Carina Shianya Alvarez-Villagomez

Background: Artificial non-nutritive sweeteners (NNSs), such as sucralose, have been associated with gut microbiota (GM) alterations. However, the impact of rebaudioside A (reb A), a natural NNS, on GM has received limited scrutiny. Objective: The objective of this study was to examine the response of GM composition to sucralose and reb A in rats under two dietary conditions. Methods: Male Wistar rats (150–200 g) fed with a normal diet (ND) or a high-fat diet (HFD) were randomly assigned to receive sucralose (SCL), reb A (REB), glucose (GLU, control), or sucrose (SUC). The NNS interventions were administered in water at doses equivalent to the acceptable daily intake (ADI). After eight weeks, the GM composition in fecal samples was analyzed through 16S ribosomal RNA gene sequencing. Results: The NNSs did not modify the diversity, structure, phylum-level composition, or Firmicutes/Bacteroidetes (F/B) ratio of the GM in rats under ND or HFD. However, REB with HFD decreased Bacilli and increased Faecalibacterium abundance at the class level. SCL and REB in rats receiving ND reduced the genera Romboutsia and Lactobacillus. Conclusions: Our study suggests that when sucralose or reb A is consumed at recommended doses, there is no alteration in the diversity or the composition of the GM at the phylum level. The clinical relevance of these findings lies in the potential modifications of the GM at specific taxonomic levels by the consumption of these NNSs. Further research involving humans and including a broader range of microbial analyses is warranted.

The tropical gar (Atractosteus tropicus), a freshwater species mostly found in swamps, has been used for human consumption for several generations. In this study, the expression of interferon-gamma (ifn-γ) and domain nucleotide-binding oligomerization (nod1) involved in the immune system was evaluated in different tissues such as the brain, heart, spleen, liver, pancreas, kidney, intestine, and gonad in wild and captive adult organisms and during early ontogeny. Specific quantitative polymerase chain reaction (qPCR) primers were used to compare the expression between tissues and during larviculture, starting with embryos (0 days after hatching, [DAH]) and at 5, 10, 15, 20, 25, and 30 DAH. The intestine, pancreas, and liver showed maximum ifn-γ and nod1 expression. Additionally, the expression of genes ifn-γ and nod1 was detected in embryos (0 DAH), decreasing between 5 and 10, then increasing at 25 and 30 DAH. Based on these results, it can be concluded that genes encoding ifn-γ and nod1 are expressed differentially across tissues of tropical gar adults and are regulated during larval development.

The tropical gar (Atractosteus tropicus) is a primitive freshwater fish of significant commercial importance in southeastern Mexico. However, its population is in danger due to habitat loss and overexploitation. Cultivation emerges as a viable reproductive management strategy; yet further studies are crucial to understanding molecular markers guiding reproductive management, differentiation, and sexual maturation in this species. We analyzed the expression of five sex-related genes (foxl2, sox9, cyp17a1, dmrt1, and cyp19a1) in the brain, liver, and gonads of adult A. tropicus (four females and five males). Methodologically, we collected samples and conducted RNA extraction, cDNA synthesis, and gene expression analysis using qPCR. The gonadal histology provided morphological context that reveals that the differential expression of genes establishes differences between sexes. The sexual phenotype of females is observed with the high expression of dmrt1, while in males, there is a reduction in the expression of dmrt1 and high levels of sox9, foxl2, and cyp17a1. Our findings establish dmrt1 and cyp19a1 as potential sex biomarkers and provide a molecular basis for developing sexing protocols in A. tropicus.

The bay snook (Petenia splendida) belongs to the family Cichlidae, distributed in the southeastern region of Mexico and Central America, and it is a very important cichlid at a commercial level. Despite their potential for aquaculture, little information exists on their metabolic pathways related to physiology and nutrition. This study focuses on the expression of the fatty acid desaturases (fads2) and elongases (elovl4b and elovl5) genes in embryos 0 days post-hatching (dph) and larvae of 5, 10, 15, 20, 25, and 30 dph. Additionally, the differential expression of these genes was analyzed in the liver, intestine, kidney, muscle, heart, testes, gills, stomach, pancreas, brain, and adipose tissue in adult fish. Our study utilized specific qPCR primers designed for fads2, elovl4b, and elovl5 to detect the expression of these genes. We found the highest expression were observed in larvae at 20 dph and adults, predominantly in the liver and intestine of the three genes tested. Importantly, our results showed that the desaturase and elongase genes are differentially expressed in the tissues of adults of P. splendida, and their expression fluctuates during larval development.

