Natalia Biserova | Lomonosov Moscow State University (original) (raw)

Papers by Natalia Biserova

Frontiers in Systems Neuroscience, 2018

A comparison between the axon terminals of octopaminergic efferent dorsal or ventral unpaired med... more A comparison between the axon terminals of octopaminergic efferent dorsal or ventral unpaired median neurons in either desert locusts (Schistocerca gregaria) or fruit flies (Drosophila melanogaster) across skeletal muscles reveals many similarities. In both species the octopaminergic axon forms beaded fibers where the boutons or varicosities form type II terminals in contrast to the neuromuscular junction (NMJ) or type I terminals. These type II terminals are immunopositive for both tyramine and octopamine and, in contrast to the type I terminals, which possess clear synaptic vesicles, only contain dense core vesicles. These dense core vesicles contain octopamine as shown by immunogold methods. With respect to the cytomatrix and active zone peptides the type II terminals exhibit active zone-like accumulations of the scaffold protein Bruchpilot (BRP) only sparsely in contrast to the many accumulations of BRP identifying active zones of NMJ type I terminals. In the fruit fly larva marked dynamic changes of octopaminergic fibers have been reported after short starvation which not only affects the formation of new branches ("synaptopods") but also affects the type I terminals or NMJs via octopamine-signaling (Koon et al., 2011). Our starvation experiments of Drosophilalarvae revealed a time-dependency of the formation of additional branches. Whereas after 2 h of starvation we find a decrease in "synaptopods", the increase is significant after 6 h of starvation. In addition, we provide evidence that the release of octopamine from dendritic and/or axonal type II terminals uses a similar synaptic machinery to glutamate release from type I terminals of excitatory motor neurons. Indeed, blocking this canonical synaptic release machinery via RNAi induced downregulation of BRP in neurons with type II terminals leads to flight performance deficits similar to those observed for octopamine mutants or flies lacking this class of neurons (Brembs et al., 2007).

Zoology, 2022

А novel type of a complex neuro-glandular brain structure including both nervous and glandular el... more А novel type of a complex neuro-glandular brain structure including both nervous and glandular elements and associated with sensory ones is detected in Pyramicocephalus phocarum plerocercoid (Cestoda: Diphyllobothriidea), parasite of Gadus morua from the White Sea. The brain has two lateral lobes connected by a long cellular median commissure. The brain is tightly surrounded by glandular cells, which receive numerous synapses from the brain neurons. A complex of sensory organs associated with ducts and terminal pores of the frontal glands lies in the scolex tegument. Serotonin, FMRFamide-and GABA-like immunoreactive (IR) neurons are found in the brain, the main nerve cords, and the plexus of the plerocercoid. The innervation of the frontal gland ducts by FMRFamide-IR neurites is detected for the first time proving that they function under control of the nervous system and thus evidencing the eccrine nature of the secretion mechanism. Ultrastructural data show that light, dark and neurosecretory neurons are present in the brain lobes. The median commissure consists of loosely arranged thin parallel axons and several giant and small neurons. The commissure is stratified and penetrated by frontal glandular cells and their processes. Such neuro-glandular morpho-functional brain complex is suggested as a model for Diphyllobothriidae family. Five structural types of sensory organs are described in the scolex of P. phocarum; their colocalization with eccrine gland terminals is supposedly specific for Diphyllobothriidae family. Within the order Diphyllobothriidea, there are significant differences in the architecture of the plerocercoid brain at the family level. We suppose homology of giant commissural neurons among Diphyllobothriidea. Differences between diphyllobothriidean nervous system and that of other cestodes are discussed.

Journal of Morphology, 2020

The brain architecture in four species of tapeworms from order Trypanorhyncha has been studied. I... more The brain architecture in four species of tapeworms from order Trypanorhyncha has been studied. In all species, the brain consists of paired anterior and lateral lobes and an unpaired central lobe. The anterior lobes are united by dorsal and ventral semicircular commissures; the central and lateral lobes are connected by a median and an X-shaped crisscross commissure. In the center of the brain, five well developed compact neuropils are present. The brain occupies a medial position in the scolex pars bothrialis, and the ventral excretory vessels are situated outside the lateral lobes of the brain; the dorsal excretory vessels are located inside the brain and dorsal to the median commissure. The brain possesses four anterior proboscises and four bulbar nerves with myelinated giant axons. The cell bodies of the giant axons are located within the X- commissure and in the bulbar nerves. Highly developed serotonergic neuropils are present in the anterior and lateral lobes; numerous 5-HT neurons are found in the brain lobes including the central unpaired lobe. The X-cross commissure consists of the α-tub-immunoreactive and 5-HT-IR neurites. Eight ultrastructural types of neurons were found in the brain of the 3 species investigated. In addition, different types of synapses were present in the neuropils. Glial cells ensheath the brain lobes, the neuropils, the giant axons and the bulbar nerves. Glia cell processes form complex branching patterns of thin cytoplasmic sheets sandwiched between adjacent neural processes and filling the space between neurons. Multilayer myelin-like envelopes and a mesaxon-like structure have been found in Trypanorhyncha nervous system. The Trypanorhyncha brain architecture was compared with an early basal cestode taxon, the order Diphyllobothriidea. A hypothesis was made about the homology of the anterior brain lobes in order Trypanorhyncha; and the lateral lobes and median commissure are homologous brain structures within the class Eucestoda.
Keywords: neuron, giant axons, glia, neuropils, serotonin, α-tubuline

