Larvae of the South Atlantic coral Favia gravida are tolerant to salinity and nutrient concentrations associated with river discharges.

Rivers release freshwater, nutrients and pollutants into reefs. This type of environmental stress reduces coral larvae settlement and alter its energy metabolism. We investigated the tolerance of Favia gravida (Scleractinia) larvae to river discharges. We exposed larvae to (i) different salinities (25, 30, 35 and 40 PSU); and (ii) dilutions of river water containing nutrients and metals (0, 20, 40, 60, 80 and 100% river water) under control salinity of 35 PSU. We then examined settlement and larval enzymatic activity. No differences in settlement were detected among salinities. Settlement was also similar to control for larvae under 100% river water. Enzymatic activity for citrate synthase remained unaltered for all treatments. Lactate dehydrogenase activity was slightly altered under different salinities, suggesting a mild stress response. Findings suggest that F. gravida larvae are tolerant to a wide range of salinity and nutrient conditions and that this is a stress-tolerant species.

Genetic polymorphism of MUC7 in individuals with aggressive or chronic periodontitis.

Individuals with periodontitis exhibit differential expression of mucin-glycoprotein-2 (MG2), a protein encoded by the MUC7 gene. It is well known that MG2 exerts bactericidal activity as well as exhibiting genetic polymorphism involving a variable number of tandem repeats (VNTR). In the present study, we assessed the distribution of allelic variants of the MUC7 gene in 22 individuals with aggressive periodonitis, 68 with chronic periodonitis, and 87 without periodonitis. Oral mucosal cells were collected, the DNA was extracted, and specific primers were used to amplify the region encoding the MUC7 tandem repeats (TRs). Polymerase chain reaction products were subjected to electrophoresis and analyzed on polyacrylamide gels stained with silver nitrate. Although the percentage distribution of homozygosity (6-6TR) and heterozygosity (5-6TR) showed variation among the groups, the observed differences were not statistically significant (P > 0.05; Fisher's Exact Test). The present results indicate that the expression of different numbers of TRs in this salivary mucin in the oral environment does not interfere with the etiopathogenesis of aggressive or chronic periodontitis.