. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. GENETIC BASIS FOR RESORPT1ON IN BOTRYLLUS 343 lished with colonies that were both homozygous at the Fu/HC locus [ AA vs. AA (4, 13)], which implied the involvement of additional genetic elements. To further analyze this possibility, we established 121 pairs of chimeric partners by fusions of relatives from four generations within a pedigree, all homozygotes (AA line) at their Fu/HC haplotype (13). This was carried out by self- and defined-crosses done in the laboratory on two outbred founder colonies (each AB at the fus
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. GENETIC BASIS FOR RESORPT1ON IN BOTRYLLUS 343 lished with colonies that were both homozygous at the Fu/HC locus [ AA vs. AA (4, 13)], which implied the involvement of additional genetic elements. To further analyze this possibility, we established 121 pairs of chimeric partners by fusions of relatives from four generations within a pedigree, all homozygotes (AA line) at their Fu/HC haplotype (13). This was carried out by self- and defined-crosses done in the laboratory on two outbred founder colonies (each AB at the fusibility locus) which were taken from the field. We found that the re- sorption phenomenon within each generation of colonies is characterized by a linear hierarchy which is expressed by the existence of at least five intermediate hierarchial rungs ( colony A repeatedly resorbs colonies, B. C. D. E; colony B resorbs colonies C, D, E: and so on). Analysis of resorption hierarchies between generations revealed that mother colonies always resorbed their self-crossed off- spring. Colonies low in the hierarchy within a specific generation reproducibly resorbed the self-crossed offspring of a superior kin. Chimeras between denned-crossed off- spring and self-crossed offspring of different generations revealed nontransitive hierarchies ( colony A resorbs colony B; colony B resorbs colony C: but colony C resorbs colony A) in the resorption; these were correlated with the relative position of each colony in the linear hierarchy established within each generation (major results are schematically illustrated in Fig. 1). In this essay I speculate on the genetic framework un- derlying the resorption phenomenon. I propose that al- logeneic resorption in Botryllus is elicited and controlled by a polymorphic, ladder-like, tri-level hierarchial system of histocompatibility elements (Fig. 1; Table I). Hierarchy Generation. Figure 1. A schematic illustration of the hierarchies in the res
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
