22 NIR Imaging
541
exhibit protein distributions, they showed different variation patterns depending on
the protein secondary structures. The α-helix component in the egg yolk increased
with egg development (Fig. 22.21b), but the protein concentration with β-sheet structure, on the other hand, became higher on day 1 and JBH than during the intermediate
period (Fig. 22.21c). Monroy et al. investigated the pathway of yolk utilization during
egg development using a radioactive element for imaging [47]. They revealed that the
synthesis of embryonic proteins from the yolk and its utilization rate was different
depending on each developmental stage [47]. That is, the yolk has different roles at
each developmental stage, and NIR imaging might capture the metabolic changes
depending on the phases, in situ, without labeling. Figure 22.21d shows the distribution of unsaturated fatty acids constructed by the second derivative intensity at
4666 cm
−1 [41]. The highlighting of oil droplets and egg membrane in this image
indicates the existence of the unsaturated fatty acids in these embryonic structures.
22.6.3 High-Speed NIR Imaging of Fish Egg Embryogenesis
For high-speed NIR imaging, the Compovision system was used. Figure 22.22
depicts visible images of the fish eggs in the same day series (a), and NIR images
constructed using second derivative intensities and chemometrics (b)–(f) in the 1460–
1767 nm (6850–5660 cm
−1 ) region. In Fig. 22.22b made by the band at 1767 nm
(5660 cm
−1 ), which was assigned to the first overtone of C–H stretching mode of CH 2
groups in hydrocarbons and aliphatic compounds [40, 48, 49], clearly depicts the egg
membrane and oil droplets. Since cell membrane generally has a phospholipid bilayer
structure with many CH 2 groups, the structure is expected to be visualized. Furthermore, after third day, eye structures were also depicted using the band. The images
of the first overtone of C–H stretching band in CH 2 groups at 1716 nm (5828 cm
−1 )
are shown in Fig. 22.22c [40, 41, 49]. The band position of the first overtone of
C-H stretching in unsaturated fatty acids shifts from 1725 nm (5797 cm
−1 ) to 1709–
1717 nm (5851–5824 cm
−1 ) [41, 50]. Fish eggs contain much polyunsaturated fatty
acids such as docosahexaenoic acid and eicosapentaenoic acid. Therefore, Fig. 22.22c
can be interpreted to exhibit the distribution of unsaturated fatty acids. That is, the
distributions of different fatty acids depending on the degree of unsaturation can be
selectively visualized. The band intensity at 1564 nm (6394 cm
−1 ) due to the first
overtone of N–H stretching mode of amide groups was used to prepare Fig. 22.22d
[40, 45]. The membrane proteins were expected to make clear the egg membrane.
The heterogeneous highlight within oil droplets in Fig. 22.22d overlapped with the
part in Fig. 22.22b. This part may show the lipoprotein distribution in which lipids
present in plasma wrapped by proteins like blood. Fish eyes were also visualized
in Fig. 22.22d. Figure 22.22e was developed by plotting PC1 scores expressing the
weakly hydrogen bonding water species [35]. The embryonic structure, contours of
oil droplets and the boundary of egg membranes were made clear. Especially, it was
541
exhibit protein distributions, they showed different variation patterns depending on
the protein secondary structures. The α-helix component in the egg yolk increased
with egg development (Fig. 22.21b), but the protein concentration with β-sheet structure, on the other hand, became higher on day 1 and JBH than during the intermediate
period (Fig. 22.21c). Monroy et al. investigated the pathway of yolk utilization during
egg development using a radioactive element for imaging [47]. They revealed that the
synthesis of embryonic proteins from the yolk and its utilization rate was different
depending on each developmental stage [47]. That is, the yolk has different roles at
each developmental stage, and NIR imaging might capture the metabolic changes
depending on the phases, in situ, without labeling. Figure 22.21d shows the distribution of unsaturated fatty acids constructed by the second derivative intensity at
4666 cm
−1 [41]. The highlighting of oil droplets and egg membrane in this image
indicates the existence of the unsaturated fatty acids in these embryonic structures.
22.6.3 High-Speed NIR Imaging of Fish Egg Embryogenesis
For high-speed NIR imaging, the Compovision system was used. Figure 22.22
depicts visible images of the fish eggs in the same day series (a), and NIR images
constructed using second derivative intensities and chemometrics (b)–(f) in the 1460–
1767 nm (6850–5660 cm
−1 ) region. In Fig. 22.22b made by the band at 1767 nm
(5660 cm
−1 ), which was assigned to the first overtone of C–H stretching mode of CH 2
groups in hydrocarbons and aliphatic compounds [40, 48, 49], clearly depicts the egg
membrane and oil droplets. Since cell membrane generally has a phospholipid bilayer
structure with many CH 2 groups, the structure is expected to be visualized. Furthermore, after third day, eye structures were also depicted using the band. The images
of the first overtone of C–H stretching band in CH 2 groups at 1716 nm (5828 cm
−1 )
are shown in Fig. 22.22c [40, 41, 49]. The band position of the first overtone of
C-H stretching in unsaturated fatty acids shifts from 1725 nm (5797 cm
−1 ) to 1709–
1717 nm (5851–5824 cm
−1 ) [41, 50]. Fish eggs contain much polyunsaturated fatty
acids such as docosahexaenoic acid and eicosapentaenoic acid. Therefore, Fig. 22.22c
can be interpreted to exhibit the distribution of unsaturated fatty acids. That is, the
distributions of different fatty acids depending on the degree of unsaturation can be
selectively visualized. The band intensity at 1564 nm (6394 cm
−1 ) due to the first
overtone of N–H stretching mode of amide groups was used to prepare Fig. 22.22d
[40, 45]. The membrane proteins were expected to make clear the egg membrane.
The heterogeneous highlight within oil droplets in Fig. 22.22d overlapped with the
part in Fig. 22.22b. This part may show the lipoprotein distribution in which lipids
present in plasma wrapped by proteins like blood. Fish eyes were also visualized
in Fig. 22.22d. Figure 22.22e was developed by plotting PC1 scores expressing the
weakly hydrogen bonding water species [35]. The embryonic structure, contours of
oil droplets and the boundary of egg membranes were made clear. Especially, it was