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J Strotmann

Publications and source records attributed to J Strotmann.

At least 37 records · Page 2Linked to original sources
PubMed1997

Olfactory receptor gene expression.

Recognition and discrimination of odorous molecules are determined by heptahelical G-protein-coupled receptor proteins localized primarily in the ciliary membrane of olfactory sensory neurons. The discovery of a large multigene family encoding odorant receptors allows us to approach various facets concerning the molecular basis of olfactory chemospecificity, ranging from chromosomal localization and control of expression of olfactory receptor genes to temporal and spatial expression patterns of various receptor types in the nasal neuroepithelium. The target-independent onset of receptor expression and its topographical organization suggest a precommited functional identity of olfactory neurons.

Journal Article↗
PubMed1997

Subfamily of olfactory receptors characterized by unique structural features and expression patterns.

The complex chemospecificity of the olfactory system is probably due to the large family of short-looped, heptahelical receptor proteins expressed in neurons widely distributed throughout one of the several zones within the nasal neuroepithelium. In this study, a subfamily of olfactory receptors has been identified that is characterized by distinct structural features as well as a unique expression pattern. Members of this receptor family are found in mammals, such as rodents and opossum, but not in lower vertebrates. All identified subtypes comprise an extended third extracellular loop that exhibits amphiphilic properties and contains numerous charged amino acids in conserved positions. Olfactory sensory neurons expressing these receptor types are segregated in small clusters on the tip of central turbinates, thus representing a novel pattern of expression for olfactory receptors. In mouse, genes encoding the new subfamily of receptors were found to be harbored within a small contiguous segment of genomic DNA. Based on species specificity as well as the unique structural properties and expression pattern, it is conceivable that the novel receptor subfamily may serve a special function in the olfactory system of mammals.

Amino Acid Sequence↗
PubMed1996

Molecular genetics of mammalian olfaction.

Olfaction plays a crucial role in the survival of most animal species; it is remarkable in its ability to recognize and discriminate numerous airborne molecules, yet is one of the least understood senses. The advent of molecular genetic approaches has greatly contributed to disclosing some of the mysteries in olfaction. The identification of olfactory-specific proteins, the discovery of the large receptor gene family, and the first insight into the mechanisms governing chemosensory gene expression hold great promise for an eventually detailed understanding of a sensory system that was previously considered as hardly accessible for research at the molecular level.

Animals↗
PubMed1996

Laminar segregation of odorant receptor expression in the olfactory epithelium.

The laminar segregation of sensory neurons expressing a distinct receptor type was determined in tissue sections through the olfactory epithelium by in situ hybridization employing receptor-specific probes. Reactive cells were restricted to the mid-zone of the epithelium, the location of mature neurons. Detailed analyses revealed that neurons expressing a distinct receptor type were distributed in a characteristic manner throughout the layers of the neuronal zone, i.e. they were preferentially located in a particular laminar zone of the epithelium. Cells expressing different receptor types displayed different distribution patterns. In addition, sets of several reactive neurons within the same laminar zone were found to be arranged in an orderly fashion and were positioned at well-defined intervals. These results indicate that the localization of sensory neurons expressing a distinct receptor type is under stringent control leading to characteristic expression patterns.

Animals↗
PubMed1995

Receptor expression in olfactory neurons during rat development: in situ hybridization studies.

In situ hybridization approaches have been employed to explore the onset and time course of odorant receptor expression during the prenatal development of rats. The critical phase for the maturation of the olfactory system from embryonic day (E) 12 to E18 was analysed. The onset of expression of four receptor genes (OR5, OR14, OR37 and OR124) was found between day E12 and E14. In the early phase of development (E14) a distinct receptor subtype was expressed only in a few hundred neurons; the number increased about two-' to three-fold within a 2 day interval. From the very beginning, spatial segregation of receptor subtypes in distinct expression zones was observed.

Animals↗
PubMed1995

Topographic patterns of odorant receptor expression in mammals: a comparative study.

In a comparative study, molecular probes for various odorant receptor subtypes were employed in in situ hybridization experiments on tissue sections through the nose from different mammalian species. OR37 reactive neurons were found exclusively in the rodent species, where they were clustered in very similar position within the nasal cavities; an OR37-related receptor subtype was not detectable in the rabbit. All other subtypes tested, hybridized across species borders to neurons that were distributed within the distinct zones of the olfactory epithelium. Most receptor types were found in the same zone in all species; however, a few subtypes which are expressed in the medial zone in rat were found in the dorsal zone in guinea pig.

