Impact of oil-related environmental pollutants on the ovary structure in the freshwater leech Erpobdella johanssoni (Johansson, 1927) (Clitellata: Hirudinea)

Abstract

Toxicity of organic chemical compounds, including benzene, toluene, ethyl benzene and xylene (BTEX), is a major concern because of their induction of adverse effects in organisms, including reproductive abnormalities. In the present study, we investigated impacts of chronic exposure to BTEX at 25 µg L−1 on the ovaries of the freshwater leech Erpobdella johanssoni at the cytological and molecular level. Based on light and transmission electron microscopy, we found that somatic cells and vitellogenic oocytes of the treated animals underwent degenerative changes, such as cytoplasmic vacuolization, mitochondrial alterations, and nuclear DNA condensation, as compared with normal. The comet test supported histological and ultrastructural results and showed that BTEX exposure induced significantly more DNA fragmentation in the ovary cells of treated leeches than in controls (p < 0.0001). Overall, we concluded that BTEX-induced deterioration in ovarian cells suggests the genotoxicity of BTEX on oogenesis in leech, which could impair their reproduction.

Keywords

• BTEX
• toxicity
• reproduction
• leech
• ovary