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Neurogenesis is the process by which new brain cells are formed. This crucial event emerges during embryonic life and proceeds in adulthood, and it could be influenced by environmental pollution. Non-combustion-derived magnetite represents a portion of the coarse particulate matter (PM) contributing to air and water pollution in urban settings. Studies on humans have reported that magnetite and other iron oxides have significant damaging effects at a central level, where these particles accumulate and promote oxidative stress. Similarly, magnetite nanoparticles can cross the placenta and damage the embryo brain during development, but the impact on neurogenesis is still unknown. Furthermore, an abnormal Fe cation concentration in cells and tissues might promote reactive oxygen species (ROS) generation and has been associated with multiple neurodegenerative conditions. In the present study, we used zebrafish as an in vivo system to analyze the specific effects of magnetite on embryonic neurogenesis. First, we characterized magnetite using mineralogical and spectroscopic analyses. Embryos treated with magnetite at sub-lethal concentrations showed a dose–response increase in ROS in the brain, which was accompanied by a massive decrease in antioxidant genes (sod2, cat, gsr, and nrf2). In addition, a higher number of apoptotic cells was observed in embryos treated with magnetite. Next, interestingly, embryos exposed to magnetite displayed a decrease in neural staminal progenitors (nestin, sox2, and pcna markers) and a neuronal marker (elavl3). Finally, we observed significative increases in apoeb (specific microglia marker) and interleukin-1b (il1b), confirming a status of inflammation in the brain embryos treated with magnetite. Our study represents the very first in vivo evidence concerning the effects of magnetite on brain development. [ABSTRACT FROM AUTHOR]

Nitrogen-based fertilizers represent the most common fertilization tools, particularly used in crop food agriculture, despite the low cost-efficiency and the high negative environmental impact. At present, there is still inadequate information available about the effects of urea on human health; nevertheless, previous studies in animals observed that high urea concentration exposure can damage different tissues, including the brain. In several vertebrates, a crucial factor involved in neuronal cell formation is represented by the gas molecule, nitric oxide (NO), derived from the conversion of arginine to citrulline through the enzymatic activity of nitric oxide synthases (NOS). In zebrafish, three different isoforms of the NOS gene are known: nos1, nos2a, and nos2b. In the present study we show that nos1 represents the unique isoform with a stable high expression in the brain and spinal cord during all the embryonic stages of zebrafish development. Then, by using a specific transgenic zebrafish line, Tg(HuC:GFP), to mark neuronal cells, we observed nos1 to be specifically expressed in neurons. Interestingly, we observed that urea exposure at sub-lethal doses affected cell proliferation and the number of nos1-expressing cells, inducing apoptosis. Consistently, brain NO levels were observed to be reduced in urea-treated animals compared to untreated ones. This finding represents the first evidence that urea exposure affects the expression of a key gene involved in neuronal cell formation during embryonic development. [ABSTRACT FROM AUTHOR]

Simple Summary: Fertility, in males and females, is linked to the correct formation of sexual line cells (spermatozoa and oocytes) through a physiological process called meiosis. In all vertebrates, meiosis is orchestrated by different molecular effectors, and among these, we focused our attention on CLASP2, a protein involved in cytoskeleton function. In several animal models, such as mice, flies, or frogs, this protein is known to participate in spermatozoa maturation. However, in fish, nothing was known about the presence of CLASP2 in sexual organs or whether it could have a role in spermatozoa formation. To investigate this point, we used two excellent vertebrate aquatic models: guppy and zebrafish. Our results open a window to knowledge about male sex cell formation effectors in fish. Considering the great affinity between zebrafish and humans, the study of CLASP2 in fish spermatogenesis could uncover a new target of male fertility in humans. Cytoplasmic linker-associated protein-2 (CLASP2) is a member of the CLIP-associating proteins (CLASPs) family involved in the structure and function of microtubules and Golgi apparatus. Several studies performed using different mammalian and non-mammalian model organisms reported that CLASP2 controls microtubule dynamics and the organization of microtubule networks. In Drosophila and mice, an important role of CLASP2 during the development of germ cell lines has been uncovered. However, no study has clearly defined its role during fish germ cell differentiation. In the present study, we used two excellent aquatic animal models among teleost fish: zebrafish (Danio rerio) and guppy (Poecilia reticulata). Using qPCR, we found that the clasp2 transcript level is significantly high in the testis of both fish. Then, by in situ hybridization, we localized the clasp2 transcript in the spermatozoa of zebrafish and the spermatozeugmata of guppy. Our data suggest a potential role for this gene in the last stage of spermiogenesis in fish. [ABSTRACT FROM AUTHOR]

