Antecedentes: Pleutorus ostreatus y P. pulmonarius producen compuestos tóxicos para nematodos y por ende potencialmente útiles para biocontrol; algunos de estos compuestos se originan en estructuras denominadas toxocistos.Objetivo: Describir las características morfológicas de las estructuras tipo toxocisto formadas in vitro por Pleurotus ostreatus y P. pulmonarius para contribuir al conocimiento de los caracteres morfológicos del género.Métodos: Las cepas de Pleurotus se hicieron crecer en paja de trigo y en placa con agar con extracto de malta (EMA) y agar con papa y dextrosa (PDA). El micelio crecido se procesó para su observación bajo microscopía electrónica de barrido.Resultados y conclusiones: El micelio de ambas especies, desarrollado en ambos sistemas, produce estructuras esféricas, pediceladas, morfológicamente similares. Aunque la morfología de estas estructuras es similar a las de los toxocistos descritos previamente para estas especies y para otras de Pleurotus; se consideran como estructuras tipo toxocistos en tanto no se corrobore la producción de compuestos nematotóxicos y sus funciones.

A wide variety of biological functions, including those involved in the morphogenesis process of basidiomycete fungi, have been attributed to laccase enzymes. In this work, RNA interference (RNAi) was used to evaluate the role of the laccase (lacc2) gene of Pleurotus ostreatus PoB. Previously, transformant strains of P. ostreatus were obtained and according to their level of silencing they were classified as light (T7), medium (T21) or severe (T26 and T27). The attenuation of the lacc2 gene in these transformants was determined by RT-PCR. Silencing of lacc2 resulted in a decrease in laccase activity between 30 and 55%, which depended on the level of laccase expression achieved. The silenced strains (T21, T26, and T27) displayed a delay in the development of mycelium on potato dextrose agar (PDA) medium, whereas in the cultures grown on wheat straw, we found that these strains were incapable of producing aerial mycelium, primordia, and fruiting bodies. Scanning electron microscopy (SEM) showed the presence of toxocyst-like structures. The highest abundance of these structures was observed in the wild-type (PoB) and T7 strains. However, the abundance of toxocysts decreased in the T21 and T26 strains, and in T27 they were not detected. These results suggest that the presence and abundance of toxocyst-like structures are directly related to the development of fruiting bodies. Furthermore, our data confirm that lacc2 is involved in the morphogenesis process of P. ostreatus.

Laccases are enzymes that have a great potential for use in breaking down toxic compounds. Fungal laccases show high enzymatic activity, especially those produced by basidiomycetes. Depending on the culture conditions and the strain used, a variety of isoenzymes and/or enzymatic activities can be obtained. In this study, extracellular laccase enzymes produced by Pleurotus ostreatus was identified in a submerged culture (SmF), with and without copper sulphate as a chemical inducer, and in a solid-state culture (SSF), using wheat straw as natural inducer. This study was conducted to observe the expression of the enzymes produced under the culture conditions tested and their persistence during the culture, as well as the extracellular activity produced and the correspondence that the isoenzymes presented between the intracellular and extracellular media. A positive effect of the inducers on the specific laccase activity was observed either in SmF with copper sulphate or SSF (41.11 and 40.43 UI/mg protein, respectively), compared with that obtained in SmF without copper sulphate (2.87 UI/mg protein). This effect was different only at the time when the highest activity appeared (360 and 120 h, respectively), showing advantages in SSF. The same three isoenzymes were observed in the three kinds of cultures. The main differences among the laccase profiles reside in the time when they appeared in each culture and only an additional form of lower molecular weight was observed in SSF. The laccase enzymes in the intracellular extracts were equal to those in the extracellular ones. The laccase isoenzymes profiles suggest that the presence of inducers helps in maintaining the activity through the culture time. Key words: Phenol oxidases, basidiomycete, enzymatic activity, copper, wheat straw, solid-state culture (SSF), submerged culture (SMF).

Background: Gasoline, a complex mixture of volatile organic compounds is classified as possibly carcinogenic to humans. Gasoline station attendants, consistently exposed to its hazardous components, may face genotoxic effects. This study aimed to assess the influence of varying work shift durations on DNA damage in gasoline station attendants. Methods: Ninety individuals from three locations in southern M & eacute;xico were studied. Peripheral blood mononuclear cells (PBMCs) were isolated, and DNA damage was assessed using the comet assay. Demographic, occupational, and lifestyle data were collected. Statistical analyses included t-tests, ANOVA, and Pearson correlation. Results: Significant differences in DNA damage parameters were observed between exposed and unexposed groups. The impact of tobacco, alcohol, and exercise on DNA damage was negligible. Extended work shifts (12 and 24 hours) showed heightened DNA damage compared to 8-hour shifts and the unexposed group. A novel finding revealed a modest but significant correlation between DNA damage and job seniority. Conclusion: The study highlights the intricate relationship between occupational exposure to gasoline components, DNA damage, and work shift lengths. Extended shifts correlate with heightened genotoxic effects, emphasizing the importance of personalized safety measures. The significant correlation between DNA damage and job seniority introduces occupational longevity as a determinant in the genetic health of gasoline station attendants. This discovery has implications for implementing targeted interventions and preventive strategies to safeguard workers' genetic integrity throughout their years of service. The study calls for further exploration of unconsidered factors in understanding the multifactorial nature of DNA damage in this occupational setting. (c) 2024 Occupational Safety and Health Research Institute. Published by Elsevier B.V. on behalf of Institute, Occupational Safety and Health Research Institute, Korea Occupational Safety and Health Agency. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).