Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials.

Due to the lack of new antimicrobial drug discovery in recent years and an ever-growing prevalence of multidrug-resistant "superbugs", there is a pressing need to explore alternative ways to combat pathogenic bacterial and fungal infections. Building upon our previous work in the field of medicinal phytochemistry, the present study is focused on designing, synthesizing, and testing the altered bioactivity of new variants of two original bioactive molecules found in the Argemone mexicana plant. Herein, we report upon 14 variants of berberine and four variants of chelerythrine that have been screened against a pool of 12 microorganisms (five Gram-positive and four Gram-negative bacteria, and three fungi). Additionally, the crystal structures of two berberine variants are described. Several berberine variants show enhanced antibacterial activity compared to the unaltered plant-derived molecule. We also report promising preliminary tumor cytotoxicity effects for a number of the berberine derivatives.

A mini review on the main challenges of implementing mechanical biological treatment plants for municipal solid waste in the Latin America region: Learning from the experiences of developed countries.

Most of the municipal solid waste (MSW) generated in the Latin America (LATAM) region is currently disposed of in landfills and dumpsites, which results in many negative environmental impacts. Mechanical biological treatment (MBT) is a strategy that combines the mechanical separation of recoverable materials with the biological stabilization of organic matter. MBT plants have proven to be a good alternative for the management of MSW and have been successfully implemented in developed countries for more than 30 years. However, the efficient introduction of these facilities in developing countries, such as those in the LATAM region, requires further feasibility studies. Therefore, this mini review seeks to offer significant insights into the main challenges that must be overcome to facilitate the implementation and operation of MBT plants, considering the unique technological, sociocultural, economic and political context of the LATAM region, through a comparison of the reported experiences of MBT plants in more developed countries with those in the LATAM region. The analysis herein indicates that key actions for the successful operation of MBT plants in the LATAM region include both the implementation of source separation as well as selective collection practices. Moreover, this work shows that other factors, like the establishment of valorization markets with safe working conditions for informal collectors, the development of intermunicipal cooperation schemes and the enforcement of strong regulatory frameworks for waste disposal specifications, are important contextual factors that have allowed the efficient operation of MBT plants in developed countries. Although the implementation of many of these practices will be challenging, such measures are necessary to increase the sustainability of MSW treatment practices in the LATAM region.

Characterizing a subtropical hypereutrophic lake: From physicochemical variables to shotgun metagenomic data.

Lake Cajititlán is a subtropical and endorheic lake, which is heavily impacted by nutrient pollution. Agricultural runoff and poorly treated wastewater have entered this reservoir at alarming rates during past rainy seasons, causing the cultural eutrophication of this body of water and resulting in several massive fish kill events. In this study, shotgun metagenomic sequencing was used to examine the taxonomic and functional structure of microbial communities in Lake Cajititlán during the rainy season. Several water quality features and their interactions with microbial communities were also assessed to identify the major factors affecting the water quality and biota, specifically fish species. According to current water quality regulations, most of the physicochemical variables analyzed (dissolved oxygen, pH, Secchi disk, NH4 +, NO3 -, blue-green algae, total phosphorus, and chlorophyll-a) were outside of the permissible limits. Planktothrix agardhii and Microcystis aeruginosa were the most abundant phytoplankton species, and the dominant bacterial genera were Pseudomonas, Streptomyces, and Flavobacterium, with Pseudomonas fluorescens, Stenotrophomonas maltophilia, and Aeromonas veronii representing the most abundant bacterial species. All of these microorganisms have been reported to be potentially harmful to fish, and the latter three (P. fluorescens, S. maltophilia, A. veronii) also contain genes associated with pathogenicity in fish mortality (fur, luxS, aer, act, aha, exu, lip, ser). Genetic evidence from the microbial communities analyzed herein reveals that anthropogenic sources of nutrients in the lake altered genes involved in nitrogen, phosphorus, sulfur, and carbon metabolism, mainly at the beginning of the rainy season. These findings suggest that abiotic factors influence the structure of the microbial communities, along with the major biogeochemical cycles of Lake Cajititlán, resulting in temporal variations and an excess of microorganisms that can thrive in high-nutrient and low-oxygen environments. After reviewing the literature, this appears to be the first study that focuses on characterizing the water quality of a subtropical hypereutrophic lake through associations between physicochemical variables and shotgun metagenomic data. In addition, there are few studies that have coupled the metabolism of aquatic ecosystems with nutrient cycles.

Transcriptional Profile of HCV Replicon Cells after Treatment with Acetylsalicylic Acid.

