[Investigation of benzo(a)pyrene contamination in edible vegetable oil sold in Henan Province from 2017 to 2019].

OBJECTIVE: To investigate the contamination of benzo(a)pyrene in edible vegetable oil from Henan Province. METHODS: A total of 1190 edible vegetable oil samples from Henan Province were collected. The concentration of benzo(a)pyrene was examined by high performance liquid chromatography. RESULTS: The concentration of benzo(a)pyrene in prepackaged edible vegetable oils was <0. 3-63. 5 µg/kg with an average of 1. 5 µg/kg. The detection rate of benzo(a)pyrene in samples was 80. 0%, and the over standard rate was 0. 6%. In terms of subclasses of vegetable oil, the sesame seed oil samples were most seriously contaminated with benzo(a)pyrene. The risk of the benzo(a)pyrene contamination of sesame seed oil produced by aqueous extraction method was higher than that by mechanical pressed method. The risk of benzo(a)pyrene contamination in sesame seed oil and rapeseed oil increased as the decrease of quality grade. CONCLUSION: The result suggested that the sesame seed oil produced by aqueous extraction method had high risk in benzo(a)pyrene contamination in Henan Province.

Co-expression of MG29 and ryanodine receptor leads to apoptotic cell death: effect mediated by intracellular Ca2+ release.

Perturbation of intracellular Ca2+ homeostasis has been shown to regulate the process of cell proliferation and apoptosis. Our previous studies show that mitsugumin 29 (MG29), a synaptophysin-related protein localized in the triad junction of skeletal muscle, serves an essential role in muscle Ca2+ signaling by regulating the process of store-operated Ca2+ entry. Here we report a functional interaction between MG29 and the ryanodine receptor (RyR)/Ca2+ release channel. The purified MG29 protein enhances activity of the RyR/Ca2+ release channel incorporated into the lipid bilayer membrane. Co-expression of MG29 and RyR in Chinese hamster ovary cells leads to apoptotic cell death resulting from depletion of intracellular Ca2+ stores, despite neither protein expression alone exhibits any significant effect on cell viability. In transient expression studies, the presence of RyR in the endoplasmic reticulum leads to retention of MG29 from the plasma membrane into the intracellular organelles. This functional interaction between MG29 and RyR could have important implications in the Ca2+ signaling processes of muscle cells. Our data also show that perturbation of intracellular Ca2+ homeostasis can serve as a key signal in the initiation of apoptosis.

A short segment of the R domain of cystic fibrosis transmembrane conductance regulator contains channel stimulatory and inhibitory activities that are separable by sequence modification.

The regulatory (R) domain of the cystic fibrosis transmembrane conductance regulator (CFTR) contains consensus phosphorylation sites for cAMP-dependent protein kinase (PKA) that are the basis for physiological regulation of the CFTR chloride channel. A short peptide segment in the R domain with a net negative charge of B9 (amino acids 817-838, NEG2) and predicted helical tendency is shown to play a critical role in CFTR chloride channel function. Deletion of NEG2 from CFTR completely eliminates the PKA dependence of channel activity. Exogenous NEG2 peptide interacts with CFTR to exert both stimulatory and inhibitory effects on the channel function. The NEG2 peptide with sequence scrambled to remove helical tendencies also inhibits channel function, but does not stimulate. Similar results are found for a NEG2 peptide whose helical structure is disrupted by a proline residue. When six of the negatively charged carboxylic acid residues are replaced by their cognate amides, reducing net negative charge to B3, but increasing helical propensity as assessed by circular dichroism, the peptide stimulates CFTR channel function, but does not inhibit. We speculate that the NEG2 region interacts with other cytosolic domains of CFTR to control opening and closing transitions of the chloride channel.