Macromolecular Characterization of Swordfish Oocytes by FTIR Imaging Spectroscopy

Abstract

During folliculogenesis, primary oocytes of teleosts grow by several orders of magnitude by-self synthesizing proteins and mRNA, or sequestering from blood specific macromolecular components, such as fatty acids and vitellogenin. All these materials are stored into cortical alveoli, yolk globules or oil droplets during oocyte development. The proper synthesis, storage and displacement of these macromolecular components inside the oocyte play a key role for a successful fertilization process and for the subsequently correct embryo development. In this study, for the first time, the FTIR Imaging (FTIRI) spectroscopy has been applied to characterize the chemical building blocks of several cellular components of swordfish oocytes at different developmental stages. In particular, the spectral features of previtellogenic (PV), vitellogenic (VTG), mature (M) and atretic (A) follicles as well as and of cortical alveoli (CA), yolk vesicles (YV), oil droplets (OD) and Zona Radiata (ZR) have been outlined, providing new insights in terms of composition and topographical distribution of macromolecules of biological interest such as lipids, proteins, carbohydrates and phosphates. The macromolecular characterization of swordfish oocytes at different developmental stages represents a starting point and a useful tool for the assessment of swordfish egg quality caught in different conditions, such as periods of the year or different fishing area.

Maturity assignment based on histology‐validated macroscopic criteria: Tackling the stock decline of the Mediterranean swordfish (Xiphias gladius)

“…Sections of 5 μm in width were cut with a microtome (model RM2125 RTS; Leica Biosystems, Wetzlar, Germany), stained with Mayer's haematoxylin/eosin, and examined under a microscope (Axio Imager 2; Zeiss, Oberkochen, Germany). An assessment of the reproductive status of samples was performed according to the modified scale of Brown‐Peterson et al (), and with reference to previous works on Mediterranean swordfish reproduction (Carnevali et al, ; Corriero et al, ; Macías et al, ; Ortiz‐Delgado, Porcelloni, Fossi, & Sarasquete, ). The individuals caught during the reproductive season were assigned to five stages: (i) immature, (ii) developing (vitellogenic), (iii) spawning, (iv) post‐spawning, and (v) regenerating (spent).…”

Knockout of the Glucocorticoid Receptor Impairs Reproduction in Female Zebrafish

“…With Fourier transform infrared imaging (FTIRI) spectroscopy, the infrared imaging analysis of small areas of biological samples, such as tissues and cells, was performed. IR maps, in which each pixel corresponds to an IR spectrum and represents the total infrared absorbance in the MIR spectral range (4000-800 cm −1 ) area [19,20], were generated. The integration of IR maps in different spectral ranges, specific for different biocomponents (such as lipids, proteins, and so on), generates false color images showing the topographical distribution of the investigated macromolecules on the mapped area.…”

“…For each section, three oocytes of classes III and IV were selected; it was not possible to distinguish between IIIa and IIIb since the analysis was performed on ovarian sections, instead of single mechanically isolated oocytes [19].…”

Fourier transform near infrared spectroscopy as a tool to predict spawning status in Alaskan fishes with variable reproductive strategies

“…5,6 Recent applications include otoliths and other hard structures from fishes for age determination 5,[7][8][9][10][11][12] and tissues for quantifying fish condition. 13 A variety of vibrational spectroscopy techniques, including FT-NIR spectroscopy, have already been applied to ovarian tissue to correlate plasma spectra with developing oocyte features to determine the quality of farmed caviar; 14 monitor the growth of fertilized eggs; 15 characterize oocyte development stages; 16 and for the classification or characterization of follicular atresia. 16,17 Although FT-NIR spectroscopy is a tool that has the capability to measure quantitative and qualitative information from various biological tissues collected from fishes, it has yet to be applied to determine spawning status from ovarian tissue.…”