HOMEOBOX AND PAX GENES IN ZEBRAFISH DEVELOPMENT

The fundamental mechanisms of development are strongly conserved among vertebrates from fish to mammals. By exploiting the simple features of zebrafish embryos, it has been possible to analyze the development of cells and morphological subdivisions at a higher resolution than in other vertebrates. Thus, even without a large number of developmental mutants, the zebrafish provides opportunities for analyzing the aspects that may not be accessible for investigation in mammals. Still, its success as a developmental model will strongly depend on the advances made in mutant screening and transgene technology during the next few years. The chapter discusses sequence conservation between zebrafish and mammalian homologs, patterning of the hindbrain, spinal cord, and rostral brain along with expression patterns in mesodermal tissues and signals responsible for establishing the patterns. Many properties of the zebrafish—including small size, large number of embryos, speed of development, and transparency of embryos—are favorable for genetic analysis. In addition, the ability to generate haploids with almost normal embryonic development allows the detection of recessive, early acting mutations without breeding homozygotes. But, the success of zebrafish embryos as a developmental model will strongly depend on the advances made in mutant screening and transgene technology during the next few years. © 1994 Academic Press Inc.