Improvement of bone strength and dermal thickness due to dietary edible bird's nest extract in ovariectomized rats

Oral administration of edible bird's nest extract (EBNE) improved bone strength and calcium concentration in the femur of ovariectomized rats. Dermal thickness was also increased by EBNE supplementation, whereas EBNE administration did not affect the serum estradiol concentration. These results suggest that EBNE is effective for the improvement of bone loss and skin aging in postmenopause all women.     

Regulation of lipid metabolism by palmitoleate and eicosapentaenoic acid (EPA) in mice fed a high-fat diet

We investigated whether oral administration of palmitoleate ameliorates disorders of lipid metabolism to clarify the effects of one of the components of fish oil. Lipid levels in the liver and plasma were significantly decreased by palmitoleate and by EPA administration. These results suggest that palmitoleate, in addition to EPA, plays a role in the regulation of lipid metabolism by fish oil.     

Two new subfamilies of DNA mismatch repair proteins (MutS) specifically abundant in the marine environment

MutS proteins are ubiquitous in cellular organisms and have important roles in DNA mismatch repair or recombination. In the virus world, the amoeba-infecting Mimivirus, as well as the recently sequenced Cafeteria roenbergensis virus are known to encode a MutS related to the homologs found in octocorals and ɛ-proteobacteria. To explore the presence of MutS proteins in other viral genomes, we performed a genomic survey of four giant viruses (‘giruses'') (Pyramimonas orientalis virus (PoV), Phaeocystis pouchetii virus (PpV), Chrysochromulina ericina virus (CeV) and Heterocapsa circularisquama DNA virus (HcDNAV)) that infect unicellular marine algae. Our analysis revealed the presence of a close homolog of Mimivirus MutS in all the analyzed giruses. These viral homologs possess a specific domain structure, including a C-terminal HNH-endonuclease domain, defining the new MutS7 subfamily. We confirmed the presence of conserved mismatch recognition residues in all members of the MutS7 subfamily, suggesting their role in DNA mismatch repair rather than DNA recombination. PoV and PpV were found to contain an additional type of MutS, which we propose to call MutS8. The MutS8 proteins in PoV and PpV were found to be closely related to homologs from ‘Candidatus Amoebophilus asiaticus'', an obligate intracellular amoeba-symbiont belonging to the Bacteroidetes. Furthermore, our analysis revealed that MutS7 and MutS8 are abundant in marine microbial metagenomes and that a vast majority of these environmental sequences are likely of girus origin. Giruses thus seem to represent a major source of the underexplored diversity of the MutS family in the microbial world.     

Mitochondrial DNA mutations regulate metastasis of human breast cancer cells

Mutations in mitochondrial DNA (mtDNA) might contribute to expression of the tumor phenotypes, such as metastatic potential, as well as to aging phenotypes and to clinical phenotypes of mitochondrial diseases by induction of mitochondrial respiration defects and the resultant overproduction of reactive oxygen species (ROS). To test whether mtDNA mutations mediate metastatic pathways in highly metastatic human tumor cells, we used human breast carcinoma MDA-MB-231 cells, which simultaneously expressed a highly metastatic potential, mitochondrial respiration defects, and ROS overproduction. Since mitochondrial respiratory function is controlled by both mtDNA and nuclear DNA, it is possible that nuclear DNA mutations contribute to the mitochondrial respiration defects and the highly metastatic potential found in MDA-MB-231 cells. To examine this possibility, we carried out mtDNA replacement of MDA-MB-231 cells by normal human mtDNA. For the complete mtDNA replacement, first we isolated mtDNA-less (ρ(0)) MDA-MB-231 cells, and then introduced normal human mtDNA into the ρ(0) MDA-MB-231 cells, and isolated trans-mitochondrial cells (cybrids) carrying nuclear DNA from MDA-MB-231 cells and mtDNA from a normal subject. The normal mtDNA transfer simultaneously induced restoration of mitochondrial respiratory function and suppression of the highly metastatic potential expressed in MDA-MB-231 cells, but did not suppress ROS overproduction. These observations suggest that mitochondrial respiration defects observed in MDA-MB-231 cells are caused by mutations in mtDNA but not in nuclear DNA, and are responsible for expression of the high metastatic potential without using ROS-mediated pathways. Thus, human tumor cells possess an mtDNA-mediated metastatic pathway that is required for expression of the highly metastatic potential in the absence of ROS production.     

