Unequal accumulation of 26S and 17S RNAs in ribosomes during spore germination in Dictyostelium discoideum

1989 ◽  
Vol 35 (9) ◽  
pp. 850-853
Author(s):  
S. Ramagopal
Keyword(s):  
Cell Differentiation ◽  
Dictyostelium Discoideum ◽  
Spore Germination ◽  
Ribosomal Proteins ◽  
Rrna Synthesis ◽  
Cellular Slime Mold ◽  
Stoichiometric Ratio ◽  
Relative Level ◽  
Ribosome Synthesis ◽  
Cellular Slime

Ribosome synthesis was studied in spores at the swelling stage and compared with freshly emerged and logarithmically growing vegetative amoebae. During the swelling stage of spore germination, ribosome synthesis was abnormal. Newly made ribosomes accumulated unequal amounts of 26S and 17S rRNAs. The stoichiometric ratio 26S:17S was 0.5 in swelling spores, compared with 0.9 in amoebae. The relative level of pre-rRNA persisting in the nucleus was apparently 2- to 3-fold higher in swelling spores than in amoebae. All of the known ribosomal proteins, except for a few, were made during the swelling stage and were associated with the newly made ribosomes in expected amounts. Analysis of the 2′-O-methyl ribose content in the newly made rRNAs suggests that methylation was defective in swelling spores. Compared with growing amoebae, the methyl content was 30 and 64% less in 26S and 17S RNAs from the swelling stage, respectively. It is suggested that undermethylation could be partly responsible for the differential accumulation of newly made 26S and 17S RNAs during the early stages of spore germination in Dictyostelium discoideum.Key words: cellular slime mold, rRNA synthesis, ribosomal proteins, methylation, cell differentiation.

Acidic ribosomal proteins of Dictyostelium discoideum that show electrophoretic similarity to Escherichia coli proteins L7 and L12

1989 ◽  
Vol 67 (10) ◽  
pp. 712-718 ◽  
Author(s):  
S. Ramagopal
Keyword(s):  
Escherichia Coli ◽  
Dictyostelium Discoideum ◽  
Gel Electrophoresis ◽  
Ribosomal Proteins ◽  
Sodium Dodecyl ◽  
Slime Mold ◽  
Cellular Slime Mold ◽  
Two Dimensional ◽  
Cellular Slime ◽  
Acidic Proteins

This study documents the presence of three acidic proteins, A1 (pI 4.95), A2 (pI 4.85), and A3 (pI 4.70), in Dictyostelium discoideum ribosomes. All three proteins showed an apparent molecular mass of 13 000 by two-dimensional, sodium dodecyl sulfate gel electrophoresis. They were selectively released by treatment of ribosomes with 50% ethanol – 1 M NH4Cl. The amino acid compositions of A1, A2, and A3 were identical and indicated a predominant amount of alanine. All the above properties are shared by Escherichia coli proteins L7 and L12 and acidic ribosomal proteins in many eukaryotes. Unlike other eukaryotic systems, the acidic proteins of D. discoideum were found associated with the 40S rather than the 60S ribosomal subunit. Acidic proteins analogous in size and electrophoretic mobility to those of D. discoideum were also detected in several other cellular slime mold strains. Not one of the cellular slime mold acidic proteins reacted with antibodies to E. coli proteins L7 and L12 in immunodiffusion tests. In D. discoideum, the distribution of acidic proteins was altered during development. Amoebae contained all three proteins. In spores, A, was absent and the relative amounts of A2 and A3 were lower than in amoebae. In addition, nine other acidic ribosomal proteins exhibited differences between vegetative amoebae and spores.Key words: acidic ribosomal proteins, development, cellular slime mold, L7 and L12 proteins, two-dimensional gel electrophoresis.

scholarly journals Partial structure of a spore germination inhibitor from a cellular slime mold, Dictyostelium discoideum.

1975 ◽  
Vol 39 (10) ◽  
pp. 1929-1932 ◽  
Author(s):  
Yoshi-Masa TANAKA ◽  
Yohichi HASHIMOTO ◽  
Kaichiro YANAGISAWA ◽  
Hiroshi ABE ◽  
Masaaki UCHIYAMA
Keyword(s):  
Dictyostelium Discoideum ◽  
Spore Germination ◽  
Slime Mold ◽  
Cellular Slime Mold ◽  
Partial Structure ◽  
Germination Inhibitor ◽  
Slime Mold Dictyostelium Discoideum ◽  
Cellular Slime

Synthesis of a ribosome-bound translatable poly(A)− mRNA during spore germination in Dictyostelium discoideum

1989 ◽  
Vol 35 (5) ◽  
pp. 573-577
Author(s):  
S. Ramagopal
Keyword(s):  
Dictyostelium Discoideum ◽  
Spore Germination ◽  
Gel Electrophoresis ◽  
Rna Synthesis ◽  
In Vitro Translation ◽  
Cellular Slime Mold ◽  
Free System ◽  
Cellular Slime

A distinct poly(A)− RNA sedimenting around 10–12S was identified during spore germination in Dictyostelium discoideum. Activated spores were labeled with [3H]uracil and the poly(A)− RNA was purified from ribosomal particles for analysis. In the spore swelling stage, 40 to 50% of the newly synthesized poly(A)− RNA was 10–12S RNA. This fraction diminished to one-half or one-fourth depending on the labeling period at the stage of amoeba emergence. The 10–12S RNA was associated with both monosomes and polysomes in vivo. Translation in a wheat germ cell-free system and gel electrophoresis demonstrated that the 10–12S RNA coded for a number of polypeptides, some of which were also represented among the in vitro products of poly(A)+ RNA. However, there were seven unique polypeptides (37.5, 28.2, 27.5, 23, 17.7, 17, and 14.2 kilodaltons) encoded exclusively by 10–12S RNA.Key words: cellular slime mold, RNA synthesis, development, poly(A)− mRNA, in vitro translation.

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