Tolerance to aerial exposure influences distributional patterns in multi-species intertidal seagrass meadows.

Multi-specific seagrass meadow assemblages dominate most tropical intertidal regions but the relative role of environmental stress in determining distribution patterns is still uncertain. Here we combine observational and experimental approaches to examine aerial exposure as a factor driving species occurrence patterns in intertidal meadows of the Andaman archipelago, where up to 6 seagrass species co-occur. In the studied meadow, patterns of exposure did not map onto distance from the coast, instead creating a patchy matrix of exposure, based on fine-scale bathymetric differences. Distributional surveys showed that seagrass species were similarly patchy, often tracking the degree of aerial exposure during low tide. While some species (Halophila ovalis, Halophila minor, and Thalassia hemprichii) frequently occurred in submerged or subtidal areas and were rarely found in completely exposed areas, other species (Cymodocea rotundata, Halophila beccarii, and Halodule uninervis) also occupied areas that were subject to partial or complete aerial exposure during low tide. To confirm this pattern, we used field-based transplant experiments, employing a natural gradient of tidal exposure to subject six seagrass species to different desiccation exposure times. After a month, H. beccarii and H. uninervis transplants survived in areas that sustained more than 3 h of aerial tidal exposure without significant mortality, compared with other species (H. ovalis, H. minor, T. hemprichii, C. rotundata) that showed dramatic shoot mortality at the same exposure regimes. For all species, 4 h represented the upper limit of exposure, in both experimental and distributional studies. However, despite their wider tolerance of exposure to air, H. beccarii and H. uninervis did not dominate the entire meadow. This could be a result either of their poor tolerance to other environmental factors or their lower competitive abilities among other mechanisms. This suggests that in tropical multi-specific meadows, strong environmental filters could override clear intertidal zonation to create patchy matrices based on species tolerances.

Association of chronic periodontitis and type 2 diabetes mellitus with salivary Del-1 and IL-17 levels.

PURPOSE: Chronic periodontitis (CP) and Type 2 diabetes mellitus (T2DM) are chronic diseases affecting the humans and have interrelationship in their pathogenesis. Monitoring the progress with biomarker in these disease is important from treatment outcome point of view. We investigated the association of salivary developmental endothelial locus-1 (Del-1) and interleukin-17 (IL-17) levels in CP and T2DM. METHODS: Saliva was collected from 17 healthy and 68 patients (divided into 4 groups based on presence or absence of CP and T2DM). Periodontal parameters were recorded at the time of visit. Del-1 and IL-17 levels in unstimulated salivary samples were determined using enzyme-linked immunosorbent assay. RESULTS: Study found the lower levels of salivary Del-1 and higher levels of IL-17 in CP (2.23 ± 2.10 ng/mL, 56.54 ± 19.79 ng/mL), CCDM ((1.97 ± 1.36 ng/mL, 74.74 ± 17.79 ng/mL) and CUDM (1.02 ± 0.52 ng/mL, 63.84 ± 24.72 ng/mL) as compared to healthy individuals (6.54 ± 2.07; 24.47 ± 8.23 ng/mL) (p < 0.001). Del-1 and IL-17 levels were correlating with inflammatory state in CP and presence of T2DM aggravate the severity of disease in CP. An inverse correlation between salivary Del-1 & IL-17 levels was also seen. Furthermore, we also observed that the combination of T2DM and CP (CCDM and CUDM) increases the salivary IL-17 levels and decreases Del-1 levels. CONCLUSIONS: There is an upregulation of salivary IL-17 and downregulation of salivary Del-1 with increase in severity of periodontal disease as well as T2DM. Furthermore, the presence of T2DM in chronic periodontitis patients can aggravate the inflammation related periodontal destruction.

The Effect of Piezoelectric Ultrasonic Scaler Tip Wear on Root Surface Roughness at Different Working Parameters: An Atomic Force Microscopic and Profilometric Study.

OBJECTIVE: This study aimed to evaluate the influence of scaler tip wear and different working parameters, i.e., lateral force, power setting and tip angulation, on the roughness of root surfaces following treatment with piezoelectric ultrasonic scaling devices. MATERIALS: Twenty piezoelectric ultrasonic scaler inserts (10 worn/10 new) were selected to examine the erosion ratio (ER) under atomic force microscopy (AFM). A total of 160 root samples were prepared and instrumented by new (n = 80) and worn inserts (n = 80) at different working parameters (tip angulation, power setting, lateral force). Roughness change (Rc) on root surfaces after instrumentation was examined by a contact profilometer. RESULTS: Statistically significant differences were found between the mean ERs of new and worn tips (p < 0.0001). The various combinations of the assessed working parameters showed synergistic effects resulting in a wide range of root surface roughness. The present study found the higher Rc in the group with a 45° angulation, (P10) high power setting and 1.0 N lateral force (subgroup 8) when compared to other groups. Among the groups, the worn scaler tips subgroup 8 showed a higher Rc (5.692 ± 0.81) when compared to new scaler tips subgroup 8 (4.798 ± 0.51; p < 0.001). CONCLUSION: The findings of the present study highlighted that scaler tip wear strongly influences the root surface roughness when used at higher tip angulation, lateral force and power settings. Hence, ultrasonic scaler tip wear should be periodically evaluated and should be considered as much as the other working parameters.