Phenoloxidase Activity of Hemocyanin in Whiteleg Shrimp Penaeus vannamei: Conversion, Characterization of Catalytic Properties, and Role in Postmortem Melanosis

2008 ◽  
Vol 56 (15) ◽  
pp. 6454-6459 ◽  
Author(s):  
Fernando L. García-Carreño ◽  
Keni Cota ◽  
María A. Navarrete del Toro
Keyword(s):  
Catalytic Properties ◽  
Penaeus Vannamei ◽  
Phenoloxidase Activity ◽  
Whiteleg Shrimp

scholarly journals Innate immune responses of whiteleg shrimp (Penaeus vannamei) experimentally infected with acute hepatopancreas necrosis disease-causing Vibbrio parahaemolyticus

2019 ◽  
Vol 18 (01) ◽  
pp. 80-88
Author(s):  
Tuan V. Vo
Keyword(s):  
Immune Responses ◽  
Respiratory Burst ◽  
Innate Immune ◽  
Burst Activity ◽  
Penaeus Vannamei ◽  
Innate Immune Responses ◽  
Respiratory Burst Activity ◽  
Phenoloxidase Activity ◽  
Whiteleg Shrimp ◽  
Total Haemocyte Count

The innate immune responses of the whiteleg shrimps (Penaeus vannamei) experimentally challenged with V. parahaemolyticus by immersion were investigated for a period of 120 h. The results showed that the lethal dose 50% (LD50) of shrimps (2 - 3 g) challenged with V. parahaemolyticus was 4.7 × 106 CFU/mL. No significant differences in immune parameters were observed between the control and challenged group right after challenge (0 hpi). However, the total haemocyte count, phenoloxidase activity and respiratory burst activity were decreased in the challenged shrimps after 24 and 48 hpi and significantly different from those in the control shrimps (P < 0,05). At 72, 96 and 120 hpi, there were no significant differences in the total haemocyte count, phenoloxidase activity and respiratory burst activity between two treatments. The observations of this study showed that the innate immune responses of the whiteleg shrimp were decreased due to the infection by V. parahaemolyticus.

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

Characterization of a novel shrimp pathogen, Vibrio brasiliensis , isolated from Pacific white shrimp, Penaeus vannamei

2021 ◽  
Author(s):  
Ge Li ◽  
Guosi Xie ◽  
Hailiang Wang ◽  
Xiaoyuan Wan ◽  
Xinshu Li ◽  
...  
Keyword(s):  
Pacific White Shrimp ◽  
White Shrimp ◽  
Penaeus Vannamei

Preparation and Application of Lead Dioxide Electrode for Zinc Electrolysis

2013 ◽  
Vol 785-786 ◽  
pp. 1125-1129
Author(s):  
Xiao Yong Yang ◽  
Pei Xian Zhu ◽  
Yun Sen Si
Keyword(s):  
Surface Characterization ◽  
Catalytic Properties ◽  
Lead Dioxide ◽  
Manufacturing Cost ◽  
X Ray Diffraction ◽  
Simulation Test ◽  
X Ray ◽  
Zinc Smelter ◽  
Lead Dioxide Electrode

According to the process of anodic oxygen evolution in sulfate system for zinc electrolysis,Ti-base lead dioxide electrode can be prepared to use in this case.The surface characterization of the electrode was studied by Scanning electron microscopy(SEM) and X-ray diffraction(XRD).The electrode lifetime was tested in 1mol/L H2SO4solution at 60°C,and the electro-catalytic properties was examined by polarization curves.Then these samples was enlarged and simulation test was conducted at Mengzi marriage zinc smelter in Yunnan.The results show that the electro-catalytic properties is better and the electrodes lifetime is longer compared to the traditional lead electrode.Moreover,it has a significant effect in reducing energy consumption, manufacturing cost and improving the production and grade of zinc.

scholarly journals Characterization of Dye-decolorizing Peroxidase (DyP) fromThermomonospora curvataReveals Unique Catalytic Properties of A-type DyPs

2015 ◽  
Vol 290 (38) ◽  
pp. 23447-23463 ◽  
Author(s):  
Chao Chen ◽  
Ruben Shrestha ◽  
Kaimin Jia ◽  
Philip F. Gao ◽  
Brian V. Geisbrecht ◽  
...  
Keyword(s):  
Catalytic Properties
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