Table II.

Calculation of the Rubisco fraction in both the pyrenoid and the stroma of wild-type cells and strain 18–7G grown on acetate

Strain	Immunogold Density			Rubisco in Pyrenoid
	Pyrenoid	Stroma	Cytoplasm
		particles mm−2		%
Wild type	149  ± 63	6.2  ± 1.5	3.8  ± 1.7	80
18–7G	N.A.	1.3  ± 0.9	1.6  ± 0.6	N.A.

Both cell lines were grown in moderate light (150 μmol mm⁻² s⁻¹) on acetate medium. To quantitate the number of immunogold particles in the stroma and in the pyrenoid the method described in the legend to Table I was employed. Because the pyrenoid is absent from 18–7G, the number of particles in the pyrenoid is not applicable (N.A.). Ten samples of each strain were sampled. The data shown are the averages ± sd.