Urolithin A ameliorates obesity-induced metabolic cardiomyopathy in mice via mitophagy activation.

Metabolic cardiomyopathy (MC) is characterized by intracellular lipid accumulation and utilizing fatty acids as a foremost energy source, thereby leading to excess oxidative stress and mitochondrial dysfunction. There is no effective therapy available yet. In this study we investigated whether defective mitophagy contributed to MC and whether urolithin A (UA), a naturally occurring microflora-derived metabolite, could protect against MC in experimental obese mice. Mice were fed high fat diet for 20 weeks to establish a diet-induced obese model. We showed that mitochondrial autophagy or mitophagy was significantly downregulated in the heart of experimental obese mice. UA (50 mg·kg-1·d-1, for 4 weeks) markedly activated mitophagy and ameliorated MC in obese mice by gavage. In PA-challenged H9C2 cardiomyocytes, UA (5 µM) significantly increased autophagosomes and decreased autolysosomes. Furthermore, UA administration rescued PINK1/Parkin-dependent mitophagy and relieved mitochondrial defects in the heart of obese mice, which led to improving cardiac diastolic function and ameliorating cardiac remodelling. In PA-challenged primarily isolated cardiomyocytes, both application of mitophagy inhibitor Mdivi-1 (15 µM) and silencing of mitophagy gene Parkin blunted the myocardial protective effect of UA. In summary, our data suggest that restoration of mitophagy with UA ameliorates symptoms of MC, which highlights a therapeutic potential of UA in the treatment of MC.

Algicidal bacterium CZBC1 inhibits the growth of Oscillatoria chlorina, Oscillatoria tenuis, and Oscillatoria planctonica.

Frequent harmful cyanobacteria blooms limit the sustainable development of aquaculture. Algicidal bacteria can efficiently control harmful algae without secondary pollution. The algicidal bacteria CZBC1 can lyse Oscillatoria spp. and other harmful cyanobacteria, but its effector mechanism and algicidal threshold are unknown. In this study, we examined the algicidal effect of CZBC1 on O. chlorina, O. tenuis, and O. planctonica by microscopic enumeration and scanning electron microscopy observation. Then, we examined the alginolytic effects of CZBC1 (concentrations 103-106 colony forming units (cfu)/mL) on these three species (concentrations 103-106 cells/mL) to determine the effective concentrations of CZBC1 for Oscillatoria spp. alginolysis. Results showed that CZBC1 can directly lyse O. chlorina and O. tenuis but indirectly lyse O. planctonica. When the initial concentration of CZBC1 was 106 cfu/mL, alginolytic effects were high for all three species at all concentrations, and the alginolytic rate could reach 100% in 3-9 days. When the initial concentration of CZBC1 was lower (103 cfu/mL), its inhibitory effects were delayed by 2-5 days, but the cell counts were significantly decreased compared with the control, evidencing significant alginolysis. In addition, the higher the concentration of the algicidal bacteria suspension, the more significant the alginolytic effects. Our results indicate that CZBC1 has different alginolytic mechanisms for O. chlorina, O. tenuis, and O. planctonica, and that different initial concentrations of CZBC1 have different alginolytic effects on these algal species.

Effect of guava leaves on growth and the non-specific immune response of Penaeus monodon.

