Environmentally relevant concentrations of Roundup® WG affect ovarian maturation-associated parameters and vitellin
Madson Silveira de Melo1, Vanessa da Silva de Castro1, Yara Maria Rauh Müller1
1Departamento de Biologia Celular, Embriologia e Genética, Universidade Federal de Santa Catarina, Florianópolis, 88040-900, Brazil.
Abstract:
Glyphosate-based herbicides are widely detected in freshwater systems; however, their sublethal effects on the reproduction of non-target organisms, such as crustaceans, remain poorly understood. We investigated the impact of 14-day exposure to environmentally relevant concentrations of Roundup®WG (RWG) (0.065 and 0.28 mg/L) on ovarian maturation, using the non-target freshwater prawn Macrobrachium potiuna as a model. Somatic growth and gonadosomatic index were unaffected, indicating no overt systemic toxicity. However, pronounced alterations were observed at cellular and biochemical levels. Morphometric analyses revealed increased cell area across previtellogenic (PVO) and vitellogenic (VO) stages, accompanied by reduced nucleus area and altered nucleus-to-cell area ratio in PVO and VO, particularly at the highest concentration. Histochemical analyses demonstrated stage-specific alterations in carbohydrates and total proteins. PVO showed increased carbohydrate and protein reactivity, indicating premature accumulation of energetic substrates. VO exhibited reduced carbohydrates but enhanced total proteins, suggesting qualitative shifts in yolk biochemical composition rather than increases in yolk volume. Acidic polysaccharide content was reduced in mature oocytes (MO) at the highest concentration, indicating possible impairment in cytoplasmic structural organization. Increased vitellin-like immunoreactivity was observed at both RWG concentrations in PVO and MO, but only at the lower RWG concentration in VO. Despite unchanged oocyte stage distribution, the combined morphometric and biochemical alterations indicate disrupted maturation dynamics and compromised oocyte biochemical balance. These findings demonstrate that RWG induces sublethal but significant toxicity in decapods through interference with oocyte growth and yolk biochemical balance, highlighting the sensitivity of histological biomarkers for early detection of RWG-induced ovarian toxicity.
