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J Morphol. 2018 May;279(5):609-615. doi: 10.1002/jmor.20796. Epub 2018 Jan 31.

Electron microscopic characterization of nuclear egress in the sea urchin gastrula.

Author information

1
Department of Biology, College of Staten Island, City University of New York, Staten Island, New York, United States of America.
2
Center for Developmental Neuroscience, College of Staten Island, City University of New York, Staten Island, New York, United States of America.
3
Program in Neuroscience, The Graduate Center, City University of New York, New York, New York, United States of America.

Abstract

Nuclear egress, also referred to as nuclear envelope (NE) budding, is a process of transport in which vesicles containing molecular complexes or viral particles leave the nucleus through budding from the inner nuclear membrane (INM) to enter the perinuclear space. Following this event, the perinuclear vesicles (PNVs) fuse with the outer nuclear membrane (ONM), where they release their contents into the cytoplasm. Nuclear egress is thought to participate in many functions such as viral replication, cellular differentiation, and synaptic development. The molecular basis for nuclear egress is now beginning to be elucidated. Here, we observe in the sea urchin gastrula, using serial section transmission electron microscopy, strikingly abundant PNVs containing as yet unidentified granules that resemble the ribonucleoprotein complexes (RNPs) previously observed in similar types of PNVs. Some PNVs were observed in the process of fusion with the ONM where they appeared to release their contents into the cytoplasm. These vesicles were abundantly observed in all three presumptive germ layers. These findings indicate that nuclear egress is likely to be an important mechanism for nucleocytoplasmic transfer during sea urchin development. The sea urchin may be a useful model to characterize further and gain a better understanding of the process of nuclear egress.

KEYWORDS:

cell ultrastructure; development; nuclear envelope

PMID:
29383750
DOI:
10.1002/jmor.20796
[Indexed for MEDLINE]

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