In vertebrates, neurotrophins and their receptors play a fundamental role in the central and peripheral nervous systems. Several studies reported that each neurotrophin/receptor signalling pathway can perform various functions during axon development, neuronal growth, and plasticity. Previous investigations in some fish species have identified neurotrophins and their receptors in the spinal cord under physiological conditions and after injuries, highlighting their potential role during regeneration. In our study, for the first time, we used an excellent animal model, the zebrafish (Danio rerio), to compare the mRNA localization patterns of neurotrophins and receptors in the spinal cord. We quantified the levels of mRNA using qPCR, and identified the transcription pattern of each neurotrophin/receptor pathway via in situ hybridization. Our data show that ngf/trka are the most transcribed members in the adult zebrafish spinal cord. [ABSTRACT FROM AUTHOR]

The germline is a key feature of sexual animals and the ways in which it separates from the soma differ widely across Metazoa. However, at least at some point during germline differentiation, some cytoplasmic supramolecular structures (collectively called germ plasm-related structures) are present and involved in its specification and/or differentiation. The factors involved in the assembly of these granular structures are various and non-ubiquitous among animals, even if some functional patterns and the presence of certain domains appear to be shared among some. For instance, the LOTUS domain is shared by Oskar, the Holometabola germ plasm master regulator, and some Tudor-family proteins assessed as being involved in the proper assembly of germ granules of different animals. Here, we looked for the presence of LOTUS-containing proteins in the transcriptome of Ruditapes philippinarum (Bivalvia). Such species is of particular interest because it displays annual renewal of gonads, sided by the renewal of germline differentiation pathways. Moreover, previous works have identified in its early germ cells cytoplasmic granules containing germline determinants. We selected the orthologue of TDRD7 as a candidate involved in the early steps of germline differentiation through bioinformatic predictions and immunohistological patterning (immunohistochemistry and immunofluorescence). We observed the expression of the protein in putative precursors of germline cells, upstream to the germline marker Vasa. This, added to the fact that orthologues of this protein are involved in the assembly of germ granules in mouse, zebrafish, and fly, makes it a worthy study unit for investigations on the formation of such structures in bivalves. [ABSTRACT FROM AUTHOR]

Heteroplasmy is the presence of more than one type of mitochondrial genome within an individual, a condition commonly reported as unfavorable and affecting mitonuclear interactions. So far, no study has investigated heteroplasmy at protein level, and whether it occurs within tissues, cells, or even organelles. The only known evolutionarily stable and natural heteroplasmic system in Metazoa is the Doubly Uniparental Inheritance (DUI)—reported so far in ∼100 bivalve species—in which two mitochondrial lineages are present: one transmitted through eggs (F-type) and the other through sperm (M-type). Because of such segregation, mitochondrial oxidative phosphorylation proteins reach a high amino acid sequence divergence (up to 52%) between the two lineages in the same species. Natural heteroplasmy coupled with high sequence divergence between F- and M-type proteins provides a unique opportunity to study their expression and assess the level and extent of heteroplasmy. Here, for the first time, we immunolocalized F- and M-type variants of three mitochondrially-encoded proteins in the DUI species Ruditapes philippinarum , in germline and somatic tissues at different developmental stages. We found heteroplasmy at organelle level in undifferentiated germ cells of both sexes, and in male soma, whereas gametes were homoplasmic: eggs for the F-type and sperm for the M-type. Thus, during gametogenesis, only the sex-specific mitochondrial variant is maintained, likely due to a process of meiotic drive. We examine the implications of our results for DUI proposing a revised model, and we discuss interactions of mitochondria with germ plasm and their role in germline development. Molecular and phylogenetic evidence suggests that DUI evolved from the common Strictly Maternal Inheritance, so the two systems likely share the same underlying molecular mechanism, making DUI a useful system for studying mitochondrial biology. [ABSTRACT FROM AUTHOR]

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Reconstitution and renewal of tissues are key topics in developmental biology. In this brief work, we analyzed the wintry spent phase of the reproductive cycle in the Manila clam Ruditapes philippinarum (Bivalvia, Veneridae) in order to study the gonad rebuilding that in this species occurs at the beginning of the warmer months. We labeled VASA homolog protein-a germ cell marker-and compared the histological observations of the spent phase with those of the previously analyzed gametogenic phase. In R. philippinarum, during the reproductive season, most of the body mass is represented by sack-like structures (acini) full of developing gametes. In that period, VASA-stained cells are present at the basal pole of the gut epithelium, in the connective tissue, and around the acini. We here show that during the spent phase large portions of the intestine lack such cell type, except for some areas showing a few faintly VASA-stained cells. Cells with similar nuclear morphology are present among loosely organized cells of connective tissue, sometimes as single units, sometimes in small groups, rarely partially organized in primordial gonadic structures. These observations match the findings of RNA-targeting studies that during the spent phase identified the source of bivalve germ cells within the connective tissue in the form of quiescent units and add new information on the possible maintenance of VASA-stained, multipotent cells among the batiprismatic cells of the intestine during the whole life span of these bivalves. [ABSTRACT FROM AUTHOR]

Olfactory crypt neurons have been observed in several bony fishes and chondrichtyans. Although their morphology is uniform in all fish, very few is known about their antigenic properties, usually studied in zebrafish, but quite overlooked in other species. We tested in Poecilia reticulata (guppy) the two antibodies recognized to mark zebrafish crypt cells: while anti-S100 showed an immunohistochemical pattern comparable to what reported in zebrafish, anti-TrkA gave no signal. Western blot analysis revealed that S100-antiserum bound an antigen of expected weight, probably belonging to the S100 family. On the contrary, anti-TrkA detected more bands, but the protein/s might be too much diffused and/or diluted in the tissue to be detected with immunohistochemistry. Because of the high level of conservation in the Trk family proteins of the kinase domain, on which anti-TrkA was produced, we also tested anti-TrkB to exclude cross reactivity. Immunohistochemistry and Western blot confirmed that anti-TrkB displayed high specificity to its target and a different staining pattern compared to anti-TrkA, but, as anti-TrkA, it did not label crypt neurons. Finally, we documented that calretinin, a known marker of zebrafish ciliated and microvillous olfactory cells, in the guppy is expressed also by a subpopulation of S100-positive crypt neurons. These results reveal differences in antigen expression between zebrafish and guppy crypt cells. Together with the already known species-specific projections to the olfactory bulb and a heterogeneous panel of odorants, our findings support the possibility that crypt cells are functionally less uniform as supposed. [ABSTRACT FROM AUTHOR]

Germ line segregation can occur during embryogenesis or after embryogenesis completion, with multipotent cells able to give rise to both germ and somatic cells in the developing juvenile or even in adulthood. These undifferentiated cells, in some animals, are self-renewing stem cells. In all these cell lineages, the same set of genes, among which vasa, appears to be expressed. We traced VASA expression during the peculiar gonad rebuilding of bivalves to verify its presence from undifferentiated germ cells to mature gametes in an animal taxon in which the mechanism of germ line establishment is still under investigation. We utilized antibodies produced against VASPH, VASA homolog of Ruditapes philippinarum (Subclass Heterodonta), to compare the known expression pattern of R. philippinarum to two species of the Subclass Pteriomorphia, Anadara kagoshimensis and Crassostrea gigas, and another species of the Subclass Heterodonta, Mya arenaria. The immunohistological data obtained support a conserved mechanism of proliferation of 'primordial stem cells' among the simple columnar epithelium of the gut, as well as in the connective tissue, contributing to the seasonal gonad reconstitution. Given the taxonomic separation of the analyzed species, we suggest that the process could be shared in bivalve molluscs. The presence of germ cell precursors in the gut epithelium appears to be a feature in common with model organisms, such as mouse, fruit fly, and human. Thus, the comparative study of germ line establishment can add details on bivalve development, but can also help to clarify the role that VASA plays during germ cell specification. [ABSTRACT FROM AUTHOR]

The olfactory and vomeronasal systems of vertebrates are characterised by neurogenesis occurring throughout life. The regenerative ability of olfactory receptor neurons relies on specific glial cells, the olfactory and vomeronasal axon-surrounding cells. Numerous studies have examined mammalian olfactory ensheathing cells which are considered potential candidates for spinal cord injury repair using cell-based therapy. With regard to non-mammalian vertebrates, limited information is available on these glial cells in fish, and there is no information on them in terrestrial anamniotes, the amphibians. In the present research, we studied the immunocytochemical characteristics of axon-surrounding cells in Ambystoma mexicanum. Urodeles have relatively simple olfactory and vomeronasal systems, and represent a good model for studying ensheathing cells in extant representatives of basal tetrapods. Sections from the decalcified heads of A. mexicanum were immunocytochemically processed for the detection of proteins used in research on mammalian olfactory-ensheathing cells. S100, GFAP and NCAM were clearly observed. p75NTR, Gal-1 and PSA-NCAM showed weak staining. No vimentin immunopositivity was observed. The corresponding areas of the olfactory and vomeronasal pathways displayed the same staining characteristics, with the exception of Gal-1, p75NTR and PSA-NCAM in the mucosae. The degree of marker expression was not uniform throughout the sensory pathways. In contrast to fish, both olfactory and vomeronasal nerves displayed uniform staining intensity. This study showed that some markers for mammalian and fish-ensheathing glia are also applicable in urodeles. The olfactory systems of vertebrates show similarities, and also clear dissimilarities. Further investigations are required to ascertain the functional significance of these regional and interspecific differences. [ABSTRACT FROM AUTHOR]

The effects of uremia on human olfactory functions have been clinically evaluated in various studies, even if to date it is not completely clarified which uremic toxins mediate these processes. Surprisingly, the role of the main molecule involved in uremia, urea indeed, has not been adequately investigated as other possible molecules may also be involved in uremic anosmia. The effects of urea on the olfaction have been evaluated in some clinical studies, but this is the first attempt to determine a direct action of urea on the olfactory epithelium of a vertebrate. Danio rerio adults were exposed to urea in different experiments to assess the effects on olfactory sensitivity and signal transduction. The analysis of the swimming speed has been used to evaluate the response to hypoxanthine 3-N-oxide (H3NO), a molecule that is known to elicit an olfactory-mediated alarm reaction in D. rerio. The presence and distribution of the G protein alpha subunit coupled to the olfactory receptors (Gαolf) has been immunohistochemically investigated in the olfactory epithelium of control and urea-exposed D. rerio. Our findings showed that urea alters the response to H3NO of D. rerio with a quite rapid and reversible effect that appears to be independent from a mere interference of urea on the receptor-ligand binding. The Gαolf protein resulted increases after urea treatment, suggesting an effect of urea on its expression or degradation. [ABSTRACT FROM AUTHOR]

