Exposure to Oil during Meiosis Results in Alterations in Meiotic Chromosomes that are Similar to Age-Related Changes in the Nematode Caenorhabditis elegans

Exposure of young C. elegans nematodes to three different concentrations of oil resulted in changes in the meiotic chromosomes, nucleus, nucleolus, and nuclear envelope associations. Such alterations decreased the viability and fertility of this organism which was used as a biological model. The morphological changes in the “young” group were similar to nematodes that were senescent and post-reproductive. Comparison of meiotic chromosomes at the pachytene stage of meiosis from young, old, and oil-exposed wild-type hermaphrodites were made following three-dimensional electron microscopy reconstruction of serial ultrathin sections. Age-related and oil-exposure related changes included: 1) Induced condensation of chromatin with increased variance in length of chromosomes; 2) Changes in nuclear and nucleolar volume; 3) Increased density of the nucleoplasm; and 4) Absence of Disjunction Regulator Regions, resulting in the loss of control of the segregation of the X-chromosome into gametes during meiosis. Abnormal clustering of the telomeric ends of the chromosomes was present on the nuclear envelope affecting the segregation of the chromosomes during meiosis.