Ra. Steinbrecht et al., IMMUNOLOCALIZATION OF PHEROMONE-BINDING PROTEIN AND GENERAL ODORANT-BINDING PROTEIN IN OLFACTORY SENSILLA OF THE SILK MOTHS ANTHERAEA AND BOMBYX, Cell and tissue research, 282(2), 1995, pp. 203-217
The distribution of odorant-binding proteins among olfactory sensilla
of three moth species was studied by immune-electron microscopy. Two p
olyclonal antisera were used in a post-embedding labelling protocol on
sections of cryo-substituted antennae. The first was directed against
the pheromone-binding protein (PBP) of Antheraea polyphemus, the seco
nd against the general odorant-binding protein (GOBP) of the same spec
ies. Immunoblots showed that these antisera were highly specific; both
antisera did, however, cross-react with related proteins in the relat
ed species A. pernyi, and in the bombycid moth B. mori. PBP and GOBP w
ere localized only in olfactory sensilla trichodea and sensilla basico
nica, the principal site being the sensillum lymph surrounding the sen
sory dendrites. In the males of all three species, the pheromone-sensi
tive long sensilla trichodea exclusively contained PBP. The majority o
f the sensilla basiconica in both sexes in these species contained GOB
P; these sensilla are known to respond to plant and other 'general' od
ours. Some sensilla were not labelled by either antiserum; presumably,
these held an odorant-binding protein of a different subfamily. Never
were PBP and GOBP co-localized in the same sensillum. Two observation
s deserve special attention: (1) PBP was also found in a few sensilla
in females, and (2) in B. mori, where the long sensilla trichodea have
a different functional specificity in males (pheromone) and females (
plant odours), the expression of the odorant-binding protein (males: P
BP; females: GOBP) is similarly different. The distinct and complex di
stribution pattern of odorant-binding proteins supports the notion tha
t these proteins participate in stimulus recognition.