Laboratory of Stem Cell Biology:3

About	Group under the leadership of Dr. Ludmyla Kolchinskaya.	Group under the leadership of Prof. Evgeniya V Pushchina	Group under the leadership of Dr. Igor Prudnikov and Dr Vladimir Tsyvkin	Some results of Dr. Igor Prudnikov and Dr Vladimir Tsyvkin

Evgeniya V Pushchina investigated the structural and neurochemical organization and makes the description of basic histogenetic processes (proliferation, migration and neuronal cell differentiation) during the brain forming in fish. Morphological organization of brain structures in the adult fish has the signs of fetal organization. It seems conceivable, that during postembryonic development in teleost fishes some neurotransmitters and gaseous mediators (NO and H2S) act as factors, which initiate and regulate the cellular and the tissues processes of genetic program during the brain development. Evgeniya V Pushchina supposed the existence of epigenetic control of adult neurogenesis in fish brain via highly coordinated nonsynaptic cell–cell signaling. It engages the neurotransmitters GABA and dopamine whose extra cellular concentrations depend on neuroblasts number and high affinity uptake systems in neural stem cells. Neuroblasts release GABA providing a negative feedback control of stem cell proliferation and instructing them on the size of the neuroblast pool. Scientists suggested that in fish brain there is a strong control mechanism of neuroblast production. Peculiarities of distribution of classical neuromediators (GABA, catecholamines) and gasotransmitters (NO and H2S) are directly connected with ability of the fishes brain to grow during the animal entire life. Evgeniya V Pushchina think that some classical neuromediators (GABA, catecholamines) and gasotransmitters (NO and H2S) not only regulate functional activity of neurons and modulate synaptic transmission in mature neural networks, but also are regarded as inductors of the fishes brain development (morphogenetic factors) in postembryonic ontogenesis. She proposed that dopamine and GABA act as homeostatic signals to regulate neuroblast production. This confirmation is proved by finding of the phenotypically immature elements, expressing the above mentioned molecules in proliferating brain areas, in the three-year-old salmon brain, and of elements, which owe morphology of radial glia. The presences of enzymes, synthesizing gasotransmitters in the brain areas, which are expressing proliferative cell nuclear antigen PCNA, have proved their participation in regulation of postembryonic neurogenesis. A superficially located periventricular proliferative area with PCNA-immunopositive (PCNA+) cells, which corresponds to the pallial periventricular zone (PVZ) of other fish species, including its dorsal, lateral, and medial compartments, is discovered in the telencephalon of the juvenile masu salmon Oncorhynchus masou. The PCNA+ cells are also identified in the parenchyma of the masu salmon intact brain, and their maximum concentration is observed in the medial zone. After a mechanical injury, the zones of induced neurogenesis—neurogenic niches and sites of secondary neurogenesis surrounded by radial glial fibers—appear in the masu salmon telencephalon. The PVZ of the juvenile masu salmon pallium contains clusters of undifferentiated HuCD-immunopositive (HuCD+) neurons. A change in the HuCD+ cell topography is observed in the mechanically injured masu salmon telencephalon, namely, neurogenic niches in the lateral zone and an increase in the cell distribution density and cell migration patterns in the medial zone.

The brain of fish has a unique vertebrates feature - it grows with the organism during all life. In connection with this fish is a model object for the study of embryonic and postembryonic development of the CNS, to influence these processes of various factors. It is shown that in the brain of adult vertebrate a system of cambial elements remains, the activity of which allows replenishing the population of neurons and glial cells in the course of a long period after birth. Currently the mechanisms of pre-and postnatal morphogenesis of the brain in the fish, which for a long time secures the larval state, virtually have not been studied

As you can see the brain plasticity exists in the form of returning into embryonic life or childhood time.

The principal articles.

• Evgeniya V Pushchina, Dmitry K Obukhov, Anatoly A Varaksin. Features of adult neurogenesis and neurochemical signaling in the Cherry salmon Oncorhynchus masou brain. 2013 Neural regeneration research v.8, #1, P.13.

• EV Pushchina, M Yu Fleishman, SS Timoshin. Proliferative zones in the brain of the Amur sturgeon fry. Interactions with neuromeres and migration of secondary matrix zones. Russian Journal of Developmental Biology. 2007, v. 38, # 5, P. 286-293.

• Evgeniya V Pushchina, Anatoly A Varaksin, Sachin Shukla and Dmitry Obukhov. The neurochemical organization and adult neurogenesis in the Masu salmon brain. Book: Nova Sci Publisher, NY, 2017.

• Evgeniya V Pushchina, Sachin Shukla, Anatoly A Varaksin, Dmitry K Obukhov. Cell proliferation and apoptosis in optic nerve and brain integration centers of adult trout Oncorhynchus mykiss after optic nerve injury. 2016, Neural regeneration research v.11,#4, P.578.