The use of herbicides for agricultural and aquatic weed control has increased worldwide. These substances are potentially toxic pollutants because they induce the production of reactive oxygen species for biological systems and exert oxidative stress in nontarget organisms living in the treated aquatic systems. Recent evidence suggests differences in the toxicity of glyphosate in the form of an active ingredient compared to the toxicity of glyphosate in combination with surfactants, such as those found in commercial formulations. In Mexico, one of the most widely used glyphosate-based herbicides is Yerbimat, which has agricultural as well as aquatic weed control applications. However, there are no aquatic toxicity data, particularly regarding native fish. Therefore, we determined the acute toxicity of commercial-formulation Yerbimat in a static bioassay at 96 h (LC(50)). We also determined its toxicity at 96 h in sublethal concentrations to assess the lipid peroxidation levels (LPX), catalase activity, hepatic glycogen content, and histological damage in the liver and gills of the fish Goodea atripinnis associated with chronic exposure (75 days). The LC(50) was 38.95 ± 0.33 mg/L. The results of the short-term exposure study indicate that Yerbimat can potentially induce oxidative stress in G. atripinnis, because LPX was increased in the gills and liver. Catalase activity was reduced in the gills but increased in the liver, whereas hepatic glycogen was depleted. Chronic exposure was associated with histopathological damage in the gills and liver, some of which was irreversible. Yerbimat represents a potential risk for aquatic biota; therefore, we recommend that its application be carefully considered.

No abstract

The gonadal health status of the chocolate clam Megapitaria squalida collected from the Santa Rosalía mining port and San Lucas beach (reference site), Gulf of California, Mexico, was assessed through histological analysis of the reproductive tissue, from which the histopathological alteration index (HAI) was determined. In addition, copper and iron accumulation in tissue was revealed using histochemical techniques. Our results showed a large presence of copper (30%) and iron (45%) only in the gonad tissue of clams from Santa Rosalía, in which histopathological alterations observed were inflammatory responses, degenerative-progressive processes, cell death, and response to infectious agents. The HAI was significantly higher in Santa Rosalía specimens (mean ± SE, 72.18 ± 6.12) than in San Lucas clams (4.60 ± 1.07). At San Lucas beach, a higher prevalence of histopathological alterations occurred in clams in the spent stage (43.2%) and in autumn (18.4%) and winter (17.8%) in concordance with the normal reproductive rest period, whereas at Santa Rosalía a higher prevalence occurred in clams at the ripe stage (76.9%) and in spring (83.7%). In conclusion, our results showed the deteriorated health condition of gonads in M. squalida from the Santa Rosalía mining port, which suggests there is a relationship with chronic exposure to local high levels of heavy metals. The high prevalence and intensity of histopathological alterations in the gonad suggest a strong adverse effect on gametogenesis, gamete quality, and, ultimately, in the reproductive potential of M. squalida at this site.

No abstract

Se compara la morfología lingual de murciélagos insectívoros Tadarida brasiliensisis y Balantiopteryx plicata buscando estructuras posiblemente relacionadas con el tipo de alimentación. La lengua de T.brasiliensis tiene un prominente pliegue dorsal tapizado por papilas muy queratinizadas. La de B. plicata carece del pliegue dorsal y de las papilas córneas. Ambas especies tienen en común papilas filiformes, fungiformes y circunvaladas que se arreglan de forma similar. Las filiformes tapizan la mayor parte de la superficie lingual; las fungiformes se encuentran en el dorso y lateralmente en una línea longitudinal; las circunvaladas son las más grandes y hay un par en la parte posterior. Histológicamente presentan el arreglo de los tejidos que corresponde de manera general para el humano y otros mamíferos. De las dos especies solo B. plicata presenta glándulas mucosas de posición ventral. Ambas tienen un par de nódulos linfoides pequeños y simétricos. El pliegue dorsal en T. brasiliensis y los nódulos linfoides de ambas especies son características descritas por primera vez en el orden Chiroptera. La lengua de las dos especies tiene función intraoral (Tipo I). Al parecer no existen estructuras especializadas que puedan relacionarse con la insectivoría. El pliegue de T. brasiliensis posiblemente es característico del género o la familia pero se requieren estudios adicionales para confirmar esto así como también su función.