Western Baltic spring spawning herring (Clupea harengus, L.) is a commercially important fish stock currently suffering a strong decline. Larval survival is essential for stock recruitment and can be ...substantially decreased by predation. The comb jelly Mnemiopsis leidyi A. Agassiz, 1865, is a lobate ctenophore which is invasive to the Baltic Sea and a known ichthyoplankton predator. However, predation on herring larvae in the Baltic Sea by M. leidyi has not been studied since its initial establishment in 2006. To address this knowledge gap, we conducted feeding experiments to investigate (1) the predation capability of M. leidyi on herring yolk-sac larvae, and (2) the influence of larval age, (3) predator size and (4) the presence of alternative prey on the clearance rate of M. leidyi on herring yolk-sac larvae. Our results showed that M. leidyi exhibited the ability to capture and digest herring larvae. The clearance rates of M. leidyi on herring larvae decreased with larval age and increased with predator size, while the presence of alternative prey had no effect on clearance rates. This finding suggests that M. leidyi can efficiently consume herring yolk-sac larvae under laboratory conditions. However, further investigations using mesocosm or field studies are necessary to evaluate the potential impact of M. leidyi on the mortality and recruitment of herring yolk-sac larvae under Baltic Sea field conditions.
•Mnemiopsis leidyi is capable of catching and digesting herring yolk-sac larvae.•Predation on herring larvae is decreasing with prey age and increasing with predator size.•Predation of M. leidyi on herring larvae is not affected by the presence of alternative natural prey represented by the copepod Acartia tonsa.•Substantial predation of M. leidyi on yolk-sac herring larvae may occur in the field, when both overlap spatially and temporarily.
Soft actuators that exhibit large deformation and can move at a fast speed in response to external stimuli have been in high demand for biomimetic applications. In this paper, we propose a convenient ...approach to fabricate a reversible and thermal-responsive composite hydrogel. Under the irradiation of visible light, the striped hydrogel can bend at a speed of up to 65.72°/s with carbon nanotubes loaded at a concentration of 3 mg/mL. A jellyfish-like miniature soft robot is made using this hydrogel. When driven by visible light, the robot can move at a maximum speed of 3.37 mm/s. Besides swimming, other motion modes, including walking and jumping, are also achieved by the robot. In addition, the robot can perform directional transportation of tiny objects. As a new actuation approach for the research of jellyfish-like miniature soft robots, this work is of great significance to the development of flexible bionic robots. Moreover, this work also offers some important insights into the research of biomimetic robots driven by visible light.
•A homogenous polysaccharide (JSP-11) was isolated from jellyfish.•The structural features of JSP-11 were characterized.•The activation of macrophages by JSP-11 and the related mechanism were ...studied.
A new polysaccharide (JSP-11) with a molecular weight of 1.25×106Da was extracted and purified from jellyfish. Monosaccharide analysis showed that JSP-11 was composed of mannose, galactose and glucuronic acid with a molar ratio of 2.18:1.00:1.94. According to the analysis of fourier transform-infrared spectroscopy, methylation analysis, and NMR spectroscopy, JSP-11 was determined to contain a linear backbone which consisted of (1→3,6)-linked β-d-Manp and (1→6)-linked β-d-Galp. The branch of (1→)-linked α-d-GlcpA was attached to the C-3 position of (1→3,6)-linked β-d-Manp in the backbone. The immunomodulatory assay exhibited that JSP-11 could significantly enhance the viability of RAW 264.7 macrophage cells, and promote the release of NO, TNF-α, and IL-1β via activating NF-κB, MAPKs and PI3K/Akt signal pathways.
