Worm Breeder's Gazette 9(1): 68
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
In Caenorhabditis viability and fertility is observed after treatment with DES. The decrease in life span is associated with senescent morphology of meiotic prophase nuclei, such that nuclei from young and old specimens cannot be differentiated. Aging in oocytes at the pachytene stage of meiotic prophase is manifested by nucleo-cytoplasmic aberrations, increased density of the nucleoplasm and cytoplasm and decrease in numbers of mitochondria. Increasing concentrations of DES are characterized by concomittant decrease in fertility and increased production of abnormal gametes. At DES concentrations higher than 1.25 g/ml, synaptonemal complexes( SC) are absent from the nuclei, thus, effective pairing and segregation of homologous chromosomes is not possible. The absence of SCs may be the result of: 1) a premeiotic colchicine effect that influences pairing of chromosomes; 2) changes in the structure of the DNA due to DES binding that results in changes in expression of the DNA; and 3) changes in temporal DNA synthesis in response to DES. Since the SC is essential for regulating pairing and subsequent separation of bivalents, the lack of an SC explains the loss of fertility, due to the production of unbalanced gametes, observed in DES treated specimens.