ABSTRACT
The nucleus ofvitellogenic oocytes of the yellow mealworm, Tenebrio molitor, contains a karyosphere that consists of the condensed chromatin embedded in an extrachromosomal fibrogranular material. Numerous nuclear bodies located freely in the nucleoplasm are also observed. Amongst these bodies, counterparts of nuclear speckles (= interchromatin granule clusters, IGCs) can be identified by the presence of the marker protein SC35. Microinjections of fluorescently tagged methyloligoribonucleotide probes 2'-O-Me(U)22, complementary to poly(A) tails of RNAs, revealed poly(A)+ RNA in the vast majority of IGCs. We found that all T. molitor oocyte IGCs contain heterogeneous ribonucleoprotein (hnRNP) core protein Al that localizes to IGCs in an RNA-dependent manner. The extrachromosomal material of the karyosphere and a part of nucleoplasmic IGCs also contain the adapter protein Aly that is known to provide a link between pre-mRNA splicing and mRNA export. The essential mRNA export factor/receptor NXF1 was observed to colocalize with Aly. In nucleoplasmic IGCs, NXF1 was found to localize in an RNA-dependent manner whereas it is RNA-independently located in the extrachromosomal material of the karyosphere. We believe our data suggest on a role of the nucleoplasmic IGCs in mRNA biogenesis and retention in a road to nuclear export.
Subject(s)
Chromatin , Heterogeneous-Nuclear Ribonucleoprotein Group A-B/metabolism , Nucleocytoplasmic Transport Proteins/metabolism , Oocytes , RNA, Messenger/metabolism , Tenebrio , Active Transport, Cell Nucleus/physiology , Animals , Antibodies, Monoclonal , Chromatin/metabolism , Chromatin/ultrastructure , Coiled Bodies/metabolism , Coiled Bodies/ultrastructure , Heterogeneous Nuclear Ribonucleoprotein A1 , Immunoblotting , Microscopy, Electron, Transmission , Oocytes/metabolism , Oocytes/ultrastructure , RNA Splicing , Tenebrio/metabolism , Tenebrio/ultrastructure , Vitellogenesis/physiologyABSTRACT
Heat shock protein 70 (Hsp70) is considered not only as a cytosolic stress protein, but also as an extracellular molecule with immunomodulatory and signaling functions that play a role in adaptation to stress on cellular and systemic levels. The active involvement of mast cells in adaptation to stress may be associated with the presence of Hsp70 in secretory granules. Using immunoelectron microscopy, we showed that Hsp70 localized in secretory granules of rat pericardial and peritoneal mast cells. Localization of Hsp70 in rat perinoneal mast cells isolated by centrifugation on Percoll was confirmed by immunoblotting. The proposed involvement of mast cells in production of extracellular Hsp70 and possible functions of Hsp70 inside the mast cells granules are discussed.
Subject(s)
HSP70 Heat-Shock Proteins/physiology , Mast Cells/cytology , Pericardium/cytology , Peritoneum/cytology , Signal Transduction/physiology , Adaptation, Physiological , Animals , Blotting, Western , Cell Separation , Centrifugation, Density Gradient , Mast Cells/physiology , Microscopy, Immunoelectron , Pericardium/physiology , Peritoneum/physiology , Rats , Rats, Wistar , Secretory Vesicles/physiologyABSTRACT
By immunohistochemical and immunocytochemical methods localization of Substanse P (SP) and FMRFamide in the atrium of the snail Achatina fulica was investigated. Nerve fibers innervating the snail atrium contact tightly with the granular cells (GC) situated between muscle and endocardial cells, forming neuroendocrine units. Both neuromediators were found in the cells of the neuroendocrine units. By immunohistochemistry SP- and FMRFamide-immunoreactive material was revealed in the granules of the atrial GC. Elecrtonmicroscopical immunocytochemistry has confirmed the presence of SP- and FMRFamide-immunoreactive material in the granules of the GC and shown their presence in the neurosecretory granules of the nerve endings contacting both the atrial GC and cardiomyocytes.
