Effect of shading imposed by the algae Chaeotomorpha linum loads on structure, morphology and physiology of the seagrass Cymodocea nodosa.

In shallow coastal waters, seagrass and macroalgae occur together but under eutrophic conditions, bloom-forming algae can take over seagrasses causing an irreversible regime shift. Understanding the effect of macroalgae loads on seagrass meadows at an early stage can help prevent the loss of these ecosystems and the services they provide. In the present study, in situ experiments were conducted for 90 days in Bekalta (eastern coast of Tunisia) to assess the response of the seagrass Cymodocea nodosa when challenged with shading induced by filamentous macroalgae Chaetomorpha linum. Structural, morphological and physiological variables were regularly measured during the experiment. Shaded plants showed a sharp decline in shoot density, growth rate, and above-ground biomass, the impact being more pronounced on the physiological traits. Besides, shading by C. linum induced a significant increase in the contents of leaf photosynthetic pigments and phenolic compounds, whereas causing a decrease in soluble protein and sugar concentrations. Thus, shading imposed by C. linum loads appeared to induce a phoadpatative response in C. nodosa concomitant with carbon mobilization.

Effect of ozone to remineralize initial enamel caries: in situ study.

OBJECTIVES: Effect of ozonated water in remineralizing artificially created initial enamel caries was investigated using laser fluorescence and polarized light microscopy in an in situ study. MATERIALS AND METHODS: Teeth specimens (buccal sections) were immersed in 5-ml solution of 2 mM CaCl2, 2 mM NaH2P04, and 50 mM CH3COOH at pH of 4.55 for 5 h in an incubator at 37° to create subsurface demineralization. After which, they were randomly allocated into one of the following remineralization regimens: ozone (ozonated water 0.1 mg/l and 10 % nano-hydroxyapatite paste, Aclaim(TM)), without ozone (only 10 % nano-hydroxyapatite paste, Aclaim(TM)), and control (subjects' saliva alone). Specimens were embedded in acrylic retainers worn by orthodontic patients throughout the 21-day study duration and constantly exposed to their saliva. Laser fluorescence was recorded for all the specimens at baseline, after demineralization, and remineralization using DIAGNOdent, and the results were validated using polarized microscopic examination. The results were analyzed using repeated measures, one-way ANOVA with post hoc multiple comparisons. RESULTS: Reduced DIAGNOdent scores and greater depth of remineralization following application of ozonated water and nano-hydroxyapatite were found compared to those of the without ozone and control groups (P < 0.001), and the ozone-treated group exhibited maximum remineralization under the polarized light microscopy. CONCLUSION: Ozonated water can be considered an effective agent in reversing the initial enamel caries alongside with nano-hydroxyapatite compared to nano-hydroxyapatite alone and saliva. CLINICAL RELEVANCE: Ozone water can be used to remineralize incipient carious lesions, and it enhances the remineralizing potential of nano-hydroxyapatite thereby preventing the tooth from entering into the repetitive restorative cycle.