Synthesis of a 3-methyluridine phosphoramidite to investigate the role of methylation in a ribosomal RNA hairpin.

The synthesis of a 5'-O-BzH-2'-O-ACE-protected-3-methyluridine phosphoramidite is reported [BzH, benzhydryloxy-bis(trimethylsilyloxy)silyl; ACE, bis(2-acetoxyethoxy)methyl]. The phosphoramidite was employed in solid-phase RNA synthesis to generate a series of RNA hairpins containing single or multiple modifications, including the common nucleoside pseudouridine. Three 19-nucleotide hairpin RNAs that represent the 1920-loop region (G(1906)-C(1924)) of Escherichia coli 23S ribosomal RNA were generated. Modifications were present at positions 1911, 1915, and 1917. The stabilities and structures of the three RNAs were examined by using thermal melting, circular dichroism, and NMR spectroscopy     

Number and pattern of association of chromonemata in the chromosomes of Tradescantia

Summary Analysis of reconstructions, prepared from electron micrographs of successive longitudinal serial sections, has led to the conclusion that the somatic telophase chromosome of Tradescantia paludosa contains four cytologically separable chromonemata. The four represent a pair of pairs, that is, two diplospiremes — one with its two chromonemata arranged helically in dextrorse relationship, and the other with its two in sinistrorse relationship — which are associated to form a tetraspireme. During anaphase and telophase the tetraspireme constitutes the chromosome; during prophase and metaphase the tetraspireme represents one of the two chromatids of the chromosome, which is accordingly an octospireme in terms of the number of cytologically identifiable chromonemata. Loose intertwining of the two tetraspiremes during late prophase accounts for the so-called relational coiling.This paper is dedicated to Professor Hans Bauer on his sixtieth birthday anniversary in appreciation of his contributions to the development of modern cytology.The work reported here was supported in part by Research Grants GM-10499 from the National Institutes of Health, U.S. Public Health Service, and GB-290 from the National Science Foundation, and in part by a NATO fellowship awarded to E. Sparvoli by the Italian National Council of Research.     

Myotonia congenita (Thomsen's disease) excluded from the region of the myotonic dystrophy locus on chromosome 19

Summary Linkage analysis has been carried out in six German families with autosomal dominantly inherited myotonia congenita (Thomsen's disease) using five chromosome 19 markers known to be linked to the gene for myotonic dystrophy (DM). Two of the markers, APOC1 and APOC2, are tightly linked to DM. Close linkage between these markers and myotonia congenita (MC) has been excluded to a distance of 9cM (z=-2.158). These data support the clinical suggestion that MC and DM are non-allelic disorders.