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Recent Submissions

  • Submarine optical fiber communication provides an unrealized deep-sea observation network

    Guo, Yujian; Marin, Juan M.; Ashry, Islam; Trichili, Abderrahmen; Havlik, Michelle-Nicole; Ng, Tien Khee; Duarte, Carlos M.; Ooi, Boon S. (Scientific Reports, Springer Science and Business Media LLC, 2023-09-18) [Article]
    Oceans are crucial to human survival, providing natural resources and most of the global oxygen supply, and are responsible for a large portion of worldwide economic development. Although it is widely considered a silent world, the sea is filled with natural sounds generated by marine life and geological processes. Man-made underwater sounds, such as active sonars, maritime traffic, and offshore oil and mineral exploration, have significantly affected underwater soundscapes and species. In this work, we report on a joint optical fiber-based communication and sensing technology aiming to reduce noise pollution in the sea while providing connectivity simultaneously with a variety of underwater applications. The designed multifunctional fiber-based system enables two-way data transfer, monitoring marine life and ship movement near the deployed fiber at the sea bottom and sensing temperature. The deployed fiber is equally harnessed to transfer energy that the internet of underwater things (IoUTs) devices can harvest. The reported approach significantly reduces the costs and effects of monitoring marine ecosystems while ensuring data transfer and ocean monitoring applications and providing continuous power for submerged IoUT devices.
  • Dipeptide-Based Photoreactive Instant Glue for Environmental and Biomedical Applications

    Bilalis, Panagiotis; Alrashoudi, Abdulelah Α.; Susapto, Hepi Hari; Moretti, Manola; Alshehri, Salwa; Abdelrahman, Sherin; Elsakran, Amr; Hauser, Charlotte (Accepted by ACS Applied Materials and Interfaces, 2023-09-13) [Article]
    Nature-inspired smart materials offer numerous advantages over environment-friendliness and efficiency. Emulating the excellent adhesive properties of mussels foot proteins, where the Lysine is in close proximity with the 3,4-dihydroxy-L-phenylalanine (DOPA), we report the synthesis of a novel photo-curable peptide-based adhesive consisting exclusively of these two amino acids. Our adhesive is a highly concentrated aqueous solution of a monomer, a crosslinker and a photoinitiator. Lap-shear adhesion measurements on plastic and glass surfaces and comparison with different types of commercial adhesives showed that the adhesive strength of our glue is comparable when applied in the air and superior when used underwater. No toxicity of our adhesive was observed when the cytocompatibility on human dermal fibroblast cells was assessed. Preliminary experiments with various tissues and coral fragments showed that our adhesive could be applied to wound healing and coral reef restoration. Given the convenience of the facile synthesis, biocompatibility, ease of application underwater and high adhesive strength, we expect that our adhesive may find application, but not limited, to the biomedical and environmental field.
  • Quantification and distribution of marine microdebris in the surface waters of Livingston Island (South Shetland Islands, Antarctica).

    Monràs-Riera, Pere; Angulo-Preckler, Carlos; Avila, Conxita (Marine pollution bulletin, Elsevier BV, 2023-09-08) [Article]
    Microdebris are ubiquitous and the Southern Ocean is no exception. Despite the recent increment in Antarctic studies assessing this threat, there is still scarce information available. Here, we quantified the microdebris in surface water, and their distribution within two bays of Livingston Island (South Shetlands, Antarctica). The two studied bays included one with human presence and one pristine, barely visited. Microdebris pollution was found in all samples with a mean concentration of 0.264 ± 0.185 items/m3. Fibres (82.19 %) were the main item, with polyester (61.67 %) as the main plastic polymer, followed by nylon (29.54 %). No differences in the distribution pattern were observed, with microdebris being homogeneously distributed along the two bays. Our results suggest that nearshore waters of Livingston Island are prone to the accumulation and retention of microdebris. The composition of the microdebris also points to Antarctic local activities as principal contamination contributors.
  • Topsoil selenium (Se) under Se-rich farming in China: Current status, cropping impacts and ecological risk assessment.