Zoology, 2023

Phenomenon of exocrine secretion via nervous cells into the host tissue has been discovered in ce... more Phenomenon of exocrine secretion via nervous cells into the host tissue has been discovered in cestodes. The structural mechanism of the neuroactive substance release into the host environment has been studied in details for five cestode species of different orders. Neuroactive substances release from the parasite into the host tissue through specialized “cup-shaped” free nerve endings located in the tegument. The phenomenon is referred to in this article as neuro-exocrine secretion. The free cup-shaped terminals in the tegument are connected structurally and functionally with neurosecretory cells of the peripheral nervous system (PNS). The neurosecretory neurons are characterized by similar ultrastructural features: size and location; diameter of neurosecretory granules; absence of microtubules and mitochondria in the processes. Size of neurosecretory granules was found to decrease from perikaryon towards neurosecretory processes that lead to the tegument. Supposed targets for the neurosecretory neurons in the studied cestodes are the following: (a) eccrine frontal gland ducts, especially their terminal regions involved in release of secretory products; (b) myofibrils of longitudinal and circular muscles in the subtegument region; (c) terminal regions of sensory organs; (d) the basal membrane of the tegument. Besides the discovered excretion vesicles through the cup-shaped terminals, we observed vacuoles derived from the basal membrane of the tegument containing extracellular substances which release into the host tissue. Their possible role in the release of neurosecretory substances is discussed. Considering the data acquired via immunocytochemical methods, there is an assumption about involvement of FMRFamide-like related peptides (FaRPs) in the neuro-exocrine secretion is proposed. Possible functions of neuro-exocrine secretion are discussed in the context of host-parasite interactions.
Key words: neurons, neurosecretion, free nerve terminals, excretory-secretory products, exocrine secretion, parasite-host interactions.

Cell and Tissue Biology, 2008

Until now, there has been no answer to the question of whether specialized glial cells exist in t... more Until now, there has been no answer to the question of whether specialized glial cells exist in the nervous system of platyhelminths. The identification of these cells in parasitic flatworms is difficult due to their organization as parenchymal animals. The goal of this study was to reveal and describe structural elements corresponding to the term glia in the CNS of the parasitic flatworm Grillotia erinaceus (Cestoda: Trypanorhyncha). Three types of glial cells are revealed. The first type consists of fibroblast-like cells located in the cerebral ganglia that contain fibrils and excrete onto the surface fibrillar material and possess desmosomes; the presumable function of fibroblast-like glial cells is the isolation and support of ganglionar neurons. Glial cells of the second type form a myelin-like envelope of giant axons and bulbar nerves of the scolex and have laminar cytoplasm; they are numerous and exceed the number of neurons in the composition of nerves. Glial cells of the third type form multilayer envelopes in the main nerve cords and make contacts with the excretory epithelium; however, specialized junctions with neurons were not found. The existence of glia in other free living and parasitic flatworms is discussed.

J. Parasitol., 2014

The nervous system (NS) of the cestodes Diphyllobothrium dendriticum (Diphyllobothriidea) and Car... more The nervous system (NS) of the cestodes Diphyllobothrium dendriticum (Diphyllobothriidea) and Caryophyllaeus laticeps (Caryophyllidea) was investigated using immunocytochemistry. The GABA neurotransmitter was identified in the NS of both species; GABAergic neurons were detected in the main nerve cords (MC). GABA-like immunoreactive neurons were predominantly unipolar and exhibited more intensive immunoreactivity in the neurite than in the perikaryon. In C. laticeps , GABA-like immunoreactive somas are located in both the MCs and peripheral NS near the longitudinal muscles. The innervation of the body musculature was studied using a combination of antibodies against GABA, serotonin (5-HT), and FMRFamide and with complementary staining of F-actin. In both species, the location of GABAergic neurites is associated with all muscle layers including the subtegumental, longitudinal, transverse, and dorsoventral muscles. The cytomorphology of 5-HTergic motoneurons in the MCs of both species is described and differences in muscle innervation between D. dendriticum and C. laticeps are demonstrated. No evidence for co-localization of GABA with 5-HT or FMRFamide neurotransmitters at any particular neuron was found. Neuropiles in MCs and peripheral NS had separate sets of immunoreactive neurites. A functional role for GABA in muscle innervation is discussed.

