Types and Distribution of Bioactive Polyunsaturated Aldehydes in a Gradient from Mesotrophic to Oligotrophic Waters in the Alborán Sea (Western Mediterranean)

Abstract

Polyunsaturated aldehydes (PUAs) are bioactive molecules suggested as chemical defenses and infochemicals. In marine coastal habitats, diatoms reach high PUA production levels during bloom episodes. Two fractions of PUA can usually be analyzed: pPUA obtained via artificial breakage of collected phytoplankton cells and dissolved PUA already released to the environment (dPUA). In nature, resource supply arises as a main environmental controlling factor of PUA production. In this work, we monitored the vertical distribution and daily variation of pPUA associated with large-size phytoplankton and dPUA, at three sites located in the Alborán Sea from mesotrophic to oligotrophic waters. The results corroborate the presence of large-size PUA producers in oligotrophic and mesotrophic waters with a significant (58%–85%) diatom biomass. In addition to diatoms, significant correlations between pPUA production and dinoflagellate and silicoflagellate abundance were observed. 2E,4E/Z-Heptadienal was the most abundant aldehyde at the three sites with higher values (17.1 fg·cell−1) at the most oligotrophic site. 2E,4E/Z-Decadienal was the least abundant aldehyde, decreasing toward the oligotrophic site. For the first time, we describe the daily fluctuation of pPUA attributable to cellular physiological state and not exclusively to taxonomical composition. Our results demonstrate the persistence of threshold levels of dPUA deep in the water column, as well as the different chromatographic profiles of dPUA compared with pPUA. We propose different isomerization processes that alter the chemical structure of the released PUAs with unknown effects on their stability, biological function, and potential bioactivity.

Survey of the allelopathic potential of Mediterranean macroalgae: production of long-chain polyunsaturated aldehydes (PUAs)

“…both micro-and macroalgae). In addition, Bartual et al (2020) attested that µM ranges of dPUAs are expected to occur in the immediate vicinity of the producer cell, as occurred in this benthic environment, but disperse rapidly, consistently with pM to nM concentrations of dPUAs quantified in marine environments. A variety of aldehydes was putatively identified based on the mass spectra obtained at the three sampling times (Fig.…”

“…It is worth considering that most of the previous studies focused only on the detection of three PUAs, i.e. heptadienal (C7:2), octadienal (C8:2), and decadienal (C10:2) (Vidoudez et al, 2011;Morillo-García et al, 2014;Ribalet et al, 2014;Wu and Li, 2016;Bartual et al, 2018;Bartual et al, 2020). Together with octatrienal (C8:3), C7:2 and C8:2 resulted the most abundant dPUA in coastal areas of the Adriatic Sea (Vidoudez et al, 2011;Ribalet et al, 2014); C7:2, C8:2, and C10:2 were also the most abundant in the northern South China Sea (Wu and Li, 2016), as similarly reported by Bartual et al (2018) in southwestern Spain.…”

Changes of Volatile Flavor Compounds in Large Yellow Croaker (Larimichthys crocea) during Storage, as Evaluated by Headspace Gas Chromatography–Ion Mobility Spectrometry and Principal Component Analysis

“…For example, compared with the samples stored for 60, 90, and 120 d, a greater aldehyde content was present in the initial sample (see Table 1 ), which is consistent with the findings of Duan [ 42 ]. It should be noted here that aldehydes possess a low flavor threshold in addition to a characteristic fat aroma at low concentrations [ 43 ]. In the fresh fish meat (i.e., at day 0), the key volatile organic compounds present (area A, Figure 6 ) were methylpropanal (D), methylpropanal (M), hexanal (D), hexanal (M), ethanol, 2-hexenal (M), and 2-methylbutanal (D).…”

Multiple Roles of Diatom-Derived Oxylipins within Marine Environments and Their Potential Biotechnological Applications

“…A recent survey demonstrated that oxylipin pathways in diatoms were mostly based on the oxygenation of hexadecatrienoic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, and, within phytoplankton communities, these secondary metabolites largely derived from diatoms [ 42 ]. Moreover, daily fluctuations of PUAs were more correlated to the cellular physiological state of diatoms than exclusively to the taxonomical composition of phytoplankton communities [ 43 ].…”