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Journal ArticleDOI

Seasonal variations in olfactory sensory neurons--fish sensitivity to sex pheromones explained?

24 Oct 2007-Chemical Senses (Oxford University Press)-Vol. 33, Iss: 2, pp 119-123
TL;DR: It is demonstrated that the number of crypt cells in the olfactory epithelium of the crucian carp varies dramatically throughout the year, which may explain previous studies demonstrating a relationship between circulating androgen and Olfactory sensitivity to sex pheromones.
Abstract: Olfactory sensory neurons of vertebrates regenerate throughout the life of the animal. In fishes, crypt cells are a type of olfactory sensory neurons thought to respond to sex pheromones. Here, we demonstrate that the number of crypt cells in the olfactory epithelium of the crucian carp varies dramatically throughout the year. During winter, few crypt cells are observed at any location within the sensory epithelium. In spring, the majority of crypt cells are located deep in the epithelium not yet exposed to the environment. However, during the summer spawning season, crypt cells are positioned at the epithelial surface. These findings may explain previous studies demonstrating a relationship between circulating androgen and olfactory sensitivity to sex pheromones.
Citations
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Journal ArticleDOI
TL;DR: Concentrations and effects of progestins in aquatic systems were mostly detected when analyzed for, and they occurred in the low ng/L range in wastewater and surface water, while reproduction effects occurred at higher levels.

175 citations

Journal ArticleDOI
TL;DR: The integrated approach combining genetic, neuroanatomical, and behavioral methods enables us to elucidate the neural circuit mechanism underlying various olfactory behaviors in adult zebrafish.
Abstract: In fish, amino acids are food-related important olfactory cues to elicit an attractive response. However, the neural circuit underlying this olfactory behavior is not fully elucidated. In the present study, we applied the Tol2 transposon-mediated gene trap method to dissect the zebrafish olfactory system genetically. Four zebrafish lines (SAGFF27A, SAGFF91B, SAGFF179A, and SAGFF228C) were established in which the modified transcription activator Gal4FF was expressed in distinct subsets of olfactory sensory neurons (OSNs). The OSNs in individual lines projected axons to partially overlapping but mostly different glomeruli in the olfactory bulb (OB). In SAGFF27A, Gal4FF was expressed predominantly in microvillous OSNs innervating the lateral glomerular cluster that corresponded to the amino acid-responsive region in the OB. To clarify the olfactory neural pathway mediating the feeding behavior, we genetically expressed tetanus neurotoxin in the Gal4FF lines to block synaptic transmission in distinct populations of glomeruli and examined their behavioral response to amino acids. The attractive response to amino acids was abolished only in SAGFF27A fish carrying the tetanus neurotoxin transgene. These findings clearly demonstrate the functional significance of the microvillous OSNs innervating the lateral glomerular cluster in the amino acid-mediated feeding behavior of zebrafish. Thus, the integrated approach combining genetic, neuroanatomical, and behavioral methods enables us to elucidate the neural circuit mechanism underlying various olfactory behaviors in adult zebrafish.

122 citations


Cites background from "Seasonal variations in olfactory se..."

  • ...In contrast, little is known about the molecular constituents, axonal projection, and function of the crypt cells (11, 12, 19, 20), despite their unique properties such as seasonal variability (21)....

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Journal ArticleDOI
TL;DR: A framework is provided for elucidating the neural circuit computations underlying the odor-driven behaviors in this small, transparent, and genetically amenable vertebrate.
Abstract: The fish olfactory system processes odor signals and mediates behaviors that are crucial for survival such as foraging, courtship and alarm response. Although the upstream olfactory brain areas (olfactory epithelium and olfactory bulb) are well studied, less is known about their target brain areas and the role they play in generating odor-driven behaviors. Here we review a broad range of literature on the anatomy, physiology and behavioral output of the olfactory system and its target areas in a wide range of teleost fish. Additionally, we discuss how applying recent technological advancements to the zebrafish (Danio rerio) could help in understanding the function of these target areas. We hope to provide a framework for elucidating the neural circuit computations underlying the odor-driven behaviors in this small, transparent and genetically amenable vertebrate.

89 citations


Cites background from "Seasonal variations in olfactory se..."

  • ...Their density and depth in the olfactory epithelium was shown to vary depending on the seasons in sexually mature carp (Hamdani el et al., 2008)....

