The long-term goal of this research is to understand the relationship between structure and function in chromosomes and other organelles of the animal cell nucleus. The first objective is to use the giant "lampbrush" chromosomes found in frog oocytes to understand how chromosomes in general are organized at the molecular level. When frog sperm are injected into the nucleus of the frog oocyte, they transform into giant chromosomes like those already present in the nucleus. Similar injection experiments will be carried out with human sperm, as to produce giant human chromosomes for genetic and molecular analysis. Individual genes can be localized on lampbrush chromosomes by fluorescent in situ hybridization of nucleic acid probes, and the proteins associated with their RNA products can be visualized with fluorescent antibodies. In this way the structure of the chromosome can be accurately correlated with its molecular composition. The second objective is to study the organelles in the nucleus involved in processing of RNA. Almost all RNA molecules made in the nucleus are cut into smaller molecules before export to the cytoplasm, and many undergo multiple cuts and rejoining of parts. The machinery for carrying out these reactions is assembled and stored in several structures in the nucleus, of which the nucleolus, the nuclear speckles, and the coiled bodies are the most prominent. The movement of RNA and protein molecules to the nucleolus, the speckles, and the coiled bodies will be examined in the frog oocyte nucleus using fluorescent molecules as probes. These studies will provide insight into the normal trafficking of macromolecules within the nucleus, and should help to define the changes in trafficking that occur during viral infection and certain hereditary diseases.