OBJECTIVE: It has been demonstrated in vitro that acetylsalicylic acid (ASA) treatment halves hepatitis C virus (HCV) expression in hepatocarcinoma cells. However, the signaling pathway that promotes this ASA-induced antiviral effect has not yet been identified. AIM: The aim of this work was to identify alterations in the transcriptional profile of Huh-7-HCV-subgenomic replicon cells with vs. without ASA treatment. This comparison sheds light onto the signaling pathways and molecular mechanisms involved in the antiviral effects of ASA. METHODS: Human hepatocellular carcinoma (Huh-7) cells that express non-structural HCV proteins (Huh-7-HCV-replicon cells) were exposed to 4 mM ASA for 0, 24, 48, and 72 hours. Total RNA was isolated, and cDNA was synthesized. Transcripts were then tagged with biotin and purified. Thereafter, they were fragmented and hybridized on HG-U133 Plus 2 Gene Expression chips. Hybridization signals were captured using a GeneChip 3000 7G Scanner and analyzed via Expression Console and dChip Software. RESULTS: When exposed to ASA, hepatocarcinoma cells with non-structural HCV proteins were found to differentially regulate genes with oxidative roles in the cell. The most upregulated genes were interleukin 8 (IL-8), cytochrome P450 (CYP450), and metallothioneins (MTs), while the most downregulated genes were ribonucleotide reductases (RRs). CONCLUSION: These results show that ASA modulates the expression of genes with antioxidant functions. This suggests that ASA induces a remodeling of the antioxidant microenvironment, which may in turn interfere with the replication of HCV.

Microalgae-based livestock wastewater treatment (MbWT) as a circular bioeconomy approach: Enhancement of biomass productivity, pollutant removal and high-value compound production.

The intensive livestock activities that are carried out worldwide to feed the growing human population have led to significant environmental problems, such as soil degradation, surface and groundwater pollution. Livestock wastewater (LW) contains high loads of organic matter, nitrogen (N) and phosphorus (P). These compounds can promote cultural eutrophication of water bodies and pose environmental and human hazards. Therefore, humanity faces an enormous challenge to adequately treat LW and avoid the overexploitation of natural resources. This can be accomplished through circular bioeconomy approaches, which aim to achieve sustainable production using biological resources, such as LW, as feedstock. Circular bioeconomy uses innovative processes to produce biomaterials and bioenergy, while lowering the consumption of virgin resources. Microalgae-based wastewater treatment (MbWT) has recently received special attention due to its low energy demand, the robust capacity of microalgae to grow under different environmental conditions and the possibility to recover and transform wastewater nutrients into highly valuable bioactive compounds. Some of the high-value products that may be obtained through MbWT are biomass and pigments for human food and animal feed, nutraceuticals, biofuels, polyunsaturated fatty acids, carotenoids, phycobiliproteins and fertilizers. This article reviews recent advances in MbWT of LW (including swine, cattle and poultry wastewater). Additionally, the most significant factors affecting nutrient removal and biomass productivity in MbWT are addressed, including: (1) microbiological aspects, such as the microalgae strain used for MbWT and the interactions between microbial populations; (2) physical parameters, such as temperature, light intensity and photoperiods; and (3) chemical parameters, such as the C/N ratio, pH and the presence of inhibitory compounds. Finally, different strategies to enhance nutrient removal and biomass productivity, such as acclimation, UV mutagenesis and multiple microalgae culture stages (including monocultures and multicultures) are discussed.

Rapid Changes in the Phytoplankton Community of a Subtropical, Shallow, Hypereutrophic Lake During the Rainy Season.

Lake Cajititlán is a small, shallow, subtropical lake located in an endorheic basin in western Mexico. It is characterized by a strong seasonality of climate with pronounced wet and dry seasons and has been classified as a hypereutrophic lake. This eutrophication was driven by improperly treated sewage discharges from four municipal wastewater treatment plants (WWTPs) and by excessive agricultural activities, including the overuse of fertilizers that reach the lake through surface runoff during the rainy season. This nutrient rich runoff has caused algal blooms, which have led to anoxic or hypoxic conditions, resulting in large-scale fish deaths that have occurred during or immediately after the rainy season. This study investigated the changes in the phytoplankton community in Lake Cajititlán during the rainy season and the association between these changes and the physicochemical water quality and environmental parameters measured in the lake's basin. Planktothrix and Cylindrospermopsis were the dominant genera of the cyanobacterial community, while the Chlorophyceae, Chrysophyceae, and Trebouxiophyceae classes dominated the microalgae community. However, the results showed a significant temporal shift in the phytoplankton communities in Lake Cajititlán induced by the rainy season. The findings of this study suggest that significant climatic variations cause high seasonal surface runoff and rapid changes in the water quality (Chlorophyll-a, DO, NH4 +, and NO3 -) and in variations in the composition of the phytoplankton community. Finally, an alternation between phosphorus and nitrogen limitation was observed in Lake Cajititlán during the rainy season, clearly correlating to the presence of Planktothrix when the lake was limited by phosphorus and to the presence of Cylindrospermopsis when the lake was limited by nitrogen. The evidence presented in this study supports the idea that the death of fish in Lake Cajititlán could be mainly caused by anoxia, caused by rapid changes in water quality during the rainy season. Based on our review of the literature, this is the first study on the phytoplankton community in a subtropical lake during the rainy season using high throughput 16S rRNA and 18S rRNA amplicon sequencing.

