Apoptosis in mouse taste buds after denervation

Apoptotic cells in the taste buds of mouse circumvallate papillae after the sectioning of bilateral glossopharyngeal nerves were examined by the method of DNA nick-end labeling (TUNEL), together with standard electron microscopy. The taste buds decreased in number and size 3–11 days after denervation and disappeared at 11 days. The TUNEL method revealed only a few positively stained nuclei in normal taste buds but, in those of mice 1–5 days after denervation, the number of positive nuclei had increased to 3–5 times that of taste buds from normal mice. Electron-microscopic observation after denervation demonstrated taste bud cells containing condensed and fragmentary nuclei in a cytoplasm with increased density. The results show that taste bud cells under normal conditions die by apoptosis at the end of their life span, and that gustatory nerve sectioning causes apoptosis of taste bud cells with taste buds decreasing in number and ultimately disappearing. Received: 20 November 1995 / Accepted: 15 May 1996     

A Gene-Specific Method for Predicting Hemophilia-Causing Point Mutations

A fundamental goal of medical genetics is the accurate prediction of genotype–phenotype correlations. As an approach to develop more accurate in silico tools for prediction of disease-causing mutations of structural proteins, we present a gene- and disease-specific prediction tool based on a large systematic analysis of missense mutations from hemophilia A (HA) patients. Our HA-specific prediction tool, HApredictor, showed disease prediction accuracy comparable to other publicly available prediction software. In contrast to those methods, its performance is not limited to non-synonymous mutations. Given the role of synonymous mutations in disease and drug codon optimization, we propose that utilizing a gene- and disease-specific method can be highly useful to make functional predictions possible even for synonymous mutations. Incorporating computational metrics at both nucleotide and amino acid levels along with multiple protein sequence/structure alignment significantly improved the predictive performance of our tool. HApredictor is freely available for download at http://www.ncbi.nlm.nih.gov/CBBresearch/Przytycka/HA_Predict/index.htm.     

Quantitative β-elimination-reduction of O-glycosyl linkages in chondroitin sulfates

The chondroitin 4-sulfate-peptide from whale cartilage contains serine, xylose, and galactose in ～1:1:2 molar ratio. Deamination with nitrous acid showed that about 50% of the serine is at the amino terminus. Various conditions of β-elimination-reduction were employed with the preparation to provide quantitative data on the linkage region between protein and carbohydrate. The optimal conditions used, 0.4m sodium hydroxide in the presence of 0.3m sodium borohydride and 0.01m PdCl₂·2H₂O for 24 h at 25°, resulted in an increase of alanine content and concomitant decrease of serine and conversion of xylose into xylitol, all in equimolar amounts. Furthermore, substitution of both the terminal amino and carboxyl groups, and elimination-reduction, brought about cleavage of most of the linkages; over 90% of the amino acids originally present were lost after re-isolation of the polymer fraction. These results indicate that β-elimination-reduction alone, under the optimal conditions, allows the mode of linkage to be quantitatively determined as an O-xylosylserine linkage. Under these optimal conditions, the linkage region between protein and a chondroitin 4- and 6-sulfate hybrid (1:1) from bovine tracheal cartilage was determined to be Gal-Gal-Xyl-O-Ser, thus being similar to that found in chondroitin 4-sulfate-peptide.     

Evidence for the location of OprM in the Pseudomonas aeruginosa outer membrane

Abstract OprM with a M _r of 49 K is associated with the multidrug resistance of Pseudomonas aeruginosa . Detergent fractionation of bacterial cells has demonstrated that OprM is located in the outer membrane from which it sediments with the other major outer membrane proteins. In this study we have determined the location of OprM as the P. aeruginosa outer membrane. Western immunoblots of cell fractions, obtained by sucrose density gradient centrifugation of whole cell lysates, were probed with an OprM-specific murine polyclonal antiserum.     

Effect of polynucleotides and a basic protein on the condensation of phenylalanyl adenylate

The effect of polyuridylate and of histone on the oligomerization of phenylalanyl adenylate was tested. Polyuridylate which pairs with adenine under suitable conditions showed no effect. Histone increased the rate of the polymerization whereas a neutral protein, albumin, had no effect. Simultaneous presence of nucleotides diminished the effect of histone. The implication of these results on the prebiotic polypeptide formation is discussed.     

Experimental Dental Caries on Gnotobiotic Inbred Mice

The purpose of this study in mono-infected gnotobiotic BALB/cA and C3H/HeN mice was to evaluate the cariogenicity of Enterococcus faecalis. The caries incidence and mean caries score in the BALB/cA mice were significantly higher than those in the C3H/HeN. In both of the mouse strains, the mean number of E. faecalis isolated from the cecum content was almost the same, however, the mean number of E. faecalis from the maxilla of BALB/cA was significantly higher than that of C3H/HeN. These results indicate that C3H/HeN has some factors that prevent E. faecalis from attaching to the tooth surfaces.