downstream signaling events in a multicellular eukaryote

Batch and Continuous Ultrasonic Reactors for the Production of Methyl Esters from Vegetable Oils

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