27 research outputs found
Replication of Diener et al. (2010) at University of Toronto, tut5401, W19
we are a group of students completing this replication for advanced social psychology clas
A Novel Strategy Based on Permanent Protein Modifications Induced by Formaldehyde for Food Safety Analysis
The illegal additions of chemicals
in food products are serious
incidents threatening current public safety. To date, ideal methods
to determine permanent traces of prohibited chemicals in foods are
still lacking. For example, formaldehyde (FA) can be added illegally
as a food preservative. However, most current methods that are dependent
on the direct detection of FA are not able to determine if FA has
ever been added once food products are rinsed completely. Herein,
we present a novel approach relying upon protein modifications induced
by FA (PMIF) to examine FA in foods. We reveal the entire catalog
of PMIFs in food products by combining mass spectrometry analysis
with unrestrictive identification of protein modifications. Consequently,
four obvious PMIFs were identified and confirmed as markers to discriminate
the addition of FA in foods. Our study demonstrates that the approach
based on PMIFs enables detecting the imprinted trace of FA even if
the food products have been washed thoroughly. Our work presents a
novel strategy for analysis of chemical additives, offering broad
potential applications in protein analysis and food safety
Optimization of the Fermentative Production of Rhizomucor miehei Lipase in Aspergillus oryzae by Controlling Morphology
Morphology plays an important role in the fermentation bioprocess of filamentous fungi. In this study, we investigated the controlling strategies of morphology that improved the efficiency of Rhizomucor miehei lipase (RML) production using a high-yield Aspergillus oryzae. First, the inoculated spore concentrations were optimized in seed culture, and the RML activity increased by 43.4% with the well-controlled mycelium pellets in both ideal sizes and concentrations. Then, the initial nitrogen source and agitation strategies were optimized to regulate the morphology of Aspergillus oryzae in a 5 L bioreactor, and the established stable fermentation system increased the RML activity to 232.0 U/mL, combined with an increase in total RML activity from 98,080 U to 487,179 U. Furthermore, the optimized fermentation strategy was verified by a high-yield Aspergillus oryzae and achieved an additional improvement of RML activity, up to 320.0 U/mL. Moreover, this optimized fermentation bioprocess was successfully scaled up to a 50 L bioreactor, and the RML activity reached 550.0 U/mL. This work has established a stable precision fermentation bioprocess for RML production by A. oryzae in bioreactors, and the controlling strategy developed in this study could potentially be extended to an industrial scale for RML production with high efficiency
Analysis of Differentially Expressed Proteins and Modifications Induced by Formaldehyde Using LC-MS/MS
Formaldehyde (FA) is a toxic compound that is considered to have a carcinogenic effect due to its damage to biological macromolecules. However, the influence of FA at the protein level remains to be explored. Here, we used LC-MS/MS to identify the differentially expressed proteins and modifications to proteins between FA-treated and untreated HeLa cells. Among 2021 proteins identified, 196 proteins were significantly down-regulated and 152 up-regulated. The differentially expressed proteins were further analyzed using bioinformatics tools for annotating the characterization of their localizations and functions. To evaluate the interaction of FA with proteins, we performed proteomic analysis for a mass shift of 12 Da on the side chains of lysine, cysteine and tryptophan, which are induced by FA as noticeable signals. We identified the modified proteins and sites, suggesting direct interaction between FA and proteins. Motif analysis further showed the characterization of amino acid sequences that react with FA. Cluster analysis of the modified proteins indicated that the FA-interacting networks are mostly enriched in the nuclei, ribosomes and metabolism. Our study presents the influence of FA on proteomes and modifications, offering a new insight into the mechanisms underlying FA-induced biological effects
How Dirhodium Catalyst Controls the Enantioselectivity of [3 + 2]-Cycloaddition between Nitrone and Vinyldiazoacetate: A Density Functional Theory Study
The origin of enantioselectivity
in the dirhodium-catalyzed [3
+ 2]-cycloaddition of nitrone and vinyldiazoacetate has been investigated
using dispersion-corrected density functional theory. Taking a more
realistic account of bulky ligands in models of the dirhodium catalyst
when investigating its catalytic behavior is crucial for describing
the effects resulting from a high level of asymmetric induction. More
than one active site can be located and the extra reactivity is provided
by an electron-donation interaction between the substrate and an additional
Rh<sub>2</sub>L<sub>4</sub> catalyst