$52

IPSILATERAL INTERPOSITORUBRAL PROJECTION AND ITS RELATION TO PLASTICITY. ~Nm~!g ~QN~ hN~ E~!Q M~A~AMi~ D~m@[!m~n! ~! DiRRhX~i~gi SUgiu~[iug~ ~U!![ Qf ~ngia~[ing ~i~n~ Q~hg ~niY~[~i!M~ !Rx~ngh~ ~fiQ~ Qaghg~ ~ngn

Partial denervation in the central nervous system of neonatal animals induces r e m o d e l i n g o f n e u r o n a l c i r c u i t s w h i c h c a n n o t be i n d u c e d i n a d u l t s . An e x p l a n a t i o n f o r t h i s d i f f e r e n c e i s t h e c o n t r i b u t i o n o f a c i r c u i t i n n e o n a t a l a n i m a l s t h a t d i s a p p e a r s a s d e v e l o p m e n t p r o c e e d s . When t h e i n t e r p o s i t u s n u c l e u s i n t h e k i t t e n i s d e s t r o y e d u n i l a t e r a l l y w i t h i n s e v e r a l w e e k s a f t e r b i r t h , b i l a t e r a l p r o j e c t i o n to t h e r e d n u c l e u s (RN) o c c u r s f r o m t h e r e m a i n i n g s i d e , a c c o r d i n g to T s u k a h a r a e t a l . T h e y a l s o r e p o r t e d t h a t i n t e r p o s i t o r u b r a l ( I P - R N ) p r o j e c t i o n i n t h e k i t t e n i s c o m p l e t e l y c o n t r a l a t e r a l , a s i n a d u l t s . I n t h e p r e s e n t s t u d y , we s h o w e d , u s i n g PHA-L , t h e p r e s e n c e o f i p s i l a t e r a l IP-RN p r o j e c t i o n i n t h e k i t t e n . F rom t h e f o l l o w i n g o b s e r v a t i o n s , we c o n c l u d e t h a t t h e i p s i l a t e r a l p r o j e c t i o n i n n o r m a l k i t t e n m i g h t c o n t r i b u t e t o t h e e s t a b l i s h m e n t o f i p s i l a t e r a l IP -RN p r o j e c t i o n a f t e r l e s i o n : I ) t h e p e r i o d o f p r e s e n c e o f i p s i l a t e r a l IP -RN p r o j e c t i o n i n n o r m a l k i t t e n c o i n c i d e s w i t h t h a t d u r i n g w h i c h h e m i c e r e b e l l e c t o m y i n d u c e s i p s i l a t e r a l IP -RN p r o j e c t i o n ; 2> i p s i l a t e r a l IP-RN f i b e r s i n b o t h n o r m a l a nd l e s i o n e d k i t t e n s e n t e r t h e RN v i a t h e s a m e p a t h w a y r e c r o s s i n g t h e m i d l i n e b e t w e e n t h e two n u c l e i .

PURIFICATION OF SC1 AND M7412 ANTIGENS. HIDEAKI TANAKA, AKEMI AGATA, AND KUNIHIKO OBATA, Department of Pharmacology, Gunma University School of Medicine, Maebashi 371, Japan.

Monoclonal antibody (MAb) SCI transiently and uniquely binds to the cell surface of motoneurons among various spinal cord neurons in chick embryos at early developmental stages. MAb M7412 transiently binds to the cell surfaces along the entire motoneuron axonal pathways, such as the anterior half of sclerotome, limb mesenchymal cells along the presumptive nerve trunks, and structures surrounding myotube clusters. Because of spacial and time correlation of these immunostainings with motoneuron axonal growth, the antigenic molecules are candidate molecules responsible for motoneuron axonal growth. To examine whether SCI and M7412 antigens participate in regulation of motoneuron axonal growth, both antigens were purified with immunoaffinity from NP-40 extract of I0-12E whole chick embryo membrane fraction. A single band was detected at an apparent molecular weight of approximately 100,000 for SCI and 70,000 for M7412 after SDA-PAGE and silver staining. RCA, LCA, PHA, and WGA lectins were found to bind to both purified antigens. Since rabbit polyclonal antibodies against the two purified antigens also showed the transient immunostaining patterns, we concluded that not only the epitopes but also the antigenic molecules are expressed transiently. (Supported by the Muscular Dystrophy Association to H.T.)

MONOCLONAL ANTIBODIES STAINING NERVE FIBERS OF DEVELOPING RAT BRAIN. TATSUNORI SEKI, YASUMASA ARAI, Department o_~f Anatomy, Juntendo University School of Medicine, 2-I-I, Hondo, Bunk[o-ku, Tokyo 113, Japan. ~ a l antibodies (MAbs) agains~ b~o~n-c-6"~ suspension of 6-day-old rat hypothalami were produced and screened by immunohistochemically staining 4% paraformaldehyde-fixed frozen sections of adult and 6-day-old rat hypothalamus. From a total of about 700 hybridoma lines, 16 reacted with glial elements and 12 with cell bodies of neurons or nerve fibers. Four reacted with cell nucleus of neurons, glia and ependymal cells, and one of these four MAbs, MAb-5F7 strongly stained the nerve fibers of embryonic rat brain, whereas adult brains were only weakly stained. Another MAb, MAb-7C3, stained the nerve fibers of both adult and embryonic brain. Immunoblot analysis revealed that both MAbs reacted with about an 30OKd protein of embryonic brain. In adult tissue, MAb-5F7 and MAb-TC3 did not react with the 300Kd protein, but with a less than iOKd protein (probably nuclear protein) and a 200Kd (probably neurofilament), respectively. These results suggest the existence of a protein which appears in nerve fibers during embryonic stages and probably shares antigenic determinants with neurofilament and nuclear protein. The similarity of antigenic determinants between neurofilament and nuclear proteins has already been reported (J Neurochem. 44, 149, 1985).