Biochemical Evidence for a Putative Inositol 1,3,4,5-Tetrakisphosphate Receptor in the Olfactory System of Atlantic Salmon (Salmo salar)

Olfactory receptor neurons in Atlantic salmon (Salmo salar) appear to use a phosphoinositide-directed phospholipase C (PLC) in odorant signal transduction. The consequences of odor-activated PLC depend on its product, inositol 1,4,5-trisphosphate (IP3). Therefore, a plasma membrane rich (PMR) fraction, previously characterized from salmon olfactory rosettes, was used to study binding sites for IP3 and its phosphorylation product, inositol 1,3,4,5-tetrakisphosphate (IP4). Binding sites for IP3 were present at the lower limit for detection in the PMR fraction but were abundant in a microsomal fraction. Binding sites for IP4 were abundant in the PMR fraction and thus colocalized in the same subcellular fraction with odorant receptors for amino acids and bile acids. Binding of IP4 was saturable and high affinity (Kd = 83 nM). The rank order for potency of inhibition of IP4 by other inositol polyphosphates (InsPx) followed the phosphorylation number with InsP6 > InsP5 > other InsP4 isomers > InsP3 isomers > InsP2 isomers, with the latter showing no activity. The consequences of PLC activity in this system may be dictated in part by a putative receptor for IP4.

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Localization of 2-[125l]lodomelatonin Binding Sites in the Brain of the Atlantic Salmon, Salmo salar L

Neuroendocrinology ◽

10.1159/000126166 ◽

1992 ◽

Vol 55 (5) ◽

pp. 529-537 ◽

Cited By ~ 77

Author(s):

Peter Ekström ◽

Jirˇí Vaněček

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Binding Sites ◽

Atlantic Salmon Salmo Salar ◽

The Brain

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An update on anatomy and function of the teleost olfactory system

PeerJ ◽

10.7717/peerj.7808 ◽

2019 ◽

Vol 7 ◽

pp. e7808 ◽

Cited By ~ 5

Author(s):

Jesús Olivares ◽

Oliver Schmachtenberg

Keyword(s):

Olfactory System ◽

Olfactory Receptor Neurons ◽

Odorant Receptors ◽

Odor Coding ◽

Animal Group ◽

Different Types ◽

Olfactory Systems ◽

Receptor Neurons ◽

Olfactory Organs ◽

And Function

About half of all extant vertebrates are teleost fishes. Although our knowledge about anatomy and function of their olfactory systems still lags behind that of mammals, recent advances in cellular and molecular biology have provided us with a wealth of novel information about the sense of smell in this important animal group. Its paired olfactory organs contain up to five types of olfactory receptor neurons expressing OR, TAAR, VR1- and VR2-class odorant receptors associated with individual transduction machineries. The different types of receptor neurons are preferentially tuned towards particular classes of odorants, that are associated with specific behaviors, such as feeding, mating or migration. We discuss the connections of the receptor neurons in the olfactory bulb, the differences in bulbar circuitry compared to mammals, and the characteristics of second order projections to telencephalic olfactory areas, considering the everted ontogeny of the teleost telencephalon. The review concludes with a brief overview of current theories about odor coding and the prominent neural oscillations observed in the teleost olfactory system.

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In vivo uptake of radiothyroxine by the tissues of Atlantic salmon (Salmo salar L.) parr, presmolt, and smolt

Canadian Journal of Zoology ◽

10.1139/z69-003 ◽

1969 ◽

Vol 47 (1) ◽

pp. 9-16 ◽

Cited By ~ 5

Author(s):

J. G. Eales

Keyword(s):

