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Fourier transform infrared microspectroscopy (FTIR) is a promising method for the analysis of biological samples. Recent studies reported that FTIR imaging allows determination of the distribution of several biomolecules in a sample with no staining or extraction. In this study, FTIR was used to monitor biochemical changes in C. elegans nematodes cultured in nematode maintenance media (CeMM) without supplementation and with supplementation with either a long chain polyunsatured omega 3 fatty acid, eicosapentaenoic acid (EPA) or a saturated fatty acid, palmitic acid (PA) at 100 μM. EPA is an omega 3 fatty acid with documented health benefits while PA is generally consumed in diets. Worms were placed on BaF2 slides, and FTIR spectra were collected from single worms in transmission mode using a focal plane array detector. Principal component analysis grouped the FTIR spectra into three clusters corresponding to spectra of worms cultured with no supplementation, worms cultured with supplementation with EPA, and worms cultured with supplementation with PA. The major differences between the FTIR spectra reside in the vibrations corresponding to unsaturated fatty acids (3008 cm−1), lipids (2928, 2848, and 1744 cm−1), and proteins (1680, 1648, and 1515 cm−1). This indicates that supplementation with EPA or PA leads to biochemical alterations related to unsaturated fatty acids, lipids, and proteins. Furthermore, supplementing mutant strains (tub-1 and fat-3) CeMM with PA resulted in the appearance of the vibration 3008 cm−1, an increase in the intensity of the vibration 1744 cm−1, and a new vibration at 1632 cm−1, which is assigned to the amide I of β-pleated sheet component of proteins, in the spectra of tub-1 and fat-3 mutant strains. The results illustrated the potential use of FTIR alongside other techniques such as gas chromatography and staining techniques to investigate lipid metabolism and fat accumulation as well as induced changes in protein structures.

This study reports on the use of Fourier transform infrared (FTIR) microspectroscopy imaging to investigate biochemical changes occurring during C. elegans lifespan. C. elegans wild-type (N2) and the tub-1 mutant strain were cultured in agar plates. FTIR imaging was performed on single worms in transmission mode at day 8, 11, and 15. Principal component analysis was then performed to analyze the spectra acquired during C. elegans lifespan. The FTIR spectra were clustered in three groups corresponding to the spectra acquired from the worms at day 8, 11, and 15. The results showed major changes in lipids (vibration 1744 cm−1 assigned to C O stretching) and proteins (vibrations 1648 cm−1 assigned to C O stretching of amide I and 1548 cm−1 assigned to N H bending and C–N stretching in amid II). The vibration assigned to glycogen around 1155 cm−1 was present in the spectra acquired at day 8 and 11 but the peak area decreased by 49.3% and 73.3% in the spectra acquired at day 15 respectively from WT(N2) and tub-1 mutant strain. Furthermore, PC-1 loadings as a function of wavenumbers show that the presence of the vibration 1698 cm−1, attributed to antiparallel β-sheet, could indicate the formation of lipofuscin. The results obtained demonstrate that FTIR imaging could be used as a tool to monitor biochemical changes during lifespan studies, which could bring additional information to our understanding of longevity.

Obesity is a complex disease that is influenced by several factors, such as diet, physical activity, developmental stage, age, genes, and their interactions with the environment. Obesity develops as a result of expansion of fat mass when the intake of energy, stored as triglycerides, exceeds its expenditure. Approximately 40% of the US population suffers from obesity, which represents a worldwide public health problem associated with chronic low-grade adipose tissue and systemic inflammation (sterile inflammation), in part due to adipose tissue expansion. In patients with obesity, energy homeostasis is further impaired by inflammation, oxidative stress, dyslipidemia, and metabolic syndrome. These pathologic conditions increase the risk of developing other chronic diseases including diabetes, hypertension, coronary artery disease, and certain forms of cancer. It is well documented that several bioactive compounds such as omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are able to reduce adipose and systemic inflammation and blood triglycerides and, in some cases, improve glucose intolerance and insulin resistance in vertebrate animal models of obesity. A promising model organism that is gaining tremendous interest for studies of lipid and energy metabolism is the nematode Caenorhabditis elegans. This roundworm stores fats as droplets within its hypodermal and intestinal cells. The nematode's transparent skin enables fat droplet visualization and quantification with the use of dyes that have affinity to lipids. This article provides a review of major research over the past several years on the use of C. elegans to study the effects of ω-3 PUFAs on lipid metabolism and energy homeostasis relative to metabolic diseases.

Caenorhabditis elegans nematode has emerged as a model organism paving the ways for multidisciplinary research in biomedical, environmental toxicology, aging, metabolism, obesity, and drug discovery. The wide range of applications of this model organism are attributed to C. elegans’ unique features: C. elegans are inexpensive, easy to grow and maintain in a laboratory, has a short lifespan, and has a small body size. With this increased interest, the need for analytical techniques to assess the biochemical information on intact worms continues to grow. Fourier Transform Infrared (FTIR) microspectroscopy is considered as a powerful technique that can be used to determine the chemical structure and composition of various materials, including biological samples. Furthermore, the development of focal plane array detectors has made this technique attractive to study complex biological systems such as whole nematodes. This review focuses on the use of FTIR microspectroscopy to study C. elegans. The first published work on the use of FTIR microspectroscopy to study a complex whole animal was reported in 2004. Since then, very few other studies were carried out. The objective of this review is to summarize work conducted to date using FTIR microspectroscopy to study nematodes and to discuss the information that can be gained by using this technique. This could allow scientists to add this technique to the arsenal of techniques already in use for C. elegans studies.

This study focuses on the use of Fourier Transform Infrared (FTIR) microspectroscopy to determine chemical changes induced in the nematode Caenorhabditis elegans by supplementation of C. elegans maintenance media (CeMM) by Eicosapentaenoic acid (EPA). Wild-type C. elegans (N2) and mutant strains (tub-1 and fat-3) were grown in CeMM alone, and CeMM supplemented with EPA at 25 or 100 μM. Feeding was performed for 72 h. FTIR imaging was performed in transmission mode on individual worms. The FTIR imaging analysis of wild-type animals revealed the presence of vibrations assigned to unsaturated fatty acids, specifically bands at 3008 cm-1 ([double bond, length as m-dash]C-H, olefinic stretch) and 1744 cm-1 (C[double bond, length as m-dash]O, unsaturated fatty acids). It confirmed previously reported synthesis of unsaturated fatty acids in wild-type C. elegans. For the FTIR spectra of mutant strains, these vibrations were absent or present only as very small shoulder, which indicates that tub-1 and fat-3 synthesize essentially saturated fatty acids as indicated by the presence of -CH2 and C[double bond, length as m-dash]O vibrations. These results are in agreement with previous studies which reported that these mutants have altered lipid compositions. Principal component analysis showed differences in chemical composition between wild-type and mutant strains as well as between mutant strains cultured in normal CeMM and those cultured in CeMM supplemented with EPA. This study demonstrated the usefulness of FTIR microspectroscopy to investigate fat metabolism in C. elegans.