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- Intermittent hypoxia training remodels the hepatic mitochondrial network and upregulates ANT expression to enhance hypoxia tolerance in Micropterus salmoidesPublication . Liu, Hao; Zhang, Dongmei; Hu, Yifan; Yan, Haoxiao; Luo, Weizhe; He, Kuo; Zhang, Zhenghui; Yang, Hangyu; Power, Deborah Mary; Canario, Adelino; Liu, Qiao; Yang, Song; Zhao, LiulanOxygen is critical for life, and aquatic organisms are especially susceptible to hypoxic stress caused by environmental fluctuations. However, the mechanisms underpinning their tolerance to hypoxia remain poorly understood. Largemouth bass (Micropterus salmoides) is widely distributed across a range of freshwater ecosystems and has significant economic and ecological value. Low oxygen has become a key limiting factor in the aquaculture of this species. This study examined the impact of intermittent hypoxia training (IHT) on hypoxia tolerance of largemouth bass by simulating the daily fluctuations in dissolved oxygen typical of natural aquatic environments. We found that IHT increased the hypoxic tolerance of largemouth bass by activating adenine nucleotide translocase (ANT) which mediated Ca2+ influx and cellular resistance to hypoxia. Inhibition of ANT compromised hypoxia tolerance by reducing hypoxia-induced mitochondrial Ca2+ accumulation and mitochondrial quality control. Additionally, ANT inhibition upregulated the expression of genes associated with oxidative stress and apoptosis. These findings highlight a key relationship between ANT and mitochondrial Ca2+ signaling in response to hypoxia, providing insights into the mechanism that enhances tolerance to hypoxia in largemouth bass.
- Use of aquatic organisms as flagship species in selecting priority areas for conservationPublication . Guerrero-Moreno, Mayerly Alexandra; Silva, Everton Cruz da; Oliveira, Fernando Abreu; Nascimento, Ana Caroline Leal; Michelan, Thaisa Sala; Dias-Silva, Karina; Teodosio, Maria; Jr, James Ferreira Moura; Oliveira-Junior, José Max Barbosa; Juen, LeandroFlagship species are widely used to garner support for conservation, but the selection of these taxa often overlooks ecological, social, and cultural criteria, which may limit the effectiveness of conservation efforts in priority areas. Furthermore, this approach often fails to adequately reflect the importance of ecosystems. A notable example is the undervaluation of aquatic environments, which are frequently neglected or assessed using terrestrial groups whose characteristics and requirements do not necessarily align with the specific demands of these ecosystems. In light of this, we conducted a scientometric analysis to map the scientific literature on the use of aquatic organisms as flagship species for selecting priority conservation areas, highlighting global trends and gaps. A total of 400 articles published between 1997 and 2024 were analyzed from the Scopus and Web of Science databases. The highest number of articles published was in 2021 (n = 46; 11.5 %). Australia (n = 49) and Brazil (n = 34) were the countries most frequently studied. The most frequently researched areas were marine/ coastal protected areas (43.75 %) and unprotected natural areas (42.50 %). More than 80 % of the flagship species belonged to the phylum Chordata, with notable representation from Actinopterygii (bony fishes; 43.58 %) and Mammalia (20.18 %). The most commonly used taxon selection criteria were “conservation status” (57.17 %) and “charisma and emblematic value” (15.80 %). Despite the representation of marine ecosystems (58.63 %), freshwater habitats such as rivers (16.78 %), lakes (4.96 %), and streams (4.26 %) remain underrepresented. The most frequently employed research methods and response metrics were “abundance and density” (39.04 %) and “monitoring and observation” (38.32 %). We identified a significant bias favoring marine ecosystems and charismatic taxa, neglecting freshwater habitats and less visible but ecologically important groups. We emphasize the need to diversify conservation strategies by adopting more inclusive approaches that encompass the full range of aquatic biodiversity and habitats, particularly those that are underrepresented. Such diversification is essential for strengthening public policies and practices aimed at protecting critical ecosystems and ensuring global environmental sustainability.
- Microalgae protein: a comparison between spray-dryed and frozen paste cellsPublication . Moreira, Catarina; Nunes, Rafaela; Kholany, Mariam; Pereira, Hugo; Teixeira, José A.; Ferreira-Santos, Pedro; Rocha, Cristina M.R.The need for sustainable protein substitutes is being driven by the growing global population. Because of their high protein content and environmental sustainability, microalgae are a viable source. In this study, proteins extracted from frozen paste and spray-dried biomass from Nannochloropsis oceanica and Tetraselmis chui were studied. High-pressure homogenization, followed by ultrafiltration (non-purified, NPS) and ammonium sulfate precipitation (purified, PS), was used to process the protein extracts. PS extracts showed higher protein concentrations, reaching approximately three-fold higher levels than NPS in spray-dried N. oceanica and about 2.7-fold higher in frozen paste samples, while frozen paste T. chui exhibited a 2.6-fold increase. Spectroscopic and chromatographic analyses revealed that frozen paste extracts preserved a greater proportion of native protein structures and displayed higher hydrophobic site exposure, whereas spraydrying and purification reduced α-helix content and promoted protein aggregation. Despite their lower protein concentration, frozen paste NPS extracts exhibited more favorable structural characteristics that may support improved techno-functional performance. These results highlight the importance of selecting processing conditions based on intended applications. Future food formulations could benefit greatly from the use of microalgal proteins, especially those derived from frozen biomass, as adaptable and sustainable ingredients.