Radiation (e.g., nuclear leakage) is a common harmful factor in the ocean that potentially affects the microbial community in nearby benthic hosts such as jellyfish polyps, which is essential for the ...maintenance of jellyfish populations and high-quality medusae. After comparison with the microbial community of medusae, the effect of 60Co-γ on the microbial community in Aurelia coerulea polyps was dynamically tested using 16S rRNA gene sequencing. Our results suggested that Proteobacteria (76.19 ± 3.24%), Tenericutes (12.93 ± 3.20%) and Firmicutes (8.33 ± 1.06%) are most abundant in medusae, while Proteobacteria (29.49 ± 2.29%), Firmicutes (46.25 ± 5.59%), and Bacteroidetes (20.16 ± 2.65%) are the top three phyla in polyps. After 60Co-γ radiation, the proportion of Proteobacteria increased from 29.49 ± 2.29% to 59.40 ± 3.09% over 5 days, while that of Firmicutes decreased from 46.25 ± 5.59% to 13.58 ± 3.74%. At the class level, Gammaproteobacteria continually increased during the 5 days after radiation exposure, whereas Bacilli declined, followed by partial recovery, and Alphaproteobacteria and Flavobacteriia remained almost unchanged. Intriguingly, Staphylococcus from Firmicutes and three other genera, Rhodobacter, Vibrio, and Methylophaga, from Proteobacteria greatly overlapped according to their KEGG functions. It is concluded that the microbial community in A. coerulea polyps is distinct from that in the medusae and is greatly affected by 60Co-γ exposure, with a growth (0–3 d) period and a redistribution (3–5 d) period. The dynamic change in the microbial community is probably an important self-defense process in response to external interference that is regulated by the host's physiological characteristics and the intense interspecific competition among symbiotic microbes with similar functions and functional redundancies.
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•The microbial community in Aurelia coerulea polyps is distinct from that in medusae.•The impacts of radiation on the bacterial community of Aurelia coerulea polyps were clarified.•There was a significant negative correlation between Bacilli and Gammaproteobacteria after radiation.•The self-defense of hosts to external interference may drive the dynamic change of the microbial community after radiation.
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•Bioinspired jellyfish-like carbon/manganese nanomotor is developed.•Near-infrared light and H2O2 dual-propulsion is achieved.•Cooperation of dual-propulsion and •OH catalytic ...activity actively enhances tumor chemodynamic therapy.
Chemodynamic therapy (CDT), which catalyzes the production of highly toxic reactive oxygen species (ROS), has been widely used in tumor therapy in the past five years. However, most of the current nanomaterials for CDT are difficult to penetrate into the tumor effectively due to the lack of motility, resulting in an unsatisfactory CDT effect. Herein, bioinspired jellyfish-like carbon/manganese nanomotors (JCMNs) are designed to achieve hydrogen peroxide (H2O2) and NIR light dual-propulsion for the enhanced CDT therapy. Based on the jellyfish-like asymmetric structure, the manganese component can catalyze H2O2 to generate chemical concentration gradient, propelling JCMNs to dynamically generate ROS in cells by self-diffusiophoresis. In addition, the carbon component of JCMNs can absorb near-infrared (NIR) light to produce a temperature gradient, driving JCMNs to enhance tumor penetration by self-thermophoresis. The combination of chemical and NIR light propulsions significantly improves the efficiency of tumor CDT, revealing that it should be a reasonable strategy to promote the development of nanobiomedicine by endowing nanosystems with propulsion capacity.
Jellyfish, with their tetraradial symmetry, offer a novel paradigm for addressing patterning mechanisms during regeneration. Here we show that an interplay between mechanical forces, cell migration ...and proliferation allows jellyfish fragments to regain shape and functionality rapidly, notably by efficient restoration of the central feeding organ (manubrium). Fragmentation first triggers actomyosin-powered remodeling that restores body umbrella shape, causing radial smooth muscle fibers to converge around 'hubs' which serve as positional landmarks. Stabilization of these hubs, and associated expression of
, depends on the configuration of the adjoining muscle fiber 'spokes'. Stabilized hubs presage the site of the manubrium blastema, whose growth is Wnt/β-catenin dependent and fueled by both cell proliferation and long-range cell recruitment. Manubrium morphogenesis is modulated by its connections with the gastrovascular canal system. We conclude that body patterning in regenerating jellyfish emerges mainly from local interactions, triggered and directed by the remodeling process.