Including probiotic yeasts, such as Debaryomyces hansenii, in fish diets improves aquaculture production and fish health. Some fish-isolated yeasts, like Candida tropicalis, produce antimicrobial metabolites. However, there have been no reports on their in vivo effects. We evaluated the effects of dietary administration of both yeasts on growth, survival, digestive enzyme activity, expression of intestinal barrier genes, and intestinal microbiota composition in Atractosteus tropicus juveniles. We administered diets with three concentrations of C. tropicalis (104, 106, and 108 CFU g-1), three with D. hansenii (103, 105, and 107 CFU g-1), and a control diet without yeast for 45 days. We also evaluated the antagonistic capacity of both yeasts against fish pathogens in vitro. Results showed that lower doses of C. tropicalis (104 CFU g-1) and D. hansenii (103 CFU g-1) improved growth, survival, and lipase activity. However, C. tropicalis compromised intestinal barrier integrity by reducing zo-1 expression and increasing il-8 expression while altering the microbiota to favor Desulfovibrionaceae. Conversely, D. hansenii enhanced intestinal barrier integrity by increasing the expression of muc-2, zo-1, and il-10 genes and decreasing il-8 expression without altering the microbiota, where Mycoplasma predominated. Both yeasts showed antagonistic activity against pathogens. In conclusion, the dietary inclusion of C. tropicalis did not favor the intestinal health of the fish. Conversely, D. hansenii at a concentration of 103 CFU g-1 is recommended to improve the growth, digestive function, and health of A. tropicus juveniles.

Sucralose stands as the most common non-nutritive sweetener; however, its metabolic effects have sparked significant controversy over the years. We aim to examine the effects of sucralose daily intake on glycemia, subjective appetite, and gut microbiota (GM) changes in subjects with overweight or obesity. In this randomized, crossover, and controlled trial, 23 participants with a body mass index between 25 kg/m² and 39.9 kg/m² will be assigned to one of two interventions to receive either sucralose (2 mg/kg/day equivalent to 40% of the acceptable daily intake) or glucose (control) for 4 weeks, each phase separated by a 4-week washout period. The glycemic response will be determined during a meal tolerance test, subjective appetite will be evaluated using a visual analog scale, and GM changes will be analyzed by next-generation sequencing of the bacterial rRNA 16S gene from fecal samples. All measures will be performed before and after intervention periods. We hypothesize that sucralose supplementation induces changes in glycemic response, subjective appetite, and gut microbiota in overweight and obese participants. This protocol was approved by the Ethics Committee of the UJAT (No. 0721) and was registered in the Australian New Zealand Clinical Trials Registry (ACTRN12621001531808).

Probiotics in aquaculture hold promise for enhancing fish health and growth. Due to their increased specificity and affinity for their host, indigenous probiotics may offer isolated and potentially amplified benefits. This study investigated the effects of Lactococcus lactis PH3-05, previously isolated from adults of tropical gar (Atractosteus tropicus), on the growth, survival, digestive enzyme activity, intestinal morphology, expression of barrier and immune genes, and intestinal microbiota composition in the larvae of tropical gar. Larvae were fed with live L. lactis PH3-05 concentrations of 10⁴, 10⁶, and 10⁸ CFU/g for 15 days alongside a control diet without probiotics. Higher concentrations of L. lactis PH3-05 (10⁶ and 10⁸ CFU/g) positively influenced larval growth, increasing hepatocyte area and enterocyte height. The 10⁶ CFU/g dose significantly enhanced survival (46%) and digestive enzyme activity. Notably, the 10⁸ CFU/g dose stimulated increased expression of muc-2 and il-10 genes, suggesting enhanced mucosal barrier function and anti-inflammatory response. Although L. lactis PH3-05 did not significantly change the diversity, structure, or Phylum level composition of intestinal microbiota, which was constituted by Proteobacteria, Bacteroidota, Chloroflexi, and Firmicutes, an increase in Lactobacillus abundance was observed in fish fed with 10⁶ CFU/g, suggesting enhanced probiotic colonization. These results demonstrate that administering L. lactis PH3-05 at 10⁶ CFU/g promotes growth, survival, and digestive health in A. tropicus larvae, establishing it as a promising indigenous probiotic candidate for aquaculture applications.

The intracohort cannibalism present in tropical gar larvae (A. tropicus) generates great problems in its culture, as in other fish species around the world. The addition of tryptophan (Trp) (10, 20, and 30 g/kg) and a control diet (CD) without Trp were evaluated in A. tropicus larvae regarding growth, survival, cannibalism, behavior, digestive enzymatic activity, and genes related to aggressiveness and/or cannibalism in two stages: 0–13 days after hatching (DAH); and only cannibals (14–24 DAH). In the first stage, no differences were observed in growth parameters; cannibalism was lower with the use of Trp, with the lowest percentage being the 10 g/kg Trp treatment (56.75 ± 2.47%) compared to CD (64.75 ± 1.76%). In the second stage, survival was greater in 10 g/kg Trp (75.00 ± 7.07%) than in CD (23.33 ± 5.77%). Thus, cannibalism was lower with 10 g/kg Trp (20.0 ± 10.0%) compared to CD (76.66 ± 5.77%). Cannibal larvae fed with 10 g/kg Trp had a greater enzymatic activity in acid and alkaline proteases and leucine aminopeptidase, as well as the overexpression of avpi1, crh, and htr1a and the subexpression of tph1, th, sstr1, and hdc (p < 0.05). No aggressive behaviors were recorded in the larvae fed with the 10 g/kg Trp treatment, unlike those fed with CD. The use of 10 g/kg Trp improves survival and reduces cannibalism in A. tropicus larvae.