Guava (Psidium guajava L.) leaf extracts have antiviral and antibacterial activity against shrimp pathogens such as yellow-head virus (YHV), white spot syndrome virus (WSSV), and Vibrio harveyi, which make it a potential water disinfectant for use in shrimp culture. In this study, the safety of guava leaf supplementation in shrimp was evaluated by studying its influence on growth and the non-specific immune response of Penaeus monodon. Six diets containing different levels of guava leaves (0% [basal diet], 0.025% [G1], 0.05% [G2], 0.1% [G3], 0.2% [G4], and 0.4% [G5]) were fed to groups of shrimp (1.576 ± 0.011 g body weight) in triplicate for 56 days. Growth performance (final body weight, WG, PWG, SGR) of shrimp fed guava leaf diets was significantly higher (P < 0.05) than that of shrimp fed on the basal diet. The G1 diet resulted in the highest body weight gain (308.44%), followed by the G2 (295.45%), G3 (283.05%), G5 (281.29%), G4 (276.11%), and finally the basal diet (214.58%). Survival of shrimp in the G1 diet group was higher than that of shrimp in the control and the other experimental groups; however, no statistical differences (P > 0.05) were found. Dietary supplementation with guava leaf improved the activities of prophenoloxidase (PO) and nitric oxide synthase (NOS) in serum, and of superoxide dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (AKP), and lysozyme (LSZ) both in serum and hepatopancreas of shrimp. In the experimental groups, the activities of these enzymes followed a similar pattern of change; they increased initially at low levels of dietary supplementation and then decreased with increasing concentrations of dietary guava leaf. Serum PO and SOD activities in shrimp fed the G1 diet reached 7.50 U ml(-1) and 178.33 U ml(-1), respectively, with PO activity being significantly higher than in controls. In shrimp fed the G1 diet, SOD, ACP, and AKP activities in hepatopancreas were significantly higher than in the controls, reaching 57.32 U g(-1), 23.28 U g(-1), and 19.35 U g(-1) protein, respectively. The highest activities of serum ACP, AKP, LSZ, and of hepatopancreas LSZ, were observed in the G3 diet group. Total nitric oxide synthase (TNOS) activity was highest (64.80 U ml(-1)) in the G4 diet group, which was significantly higher than that observed in the control group. These results suggest that dietary guava leaf supplementation could enhance the growth performance and non-specific immune response of P. monodon. Therefore, guava leaf is considered safe for use as a water disinfectant in shrimp culture.

[Niche characteristics of common microalgae communities in prawn-aquaculture pond in terms of water temperature, salinity, nitrogen, and phosphorus resources].

A 4-factorial (water temperature, salinity, nitrogen, and phosphorus) experiment was designed to study the niche characteristics of four common microalgae communities in prawn-aquaculture pond. The results showed that the niche breadth was the greatest for Cryptomonas erosa in temperature and salinity resources (0.980 and 0.988, respectively) and for Niztzschia closterium in nitrogen and phosphorus resources (0.990), but the smallest for Chlorella pyrenoidosa in all test resources, with an average value of 0.926. As for niche overlap, it was the smallest for C. erosa and C. pyrenoidosa in temperature and salinity resources (0.809 and 0.702, respectively) and for C. erosa and N. closterium in nitrogen and phosphorus resources (0.829), but the greatest for C. pyrenoidosa and Nannichloropsis oculata in temperature, salinity, and nitrogen and phosphorus resources, with the values being 0.986, 0.974 and 0.989, respectively. All of these suggested that in prawn-aquaculture pond, C. erosa could be bred with any other three of the microalgae communities, while N. oculata and C. pyrenoidosa should not be bred together for their obvious competition

[Effects of antibiotics on bacterial community in shrimp hatchery system].

With bacterial 16S rRNA gene (rDNA) as molecular marker and by using PCR-DGGE technique, the fingerprints of bacterial community were constructed to study the effects of applying streptomycin sulfate, terramycin, and penicillin on the bacterial community in shrimp hatchery system. Within the 120 h experimental period, significant difference in the diversity of the bacterial community was observed between the treatments applied with 0.5 mg x L(-1) of test antibiotics and the control. In the control, the band patterns in 0-30 h were clustered into one clade, and those in 56-120 h were clustered into another; while in the treatments applied with test antibiotics, the band patterns in 0-56 h were clustered into one clade, and those in 72-120 h were clustered into another. After the sequencing of DGGE bands, the BLAST-N searches for sequence similarity showed great diversity of bacterial species, including culturable bacteria (mainly Sulfitobacter sp., Rhodobacteraceae sp., Photobacterium damselae, Synechoccoccus sp., Actinomycetales, Flavobacteriaceae, Filamentous photosynthetic, Mucus, and Vibrio harveyi) and some uncultured marine bacteria, among which, Rhodobacteraceae sp., Photobacterium damselae, Actinomycetales, Flavobacteriaceae, Mucus, and two unculturable bacteria were less affected by the three antibiotics, while Sulfitobacter sp., Filamentous photosynthetic, and other eight unculturable marine bacteria changed in different spatiotemporal patterns with the kinds of test antibiotics.