Mesopelagic fish form an important link between zooplankton and higher trophic levels in Southern Ocean food webs, however their diets are poorly known. Most of the dietary information available ...comes from morphological analysis of stomach contents and to a lesser extent fatty acid and stable isotopes. DNA sequencing could substantially improve our knowledge of mesopelagic fish diets, but has not previously been applied. We used high-throughput DNA sequencing (HTS) of the 18S ribosomal DNA and mitochondrial cytochrome oxidase I (COI) to characterise stomach contents of four myctophid and one bathylagid species collected at the southern extension of the Kerguelen Plateau (southern Kerguelen Axis), one of the most productive regions in the Indian sector of the Southern Ocean. Diets of the four myctophid species were dominated by amphipods, euphausiids and copepods, whereas radiolarians and siphonophores contributed a much greater proportion of HTS reads for Bathylagus sp. Analysis of mitochondrial COI showed that all species preyed on Thysanoessa macrura, but Euphausia superba was only detected in the stomach contents of myctophids. Size-based shifts in diet were apparent, with larger individuals of both bathylagid and myctophid species more likely to consume euphausiids, but we found little evidence for regional differences in diet composition for each species over the survey area. The presence of DNA from coelenterates and other gelatinous prey in the stomach contents of all five species suggests the importance of these taxa in the diet of Southern Ocean mesopelagics has been underestimated to date. Our study demonstrates the use of DNA-based diet assessment to determine the role of mesopelagic fish and their trophic position in the Southern Ocean and inform the development of ecosystem models.
This study focused on the bloom-developing process of the giant jellyfish, Nemopilema nomurai, on phytoplankton and microzooplankton communities. Two repeated field observations on the jellyfish ...bloom were conducted in June 2012 and 2014 in the southern Yellow Sea where blooms of N. nomurai were frequently observed. We demonstrated that the bloom was made up of two stages, namely the developing stage and the mature stage. Total chlorophyll a increased and the concentrations of inorganic nutrients decreased during the developing stage, while both concentrations maintained stable and at low levels during the mature stage. Our analysis revealed that phosphate excreted by growing N. nomurai promoted the growth of phytoplankton at the developing stage. At the mature stage, size compositions of microzooplankton were altered and tended to be smaller via a top-down process, while phytoplankton compositions, affected mainly through a bottom-up process, shifted to be less diatoms and cryptophytes but more dinoflagellates.
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•Elucidation on effects of jellyfish blooming process on plankton communities.•Jellyfish blooms consist of two stages, the developing stage and the mature stage.•Growing jellyfish compensated for P deficiency and promoted phytoplankton growth.•Jellyfish blooms result in smaller sizes of microzooplankton via top-down control.•Jellyfish blooms lead to less diatoms and cryptophytes but more dinoflagellates.
•A Multi-Objective Jellyfish Search (MOJS) algorithm is developed to solve problems optimally with multiple objectives.•The proposed algorithm was tested on 20 mathematical benchmark functions, and ...compared with six well-known metaheuristic optimization algorithms.•Three structural design problems (25-bar tower, 160-bar tower and 942-bar tower) were efficiently solved by MOJS.•Mathematical tests and the structural design problems demonstrate the merits of MOJS in solving real problems with best Pareto-optimal fronts.
This study develops a Multi-Objective Jellyfish Search (MOJS) algorithm to solve engineering problems optimally with multiple objectives. Lévy flight, elite population, fixed-size archive, chaotic map, and the opposition-based jumping method are integrated into the MOJS to obtain the Pareto optimal solutions. These techniques are employed to define the motions of jellyfish in an ocean current or a swarm in multi-objective search spaces. The proposed algorithm is tested on 20 multi-objective mathematical benchmark problems, and compared with six well-known metaheuristic optimization algorithms (MOALO, MODA, MOEA/D, MOGWO, MOPSO, and NSGA-II). The results thus obtained indicate that the MOJS finds highly accurate approximations to Pareto-optimal fronts with a uniform distribution of solutions for the test functions. Three constrained structural problems (25-bar tower design, 160-bar tower design, and 942-bar tower design) of minimizing structural weight and maximum nodal deflection were solved using MOJS. The visual analytics demonstrates the merits of MOJS in solving real engineering problems with best Pareto-optimal fronts. Accordingly, the MOJS is an effective and efficient algorithm for solving multi-objective optimization problems.
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