Chronic renal disease is known to alter olfactory function, but the specific changes induced in olfactory organs during this process remain unclear. Of the uraemic toxins generated during renal disease, high levels of urea are known to induce hyposmic conditions. In this study, the effects of environmental exposure to elevated concentrations of urea (7, 13.5 and 20 g L-1) on the sensory mucosa of zebrafish in acute toxicity and chronic toxicity tests were described. It was observed that lamellae maintained structural integrity and epithelial thickness was slightly reduced, but only following exposure to the highest concentrations of urea. Panneuronal labelling with anti-Hu revealed a negative correlation with levels of urea, leading to investigation of whether distinct neuronal subtypes were equally sensitive. Using densitometric analysis of immunolabelled tissues, numbers of Gα olf-, TRPC2- and TrkA-expressing cells were compared, representing ciliated, microvillous and crypt neurons, respectively. The three neuronal subpopulations responded differently to increasing levels of urea. In particular, crypt cells were more severely affected than the other cell types, and Gα olf-immunoreactivity was found to increase when fish were exposed to low doses of urea. It can be concluded that exposure to moderate levels of urea leads to sensory toxicity directly affecting olfactory organs, in accordance with the functional olfactometric measurements previously reported in the literature. [ABSTRACT FROM AUTHOR]

Continuous lifelong neurogenesis is typical of the vertebrate olfactory system. The regenerative ability of olfactory receptor neurons is dependent on the glial cell type specific to the olfactory pathway, designated 'olfactory ensheathing cells'. Several studies to date have focused on mammalian olfactory ensheathing cells, owing to their potential roles in cell-based therapy for spinal cord injury repair. However, limited information is available regarding this glial cell type in non-mammalian vertebrates, particularly anamniotes. In the current immunocytochemical study, we analysed the features of olfactory ensheathing cells in the zebrafish, Danio rerio. Fish provide a good model for studying glial cells associated with the olfactory pathway of non-mammalian vertebrates. In particular, zebrafish has numerous valuable features that enable its use as a prime model organism for genetic, neurobiological and developmental studies, as well as toxicology and genomics research. Paraffin sections from decalcified heads of zebrafish were processed immunocytochemically to detect proteins used in the research on mammalian olfactory ensheathing cells, including glial fibrillary acid protein ( GFAP), S100, neural cell adhesion molecule ( NCAM), polysialylated NCAM ( PSA- NCAM), vimentin (VIM), p75 NTR and galactin (Gal)-1. Notably, GFAP, S100, NCAM and Gal-1 were clearly observed, whereas no vimentin staining was detected. Weak immunostaining for PSA- NCAM and p75 NTR was evident. Moreover the degree of marker expression was not uniform in various tracts of the zebrafish olfactory pathway. The immunostaining patterns of the zebrafish olfactory system are distinct from those of other fish to some extent, suggesting interspecific differences. We also showed that the olfactory pathway of zebrafish expresses markers of mammalian olfactory ensheathing cells. The olfactory systems of vertebrates have similarities but there are also marked variations between them. The issue of whether regional and interspecific differences in immunostaining patterns of olfactory pathway markers have functional significance requires further investigation. [ABSTRACT FROM AUTHOR]

In the olfactory system of vertebrates, neurogenesis occurs throughout life. The regenerating activities of the olfactory receptor neurons are connected to particular glial cells in the olfactory pathway: the olfactory ensheathing cells. A considerable number of studies are available in literature regarding mammalian olfactory ensheathing cells; this is due to their potential role in cell-based therapy for spinal cord injury repair. But very little is known about these cells in non-mammalian vertebrates. In this study we examined the immunocytochemical characteristics of the olfactory ensheathing cells in fish, which provide a good model for the study of glial cells in the olfactory pathway of non-mammalian vertebrates. Paraffin sections from decalcified heads of Poecilia reticulata (microsmatic fish) and Carassius auratus (macrosmatic fish) were processed to immunocytochemically detect ensheathing cell markers used in research on mammals: GFAP, S100, NCAM, PSA-NCAM, vimentin, p75NTR and galectin-1. GFAP, S100 and NCAM were clearly detected in both fish, though the intracranial tract of the primary olfactory pathway of Carassius appears more S100 stained than the extracranial tract. P75NTR staining is more evident in Poecilia, PSA-NCAM positivity in Carassius. A slight vimentin immunostaining was detected only in Carassius. No galectin-1 staining appeared in the olfactory pathways of either fish. This study shows that some markers for mammalian olfactory ensheathing cells also stain the olfactory pathway in fish. Immunocytochemical staining differs in the two fish under examination, even along the various tracts of the olfactory pathway in the same species. [ABSTRACT FROM AUTHOR]

