[NESPRINS--nuclear envelope proteins ensuring integrity].

This review describes the nesprins (nuclear envelope spectrin-repeat proteins), which are recently discovered family of nuclear envelope proteins. These proteins play an important role in maintaining the cellular architecture and establish the link between the nucleus and other sub-cellular compartments. Many tissue-specific diseases including lipodystrophies, hearing loss, cardiac and skeletal myopathies are associated with nesprins mutations. These proteins comprise of multiple tissue specific isoforms which contain spectrin repeats providing interaction of nesprins with other nuclear membrane proteins, cytoskeleton and intranuclear matrix. We summarize recent findings and suggestions about nesprins structural organization and function inside the cell. Human diseases caused by abnormal nesprins expression are also described.

[Changes in Xenopus oocyte nucleus and cytoplasm organization after actin filaments depolymerization by latrunculin].

Actin-containing filaments have been visualized inside the Xenopus oocyte nuclei due to combination of fluorescence and transmission electron microscopy. It has been shown that these filaments contact with nucleoli, spherical bodies and nuclear pore complexes. The incubation of oocytes with actin-depolymerizing latrunculin causes membrane vesiculation in the cytoplasm, and disruption of the nucleoplasm and nuclear envelope integrity. We suppose that actin-containing filaments belong to crucial cell components which are involved in coordination of nuclear-cytoplasmic interactions as well as distribution and transport of intranuclear components in growing Xenopus oocytes.

[Structural organization, functions and dynamics of nuclear pores].

This review summarized data on the morphological and biochemical analysis of nuclear pore complexes, which are complex organelles providing the route of passive and active nuclear-cytoplasmic transport to different molecules in the eukaryotic cell. The morphology and functional role of nuclear pores in higher and lower eukaryotes, and molecular aspects of the import and export of molecules from the nucleus are described in addition to factors involved in the regulation of these process. Special attention has been paid to sequential steps of the nuclear pore assembly in vitro and in vivo.

[Morphometrical analysis of endoplasmic reticulum dynamics in growing amphibian oocytes].

Morphological analysis of endoplasmic reticulum (ER) dynamics was carried out in early amphybian oocytes at different stages of their development. Comparative morphometric analysis of ER membrane relative surface area and relative volume has shown that at the 1st-2nd stages of oogenesis the accumulation of ER membranes occurred mainly in the peripheral region of the cell cytoplasm. At the 3rd-4th stages of oocyte growth characterized by active transcription, the increase in the relative volume of ER and relative surface area of ER membranes occurs in the middle and near-nuclear region of cytoplasm, and reduction of these parameters takes place in the peripheral part of the cell. Simultaneously observed fusion of numerous ER vesicles with the outer nuclear membrane may serve as an evidence of active formation of new fragments of nuclear envelope. The 5th-6th stages of oocyte development are characterized by an increase in the relative volume of ER in the whole oocyte. It has been supposed that the revealed reorganization of endoplasmic reticulum in growing amphibians oocytes might be due to yolk accumulation (vitellogenesis), redistribution of calcium ions, and synthesis and storage of lipids and proteins. These processes are necessary for the future embryo development, and also for assembly of new fragments of growing nuclear envelope.

[Structural organization and possible functional role of annulate lamellae containing cytoplasmic pores].

This review is devoted to annulate lamellae, a specific compartment of endoplasmic reticulum that occurs, presumably, in actively growing and rapidly dividing cells (oocytes, embryonic and tumor cells). We summarized both earlier and recent data on the dustribution of annulate lamellae in various cell types, on their morphology, and the distribution of interaction with intracellular structures at various treatments. As the annulate lamellae contain cytoplasmic pore complexes, a special attention was paid to their relation with nuclear pores. Possible functions of the annulate lamellae in intracellular processes and, particularly, in nuclear envelope assembly, are discussed.