Influence of sucralose, acesulfame-k, and their mixture on brain's fish: A study of behavior, oxidative damage, and acetylcholinesterase activity in Daniorerio

Re-evaluation of acesulfame K (E 950) as food additive

The present opinion deals with the re-evaluation of acesulfame K (E 950) as a food additive. Acesulfame K (E 950) is the chemically manufactured compound 6-methyl-1,2,3-oxathiazin-4(3H)-one-2,2-dioxide potassium salt. It is authorised for use in the European Union (EU) in accordance with Regulation (EC) No 1333/2008. The assessment involved a comprehensive review of existing authorisations, evaluations and new scientific data. Acesulfame K (E 950) was found to be stable under various conditions; at pH lower than 3 with increasing temperatures, it is degraded to a certain amount. Based on the available data, no safety concerns arise for genotoxicity of acesulfame K (E 950) and its degradation products. For the potential impurities, based on in silico data, a concern for genotoxicity was identified for 5-chloro-acesulfame; a maximum limit of 0.1 mg/kg, or alternatively, a request for appropriate genotoxicity data was recommended. Based on the synthesis of systematically appraised evidence of human and animal studies, the Panel concluded that there are no new studies suitable for identification of a reference point (RP) on adverse effects. Consequently, the Panel established an acceptable daily intake (ADI) of 15 mg/kg body weight (bw) per day based on the highest dose tested without adverse effects in a chronic toxicity and carcinogenicity study in rats; a study considered of moderate risk of bias and one of two key studies from the previous evaluations by the Scientific Committee on Food (SCF) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA). This revised ADI replaces the ADI of 9 mg/kg bw per day established by the SCF. The Panel noted that the highest estimate of exposure to acesulfame K (E 950) was generally below the ADI in all population groups. The Panel recommended the European Commission to consider the revision of the EU specifications of acesulfame K (E 950).

Biosynthesis and metabolic engineering of natural sweeteners

Natural sweeteners have attracted widespread attention because they are eco-friendly, healthy, low in calories, and tasty. The demand for natural sweeteners is increasing together with the popularity of green, low-carbon, sustainable development. With the development of synthetic biology, microbial cell factories have emerged as an effective method to produce large amounts of natural sweeteners. This technology has significantly progressed in recent years. This review summarizes the pathways and the enzymes related to the biosynthesis of natural sweeteners, such as mogrosides, steviol glycosides, glycyrrhizin, glycyrrhetinic acid, phlorizin, trilobatin, erythritol, sorbitol, mannitol, thaumatin, monellin, and brazzein. Moreover, it focuses on the research about the microbial production of these natural sweeteners using synthetic biology methods, aiming to provide a reference for future research on the production of natural sweeteners.

Does maternal consumption of nutritive and non-nutritive sweeteners result in offspring hypertension?

The consumption of nutritive and non-nutritive sweeteners (NNS) has increased significantly in recent decades. The nutritional status of pregnant women plays a crucial role in determining the likelihood of their offspring developing hypertension in adulthood. While NNSs provide a sweet taste without adding to sugar intake, emerging evidence suggests that maternal consumption of not only nutritive sweeteners (such as fructose) but also NNS may lead to adverse outcomes in offspring, including hypertension. This review provides an overview of the latest research connecting maternal intake of sweeteners to the long-term risk of hypertension in offspring. We examine proposed mechanisms underlying the programming of offspring hypertension by sweeteners, encompassing oxidative stress, dysregulated nutrient sensing signals, abnormal renin-angiotensin system, transcriptome changes, and dysbiotic gut microbiota. Additionally, we outline preventive strategies that can help alleviate offspring hypertension programmed by maternal diets high in sweeteners. Recent advancements in understanding the mechanisms through which maternal consumption of nutritive and non-nutritive sweeteners contributes to offspring hypertension offer promise for addressing this widespread health concern at its developmental roots. Nonetheless, further research is needed to educate the public about the safety of sweetener consumption during pregnancy and lactation.

Identification of key genes related to growth of largemouth bass (Micropterus salmoides) based on comprehensive transcriptome analysis

Introduction

Largemouth bass is an economically important farmed freshwater fish species that has delicious meat, no intermuscular thorns, and rapid growth rates. However, the molecular regulatory mechanisms underlying the different growth and developmental stages of this fish have not been reported.

