Baleen Whale Protein Analysis with LC-ESI-MS

A recent study assessed the ease of applying shotgun proteomics to blubber biopsy samples collected from free-ranging baleen whales as well as proteins extracted from that blubber. Those proteins were separated and identified using nanoflow liquid chromatography electrospray ionization in tandem with mass spectrometry (LC–ESI– MS).

According to the study (1), which was published in Conservation Physiology, the value of creating a suite of such protein biomarkers is that there is the potential of better assessing the overall health and physiological state of live whales through remote biopsy sampling. This information is vital for population health assessments to predict population trajectories and can ultimately guide and monitor conservation priorities and initiatives. As over 25% of cetacean species worldwide are listed as critically endangered, endangered, or vulnerable by the International Union for Conservation of Nature, the need for objective and widely applicable tools to assess cetacean health are vital for monitoring whale population monitoring and creating useful conservation initiatives.

Samples were collected from minke whales (Balaenoptera acutorostrata) in the Gulf of St. Lawrence, Canada. These samples were taken over a 4-month period (June to September, inclusive) in 2013 during the summer feeding season where minke whalesare expected to fatten considerably (2). Researchers were able to identify 434 unique proteins in the blubber tissue, with over half of them involved in cellular metabolism. This is keeping with previous research conducted on elephant seal blubber, which revealed that metabolism was the most significantly enriched biological process (3,4). Almost half (48.8%) of the proteins identified were only detected once, and just <20% were detected more than five times across these extracts. The six most frequently identified proteins were hemoglobin, fatty acid-binding protein, apolipoproteins, immunoglobulins, serum albumin, and perilipins.

Total protein was extracted using a radioimmunoprecipitation assay (RIPA) cell lysis and extraction buffer-based protocol. The researchers mapped proteins to known biological pathways and determined whether they were significantly enriched based on the proteome profile. A pathway enrichment map was created to visualize overlap in tissue-level biological processes.

Amongst the most significantly enriched biological pathways were those involved in immune system function: inflammatory responses, leukocyte-mediated immunity, and the humoral immune response. Pathways associated with responses to oxidative stress were also enriched.

The researchers state that, moving forward, the targeted quantification of different hormones and proteins involved in various specific metabolic pathways within blubber tissue may lead tofurther development of potential new protein markers of immune system function, oxidative stress. and lipid metabolism of interest. It is their belief that the next step in cetacean proteomics research is the explanation and quantification of the natural variability in both targeted and non-targeted approaches in the context of different life history strategies or periods of the life cycle, and specifically its application to population health assessments of baleen whales.

Minke whale. © Cristian- stock.adobe.com

References

1. Kershaw, J.; Ramp, C.; Sears, R.; Hall, A.; Derous, D. Proteome Profiling Reveals Opportunities to Investigate Biomarkers of Oxidative Stress and Immune Responses in Blubber Biopsies from Free-Ranging Baleen Whales, Conserv. Physiol. 2024, 12 (1), coae059,.DOI: 10.1093/conphys/coae059

2. Christiansen, F.; Víkingsson, G. A.; Rasmussen, M. H.; Lusseau, D. Minke Whales Maximise Energy Storage on their Feeding Grounds. J. Exp. Biol. 2013, 216 (3), 427-436. DOI: 10.1242/jeb.074518

3. Khudyakov, J. I.; Champagne, C. D.; Meneghetti, L. M.; Crocker, D. E. Blubber Ttranscriptome Response to Acute Stress Axis Activation Involves Transient Changes in Adipogenesis and Lipolysis in a Fasting-Adapted Marine Mammal. Sci. Rep.s 2017, 7 (1), 42110. DOI: 10.1038/srep42110

4. Deyarmin, J.; Hekman, R.; Champagne, C.; McCormley, M.; Stephan, A.; Crocker, D. et al.Blubber Proteome Response to Repeated ACTH Administration in a Wild Marine Mammal. Comp. Biochem. Physiol., Part D: Genomics Proteomics 2020, 33, 100644. DOI: 10.1016/j.cbd.2019.100644