Protozoa of the family Trypanosomatidae are pathogenic agents of human and animal diseases. Fine structure, compaction pattern, and histone content of the soluble chromatin were investigated in procyclic forms of Trypanosoma cruzi (Chagas disease, S. America) and T. brucei brucei (Nagana disease, Africa) in comparison with rat liver chromatin. At low ionic strength chromatin was present as nucleosome filaments. Condensation into compact fibers (solenoid) was complete for rat chromatin at 100 mM salt concentration while chromatin of T. cruzi showed less condensation (tangle formation), and that of T.b. brucei did barely condense under identical experimental conditions. In general, the nucleosomes of trypanosomes, especially T.b. brucei, seemed to be less regularly arranged than those of the higher eukaryote. Addition of histone H1-containing fractions of rat liver chromatin increased the compaction of T. cruzi chromatin but had no influence on T.b. brucei chromatin. SDS-polyacrylamide gel electrophoresis revealed histone H1 and the 4 core histones in rat liver chromatin. Neither in T. cruzi nor T.b. brucei were proteins identical to rat histone H1 present. Differences existed also in molecular weight of core histones between rat and trypanosomes, as well as between T. cruzi and T.b. brucei. These differences might explain species-specific differences in the fine structural organization and compaction pattern of the chromatin of the rat, T. cruzi, and T.b. brucei.

In A. thaliana the translation elongation factor EF-1 alpha is encoded by a small multigenic family of four members (A1-A4). The A1 gene promoter has been dissected and examined in a transient expression system using the GUS reporter gene. Deletion analysis has shown that several elements are involved in the activation process. One cis-acting domain, the TEF 1 box, has been accurately mapped 100 bp upstream of the transcription initiation site. This domain is the target for trans-acting factors identified in nuclear extracts prepared from A. thaliana. Homologies are found between the TEF 1 box and sequences present at the same location within the A2, A3 and A4 promoters. This observation, together with those obtained from gel retardation assays performed using DNA fragments from the A4 promoter, suggest that the activation process mediated by the TEF 1 element is conserved among the A. thaliana EF-1 alpha genes. Analysis of nearly full length cDNA clones has shown that in addition to a single intron located within the coding region, the A1 gene contains a second intron located within the 5' non coding region. Such an intron is also present within the A2, A3 and A4 genes. This 5' intervening sequence appears to be essential to obtain a maximum GUS activity driven by the A1 gene promoter.

Two RNA . protein complexes were isolated from duck erythroblast postribosomal supernatants. Their nominal sedimentation values on sucrose gradients are 12 S and 20 s, respectively. The 12-S particle contains a 4-6 S RNA, in the 20-S particle a 9-S RNA is found. This 9-S RNA is shown to direct the synthesis of all duck globin chains in a cell-free, messenger RNA-dependent protein-synthesizing system.The protein moiety of these ribosome-free particles is described and compared with the proteins found in the mRNA * protein complex liberated by EDTA from polyribosomes. We show that in the free-cytoplasmic particles no protein can be found which is identical to any of the polypeptides associated with polyribosomal mRNA. Some of these proteins are phosphorylated and contain phosphoserine. The electrophoretic patterns of phosphorylated proteins from the two globin mRNA-containing complexes differ, as do those of the unlabelled polypeptides. We conclude that the mRNA-associated protein population is exchanged when the mRNA enters the translation machinery.The possible role of the RNA-associated proteins in the post-transcriptional and translational control of eukaryotic protein synthesis is discussed.On the basis of experiments concerning the nucleic acid metabolism in duck immature red cells and in HeLa cells we postulated [I] that the regulation of gene expression in animal cells resides in a multistep process including the three principal phases of cellular information transfer : (a) the synthesis in the nucleus of giant precursor molecules (pre-mRNA) to messenger RNA (mRNA), (b) the processing of the pre-mRNA which gives rise ultimately to mRNA that is transported (and stored) in the cytoplasm, (c) the translation of the mRNA into protein. This regulational system governing the multiple steps involved in synthesis, processing and translation of mRNA was termed "Cascade Regulation" [l -31. Evidence that the giant nuclear RNA of molecular weight more than 5~1 0~is an informative precursor to mRNA was given recently by Imaizumi et al. [5] who showed conclusively by molecular hybridization that these RNA molecules, isolated from duck erythroblasts, contain sequences homologous to polyribosomal 9-S duck globin mRNA. However, the processing of pre-mRNA and the transfer of mRNA to the cytoplam are still obscure.Abbreviations. pre-mRNA, precursor molecule to mRNA; mRNA * protein, messenger ribonucleoprotein complex. strate that newly synthesized mRNA appears in the cytoplasm first free from ribosomes but associated with proteins in the form of ribonucleoprotein complexes. Some mRNA types then associate with ribosomes; others may be degraded without being translated.

Bean (Phaseolus vulgaris), an important component in the diet of people in developing countries, has low levels of the essential amino acid, methionine. We have attempted to correct this deficiency by introducing a transgene coding for a methioninerich storage albumin from the Brazil nut via biolistic methods. The transgene's coding sequence was driven by a doubled 35S CaMV promoter and AMV enhancer sequences. The transgene was stable and correctly expressed in homozygous R 2 to R 5 seeds. In two of the five transgenic lines the methionine content was significantly increased (14 and 23%) over the values found in untransformed plants.