Continuous and overlapping expression domains of odorant receptor genes in the olfactory epithelium determine the dorsal/ventral positioning of glomeruli in the olfactory bulb.
In mammals, olfactory signals received by odorant receptors (ORs) in the olfactory epithelium (OE) are converted to a topographical map of activated glomeruli in the olfactory bulb (OB). It has been reported that the OE can be divided into four topographically distinct zones and that olfactory sensory neurons (OSNs) expressing a particular OR gene are randomly distributed within one zone. Here, we analyzed 80 different class II OR genes for their expression patterns in the OE by in situ hybridization. It was found that the expression area in the OE does not always fit into one of the four conventional zones. Expression areas are specific to each OR gene and are arranged in an overlapping and continuous manner in the OE. We also analyzed a spatial relationship between the OE and the OB for OSN projection. Our transgenic as well as DiI retrograde staining experiments demonstrated that the dorsal/ventral arrangement of glomeruli in the OB is correlated with the expression areas of corresponding ORs along the dorsomedial/ventrolateral axis in the OE. The present study indicates that the OR gene choice may be more restricted by the OSN location in the OE than what has been thought.
Miyamichi
Kazunari
K
Core Research for Evolutional Science and Technology, The University of Tokyo, Tokyo 113-0032, Japan.
Serizawa
Shou
S
Kimura
Hiroko M
HM
Sakano
Hitoshi
H
D000818:Animals; D001369:Axons / Q000378:metabolism; D002232:Carbocyanines / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D017403:In Situ Hybridization / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008967:Molecular Biology / Q000379:methods; D009414:Nerve Growth Factors / Q000235:genetics; D009830:Olfactory Bulb / Q000166:cytology* / Q000378:metabolism; D009831:Olfactory Mucosa / Q000166:cytology* / Q000378:metabolism*; D009833:Olfactory Pathways / Q000033:anatomy & histology / Q000378:metabolism; D018034:Olfactory Receptor Neurons / Q000378:metabolism*; D018035:Receptors, Odorant / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D014909:Wheat Germ Agglutinins / Q000096:biosynthesis / Q000235:genetics; D016875:tau Proteins / Q000096:biosynthesis / Q000235:genetics
C035005:3,3'-dihexadecylindocarbocyanine; D002232:Carbocyanines; D009414:Nerve Growth Factors; D018035:Receptors, Odorant; D014909:Wheat Germ Agglutinins; D016875:tau Proteins; D049452:Green Fluorescent Proteins