Intranuclear ubiquitin-immunopositive structures in human substantia nigra neurons

Marinesco bodies were discovered in substantia nigra neurons of human brain in 1902. The relationships between these intranuclear inclusions and the other structures of the cellular nucleus are still obscure. The aim of this study is to elucidate the morphological and cytochemical peculiarities of intranuclear ubiquitin-immunopositive bodies in the substantia nigra neurons of human brain and to evaluate the interconnections of these peculiarities with nucleolus by means of light microscopy, immunocytochemistry, and confocal laser microscopy. It is found that up to 20% of neurons in substantia nigra of human brain contain ubiquitin-immunopositive Marinesco bodies. These rounded structures are 1–8 μm—more often 2–4 μm—in diameter. Only one-third of them are tightly adjacent to the nucleolus. By a method of silver impregnation of argentophilic proteins associated with nucleolar organizer, the absence was shown of argentophilic proteins, which are characteristic for the nucleolus, in Marinesco bodies. Special ubiquitin-positive substantially smaller structures (less than 1 μm) are revealed in the neurons’ nuclei along with Marinesco bodies. These structures are probably the initial forms in the formation of Marinesco bodies. The existence of two types of ubiquitin-immunopositive intranuclear bodies is revealed by means of confocal microscopy: one has high intensity of immunofluorescence, and the other has low intensity. Heterogeneous distribution of immunopositive product is characteristic of the former. The presence of DNA in Marinesco bodies is detected by using SYTOX Green fluorescent dye. The absence of peripheral heterochromatin zone and weak susceptibility to toluidine blue together with the presence of DNA and the absence of argentophilic proteins suggests substantial structural and chemical differences between Marinesco bodies and nucleoli, which argues against the idea that the detected bodies are modified nucleoli.     

Nucleolin in Neurons of the Human Substantia Nigra

Using immunocytochemistry and confocal laser microscopy, the distribution of nucleolin (protein C23) in neurons of the human substantia nigra was investigated. Fragments of the human midbrain (n = 8) with the verified lack of neurodegeneration were used in the study. The material was fixed in zinc ethanol formaldehyde, a special fixative that provides high preservation of antigenic determinants. New morphological data on the distribution of nucleolin in neurons of the human substantia nigra were obtained. Nucleolin was found in the nucleolus and nucleoplasm of dopaminergic neurons but not in the cytoplasm or cell surface. In the nucleolus and nucleoplasm, protein C23 is distributed irregularly in the form of some accumulations (clumps) with fuzzy borders. Moreover, nucleolin distribution varied in structurally similar neurons containing cytoplasmic neuromelanin. The Marinesco bodies typically not exhibiting nucleolin expression were identified in the nucleus, in addition to nucleoli, by confocal laser microscopy with simultaneous use of transmitted light detector. The findings can contribute to elucidation of the role of nucleolin in the specific functions of normal dopaminergic neurons in the human substantia nigra and assessment of probable involvement of C23 in the development of nucleolar stress and neurodegeneration.     

Age-Related Changes in Microglia of the Rat Spinal Cord

Journal of Evolutionary Biochemistry and Physiology - The aim of this study was to evaluate age-related changes in microglial cells in various regions of the cervical spinal cord in young (4...     

Involvement of Glutamine Synthetase in the Development of Hyperbaric Oxygen Seizures

Journal of Evolutionary Biochemistry and Physiology - Hyperbaric oxygen (HBO2) causes a toxic effect on the central nervous system via poorly understood mechanisms. The aim of this study was to...     

Erratum to: The original online version of the following articles was revised: the issue date is not January 2020, but January 2021

Journal of Evolutionary Biochemistry and Physiology - A Correction to this paper has been published: https://doi.org/10.1134/S0022093021020216     

Vascularization and Development of Cytoarchitectonics in the Human Neocortical Rudiment

The development of cytoarchitectonics of the brain rudiments in mammals is accompanied by the formation of an intracerebral vascular network. The relationship between these two processes is insufficiently clear. We studied the development of blood vessels and cytoarchitectonics in the neocortical rudiment of 6- to 13-week old human embryos. The light and electron microscopy methods were used, as well as histochemical visualization of NADPH-diaphorase in the vessel cells. The endothelium proliferation was evaluated using antibodies to proliferating cell nuclear antigen. Starting from week 8 of development, the tangentially oriented vessels formed a intraneural network in the ventricular zone of the rudiment, which appears to restrict the motility of neuroepithelial cells. The basal membrane was initially absent, and the neuroepithelial cells were in direct contact with the endothelial cells. During week 9 of development, the tangentially oriented vessels appeared in the intermediate zone. Formations similar to glial legs with short regions of the basal membrane adjoined the walls of inter- and intraneural vessels (note that, according to the published data, glial fibrillary acidic protein is not yet visualized at this stage). Angioarchitectonics depended little on the cell population density in different zones of the rudiment; specifically, the cortical plate did not contain tangentially oriented vessels until week 12–13 of development. The data we obtained suggest that the blood vessels fulfill a special morphogenetic function in the developing neocortex.     

Intermediate filament proteins in tanycytes of the third cerebral ventricle in rats during postnatal ontogenesis

Cytoskeletal intermediate filaments (IF) are composed of proteins able to form homo- and heterodimers, while their repertoire can change during cell differentiation. Data on the IF protein composition in tanycytes lining the mammalian third cerebral ventricle are still discrepant. The aim of this study was to investigate age-related changes in the IF protein composition in tanycytes of the third cerebral ventricle in Wistar rats at different ages (7-, 14-, and 30-day-old pups and 4–5-month-old adults; n = 26), using immunocytochemistry and confocal laser microscopy. In adult animals, tanycytes were shown to express IF proteins vimentin, GFAP, and nestin. In different types of tanycytes GFAP and nestin begin to be synthesized at different postnatal ages. For example, in α1 tanycytes GFAP is already present in 7-day-old animals, while in β1 tanycytes it appears only by day 30 of postnatal development. Meanwhile, vimentin is an essential IF component at all ages studied. A comparison of our data with the results obtained on other animal models suggests the existence of species-specific differences in the IF protein repertoire in tanycytes.