Eutrophication in freshwater has become increasingly severe around the world, resulting in phytoplankton overgrowth and benthic algae reduction. Bivalves can change the density, dominant species and community structure of phytoplankton, increase available light levels, and provide physical habitats and growth conditions for benthic algae. The nutritional composition, density, community structure, and toxin of algae affect the growth, feeding, digestion, metabolism, immunity of bivalves in return. Interactions of bivalves and algae and effects of environmental factors on these interactions need a synthesis of studies, when using bivalves as a biomanipulation tool to control eutrophication. Whether bivalves can effectively suppress phytoplankton and promote benthic algae is related to the collective filtration and excretion capacity determined by size, species, population densities of bivalves, the quantity and quality of algae, and environmental factors such as temperature, dissolved oxygen, pH, and hydrodynamic. Small scale bivalve biomanipulation experiments are mostly conducted in lakes, urban ponds, and reservoirs with some success, applying in the whole ecosystem should consider more questions such as natural conditions, selection and death or reproduction of bivalves, and ecological disturbances. This review provides new considerations for technical issues such as the sustainable cultivation of bivalves and the implementation of biomanipulation in eutrophic waters.

Hyriopsis cumingii has attracted attention because of its pearl production performance and water purification capacity. Realizing sustainable industrialized culture of H. cumingii or applying it to bivalve biomanipulation for controlling water eutrophication needs urgent studies about the selection of suitable algae and the effects of different microalgae on mussel physiology. To contrast molecular and biochemical effects of high-quality microalgal diets (Chlorella vulgaris, Navicula pelliculosa, and Cyclotella sp.) with toxic Microcystis aeruginosa on metabolism and immune physiology of H. cumingii, levels of related enzymes and genes were analyzed during the 28-day exposure period. Results showed that the Cyclotella sp. diet could significantly (p < 0.05) maintain higher levels of metabolic enzymes (glutamic oxaloacetate transaminase (GOT), glutamic pyruvate transaminase (GPT), pyruvate kinase (PK), and hexokinase (HK)) and genes (CPT1 and LDLR). C. vulgaris and N. pelliculosa treatments significantly (p < 0.05) reduced activities of these metabolic parameters. The M. aeruginosa treatment significantly (p < 0.05) enhanced levels of immune enzymes (alkaline phosphatase (AKP), superoxide dismutase (SOD), and catalase (CAT)) and genes (HcIL-17 and IAP) on day 1 or 7, and there was a significant (p < 0.05) reduction on day 28. Results suggested that Cyclotella sp. was the suitable algae for H. cumingii, followed by C. vulgaris and N. pelliculosa, and toxic algae caused metabolic disorders, immune injury, and poor physiological status. The study has practical significance in the sustainable cultivation of H. cumingii and provides a theoretical basis for bivalve biomanipulation in eutrophic water.

Mast cells play a central role in innate and adaptive immunity by releasing pre-formed and de novo synthesized mediators, which include microRNAs. Although miRNAs have been confirmed to function in cell proliferation, differentiation, apoptosis, and the immune response, their functions are still limited in mast cells degranulation. Here, we survey miRNA expression profiles in activated mouse bone marrow-derived mast cells (BMMCs) with a miRNA microarray and compare the profiles to those from resting BMMCs. Partial miRNAs were selected for confirmation by qPCR, and let-7i was selected for function discover in mast cell degranulation process. TargetScan Mouse database were used for target genes prediction, gene ontology (GO) were used for gene molecular function classifications, and Cytoscape software were used to construct gene network of degranulation. We found 13 up-regulated miRNAs and 7 down-regulated miRNAs in DNP activated BMMCs by miRNA microarray; and let-7b, let-7c, let-7d, let-7f, let-7i, and miR-652 were up-regulated, and miR-296-3p was down-regulated in DNP-stimulated BMMCs by qPCR. In the function research, let-7i can inhibit mast cell degranulation by suppress Exco8 expression. Overall, the data indicate that miRNAs participate in mast cell activation, especial for mast cell degranulation process.