A STUDY of nucleo-cytoplasmic interactions in pre-embryonic development, at maturation stages in particular, is of great interest. During this period ooplasmic segregation takes place, specific properties of the cortex arise, and the cytoplasm obtains information from the oocyte nucleus which promotes the development of the embryo during all the changes related to fertilization, cleavage and bl...

Background: The meiotic spindle plays an important role in the oocyte during chromosome alignment and separation at meiosis. The zona pellucid (ZP) is a dynamic matrix composed of filaments with the properties that might reflect the history of oocyte cytoplasmic maturation. Since, spindle and ZP in living oocytes are highly birefringent, their structures can be viewed noninvasively by using a P...

Cell cycles in early amphibian embryos are characterized by the absence of G1 and G2 phases. The simple cycle of S phase and mitosis does show similarities with other systems, particularly in the presence of cytoplasmic components advancing nuclei into DNA synthesis and mitosis. Maturation-promoting factor induces nuclear envelope breakdown and subsequent chromosome condensation. Cytoplasmic fa...

During their biogenesis, 40S ribosomal subunit precursors are exported from the nucleus to the cytoplasm, where final maturation occurs. In this study, we show that the protein kinase human Rio2 (hRio2) is part of a late 40S preribosomal particle in human cells. Using a novel 40S biogenesis and export assay, we analyzed the contribution of hRio2 to late 40S maturation. Although hRio2 is not abs...

The autoregulatory loops of the circadian clock consist of feedback regulation of transcription/translation circuits but also require finely coordinated cytoplasmic and nuclear proteostasis. Although protein degradation is important to establish steady-state levels, maturation into their active conformation also factors into protein homeostasis. HSP90 facilitates the maturation of a wide range ...

Background: In vitro maturation (IVM) is a promising treatment option for certain infertile women. Nowadays, with the aid of the Polscope, it has become possible to evaluate zona pellucida (ZP) and spindle as parameters of oocyte quality. The goal was to investigate the relationship between the presence of the meiotic spindle and ZP birefringence with morphology of the in vivo and in vitro matu...

Allelic forms of DRG1/AFG2 confer resistance to the drug diazaborine, an inhibitor of ribosome biogenesis in Saccharomyces cerevisiae. Our results show that the AAA-ATPase Drg1 is essential for 60S maturation and associates with 60S precursor particles in the cytoplasm. Functional inactivation of Drg1 leads to an increased cytoplasmic localization of shuttling pre-60S maturation factors like Rl...

Budding yeast Tsr1 is a ribosome biogenesis factor with sequence similarity to GTPases, which is essential for cytoplasmic steps in 40S subunit maturation. Here we present the crystal structure of Tsr1 at 3.6 Å. Tsr1 has a similar domain architecture to translational GTPases such as EF-Tu and the selenocysteine incorporation factor SelB. However, active site residues required for GTP binding an...