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At least 325 records · Page 18Linked to original sources
PubMed2003

Olfactive detection of fig wasps as prey by the ant Crematogaster scutellaris (Formicidae; Myrmicinae).

In the species-specific and obligate mutualism between the fig (Ficus carica) and its pollinator (the fig wasps Blastophaga psenes), a third participant, the ant Crematogaster scutellaris, is a predator of the wasps. Here, we ask how ant workers can rapidly localise such prey, whose availability is limited in time and space. Using a Y-tube olfactometer, we tested ant response to odours emitted by different types of figs (receptive female, ripe female or male figs) and by fig wasps (pollinators or non-pollinators). We demonstrate that ants were significantly attracted only to odours emitted by pollinators, either alone or associated with odours of male figs (releasing wasps). Detection of prey odour by ants is an important trait that can explain their observed high rate of predation on pollinators, and could have important implications on the stability of the fig/fig wasp mutualism.

Animals↗
PubMed2002

Intranasal chemosensory function of the trigeminal nerve and aspects of its relation to olfaction.

OBJECTIVES: The review outlines characteristics of the intranasal trigeminal chemosensory system. In addition, it provides selective comparisons of the trigeminal and olfactory systems, the two of which interact at multiple levels. RESULTS AND CONCLUSIONS: This interaction between the trigeminal and olfactory systems is an important determinant of sensations of odor. Further, it appears to change as a result of aging and disease. Thus, the interaction between the olfactory and trigeminal systems is not straightforward and may be difficult to predict, but it has a powerful influence on the perception of odors.

Aging↗
PubMed2000

Sustaining olfaction at low salinities: evidence for a paracellular route of ion movement from the hemolymph to the sensillar lymph in the olfactory sensilla of the blue crab Callinectes sapidus.

Evidence reported previously suggests that in low-salinity conditions the integrity of the olfactory dendrites of the blue crab is sustained by a diffusion-generated ionic microenvironment within the aesthetascs. Diffusion of ions from the hemolymph to the sensillar lymph is proposed to maintain this microenvironment. In this study, using lanthanum as an electron-dense marker of extracellular fluid space, we find morphological evidence for paracellular continuity between the hemolymph and the sensillar lymph. Lanthanum penetrates extracellular fluid spaces within the aesthetascs when antennules are either perfused or bathed externally with solutions containing lanthanum nitrate. This was found in both freshwater- and seawater-acclimated animals. Evidence for ion diffusion from the aesthetascs was obtained using self-referencing, ion-selective microelectrodes. Both Ca2+ and K+ exhibit outwardly directed flux gradients associated with the aesthetasc tuft in low-salinity conditions. These findings are consistent with the concept that ion diffusion from the hemolymph to the sensillar lymph generates an ionic/osmotic microenvironment within the aesthetascs at low salinities.

Adaptation, Physiological↗
PubMed1999

Assessing olfaction in the Italian population: methodology and clinical application.

Disorders of the sense of smell are receiving growing clinical as well as experimental attention. Indeed, several neurological conditions have been associated with peripheral or central deficits of the olfactory system. In recent years, particular emphasis has been attributed to the early and severe olfactory impairment in neurodegenerative diseases, such as Alzheimer's dementia and Parkinson's disease. Olfactory assessment has also been included in comprehensive pre- and post-surgical evaluations of temporal lobe epilepsy. Moreover, the request for standardized methods of olfactory evaluation by forensic and occupational medicine is greatly increasing. Despite this requirement, there is no agreement in the Italian neurological community on olfactory assessment. This lack prompted us to generate a battery of standardized tests capable of bypassing cross-cultural differences in olfactory assessment and to be potentially useful in the clinical as well as experimental settings. Procedures of assessment of olfactory acuity (detection threshold), identification (multiple choice odor naming), discrimination (differentiation between similar/dissimilar odorants) and memory (recognition of a substance previously smelled) are fully described. In order to control bias factors depending upon the nature of the investigated disorder and the applied olfactory tasks, a minimal complementary neuropsychological assessment is recommended.

Humans↗
PubMed1991

cDNA and derived amino acid sequence of rabbit nasal cytochrome P450NMb (P450IIG1), a unique isozyme possibly involved in olfaction.

