+----------------SUBJ:V-N----------------+                                    
      +-------COMP:N-N(of)-------+             +-------COMP:V-N(in)------+          
      |           +-MOD_ATT:N-ADJ+             |          +-MOD_ATT:N-ADJ+          
      |           |       +MOD_AT+        +-NEG+          |       +MOD_AT+          
      |           |       |      |        |    |          |       |      |          
 Expression of __SP__ __NODE__ mRNA does not occur in __NODE__ __SP__ thymus gland .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__SP__)
MOD_ATT:N-ADJ (mRNA,__NODE__)
SUBJ:V-N (occur,expression)
NEG (occur,not)
COMP:V-N(in) (occur,thymus)
MOD_ATT:N-ADJ (thymus,__NODE__)
MOD_ATT:N-ADJ (thymus,__SP__)