title: Mutations affecting the formation of posterior lateral line system in Medaka, Oryzias latipes.
abstract: We performed a systematic screen for mutations affecting the trajectory of axons visualized by immunohistochemical staining of Medaka embryos with anti-acetylated tubulin antibody. Among the mutations identified, yanagi (yan) and kazura (kaz) mutations caused specific defects in projection of the posterior lateral line (PLL) nerve. In yan and kaz mutant embryos, the PLL nerve main bundle was misrouted ventrally and dorsally or anteriorly. Medaka semaphorin3A, sdf1, and cxcr4 cDNA fragments were cloned to allow analysis of these mutants. There were no changes in semaphorin3A or sdf1 expression in mutant embryos, suggesting that the tissues expressing semaphorin3A or sdf1 that are involved in PLL nerve guidance are present in these mutant embryos. Double staining revealed that the mislocated PLL primordium and growth cone of the ectopically projected PLL nerve were always colocalized in both yan and kaz mutant embryos, suggesting that migration of PLL primordia and PLL nerve growth cones are not uncoupled in these mutants. Although homozygous yan larvae showed incomplete migration of the PLL primordium along the anteroposterior axis, ventral proneuromast migration was complete, suggesting that ventral migration of the proneuromast does not require the signaling affected in yan mutants. In addition to the PLL system, the distribution of primordial germ cells (PGCs) was also affected in both yan and kaz mutant embryos, indicating that yan and kaz genes are required for the migration of both PLL primordia and PGCs. Genetic linkage analysis indicated that kaz is linked to cxcr4, but yan is not linked to sdf1 or cxcr4. These mutations will provide genetic clues to investigate the molecular mechanism underlying formation of the PLL system.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Yasuoka
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Hirose
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yoda
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Aihara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suwa
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Niwa
authors.forename: Takao
authors.initials: T
authors.lastname: Sasado
authors.forename: Chikako
authors.initials: C
authors.lastname: Morinaga
authors.forename: Tomonori
authors.initials: T
authors.lastname: Deguchi
authors.forename: Thorsten
authors.initials: T
authors.lastname: Henrich
authors.forename: Norimasa
authors.initials: N
authors.lastname: Iwanami
authors.forename: Sanae
authors.initials: S
authors.lastname: Kunimatsu
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
authors.forename: Hisato
authors.initials: H
authors.lastname: Kondoh
authors.forename: Makoto
authors.initials: M
authors.lastname: Furutani-Seiki
mesh_terms: D000818:Animals; D009154:Mutation; D009990:Oryzias / Q000196:embryology* / Q000235:genetics*; D010525:Peripheral Nerves / Q000196:embryology; D011984:Sensory Receptor Cells / Q000196:embryology*