- Synthesis, characterization, hirshfeld surface analysis of V-substituted keggin polyoxotungstates and Ca2+-ATPase inhibiting potentialPublication . Meskini, Islem; Fraqueza, Gil; Capet, Frédéric; Aureliano, Manuel; Ayed, BrahimPolyoxometalates (POMs) biological and biomedical applications have attracted increasing attention over the past decades. Polyoxometalates are inorganic transition metal oxygen clusters characterized by having multiple structures and tunable electronic properties that are well-known to be effective inhibitors of many enzymes, such as ATPases. Herein, a new hybrid POM of the Keggin type, Vanadium-substituted Keggin polyoxotungstate, namely (C₆H₁₅N)₄(C₆H₁₆N)₆(VW₁₂O₄₀)₂⋅4H₂O, was synthesized via wet-chemical methods in aqueous solution. Its purity was confirmed, and the compound was fully characterized by single-crystal X-ray diffraction, infrared spectroscopy, UV–visible spectroscopy, and thermogravimetric analysis. The Keggin-type compound exhibited a half maximal inhibitory concentration (IC50) value of 8.25 μM toward calcium adenosine triphosphatase (Ca2+- ATPase) inhibition, as measured spectrophotometrically using a coupled pyruvate kinase/lactate dehydrogenase enzyme assay. Hirshfeld surface analysis was employed to investigate intermolecular interactions within the crystal structure, revealing differences in hydrogen bonding and oxygen-based contacts. These structural features may suggest a possible relationship with the observed biological activity; however, no direct correlation with Ca2+-ATPase inhibition can be firmly established from the present data. Therefore, the observed relationships should be considered preliminary and structural in nature, rather than mechanistic. Further computational and biological studies are required to clarify the role of these interactions in enzyme inhibition.
- Size-dependent salinity tolerance in juvenile stellate sturgeon (Acipenser stellatus): physiological and histopathological responsesPublication . Pajand, Zabih Ollah; Hosseinnia, Esmaeil; Jafari Pastaki, Naghmeh; Hallajian, Ali; Yousefi, Ayoub; Lebria, Arash; Ashori, Alireza; Abdollahpour, HamedWe investigated the physiological, endocrine, and histological responses of juvenile stellate sturgeon (Acipenser stellatus) to salinity challenge across four weight classes (0.89 ± 0.21, 2.01 ± 0.32, 4.84 ± 0.39, and 9.07 ± 1.47 g; mean ± S.E.) and four salinity levels (0, 4, 8, and 12 ppt) over acute to chronic exposure (3–624 h). A total of 4800 juveniles were used across four sequential experiments, with 100 ± 5 fish per tank (12 tanks per experiment). A replicated factorial design (three tanks per treatment) enabled robust assessment of ionoregulation, stress response, and tissue integrity. Plasma osmolality increased from approximately 230 to 266 mOsm kg− 1 during early exposure, followed by progressive convergence toward a narrower physiological range (≈251–284 mOsm kg− 1 ) at 624 h, indicating partial osmotic compensation. This adjustment was driven primarily by sodium, which exhibited the strongest salinity- and size-dependent response, confirming its central role in extracellular osmotic regulation. In contrast, potassium displayed pronounced size-dependent dysregulation, with markedly elevated concentrations in fish 3 g maintained values within or near the physiological range. Cortisol dynamics revealed a clear ontogenetic shift in stress responsiveness. Smaller juveniles (3 g) demonstrated more efficient recovery, with the 5–10 g group achieving ~92% recovery by 96 h, compared to only ~45% in the smallest size class. These endocrine patterns were consistent with ionoregulatory performance and further support a size-dependent transition in physiological resilience. Histopathological analysis corroborated systemic findings. Histopathological analysis using a semi-quantitative scoring system (0–4) revealed significant size- and salinity-dependent tissue alterations. Gill tissues showed lamellar fusion, epithelial lifting, hyperplasia, necrosis, and hemorrhage, with more severe lesions in smaller juveniles at intermediate to high salinities. Kidney tissues exhibited glomerular expansion, tubular degeneration and obstruction, congestion, hemorrhage, and hemosiderin deposition, with lesion severity generally decreasing with increasing body size. These histological patterns were consistent with physiological and endocrine responses and reflected greater structural resilience in larger juveniles under salinity stress. Collectively, these integrated responses identify an empirical transition zone at approximately 3 g under the tested conditions, below which juveniles exhibit limited capacity to maintain physiological homeostasis under salinity challenge. Above this threshold, fish display more effective physiological regulation, resulting in better ion balance, lower stress, and improved tissue integrity. Together, these findings provide mechanistic evidence for size-based acclimation protocols, gradual salinity transitions, and optimized release strategies to enhance survival and performance in aquaculture and stock enhancement programs.