Methyllysine Reader Plant Homeodomain (PHD) Finger Protein 20-like 1 (PHF20L1) Antagonizes DNA (Cytosine-5) Methyltransferase 1 (DNMT1) Proteasomal Degradation

Inheritance of DNA cytosine methylation pattern during successive cell division is mediated by maintenance DNA (cytosine-5) methyltransferase 1 (DNMT1). Lysine 142 of DNMT1 is methylated by the SET domain containing lysine methyltransferase 7 (SET7), leading to its degradation by proteasome. Here we show that PHD finger protein 20-like 1 (PHF20L1) regulates DNMT1 turnover in mammalian cells. Malignant brain tumor (MBT) domain of PHF20L1 binds to monomethylated lysine 142 on DNMT1 (DNMT1K142me1) and colocalizes at the perinucleolar space in a SET7-dependent manner. PHF20L1 knockdown by siRNA resulted in decreased amounts of DNMT1 on chromatin. Ubiquitination of DNMT1K142me1 was abolished by overexpression of PHF20L1, suggesting that its binding may block proteasomal degradation of DNMT1K142me1. Conversely, siRNA-mediated knockdown of PHF20L1 or incubation of a small molecule MBT domain binding inhibitor in cultured cells accelerated the proteasomal degradation of DNMT1. These results demonstrate that the MBT domain of PHF20L1 reads and controls enzyme levels of methylated DNMT1 in cells, thus representing a novel antagonist of DNMT1 degradation.     

Influence of storage time and nutrient medium on recovery of fibroblast-like cells from refrigerated collared peccary (<Emphasis Type="Italic">Pecari tajacu</Emphasis> Linnaeus, 1758) skin

Animal cloning is a promising technology for biodiversity conservation, and its success depends on the recovery of nucleus donor cells. Specifically for collared peccaries, found sometimes in regions that are difficult to access, the storage at 4–6°C of skin tissues would be an alternative for the conservation of genetic material. Therefore, we aimed to evaluate different storage periods and the presence of a nutrient medium at 4–6°C on the recovery of somatic cells from the skin of collared peccaries. To analyze cell recovery rates, ear explants were distributed in non-refrigerated samples and samples refrigerated for 10, 30, and 50 d in the absence or presence of nutrient medium. All explants were analyzed by histologically and cultured. Only the fragments stored for 50 d without medium showed an increase in the total thickness of skin. Moreover, increased storage period, regardless of the presence of medium, increased the halo number and reduced the metabolic activity. After culture, only the fragments stored without medium for 50 d did not yield any somatic cells. Cells recovered from explants stored for 10 d showed similar characteristics to these recovered from non-refrigerated explants, regardless of the presence of medium, including the day at which explants achieved attachment and the total time to reach subconfluence. In conclusion, viable cells can be recovered from somatic tissues of collared peccaries stored for up to 50 d in the presence of medium, and tissues refrigerated for up to 10 d in the presence of medium yielded more viable cells.     

Non-isothermal kinetic modelling of potassium indigo-trisulfonate dye discolouration by Horseradish peroxidase

Abstract

Textile industries account for two-thirds of the total dyestuff market been responsible for the production of a large volume of effluent with unfixed dye. Aromatic dyes as potassium indigo-trisulfonate dye (PIT) are characterized as a chemically stable and complex molecule with high heat and light stability and with high toxicity even at low concentration. In order to evaluate an environmentally friendly method to remove potassium indigo-trisulfonate dye from aqueous solution, a commercial peroxidase (horseradish peroxidase, HPR) was used in the experimental and the data were modelled by the Arrhenius equation. According to the results, the best reaction conditions were obtained using 80?mg.L^?1 of dye concentration, 45?°C, pH 5.0, 349.35?U.mL^?1, and 4.5?mM hydrogen peroxide concentration leading to a 96% of dye discolouration.