; R o o t E n t r y F M 8I C o m p O b j b W o r d D o c u m e n t * O b j e c t P o o l M 8I M 8I ' ( ) * + , - . / 0 1 F Microsoft Word 6.0 Document MSWordDoc Word.Document.6 ; , 9 w 9 y w , ! Abstract Marchalonis 9406280 Sharks belong to one of the most primitive vertebrate classes. This investigator has been studying the immune system of sharks for a number of years. The blood of these animals contains high levels of immunoglobulins, but this is IgM, a type of immunoglobulin which appears first in mammals in response to an antigen. Like human antibodies, these shark immunoglobulins show a large diversity in sequence. With the recombinant DNA technologies this laboratory was able to determine the sequence of the genes and their corresponding proteins, and found that the mechanisms for generating diversity in these immunoglobulins differs from that of mammals. In sharks the V (variable), J (joining) and C (constant) regions are not separate as in mammals, with their products coming together and combining to form different immunglobulin molecules, but exist in V,J,C clusters. Nevertheless the proteins of the shark show great diversity and a lot of similarity to the mammalian chains. More recent studies from this laboratory show that the RAG (recombinant activating gene) is a lso found in the shark, but may have a different function from that in mammals. %%% These studies which are elucidating the immune system of the sharks, one of the most primitive vertebrates, will not only provide information on how the immune system of these organisms operates, but will give information on the probable development of the immune system of vertebrate organisms. *** ; Oh +' 0 $ H l S u m m a r y I n f o r m a t i o n ( & D h R:WWUSERTEMPLATENORMAL.DOT Abstract Una Solomon Una Solomon @ M 8I @ @ M 8I @ Microsoft Word 6.0 2 ; e = e * l l l l l l l s 1 5 U T 2 s l s l l l l l l l l k Abstract Marchalonis 9406280 Sharks belong to one of the most primitive vertebrate classes. This investigator has been studying the immune system of sharks for a number of years. The blood of these animals contains high levels of immunoglobulins, but this is IgM, a type of immunoglobulin which appears first in mammals in response to an antigen. Like human antibodies, these shark immunoglobulins show a large diversity in sequence. With the recombinant DNA technologies this laboratory was able to determine the sequence of the genes and their corresponding proteins, and found that the mechanisms for generating diversity in these immunoglobulins differs from that of mammals. In sharks the V (variable), J (joining) and C (constant) regions are not separate as in mammals, with their products coming together and combining to form different immunglobulin molecules, but exist in V,J,C clusters. Nevertheless the proteins of the shark show great diversity and a lot of similarity to the mammalian chains. More recent studies from this laboratory show that the RAG (re
