Effect of active phenolic acids on properties of PLA-PHBV blend films

[EN] Phenolic acids (ferulic, p-coumaric, and protocatechuic) have been incorporated into polylactic (PLA): Poly(3hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) (75:25) blend films that were obtained by melt-blending and compression moulding, using PEG1000 as a plasticizer. Film microstructure, thermal behavior, functional properties, and release kinetics of phenolic acids in different food simulants were analyzed, and the film antimicrobial activity against Listeria innocua. Phenolic acids led to an increase in the glass transition temperature of PLA while PHBV supercooling occurred in the films containing protocatechuic acid, which affected their thermal degradation behavior. Polymer matrices with phenolic acids were stiffer and more resistant to break than the polyester blend, but with similar extensibility, while oxygen and water vapor barrier capacity were also improved, especially in films containing protocatechuic acid. The release rate and ratio of phenolic acids increased when the polarity of the food simulant decreased, although very slow delivery was observed in all cases. The limited release of active compounds in aqueous media provoked that films did not significantly inhibit the growth of Listeria innocua in inoculated culture medium.Acknowledgements The authors would like to thank the Ministerio de Ciencia e Innovación of Spain, for funding this study through the Project AGL2016-76699-R and PID2019-105207RB-I00, and the predoctoral research grant #BES-2017-082040.Hernandez-Garcia, E.; Vargas, M.; Chiralt, A. (2022). Effect of active phenolic acids on properties of PLA-PHBV blend films. Food Packaging and Shelf Life. 33:1-11. https://doi.org/10.1016/j.fpsl.2022.1008941113

Paternity allocation in a mutant Heliothis virescens colony

Tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), females can copulate multiple times creating the possibility for sperm competition. We used a colony lacking wild pigmentation on the wings (albino-type) for an experiment in which females double mated. Females copulated 2 days apart with two, 2-day-old males, one albino-type and one wild-type, or in the opposite sequence. A third of the females produced offspring from the first mate, and this group was significantly biased toward producing albino-type compared to wild-type progeny. A fourth of the females produced offspring from the second male exclusively and within this group was a significant bias toward wild-type compared to albino-type progeny. Almost half of the females produced offspring sired in equal proportions by both males simultaneously or in alternated paternities throughout all the reproductive life. These results suggest that regardless of the order in which moths mated, wild-type sperm had potential superior competitiveness. Therefore, sperm precedence is not the main driving force behind the paternity allocation mechanism in this strain of tobacco budworm

Reducing complexity: An iterative strategy for parameter determination in biological networks

AbstractThe dynamics of biological networks are fundamental to a variety of processes in many areas of biology and medicine. Understanding of such networks on a systemic level is facilitated by mathematical models describing these networks. However, since mathematical models of signalling networks commonly aim to describe several highly connected biological quantities and many model parameters cannot be measured directly, quantitative dynamic models often present challenges with respect to model calibration. Here, we propose an iterative fitting routine to decompose the problem of fitting a system of coupled ordinary differential equations describing a signalling network into smaller subproblems. Parameters for each differential equation are estimated separately using a Differential Evolution algorithm while all other dynamic quantities in the model are treated as input to the system. The performance of this algorithm is evaluated on artificial networks with known structure and known model parameters and compared to a conventional optimisation procedure for the same problem. Our analysis indicates that the procedure results in a significantly higher quality of fit and more efficient reconstruction of the true parameters than the conventional algorithm

In vivo Neutralization of Pro-inflammatory Cytokines During Secondary Streptococcus pneumoniae Infection Post Influenza A Virus Infection

An overt pro-inflammatory immune response is a key factor contributing to lethal pneumococcal infection in an influenza pre-infected host and represents a potential target for therapeutic intervention. However, there is a paucity of knowledge about the level of contribution of individual cytokines. Based on the predictions of our previous mathematical modeling approach, the potential benefit of IFN-γ- and/or IL-6-specific antibody-mediated cytokine neutralization was explored in C57BL/6 mice infected with the influenza A/PR/8/34 strain, which were subsequently infected with the Streptococcus pneumoniae strain TIGR4 on day 7 post influenza. While single IL-6 neutralization had no effect on respiratory bacterial clearance, single IFN-γ neutralization enhanced local bacterial clearance in the lungs. Concomitant neutralization of IFN-γ and IL-6 significantly reduced the degree of pneumonia as well as bacteremia compared to the control group, indicating a positive effect for the host during secondary bacterial infection. The results of our model-driven experimental study reveal that the predicted therapeutic value of IFN-γ and IL-6 neutralization in secondary pneumococcal infection following influenza infection is tightly dependent on the experimental protocol while at the same time paving the way toward the development of effective immune therapies

Board 399: The Freshman Year Innovator Experience (FYIE): Bridging the URM Gap in STEM

The project focuses on increasing “effective STEM education and broadening participation” in underrepresented minority STEM students at the University of Texas Rio Grande Valley (UTRGV) to successfully face academic and professional challenges, recently exacerbated by the COVID-19 pandemic. The Freshman Year Innovator Experience proposes the development of self-transformation skills in freshman mechanical engineering students to successfully face academic and professional challenges exacerbated by the COVID-19 pandemic while working on two parallel projects of technical design innovation and academic career pathways. The authors will present the work in progress and preliminary results from a pilot implementation of the Freshman Year Innovator Experience. This project is funded by NSF award 2225247