Biochemical Analysis Leads to Improved Orthogonal Bioluminescent Tools.

Engineered luciferase-luciferin pairs have expanded the number of cellular targets that can be visualized in tandem. While light production relies on selective processing of synthetic luciferins by mutant luciferases, little is known about the origin of selectivity. The development of new and improved pairs requires a better understanding of the structure-function relationship of bioluminescent probes. In this work, we report a biochemical approach to assessing and optimizing two popular bioluminescent pairs: Cashew/d-luc and Pecan/4'-BrLuc. Single mutants derived from Cashew and Pecan revealed key residues for selectivity and thermal stability. Stability was further improved through a rational addition of beneficial residues. In addition to providing increased stability, the known stabilizing mutations surprisingly also improved selectivity. The resultant improved pair of luciferases are >100-fold selective for their respective substrates and highly thermally stable. Collectively, this work highlights the importance of mechanistic insight for improving bioluminescent pairs and provides significantly improved Cashew and Pecan enzymes which should be immediately suitable for multicomponent imaging applications.

Application of exogenous melatonin in vitro and in planta: a review of its effects and mechanisms of action.

Melatonin is a natural indolamine that regulates many physiological functions in plants. The most prominent role of melatonin in plants has been its ability to work as an anti-stressor agent. Exogenous melatonin can prevent cell death and promote cell proliferation through its antioxidant properties, enhancement of polyamine biosynthesis, and the ability to shift cell metabolism in case of stressors like sugar starvation. Melatonin scavenges reactive oxygen species and thus preventing damage to cell membranes and other organelles. Its application in different plant culture systems reveals its important physiological and biochemical roles during the growth and development of these cultures. It has been observed that the exogenous melatonin protects callus culture, reduces cold-induced apoptosis in cell suspension, and stimulates adventitious and lateral roots formation. This review presents the physiological and biochemical effects of exogenous melatonin on in vitro culture systems, including its impact on biomass accumulation, growth, and development of plants.

Red light enhances the antibacterial properties, biofabrication, and stability of Fagonia indica callus-based silver nanoparticles.

Plant-based nanoparticles can be tuned through the frequency of light for efficient synthesis, structural properties, and antibacterial applications. This research assessed the effect of material type (callus and whole-plant extract) and the interaction with a specific range of light wavelength on AgNP synthesis. All types of AgNPs were characterized by their size, shape, associated functional groups, and surface charge. Interestingly, the size of red light and callus-based AgNPs (RC-AgNPs) was smaller (6.32 nm) compared to 14.59 nm for Ultraviolet light and callus-based AgNPs (UV-C-AgNPs). Zeta potential analysis showed that RC-AgNPs had higher stability (-29.2 mV) compared to UV-C-AgNPs (-16.7 mV). Similarly, red light-based AgNPs had higher Oxidation reduction potential in both whole-plant-based and callus-based AgNPs, indicating a more oxidizing nature compared to those synthesized under UV light. This was confirmed by the lower total phenolic and flavonoid content associated with them and their lower antioxidant activity. The higher antibacterial activities and lower minimum inhibitory concentrations of red light-based AgNPs against highly resistant pathogenic bacteria demonstrated the role of red light in enhancing antibacterial activity. These results indicate that AgNPs synthesized in red light and callus extract are more active compared to those synthesized under other wavelengths and/or in whole-plant extracts.

On Patterns of Neuropsychiatric Symptoms in Patients With COVID-19: A Systematic Review of Case Reports.

Coronavirus disease 2019 (COVID-19) has various neuropsychiatric manifestations, including psychotic, mood, anxiety disorders, trauma-related disorders, and cognitive disorders, such as delirium. Although the psychosocial effects of the COVID-19 pandemic contribute to an increase in psychiatric comorbidities, the COVID-19 virus is also an independent risk factor. Previous studies have revealed that the virus can invade the neural tissue, which causes an imbalance of neurotransmitters that cause neuropsychiatric symptoms. The aim of this article is to conduct a systematic review to determine the patterns of neuropsychiatric manifestations of COVID-19, discussing the frequency and its impact on pre-existing psychiatric disorders. Thirty-nine case reports were collected and analyzed for a systematic review. They were full-text, peer-reviewed journal publications from November 2020 to February 2021. Fifty-three patients were included in our study. The most frequent symptom was abnormal/bizarre behavior (50.9%), followed by agitation/aggression (49.1%), and the third most common was altered mental status and delirium (47.2%). Only 48% of our patients had a pre-existing psychiatric disorder, including three not formally diagnosed but displayed psychiatric symptoms prior to the COVID-19 infection. Findings suggest a positive correlation of new-onset psychiatric symptoms with the SARS-CoV-2 virus. However, the exact pathophysiology of the virus itself causing neuropsychiatric manifestations needs to be investigated further.