Amphibian ribosomal ribonucleic acids

Abstract

1. The larger rRNA molecules of different species of amphibia do not all have the same mobility on polyacrylamide gels, and the difference appears to be one between the Anuran and Urodele amphibia. 2. Alteration of conditions of electrophoresis so as to distinguish between differences of conformation and molecular weight does not affect the results. 3. The mobility on gel electrophoresis of the rRNA precursor in two species of amphibia is similar, although the intermediate processing products differ. 4. It is suggested that the mobility differences observed represent differences of molecular weight, and are an example of the variability of the products of transcription and processing of rRNA genes in two amphibian genera.

Unusual Features of the Structure of the Major RNA Component of the Larger Subribosomal Particle of the Rabbit Reticulocyte

“…Fractions (1 ml)were collected and E 260 was measured against the appropriate buffer as blank. Fractions (12)(13)(14)(15)(16)(17)(18)(19)(20) were combined (9 ml) and they accounted for ca. 55% of the total RNA.…”

“…"Non conserved" (~) denotes that part of the RNA moiety that may vary from one class to another yet may be largely the same for species within the same class, e.g. amphibians [13,17]. doh schemes for RNA of other classes are according to the model proposed for rabbit RNA.…”

“…Fractions (IS ml) were then collected and E 260 measured. The profile of E 260 vs. fraction number revealed two sharp peaks corresponding to the smaller (fractions [14][15][16][17][18][19] and larger (fractions [23][24][25][26][27] subparticles. The subparticles were precipitated with 2 vols ethanol, left at _12°C overnight, and the sediment was resuspended in 1 mM MgCl2 0.01 M phosphate buffer pH 7.0.…”

Lengths and patterns of transcriptional units in the amplified nucleoli of oocytes of Xenopus laevis

“…10a), in agreement with values obtained with similar gel systems (e.g., Loening et a !. , 1969 ;Rogers and Klein , 1972 ;Bird eta !. , 1973;Scheer, 1973 ;Hagenbüchle eta!.…”

Structural characteristics of genome organization in amphibians: Differential staining of chromosomes and DNA structure

“…In mammals it is greater than the sum of 18S and 28S by almost 80%, while in polikilotherms the difference is only 25-50%. The size of 28S RNA in amphibians is much smaller (1.39-1.55x106 daltons) than in birds and mammals (1.58x106 and 1.71x106 daltons respectively), while the size of 18S is approximately the same (0.7x106 daltons) (Loening 1968;Rogers and Klein 1972). It should be noted that the molecular weight of 28S RNA varies among species of the two Amphibia orders: 28S RNA in X. laevis is larger than in Triturus cristatus and Plethodon cinereus (1.55x106, 1.39x106 and 1.45x 106 daltons respectively) (Rogers and Klein 1972).…”