Proteomic analysis of castor bean tick Ixodes ricinus: a focus on chemosensory organs.
In arthropods, the large majority of studies on olfaction have been focused on insects, where most of the proteins involved have been identified. In particular, chemosensing in insects relies on two families of membrane receptors, olfactory/gustatory receptors (ORs/GRs) and ionotropic receptors (IRs), and two classes of soluble proteins, odorant-binding proteins (OBPs) and chemosensory proteins (CSPs). In other arthropods, such as ticks and mites, only IRs have been identified, while genes encoding for OBPs and CSPs are absent. A third class of soluble proteins, called Niemann-Pick C2 (NPC2) has been suggested as potential carrier for semiochemicals both in insects and other arthropods. Here we report the results of a proteomic analysis on olfactory organs (Haller's organ and palps) and control tissues of the tick Ixodes ricinus, and of immunostaining experiments targeting NPC2s. Adopting different extraction and proteomic approaches, we identified a large number of proteins, and highlighted those differentially expressed. None of the 13 NPC2s known for this species was found. On the other hand, using immunocytochemistry, we detected reaction against one NPC2 in the Haller's organ and palp sensilla. We hypothesized that the low concentration of such proteins in the tick's tissues could possibly explain the discrepant results. In ligand-binding assays the corresponding recombinant NPC2 showed good affinity to the fluorescent probe N-phenylnaphthylamine and to few organic compounds, supporting a putative role of NPC2s as odorant carriers.
Biology Department, University of Firenze, via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
Immacolata
I
Iovinella
Department of Grassland Science, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
Liping
L
Ban
Department of Grassland Science, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
Limei
L
Song
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Paolo
P
Pelosi
Biology Department, University of Firenze, via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy; CISM, Mass Spectrometry Centre, University of Firenze, Via U. Schiff 6, 50019 Sesto Fiorentino, Italy. Electronic address: francescaromana.dani@unifi.it.
Francesca Romana
FR
Dani
D000818:Animals; D057506:Arthropod Antennae / Q000502:physiology*; D060829:Arthropod Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D018884:Ixodes / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D008297:Male; D009758:Nymph / Q000254:growth & development; D020543:Proteome; D040901:Proteomics; D018035:Receptors, Odorant / Q000235:genetics* / Q000378:metabolism
D060829:Arthropod Proteins; D020543:Proteome; D018035:Receptors, Odorant; C045648:odorant-binding protein
Haller’s organ; Olfaction; Proteomics; Soluble olfactory proteins; Ticks