The Dehydratase ADT3 Affects ROS Homeostasis and Cotyledon Development.

During the transition from seed to seedling, emerging embryos strategically balance available resources between building up defenses against environmental threats and initiating the developmental program that promotes the switch to autotrophy. We present evidence of a critical role for the phenylalanine (Phe) biosynthetic activity of AROGENATE DEHYDRATASE3 (ADT3) in coordinating reactive oxygen species (ROS) homeostasis and cotyledon development in etiolated Arabidopsis (Arabidopsis thaliana) seedlings. We show that ADT3 is expressed in the cotyledon and shoot apical meristem, mainly in the cytosol, and that the epidermis of adt3 cotyledons contains higher levels of ROS Genome-wide proteomics of the adt3 mutant revealed a general down-regulation of plastidic proteins and ROS-scavenging enzymes, corroborating the hypothesis that the ADT3 supply of Phe is required to control ROS concentration and distribution to protect cellular components. In addition, loss of ADT3 disrupts cotyledon epidermal patterning by affecting the number and expansion of pavement cells and stomata cell fate specification; we also observed severe alterations in mesophyll cells, which lack oil bodies and normal plastids. Interestingly, up-regulation of the pathway leading to cuticle production is accompanied by an abnormal cuticle structure and/or deposition in the adt3 mutant. Such impairment results in an increase in cell permeability and provides a link to understand the cell defects in the adt3 cotyledon epidermis. We suggest an additional role of Phe in supplying nutrients to the young seedling.

Pirin1 (PRN1) is a multifunctional protein that regulates quercetin, and impacts specific light and UV responses in the seed-to-seedling transition of Arabidopsis thaliana.

Pirins are cupin-fold proteins, implicated in apoptosis and cellular stress in eukaryotic organisms. Pirin1 (PRN1) plays a role in seed germination and transcription of a light- and ABA-regulated gene under specific conditions in the model plant system Arabidopsis thaliana. Herein, we describe that PRN1 possesses previously unreported functions that can profoundly affect early growth, development, and stress responses. In vitro-translated PRN1 possesses quercetinase activity. When PRN1 was incubated with G-protein-α subunit (GPA1) in the inactive conformation (GDP-bound), quercetinase activity was observed. Quercetinase activity was not observed when PRN1 was incubated with GPA1 in the active form (GTP-bound). Dark-grown prn1 mutant seedlings produced more quercetin after UV (317 nm) induction, compared to levels observed in wild type (WT) seedlings. prn1 mutant seedlings survived a dose of high-energy UV (254 nm) radiation that killed WT seedlings. prn1 mutant seedlings grown for 3 days in continuous white light display disoriented hypocotyl growth compared to WT, but hypocotyls of dark-grown prn1 seedlings appeared like WT. prn1 mutant seedlings transformed with GFP constructs containing the native PRN1 promoter and full ORF (PRN1::PRN1-GFP) were restored to WT responses, in that they did not survive UV (254 nm), and there was no significant hypocotyl disorientation in response to white light. prn1 mutants transformed with PRN1::PRN1-GFP were observed by confocal microscopy, where expression in the cotyledon epidermis was largely localized to the nucleus, adjacent to the nucleus, and diffuse and punctate expression occurred within some cells. WT seedlings transformed with the 35S::PRN1-GFP construct exhibited widespread expression in the epidermis of the cotyledon, also with localization in the nucleus. PRN1 may play a critical role in cellular quercetin levels and influence light- or hormonal-directed early development.

G protein signaling in UV protection: methods for understanding the signals in young etiolated seedlings.

A seed is competent to respond to light soon after imbibition. A new developmental program begins in or on the ground where the young seedling may be exposed to heat, cold, drought, flooding (anoxia), salts, varying levels of visible light, and the topic of this paper, ultraviolet radiation. Herein what is described is a method for growing and maintaining seedlings, then methods of UV irradiation in order to measure discrete effects of UV wavelengths in signal transduction, very early in seedling development. The physiological response to an abiotic signal is partly dependent on the developmental state of the plant. Dark-grown seedlings of plant species possess young leaves or leaf primordia in a "suspended" state of development whereby exposure to sunlight, visible and UV, is required to initiate the leaf developmental program, including development of etioplasts or proplastids into fully functioning chloroplasts. In order for us to understand the initial and persisting effects of UV in seedlings, we "delay" light-induced development by carrying out all experiments in complete darkness between days 0 (seed) and day 7 (Arabidopsis). In this case, the UV regulation of a simple signaling pathway in Arabidopsis, G protein signaling in UV protection and acclimation early in development, is investigated with the use of several mutants and easily score-able phenotypes.