    Qian, Li; Wang, Ting; Shi, Yajuan; Xu, Qiuyun; Zhou, Xuan; Ke, Lingjie; Liang, Ruoyu; Fu, Chuancheng; Zheng, Xiaoqi; Sun, Guoxin (Journal of environmental management, Elsevier BV, 2023-09-04) [Article]
    Selenium (Se), as an essential microelement, can be supplied through Se-biofortified food from Se-rich soils and associated farming practices for human health, while it can also cause eco-risks if overapplied. In this study, a multi-scale spatiotemporal meta-analysis was conducted to guide sustainable Se-rich farming in China by combining a long-term survey with a reviewed database. The weighted mean concentration, spatial distribution of soil Se, nationwide topsoil Se variation from cropping impacts and its bioavailability-based ecological risks were assessed and quantified. The results showed that the weighted mean content (0.3 mg kg−1) of China was slightly higher than that of previous nationwide topsoil Se surveys, as more Se-rich areas were found in recent high-density sampling surveys. Cropping has overall reduced Se content by 9.5% from farmland across China and deprived more with the increase in farming rotation driven by geo-climatic conditions. Long-term cropping removed Se from Se-rich areas but accumulated it in Se-deficient areas. Additionally, the bioavailable Se content of topsoil in China ranged from 0 to 332 μg kg−1, and the bioavailability-based eco-risks indicated that high eco-risks only existed in overfertilized and extremely high-Se soils, such as in Enshi, Ziyang and some coalfield areas. This work provides evidence for the development of sustainable Se-rich farming with proper utilization of soil Se resources, simultaneously protecting the soil eco-environment.
  • Sustainable reference points for multispecies coral reef fisheries.

    Zamborain-Mason, Jessica; Cinner, Joshua E.; MacNeil, M Aaron; Graham, Nicholas A. J.; Hoey, Andrew S.; Beger, Maria; Brooks, Andrew J; Booth, David J; Edgar, Graham J; Feary, David A; Ferse, Sebastian C A; Friedlander, Alan M; Gough, Charlotte L A; Green, Alison Lesley; Mouillot, David; Polunin, Nicholas V C; Stuart-Smith, Rick D; Wantiez, Laurent; Williams, Ivor D; Wilson, Shaun K.; Connolly, Sean (Nature communications, Springer Science and Business Media LLC, 2023-09-04) [Article]
    Sustainably managing fisheries requires regular and reliable evaluation of stock status. However, most multispecies reef fisheries around the globe tend to lack research and monitoring capacity, preventing the estimation of sustainable reference points against which stocks can be assessed. Here, combining fish biomass data for >2000 coral reefs, we estimate site-specific sustainable reference points for coral reef fisheries and use these and available catch estimates to assess the status of global coral reef fish stocks. We reveal that >50% of sites and jurisdictions with available information have stocks of conservation concern, having failed at least one fisheries sustainability benchmark. We quantify the trade-offs between biodiversity, fish length, and ecosystem functions relative to key benchmarks and highlight the ecological benefits of increasing sustainability. Our approach yields multispecies sustainable reference points for coral reef fisheries using environmental conditions, a promising means for enhancing the sustainability of the world's coral reef fisheries.
  • Top abundant deep ocean heterotrophic bacteria can be retrieved by cultivation

    Sanz-Saez, Isabel; Sanchez, Pablo; Salazar, Guillem; Sunagawa, Shinichi; de Vargas, Colomban; Bowler, Chris; Sullivan, Matthew B.; Wincker, Patrick; Karsenti, Eric; Pedrós-Alió, Carlos; Agusti, Susana; Gojobori, Takashi; Duarte, Carlos M.; Gasol, Josep M.; Sánchez, Olga; Acinas, Silvia G (ISME Communications, Springer Science and Business Media LLC, 2023-09-02) [Article]
    Traditional culture techniques usually retrieve a small fraction of the marine microbial diversity, which mainly belong to the so-called rare biosphere. However, this paradigm has not been fully tested at a broad scale, especially in the deep ocean. Here, we examined the fraction of heterotrophic bacterial communities in photic and deep ocean layers that could be recovered by culture-dependent techniques at a large scale. We compared 16S rRNA gene sequences from a collection of 2003 cultured heterotrophic marine bacteria with global 16S rRNA metabarcoding datasets (16S TAGs) covering surface, mesopelagic and bathypelagic ocean samples that included 16 of the 23 samples used for isolation. These global datasets represent 60 322 unique 16S amplicon sequence variants (ASVs). Our results reveal a significantly higher proportion of isolates identical to ASVs in deeper ocean layers reaching up to 28% of the 16S TAGs of the bathypelagic microbial communities, which included the isolation of 3 of the top 10 most abundant 16S ASVs in the global bathypelagic ocean, related to the genera Sulfitobacter, Halomonas and Erythrobacter. These isolates contributed differently to the prokaryotic communities across different plankton size fractions, recruiting between 38% in the free-living fraction (0.2–0.8 µm) and up to 45% in the largest particles (20–200 µm) in the bathypelagic ocean. Our findings support the hypothesis that sinking particles in the bathypelagic act as resource-rich habitats, suitable for the growth of heterotrophic bacteria with a copiotroph lifestyle that can be cultured, and that these cultivable bacteria can also thrive as free-living bacteria.
  • Physiology of the widespread pulsating soft coral Xenia umbellata is affected by food sources, but not by water flow

