Morpholine, Bile Acids and Skin Mucus as Possible Chemical Cues in Salmonid Homing: Electrophysiological Re-Evaluation

  title={Morpholine, Bile Acids and Skin Mucus as Possible Chemical Cues in Salmonid Homing: Electrophysiological Re-Evaluation},
  author={Toshiaki J. Hara and S. Macdonald and Robert E. Evans and Takayuki Marui and Shigeru Arai},
The olfactory-imprinting and pheromone hypotheses of salmon homing recognize the involvement of olfaction in the recognition of the homestream. However, physiological basis for olfactory recognition and the nature of homestream odors have not yet been established. In this paper the state of knowledge and advances in the study of chemical cues relevant to salmonid homing are reviewed, with special emphasis on 1) imprinting to morpholine, 2) skin mucus as a chemical signal, and 3) chemoreceptor… 

Highly independent olfactory receptor sites for naturally occurring bile acids in the sea lamprey, Petromyzon marinus

Electro-olfactogram recording data demonstrate that conspecific bile acids are discriminated by the olfactory epithelium of the sea lamprey, supporting the possibility that these compounds may function as migratory pheromones.

Olfaction and gustation in fish: an overview.

  • T. Hara
  • Biology
    Acta physiologica Scandinavica
  • 1994
Putative receptors, molecular mechanisms of transduction and the role played by olfaction and gustation in feeding, reproduction, migration and other fish behaviours are discussed.

Sublethal effects of copper on coho salmon: Impacts on nonoverlapping receptor pathways in the peripheral olfactory nervous system

Examination of data indicates that copper is broadly toxic to the salmon olfactory nervous system, and short‐term influxes of copper to surface waters may interfere with Olfactory‐mediated behaviors that are critical for the survival and migratory success of wild salmonids.

High correlation between microvillous olfactory receptor cell abundance and sensitivity to pheromones in olfactory nerve-sectioned goldfish

Recovery of electro-olfactogram sensitivity to all odorants was slow and erratic over the next 6 months, particularly to the pheromones, and data suggest that microvillous receptor cells mediate responsiveness to phersomones in this species.

Olfactory sensitivity to amino acids in the juvenile stages of the European eel Anguilla anguilla (L.)

Recording of underwater electro-olfactograms (EOGs) showed that various amino acids (glycine, L-alanine,L-valine), L-leucine and L-asparagine are effective stimulants for the olfactory mucosa; leucine was more stimulatory at the GE than at the EL stage.

Lake char (Salvelinus namaycush) olfactory neurons are highly sensitive and specific to bile acids

It is concluded that lake char possess multiple olfactory receptors capable of discriminating bile acids produced and released by conspecifics.

Hormones, pheromones and chemoreception

This chapter reviews these advances from an historical perspective, paying particular attention to the endocrinological and neural basis of pheromone function in teleost fish, with emphasis on the goldfish, Carassius auratus, because it represents the best-understood model of sex pherOMone function.

A new model for olfactory imprinting in salmon

Results suggest that populations of olfactory receptor neurons may be selectively tuned to respond to odor molecules present during a hormonally linked sensitive period of development.



Olfactory sensitivity to bile acids in salmonid fishes.

The results suggest that olfactory receptors are of two types, one responding to bile acids, the other to amino acids, and that 3 -alpha-hydroxysteroids are released from the fish into the water in quantities that suffice for detection by their o aroma system.

Olfactory Imprinting and Homing in Salmon

Exposure of farmed coho salmon, rainbow trout and fario trout, aged 18 months, to a chemical introduced in the natural production environment (mixed with the scents of the native river), to determine if they will be responsive to this product to locate their initial production environment during upstream migration.

Olfactory Bulbar Electrical Responses of Rainbow Trout (Salmo gairdneri) Exposed to Morpholine During Smoltification

It was confirmed that the morpholine-effect is caused by a mechanism not directly associated with the normal olfactory function, and N-ethylmaleimide, a sulfhydryl reagent, was used as a reagent to study the mechanism behind this effect.

Discrimination of Stream Odors by Fishes and Its Relation to Parent Stream Behavior

Preliminary tests with salmon proved that they can detect the stream odors, and that they were able to discriminate between them; it is postulated that the nature of the guiding odor must be such that it have meaning only for those salmon conditioned to it during their freshwater sojourn.

Evidence for Pheromone-influenced Homing by Migrating Atlantic Salmon, Salmo salar (L.)

  • D. Solomon
  • Biology, Environmental Science
  • 1973
Evidence is presented here which indicates that the homing of adult Atlantic salmon may be largely dependent on the presence of other individuals in the river, and that olfaction played an important part in home-stream recognition.

Chemical methods for fractionation of odorants produced by char smolts and tentative suggestions for pheromone origins.

  • F. Selset
  • Biology
    Acta physiologica Scandinavica
  • 1980
Fractionation of fish material containing odorants was used to fractionate the intestinal contents of 1 1/2 year old smolts of a population of anadromous char and the nature and origin of the attractive substances are discussed.

Electrophysiological Studies of Morpholine-Imprinted Coho Salmon (Oncorhynchus kisutch) and Rainbow Trout (Salmo gairdneri)

Responses to morpholine were specific in that another chemical similar to it did not elicit responses, which support the olfactory hypothesis that sal...

Olfactory responses to skin mucous substances in rainbow trout Salmo gairdneri.

  • T. HaraS. Macdonald
  • Environmental Science
    Comparative biochemistry and physiology. A, Comparative physiology
  • 1976

electrophysiological studies on the olfactory sense in char (Salmo alpinus L.).