Methods

In this study, we performed histological and transcriptomic analyses on the brain and dorsal muscles of largemouth bass at different growth periods. The brain and muscle tissue were dehydrated, embedded, sliced and stained with hematoxylin-eosin. Images were captured under a microscope and acquired using a microphotographic system. Differential expression between groups was analyzed using DESeq2. GO functional analysis and KEGG pathway analysis were then performed for differentially expressed genes. RT-qPCR validates the reliability of transcriptome sequencing data.

Result

Smaller fish had more new muscle fiber numbers and wider intermuscular spaces compared to big specimens. Axons and nerve fibers were more pronounced in the telencephalons of big fish than in small fish. A total of 19,225 differentially expressed genes (DEGs) were detected in the muscle tissue, among which 7,724 were upregulated and 11,501 were downregulated, while a total of 5,373 DEGs were detected in the brain, among which 2,923 were upregulated and 2,450 were downregulated. GO and KEGG enrichment analyses indicated that nucleic acid binding, cytoskeletal motor activity, DNA binding, circadian rhythm, glycolysis/gluconeogenesis, and osteoclast differentiation were related to brain development while binding, cytoskeletal protein binding, biological processes, c-type lectin receptors, mitogen-activated protein kinase (MAPK) signaling pathways, and osteoclast differentiation were related to muscle growth. Stat3, pparg, akt1, mapk3, and mapk1 genes were mainly involved in the growth and development of largemouth bass.

Conclusion

These results provide novel perspectives for deepening our understanding of the mechanisms underlying the growth and development and performing genetic selection in largemouth bass.

A Novel Sulfatase for Acesulfame Degradation in Wastewater Treatment Plants as Evidenced from Shinella Strains

The artificial sweetener acesulfame is a persistent pollutant in wastewater worldwide. So far, only a few bacterial isolates were recently found to degrade acesulfame efficiently. In Bosea and Chelatococcus strains, a Mn2+-dependent metallo-β-lactamase-type sulfatase and an amidase signature family enzyme catalyze acesulfame hydrolysis via acetoacetamide-N-sulfonate to acetoacetate. Here, we describe a new acesulfame sulfatase in Shinella strains isolated from wastewater treatment plants in Germany. Their genomes do not encode the Mn2+-dependent sulfatase. Instead, a formylglycine-dependent sulfatase gene was found, together with the acetoacetamide-N-sulfonate amidase gene on a plasmid shared by all known acesulfame-degrading Shinella strains. Heterologous expression, proteomics, and size exclusion chromatography corroborated the physiological function of the Shinella sulfatase in acesulfame hydrolysis. Since both acesulfame sulfatase types are absent in other bacterial genomes or metagenome-assembled genomes, we surveyed 73 tera base pairs of wastewater-associated metagenome raw data sets. Bosea/Chelatococcus sulfatase gene signatures were regularly found from 2013, particularly in North America, Europe, and East Asia, whereas Shinella sulfatase gene signatures were first detected in 2020. Moreover, signatures for the Shinella sulfatase and amidase genes co-occur only in six data sets from China, Finland, and Mexico, suggesting that the Shinella genes were enriched or introduced quite recently in wastewater treatment facilities.

Reviewing the use of zebrafish for the detection of neurotoxicity induced by chemical mixtures through the analysis of behaviour

The knowledge and assessment of mixtures of chemical pollutants in the aquatic environment is a complex issue that is often challenging to address. In this review, we focused on the use of zebrafish (Danio rerio), a vertebrate widely used in biomedical research, as a model for detecting the effects of chemical mixtures with a focus on behaviour. Our aim was to summarize the current status of the ecotoxicological research in this sector. Specifically, we limited our research to the period between January 2012 and September 2023, including only those works aimed at detecting neurotoxicity through behavioural endpoints, utilizing zebrafish at one or more developmental stages, from egg to adult. Additionally, we gathered the findings for every group of chemicals involved and summarised data from all the works we included. At the end of the screening process 101 papers were considered eligible for inclusion. Results show a growing interest in zebrafish at all life stages for this kind of research in the last decade. Also, a wide variety of different assays, involving different senses, was used in the works we surveyed, with exposures ranging from acute to chronic. In conclusion, the results of this study show the versatility of zebrafish as a model for the detection of mixture toxicity although, for what concerns behavioural analysis, the lack of standardisation of methods and endpoints might still be limiting.

