Linear and cyclic oligomers in polybutylene terephthalate for food contact materials

Polybutylene terephthalate (PBT) is a polyester (PES) gaining more importance on the food contact material (FCM) market. However, little is known about the potential migration of PBT oligomers which are formed during polymer production. In this work, PBT pellets and a slotted spoon manufactured from this material by injection moulding were analysed on extractable oligomers and their migration potential into hydrophilic foods. Overall 27 oligomers (cycles and linears) could be identified in different extracts by HPLC-DAD/ESI-MS data, but without confirmation by reference substances. The oligomers were quantified by HPLC-DAD using bis(2-hydroxyethyl) terephthalate (BHET) as external standard and the total amount of oligomers isolated by reprecipitation from the pellets and the spoon were 0.69 and 0.71%, respectively. While cyclic oligomers made up for approximately 90% of the extractable oligomers, linear oligomers proved to be more relevant for migration into aqueous foodstuffs. Furthermore, it was shown that hydrolysis of oligomers can take place in water at elevated temperatures. Consequently, the qualitative and quantitative composition of PBT oligomers in aqueous foods from FCMs does not only depend on migration but also on hydrolysis. Migration testing of the PBT spoon under repeat use conditions with water at 100°C for 2 h resulted in 0.29 mg item^?1 of linear oligomers and 0.05 mg item^?1 of the cyclic PBT dimer in the third migrate.     

Modulation of GDP-dissociation inhibitor protein membrane retention by the cellular redox state in adipocytes

Genetic screens in zebrafish have provided mutations in hundreds of genes with essential functions in the developing embryo. To investigate the possible uses of chromosomal rearrangements in the analysis of these mutations, we genetically characterized three gamma-ray induced alleles of cyclops (cyc), a gene required for development of midline structures. We show that cyc maps near one end of Linkage Group 12 (LG 12) and that this region is involved in a reciprocal translocation with LG 2 in one gamma-ray induced mutation, cyc(b213). The translocated segments together cover approximately 5% of the genetic map, and we show that this rearrangement is useful for mapping cloned genes that reside in the affected chromosomal regions. The other two alleles, cyc(b16) and cyc(b229), have deletions in the distal region of LG 12. Interestingly, both of these mutations suppress recombination between genetic markers in LG 12, including markers at a distance from the deletion. This observation raises the possibility that these deletions affect a site required for meiotic recombination on the LG 12 chromosome. The cyc(b16) and cyc(b229) mutations may be useful for balancing other lethal mutations located in the distal region of LG 12. These results show that chromosomal rearrangements can provide useful resources for mapping and genetic analyses in zebrafish.