Crypt cells are one of three types of olfactory sensory neuron, differing from ciliated and microvillar cells in shape, localization and number, and found only in fish. Although crypt cells are morphologically well characterized, their function remains unclear. They were hypothesized to be involved in reproductive behaviours by detecting sex pheromones, but electrophysiological investigations revealed sensitivity to only amino acids. However, the number of crypt cells in adult guppies is not the same in the two sexes. In this study, we compared the size of the crypt cell population in juvenile guppies during the first 90 days after birth. The purpose of our study was to clarify whether a correlation exists between sex and the number of these olfactory neurons. The data show that guppies reach adult crypt cell density when they become sexually mature. Despite a constant increment in volume during development of the olfactory organ, the minimum density of crypt neurons occurs at ∼45days. Moreover, in the early weeks, the density of crypt neurons is greater in males than in females because in females the total number of cells decreases significantly after just 7 days. In adults, however, crypt neurons are found in higher density in females than in males. These findings suggest that the number of crypt cells is sex specific, with independent developmental dynamics between males and females. A role in pheromone detection could explain such a difference, but the early appearance of crypt cells in the first days of life is suggestive of other, not sexually related, functions. [ABSTRACT FROM AUTHOR]

A study of the peripheral olfactory organ, with special attention to the olfactory epithelium, has been carried out in the guppy ( Poecilia reticulata). Guppy is well known to have a vision-based sexual behavior. The olfactory chamber caudally opens directly in an accessory nasal sac, which is bent medially and gives rise to two recesses that can be considered secondary accessory nasal sacs, antero-medial and postero-medial, respectively. The sensory epithelium, which lines only the medial wall of the nasal cavity, is basically flat rising in a very low lamella only in the posterior part. The olfactory receptors are not evenly distributed in the olfactory mucosa, but aggregate in shallow folds separated by epithelial cells with evident microridges. Ciliated olfactory sensory neurons and microvillous olfactory sensory neurons are clearly identified by transmission electron microscopy (TEM). Scarce crypt olfactory neurons are found throughout the sensory folds. The nasal sacs indicates the capacity to regulate the flow of odorant molecules over the sensory epithelium, possibly through a pump-like mechanism associated with gill ventilation. The organization of the olfactory organ in guppy is simple and reminds what is found in early posthatching stages of fish which at the adult state have a well developed olfactory organ. This simple organization supports the idea that the guppy rely on olfaction less than other fish species provided with more extended olfactory receptorial surface. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The distribution of the intermediate filament molecular markers, glial fibrillary acidic protein (GFAP) and vimentin, has been studied in the central nervous system (CNS) of the soft-shell turtle ( Trionyx sinensis) with immunoperoxidase histochemistry. GFAP immunohistochemistry pointed out the presence of different astroglial cell types. The brain pattern consists of ependymal radial glia whose cell bodies are located in the ependymal layer throughout the brain ventricular system. In the spinal cord, the ependyma is immunonegative, whereas positive radial astrocyte cell bodies are displaced from the ependyma into the periependymal position. Star-shaped astrocytes are observed only in the posterior intumescence of the spinal cord. The different regions of the CNS show a different intensity in GFAP immunostaining even in the same cellular type. Vimentin-immunoreactive structures are absent in the brain and spinal cord. The present study reports an heterogeneous feature of the astroglial pattern in the spinal cord compared to the brain which shows an ancestral condition. [ABSTRACT FROM AUTHOR]

