Investigating cell line identity and gene regulation in a broad array of human hepatocellular carcinoma

Cultured cancer cell lines are a widely used approach in our biology research. Our lab uses several human liver cancer lines to study the role of two amino acid transporters (ASCT2 and LAT1) during growth. To validate the identity of each line for comparative results, a means of positive ID is needed. Short tandem repeat (STR) analysis is a method that uses the polymerase chain reaction (PCR) to examine \u27w\u27 specific DNA regions, called loci, which surround specific genes. Originally used in forensic analysis and paternity testing, STR analysis has recently become incorporated into research laboratories. The reason is due to the estimate that up to one third of published research is thought to be erroneous due to misidentification of cell lines used in biomedical studies. To proactively address this problem, I have embarked on an effort to establish DNA fingerprints for the human cell lines used in my lab\u27s cancer research. The study involves the isolation of genomic DNA from human liver cancer cell lines and subsequent identification of the cell line via STR analysis. The hypothesis is that each cell line investigated will yield a unique DNA fingerprint. Genomic DNA was isolated, processed, and submitted to an STR analysis core facility for data acquisition. The data presented will reflect my conclusions draw

La qualité du lait chauffé à ultra-haute température comparée à celle du lait pasteurisé et stérilisé dans la bouteille

International audienc

SDS-PAGE analysis of soluble proteins in reconstituted milk exposed to different heat treatments

This paper deals with the investigation of the impact of the heat treatment of reconstituted skim milk conducted at different temperatures, and the adding of demineralized whey on the protein solubility, soluble protein composition and interactions involved between proteins in a chemical complex. Commercial skim milk has been reconstituted and heat treated at 75 degrees C, 85 degrees C and 90 degrees C for 20 minutes. Demineralized whey has been added in concentrations of 0.5%, 1.0 and 2.0%. The soluble protein composition has been determined by the polyacrilamide gel electrophoresis (SDS-PAGE) and by the densitometric analysis. Due to the different changes occurred during treatments at different temperatures, proteins of heat-treated samples containing added demineralized whey have had significantly different solubility. At lower temperatures (75 degrees C and 85 degrees C) the adding of demineralized whey decreased the protein solubility by 5.28%-26.41%, while the addition of demineralized whey performed at 90 degrees C increased the soluble protein content by 5.61%-28.89%. Heat treatments, as well as the addition of demineralized whey, have induced high molecular weight complex formation. beta-Lg, alpha-La and kappa-casein are involved in high molecular weight complexes. The disulfide interactions between denatured molecules of these proteins are mostly responsible for the formation of coaggregates. The level of their interactions and the soluble protein composition are determined by the degree of temperature

Physical properties of yogurt fortified with various commercial whey protein concentrates

The effects of whey protein concentrates on physical and rheological properties of yogurt were studied. Five commercial whey protein concentrates (340 g kg−1 protein nominal) were used to fortify milk to 45 g protein kg−1. Fermentation was performed with two different starters (ropy and non-ropy). Resulting yogurts were compared with a control yogurt enriched with skim milk powder. The water-holding capacity of the yogurt fortified with skim milk powder was 500 g kg−1 and ranged from 600 to 638 g kg−1 when fortified with whey protein concentrates. Significant rheological differences have been noticed between the yogurts fortified with different whey protein concentrates, independent of the starter used. Three whey protein concentrates generated yogurts with a behavior similar to the control. The two others produced yogurt with lower firmness (15 g compared with 17 g), lower Brookfield viscosity (6 Pa s compared with 9 Pa s), lower yield stress (2 Pa compared with 4 Pa), lower complex viscosity (13 Pa s compared with 26 Pa s), and lower apparent viscosity (0.4 Pa s compared with 1 Pa s) than the control, respectively. The yogurts with the lowest firmness and viscosity were produced with concentrates which contained the highest amount of non-protein nitrogen fraction (160 g kg−1 versus 126 g kg−1 of the total nitrogen), and the highest amount of denaturation of the whey protein (262 versus 200 g kg−1 of the total nitrogen)

Considérations sur la cinétique chimique de réchauffement du lait à ultra-haute température

International audienc