Biology Bulletin, 2014

For the first time, the potential immunomodulators prostaglandin E2 and γ-aminobutyric acid (GABA... more For the first time, the potential immunomodulators prostaglandin E2 and γ-aminobutyric acid (GABA) have been revealed in the plerocercoid Diphyllobothrium dendriticum, which is a parasite in the tissues and abdominal cavity of the Baikal omul Coregonus migratorius. The localization of immunomodulators in parasite tissues was compared with the location of typical markers of the nervous system (serotonin (5-HT) and FMRF-amide) and a marker of microtubules (α-tubulin). Prostaglandin E2 was revealed in the cells that are immunoreactive to α-tubulin and are situated in the cortical parenchyma outside the central nervous system (CNS). It is supposed that prostaglandin E2 is produced by the frontal glands and is carried out onto the tegument surface through specialized ducts. Immunoreaction to GABA was revealed in the central and peripheral nervous systems. GABA-ergic neurosomes, the neurites of which form a net on the surface of muscle layers and in the subtegument, were revealed in the cerebral ganglion and main nerve cords. The morphological characteristics for the identification of serotoninergic neurons in the CNS were described.

Acta Biologica Hungarica, 2008

It is still unclear whether flatworms have specialized glial cells. At present there are no speci... more It is still unclear whether flatworms have specialized glial cells. At present there are no special methods available for the identification of glial cells in flatworms. The aim of this research was to carry out detailed investigations of the CNS in two species of cestodes, and to get an idea whether these cells may fit into the concept of glia. Three types of glial cells have been found in Grillotia erinaceus: (1) fibroblast-like cells in the cerebral ganglion (CG); (2) glial cells in bulbar nerves with filaments and laminar cytoplasm; (3) a 3rd type of cells forms multilayer envelopes in the main cords (MC); also they make contacts with the excretory epithelium. To demonstrate the existence of glial cells, an immunocytochemical and ultrastructural investigation of Ligula intestinalis was undertaken. Intensive S100b-like immunoreaction (IR) was found in the GG and in the MC. IR-varicosities were mostly located asymmetrically on the MC, and no IR was found in neuropiles. Small glial cells were found on the surface of the MC; they have oval nuclei and dense cytoplasm with slim processes going around the neuropile and enclosing neurons. Long junctions are seen between cell processes but with neurons they usually possess juxtaposition contacts. Glial cells lack vesicles or synapse-like structures. Intensive S100b-like-IR has been shown in the CNS of cestodes for the first time. Results from ultrastructural research support the immunocytochemical date.

Parasitology International, 1998

Parasitology Research, 2015

The sensory organs in tegument of two trypanorhynchean species--Nybelinia surmenicola (plerocerco... more The sensory organs in tegument of two trypanorhynchean species--Nybelinia surmenicola (plerocercoid) and adult Parachristianella sp. (Cestoda, Trypanorhyncha)--were studied with the aim of ultrastructural description and a comparative analysis. The Nybelinia surmenicola plerocercoid lacks papillae with sensory cilia on the bothria adhesive surface. We found an unciliated sensory organ within the median bothria fold. This unciliated free nerve ending contains the central electron-dense disc, three dense supporting rings, and broad root. The nerve ending locates in the basal matrix under the tegument. The tegument of N. surmenicola has a number of ultrastructural features which make it significantly different from other Trypanorhyncha: (i) the tegumental cytoplasm has a plicated constitution in a form of high apical and deep basal folds, (ii) numerous layers of the basal matrix are presented in the subtegument, and (iii) the squamiform and bristlelike microtriches N. surmenicola lack the base and the basal plate. In contrast, numerous ciliated and unciliated receptors were found in Parachristianella sp.: six types on the bothria and one type in the strobila tegument. Ultrastructural constitution of sensory organs in the form of ciliated free nerve endings as well as unciliated basal nerve endings of Parachristianella sp. has many common features inside Eucestoda. In comparison with other Trypanorhyncha, all Nybelinia species studied have less quantity of the bothrial sensory organs. This fact may reflect behavioral patterns of Nybelinia as well as phylogenetic position into Trypanorhyncha. Our observations of living animals conventionally demonstrate the ability of N. surmenicola plerocercoids to locomote in forward direction on the Petri dish surface. The participation of the bothrial microtriches in a parasite movement has been discussed.