    Hill, C. E. L.; Abbass, S. G.; Caporale, G.; El-Khaled, Y. C.; Kuhn, L.; Schlenzig, T.; Wild, C.; Tilstra, A. (Ecology and evolution, Wiley, 2023-09-01) [Article]
    Coral energy and nutrient acquisition strategies are complex and sensitive to environmental conditions such as water flow. While high water flow can enhance feeding in hard corals, knowledge about the effects of water flow on the feeding of soft corals, particularly those pulsating, is still limited. In this study, we thus investigated the effects of feeding and water flow on the physiology of the pulsating soft coral Xenia umbellata. We crossed three feeding treatments: (i) no feeding, (ii) particulate organic matter (POM) in the form of phytoplankton and (iii) dissolved organic carbon (DOC) in the form of glucose, with four water volume exchange rates (200, 350, 500 and 650 L h−1) over 15 days. Various ecophysiological parameters were assessed including pulsation rate, growth rate, isotopic and elemental ratios of carbon (C) and nitrogen (N) as well as photo-physiological parameters of the Symbiodiniaceae (cell density, chlorophyll-a and mitotic index). Water flow had no significant effect but feeding had a substantial impact on the physiology of the X. umbellata holobiont. In the absence of food, corals exhibited significantly lower pulsation rates, lower Symbiodiniaceae cell density and lower mitotic indices compared to the fed treatments, yet significantly higher chlorophyll-a per cell and total N content. Differences were also observed between the two feeding treatments, with significantly higher pulsation rates and lower chlorophyll-a per cell in the DOC treatment, but higher C and N content in the POM treatment. Our findings suggest that the X. umbellata holobiont can be viable under different trophic strategies, though favouring mixotrophy. Additionally, the physiology of the X. umbellata may be regulated through its own pulsating behaviour without any positive or negative effects from different water flow. Therefore, this study contributes to our understanding of soft coral ecology, particularly regarding the competitive success and widespread distribution of X. umbellata. This manuscript reports on the separate and interactive effects of varying water flow regimes and feeding on the physiology of the soft coral Xenia umbellata. From our study, we concluded that X. umbellata does not receive any additional benefit from high water flow nor suffer in low flow conditions, as it may regulate autotrophy and heterotrophy via the continuous pulsation of its polyps. Furthermore, findings suggest that photosynthetic energy generation of the X. umbellata holobiont is enhanced via increased chlorophyll-a contents per cell when food is scarce. The findings of our study contribute toward understanding the ecology of soft corals and offer an additional explanation for the widespread distribution and competitive success of the mixotrophic X. umbellata.
  • Bacterioplankton dark CO2 fixation in oligotrophic waters

    Alothman, Afrah; López-Sandoval, Daffne C.; Duarte, Carlos M.; Agusti, Susana (Biogeosciences, Copernicus GmbH, 2023-08-31) [Article]
    Dark CO2 fixation by bacteria is believed to be particularly important in oligotrophic ecosystems. However, only a few studies have characterized the role of bacterial dissolved inorganic carbon (DIC) fixation in global carbon dynamics. Therefore, this study quantified the primary production (PP), total bacteria dark CO2 fixation (TBDIC fixation), and heterotrophic bacterial production (HBP) in the warm and oligotrophic Red Sea using stable-isotope labeling and cavity ring-down spectroscopy (13C–CRDS). Additionally, we assessed the contribution of bacterial DIC fixation (TBDIC %) relative to the total DIC fixation (totalDIC fixation). Our study demonstrated that TBDIC fixation increased the totalDIC fixation from 2.03 to 60.45 µg C L−1 d−1 within the photic zone, contributing 13.18 % to 71.68 % with an average value of 33.95 ± 0.02 % of the photic layer totalDIC fixation. The highest TBDIC fixation values were measured at the surface and deep (400 m) water with an average value of 5.23 ± 0.45 and 4.95 ± 1.33 µg C L−1 d−1, respectively. These findings suggest that the non-photosynthetic processes such as anaplerotic DIC reactions and chemoautotrophic CO2 fixation extended to the entire oxygenated water column. On the other hand, the percent of TBDIC contribution to totalDIC fixation increased as primary production decreased (R2=0.45, p<0.0001), suggesting the relevance of increased dark DIC fixation when photosynthetic production was low or absent, as observed in other systems. Therefore, when estimating the total carbon dioxide production in the ocean, dark DIC fixation must also be accounted for as a crucial component of the carbon dioxide flux in addition to photosynthesis.
  • Gill-associated bacteria are homogeneously selected in amphibious mangrove crabs to sustain host intertidal adaptation.