The distribution of intermediate filament molecular markers, glial fibrillary acidic protein (GFAP) and vimentin, has been studied in the central nervous system (CNS) of the adult leopard gecko, Eublepharis macularius. This immunohistochemical study points out the presence of different astroglial cell types. The main pattern is constituted by ependymal radial glia, which have their cell bodies located in the ependymal layer throughout the brain ventricular system. Radial glia proper or radial astrocytes show their cell bodies displaced from the ependymal layer into a periependymal zone and are observed only in the spinal cord. Star-shaped astrocytes are scarce. They are detected in the ventral and lateral regions of the diencephalon and mesencephalon, in the superficial layer of the optic tectum, in the ventral medulla oblongata, and in the ventral and lateral spinal cord. In the different regions of the CNS, the staining intensity appears not to be identical even in the same cellular type. The results reported in the present study show an heterogeneous feature of the astroglial pattern in E. macularius. [ABSTRACT FROM AUTHOR]

To investigate the presence of defined carbohydrate moieties on the cell surface of the olfactory and vomeronasal receptor cells and the projections of the latter into the olfactory bulbs, a lectin binding study was performed on the olfactory system of the lizards: Lacerta viridis and Podarcis sicula. Both lizards showed a high lectin binding for N-acetyl-glucosamine in the sensory neurons. The lectin binding patterns in Lacerta indicated that the main olfactory system possessed a moderate density of N-acetyl-galactosamine residues and detectable levels of galactose ones. The vomeronasal system on the other hand contained a high density of N-acetyl-galactosamine moieties and a moderate density of glucosamine ones. In Podarcis the main olfactory system and vomeronasal organ contained respectively detectable and moderate levels of galactose residues. The expression of specific glycoconjugates may be associated with outgrowth, guidance and fasciculation of olfactory and vomeronasal axons. [ABSTRACT FROM AUTHOR]

AbstractFranceschini, V. Lazzari, M. and Ciani, F. 2000. Cell surface glycoconjugates in the olfactory system of lungfish Protopterus annectens Owen. — Acta Zoologica (Stockholm) 81: 131–137 Lectin binding was performed on the olfactory system of lungfish Protopterus annectens to identify specific glycoconjugates on the cell surface of olfactory receptor cells. The lectin histochemical patterns and the Western blot analysis indicate that the receptor cells of the olfactory mucosa are characterized by high density of α-N-acetyl-d-galactosamine residues on the saccharidic chains of the surface glycoproteins. Other lectins display a regional pattern between the regions of the olfactory bulbs. This different histochemical lectin pattern might be due to a different regional segregation of the olfactory projections. On the other hand it could allow the identification of an area corresponding to the accessory olfactory bulb of terrestrial vertebrates in the ventrolateral region of Protopterus olfactory bulb. The presence in the dipnoan olfactory system of a vomeronasal organ homologous to the organ in amphibians is discussed. Moreover, the selective lectin binding on the surface of primary olfactory neurones suggests that specific cell surface glycoproteins may have a role in the axonal growth due to the continuous cycle of proliferation and the death of olfactory receptor cells. [ABSTRACT FROM AUTHOR]

We used immunodeficient mice, whose dorsomedial olfactory region was permanently damaged by dichlobenil inoculation, to test the neuroregenerative properties of transplanted human adipose tissue-derived stem cells after 30 and 60 days. Analysis of polymerase chain reaction bands revealed that stem cells preferentially engrafted in the lesioned olfactory epithelium compared with undamaged mucosa of untreated transplanted mice. Although basal cell proliferation in untransplanted lesioned mice did not give rise to neuronal cells in the olfactory mucosa, we observed clusters of differentiating olfactory cells in transplanted mice. After 30 days, and even more at 60 days, epithelial thickness was partially recovered to normal values, as also the immunohistochemical properties. Functional reactivity to odorant stimulation was also confirmed through electro-olfactogram recording in the dorsomedial epithelium. Furthermore, we demonstrated that engrafted stem cells fused with mouse cells in the olfactory organ, even if heterokaryons detected were too rare to hypothesize they directly repopulated the lesioned epithelium. The data reported prove that the migrating transplanted stem cells were able to induce a neuroregenerative process in a specific lesioned sensory area, enforcing the perspective that they could become an available tool for stem cell therapy. [ABSTRACT FROM AUTHOR]