Specific polyunsaturated fatty acids modulate lipid delivery and oocyte development in C. elegans revealed by molecular-selective label-free imaging

• Published in: Scientific reports Vol. 6; no. 1; p. 32021
• Main Authors: Chen, Wei-Wen, Yi, Yung-Hsiang, Chien, Cheng-Hao, Hsiung, Kuei-Ching, Ma, Tian-Hsiang, Lin, Yi-Chun, Lo, Szecheng J., Chang, Ta-Chau
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18-08-2016; Nature Publishing Group
• Subjects: 14/63; 140/133; 38/35; 631/136/2434/1706; 631/1647/767/722; 639/624/1111/55; 639/638/11/942; 639/638/440/527/1821; 64/11; Animals; Caenorhabditis elegans - growth & development; Caenorhabditis elegans - metabolism; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Fatty Acid Desaturases - deficiency; Fatty Acid Desaturases - genetics; Fatty Acid Desaturases - metabolism; Fatty acids; Fatty Acids, Omega-6 - metabolism; Fatty Acids, Unsaturated - chemistry; Fatty Acids, Unsaturated - metabolism; Humanities and Social Sciences; Image processing; Lipids; Lipids - analysis; Lipids - chemistry; Lipoproteins; Lipoproteins - chemistry; Lipoproteins - metabolism; Microscopy; multidisciplinary; Mutagenesis; Nematodes; Oocytes; Oocytes - growth & development; Oocytes - metabolism; Optical Imaging; Polyunsaturated fatty acids; Science; Spectrum Analysis, Raman; Yolk; Yolk Sac - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep32021

Polyunsaturated fatty acids (PUFAs) exhibit critical functions in biological systems and their importance during animal oocyte maturation has been increasingly recognized. However, the detailed mechanism of lipid transportation for oocyte development remains largely unknown. In this study, the transportation of yolk lipoprotein (lipid carrier) and the rate of lipid delivery into oocytes in live
C. elegans
were examined for the first time by using coherent anti-Stokes Raman scattering (CARS) microscopy. The accumulation of secreted yolk lipoprotein in the pseudocoelom of live
C. elegans
can be detected by CARS microscopy at both protein (~1665 cm
−1
) and lipid (~2845 cm
−1
) Raman bands. In addition, an image analysis protocol was established to quantitatively measure the levels of secreted yolk lipoprotein aberrantly accumulated in PUFA-deficient
fat
mutants (
fat-1
,
fat-2
,
fat-3
,
fat-4
) and PUFA-supplemented
fat-2
worms (the PUFA add-back experiments). Our results revealed that the omega-6 PUFAs, not omega-3 PUFAs, play a critical role in modulating lipid/yolk level in the oocytes and regulating reproductive efficiency of
C. elegans
. This work demonstrates the value of using CARS microscopy as a molecular-selective label-free imaging technique for the study of PUFA regulation and oocyte development in
C. elegans
.