Synapsin I expression in spinal cord neurons during chick embryo development.
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.
Plateroti
M
M
Dipartimento di Biologia Cellulare e dello Sviluppo, Università di Roma La Sapienza, Italy.
Vignoli
A L
AL
Biagioni
S
S
Di Stasi
A M
AM
Petrucci
T C
TC
Augusti-Tocco
G
G
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
D012333:RNA, Messenger; D016704:Synapsins