Atlantic Salmon ◽

Gall Bladder ◽

Salmo Salar ◽

Binding Sites ◽

Intraperitoneal Injection ◽

Tissue Uptake ◽

Serum Free ◽

In Vivo Uptake ◽

Atlantic Salmon Parr

Tissue uptake of radiothyroxine in Atlantic salmon parr, presmolts, and smolts held at 10.5 to 13.5 °C was assessed by measuring T/S ratios (tissue radioactivity/serum radioactivity) from 1 hour to 10 days after intraperitoneal injection of L-thyroxine–125I.T/S ratios were highest for gall bladder, liver, and gut, indicating a biliary thyroxine excretion route. Somewhat less uptake occurred in spleen, kidney, and gill. T/S ratios were lower still for skin and muscle but the pattern of T/S change with time suggested some radiothyroxine uptake by these tissues. Little uptake occurred in brain where low T/S ratios were consistently found.For most tissues there was no difference in thyroxine uptake between parr, smolts, and presmolts. However, for presmolts the means of gill T/S ratios were much higher than those for parr or smolts while the biliary thyroxine excretion route was most prominent in parr.The biological half-life of serum radioactivity after intraperitoneal injection of L-thyroxine–125I was similar for parr, presmolt, and smolt. Most of the serum radioactivity was not protein-bound and was probably free radiothyroxine. The injected radiothyroxine may have so increased the serum free thyroxine pool that serum protein thyroxine-binding sites were saturated.

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Origin of basal activity in mammalian olfactory receptor neurons

The Journal of General Physiology ◽

10.1085/jgp.201010528 ◽

2010 ◽

Vol 136 (5) ◽

pp. 529-540 ◽

Cited By ~ 44

Author(s):

Johannes Reisert

Keyword(s):

Olfactory Receptor ◽

Information Transfer ◽

Odorant Receptor ◽

Olfactory Receptor Neurons ◽

Odorant Receptors ◽

Action Potential Firing ◽

Response Characteristics ◽

Basal Activity ◽

Receptor Neurons ◽

Different Response

Mammalian odorant receptors form a large, diverse group of G protein–coupled receptors that determine the sensitivity and response profile of olfactory receptor neurons. But little is known if odorant receptors control basal and also stimulus-induced cellular properties of olfactory receptor neurons other than ligand specificity. This study demonstrates that different odorant receptors have varying degrees of basal activity, which drives concomitant receptor current fluctuations and basal action potential firing. This basal activity can be suppressed by odorants functioning as inverse agonists. Furthermore, odorant-stimulated olfactory receptor neurons expressing different odorant receptors can have strikingly different response patterns in the later phases of prolonged stimulation. Thus, the influence of odorant receptor choice on response characteristics is much more complex than previously thought, which has important consequences on odor coding and odor information transfer to the brain.

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Ir76b is a Co-receptor for Amine Responses in Drosophila Olfactory Neurons

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.759238 ◽

2021 ◽

Vol 15 ◽

Author(s):

Alina Vulpe ◽

Karen Menuz

Keyword(s):

Olfactory Receptor ◽

Olfactory Receptors ◽

Olfactory Receptor Neurons ◽

Odorant Receptors ◽

Olfactory Neurons ◽

Bona Fide ◽

Receptor Neurons ◽

Large Families ◽

Odorant Binding

Two large families of olfactory receptors, the Odorant Receptors (ORs) and Ionotropic Receptors (IRs), mediate responses to most odors in the insect olfactory system. Individual odorant binding “tuning” OrX receptors are expressed by olfactory neurons in basiconic and trichoid sensilla and require the co-receptor Orco. The situation for IRs is more complex. Different tuning IrX receptors are expressed by olfactory neurons in coeloconic sensilla and rely on either the Ir25a or Ir8a co-receptors; some evidence suggests that Ir76b may also act as a co-receptor, but its function has not been systematically examined. Surprisingly, recent data indicate that nearly all coeloconic olfactory neurons co-express Ir25a, Ir8a, and Ir76b. Here, we demonstrate that Ir76b and Ir25a function together in all amine-sensing olfactory receptor neurons. In most neurons, loss of either co-receptor abolishes amine responses. In contrast, amine responses persist in the absence of Ir76b or Ir25a in ac1 sensilla but are lost in a double mutant. We show that responses mediated by acid-sensing neurons do not require Ir76b, despite their expression of this co-receptor. Our study also demonstrates that one population of coeloconic olfactory neurons exhibits Ir76b/Ir25a-dependent and Orco-dependent responses to distinct odorants. Together, our data establish the role of Ir76b as a bona fide co-receptor, which acts in partnership with Ir25a. Given that these co-receptors are among the most highly conserved olfactory receptors and are often co-expressed in chemosensory neurons, our data suggest Ir76b and Ir25a also work in tandem in other insects.

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