Animals↗
PubMed1995

Two classes of olfactory receptors in Xenopus laevis.

Xenopus laevis possess a gene repertoire encoding two distinct classes of olfactory receptors: one class related to receptors of fish and one class similar to receptors of mammals. Sequence comparison indicates that the fish-like receptors represent closely related members of only two subfamilies, whereas mammalian-like receptors are more distantly related, most of them representing a different subfamily. The fish-like receptor genes are exclusively expressed in the lateral diverticulum of the frog's nose, specialized for detecting water-soluble odorants, whereas mammalian-like receptors are expressed in sensory neurons of the main diverticulum, responsible for the reception of volatile odors.

Amino Acid Sequence↗
PubMed1994

Probing olfactory receptors with sequence-specific antibodies.

Molecular cloning has revealed the structure of several putative odorant receptors. Chemically synthesized peptides, that correspond to a predicted extracellular domain of the encoded proteins, were employed to generate receptor-specific antibodies. Immunohistological approaches as well as Western-blot analysis confirmed the specificity of the antipeptide sera. Furthermore, deglycosylation experiments explained the observed discrepancy between the molecular mass of odorant receptors, as determined by SDS/PAGE and Western-blot analysis of ciliary proteins (M(r) 50,000), and the predicted protein size based on the deduced primary structure from cloned receptor genes (M(r) 30,000-35,000). Receptor proteins become phosphorylated upon odorant stimulation of olfactory cilia preparations; this was demonstrated by immunoprecipitation experiments employing the sequence-directed, receptor-specific antibodies. Functional assays revealed that the receptor-specific antibodies significantly attenuate second messenger signalling elicited by inositol 1,4,5-trisphosphate-inducing odorants, whereas activation of the cAMP cascade by appropriate odorants was not affected. These observation indicate that the sequence-specific antibodies not only recognize odorant receptors, but also discriminate between receptor subtypes coupling to different second-messenger pathways.

Amino Acid Sequence↗
PubMed1994

Rostro-caudal patterning of receptor-expressing olfactory neurones in the rat nasal cavity.

The rostro-caudal extent of odorant receptor expression zones in the rat olfactory epithelium was analysed by means of in situ hybridization. Three broad non-overlapping zones were identified that extended along almost the entire anterior-posterior axis; each zone was composed of several separate bands running anterior to posterior throughout the olfactory epithelium. Super-imposed onto these broad zones was the expression area of a particular receptor subtype (OR37); it was restricted to a small region of the epithelial sheet with a high density of reactive neurones in the centre and declining numbers towards the periphery of the region. A quantitative evaluation of the reactive cells revealed that, despite their different distribution patterns, all receptor subtypes were expressed in an equal number of neurones.

Animals↗
PubMed1994

Olfactory neurones expressing distinct odorant receptor subtypes are spatially segregated in the nasal neuroepithelium.

In situ hybridization techniques have been employed to explore the olfactory epithelium of the rat for the distribution of odorant receptor gene transcripts. We demonstrate that olfactory neurone subpopulations expressing distinct receptor subtypes are spatially segregated within the olfactory epithelium. A compartmentalization of the neuroepithelium into distinct expression zone is apparent, cells expressing a specific receptor are randomly distributed within a given zone. Structurally related receptor subtypes share a common distribution pattern.

Animals↗
PubMed1993

Cloning and expression of odorant receptors.

Myriads of odorous molecules that vary widely in structure are nevertheless readily detected and discriminated by the sense of smell, but how this is achieved by the olfactory system has been a long-standing puzzle. Several different models have been proposed, and previous observations indicate that the recognition sites for odorous molecules could be G-protein-coupled receptor proteins, an idea supported by the discovery of a new gene family that probably encodes a diversity of odorant receptors. Here we report the identification of new members of the gene family encoding putative odorant receptors and demonstrate that they are indeed transcribed in olfactory receptor neurons. Furthermore, the receptor-encoding complementary DNA is expressed in non-neuronal surrogate cells, which generate second messenger responses upon stimulation with appropriate odorants, indicating that the receptors recognize odorants and couple to G proteins of the host cells.

Amino Acid Sequence↗
PubMed1993

Expression of a mucociliary-specific epitope in human olfactory epithelium.