Journal of limnology

The ultrastructure of the digestive system of tardigrades was already described in some species, ... more The ultrastructure of the digestive system of tardigrades was already described in some species, but it has never been studied in relationship to diet. We performed ultrastructural analyses of the midgut and hindgut of phytophagous Ramazzottius tribulosus and zoophagous Macrobiotus richtersi. In addition, the foregut of R. tribulosus was analyzed. New ultrastructural details have been observed. Among them are: (a) distinct transverse pillar-like structures, lacking in electron-dense and compact cuticle of the buccal tube; (b) a hole or groups of holes sometimes present in the buccal tube; (c) a large cavity within each of the salivary glands where secreted mucus accumulates; and (d) already found in zoophagous Isohypsibius prosostomus, one valve, formed by folds of the pharynx and located at the transition from pharynx to esophagus. In both analyzed species the increase of midgut surface is identified by two orders of folds of the gut wall and by microvilli. In R. tribulosus there a...

Parasitology

The nervous system of young and adult Amphilina foliacea was studied with immunocytochemical, ele... more The nervous system of young and adult Amphilina foliacea was studied with immunocytochemical, electron microscopical and spectrofluorometrical methods. The general neuroanatomy is described in detail. New data on the structure and development of the brain were obtained. The S-HT and GYIRFamide-immunoreactivities occur in separate sets of neurones. The innervation of the reproductive organs is described. The fine structure of 2 types of neurones in the CNS, a sensory neurone, a ' glial' cell type, the neuropile and the synapses are described. The level of 5-HT varies between 0-074 and 0461 /tg/g wet weight. This is the first detailed study of the nervous system of A. foliacea. Earlier data on the structure of the nervous system in A. foliacea published in Russian are introduced into the discussion. The study provides data that can be used when considering the phylogenetic position of Amphilinidea.

Fourteen species of freshwater tardigrades were found in Lake Biwa (Japan). One of them, Pseudobi... more Fourteen species of freshwater tardigrades were found in Lake Biwa (Japan). One of them, Pseudobiotus vladimiri is new for science. It differs from the other species of the genus the sculptured cuticle and the emerging accessory points in the main branch of the claws. Apart P. megalonyx, it differs from the other Pseudobiotus also in the shape of the placoids.

DESCRIPTION The paper deals with the reconstruction of the Parachristianella sp. cerebral ganglio... more DESCRIPTION The paper deals with the reconstruction of the Parachristianella sp. cerebral ganglion. Based on the serial semi thin and ultra thin transverse sections of scolex, a reconstruction of the general structure and fine details of the cerebral ganglion Parachristianella sp. were made. Ganglion consists of two pairs of frontal and lateral lobes and an unpaired central (=median) lobe. Frontal lobes are combined by semiring commissura in the dorsal and ventral pairs. Dou ble lateral lobes are connected with median (=central) and crisscross commissura. Dorsal and ventral nerve rootlets origin from the lateral lobes and innervate the musculature of bothria. Dorsal and ventral rootlets form the back of the scolex sublateral nerves running parallel to the main nerve cord. Four pairs of nerves (tentacles and bulbar) consisting of myelinated giant axons were revealed. Giant axons somata lie in crisscross commissure, as well as in the upper and lower parts of these nerves. Specific ult...

Parasitic worms can survive in the host body for a long time due to their ability to control the ... more Parasitic worms can survive in the host body for a long time due to their ability to control the immune response. Prostaglandins synthesized by parasites form an important class of immunomodulators. The mechanisms underlying immunoregulation of the host body with prostaglandins are poorly studied, and there is no evidence of prostaglandin functioning in cestodes. Prostaglandin E2 (PG E2) is the most important immunomodulator among prostaglandins. The present study investigated distribution of PG E2 in the organism of Diphyllobothrium dendriticum and influence of PG E2 on the cell culture of sticklebacks head kidney leukocytes. D. dendriticum plerocercoids have been withdrawn from Baikal omul. The sections of plerocercoids were incubated with monoclonal antibodies against PG E2 and α-tubulin, than with secondary antibodies. This was followed by examination with the aid of laser scanning confocal microscope. We have analyzed the frequency of leukocyte subsets (granulocyte to lymphocyt...

Acta biologica Hungarica, 2000

The distribution and morphological diversity of the sensory structures on the body surface, probo... more The distribution and morphological diversity of the sensory structures on the body surface, proboscis and caudal cavity of adult Amphilina foliacea have been investigated. Fifteen different types of receptors are described. Along with nonciliated and uniciated receptors bi- and multiciliated receptors have been found for the first time. The zonal distribution of the sensory structures and their coincidence within the same areas of the body surface have been revealed. The concentration of sensory structures at the posterior end may indirectly confirm a hypothesis of the unavailability of developed attachment disk in ancestors of amphilinids.