Table 1.

Expression data for candidate reference genes from Pseudo-nitzschia multiseries ( Ps-n ) cDNA microarray analysis ^a

		Fold change b
		Stationary versus late-exponential phase
Ps-n NR Identifier	JGI Ps-n Genome hit	Non-axenic	Non-axenic	Axenic	Predicted gene product
	Scaffold:Start-End	Expt. 1	Expt. 2	Expt.
53B6	41:203449-205143	1.05 ± 0.01	1.04 ± 0.05	1.05 ± 0.03	JmjC-domain family protein (JmjC)
45E3	55:316954-329784	1.10 ± 0.02	1.24 ± 0.07	1.36 ± 0.05	Dynein heavy chain, cytosolic
177F1	198:180888-181958	1.05 ± 0.02	0.93 ± 0.01	0.81 ± 0.01	Histone H3
PSN0918	2485:4610-6293	1.30 ± 0.00	1.29 ± 0.37	0.99 ± 0.01	Cyclophilin
PSN0001	10:398258-400584	1.37 ± 0.10	1.19 ± 0.07	1.10 ± 0.17	Elongation factor 1-alpha (EF-1α)
PSN0547	210:148023-149837	0.90 ± 0.08	0.78 ± 0.05	1.26 ± 0.03	Phosphoglycerate kinase (PGK)
PSN1327	890:26709-27681	1.00 ± 0.03	1.07 ± 0.00	1.24 ± 0.03	Elongation initiation factor 2 (eIF-2)
PSN0332	2:525315-527491	1.13 ± 0.05	1.29 ± 0.03	1.19 ± 0.17	ATPase with AAA domain
PSN0032	18:343323-346000	0.74 ± 0.04	0.68 ± 0.06	0.44 ± 0.03c	Ubiquitin
PSN1138	68:114178-115516	0.87 ± 0.08	0.92 ± 0.09	1.73 ± 0.23c	Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)

^a Potential reference genes for RT-qPCR studies were selected based on their stability in the microarray results or their use as controls in previous studies.

^bThe fold-change data presented in Table 1 represents the average differences across all of the cDNA clones that were printed on the array for each transcript. As follows, the number of independent cDNA clones for each transcript was: 53B6 (1), 45E3 (1), 177F1 (1), PSN0918 (1), PSN0001 (58), PSN0547 (2), PSN1327 (1), PSN0032 (7), PSN0332 (2), PSN1138 (6). Each clone was printed in duplicate on array. 18s not printed on array.

^cTranscript levels showed statistically significant differences between samples.