    Fusi, Marco; Ngugi, David; Marasco, Ramona; Booth, Jenny Marie; Cardinale, Massimiliano; Sacchi, Luciano; Clementi, Emanuela; Yang, Xinyuan; Garuglieri, Elisa; Fodelianakis, Stylianos; Michoud, Gregoire; Daffonchio, Daniele (Microbiome, Springer Science and Business Media LLC, 2023-08-24) [Article]
    Background: The transition from water to air is a key event in the evolution of many marine organisms to access new food sources, escape water hypoxia, and exploit the higher and temperature-independent oxygen concentration of air. Despite the importance of microorganisms in host adaptation, their contribution to overcoming the challenges posed by the lifestyle changes from water to land is not well understood. To address this, we examined how microbial association with a key multifunctional organ, the gill, is involved in the intertidal adaptation of fiddler crabs, a dual-breathing organism. Results: Electron microscopy revealed a rod-shaped bacterial layer tightly connected to the gill lamellae of the five crab species sampled across a latitudinal gradient from the central Red Sea to the southern Indian Ocean. The gill bacterial community diversity assessed with 16S rRNA gene amplicon sequencing was consistently low across crab species, and the same actinobacterial group, namely Ilumatobacter, was dominant regardless of the geographic location of the host. Using metagenomics and metatranscriptomics, we detected that these members of actinobacteria are potentially able to convert ammonia to amino acids and may help eliminate toxic sulphur compounds and carbon monoxide to which crabs are constantly exposed. Conclusions: These results indicate that bacteria selected on gills can play a role in the adaptation of animals in dynamic intertidal ecosystems. Hence, this relationship is likely to be important in the ecological and evolutionary processes of the transition from water to air and deserves further attention, including the ontogenetic onset of this association. Video Abstract.
  • Influence of environmental variables on the abundance of Synapta maculata (Holothuroidea: Synaptidae) in a multi-species seagrass meadow in the southern Red Sea of Saudi Arabia

    Abrogueña, Jeff Bogart R.; Tanita, Iwao; Anton, Andrea; Maquirang, Jean Rose H.; Duarte, Carlos M.; Woo, Sau Pinn; Berković, Buga; Roje-Busatto, Romana; Yacoubi, Lamia; Doyle, Anthony; Konji, Hatem; Al-Johani, Thamer; Chen, Jia Lun; Rabaoui, Lotfi J. (Regional Studies in Marine Science, Elsevier BV, 2023-08-23) [Article]
    The Red Sea is a harsh environment characterized by high salinity and temperature, and how benthic organisms respond to the environment therein is still relatively unexplored. Here, we looked at the intertidal population of the snake sea cucumber, Synapta maculata, found in a species-rich seagrass meadow on the southern coast of the Red Sea in Saudi Arabia. The objectives of the study were (1) to examine the changes in S. maculata abundance from spring to fall in a multi-species seagrass meadow (Halodule pinifolia, Halodule univervis, Halophila ovalis, and Halophila stipulacea) and (2) to determine the relationship between the abundance of S. maculata with the selected abiotic environmental variables (depth, salinity, temperature, pH, dissolved oxygen, wind speed, wind direction, air temperature, relative humidity, and barometric pressure). The abundance of S. maculata was assessed using three permanent 50 × 4 m belt transects. Results showed that the abundance of S. maculata was present from March to June (approximately 4 individuals per 200 m2). We observed a drastic decline in the following months that coincided with the die-off of the seagrass meadow. The abundance of S. maculata differed significantly among sampling months. Correlation analysis revealed a significant positive relationship between the abundance of S. maculata and dissolved oxygen, wind speed, and barometric pressure. At the same time, salinity, water temperature, and air temperature showed a significant negative relationship. The generalized linear model suggested salinity, pH, and dissolved oxygen were the main environmental factors that influence the population of S. maculata. Overall, the population dynamics of S. maculata in this area was driven by the combination of extreme abiotic environmental factors and the presence of seagrass meadows.
  • Ideas and perspectives: The fluctuating nature of oxygen shapes the ecology of aquatic habitats and their biogeochemical cycles – the aquatic oxyscape

