FIGURE 6.

Secondary ion images of (A) vegetative cells (D2 Pulse and D4 Chase) and of an akinete (D20 Chase) of A. ovalisporum and (B) corresponding filaments. Images are based on NanoSIMS analysis. ¹³C bicarbonate was provided to akinete-induced cultures for the first 2 days and chased with ¹²C bicarbonate for additional 18 days during which akinete differentiation occurred. Images in (A) represent transverse section of vegetative cells or an akinete. Note size differences between vegetative cells and akinetes. (A) The upper row images represent ¹³C to ¹²C ratio. Note the white arrows in D4 Chase image indicating new synthesis of presumable cyanophycin. The D20 Chase image indicates reduced ¹³C signal (¹³C to ¹²C ratio near the background level) which masks the location of an akinete (presented by a dotted circle which was allocated based on the overlay with the corresponding ¹²C¹⁴N ion image). The lower row images show the localization of N-enriched compounds based on the ¹²C¹⁴N ion. Bar scales = 2 μm. Color scales for images is provided. The graphs at the lower row show the relative distribution of ¹³C to ¹²C ratio of more than 2000 pixels composed each cellular image, indicating ¹³C dilution during the chase period. (B) The upper row images represent ¹³C to ¹²C ratio in several filaments. Note the D20 Chase image with substantially reduced ¹³C signal (¹³C-to-¹²C ratio near the background level) which masks the location of the filaments. The lower row images show the localization of N-enriched compounds in the same filaments based on the ¹²C¹⁴N ion. Note the localization of high ¹²C¹⁴N ion signal in D20 Chase image, presumably presented cyanophycin (indicated by white arrows) in free akinetes and in attached akinetes. Bar scales = 4 μm. Color scales for images is provided.