title: Synapsin I expression in spinal cord neurons during chick embryo development.
abstract: The cellular distribution of synapsin I in chick spinal cord has been examined during embryo development and in cultured neurons from different developmental stages. Using immunocytochemical methods we have observed that synapsin I appears lightly detectable in spinal cord of embryonic day (E)5-E8 embryos when the motor neurons have already established functional contacts with muscle fibers, and increases at E9. Until E8 synapsin I immunoreactivity appeared mainly localized in the gray matter of spinal cord; immunostaining of white matter becomes clearly evident only at E9. These observations indicate that synapsin I expression and possibly its transport to the nerve terminals may be stimulated by sequential signals. The cellular distribution of synapsin I observed in vivo is maintained in E8 and E9 spinal cord neuron cell cultures. In fact, in E8 cultured neurons, synapsin I immunostaining is observed only in the cell body, while in E9 cultured neurons both cell body and fibers are stained. The addition of muscle extracts to E8 cultures induces synapsin I decoration of fibers similar to that observed in E9 cultured neurons. Indeed Western and Northern blot analysis and in situ hybridization demonstrate an increase of synapsin I and its mRNA in spinal cord neurons kept in the presence of muscle extracts. These data suggest that synapsin I expression, as previously reported for other neuronal markers, can be modulated by soluble factors present in target cells.
authors.affiliation: Dipartimento di Biologia Cellulare e dello Sviluppo, Università di Roma La Sapienza, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Plateroti
authors.forename: A L
authors.initials: AL
authors.lastname: Vignoli
authors.forename: S
authors.initials: S
authors.lastname: Biagioni
authors.forename: A M
authors.initials: AM
authors.lastname: Di Stasi
authors.forename: T C
authors.initials: TC
authors.lastname: Petrucci
authors.forename: G
authors.initials: G
authors.lastname: Augusti-Tocco
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D002642:Chick Embryo; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D009474:Neurons / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D013116:Spinal Cord / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D016704:Synapsins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D016704:Synapsins