Range 
estimated ~1,000: predicted by Gaussian fitting 275 Ribosomes/cell

Organism 
Bacteria Spiroplasma melliferum 
Reference 
Ortiz JO, Förster F, Kürner J, Linaroudis AA, Baumeister W. Mapping 70S ribosomes in intact cells by cryoelectron tomography and pattern recognition. J Struct Biol. 2006 Nov156(2):33441 DOI: 10.1016/j.jsb.2006.04.014 value of ~1,000 ribosomes per cell p.339 right column. Value of 275 ribosomes per cell p.338 right column and note beneath table 1. p.339 left column bottom paragraphPubMed ID16857386

Method 
Cryoelectron tomography (CET) and Scaling index based segmentation (SIBS) 
Comments 
Value of ~1,000 ribosomes per cell: P.339 right column: "Extrapolating the predicted ribosomal density to a whole cell, typically three to four times larger in volume than the analyzed portion, [researchers] can estimate that a Spiroplasma cell has a total complement of approximately 1000 ribosomes." Value of 275 ribosomes per cell: P.338 right column: "Considering that 275 ribosomes were predicted by Gaussian fitting of experimental crosscorrelation peaks, [investigators] estimate that ca. 30% of all SIBS [Scaling index based segmentation] complexes are not ribosomes." P.338 note beneath table 1: "Gaussian fitting of the experimental distribution of CCCs [crosscorrelation coefficients] predicts 275 ribosomes for the tomogram shown in Fig. 2." P.339 left column bottom paragraph: "Assuming that each 70S ribosome has a volume of 3400 nm^3 (Zhu et al., 1997), the predicted 275 ribosomes occupy approximately 5% of the cellular volume." 
Entered by 
Uri M 
ID 
108945 