    Fusi, Marco; Rigaud, Sylvain; Guadagnin, Giovanna; Barausse, Alberto; Marasco, Ramona; Daffonchio, Daniele; Régis, Julie; Huchet, Louison; Camin, Capucine; Pettit, Laura; Vina-Herbon, Cristina; Giomi, Folco (Biogeosciences, Copernicus GmbH, 2023-08-23) [Article]
    Oxygen availability is a pivotal factor for ecosystem functioning and the resistance of organisms to the effect of climate change in aquatic habitats. Although extensive work has been done to assess the effect of oxygen on marine and freshwater biota, many studies have not captured the ecological importance of oxygen variations. Overlooking the fluctuating nature of oxygen may cause potential biases in the design and implementation of management policies for aquatic habitats. Conceptual perspectives on the dynamic nature of oxygen fluctuations have been raised in the scientific community in order to enhance the understanding of the effect of oxygen on the physiology and the ecology of aquatic species as well as the biogeochemical functioning of their ecosystems. A growing number of empirical work has been outlining a novel conceptual framework that considers the magnitude of oxygen fluctuation as a key variable that explains adaptation to stress conditions. Oxygen in productive aquatic habitats shows large fluctuations at the diel scale, exposing aquatic species to conditions ranging from extreme supersaturation to anoxia. Recent research has indicated that such a fluctuation tunes the physiological plasticity of the animal in response to thermal stresses. In this paper, we provide compelling evidence based on current research that the fluctuating oxygen landscape, here defined as “oxyscape”, has an important role in aquatic animal physiology and adaptation as well as the ecosystem biogeochemistry. We propose that the oxyscape should be considered in the modelling and managing policies of aquatic ecosystems.
  • Morphological evidence of the extension of the Zabargad Transform Fault Zone to the Saudi Arabian Red Sea margin

    Petrovic, Alexander; Panara, Yuri; Vahrenkamp, Volker (Journal of the Geological Society, Geological Society of London, 2023-08-22) [Article]
    Fault locations and orientation of the Zabargad Transform Fault Zone, also called the Zabargad Fracture Zone (ZFZ) have, so far, only been delineated by satellite-based geophysical data, causing intense debate over the last decades. Newly recognized geomorphological features identified in bathymetry and lidar data from the NE Red Sea margin present the first ground evidence for the northern extent of the ZFZ. The features are aligned over 84 km starting from the Mabahiss Deep, near the spreading axis, and continue to the shallow Saudi Arabian shelf, along the northern termination of the Al Wajh carbonate platform. Analysis of the seafloor morphology revealed three geomorphic terrains: (1) a deep incised canyon feeding into the Mabahiss Deep, which is characterized by dozens of amphitheatre-shaped scarps, (2) a 22 km-wide head-scarp that follows the Al Wajh platform edge, (3) and multiple fault scars and graben-like structures on the shallow shelf. We interpret these morphological features as deformation indicators in association with the deformation processes in the ZFZ, and postulate that they represent the northern end of the ZFZ. In addition, the fault zone delineates the northwest margin of the Al Wajh carbonate platform, and most likely continues to shape it. This paper gives new insights in the interaction between fracture zones and continental margins and their role in the seafloor morphogenesis.
  • Assessing the feasibility of assisted migration of corals in the Red Sea

