(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Opisthokonta: NE > Metazoa: NE > Eumetazoa: NE > Bilateria: NE > Protostomia: NE > Ecdysozoa: NE > Panarthropoda: NE > Arthropoda: NE > Mandibulata: NE > Pancrustacea: NE > Crustacea: NE > Maxillopoda: NE > Copepoda: NE > Neocopepoda: NE > Podoplea: NE > Siphonostomatoida: NE > Caligidae: NE > Lepeophtheirus: NE > Lepeophtheirus salmonis: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MWIQVRKHNLGLSFERILVYLLTLSWSLGSIVQEDLVITTRKGKIRGVTL KSATNKEVDAWYGIPYAQPPVGNLRFRHPKDINAWDGMKETTKHPNSCIQ VVDTFFPGFEGSEMWNTNTEQSEDCLYLSVHAPKPRPTKSAVLVWIYGGG FYSGTSTLELYDPRVLVSEENIIFVGIQYRVASLGFLFFDTEDVPGNAGL YDQMMALQWVKNNIEAFGGDPDKITIFGESAGGCSVALHLLSPLSRNLFS QAIMQSSSALVPWGVISKKESIRRGRRLAEEMRCPYGENNTNAMIECLLQ KDATELVNQEWSGTVFGISEFPFVPIVDGKFMDKTPEKSLKEKDYKKTNI LMGVNKDEGNFFIMYYLPELFKKNENVYINRTDFIRSVSDLNIYVNNAGR EAITFEYTDWLNPNDPIKNREAIDRMVGDYQFICPTADFARIYASTGNNI YMYYFTERSSTSPWPTWSGVLHGDEIAFVFGEPLNTSKNYDDSEIALSKR IMSYWANFAKTGNPNVLANGNYSNKIWPLHTPIKQEVLELNANYSRVFEG LRVRKCAFWKTYLPKLLSLTSNNTKSEVVTNPS
References
Title: Mechanism behind Resistance against the Organophosphate Azamethiphos in Salmon Lice (Lepeophtheirus salmonis) Kaur K, Helgesen KO, Bakke MJ, Horsberg TE Ref: PLoS ONE, 10:e0124220, 2015 : PubMed
Acetylcholinesterase (AChE) is the primary target for organophosphates (OP). Several mutations have been reported in AChE to be associated with the reduced sensitivity against OP in various arthropods. However, to the best of our knowledge, no such reports are available for Lepeophtheirus salmonis. Hence, in the present study, we aimed to determine the association of AChE(s) gene(s) with resistance against OP. We screened the AChE genes (L. salmonis ace1a and ace1b) in two salmon lice populations: one sensitive (n=5) and the other resistant (n=5) for azamethiphos, a commonly used OP in salmon farming. The screening led to the identification of a missense mutation Phe362Tyr in L. salmonis ace1a, (corresponding to Phe331 in Torpedo californica AChE) in all the samples of the resistant population. We confirmed the potential role of the mutation, with reduced sensitivity against azamethiphos in L. salmonis, by screening for Phe362Tyr in 2 sensitive and 5 resistant strains. The significantly higher frequency of the mutant allele (362Tyr) in the resistant strains clearly indicated the possible association of Phe362Tyr mutation in L. salmonis ace1a with resistance towards azamethiphos. The 3D modelling, short term survival experiments and enzymatic assays further supported the imperative role of Phe362Tyr in reduced sensitivity of L. salmonis for azamethiphos. Based on all these observations, the present study, for the first time, presents the mechanism of resistance in L. salmonis against azamethiphos. In addition, we developed a rapid diagnostic tool for the high throughput screening of Phe362Tyr mutation using High Resolution Melt analysis.
Title: Identification and Molecular Characterization of Two Acetylcholinesterases from the Salmon Louse, Lepeophtheirus salmonis Kaur K, Bakke MJ, Nilsen F, Horsberg TE Ref: PLoS ONE, 10:e0125362, 2015 : PubMed
Acetylcholinesterase (AChE) is an important enzyme in cholinergic synapses. Most arthropods have two genes (ace1 and ace2), but only one encodes the predominant synaptic AChE, the main target for organophosphates. Resistance towards organophosphates is widespread in the marine arthropod Lepeophtheirus salmonis. To understand this trait, it is essential to characterize the gene(s) coding for AChE(s). The full length cDNA sequences encoding two AChEs in L. salmonis were molecularly characterized in this study. The two ace genes were highly similar (83.5% similarity at protein level). Alignment to the L. salmonis genome revealed that both genes were located close to each other (separated by just 26.4 kbp on the L. salmonis genome), resulting from a recent gene duplication. Both proteins had all the typical features of functional AChE and clustered together with AChE-type 1 proteins in other species, an observation that has not been described in other arthropods. We therefore concluded the presence of two versions of ace1 gene in L. salmonis, named ace1a and ace1b. Ace1a was predominantly expressed in different developmental stages compared to ace1b and was possibly active in the cephalothorax, indicating that ace1a is more likely to play the major role in cholinergic synaptic transmission. The study is essential to understand the role of AChEs in resistance against organophosphates in L. salmonis.
