Gel Diffusion Studies on Serotype and Serotype Transformation in Paramecium

Abstract

SUMMARY: Antigens G and E of stock 28 variety 2 of Paramecium aurelia show cross-reactions with their respective antisera in immobilization and gel diffusion tests. In immobilization tests the anti-E serum P, no. 132, shows the strongest cross-reaction; in gel diffusion tests the anti-G serum P, no. 130, cross reacts more strongly. During serotype transformation of type G protozoa to type E, the increase of the E antigen and the disappearance of the G antigen were followed by the gel diffusion technique. However, because of the peculiar cross-reactions of these two antigens, only the increase of the new (E) antigen was studied quantitatively by this technique. No reliable measurements of the loss of the old (G) antigen were obtained. The results indicate that during transformation the amount of the new antigen increased exponentially.Within a given stock of Paramecium azcrelia a number of clones representing different antigenic types or serotypes may be obtained. Each clone is immobilized by an appropriate dilution of homologous antiserum made against protozoa of its own serotype and unaffected by similar dilutions of sera made against other serotypes. Studies of the immobilization antigens of Paramecium by Sonneborn and others have revealed that they are determined by a complex interaction of three factors: the environment, a system of cytoplasmic inheritance, and nuclear genes (review; see Beale, 1957). Changes in the environment often induce a transformation from one serotype to another. Often the different serotypes of a stock are stable under the same environmental conditions. Under such circumstances crosses between the different serotypes reveal that the differences are maintained by a system of cytoplasmic inheritance. The serotypes which can be manifested, their specific properties and also their stability have been shown to vary from stock to stock, and to be under the control of nuclear genes.The data are consistent with the idea that there is a separate primary genic locus for each serotype, a locus which influences whether the serotype in Paramecium aurelia can be expressed, its stability, and its immunological specificity. More than one locus, however, may be involved in stability. Normally, the effect of only one primary locus is evidenced a t any one time, i.e. only one antigen is detectable. In most of the cases studied any one of a number of equally competent loci may come to expression under a particular set of conditions. Once a type is expressed, however, the continued expression of that locus rather than the others is transmitted hereditarily through the Spring Harbor,

Immunogenetic Analysis of Proteins of Paramecium Ii. Coexistence of Two Immobilization Antigens Within Animals of a Single Serotype

“…It can be seen that while a culture might indeed be composed of animals with secondary antigens internally, these might be overlooked were not the appropriate sera at hand (BALBINDER and PREER 1959). Of the 21 sera available to US, only six regularly precipitated two bands.…”