Studies on the hemolytic activity of tentacle extracts of jellyfish Rhopilema esculentum Kishinouye: Application of orthogonal test

Identification of cardiorespiratory toxic components of Nemopilema nomurai jellyfish venom using sequential chromatography methods

Jellyfish stings pose a significant threat to humans in coastal areas worldwide, with venomous jellyfish species stinging millions of individuals annually. Nemopilema nomurai is one of the largest jellyfish species, with numerous tentacles rich in nematocysts. N. nomurai venom (NnV) is a complex mixture of proteins, peptides, and small molecules that serve as both prey-capture and defense mechanisms. Yet, the molecular identity of its cardiorespiratory and neuronal toxic components of NnV has not been clearly identified yet. Here, we isolated a cardiotoxic fraction, NnTP (Nemopilema nomurai toxic peak), from NnV using chromatographic methods. In the zebrafish model, NnTP exhibited strong cardiorespiratory and moderate neurotoxic effects. LC-MS/MS analysis identified 23 toxin homologs, including toxic proteinases, ion channel toxins, and neurotoxins. The toxins demonstrated a synergistic effect on the zebrafish, leading to altered swimming behavior, hemorrhage in the cardiorespiratory region, and histopathological changes in organs such as the heart, gill, and brain. These findings provide valuable insights into the mechanisms underlying the cardiorespiratory and neurotoxic effects of NnV, which could be useful in developing therapeutic strategies for venomous jellyfish stings.

Comprehensive Proteome Reveals the Key Lethal Toxins in the Venom of Jellyfish Nemopilema nomurai

Jellyfish stings are a major threat to human beings in coastal areas of the world. Each year, hundreds of thousands of victims are stung by venomous jellyfish. Nemopilema nomurai is a dangerous species with a large number of victims including many deaths. N. nomurai venom is a complex cocktail that is rich in proteins and peptides, and it is secreted by nematocysts for prey or defense. Previous studies have identified hundreds of toxins in the venom of N. nomurai; however, it is unclear which toxin(s) is responsible for lethality. Herein, we isolated the lethal fraction (NnLF) from N. nomurai venom with multiple chromatography. NnLF showed strong lethality to mice, and the toxicology results were consistent with the clinical symptoms of dead patients after N. nomurai sting, which indicated that NnLF contained the key lethal toxins in the venom. Subsequently, proteomic analysis was performed to identify the toxins in NnLF, and a total of 13 toxin homologues were identified, including phospholipase, potassium channel inhibitor, hemolysin, thrombin, etc. Moreover, in vitro toxicity assays further verified the phospholipase A₂ and hemolytic activity of NnLF. These results revealed that cell membrane-targeted toxins, including channel-forming toxins, potassium channel inhibitors, and especially phospholipases, played very important roles in the lethality of N. nomurai sting. Moreover, blood toxins such as thrombin-like toxin and hemolysins might be synergistically involved in lethality. These findings advance the understanding of lethality caused by N. nomurai sting and will be significant for the development of drugs to treat this jellyfish sting in the future.

Unique Diversity of Sting-Related Toxins Based on Transcriptomic and Proteomic Analysis of the Jellyfish Cyanea capillata and Nemopilema nomurai (Cnidaria: Scyphozoa)

The scyphozoan jellyfish Cyanea capillata and Nemopilema nomurai are common blooming species in China. They possess heterogeneous nematocysts and produce various types of venom that can elicit diverse sting symptoms in humans. However, the differences in venom composition between the two species remain unclear. In this study, a combined transcriptomic and proteomic approach was used to identify and compare putative toxins in penetrant nematocysts isolated from C. capillata and N. nomurai. A total of 53 and 69 putative toxins were identified in C. capillata nematocyst venom (CnV) and N. nomurai nematocyst venom (NnV), respectively. These sting-related toxins from both CnV and NnV could be grouped into 10 functional categories, including proteinases, phospholipases, neurotoxins, cysteine-rich secretory proteins (CRISPs), lectins, pore-forming toxins (PFTs), protease inhibitors, ion channel inhibitors, insecticidal components, and other toxins, but the constituent ratio of each toxin category varied between CnV and NnV. Metalloproteinases, proteases, and pore-forming toxins were predominant in NnV, representing 27.5%, 18.8%, and 8.7% of the identified venom proteins, respectively, while phospholipases, neurotoxins, and proteases were the top three identified venom proteins in CnV, accounting for 22.6%, 17.0%, and 11.3%, respectively. Our findings provide comprehensive information on the molecular diversity of toxins from two common blooming and stinging species of jellyfish in China. Furthermore, the results reveal a possible relationship between venom composition and sting consequences, guiding the development of effective treatments for different jellyfish stings.

β adrenergic receptor/cAMP/PKA signaling contributes to the intracellular Ca2+ release by tentacle extract from the jellyfish Cyanea capillata

Background

Intracellular Ca²⁺ overload induced by extracellular Ca²⁺ entry has previously been confirmed to be an important mechanism for the cardiotoxicity as well as the acute heart dysfunction induced by jellyfish venom, while the underlying mechanism remains to be elucidated.

