Reduction of saliva-promoted adhesion of Streptococcus mutans MT8148 and dental biofilm development by tragacanth gum and yeast-derived phosphomannan

Proteome analysis of high affinity mouse saliva proteins to hydroxyapatite

Caries sensitivity varies between the two strains of inbred mice, BALB/cA has high sensitivity and C3H/HeN has low sensitivity. One potential reason seems to be a difference in pellicle-forming saliva protein composition. Here, we performed a proteomic analysis in order to identify differences of hydroxyapatite (HAP) adsorbed saliva proteins between these two mouse strains. HAP column chromatography revealed twice the quantity of high-affinity saliva proteins in C3H/HeN compared to BALB/cA. One- and two-dimensional electrophoresis showed 2 bands/spots with deviating migration. They were identified as murine carbonic anhydrase VI (CAVI) by peptide mass fingerprinting and confirmed with western blotting using a specific polyclonal antibody. Total RNA from the salivary glands of both mouse strains, PCR amplification of cDNA with a CAVI specific primer, and sequence analysis revealed one different base in codon 96, resulting in one different amino acid. Glyco-chains of CAVI deviate in one N-glycan, confirmed by mass analysis. CAVI activity was estimated from distinct circular dichroism spectra of the molecules and found higher in C3H/HeN mice. In summary, the CAVI composition of BALB/cA and C3H/HeN differs in one amino acid and a glyco-chain modification. Further, saliva from caries resistant C3H/HeN mice displayed higher CAVI activity and also overall hydroxyapatite adsorption, suggesting a relationship with caries susceptibility.

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CAVI was the salivary protein with high affinity for hydroxyapatite in two mice strains with different caries susceptibility.

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CAVI of the two strains showed differences in molecular weight, amino acids and genes, glyco-chain modification and enzyme activity.

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Differences in CAVI activity might contribute to caries susceptibility.

A biological active artificial saliva formulation containing flower mucilage from Ceylon Spinach (Basella alba Linn.)

Ceylon Spinach (Basella albe) is an edible perennial vine found in tropical Asia and Africa, known as vegetables containing mucilage. Its mucilage from flowers was extracted by microwaving and precipitated with 95% ethanol. Five artificial saliva formulations composing of mucilage from Ceylon Spinach, calcium chloride (CaCl₂), potassium chloride (KCl) and sodium fluoride (NF) were developed. The best formulation No.5 containing 0.61% of the mucilage with the non-Newtonian pseudoplastic flow (8.9 ± 0.2 cP) and the wetting time (12.50 ± 2.24 min) similar to the normal human saliva was selected. This artificial saliva formulation exhibited biological activities including an antioxidative activity by DPPH free radical scavenging with the SC₅₀ of 14.26 ± 2.00 mg/ml (0.05 folds of ascorbic acid), and the adhesion inhibition of S. mutans on hydroxyapatite beads at 17.01 ± 7.75%, while the natural human saliva exhibited an increase bacterial adhesion of 33.10 ± 9.70%. The safety of this formulation which gave no cytotoxicity on normal human gingival fibroblasts at 99.20 ± 21.09% cell viability was also demonstrated. The results from this study have indicated high biological activity and safety of the developed formulation containing mucilage from Ceylon Spinach which is potential to be used as artificial saliva for xerostomia patients.

Mannan and phosphomannan from Kuraishia capsulata yeast

Linear mannan and branched phosphomannan were identified as exopolysaccharides produced by Kuraishia capsulata yeast. Their structures were determined using nuclear magnetic resonance spectroscopy. The repeating unit of mannan was found to be a trisaccharide →6)-α-Manp-(1→2)-α-Manp-(1→2)-α-Manp-(1→, while the phosphomannan was shown to be built of β-Manp-(1→2)-α-Manp-(1 disaccharide blocks linked by phosphodiester bonds via C-1 and C-6 of the reducing unit. The production of both polysaccharides was shown to depend on the phosphate concentration in the culture medium. In the absence of phosphate, only mannan was obtained, while an excess of KH₂PO₄ led to the exclusive production of phosphomannan. Chemical depolymerisation of phosphomannan led to the formation of disaccharide β-Manp-(1→2)-(6-P)-Manp, representing the repeating unit of the hydrolysed polysaccharide. The treatment of the disaccharide with alkaline phosphatase resulted in the formation of disaccharide β-Manp-(1→2)-Manp. The latest products can be transformed into glycosyl donors applicable further in the synthesis of oligosaccharides related to Candida cell wall polysaccharides.

Salivary proteins and microbiota as biomarkers for early childhood caries risk assessment

Early childhood caries (ECC) is a term used to describe dental caries in children aged 6 years or younger. Oral streptococci, such as Streptococcus mutans and Streptococcus sorbrinus, are considered to be the main etiological agents of tooth decay in children. Other bacteria, such as Prevotella spp. and Lactobacillus spp., and fungus, that is, Candida albicans, are related to the development and progression of ECC. Biomolecules in saliva, mainly proteins, affect the survival of oral microorganisms by multiple innate defensive mechanisms, thus modulating the oral microflora. Therefore, the protein composition of saliva can be a sensitive indicator for dental health. Resistance or susceptibility to caries may be significantly correlated with alterations in salivary protein components. Some oral microorganisms and saliva proteins may serve as useful biomarkers in predicting the risk and prognosis of caries. Current research has generated abundant information that contributes to a better understanding of the roles of microorganisms and salivary proteins in ECC occurrence and prevention. This review summarizes the microorganisms that cause caries and tooth-protective salivary proteins with their potential as functional biomarkers for ECC risk assessment. The identification of biomarkers for children at high risk of ECC is not only critical for early diagnosis but also important for preventing and treating the disease.

Complete DNA sequence of Kuraishia capsulata illustrates novel genomic features among budding yeasts (Saccharomycotina)

The numerous yeast genome sequences presently available provide a rich source of information for functional as well as evolutionary genomics but unequally cover the large phylogenetic diversity of extant yeasts. We present here the complete sequence of the nuclear genome of the haploid-type strain of Kuraishia capsulata (CBS1993^T), a nitrate-assimilating Saccharomycetales of uncertain taxonomy, isolated from tunnels of insect larvae underneath coniferous barks and characterized by its copious production of extracellular polysaccharides. The sequence is composed of seven scaffolds, one per chromosome, totaling 11.4 Mb and containing 6,029 protein-coding genes, ∼13.5% of which being interrupted by introns. This GC-rich yeast genome (45.7%) appears phylogenetically related with the few other nitrate-assimilating yeasts sequenced so far, Ogataea polymorpha, O. parapolymorpha, and Dekkera bruxellensis, with which it shares a very reduced number of tRNA genes, a novel tRNA sparing strategy, and a common nitrate assimilation cluster, three specific features to this group of yeasts. Centromeres were recognized in GC-poor troughs of each scaffold. The strain bears MAT alpha genes at a single MAT locus and presents a significant degree of conservation with Saccharomyces cerevisiae genes, suggesting that it can perform sexual cycles in nature, although genes involved in meiosis were not all recognized. The complete absence of conservation of synteny between K. capsulata and any other yeast genome described so far, including the three other nitrate-assimilating species, validates the interest of this species for long-range evolutionary genomic studies among Saccharomycotina yeasts.