Near-Infrared Spectroscopy and Imaging Studies of Fertilized Fish Eggs: In Vivo Monitoring of Egg Growth at the Molecular Level

Abstract

In this work, the growth of fertilized Japanese medaka (Oryzias latipes) eggs was monitored in vivo at the molecular level using near-infrared (NIR) spectroscopy and NIR imaging. NIR spectra were recorded noninvasively for three major parts of a fertilized medaka egg, the embryonic body, the oil droplets, and the yolk, from the first day after fertilization to the day before hatching. Principal component analysis (PCA) revealed that water, protein, and lipid contents in the egg yolk and oil droplets changed significantly just before hatching. The ratio of the characteristic peaks due to proteins and lipids in the second derivative spectra suggested that the relative concentration of proteins to lipids was constant in the egg yolk, while it dramatically increased just before hatching in the oil droplets. Furthermore, linear discriminant analysis (LDA) predicted the hatching possibility on the next day with 100% and 99.3% accuracy for yolk and oil droplets data, respectively. Two types of NIR images were developed in situ using the band intensities of the lipids and proteins in the second derivative spectra. The egg’s protein and lipid content was successfully visualized noninvasively. This technique should enable noninvasive quality testing of fertilized eggs in the future.

Lipid Droplet Composition Varies Based on Medaka Fish Eggs Development as Revealed by NIR-, MIR-, and Raman Imaging

“…Water interacts with the surrounding biomolecules such as proteins and lipids, and their compositional, concentration, and structural changes varies the interaction properties with water. In fact, the shape of the 5250 cm −1 water band in the second derivative spectrum was significantly different between the yolk and the oil droplets, indicating that the relative contribution of weakly and strongly hydrogen bonding water was different depending on contribution of surrounding water [13,28]. Furthermore, the data groups of the 1st, 5th, 9th days moved in minus direction PC2 overlapping each other.…”

“…In the previous work, published by Ishigaki et al, the water band in the second derivative NIR spectra obtained from the egg yolk drastically changed with the ones due to proteins and lipids on the day just before hatching. The big change enabled prediction of the hatching possibility with a very high accuracy, more than 99% [13].…”

“…[8][9][10][11][12]. Despite the fact that some reports described oil droplet size and their distribution in Oryzias latipes eggs, distinct changes in lipid components in developing eggs have not been identified yet [3,[13][14][15]. Oil droplet visualization can be performed with use of these label-free spectroscopic techniques employing imaging mode.…”

“…1 mm, near-infrared (NIR) imaging is the method of choice because of the possibility of examining thick samples such an eggs without special sample preparation. Based on NIR data, in previous study it was suggested that just before hatching, energy metabolism in Oryzias latipes eggs is changed [13]. Although NIR imaging enables measurement of a whole egg in a water environment and to determine biochemical components distribution, it is often difficult to interpret NIR spectra and to study subtle changes in chemical composition on contrary to mid-infrared (MIR) and Raman spectra that provide a fingerprint of molecules giving detailed information about the composition and molecular structure of a sample.…”

Near‐Infrared Imaging of Polymers; from Basic Science to Industrial Applications

“…NIR imaging has been extensively applied to studies in biomedical, pharmaceutical, foods, and polymer fields. (7,11,(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) Among biomedical applications, functional near-infrared (fNIR) or functional near-infrared spectroscopy (fNIRS) is very unique and has been used for functional neuroimaging. (27) Using fNIR, brain activity can be monitored through hemodynamic responses associated with neuron behavior.…”