Measurement of catalase activity in tissue extracts☆

Phosphorus (P) is considered to be one of the most limiting elements in terrestrial ecosystems, especially in the subtropical forests in China. However, little is known about how rhizosphere soil bacterial communities and functions, especially at the level of functional genes abundance, respond to P inputs. Herein we conducted a P addition experiment and treatments included 80 g m⁻² yr⁻¹ (P1), 160 g m⁻² yr⁻¹ (P2), 240 g P m⁻² yr⁻¹ (P3), 320 g P m⁻² yr⁻¹ (P4) and the control without any fertilizer application (CK) in the Phoebe bournei young plantations. This study used the quantitative microbial element cycling (QMEC) smart chip technology and 16S rRNA gene sequencing to investigate changes in the relative abundance of C-, N-, and P-cycle genes and rhizosphere soil bacterial community that received various inputs of P nutrients. Soil bacterial diversity showed a progressively decreased trend with increasing of P fertilizer, accompanied by significant differences in bacterial community structure between CK and P4 treatment. The relative abundance of N- and P-cycle genes were increased by P addition, and the highest relative abundance was observed in P3 treatment among the five P addition treatments. The relative abundance of C-cycle genes was significantly enhanced by P4 treatment, promoting C fixation, degradation, and methane metabolism. Random forest model indicated that invertase activity was the most important predictor for the relative abundance of C-, N-, and P-cycle genes. Partial least squares path modeling analysis revealed that the predominant effect of P fertilizer in driving the relative abundance of functional genes was maintained when accounting for multiple abiotic factors (total P, available P, available potassium, soil organic carbon and soil pH) drivers and there was a strong relationship between the relative abundance of functional genes and catalase, invertase and urease activities. Overall, our findings confirm that high P addition significantly altered rhizosphere soil bacterial community composition in the Phoebe bournei young plantations, and significantly enhanced the relative abundance of C-, N- and P-cycle genes. These results suggest that sufficient P fertilizer benefits to improve the nutrients cycle processes mediating by soil bacteria in Phoebe bournei young plantations.

Chlorination is the common antifouling method in desalination and power plant water intake structures to control microbial and macrofouling growth. In this study, the impacts of chlorine dioxide on toxicity, metabolic activity and biochemical markers like glutathione S-transferase and catalase enzyme activity were tested using four zooplankton species (Centropages sp., Acartia sp., Oncaea sp., and Calanus sp.) collected from the Red Sea. The zooplankton species were treated with different concentrations (0.02, 0.05, 0.1, 0.2, and 0.5 mg L⁻¹) of chlorine dioxide. Further, chlorite, the main decomposition product of chlorine dioxide, was used for molecular docking studies against glutathione S-transferase and catalase enzymes. The results indicated the LC₅₀ range of 0.552–1.643 mg L⁻¹ for the studied zooplankton species. The respiration rate of the zooplankton increased due to the chlorine dioxide treatment with a maximum of 0.562 μg O₂ copepod h⁻¹ in Acartia. The glutathione S-transferase and catalase enzyme activities showed elevated values in zooplankton treated with chlorine dioxide. Molecular docking of chlorite with enzymes involved in antioxidant defense activity, such as glutathione S-transferase and catalase enzyme showed weak interactions. Overall, this study yielded significant insights for understanding the effects of chlorine dioxide on the survival, metabolism, and biochemical composition of marine zooplankton.

While the toxicity of nano-microplastics and polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms is well-studied, their joint impact on microalgae is less explored. This study focused on single and combined effects of PS-NPs (30 nm; concentrations: 2, 5, 10, and 25 mg/L) and two PAHs (chrysene and fluoranthene at 10, 100 µg/L) for 96 h on the accumulation, growth, photosynthetic parameters, and oxidative stress in the Chlamydomonas reinhardtii. The findings revealed that exposure to increasing concentrations of PS-NPs significantly reduced the growth inhibition ratio and chlorophyll-a content after 96 h. Both PAHs (100 µg/L) + PS-NPs (25 mg/L), significantly reduced the growth inhibition ratio and chlorophyll-a levels. Individual and combined exposures of PS-NPs and PAHs can prompt antioxidant responses like SOD, GPx, and GST, as well as an unaffected level of non-enzymatic antioxidant GSH and diminished CAT activity. Furthermore, both PAHs + PS-NPs triggered ROS levels, resulting in cell membrane damage. However, the reduced oxidative effect of LPO of combined exposures can be attributed to the activation of antioxidant defenses. In addition, the microscopic visualization data shows that PS-NPs adhered to the surface of microalgae. Also, PS-NPs reduced the adsorption of PAHs on the surface of C. reinhardtii. Altogether, this study implied that the influence of coexistent PS-NPs should be considered in the environmental risk assessment of PAHs in aquatic environments.

