Abstract
Kryptolebias marmoratus ( Rivulus marmoratus till 2004, order Cyprinodontoformes; family Rivulidae) is the only known self‐fertilizing hermaphrodite vertebrate. Because of this uniqueness, there has been great interest in its biology, physiology, developmental biology and genomics along with other basic and applied areas of environmental genomics and molecular carcinogenesis. In laboratory studies, K. marmoratus has shown susceptibility to a number of xenobiotics including carcinogens. Toxicologists are interested in the mechanisms of action of environmental chemicals of contemporary interest such as endocrine disruptors and may consider this as a suitable fish model for the study of chemically induced carcinogenesis. Single short‐term exposure to model chemical carcinogens is sufficient to induce tumourigenesis in K. marmoratus in a relatively short time span. In recent years, considerable data have been generated about gene sequences of K. marmoratus . Laboratory maintenance of K. marmoratus is relatively easy. Gene bank data are readily available, though not as extensive as for zebrafish Danio rerio or Japanese madaka Oryzias latipes . The expressed sequence tag (EST) data, differential display real‐time reverse‐transcriptase polymerase chain reaction and Gene Sequencer 20™ sequencing data have recently been helpful in understanding the genomics and proteomics of this species. Recently, sequences of the oncogene, ras , and tumour suppressor gene, p53 , have been reported in K. marmoratus . The expression of these important genes that play significant roles not only in carcinogenesis but also in other signal transduction pathways was observed to be modulated by environmental endocrine‐disrupting chemicals. Having a large sequence database (cDNA sequences and ESTs), it is expected that the use of a microarray in the near future will open new vistas for this fish with applications in cancer research, aquatic toxicology, endocrinology and genomics. This review discusses potential uses of K. marmoratus in new biotechnological approaches of aquatic toxicology.