Characterization of Two Distinct Calcium-Binding Sites in the Amino-Terminus of Human Profilaggrin

Profilaggrin is a large phosphorylated protein (approximately 400 kDa In humans) that is expressed in the granular cells of epidermis where it forms a major component of keratohyalin. It consists of multiple copies of similar filaggrin units plus amino- and carboxy-terminal domains that differ from filaggrin. Proteolytic processing of profilaggrin during terminal differentiation results in the removal of these domains and generation of monomeric filaggrin units, which associate with keratin intermediate filaments to form macrofibrils in the stratum corneum. The amino-terminal domain contains two calcium-binding motifs similar to the EF-hands found in the S-100 family of calcium-binding proteins. In this report, we expressed the 293-residue amino-terminal pro-domain of human profilaggrin as a polyhistidine fusion protein in Escherichia coli, and characterized calcium binding by a 45Ca++ binding assay and fluorescence emission spectroscopy. fluorescence measurements indicated that the profilaggrin polypeptide undergoes conformational changes upon the removal of Ca++ with ethylenediamine tetraacetic acid, demonstrating the presence of two calcium-binding sites with affinities for calcium that differ ninefold (1.4 × 10-4 M and 1.2 × 10-3 M). We suggest that this functional calcium-binding domain at the amino-terminus of human profilaggrin plays a role in profilaggrin processing and in other calcium-dependent processes during terminal differentiation of the epidermis

The genome of Aeromonas salmonicida subsp. salmonicida A449: insights into the evolution of a fish pathogen

Background Aeromonas salmonicida subsp. salmonicida is a Gram-negative bacterium that is the causative agent of furunculosis, a bacterial septicaemia of salmonid fish. While other species of Aeromonas are opportunistic pathogens or are found in commensal or symbiotic relationships with animal hosts, A. salmonicida subsp. salmonicida causes disease in healthy fish. The genome sequence of A. salmonicida was determined to provide a better understanding of the virulence factors used by this pathogen to infect fish. Results The nucleotide sequences of the A. salmonicida subsp. salmonicida A449 chromosome and two large plasmids are characterized. The chromosome is 4,702,402 bp and encodes 4388 genes, while the two large plasmids are 166,749 and 155,098 bp with 178 and 164 genes, respectively. Notable features are a large inversion in the chromosome and, in one of the large plasmids, the presence of a Tn21 composite transposon containing mercury resistance genes and an In2 integron encoding genes for resistance to streptomycin/spectinomycin, quaternary ammonia compounds, sulphonamides and chloramphenicol. A large number of genes encoding potential virulence factors were identified; however, many appear to be pseudogenes since they contain insertion sequences, frameshifts or in-frame stop codons. A total of 170 pseudogenes and 88 insertion sequences (of ten different types) are found in the A. salmonicida genome. Comparison with the A. hydrophila ATCC 7966T genome reveals multiple large inversions in the chromosome as well as an approximately 9% difference in gene content indicating instances of single gene or operon loss or gain. A limited number of the pseudogenes found in A. salmonicida A449 were investigated in other Aeromonas strains and species. While nearly all the pseudogenes tested are present in A. salmonicida subsp. salmonicida strains, only about 25% were found in other A. salmonicida subspecies and none were detected in other Aeromonas species. Conclusion Relative to the A. hydrophila ATCC 7966T genome, the A. salmonicida subsp. salmonicida genome has acquired multiple mobile genetic elements, undergone substantial rearrangement and developed a significant number of pseudogenes. These changes appear to be a consequence of adaptation to a specific host, salmonid fish, and provide insights into the mechanisms used by the bacterium for infection and avoidance of host defence systems.Peer reviewed: YesNRC publication: Ye

Oral Antimicrobial Peptides and Biological Control of Caries

The presence of antimicrobial peptides (AMPs) in saliva may be a biological factor that contributes to susceptibility or resistance to caries. This manuscript will review AMPs in saliva, consider their antimicrobial and immunomodulatory functions, and evaluate their potential role in the oral cavity for protection of the tooth surface as well as the oral mucosa. These AMPs are made in salivary gland and duct cells and have broad antimicrobial activity. Alpha-defensins and LL37 are also released by neutrophils into the gingival crevicular fluid. Both sources may account for their presence in saliva. A recent study in middle school children aimed to determine a possible correlation between caries prevalence in children and salivary concentrations of the antimicrobial peptides human beta-defensin-3 (hBD-3), the cathelicidin, LL37, and the alpha-defensins. The levels of these AMPs were highly variable in the population. While levels of LL37 and hBD-3 did not correlate with caries experience, the mean alpha-defensin level was significantly higher in children with no caries than in children with caries (p < 0.005). We conclude that several types of AMPs that may have a role in oral health are present in unstimulated saliva. Low salivary levels of alpha-defensin may represent a biological factor that contributes to caries susceptibility. Our observation could lead to new ways to prevent caries and to a new tool for caries risk assessment

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

UI Dark Patterns and Where to Find Them A Study on Mobile Applications and User Perception

A Dark Pattern (DP) is an interface maliciously crafted to deceive users into performing actions they did not mean to do. In this work, we analyze Dark Patterns in 240 popular mobile apps and conduct an online experiment with 589 users on how they perceive Dark Patterns in such apps. The results of the analysis show that 95% of the analyzed apps contain one or more forms of Dark Patterns and, on average, popular applications include at least seven different types of deceiving interfaces. The online experiment shows that most users do not recognize Dark Patterns, but can perform better in recognizing malicious designs if informed on the issue. We discuss the impact of our work and what measures could be applied to alleviate the issue

Revolution and Peace

Alft:!~:I~~~tion on War