    Barreto, Marcelle Muniz; Schmidt-Roach, Sebastian; Zhong, Huawen; Aranda, Manuel (Frontiers in Marine Science, Frontiers Media SA, 2023-08-21) [Article]
    Climate change, and in particular the unprecedented rapid global warming, presents a major threat to corals, with warming rates potentially exceeding the adaptive capacities of most coral species. Assisted gene flow, the human facilitated introduction of temperature resilience alleles from warmer to threatened colder populations via the movement of individuals (assisted migration) or their gametes (selective breeding), has been suggested as a tool to transfer thermal adaptations among populations. Due to its strong latitudinal temperature gradient and extreme temperature conditions, the Red Sea constitutes an ideal location to investigate the potential of this strategy. Here, we relocated Porites lobata colonies from three reefs along the Saudi Arabian Red Sea with different mean sea surface temperature summer maxima (ranging from 30.9 °C in Duba, 32.5 °C in Thuwal, to 33.8 °C in Jazan) to a common garden experiment in the intermediate central location. Five colonies from each location were fragmented and deployed in situ in early summer of 2018 to investigate physiological differences in bleaching, survival, and growth. Results showed significantly higher bleaching in fragments from Duba, followed by 65% mortality. Even though no bleaching was observed in fragments from Jazan, mortality rates of around 20% indicated that other environmental parameters besides temperature might influence coral health and survival. These results suggest that assisted gene flow via translocation alone may be restricted in its success due to a lack of local adaptations to environmental conditions other than temperature. However, strategies like inter-populational breeding may overcome these limitations as they might allow producing offspring with both increased thermal tolerance and local adaptations.
  • Distribution patterns of phytoplankton groups along isoirradiance layers in oligotrophic tropical and subtropical oceans

    Latasa, Mikel; Rodríguez, Francisco; Agusti, Susana; Estrada, Marta (Progress in Oceanography, Elsevier BV, 2023-08-19) [Article]
    A pigment chemotaxonomic approach was used to find the distribution of phytoplankton groups over a wide extension of the oligotrophic tropical and subtropical Atlantic, Indian and Pacific oceans. The six sampling depths corresponded to percentages of surface irradiance, i.e. “isoirradiances”. Most of the 139 stations sampled presented a subsurface deep chlorophyll maximum (DCM). Only in 19 of the 818 samples the total chlorophyll a (TChl a) concentration was >0.5 mg m−3 and only in one >0.75 mg m−3. The composition of the phytoplankton populations showed low variability. Haptophytes and Prochlorococcus contributed most to TChl a (36% and 35%, respectively), followed by green algae (11%), Synechococcus (6.5%), pelagophytes (6.7%), dinoflagellates (3.2%) and diatoms (1.6%). Specific non-polar Chl c2 pigments were analyzed to estimate the pigment biomass of three types of haptophytes (6, 7 and 8) using CHEMTAX. Haptotophytes-8 was the most abundant (18%), while haptophytes-7 and -6 contribution was 13% and 5.2%, respectively. There was a vertical partition of the groups along the water column. Prochlorococcus, haptophytes-6 and -8, and pelagophytes presented low values in shallow and intermediate layers and a strong increase in pigment biomass at the DCM. Dinoflagellates, haptophytes-7 and green algae also with low values in the upper layers showed a sharp increase at the layer above the DCM, with similar values as in the DCM or even higher for green algae. The pigment biomass of diatoms and Synechococcus were fairly homogeneous throughout the water column. These three patterns were best reflected by estimating the contribution of each group to the TChl a concentration. The Malaspina expedition crossed some well recognized ecosystem/areas of the open ocean such as the Atlantic and Pacific equatorial upwellings, the Costa Rica and Guinea domes, the low oxygen area of the northeastern Pacific and the Great Australian Bight, for which the composition of the phytoplankton populations is provided.
  • Investigating the Biological Potency of Nitazoxanide-Based Cu(II), Ni(II) and Zn(II) Complexes Synthesis, Characterization and Anti-COVID-19, Antioxidant, Antibacterial and Anticancer Activities