An olfactory ciliary-specific epitope was localized immunohistochemically in the mucociliary complex of human olfactory epithelium of 12 subjects ranging in age from 16 weeks of gestation to 85 years, including 3 with Alzheimer's disease. Immunoreactivity for olfactory marker protein (OMP) was used to identify olfactory epithelium; OMP immunoreactivity in olfactory receptor neurons in a 16-week old fetus is the earliest time point at which OMP expression has been detected in human gestation. The results suggest a close coupling between the expression of ciliary molecules associated with odorant transduction and the functional maturation of olfactory receptor neurons.

Adult↗
PubMed1993

Generation of monoclonal antibodies detecting specific epitopes in locust antennae.

1. Following a tissue-specific screening paradigm, monoclonal antibodies have been generated that interact with distinct subpopulations of cells in locust antennae. 2. Antigens were identified as high molecular weight components. 3. Immunoreactivity was not detectable during embryonic development, but rapidly appeared within a few hours of hatching. 4. The time course of antigen expression in antennal cells could be followed in situ as well as in vitro. 5. Expression of monoclonal antibody B14/6D2-like immunoreactivity was prevented by blocking protein synthesis with cycloheximide.

Animals↗
PubMed1993

Towards an identification of odorant receptors.

The molecular nature and diversity of receptive sites for odorous molecules is a central unanswered issue in olfaction. Based on the enormous resolving power of the olfactory system, which enables the stereospecific discrimination of numerous compounds at low concentrations specific receptor proteins have been proposed. Due to the central role of G-proteins in olfactory signalling it has been predicted that odorant receptors might be members of the superfamily of receptor proteins with seven transmembrane domains. Upon application of degenerated oligonucleotides and the PCR-technology a number of putative odorant receptors have been cloned and sequenced. In situ hybridisation studies using receptor-specific probes have been performed and olfactory neurons specifically expressing a particular receptor subtype are topologically identified in the nasal epithelium of rats. Clones of interest are now being expressed in heterologous systems in order to demonstrate functional activity of these putative receptor proteins and to match defined odorants to identified receptors.

Amino Acid Sequence↗
PubMed1992

Odor-induced phosphorylation of olfactory cilia proteins.

Stimulation of isolated rat olfactory cilia in the presence of [gamma-32P]ATP leads to a significantly enhanced incorporation of [32P]phosphate. Depending on the type of odorants applied, the induced phosphorylation is completely blocked by specific inhibitors of either protein kinase A or protein kinase C. Time-course experiments indicate that the odor-induced modification of ciliary proteins is transient; the intensity of labeling decayed over time (1-10 sec). Separation of ciliary proteins by SDS/polyacrylamide gel electrophoresis followed by autoradiography demonstrated that upon stimulation with lilial, a single polypeptide (50,000 Da) was phosphorylated; the size of the modified protein is in line with the hypothesis that odorant receptors are phosphorylated subsequent to activation by specific odors.

Animals↗
PubMed1992

Expression of odorant receptors in spatially restricted subsets of chemosensory neurones.

From a rat olfactory library a cDNA clone (OR37) which is supposed to encode an odorant receptor protein has been isolated and characterized. Specific antisense RNA and in situ hybridization techniques have been employed to monitor the olfactory epithelium for the distribution of olfactory neurones expressing the OR37-gene. The OR37-transcripts were detected only in a subset of receptor cells segregated in two restricted areas of the olfactory epithelium. The clusters of reactive cells appear symmetrically in both nasal cavities. Within a reactive region only a subset of the cells expressed the receptor. The segregation of neurones expressing a distinct receptor supports the notion that a spatial component may be involved in coding odour quality.

Amino Acid Sequence↗
PubMed1991

Generation of monoclonal antibodies detecting specific epitopes in olfactory and respiratory epithelia.

Two panels of monoclonal antibodies have been generated, each panel having a distinct specificity for antigens located in the ciliary zone of either the olfactory or respiratory epithelium of rats. Tissue specificity was confirmed in enzyme-linked immunosorbent assays on membrane fractions from various tissues. During ontogeny, the expression of olfactory-specific antigens preceeds that of respiratory-specific antigens; this observation correlates with differences in the genesis of the respective cilia type and confirms that different molecular entities are recognized. A spatial segregation of immunoreactivity in the chemosensory epithelium was observed for one of the olfactory-specific monoclonal antibodies; negative zones were located in the dorsal recess of the nasal cavity and on the tips of the turbinates. Olfactory-specific antibodies reacted with distinct polypeptide bands on Western blots from olfactory ciliary preparations.

Animals↗