Land snails occupy a variety of habitats, with differing temperature and humidity regimes and exhibit a wide span of adaptations, to withstand abiotic condition changes. The present work's aim was to examine the correlation of habitat's thermal adversity in different Mediterranean type habitats with the land snail's antioxidant and heat shock responses. For this purpose, snails of different species from populations along a north–south axis from the islands and mainland of Greece were exposed to elevated temperature and antioxidant enzyme activities, and Hsp70 and Hsp90 levels were determined in their tissues. The ATP, ADP, and AMP levels and the adenylate energy charge (AEC) were also determined. The comparison of protein levels and enzymatic activities across time intervals revealed significant differences for all factors examined. While the gradation pattern over time for a given factor was similar in all populations the absolute values over time differed. Catalase activity and the Hsp90 protein levels had the higher contribution in separating the different species and populations, followed by the activity of glutathione reductase and Hsp70 protein levels which contributed to a lesser degree. In general, populations from the southern part of their distribution in Greece tend to display a faster increase than northern populations in induction levels of all factors examined. Our data seem to be in line with the concept of preparation for oxidative stress (POS) while the changes in the AEC indicate an early preparation to cover the energy demand for the induction and synthesis of antioxidant enzymes and Hsps.

Traditional methods for determining superoxide dismutase (SOD) content and catalase (CAT) activity rely on measuring the absorbance of individual tissue (biological) samples using a cuvette and spectrophotometer, rather than cell cultures. Although there are kits available for SOD and CAT assays, these allow for high-throughput analysis of samples and might be too expensive for research laboratories in countries from the Global South, such as South Africa. This paper describes a simple and cost-effective method to determine SOD content and CAT activity in mammalian cell cultures following exposure to environmental chemical mixtures by measuring absorbance in 96-well microplates. Moreover, the equipment used for this method is considered standard for cell culture laboratories, while the reagents and consumables are easily obtainable.

• •

  Antioxidant enzyme levels can be measured in vitro in cell cultures.

• •

  The supernatant obtained can be used to determine protein concentration, SOD content, and CAT activity.

• •

  This method is simple and affordable, allowing for the analysis of multiple samples (up to 32 samples per microplate).

Colorectal cancer is the third most prevalent malignant neoplasm in the world and remains a leading cause of death, particularly in western nations. This study aimed to evaluate the apoptotic and antioxidant activities of Spondias mombin stem bark extracts in dimethylhydrazine (DMH) induced colon cancer in Wistar rats as well as to investigate the binding affinities of epicatechin, kaempferol and Lunamarin against p53 and caspase 3 proteins.

A total of thirty-five (35) male Wistar rats were used for this experiment. They were grouped into five groups: Group 1 (normal control), Group 2 (DMH only- negative control), Group 3 (DMH + Xeloda - Standard Drug), Group 4 (DMH + 500 mg/kg bwt crude hydroethanol extracts), Group 5 (DMH + 500 mg bwt crude ethanol extracts.

The results showed high expression of proapoptotic genes which are Caspase-3 genes, B cell lymphoma 2 genes, and p53 genes and there was down regulation of antiapoptotic genes - Bcl like protein 4 genes. Also, the extracts of S. mombin stem bark attenuate the decreased antioxidant status (CAT, SOD and GSH) of DMN-induced colorectal cancer in rats and a significant decrease in the malondialdehyde levels. Molecular docking of the compounds (epicatechin, kaempferol and Lunamarin) against caspase 3 proteins possesses strong binding affinities with binding energies of -7.1, -7.0 and -7.5 kcal/mol respectively. However, kaempferol had similar binding energy(-7.0 kcal/mol) when docked against p53 gene.

Therefore, from the study, it was concluded that Spondias mombin stem bark has apoptotic and antioxidant properties.