Toxins

This study evaluated the occurrence of ochratoxin A (OTA) in Turkish coffee and its potential health implications under current consumption patterns by analyzing 65 ground and roasted Turkish coffee samples collected across Türkiye. OTA contamination was detected in 53 samples (82%). Based on the mean OTA concentration, the Estimated Daily Intake (EDI) was calculated as 0.1403 ng/kg body weight/day, and health risk characterization was performed using the Margin of Exposure (MOE) approach in accordance with the European Food Safety Authority (EFSA) recommendations for chronic exposure assessment. MOE calculations enabled a refined characterization of health risks under realistic (0.5 cup/day), average (1 cup/day), and high (3 cups/day) consumption scenarios. The MOE values for carcinogenic (neoplastic) effects ranged from 34,450 to 206,847, all exceeding the EFSA reference threshold of 10,000 and indicating a low level of concern for carcinogenic risk associated with Turkish coffee consumption. For non-carcinogenic (non-neoplastic) kidney effects, MOE values ranged from 11,238 to 67,475 across the different consumption scenarios, all exceeding the EFSA reference threshold of 200, indicating a low level of concern for the general population. In conclusion, the findings demonstrate that Turkish coffee consumption does not pose an OTA-related carcinogenic or non-neoplastic health risk for the general population under current consumption patterns. Nevertheless, considering the widespread consumption of Turkish coffee, continued monitoring and strict implementation of control measures throughout the production chain remain advisable to ensure long-term consumer safety.

Alternative splicing of pre-mRNA is a crucial mechanism in gene expression regulation. As a core component of the spliceosome, the biological function of the Skip protein in Aspergillus flavus remains unknown. Quantitative real-time PCR (qPCR) analysis revealed the presence of two skip gene copies in A. flavus. Single-copy deletion of Skip resulted in slowed growth, reduced conidiation, abolished sclerotial formation, increased aflatoxin biosynthesis, and diminished crop colonization. Meanwhile, Skip was found to regulate the oxidative stress response by modulating the alternative splicing of yapA. Subsequently, immunoprecipitation and Western blot analyses identified lysine 325 (K325) as the benzoylated site on the Skip protein, which catalyzed by the acyltransferase EsaA. Mutation of benzoylated site K325 directly impaired fungal morphogenesis, pathogenicity, and stress adaptation. These findings established the crucial role of Skip and its benzoylation in A. flavus and suggested a potential target for controlling its infection in important crops.

ADP-ribosylation of nucleic acids is a modification found in both eukaryotes and bacteria, where it contributes to genome maintenance but can also serve as a toxic mechanism used by bacterial toxins to disrupt essential cellular processes. This modification is catalysed by ADP-ribosyltransferases and can be reversed by antagonistic ADP-ribosylgylcohydrolase enzymes. To date, ADP-ribosylation of nucleic acid bases has been described only for adenosine, guanosine, and thymidine. Here we report the ADP-ribosylation of cytidine, catalysed by members of the pierisin family of bacterial toxins—ScARP (SCO5461) and Scabin. We also show that ADP-ribosylation of cytidine is reversible through removal by certain NADAR family proteins, including NADAR proteins from the bacterium Streptomyces coelicolor (SCO5665) and the sponge Amphimedon queenslandica, as well as YbiA-type NADAR proteins. The conservation of cytidine de-ADP-ribosylating activity of NADAR proteins across phylogenetically distant species suggests that this modification may have important physiological significance.