. 2017 Oct 13;9(10):322. doi: 10.3390/toxins9100322

Table 4.

Summary of studies on environmental regulation of saxitoxins transporters expression in different cyanobacterial species.

Organism	Factor	Effect on Extracellular STX Release	Effect on the Expression of STX Transporters		Reference
Organism	Factor	Effect on Extracellular STX Release	sxtM	sxtPer	Reference
Aphanizomenon gracile	Temperature (12°C and 30°C vs. 23 °C)	4-fold higher at 30 °C than at 23 °C	Upregulation (2.9–4.3X) at 30 °C Upregulation (3.6–3.8X) at 12 °C	Upregulation (2.1X) at 30 °C	This study
Aphanizomenon gracile	Nitrate (absence—BG11₀- vs. presence—BG11-)	4-fold higher without nitrate (BG11₀)	NS	NS	This study
Anabaena circinalis	Ph (9 vs. 7)	Higher at pH 9 (exact value not provided)	Downregulation at pH 9 (59X) vs. pH 7	NP	[18]
Anabaena circinalis	Na⁺ (10 mM vs. 1.3 mM ¹)	Higher at 10 mM (exact value not provided)	Downregulation at 10 mM (2.7X) vs. 1.3 mM	NP	[18]
Cylindrospermopsis raciborskii	pH (9 vs. 7)	Higher at pH 9 (exact value not provided)	Upregulation at pH = 9 (24X) vs. pH 7	NP	[18]
Cylindrospermopsis raciborskii	Na⁺ (10 mM vs. 1.3 mM ¹)	Higher at 10 mM (exact value not provided)	Upregulation at 10 mM (2.7X) vs. 1.3 mM	NP	[18]

¹ 1.3 mM is the sodium concentration in Jaworski’s medium used as control. NS, differences not statistically significant; NP, gene not present in the cited species.