The effect of daily ingestion of collagen peptide on the skin damage induced by repeated UV-B irradiation was examined. Ingestion of collagen peptide (0.2 g/kg/d) suppressed UV-B-induced decreases in skin hydration, hyperplasia of the epidermis, and decreases in soluble type I collagen. These results suggest that collagen peptide is beneficial as a dietary supplement to suppress UV-B-induced skin damage and photoaging.

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Water stress is one of the major stresses experienced by cellular systems and can take a number of distinct forms. In response to turgor-related osmotic stress, cells produce compatible solutes that are macromolecule protectants and also counteract the outflow of water from stressed cells. In this report we show that the germination of conidia of Aspergillus nidulans, a sensitive indicator of water stress, in the presence of ethanol is correlated with the intracellular concentration of the compatible solutes glycerol and erythritol, which protect against both osmotic and nonturgor forms of water stress.Cellular systems consist of up to 97% water, so thermodynamic changes in water availability cause fundamental biological stress that can severely impact vital metabolic processes (3). Water stress can be induced by a net loss of water from cells, e.g., due to high levels of extracellular solutes such as NaCl that reduce cell turgor and induce osmotic stress. Cells exposed to such agents are subjected to both reduced turgor and stabilizing effects on macromolecules, which can lead to membrane rigidity and impairment of protein structure (3,16,19,25). Intracellular water activity also may be reduced by chaotropic compounds, such as ethanol, that decrease the strength of hydrogen bonding and other electrostatic interactions and thereby perturb the structure and function of hydrated macromolecules, including nucleic acids, proteins, and lipids.Cells generally respond to osmotic stress by acquiring and/or producing compatible solutes that protect macromolecule structure and at the same time increase the osmotic pressure of the cytoplasm and thereby counteract water loss from cells (1, 3). Our working hypothesis is that these compatible solutes also protect against intracellular water stress due to alterations in the hydration of cellular macromolecules caused by ethanol, a chaotropic solute that does not cause osmotic stress.The ascomycete Aspergillus (Emericella) nidulans is a model microorganism whose genetics and metabolism, including those related to stress and toxicology, have been widely studied. A. nidulans, like most yeast and fungal cells, synthesizes low-molecular-weight polyols, such as glycerol, in response to osmotic stress (3, 21). Our objective in this study was to determine whether increased intracellular levels of glycerol and erythritol affect conidial germination in A. nidulans when the organism is cultured under conditions that reduce cell turgor and induce osmotic stress (e.g., in a high-NaCl environment), as well as those that increase intracellular water stress by reducing the strength of water-macromolecule interactions (e.g., at high ethanol concentrations). MATERIALS AND METHODSOrganism, media, and production of conidia. A culture of A. nidulans (IFO 4342) was obtained from the Institute for Fermentation Osaka (Osaka, Japan) and maintained on potato dextrose agar (PDA; Nissui, Tokyo, Japan) at 25°C. All media were buffered with 21.3 g of 2-(N-morpholino)ethanesulfonic acid (MES) liter Ϫ1 , and...

The cell walls of filamentous fungi in the genus Aspergillus have galactofuranose-containing polysaccharides and glycoconjugates, including O-glycans, N-glycans, fungal-type galactomannan, and glycosylinositolphosphoceramide, which are important for cell wall integrity. Here, we attempted to identify galactofuranosyltransferases that couple galactofuranose monomers onto other wall components in Aspergillus nidulans. Using reverse-genetic and biochemical approaches, we identified that the AN8677 gene encoded a galactofuranosyltransferase, which we called GfsA, involved in galactofuranose (Galf) antigen biosynthesis. Disruption of gfsA reduced binding of β-Galf-specific antibody EB-A2 to O-glycosylated WscA protein and galactomannoproteins. The results of an in-vitro galactofuranose antigen synthase assay revealed that GfsA has β1,5- or β1,6- galactofuranosyltransferase activity for O-glycans in glycoproteins, uses UDP-D-galactofuranose as a sugar donor, and requires a divalent manganese cation for activity. GfsA was found to be localized at the Golgi apparatus based on cellular fractionation experiments. ΔgfsA cells exhibited an abnormal morphology characterized by poor hyphal extension, hyphal curvature, and limited formation of conidia. Several gfsA orthologs were identified in members of the Pezizomycotina subphylum of Ascomycota, including the human pathogen Aspergillus fumigatus. To our knowledge, this is the first characterization of a fungal β-galactofuranosyltransferase, which was shown to be involved in galactofuranose antigen biosynthesis of O-glycans in the Golgi.

In this study we report the cloning and characterization of a novel human aminopeptidase, which we designate leukocyte-derived arginine aminopeptidase (L-RAP). The sequence encodes a 960-amino acid protein with significant homology to placental leucine aminopeptidase and adipocyte-derived leucine aminopeptidase. The predicted L-RAP contains the HEXXH(X) 18 E zinc-binding motif, which is characteristic of the M1 family of zinc metallopeptidases. Phylogenetic analysis indicates that L-RAP forms a distinct subfamily with placental leucine aminopeptidase and adipocyte-derived leucine aminopeptidase in the M1 family. Immunocytochemical analysis indicates that L-RAP is located in the lumenal side of the endoplasmic reticulum. Among various synthetic substrates tested, L-RAP revealed a preference for arginine, establishing that the enzyme is a novel arginine aminopeptidase with restricted substrate specificity. In addition to natural hormones such as angiotensin III and kallidin, L-RAP cleaved various N-terminal extended precursors to major histocompatibility complex class I-presented antigenic peptides. Like other proteins involved in antigen presentation, L-RAP is induced by interferon-␥. These results indicate that L-RAP is a novel aminopeptidase that can trim the N-terminal extended precursors to antigenic peptides in the endoplasmic reticulum.