    Sharfalddin, Abeer A.; Al-Younis, Inas; Emwas, Abdul-Hamid M.; Jaremko, Mariusz (Molecules, MDPI AG, 2023-08-18) [Article]
    In this work, the biological potency of nitazoxanide (NTZ) was enhanced through coordination with transition metal ions Cu(II), Ni(II), and Zn(II). Initially, complexes with a ligand-metal stoichiometry of 2:1 were successfully synthesized and characterized by spectroscopic techniques and thermogravimetric methods. Measurement of the infrared spectrum revealed the bidentate nature of the ligand and excluded the possibility of the metal ion—amide group interaction. Nuclear magnetic resonance spectra showed a reduction in the NH- intensity signal and integration, indicating the possibility of enolization and the formation of keto-enol tautomers. To interpret these results, density functional theory was utilized under B3LYP/6-311G** for the free ligand and B3LYP/LANL2DZ for the metal complexes. We used UV-Vis and fluorescence spectroscopy to understand the biological properties of the complexes. This showed stronger interactions of NTZ-Cu(II) and NTZ-Ni(II) with DNA molecules than the NTZ-Zn(II) compound, with a binding constant (Kb) for the copper complex of 7.00 × 105 M−1. Both Cu(II)- and Ni(II)-NTZ had functional binding to the SARS-CoV-2 (6LU7) protease. Moreover, all metal complexes showed better antioxidation properties than the free ligand, with NTZ-Ni(II) having the best IC50 value of 53.45 μg/mL. NTZ-Ni(II) was an effective antibacterial, with a mean inhibitory concentration of 6 μM, which is close to that of ampicillin (a reference drug). The metal complexes had moderated anticancer potencies, with NTZ-Cu(II) having IC50 values of 24.5 and 21.5 against human breast cancer cells (MCF-7) and cancerous cervical tumor cells (HeLa), respectively. All obtained complexes exhibited high selectivity. Finally, the metal ions showed a practical role in improving the biological effectiveness of NTZ molecules.
  • Data from: Mesophotic Foraminiferal-Algal Nodules play a role in the Red Sea carbonate budget

    Bracchi, V. A.; Purkis, Sam J.; Marchese, Fabio; Nolan, Megan K. B.; Terraneo, Tullia Isotta; Vimercati, Silvia; Chimienti, Giovanni; Rodrigue, Mattie; Eweida, Ameer; Benzoni, Francesca (Dryad, 2023-08-16) [Dataset]
    Free-living mesophotic Foraminiferal-Algal Nodules (FANs) have been discovered along the coast of the northern Saudi Arabian Red Sea (NEOM region) where they form a novel benthic ecosystem in mesophotic water depths on the continental shelf. Being mostly spheroidal, the nodules are transported en masse down slope, into the deep water of the basin, where they stop accreting. Radiometric dating informs that FANs can be more than two thousand years old and that they collectively contribute up to 66 g m-2 year-1 to the mesophotic benthic carbonate budget and account for at least 980 megatons of CaCO3, a substantial contribution considering the depauperate production of carbonate by other means in this light-limited environment. Our findings advance the knowledge of mesophotic biodiversity and carbonate production, and provide data that will inform conservation policies in the Saudi Arabian Red Sea.
  • Distribution of global sea turtle nesting explained from regional-scale coastal characteristics

    Christiaanse, Jakob C.; Antolínez, José A. A.; Luijendijk, Arjen P.; Athanasiou, Panagiotis; Duarte, Carlos M.; Aarninkhof, Stefan (Research Square Platform LLC, 2023-08-15) [Preprint]
    Climate change and human activity threaten sea turtle nesting beaches through increased flooding and erosion. Understanding the environmental characteristics that enable nesting can aid to preserve and expand these habitats. While numerous local studies exist, a comprehensive global analysis of environmental influences on the distribution of sea turtle nesting habitats remains largely unexplored. Here, we relate global sea turtle nesting distribution to 22 coastal indicators, spanning hydrodynamic, atmospheric, geophysical, habitat, and human processes. Using state-of-the-art global datasets and a novel 50-km-resolution hexagonal coastline grid (Coastgons), we employ machine learning to identify spatially homogeneous patterns in the indicators and correlate these to the occurrence of nesting grounds. Our findings suggest sea surface temperature, tidal range, extreme surges, and proximity to coral and seagrass habitats significantly influence global nesting distribution. Low tidal ranges and low extreme surges appear to be particularly favorable for individual species, likely due to reduced nest flooding. Other indicators, previously reported as influential (e.g., precipitation and wind speed), were not as important in our global-scale analysis. Finally, we identify new, potentially suitable nesting regions for each species, showing that on average 23% of global coastal regions between -37◦ and 48◦ latitude could be suitable for nesting, while only 6% is currently used by turtles. Our results help identify suitable nesting conditions, quantify potential hazards to global nesting habitats, and lay a foundation for nature-based solutions to preserve and potentially expand these habitats.
  • Carbon sequestration potential of transplanted mangroves and exotic saltmarsh plants in the sediments of subtropical wetlands.

