No abstract

Pulsed light (PL) inactivation of two human norovirus (HuNoV) surrogates, murine norovirus (MNV-1) and Tulane virus (TV), and two bacterial pathogens, Escherichia coli O157:H7 and Salmonella, were evaluated. The viruses and bacteria were suspended in phosphate buffered saline (PBS) to final populations of ∼6 log PFU/mL and ∼6 log CFU/mL, respectively. Both viral and bacterial suspensions were then irradiated by PL for different durations and the reductions of each microorganisms were determined. MNV-1 and TV were significantly (P < 0.05) more resistant to PL treatment than Salmonella and E. coli O157:H7 in PBS suspension. MNV-1, Salmonella and E. coli O157:H7 were also inoculated on strawberries and blueberries and the PL inactivation of each microorganism was determined. Lower inactivation of each microorganism was achieved on berry surfaces than in PBS suspension. This study shows that PL can induce rapid inactivation of MNV-1, TV, Salmonella and E. coli O157:H7 in clear suspension with viruses more resistant to PL treatment than bacteria. The efficacy of PL treatment is substantially influenced by food surface structure.

The ability to regulate endogenous gene expression is critical in biological research. Existing technologies, such as RNA interference, zinc-finger regulators, transcription-activator-like effectors, and CRISPR-mediated regulation, though proved to be competent in significantly altering expression levels, do not provide a quantitative adjustment of regulation effect. As a solution to this problem, we place CRISPR-mediated interference under the control of blue light: while dCas9 protein is constitutively expressed, guide RNA transcription is regulated by YF1-FixJ-PFixK2, a blue light responding system. With a computer-controlled luminous device, the quantitative relationship between target gene expression and light intensity has been determined. As the light intensifies, the expression level of target gene gradually ascends. This remarkable property enables sensor-CRISPRi to accurately interrogate cellular activities.

In the past decade, adenosine to inosine (A-to-I) RNA editing, which is catalyzed by adenosine deaminases acting on RNA (ADAR) family of enzymes ADAR1 and ADAR2, has been shown to contribute to the development and progression of multiple cancers; however, very little is known about its role in acute myeloid leukemia (AML) - the second most common type of leukemia making up 31% of all adult leukemia cases. Here, we found that ADAR2, but not ADAR1 and ADAR3, is specifically downregulated in core binding factor (CBF) AML with t(8;21) or inv(16). In t(8;21) AML, RUNX1-driven transcription of ADAR2 transcripts was found to be repressed by the RUNX1-ETO fusion protein. Forced overexpression of two ADAR2-regulated RNA editing targets COPA and COG3 indeed inhibits clonogenic growth of human t(8;21) AML cells. Further in vivo animal studies confirmed that ADAR2 could suppress leukemogenesis of t(8;21) AML through its RNA binding and editing capabilities. Our results suggest a novel RNA editing-mediated mechanism leading to t(8,12) AML.

Strawberry is a healthy fruit with numerous health‐benefit compounds. Unfortunately, it is highly perishable and occasionally can be contaminated with foodborne pathogens. The overall goal of this study is to evaluate pulsed light (PL) processing for disinfection of strawberries, extension of shelf life, and preservation of quality attributes and compounds that are beneficial to health. Preliminary screening of PL conditions based on visual appearance of strawberries was conducted, and 3 PL treatments were identified for full evaluation. Salmonella inoculum was artificially deposited onto the skin of strawberries via spot‐inoculation or dip‐inoculation. The 3 PL treatments slightly reduced the level of inoculated Salmonella on strawberries, ranging from approximately 0.4 to 0.8 log reduction. They also slowed down the visible mold development on strawberries by 2 to 4 days compared with the untreated control. Regarding the natural yeasts and molds, the quality attributes (weight loss and firmness), and the bioactive compounds (total anthocyanin, total phenolics, and total antioxidant activity). The 3 PL treatment showed no significant or negligible difference comparing to the control group. Overall, the 3 PL treatments demonstrated potential in extending the shelf life of strawberries. The quality attributes or the bioactive compounds of strawberries showed no significant or minimal change after these PL treatments. Practical Application Pulsed light (PL) processing for strawberry decontamination and shelf life extension was evaluated. Results demonstrated that PL processing could have the potency to improve strawberry shelf life without significantly affecting the quality and bioactive compounds of strawberries.