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Journal ArticleDOI
TL;DR: Results provide support for the hypothesis that the first-order olfactory relay station is a substrate for both GnRH and sex steroid modulation, and suggest that changes in receptor levels could be an important mechanism for regulating reproductive, social, and seasonal plasticity in Olfactory perception observed across vertebrates.

66 citations

Journal ArticleDOI
TL;DR: It is reported that TrkA-like immunoreactivity specifically labeled somata, axons, and terminals of zebrafish crypt neurons and reveal a single glomerulus, mdg2 of the dorsomedial group, as targetglomerulus of crypt neurons.
Abstract: Crypt neurons are a third type of olfactory receptor neurons with a highly unusual “one cell type - one receptor” mode of expression, the same receptor being expressed by the entire population of crypt neurons Attempts to identify the target region(s) of crypt neurons have been inconclusive so far We report that TrkA-like immunoreactivity specifically labeled somata, axons, and terminals of zebrafish crypt neurons and reveal a single glomerulus, mdg2 of the dorsomedial group, as target glomerulus of crypt neurons Injection of a fluorescent tracing dye into the mdg2 glomerulus retrogradely labeled mostly crypt neurons, as assessed by quantitative morphometry, whereas no crypt neurons were found after injections in neighboring glomeruli Our data provide strong evidence that crypt neurons converge onto a single glomerulus, and thus form a labeled line consisting of a single sensory cell type, a single olfactory receptor and a single target glomerulus

61 citations

References
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MonographDOI
30 Oct 1931-Copeia

1,131 citations

Journal ArticleDOI
TL;DR: The findings support the hypothesis that olfactory transduction and neural processing in the peripheral Olfactory pathway involve basic mechanisms that are universal across most species in most phyla.
Abstract: ▪ Abstract Olfaction begins with the transduction of the information carried by odor molecules into electrical signals in sensory neurons. The activation of different subsets of sensory neurons to different degrees is the basis for neural encoding and further processing of the odor information by higher centers in the olfactory pathway. Recent evidence has converged on a set of transduction mechanisms, involving G-protein-coupled second-messenger systems, and neural processing mechanisms, involving modules called glomeruli, that appear to be adapted for the requirements of different species. The evidence is highlighted in this review by focusing on studies in selected vertebrates and in insects and crustaceans among invertebrates. The findings support the hypothesis that olfactory transduction and neural processing in the peripheral olfactory pathway involve basic mechanisms that are universal across most species in most phyla.

1,066 citations


"Seasonal variations in olfactory se..." refers background in this paper

  • ...One aspect is the conservation of the olfactory system during evolution ( Hildebrand and Shepherd 1997 )....

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Journal ArticleDOI
TL;DR: The morphological stages of maturation and ageing of this exceptional neuron have been described both at light and electron microscopical levels and the neural elements have been classified as: basal cells proper, globose basal cells, and neurons.
Abstract: The neurogenetic process leading to the formation of primary sensory neurons persists into adult life in the olfactory epithelium of mammals. The morphological stages of maturation and ageing of this exceptional neuron have been described both at light and electron microscopical levels. For descriptive purposes the neural elements have been classified as: (1) basal cells proper, (2) globose basal cells, and (3) neurons. Intermediate stages, however, have been identified. Autoradiographic observations complement the morphological studies and provide a time sequence of the morphological stages leading to the mature neurons. A typical columnar arrangement of the sensory neurons has been described. Furthermore, active and quiescent zones have been recognized in the neuroepithelium. In the active zones the neurogenetic process is vigorous, and the zones are characterized by the presence of immature elements. However, in the quiescent zones there exists a population of mature elements while immature neurons are sparse.

