An evolutionary ‘intermediate state’ of mitochondrial translation systems found in Trichinella species of parasitic nematodes: co-evolution of tRNA and EF-Tu

EF-Tu delivers aminoacyl-tRNAs to ribosomes in the translation system. However, unusual truncations found in some animal mitochondrial tRNAs seem to prevent recognition by a canonical EF-Tu. We showed previously that the chromadorean nematode has two distinct EF-Tus, one of which (EF-Tu1) binds only to T-armless aminoacyl-tRNAs and the other (EF-Tu2) binds to D-armless Ser-tRNAs. Neither of the EF-Tus can bind to canonical cloverleaf tRNAs. In this study, by analyzing the translation system of enoplean nematode Trichinella species, we address how EF-Tus and tRNAs have evolved from the canonical structures toward those of the chromadorean translation system. Trichinella mitochondria possess three types of tRNAs: cloverleaf tRNAs, which do not exist in chromadorean nematode mitochondria; T-armless tRNAs; and D-armless tRNAs. We found two mitochondrial EF-Tu species, EF-Tu1 and EF-Tu2, in Trichinella britovi. T.britovi EF-Tu2 could bind to only D-armless Ser-tRNA, as Caenorhabditis elegans EF-Tu2 does. In contrast to the case of C.elegans EF-Tu1, however, T.britovi EF-Tu1 bound to all three types of tRNA present in Trichinella mitochondria. These results suggest that Trichinella mitochondrial translation system, and particularly the tRNA-binding specificity of EF-Tu1, could be an intermediate state between the canonical system and the chromadorean nematode mitochondrial system

Teacher Unionism: An Assessment of Teachers' Motives for Joining Unions

154 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.This dissertation attempts to enter the thicket of the motivational structure of individual teachers who join unions as a necessary step toward a better understanding of the problems facing American teacher unionism today. The purpose of this study is as follows: (1) to theoretically identify teachers' motives for joining unions; (2) to empirically identify teachers' motives for joining unions; (3) to investigate the relative importance of the empirically identified motives; (4) to assess the relative importance of the functions of teacher organizations (professional, economic, political) in terms of their influence on teachers' joining unions; and (5) to assess whether or not motives for joining unions differ between teachers with different union affiliations.Survey instruments were designed and distributed to local union members of the National Education Association (NEA) and the American Federation of Teachers (AFT) in central Illinois school districts.The findings in this study are based on usable completed questionnaires returned from 193 union teachers. The 193 returns represent about 38 percent of the 510 questionnaires distributed.The major findings can be summarized as follows: (1) Teachers surveyed put their highest priority upon job security or protection through union membership. (2) There is a significant difference between the NEA and the AFT teachers in terms of what they are seeking in union membership: the NEA teachers are concerned with both formal and informal types of job security such as "higher salary" and the "union's good legal protection," while the AFT teachers are concerned with informal types of job security through the union's direct economic services such as the "credit union" and "discount product services." (3) There are not any differences between the NEA and the AFT teachers in the variables "political motives" and "professional motives," two aspects of union activities in which each teacher union has claimed its superiority to the other and has emphasized its differences.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD