Ronald D. Brown

Synthesis and maturation of cytoplasmic ribosomal RNA in Euglena gracilis

Abstract A pathway is described for the synthesis and maturation of cytoplasmic ribosomal RNA in Euglena gracilis. The primary product of transcription of the ribosomal genes has a molecular weight of 3.5 × 106. This molecule is cleaved through a series of identifiable intermediates to the 1.35 × 106 and 0.85 × 106 molecular weight mature ribosomal RNA molecules. From our data it is possible to map the 0.85 × 106 molecular weight sequence as being on the 5′ end of the 3.5 × 106 molecular weight precursor. It is also possible to calculate the chain growth-rate of the ribosomal RNA precursor as 12.5 nucleotides/second at 25 °C.

FT-MW AND MILLIMETER WAVE SPECTROSCOPY OF PANHs: PHENANTHRIDINE, ACRIDINE, AND 1,10-PHENANTHROLINE

The pure rotational spectra of phenanthridine, acridine, and 1,10-phenanthroline, small polycyclic aromatic nitrogen heterocycle molecules (PANHs), have been measured and assigned from 2 to 85 GHz. An initial spectral assignment, guided by ab initio molecular orbital predictions, employed broadband Stark modulated millimeter wave absorption spectroscopy of a supersonic rotationally cold molecular beam, yielding a preliminary set of rotational and centrifugal distortion constants. Subsequent spectral analysis employed Fourier transform microwave (FT-MW) spectroscopy of a supersonic rotationally cold molecular beam. The extremely high spectral resolution of the FT-MW instrument yielded improved rotational constants and centrifugal distortion constants, together with nitrogen quadrupole coupling constants, for all three species. Density functional theory (DFT) calculations at the B3LYP level of theory employing the cc-pVTZ and 6-311+G** basis sets are shown to closely predict rotational constants and to be useful in predicting quadrupole coupling constants and dipole moments for such PANH species. The data presented here will be useful for deep radio astronomical searches for PANHs employing large radio telescopes.

The isolation of Euglena gracilis chloroplasts uncontaminated by nuclear DNA

Abstract A method is described for the rapid isolation of Euglena chloroplasts and chloroplast DNA free of contamination by nuclear DNA.

Microwave spectrum of the major gas-phase tautomer of thymine

The microwave spectra of the nucleic acid base thymine and of two of its mono-deuteriated species have been analysed indicating that the diketo tautomer is the most abundant form in the gas phase.

The generation and microwave spectrum of propadienethione, H2CCCS

The third member of the cumulenethione series, H2CnS, propadienethione, has been produced by pyrolysis of cyclopenteno-1,2,3-thiadiazole and detected by microwave spectroscopy which provided rotational parameters for the 32S and 34S isotopomers, the dipole moment [2.064(8) Debye], and an indication that propadienethione is a planar molecule of C2v symmetry.

An analysis of the degree of homology between 28S rRNA from Xenopus laevis and Xenopus mulleri

Summary Ribosomal 28S RNA labeled with 32PO4 was isolated from Xenopus laevis and Xenopus mulleri . The ribonuclease digests of the RNAs were then analyzed and compared by oligonucleotide homochromatography and fingerprinting. No differences could be detected between these molecules from the two Xenopus species in the fingerprint or oligonucleotide patterns. The 28S rRNA of HeLa cells was shown to contain sequences which differ greatly from the Xenopus .

The inversion spectrum of cyanamide

Twelve Q branch lines and four R branch lines in the inversion spectrum of cyanamide are reported for the first time together with the µc component of the dipole moment of cyanamide and a double-minimum potential function that describes the inversion motion.

[15b] The preparation of RNA-directed DNA polymerase from ovaries of Xenopus laevis

Publisher Summary This chapter describes the preparation of RNA-Directed DNA polymerase from ovaries of Xenopus laevi . Young oocytes of Xenopus laevis synthesize DNA that corresponds to a selected portion of the chromosome—the genes coding for ribosomal RNA. Several assays have been used during the isolation of this RNA-directed DNA polymerase activity. First, the synthesis of DNA using native calf thymus DNA as a template has been routinely used during the enzyme purification. Second, enzyme fractions have been assayed for their ability to use the artificial homopolymers poly rA:dT 10 and poly dA:dT 10 , as templates. It has been suggested that the preferential use of poly rA:dT 10 as a template is a characteristic trait of RNA-directed DNA-polymerases. Third, as only very small amounts of the supposed natural template can be isolated, an indirect assay has been developed that measures the use of the long transcript as a template by its binding to Millipore filters.