Methods

Under extracellular Ca²⁺-free or Ca²⁺-containing conditions, the Ca²⁺ fluorescence in isolated adult mouse cardiomyocytes pre-incubated with tentacle extract (TE) from the jellyfish Cyanea capillata and β blockers was scanned by laser scanning confocal microscope. Then, the cyclic adenosine monophosphate (cAMP) concentration and protein kinase A (PKA) activity in primary neonatal rat ventricular cardiomyocytes were determined by ELISA assay. Furthermore, the effect of propranolol against the cardiotoxicity of TE was evaluated in Langendorff-perfused rat hearts and intact rats.

Results

The increase of intracellular Ca²⁺ fluorescence signal by TE was significantly attenuated and delayed when the extracellular Ca²⁺ was removed. The β adrenergic blockers, including propranolol, atenolol and esmolol, partially inhibited the increase of intracellular Ca²⁺ in the presence of 1.8 mM extracellular Ca²⁺ and completely abolished the Ca²⁺ increase under an extracellular Ca²⁺-free condition. Both cAMP concentration and PKA activity were stimulated by TE, and were inhibited by the β adrenergic blockers. Cardiomyocyte toxicity of TE was antagonized by β adrenergic blockers and the PKA inhibitor H89. Finally, the acute heart dysfuction by TE was antagonized by propranolol in Langendorff-perfused rat hearts and intact rats.

Conclusions

Our findings indicate that β adrenergic receptor/cAMP/PKA signaling contributes to the intracellular Ca²⁺ overload through intracellular Ca²⁺ release by TE from the jellyfish C. capillata.

Combined proteomics and transcriptomics identifies sting-related toxins of jellyfish Cyanea nozakii

Jellyfish sting has become a worldwide issue of critical concern to human health and safety in coastal areas in recent decades. Cyanea nozakii is one of the dominant blooming species and dangerous stingers in China. However, it remains unclear how many and what types of toxins are present in the venom. So, we used a combined transcriptomics and proteomics approach to investigate the venom composition of jellyfish C. nozakii. In total 4,608,524 Illumina valid reads were obtained to de novo assemble to 40,434 unigenes in the transcriptomics analysis. And, a total of 311,635 MS/MS spectra with 12,247 unique MS/MS spectra were generated to 1556 homologous proteins in the proteomics analysis. 174 potential toxin proteins were identified, with 27 proteins homology to the toxins from venomous animals, including phospholipase A2, zinc metalloproteinase-disintegrin agkistin, serine protease inhibitor, plancitoxin-1, alpha-latrocrustotoxin-Lt1a, etc. This study described the transcriptomics and venom proteomics of jellyfish C. nozakii for the first time. Our findings provide a comprehensive understanding of the venom composition of C. nozakii. Furthermore, the results may also be very helpful for the discovery of novel bioactive proteins, as well as the development of effective treatments for jellyfish sting in the future.

BIOLOGICAL SIGNIFICANCE

Jellyfish Cyanea nozakii is one of the most dangerous stingers in the coast of china. Hundreds of thousands of people would be stung every year and victims suffered a severe pain, itch, swelling, inflammation, wheal and even more serious consequence. However, it remains unclear how many and what types of toxins are present as well as the relationship between the clinical symptoms and toxins. Our combined transcriptomics and proteomics findings can provide a comprehensive understanding of the venom composition of C. nozakii and will also be helpful for the development of effective treatments for jellyfish sting in the future.

The Corrosion Characteristics and Tensile Behavior of Reinforcement under Coupled Carbonation and Static Loading

This paper describes the non-uniform corrosion characteristics and mechanical properties of reinforcement under coupled action of carbonation and static loading. The two parameters, namely area-box (AB) value and arithmetical mean deviation (R_a), are adopted to characterize the corrosion morphology and pitting distribution from experimental observations. The results show that the static loading affects the corrosion characteristics of reinforcement. Local stress concentration in corroded reinforcement caused by tensile stress drives the corrosion pit pattern to be more irregular. The orthogonal test results from finite element simulations show that pit shape and pit depth are the two significant factors affecting the tensile behavior of reinforcement. Under the condition of similar corrosion mass loss ratio, the maximum plastic strain of corroded reinforcement increases with the increase of R_a and load time-history significantly.

Application of Gurson-Tvergaard-Needleman constitutive model to the tensile behavior of reinforcing bars with corrosion pits

Based on meso-damage mechanics and finite element analysis, the aim of this paper is to describe the feasibility of the Gurson–Tvergaard–Needleman (GTN) constitutive model in describing the tensile behavior of corroded reinforcing bars. The orthogonal test results showed that different fracture pattern and the related damage evolution process can be simulated by choosing different material parameters of GTN constitutive model. Compared with failure parameters, the two constitutive parameters are significant factors affecting the tensile strength. Both the nominal yield and ultimate tensile strength decrease markedly with the increase of constitutive parameters. Combining with the latest data and trial-and-error method, the suitable material parameters of GTN constitutive model were adopted to simulate the tensile behavior of corroded reinforcing bars in concrete under carbonation environment attack. The numerical predictions can not only agree very well with experimental measurements, but also simplify the finite element modeling process.