Olfactory-specific cytochrome P450NMb was previously purified to electrophoretic homogeneity from microsomes of rabbit nasal mucosa in this laboratory. In the present study, a cDNA library made from poly(A)+ RNA from rabbit nasal mucosa was screened with antibodies to this P450, and eight immunopositive clones were isolated and characterized. The sequence determined from two overlapping clones contained an open reading frame of 1446 nucleotides, with the predicted first 39 amino acids corresponding to residues 12 to 50 of purified NMb, except for position 46, where Leu was encoded instead of the Glu residue that was found earlier by Edman degradation analysis. The complete polypeptide, including residues 1 to 11, contains 494 amino acid residues and has a molecular weight of 56,640. Sequence comparisons indicated that NMb is more than 50% identical to members of the rabbit P450 gene II family, including IIB4, IIC3, IIC5, IIE1, and IIE2, and 83% identical to rat P450olf1 (IIG1). Hybridization of NMb to electrophoretically fractionated rabbit nasal poly(A)+ RNA revealed 3.6- and 2.1-kb species, but with a probe derived from the 3'-nontranslated portion of the cDNA only the 3.6-kb band was observed, suggesting the use of alternate polyadenylation sites or splicing. In agreement with the known tissue-specific distribution of NMb protein, NMb transcripts were found in olfactory mucosa, but not in liver, lung, intestine, or kidney. Genomic hybridization analysis indicated that there may be only one copy of the NMb gene present in the rabbit genome.

Amino Acid Sequence↗
PubMed1992

Hippocampal activity, olfaction, and sniffing: an olfactory input to the dentate gyrus.

Experiments in freely moving rats showed that olfactory stimuli elicit a burst of rhythmical 15-30 Hz waves in or near the hilus of the dentate gyrus but not in adjacent regions of CA1. This fast wave burst is not elicited by visual, auditory, or somatosensory inputs and is not related to motor activity. Electrical stimulation of the olfactory bulb evokes a complex potential in the hilus of the dentate gyrus but not in adjacent regions of CA1. Experiments making use of wave-triggered averaging demonstrated that there is a degree of phase-locking between (a) hippocampal RSA and sniffing or other respiratory patterns, (b) hippocampal RSA and the initiation of jumping, and (c) respiration and the initiation of jumping. An early hypothesis that the hippocampus and dentate gyrus are part of an olfacto-motor mechanism may merit re-examination.

Animals↗
PubMed1992

Receptor cell regeneration and connectivity in olfaction and taste.

The capacity of adult mammalian gustatory and olfactory receptor cells to regenerate and make synaptic reconnections provides examples that may be useful in initiating replacement of other kinds of sensory receptor cells. The sensory code for taste quality may not be degraded by taste receptor cell turnover because axons probably recouple to the appropriate type of new receptor cell by axon-receptor cell affinity. Experiments on the development and regeneration of taste receptor cells suggest that they regenerate and turn over by recapitulating the late but not the early steps in taste bud development. To evaluate the replacement of vertebrate olfactory receptors, we began by characterizing the spatial pattern of primary olfactory projections in rainbow trout. Contiguous clusters of HRP-labeled olfactory receptor neurons (ORN) make highly divergent projections to the olfactory bulb. Retrograde transport of fluorescent latex beads revealed that a given restricted site in the glomerular layer received axons from ORNs widely scattered in the epithelium. Hence, ORN axons do not form point-to-point or regional topographic maps. Rather, the olfactory epithelial sheet makes a plane-to-point or holographic-like projection, since any given point in the glomerular layer receives information from the entire olfactory epithelial plane. Receptor cells that reacted with the lectin pokeweed agglutinin were highly dispersed in the olfactory epithelium with axons widely scattered in the olfactory nerve. Yet, as a consequence of the extensive reaggregation of axons at the nerve-bulb interface, the lectin-positive axons fasciculated and converged into a subregion of the glomerular layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

Ability of the pig to distinguish between conspecific urine samples using olfaction.

In two female pigs it has been shown using operant conditioning techniques in which the animals pushed panels with their snouts in order to obtain food, that they could distinguish between the oder from urine samples taken from other pigs. In the discrimination task, the pigs faced two panels and a tube adjacent to one of the panels emitted urine odor used as the positive discriminative stimulus while another tube adjacent to the other panel emitted the negative discriminative stimulus consisting of odor from another urine sample. Only presses on the panel associated with the positive stimulus were reinforced on a fixed ratio schedule of 6. Both positive and negative discrimination stimuli were presented simultaneously. After each reinforcement the position of the positive and negative odor stimuli was varied according to the Gellerman series. When fully trained, the pigs made very few responses on the incorrect panel.

Animals↗