Zebrafish/mouse somatic cell hybrids for the characterization of the zebrafish genome

Molecular Mechanisms of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Cardiovascular Embryotoxicity

2,3,7,8 Tetrachlorodibenzo-p-dioxin (TCDD) and related planar halogenated aromatic hydrocarbons are widespread environmental contaminants and potent developmental toxicants. Hallmarks of embryonic exposure include edema, hemorrhage, and mortality. Recent studies in zebrafish and chicken have revealed direct impairment of cardiac muscle growth that may underlie these overt symptoms. TCDD toxicity is mediated by the aryl hydrocarbon receptor, but downstream targets remain unclear. Oxidative stress and growth factor modulation have been implicated in TCDD cardiovascular toxicity. Gene expression profiling is elucidating additional pathways by which TCDD might act. We review our understanding of the mechanism of TCDD embryotoxicity at morphological and molecular levels.

The first radiation hybrid map of a perch-like fish: the gilthead seabream (Sparus aurata L)

Among Teleosts, Perciformes are the largest order of fishes and include numerous species of commercial importance. Perciformes also comprise species of primary interest for evolutionary studies and analysis of the sex determination systems and sex chromosome plasticity. Unfortunately, genomics tools and resources for Perciformes remain to be developed. Here, we report the production of a seabream whole-genome radiation hybrid (RH) panel in which quality was ascertained by the construction of a 2-Mb-resolution RH map. The map encompasses 440 markers (288 microsatellites, 82 gene-based markers, and 70 STS) suitable for linkage analysis and comparative mapping studies. Achievement of a RH panel and a whole-genome RH map should contribute to establishing seabream as a fish model among the Perciformes and should be of importance in aquaculture for marker-assisted selection, improvement of growth performance, and disease management. Development of RH maps in a cost-effective manner for other fishes with the described methodology will offer a powerful approach in aquaculture and will provide extended capabilities for comparing vertebrate genome evolution.

Realizing the potential of zebrafish as a model for human disease

The value of the zebrafish (Danio rerio) as a model for human disease has been substantiated by a number of recently published papers. Several zebrafish mutants with "human" diseases have been found, spanning a variety of human pathologies. These successful studies utilizing the zebrafish have been made possible by the development of key reagents such as YAC, PAC, and BAC libraries, as well as radiation hybrid panels. With the further establishment of new tools and access to the newly generated resources, the zebrafish is poised to serve as a novel model for human disease.

Dissecting hematopoiesis and disease using the zebrafish

The study of blood has often defined paradigms that are relevant to the biology of other vertebrate organ systems. As examples, stem cell physiology and the structure of the membrane cytoskeleton were first described in hematopoietic cells. Much of the reason for these successes resides in the ease with which blood cells can be isolated and manipulated in vitro. The cell biology of hematopoiesis can also be illuminated by the study of human disease states such as anemia, immunodeficiency, and leukemia. The sequential development of the blood system in vertebrates is characterized by ventral mesoderm induction, hematopoietic stem cell specification, and subsequent cell lineage differentiation. Some of the key regulatory steps in this process have been uncovered by studies in mouse, chicken, and Xenopus. More recently, the genetics of the zebrafish (Danio rerio) have been employed to define novel points of regulation of the hematopoietic program. In this review, we describe the advantages of the zebrafish system for the study of blood cell development and the initial success of the system in this pursuit. The striking similarity of zebrafish mutant phenotypes and human diseases emphasizes the utility of this model system for elucidating pathophysiologic mechanisms. New screens for lineage-specific mutations are beginning, and the availability of transgenics promises a better understanding of lineage-specific gene expression. The infrastructure of the zebrafish system is growing with an NIH-directed genome initiative, providing a detailed map of the zebrafish genome and an increasing number of candidate genes for the mutations. The zebrafish is poised to contribute greatly to our understanding of normal and disease-related hematopoiesis.