TABLE 1.

Characteristics of human artificial chromosomes

Input DNA	Cell line	Characteristic
		Relative sizea	CENP-Eb	Mitotic stabilityc	Centromered	Telomeree
Strategy 1
DXZ1	X-1	Small	+	+	Acquisition	−
	X-2	Small	+	−	ND	ND
	X-3	Small	+	+	Acquisition	−
	X-4	Medium	+	+	De novo	−
	X-5	Medium	+	+	De novo	−
	X-6	Small	+	ND	Acquisition	−
D17Z1	17-1	Small	+	+	De novo	−
	17-2	Small	+	+	De novo	−
	17-3	Medium	+	ND	De novo	−
	17-4	Medium	+	ND	De novo	−
Strategy 2
D17Z1	PF2.6	Small	+	+	De novo	+
	PF2.7	Small	+	+	De novo	−
	17-15	Large	+	+	De novo	+

^aRelative size was determined by DAPI staining, and artificial chromosomes were grouped into small, medium, and large categories. Small artificial chromosomes were estimated to be ∼15 Mb or less, medium artificial chromosomes were estimated to be between 15 and 30 Mb, and large artificial chromosomes were estimated to be larger than 30 Mb.

^bImmunostaining for the presence of anti-CENP-E antibodies on the artificial chromosome (16).

^cMitotic stability was measured as described in Materials and Methods. Mitotically stable artificial chromosomes were retained at a rate of 98.6 to 100% per cell division, calculated as described previously (16). ND, not done.

^dArtificial chromosomes were tested for the acquisition of non-input alpha satellite DNA sequences (Materials and Methods).

^eArtificial chromosomes were assayed for the presence of functional telomeres. Artificial chromosomes constructed from circular input DNA (in cell lines X-1 to 17-4) did not acquire telomere sequences as demonstrated by FISH. The presence of functional telomeres in artificial chromosomes in which telomere sequences were included in the input constructs (PF2.6 and PF2.7) was confirmed by gamma irradiation and pulsed-field gel analysis.