Learning transmission dynamics modelling of COVID-19 using comomodels.

The COVID-19 epidemic continues to rage in many parts of the world. In the UK alone, an array of mathematical models have played a prominent role in guiding policymaking. Whilst considerable pedagogical material exists for understanding the basics of transmission dynamics modelling, there is a substantial gap between the relatively simple models used for exposition of the theory and those used in practice to model the transmission dynamics of COVID-19. Understanding these models requires considerable prerequisite knowledge and presents challenges to those new to the field of epidemiological modelling. In this paper, we introduce an open-source R package, comomodels, which can be used to understand the complexities of modelling the transmission dynamics of COVID-19 through a series of differential equation models. Alongside the base package, we describe a host of learning resources, including detailed tutorials and an interactive web-based interface allowing dynamic investigation of the model properties. We then use comomodels to illustrate three key lessons in the transmission of COVID-19 within R Markdown vignettes.

Rongchang and Xifeng capsules suppress pentylenetetrazole-induced seizures and change rest/wake behavior in zebrafish larvae.

OBJECTIVE: To evaluate the effects of Rongchang capsule and Xifeng capsule on pentylenetetrazole- induced epilepsy in zebrafish larvae and to explore the possible mechanisms behind their actions. METHODS: We utilized a trajectory tracking system to monitor seizures in zebrafish larva to confirm that certain concentrations of Rongchang capsule and Xifeng capsule produce antiepileptic effects. c-fos expression was assessed by quantitative reverse transcription-polymerase chain reaction to validate the efficacy of the capsules. Rest/wake behavior and correlation analysis predicted the targets of Rongchang capsule and Xifeng capsule. RESULTS: Larval movement times and total distances traveled by zebrafish larvae experiencing pentylenetetrazole (PTZ)-induced seizures were decreased by valproate treatment. Rongchang (500 µg/mL) and Xifeng (200 µg/mL) rescued the epileptic behaviors and down-regulated c-fos expression in the brains of larvae, which indicated antiepileptic effects. The rest/wake behavioral profiles showed that Rongchang and Xifeng differentially decreased rest time at night and increased larval locomotor activities during the day. Based on correlation between the actions of the two capsules and known compounds, we predicted that they might change rest/wake behaviors by affecting serotonin, GABAergic and histamine signaling pathways. CONCLUSION: The efficacy of Rongchang capsule and Xifeng capsule in alleviating epilepsy-like behaviors and molecular responses was confirmed. Our study provides insight into the capsules' effect on epilepsy.

Impact of low-dose chronic exposure to Bisphenol A (BPA) on adult male zebrafish adaption to the environmental complexity: Disturbing the color preference patterns and reliving the anxiety behavior.

The extensive usage of xenobiotic endocrine disrupting chemicals (XEDCs), such as Bisphenol A (BPA), has created obvious threat to aquatic ecosystems worldwide. Although a comprehensive understanding of the adverse effect of BPA on behaviors and physiology have been proven, the potential impact of low-dose BPA on altering the basic ability of aquatic organism in adapting to the surrounded complex environment still remains elusive. In this research, we report that treatment of adult male zebrafish with chronic (7 weeks) low-dose (0.22 nM-2.2 nM) BPA, altered the ability in adapting the complex environment by disturbing the natural color preference patterns. In addition, chronic 50 ng/L (0.22 nM) BPA exposure alleviated the anxiety behavior of male zebrafish confronted with the novel environment by enhancing the preference towards light in the light/dark preference test. This phenotype was associated with less expression of serotonin (5-TH) in the hypothalamus and the down-regulation of tyrosine hydroxylase (TH) in brain tissues. As such, our results show that low-dose BPA remnant in surface waters altered zebrafish behavior that are known to have ecological and evolutionary consequences. HIGHLIGHTS: Here we reported that the impact of chronic low-dose BPA exposure on the basic capability of zebrafish to adapt to the environmental complexity. Specifically, BPA at low concentration, under the environmental safety level and 3000-fold lower than the accepted human daily exposure, interfered with the ability to discriminate color and alleviate anxiety induced by the novel environment, which finally altered the capability of male zebrafish to adapt to the environmental complexity. These findings revealed the ecological effect of low-dose BPA and regular BPA concentration standard are not necessarily safe. The result also provided the consideration of retuning the hazard concentration level of BPA.