964 citations

Journal ArticleDOI
James E. Schwob1
TL;DR: Cell renewal in the epithelium is directed to replace neurons when they die in normal animals and does so at an accelerated pace after damage to the olfactory nerve, and multiple growth factors are likely to be central in regulating choice points in epitheliopoiesis.
Abstract: The peripheral olfactory system is able to recover after injury, i.e., the olfactory epithelium reconstitutes, the olfactory nerve regenerates, and the olfactory bulb is reinnervated, with a facility that is unique within the mammalian nervous system. Cell renewal in the epithelium is directed to replace neurons when they die in normal animals and does so at an accelerated pace after damage to the olfactory nerve. Neurogenesis persists because neuron-competent progenitor cells, including transit amplifying and immediate neuronal precursors, are maintained within the population of globose basal cells. Notwithstanding events in the neuron-depleted epithelium, the death of both non-neuronal cells and neurons directs multipotent globose basal cell progenitors, to give rise individually to sustentacular cells and horizontal basal cells as well as neurons. Multiple growth factors, including TGF-α, FGF2, BMPs, and TGF-βs, are likely to be central in regulating choice points in epitheliopoiesis. Reinnervation of the bulb is rapid and robust. When the nerve is left undisturbed, i.e., by lesioning the epithelium directly, the projection of the reconstituted epithelium onto the bulb is restored to near-normal with respect to rhinotopy and in the targeting of odorant receptor-defined neuronal classes to small clusters of glomeruli in the bulb. However, at its ultimate level, i.e., the convergence of axons expressing the same odorant receptor onto one or a few glomeruli, specificity is not restored unless a substantial number of fibers of the same type are spared. Rather, odorant receptor-defined subclasses of neurons innervate an excessive number of glomeruli in the rough vicinity of their original glomerular targets. Anat Rec (New Anat) 269:33–49, 2002. © 2002 Wiley-Liss, Inc.

468 citations


"Seasonal variations in olfactory se..." refers background in this paper

  • ...Another aspect is that sensory neurons in the mammalian olfactory epithelium regenerate throughout the life of the animal (Moulton 1974; Graziadei and Graziadei 1979; Schwob 2002 )....

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Journal ArticleDOI
TL;DR: The olfactory organ-unlike most receptor sheet-must be directly exposed to airborne chemicals, but this requirement also mates vulnerability to bacterial and viral invasion, to the mechanical impact of the respiratory airstream, and to the toxic effects of environmental pollutants.
Abstract: The olfactory organ-unlike most receptor sheet-must be directly exposed to airborne chemicals. But this requirement also mates vulnerability to bacterial and viral invasion, to the mechanical impact of the respiratory airstream, and, perhaps, to the toxic effects of environmental pollutants. In fact, rhinitic infections, with accompanying pathological changes in the olfactory epithelium, are common in at least some species of laboratory animals.12*26* 2% 80 Despite this exposure, the olfactory system of most individuals appears to retain its capacity of detecting and recognizing odors throughout life. Does it, therefore, possess special mechanisms for maintaining function in the face of cell loss? If so, what are these mechanisms? And what effect, if any, would they have on olfactory function. I t is true that the number of olfactory receptors is vast (106 in man, 10s in rabbits), so perhaps even extensive attrition need not seriously compromise function. On the other hand, most tissues regenerate or renew at either the biochemical or cellular level or both. The olfactory epithelium may be no exception. If renewal is confined to subcellular biochemical events, the functional consequences could be significant but are likely to be minimal, If, however, receptor renewal or regeneration occurs, the epithelium and primary neurones must undergo extensive reorganization if normal function is to be maintained or restored. In particular, olfactory receptors are not synaptically isolated from the neurones that connect them to the brain (as is the case with auditory, visual, and taste receptors). Thus, if a receptor is to be replaced, the entire axonal connection to the olfactory bulb must also be replaced. There are good reasons for examining this possibility with caution: neurones do not generally regenerate after loss of the cell body. Nevertheless, the olfactory receptors are specialized neurones and may, in this regard, conform more to the behavior of, say, respiratory epithelial cells. Inquiries into the properties of cell populations in a variety of epithelial and other tissues have long depended on concepts such as that of the cell cycle and on techniques such as that of autoradiography. Until recently, however, these aspects of cell biology had not informed work on the olfactory epithelium: there was essentially no discussion of the properties of its constituent cell populations in quantitative and dynamic terms, and there was little apparent awareness of either the criteria necessary for distinguishing between certain types of proliferating cell populations or the importance of these distinctions for an understanding of olfactory function. This earlier literature has been revised in depth by Takagi.52 During the last few years the picture has begun to change. We now have quantitative information concerning proliferating cell populations in the olfactory epithelium, and some understanding of the dynamic properties of this system is beginning to emerge. Perhaps, then, the time is appropriate to take stock of the

231 citations


"Seasonal variations in olfactory se..." refers background in this paper

  • ...Another aspect is that sensory neurons in the mammalian olfactory epithelium regenerate throughout the life of the animal ( Moulton 1974; Graziadei and Graziadei 1979; Schwob 2002)....

    [...]

  • ...In the original publications of Andres (1965), Graziadei et al. (1980), and Moulton (1974) on the mammalian olfactory organs, it was presumed that all types of olfactory sensory neurons undergo a continuous turnover....

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