    Huang, Runqiu; He, Junyu; Wang, Nan; Christakos, George; Gu, Jiali; Song, Li; Luo, Ji; Agusti, Susana; Duarte, Carlos M.; Wu, Jiaping (The Science of the total environment, Elsevier BV, 2023-08-15) [Article]
    Coastal blue carbon ecosystems offer promising benefits for both climate change mitigation and adaptation. While there have been widespread efforts to transplant mangroves from the tropics to the subtropics and to introduce exotic saltmarsh plants like Spartina alterniflora in China, few studies have thoroughly quantified the chronological records of carbon sequestration with different organic carbon (OC) sources. To understand how variations in OC sources can affect the carbon sequestration potential of coastal wetland environment over time, we conducted a study on typical islands with two scenarios: S. alterniflora invasion and mangrove transplantation. Our study determined chronological records of carbon sequestration and storage from five sediment profiles and traced changes in the OC sources using carbon stable isotope (δ13C) and C:N ratios in response to these scenarios. The S. alterniflora invasion resulted in an 84 ± 19 % increase in the OC burial rate compared to unvegetated mudflats, while mangrove transplantation resulted in a 167 ± 74 % increase in the OC burial rate compared to unvegetated mudflats. S. alterniflora and mangroves showed greater carbon sequestration potential in areas with high supplies of suspended particulate matter, while mangroves needed to grow to a certain scale to display obvious carbon sequestration benefits. In the mangrove saltmarsh ecotone, mature mangrove habitats exhibited resistance to the S. alterniflora invasion, while mangrove transplantation in the environment invaded by S. alterniflora had a significant effect on OC contribution. Besides, plant-derived OC can be exported to the surrounding environment due to the rapid turnover of sediments. The blue carbon chronosequence-based estimation of OC sources and burial rates provides a useful reference for establishing carbon accounting policies.
  • Mesophotic foraminiferal-algal nodules play a role in the Red Sea carbonate budget

    Bracchi, V. A.; Purkis, Sam J.; Marchese, Fabio; Nolan, Megan K. B.; Terraneo, Tullia Isotta; Vimercati, Silvia; Chimienti, Giovanni; Rodrigue, Mattie; Eweida, Ameer; Benzoni, Francesca (Communications Earth & Environment, Springer Science and Business Media LLC, 2023-08-14) [Article]
    During two scientific expeditions between 2020 and 2022, direct surveys led to the discovery of free-living mesophotic foraminiferal-algal nodules along the coast of the NEOM region (northern Saudi Arabian Red Sea) where they form an unexpected benthic ecosystem in mesophotic water depths on the continental shelf. Being mostly spheroidal, the nodules are transported en masse down slope, into the deep water of the basin, where they stop accreting. Radiometric dating informs that these nodules can be more than two thousand years old and that they collectively contribute up to 66 g m−2 year−1 to the mesophotic benthic carbonate budget and account for at least 980 megatons of calcium carbonate, a substantial contribution considering the depauperate production of carbonate by other means in this light-limited environment. Our findings advance the knowledge of mesophotic biodiversity and carbonate production, and provide data that will inform conservation policies in the Saudi Arabian Red Sea.
  • MEK inhibitors in cancer treatment: structural insights, regulation, recent advances and future perspectives

    Ram, Teja; Singh, Ankit Kumar; Kumar, Adarsh; Singh, Harshwardhan; Pathak, Prateek; Grishina, Maria; Khalilullah, Habibullah; Jaremko, Mariusz; Emwas, Abdul-Hamid M.; Verma, Amita; Kumar, Pradeep (RSC Medicinal Chemistry, Royal Society of Chemistry (RSC), 2023-08-10) [Article]
    MEK1/2 are critical components of the RAS–RAF–MEK–ERK or MAPK signalling pathway that regulates a variety of cellular functions including proliferation, survival, and differentiation. In 1997, a lung cancer cell line was first found to have a MEK mutation (encoding MEK2P298L). MEK is involved in various human cancers such as non-small cell lung cancer (NSCLC), spurious melanoma, and pancreatic, colorectal, basal, breast, and liver cancer. To date, 4 MEK inhibitors i.e., trametinib, cobimetinib, selumetinib, and binimetinib have been approved by the FDA and several are under clinical trials. In this review, we have highlighted structural insights into the MEK1/2 proteins, such as the αC-helix, catalytic loop, P-loop, F-helix, hydrophobic pocket, and DFG motif. We have also discussed current issues with all FDA-approved MEK inhibitors or drugs under clinical trials and combination therapies to improve the efficacy of clinical drugs. Finally, this study addressed recent developments on synthetic MEK inhibitors (from their discovery in 1997 to 2022), their unique properties, and their relevance to MEK mutant inhibition.

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