| Brachymystax lenok is a rare land-locked cold-water rare fish in China.At present,the distribution area of Brachymystax lenok is gradually reduced and the biomass has dropped sharply due to various human factors in China.In order to protect and recover the resources,the conservation of natural resources and artificial breeding was carried out.On the one hand,in the conservation of natural resources,migration spawning rate is crucial,and amino acids may be the smell of the migratory olfactory imprint of the salmon.On the other hand,palatability is an important prerequisite for fast intake and absorption of compound feed by fish.Therefore,it is necessary to add attractant to promote feeding and improve feeding efficiency.Amino acids can induce the olfactory behavior associated with feed and are considered one of the most effective attractant compounds.Behavioral and electrophysiological?EOG?methods were used in this study,the olfactory response of several water-soluble amino acids to Brachymystax lenok was in studied.Firstly,the olfactional behavior of eight water-soluble mono-amino acids?glutamic acid?Glu?aspartic acid?Asp?glycine?Gly?alanine?Ala?serine?Ser?proline?Pro?tyrosine?Tyr?cysteine?Cys??with high content in the habitat of Brachymystax lenok was studied,the sensitive amino acids were screened out.Finally,the EOG reaction was performed to identify the most sensitive amino acids in electrophysiology and behavior and the optimal concentration for the potential amino acid attractants of Brachymystax lenok.The experimental contents and results are as follows:?1?Olfactory responses to 8 different amino acids in Pink salmon Brachymystax lenok were determined by a modified Y maze experiment.The results showed that there was an obvious tendency of olfactory responses stimulated by the amino acid at concentration to 4.5×10-6M.It reveals that the Brachymystax lenok has the highest sensitivity to glutamic acid among 8 amino acids,the second is proline.And there is no significant difference of responses stimulated by the other 6 amino acids,proline,alanine,aspartic,glycine,aspartic,serine and tyrosine.According to the relative preference degree,the olfactory preference in the response of amino acids is in order as glutamic acid>proline>aspartic acid>cysteine>alanine>serine>tyrosine>glycine.The preference of olfactory behavior suggests that the olfactory epithelium sensitivity might be consistent with the components of dissolved amino acids in habitat of Brachymystax lenok.?2?The Y maze experiments were conducted to test the behavioral responses of Brachymystax lenok to the glutamic acid stimulus with a concentration of 1×10-5to1×10-9mol·L-1.According to the results of behavioral response scores and preference analysis,the relative preference of fish to 1×10-5,1×10-6,1×10-7,1×10-8,1×10-9mol·L-1 was 0.396,0.436,0.381,3.081,1.142,respectively.It was indicated that the fish had a negative tendency to 1×10-5,1×10-6,1×10-7mol·L-1 glutamic acid,but had a positive trend toward 1×10-8,1×10-9mol·L-1 glutamic acid,and there was a significant difference in 1×10-8mol·L-1 test group?P<0.05?.The response threshold of behavioral response was 4.5×10-8mol·L-1.The results indicate that glutamic acid can be used as a potential amino acid attractant for young Brachymystax lenok.?3?The olfactory trend of 10-8M glutamate in Brachymystax lenok was studied by electrophysiology?EOG?.The difference amplification method was used to record the signal,and the sensitivity of amino acids of different concentrations was determined by comparing the response amplitudes.According to the electrophysiological olfactory response,Glutamate at a concentration of c 10-8Man cause an amplitude response in the olfactory bulb. |
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