No abstract

Meiotic defects derived from incorrect DNA repair during gametogenesis can lead to mutations, aneuploidies and infertility. The coordinated resolution of meiotic recombination intermediates is required for crossover formation, ultimately necessary for the accurate completion of both rounds of chromosome segregation. Numerous master kinases orchestrate the correct assembly and activity of the repair machinery. Although much less is known, the reversal of phosphorylation events in meiosis must also be key to coordinate the timing and functionality of repair enzymes. Cdc14 is a crucial phosphatase required for the dephosphorylation of multiple CDK1 targets in many eukaryotes. Mutations that inactivate this phosphatase lead to meiotic failure, but until now it was unknown if Cdc14 plays a direct role in meiotic recombination. Here, we show that the elimination of Cdc14 leads to severe defects in the processing and resolution of recombination intermediates, causing a drastic depletion in crossovers when other repair pathways are compromised. We also show that Cdc14 is required for the correct activity and localization of the Holliday Junction resolvase Yen1/GEN1. We reveal that Cdc14 regulates Yen1 activity from meiosis I onwards, and this function is essential for crossover resolution in the absence of other repair pathways. We also demonstrate that Cdc14 and Yen1 are required to safeguard sister chromatid segregation during the second meiotic division, a late action that is independent of the earlier role in crossover formation. Thus, this work uncovers previously undescribed functions of the evolutionary conserved Cdc14 phosphatase in the regulation of meiotic recombination.

Meiotic defects derived from incorrect DNA repair during gametogenesis can lead to mutations, aneuploidies and infertility. Effective and coordinated resolution of meiotic recombination intermediates is necessary to accomplish both rounds of successful chromosome segregation. Cdc14 is an evolutionarily conserved dual-specificity phosphatase required for mitotic exit and meiotic progression. Mutations that inactivate the phosphatase lead to meiotic failure. Here, we have identified previously unseen roles of Cdc14 in ensuring correct meiotic recombination. We found that aberrant recombination intermediates accumulate during prophase I when Cdc14 protein levels are drastically reduced. Furthermore, Cdc14 plays a role in suppressing the formation of non-allelic (ectopic) recombination products. We also demonstrate that Cdc14 is required for correct sister chromatid disjunction during the second meiotic divisions. Finally, Cdc14 is required in meiosis for the timely activation of the conserved Holliday Junction resolvase, Yen1/GEN1 in anaphase II. Based on these new findings we propose an early function for Cdc14 in meiotic recombination independent of its later roles during anaphase I/II. 2 Author SummaryMeiotic recombination is fundamental for sexual reproduction, effective and coordinated resolution of recombination intermediates is critical for correct chromosome segregation. Homologous recombination is initiated by the introduction of programmed DSBs followed by the formation of complex branched DNA intermediates, including double Holliday Junctions (dHJs). These recombination intermediates are eventually repaired into crossover or non-crossover products. In some cases, unresolved recombination intermediates, or toxic repair products, might persist until the metaphase to anaphase transition, requiring of a subset of late-acting repairing enzymes to process them.Unrestrained activity of these enzymes might equally put at risk the genome integrity, thus, several layers of regulation tightly control them. For example, in budding yeast meiosis, Yen1/GEN1 is only activated during the second meiotic division, although how it is activated is unknown. Here, we have identified the requirement of the Cdc14 phosphatase for the timely activation of Yen1 during the second division in meiotic cells. Additionally, we have been able to identify a previously undescribed role of Cdc14 in meiotic recombination. Strikingly, we found that levels of aberrant recombination intermediates accumulate during prophase I in cdc14 meiotic deficient cells. Furthermore, in the absence of Cdc14 activity, there is an increase of ectopic recombination products, indicating that Cdc14 plays a direct role in monitoring meiotic DSB repair, possibly in a way independent of Yen1. Such accumulation of persistent recombination intermediates is not sensed by the checkpoint machinery at the end of prophase I, and their abnormal accumulation in cdc14 meiotic cells likely contribute to the missegregation problems observed during the second meiotic division.

Liposomes made of partially purified phospholipids (PL) from Argentine red shrimp waste oil were loaded with two antioxidant lipid co-extracts (hexane-soluble, Hx and acetone-soluble, Ac) to provide a higher content of omega-3 fatty acids. The physical properties of the liposomes were characterized by Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and Differential Scanning Calorimetry (DSC). The antioxidant and anti-inflammatory activity of the lipid extracts and liposomal suspensions were evaluated in terms of Superoxide and ABTS radical scavenging capacities and TNF-α inhibition. Uni-lamellar spherical liposomes (z-average ≈ 145 nm) with strong negative ζ potential (≈ −67 mV) were obtained in all cases. The high content of neutral lipids in the Hx extract caused structural changes in the bilayer membrane and decreased entrapment efficiency regarding astaxanthin and EPA + DHA contents. The liposomes loaded with the Hx/Ac extracts showed higher antioxidant and anti-inflammatory activity compared with empty liposomes. The liposomal dispersions improved the physical and oxidative stability of water-in-oil emulsions as compared with the PL extract, inducing pronounced close packing of water droplets. The liposomes decreased hydroperoxide formation in freshly made emulsions and prevented thio-barbituric acid-reactive substances (TBARS) accumulation during chilled storage. Liposomes from shrimp waste could be valuable nanocarriers and stabilizers in functional food emulsions.