No abstract

Little is known about how the synthesis of mitochondrial phospholipids is integrated into mitochondrial biogenesis in fish or mammals. Glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15) catalyzes the addition of fatty acyl CoA to the sn-1 position of glycerol-3-phosphate, in what is considered the rate-limiting step in phospholipid biosynthesis. Previous studies have shown that mitochondrial volume density increases in oxidative skeletal muscle but not liver of Gasterosteus aculeatus (threespine stickleback) in response to cold acclimation. We hypothesized that maximal activity of GPAT would increase in oxidative skeletal muscle but not liver during cold acclimation, coinciding with mitochondrial biogenesis. GPAT activity was measured in liver and oxidative skeletal (pectoral adductor) muscle of threespine stickleback acclimated to 8°C or 20°C. In addition, mRNA levels of enzymes involved in phospholipid synthesis, including cytidine diphosphodiacylglycerol synthase-1 (CDS1), CDS2, GPAT1, GPAT2 and 1-acylglycerol 3-phosphate acyltransferase-2 (AGPAT2), were quantified in liver and pectoral muscle of stickleback harvested during cold acclimation. GPAT activity and transcript levels of AGPAT2 increased in response to cold acclimation in pectoral muscle but not liver. Transcript levels of GPAT1 increased in liver but not pectoral muscle. Overall our results suggest that the activity of GPAT, and possibly AGPAT as well, increase during cold acclimation and may contribute to mitochondrial phospholipid biosynthesis required for mitochondrial biogenesis.

Hydrogen peroxide (H2O2) is the active ingredient in over‐the‐counter whitening strips for teeth. It has previously been shown to damage certain proteins by making them more susceptible to hydrolysis by proteases. The goal of this project was to characterize the hydrolysis of various proteins with H2O2. Albumin protein was mixed with different concentrations of H2O2 for one hour. The protease trypsin was added and portions were removed and immediately mixed with trichloroacetic acid to precipitate either unhydrolyzed proteins or proteins that were minimally hydrolyzed. After centrifugation, the supernatant, which contains small protein fragments that were released by hydrolysis, was collected and; the total amount was measured using the Lowry assay. The results indicate that even without the protease, there is significant hydrolysis with peroxide and none when the proteins were mixed with water. The amount of hydrolysis correlated with the amount of peroxide. In addition, the amount of hydrolysis in the presence of H2O2 with trypsin greatly exceeded that when only trypsin was present. It was important in this method to inactivate peroxide and efficacy of different metals were tested. This effect was further characterized using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). These results suggest that hydrogen peroxide; even at the concentrations used in whitening strips, can damage protein by promoting hydrolysis. This work was supported by Research and Professional Development Grant from Stockton University.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Americans spend billions of dollars every year on teeth whitening products including whitening strips; the active ingredient is hydrogen peroxide (H2O2). Collagen accounts for 95% of the protein found in the dentin layer of teeth, which lies beneath the enamel. Previous research done in our laboratory has indicated that treatment of teeth with over‐the‐counter whitening strips results in reduced amounts of collagen and hydroxyproline. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) was used on collagen extracted from teeth. For the untreated teeth, the extracted collagen showed the expected molecular weights (MW) on SDS PAGE but these bands were absent for the collagen extracted from treated teeth. For this reason, pure Type I collagen was used and treated either with water or with H2O2 for an hour before pepsin was added. Our results indicate that pre‐treatment of Type I collagen with low concentrations of H2O2 produced a lack of bands at the expected MW for collagen and these bands were present in collagen treated with water. This effect was seen as soon as 10 minutes after H2O2 was added. The impact of adding the protease pepsin was further assessed. These results suggest that hydrogen peroxide, even at the concentration used in the whitening strip, can damage the collagen in the dentin provided that the H2O2 can penetrate to the dentin in the teeth. This work was supported by Research and Professional Development Grant from Stockton University.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The aim was to characterize the effect of over-the-counter whitening strips on proteins in teeth. The active ingredient is Hydrogen Peroxide (H 2 O 2 ). Teeth, either treated or untreated, were dialyzed against 10% EDTA pH 9.0; the dialysis fluid contained all proteins other than collagen and was measured with Lowry assay. Collagen was extracted from the teeth and a modified version of the Lowry assay and hydroxyproline assays were used to measure it. A novel method was developed to measure the protein and collagen released from teeth into the surrounding fluid. The Molecular Weights (MW) of proteins were measured using Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS PAGE). There was a 15% and 37% loss of non-collagen proteins after one and three rounds of treatments. These values were 32% and 55% for collagen and 49% and 80% for hydroxyproline. The MW (70,11 and 130 kDa) of the proteins in these fractions matched those of proteins in teeth. No protein was released from teeth into the surrounding fluid without application of whitening strips but with strips, there was protein. Non-collagen protein averaged 0.2867mg/ml for one round of treatments and 1.240mg/ml for collagen. The MW of proteins released are slightly smaller than those extracted from teeth. Over-the-counter whitening strips resulted in a decrease of non-collagen and collagen protein in teeth. In addition, both types of protein were released from treated teeth; none was observed in untreated teeth.