Immunolocalization of a nuclear protein bound to the sphere organelle during oogenesis and embryogenesis inPleurodeles waltl

Expression of TAFII70 RNA and protein during oogenesis and development of the amphibian Pleurodeles waltl

TAFs are thought to play an essential role in eukaryotic RNA polymerase II transcription by mediating the expression of distinct subsets of genes. TAFII60/70 was studied in yeast, Drosophila and humans: in the present work, we analyzed the homologue PwTAFII70 in Pleurodeles. The gene is expressed in ovarian oocytes and throughout development, and the level of expression decreases in late embryos. The transcripts are localized in the animal hemisphere of the fertilized eggs and in the animal blastomeres of embryos at cleavage; later PwTAFII70 mRNA is expressed in the neural plate and folds. TAFII70 protein, which is present in fertilized eggs and throughout development, progressively shows a lower level of expression starting from the neurula stage.

Localization of antigens PwA33 and La on lampbrush chromosomes and on nucleoplasmic structures in the oocyte of the urodele Pleurodeles waltl: light and electron microscopic immunocytochemical studies

Monoclonal antibodies A33/22 and La11G7 have been used to study the distribution of the corresponding antigens, PwA33 and La, on the lampbrush chromosome loops and nucleoplasmic structures of P. waltl oocytes, using immunofluorescence, confocal laser scanning microscopy and immunogold labeling. The results obtained with these antibodies have been compared with those obtained with the Sm-antigen-specific monoclonal antibody Y12. All these monoclonal antibodies (mAbs) labeled the matrices of the majority of normal loops along their whole length. Nucleoplasmic RNP granules showed a strong staining with the mAbs La11G7 and Y12 throughout their mass, but with the mAb A33/22, they showed only a weak peripheral labeling in the form of patches on their surface. This patchy labeling was confirmed by confocal laser scanning microscopy. Electron microscopy revealed that this patchy labeling might be due to a hitherto undescribed type of submicroscopic granular structure, around 100 nm in either dimension, formed by 10-nm particles. Such granules were observed either attached to the RNP granules or free in the nucleoplasm, but rarely in relation with the normal loop matrices. These 100-nm granules may have a role in the movement of proteins and snRNPs inside the oocyte nuclei for storage, recycling, and/or degradation. Our results also suggest that all the microscopically visible free RNP granules of the nucleoplasm of P. waltl oocytes correspond to B snurposomes. The granules forming the B (globular) loops showed a labeling pattern similar to that of B snurposomes; their possible relationship is discussed.