Functional Asymmetry in the Olfactory System of a Flatfish, the Senegalese Sole (Solea senegalensis) Zélia Velez 1,2,3 , Peter C. Hubbard 1 , Kevin J. Weham 3 , Eduardo N. Barata 1,2 , Jörg D. Hardege 3 and Adelino V.M. Canário 1 1. Centro de Ciências do Mar, Faro, Portugal; 2. Departamento de Biologia, Universidade de Évora, Portugal; 3. University of Hull, UK
21
Embed
Functional Asymmetry in the Olfactory System of a Flatfish, the Senegalese Sole (Solea senegalensis) Zélia Velez 1,2,3, Peter C. Hubbard 1, Kevin J. Weham.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Functional Asymmetry in the Olfactory System of a Flatfish, the
Senegalese Sole (Solea senegalensis)
Zélia Velez1,2,3, Peter C. Hubbard1, Kevin J. Weham3, Eduardo N. Barata1,2, Jörg D. Hardege3
and Adelino V.M. Canário1
1. Centro de Ciências do Mar, Faro, Portugal; 2. Departamento de Biologia,
Universidade de Évora, Portugal; 3. University of Hull, UK
High commercial value – increased aquaculture effort.Flatfish; left (lower) nostril does not migrate.
Functional asymmetry in the olfactory system?Lower epithelium – prey location/identificationUpper epithelium – chemical communication
The Selenagese Sole (Solea senegalensis):
Methods:
Electro-olfactogram (EOG) recorded from the olfactory epithelium:
Solid-phase extraction – crude separation of odorantsHPLC – fine separation and purification of odorantsLC-MS – identification of odorants
Methods:
The ragworm Hediste diversicolor is one of the sole’s main prey.They live buried in the sand or mud (of estuaries).Bile acids are potent odorants in fish.
Food- and conspecific-related odorants
Bile and intestinal fluidRagworm-conditioned water
C-18 Sep-Pak
Total; EOG
Filtrate HPLCand EOG
EluateEOG
Methods:
EOG is a spacio-temporal summation of generator potentials of olfactory receptor neurones. L-cysteine is detected with equal sensitivity by the two olfactory epithelia; responses are normalised to that of 10-3 M L-cysteine.
The electro-olfactogram (EOG)
Velez et al. (2005) Physiol. Biochem. Zool. 78: 756-765
Results I:
Fractions 1 and 2 contain the odorants of interest; active odorant identified using LC-MS
Upper epithelium has greater specificity for taurocholic acid.
Adapting solution
L-cysteine 1-M-L-T Cholic acid
% c
ontr
ol r
espo
nse
0
20
40
60
80
100 UpperLower
*** ***
***
taurocholic acid
Results II: Transduction
L-cysteine is detected equally by the two epitheliaThe effects of the two drugs are the same in the two epithliaThe transduction pathway for L-cysteine is mainly via PLC
U73122 – PLC inhibitorSQ-22536 – AC inhibitor
U73122 SQ-22536 Both
% c
ontr
ol r
espo
nse
0
20
40
60
80
100 Upper
Lower
a x
b y
c x
log[U73122] (M)
-9 -8 -7 -6
Nor
ma
lise
d E
OG
Am
plitu
de
0.0
0.2
0.4
0.6
0.8
1.0
L-cysteine L-cysteine
Results II: Transduction
The transduction pathway for 1-methyl-L-tryptophan is mainly PLC mediated
There are differences between the two epithelia
U73122 SQ-22536 Both
% c
ontr
ol r
espo
nse
0
20
40
60
80
100
120 UpperLower
**
**
a
b
cx
y
x
1-methyl-L-tryptophan
U73122 – PLCSQ-22536 – AC
Results II: Transduction
Both phospholipase C and adenylate cyclase are involved in transduction of taurocholic acid
There are differences in the two epithelia
U73122 SQ-22536 Both
% c
ontr
ol r
espo
nse
0
20
40
60
80
100 UpperLower
***
**
*
a
abb
x
y
x
taurocholic acid
U73122 – PLCSQ-22536 – AC
Conclusions II:
There are specific receptors for 1-methyl-L-tryptophan in the lower epithelium.
There are specific receptors for taurocholic acid in the upper epithelium.
The transduction pathway for 1-methyl-L-tryptophan is mainly phospholipase C mediated.
The transduction pathway(s) for taurocholic acid is/are mediated by both phospholipase C and adenylate cyclase.
Summary:
Specific receptors in the lower olfacotry epithelium for prey-related odorants (1-methyl-L-tryptophan)
Specific receptors in the upper olfactory epithelium for conspecific-related odorants (taurocholic acid)
This suggests specialisation of the two epithelia – functional asymmetry
Does the processing of the olfactory information in the olfactory bulb (and beyond) also show asymmetry?
The End:
Thank you for your attention
Funded by FCT grants SFRH/BD/16242/2004 and POCI/BIA-BMC/55467/2004