Hao Zheng,Xia Liu,Guocheng Liu,Xianxiang Luo,Fengmin Li,Zhenyu Wang
Biochar (BC) and activated carbon (AC) amendments have been applied to remediate contaminated sediments because of their benefits in reducing toxicity and/or the bioavailability of contaminants. However, their ecotoxicity to benthic organisms, which are not well understood, should be carefully considered before their practical application. Therefore, a wood-derived BC (WBC) or a coconut shell-derived AC (CAC) was incorporated into a marine sediment at 5% (dw%) to investigate their effects on the growth and nutritional quality of a marine clam ( Meretrix meretrix ). CAC and WBC had no effect on the pH and calcium content of the sediment, but significantly increased the electrical conductivity (EC) and total organic carbon (TOC), and decreased the dissolved organic carbon (DOC). After 28 days of cultivation, WBC reduced the shell growth of the clam by 36.4%, and CAC reduced the soft tissues of the clam by 9.05%. This was probably because WBC and CAC adsorb organic matters and the feeding algae may colonize within their pores, thus, reducing food bioavailability for the clams. Water extracts of CAC and WBC had negligible effects on soft tissue growth, whereas the CAC extract inhibited the growth of clam shells by 57.9%. WBC and CAC had little influence on the nutritional quality of clams, including moisture, crude protein , and crude lipid contents. These findings are helpful to understand the ecotoxicological risks of BC and AC amendments to benthic organisms when used for the remediation of contaminated marine sediments.
Xiaorong Xu,Kai Liao,Peng Shi,Jilin Xu,Zhaoshou Ran,Chengxu Zhou,Lin Zhang,Jiayi Cao,Xiaojun Yan
Bivalve lectins perform a crucial function in recognition of foreign particles, such as microalgae and pathogenic bacteria. In this study, a novel C-type lectin form Sinonovacula constricta ( ScCL ) was characterized. The full-length cDNA of ScCL was 1645 bp, encoding a predicted polypeptide of 273 amino acids with one typical carbohydrate-recognition domain. ScCL has the highest similarity and closest phylogenetic relationship with the C-type lectin from Solen grandis . Real-time PCR analysis showed that ScCL was expressed in all tested tissues, with the highest expression in the foot and the lowest expression in hemocytes . Agglutination activity of ScCL was Ca 2+ -independent. ScCL showed the strongest agglutination on Chlorella vulgaris , the modest agglutination on Platymonas subcordiformis , Nannochloropsis sp., and Thalassiosira pseudonana , the weakest agglutination on Chaetoceros sp., and no agglutination on Isochrysis zhanjiangensis . Meanwhile, agglutination tests and western blot analysis revealed that the recombinant ScCL protein could agglutinate Staphylococcus aureus and Vibrio harveyi , but could not agglutinate Vibrio anguillarum , Bacillus cereus , or Vibrio parahaemolyticus . Furthermore, ScCL had a high binding activity with LPS and mannose , a low binding activity with LTA, and no binding activity with PGN. The expression of ScCL in the gill of S. constricta fed with C. vulgaris and T. pseudonana was significantly increased at 1 and/or 3 h. After injection with S. aureus , the expression of ScCL in the gill was significantly increased at 3, 6, and 24 h. These results indicated that ScCL was involved in food particle recognition and immunity of S. constricta .
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