Ecotoxicological evaluation of chitosan biopolymer films particles in adult zebrafish (Danio rerio): A comparative study with polystyrene microplastics

To mitigate the environmental impact of microplastics (MPs), the scientific community has innovated sustainable and biodegradable polymers as viable alternatives to traditional plastics. Chitosan, the deacetylated form of chitin, stands as one of the most thoroughly investigated biopolymers and has garnered significant interest due to its versatile applications in both medical and cosmetic fields. Nevertheless, there is still a knowledge gap regarding the impact that chitosan biopolymer films (CBPF) may generate in aquatic organisms. In light of the foregoing, this study aimed to assess and compare the potential effects of CBPF on the gastrointestinal tract, gills, brain, and liver of Danio rerio against those induced by MPs. The findings revealed that both CBPF and MPs induced changes in the levels of oxidative stress biomarkers across all organs. However, it is essential to note that our star plots illustrate a tendency for CBPF to activate antioxidant enzymes and for MPs to produce oxidative damage. Regarding gene expression, our findings indicate that MPs led to an up-regulation in the expression of genes associated with apoptotic response (p53, casp3, cas9, bax, and bcl2) in all fish organs. Meanwhile, CBPF produced the same effect in genes related to antioxidant response (nrf1 and nrf2). Overall, our histological observations substantiated these effects, revealing the presence of plastic particles and tissue alterations in the gills and gastrointestinal tract of fish subjected to MPs. From these results, it can be concluded that CBPF does not represent a risk to fish after long exposure.

Assessing the impact of COVID-19 era drug combinations on hepatic functionality: A thorough investigation in adult Danio rerio

Current and thorough information on the ecotoxicological consequences of pharmaceuticals is accessible globally. However, there remains a substantial gap in knowledge concerning the potentially toxic effects of COVID-19 used drugs, individually and combined, on aquatic organisms. Given the factors above, our investigation assumes pivotal importance in elucidating whether or not paracetamol, dexamethasone, metformin, and their tertiary mixtures might prompt histological impairment, oxidative stress, and apoptosis in the liver of zebrafish. The findings indicated that all treatments, except paracetamol, augmented the antioxidant activity of superoxide dismutase (SOD) and catalase (CAD), along with elevating the levels of oxidative biomarkers such as lipid peroxidation (LPX), hydroperoxides (HPC), and protein carbonyl content (PCC). Paracetamol prompted a reduction in the activities SOD and CAT and exhibited the most pronounced toxic response when compared to the other treatments. The gene expression patterns paralleled those of oxidative stress, with all treatments demonstrating overexpression of bax, bcl2, and p53. The above suggested a probable apoptotic response in the liver of the fish. Nevertheless, our histological examinations revealed that none of the treatments induced an apoptotic or inflammatory response in the hepatocytes. Instead, the observed tissue alterations encompassed leukocyte infiltration, sinusoidal dilatation, pyknosis, fatty degeneration, diffuse congestion, and vacuolization. In summary, the hepatic toxicity elicited by COVID-19 drugs in zebrafish was less pronounced than anticipated. This attenuation could be attributed to metformin's antioxidant and hormetic effects.

The uses of zebrafish (Danio rerio) as an in vivo model for toxicological studies: A review based on bibliometrics

An in vivo model is necessary for toxicology. This review analyzed the uses of zebrafish (Danio rerio) in toxicology based on bibliometrics. Totally 56,816 publications about zebrafish from 2002 to 2023 were found in Web of Science Core Collection, with Toxicology as the top 6 among all disciplines. Accordingly, the bibliometric map reveals that "toxicity" has become a hot keyword. It further reveals that the most common exposure types include acute, chronic, and combined exposure. The toxicological effects include behavioral, intestinal, cardiovascular, hepatic, endocrine toxicity, neurotoxicity, immunotoxicity, genotoxicity, and reproductive and transgenerational toxicity. The mechanisms include oxidative stress, inflammation, autophagy, and dysbiosis of gut microbiota. The toxicants commonly evaluated by using zebrafish model include nanomaterials, arsenic, metals, bisphenol, and dioxin. Overall, zebrafish provide a unique and well-accepted model to investigate the toxicological effects and mechanisms. We also discussed the possible ways to address some of the limitations of zebrafish model, such as the combination of human organoids to avoid species differences.