Risk assessment of homologous variants of biotech trait proteins using a bridging approach.

A transgenic protein is frequently expressed as different homologous variants in genetically modified crops due to differential processing of targeting peptides or optimization of activity and specificity. The aim of this study was to develop a science-based approach for risk assessment of homologous protein variants using dicamba mono-oxygenase (DMO) as a case study. In this study, DMO expressed in the next-generation dicamba-tolerant maize, sugar beet and soybean crops exhibited up to 27 amino acid sequence differences in the N-terminus.

Food and feed safety of the Bacillus thuringiensis derived protein Vpb4Da2, a novel protein for control of western corn rootworm.

Western corn rootworm (WCR), Diabrotica virgifera virgifera, LeConte, is an insect pest that poses a significant threat to the productivity of modern agriculture, causing significant economic and crop losses. The development of genetically modified (GM) crops expressing one or more proteins that confer tolerance to specific insect pests, such as WCR, was a historic breakthrough in agricultural biotechnology and continues to serve as an invaluable tool in pest management. Despite this, evolving resistance to existing insect control proteins expressed in current generation GM crops requires continued identification of new proteins with distinct modes of action while retaining targeted insecticidal efficacy.

The aryl hydrocarbon receptor nuclear translocator (Arnt) is required for tumor initiation by benzo[a]pyrene.

Benzo[a]pyrene (B[a]P) is a ligand for the aryl hydrocarbon receptor (Ahr). After binding ligand, Ahr dimerizes with the aryl hydrocarbon receptor nuclear translocator (Arnt) protein, and the dimer upregulates the transcription of Cyp1a1, Cyp1b1 and other enzymes involved in the metabolic activation of B[a]P. Arnt null mice die in utero.

Pulmonary inflammation in mice exposed to mainstream cigarette smoke.

Male C57Bl/6 (C57) and ICR mice were exposed by nose-only inhalation to mainstream cigarette smoke (MS) from 2R4F reference cigarettes, at concentrations of 75, 250, and 600 microg of total particulate matter (TPM) per liter, for up to 6 mo. Respiratory-tract tissue (nose, larynx, and lung), blood, and bronchoalveolar lavage fluid (BALF) samples were collected and analyzed at several time points. Blood samples were analyzed for biomarkers of exposure (COHb and nicotine).