Obesity is a condition that has been linked to male infertility. The current hypothesis regarding the cause of infertility is that sperm are highly sensitive to reactive oxygen species (ROS) during spermatogenesis in the testes and transit through the epididymides, so the increase in ROS brought on by obesity could cause oxidative stress. The aim of this study was to evaluate whether the activity of the enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) is capable of counteracting oxidative stress in sperm. The male Wistar rat was used as an overweight and obesity model, and analysis of fertility in these groups was carried out including the control group. Serum testosterone levels were determined, and the scrotal fat, testes, and epididymides were extracted. The epididymides were separated ini0 3 principal parts (caput, corpus, and cauda) before evaluating sperm viability, sperm morphology, damage to desoxyribonucleic acid of the sperm, and ROS production. The protein content and specific activity of the three enzymes mentioned above were evaluated. Results showed a gain in body weight and scrotal fat in the overweight and obese groups with decreased parameters for serum testosterone levels and sperm viability and morphology. Fertility was not greatly affected and no DNA integrity damage was found, although ROS in the epididymal sperm increased markedly and Raman spectroscopy showed a disulfide bridge collapse associated with DNA. The specific activities of CAT and GPX increased in the overweight and obesity groups, but those of SOD did not change. The amounts of proteins in the testes and epididymides decreased. These findings confirm that overweight and obesity decrease concentrations of free testosterone and seem to decrease protein content, causing poor sperm quality. Implications. An increase in scrotal fat in these conditions fosters an increase of ROS, but the increase of GPX and CAT activity seems to avoid oxidative stress increase in the sperm without damaging your DNA.

Pseudomonas fluorescens is a bacterium that has been identified as a significant pathogen in fish from the aquaculture industry. However, the clinical signs and changes caused by the disease have not been studied well yet. This study aimed to determine the survival, morphological, and histopathological changes in zebrafish (Danio rerio) in an experiment involving 180 fish (0.250 ± 0.05 g). The organisms were inoculated intraperitoneally at four bacterial concentrations 1.5 × 10⁶, 1.5 × 10⁷, 1.5 × 10⁸, and 1.5 × 10⁹ CFU mL⁻¹ with respective control groups. Results showed that cumulative mortality at 96 h post infection (hpi) was 0% (1.5 × 10⁶ CFU mL⁻¹), 0% (1.5 × 10⁷ CFU mL⁻¹), 6.66% (1.5 × 10⁸ CFU mL⁻¹), and 33.33% (1.5 × 10⁹ CFU mL⁻¹). The survival curves were not statistically different (p = 1.000). Corresponding to differences between clinical signs and concentrations for 24 hpi (p = 0.7576) there were no significant differences, for 48 hpi statistical differences were obtained (p = 0.0008), while for 72 hpi (p = 0.8922) and 96 hpi (p = 0.333) they were not observed. The predominant clinical signs were anorexia, lethargy, erratic swimming, and peritoneal haemorrhage. The acute septicemic clinical form was determined. Histological analyses showed that the gills, liver, and spleen were infected and had severe pathological alterations. These findings indicate that the zebrafish is susceptible to P. fluorescens infection.

Chirostoma humboldtianum is an endemic atherinopsid from Mexico that has been of high socio-cultural and economic importance since pre-Hispanic times. It was the first ictic species from Mexico described for science, and it is considered the basal species that gave rise to a nominal group known as white fish or silversides. The aim of this research was to analyze semen quality in relation to breeding fish size and its effect on sperm cryopreservation during an annual cycle. Sexually mature males were collected from January to December 2023, in San Felix dam, Tiacaque, Mexico State, Mexico. The water temperature was measured, and the photoperiod was obtained from the Instituto Nacional de Geografía y Estadística (INEGI). Males were classified into two groups of total length (TL) after analyzing the variation in TL through a size histogram: (G1) 9–13 cm and (G2) longer than 13 cm. Semen volume (µL), sperm concentration (cells µL⁻¹), and motility percentage (%) were determined in all individuals of each group. Likewise, eight straws were cryopreserved per month per group, each one with 10 µL of semen from a mixture of three randomly selected individuals and cryopreserved at −196 °C for 72 h. The post-thawing motility percentage was subsequently verified. Males produce semen continuously all year round, with two periods of higher volume, March and June–August, defining two reproductive periods. The beginning of the first one coincides with the increase in water temperature, from 13 ± 2 to 18 °C. Males with a length more than 13 cm had a higher semen production compared to smaller males (17.33 ± 7.34 and 12.52 ± 4.41 µL, respectively, p < 0.05). The largest semen volumes were registered in March and from June to August in both groups. However, G2 males presented with a larger semen volume. Both groups had a marked decrease in a similar manner in April–May and September to January (p < 0.05). Sperm concentration was similar throughout the year in both groups (p > 0.05) (G1 = 1.35 ± 0.36 × 10⁶ µL⁻¹) (G2 = 1.31 ± 0.35 × 10⁶ µL⁻¹). In addition, fresh sperm motility was high in both groups (G1 = 96 ± 3%, G2 = 97 ± 4%) (p > 0.05). The highest sperm concentrations were observed in March to July, through to October for both groups (p > 0.05), while post-thaw sperm motility decreased by about 50% (G1 = 45 ± 4%) (G2 = 46 ± 6%) during the annual cycle (p > 0.05). The largest post-thaw motility was observed in March and from July to September in G1 and in March and from June to October in G2. Analysis of semen quality throughout the annual cycle reveals aspects of the reproductive biology of C. humboldtianum, including two reproductive peaks and continuous semen production.

La reproducción en peces está regulada por factores ambientales, sociales y químicos, aunado a cambios constantes en la temperatura del agua, variables que tienen una gran importancia en la producción y liberación de hormonas y feromonas reproductivas. Los peces se han adaptado a la época más favorable de su estrategia reproductiva. Pero, ¿cómo perciben los factores ambientales los peces? ¿Cómo se sincronizan los machos y las hembras para el desove simultáneo? Este artículo tiene como propósito comprender cómo los peces captan los factores ambientales y cómo los traducen para poder reproducirse, información importante para optimizar la reproducción y conservación in situ, en centros acuícolas o de investigación.