Cyanidioschyzon merolae genome. A tool for facilitating comparable studies on organelle biogenesis in photosynthetic eukaryotes

The ultrasmall unicellular red alga Cyanidioschyzon merolae lives in the extreme environment of acidic hot springs and is thought to retain primitive features of cellular and genome organization. We determined the 16.5-Mb nuclear genome sequence of C. merolae 10D as the first complete algal genome. BLASTs and annotation results showed that C. merolae has a mixed gene repertoire of plants and animals, also implying a relationship with prokaryotes, although its photosynthetic components were comparable to other phototrophs. The unicellular green alga Chlamydomonas reinhardtii has been used as a model system for molecular biology research on, for example, photosynthesis, motility, and sexual reproduction. Though both algae are unicellular, the genome size, number of organelles, and surface structures are remarkably different. Here, we report the characteristics of double membrane- and single membrane-bound organelles and their related genes in C. merolae and conduct comparative analyses of predicted protein sequences encoded by the genomes of C. merolae and C. reinhardtii. We examine the predicted proteins of both algae by reciprocal BLASTP analysis, KOG assignment, and gene annotation. The results suggest that most core biological functions are carried out by orthologous proteins that occur in comparable numbers. Although the fundamental gene organizations resembled each other, the genes for organization of chromatin, cytoskeletal components, and flagellar movement remarkably increased in C. reinhardtii. Molecular phylogenetic analyses suggested that the tubulin is close to plant tubulin rather than that of animals and fungi. These results reflect the increase in genome size, the acquisition of complicated cellular structures, and kinematic devices in C. reinhardtii.     

Protective effect of egg yolk phosvitin against ultraviolet-light-induced lipid peroxidation in the presence of iron ions

It is known that nonheme iron accumulates and free radicals are generated in skin exposed to ultraviolet (UV) light. Iron ions have a role in skin photodamage by participating in the formation of reactive oxygen species. In this study, we evaluated the effect of egg yolk phosvitin on UV-light-induced oxidative stress. Mouse dorsal skin homogenate was exposed to UVA light in the presence or absence of ferric nitrilotriacetate, (FeNTA). Lipid peroxidation was determined by measuring thiobarbituric acid-reactive substances (TBARS). The TBARS concentration increased with increasing FeNTA concentration and UV-light-exposure time. In the presence of FeNTA, phosvitin more effectively inhibited in vitro lipid peroxidation than did bovine serum albumin. According to results of electron spin resonance studies using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trapping agent, phosvitin suppressed the formation of hydroxyl radicals. These results suggest that UV-light-induced oxidative stress can be reduced by phosvitin.     

Roles of C-terminal processing, and involvement in transacylation reaction of human group IVC phospholipase A2 (cPLA2gamma)

The phospholipase A2s (PLA2s) are a diverse group of enzymes that hydrolyze the sn-2 fatty acid from phospholipids and play a role in a wide range of physiological functions. A 61-kDa calcium-independent PLA2, termed cPLA2gamma, was identified as an ortholog of cPLA2alpha with approximately 30% overall sequence identity. cPLA2gamma contains a potential prenylation motif at its C terminus, and is known to have PLA2 and lysophospholipase activities, but its physiological roles have not been clarified. In the present study, we expressed various forms of recombinant cPLA2gamma, including non-prenylated and non-cleaved forms, in order to investigate the effects of C-terminal processing. We examined the expression of the wild type and non-prenylated (SCLA) forms of cPLA2gamma, and found that the SCLA form was expressed normally and retained almost full activity. Expression of the prenylated and non-cleaved form of cPLA2gamma using yeast mutants lacking prenyl protein proteases AFC1 (a-factor-converting enzyme) and RCE1 (Ras-converting enzyme) revealed decreased expression in the mutant strain compared to that in the wild type yeast, suggesting that complete C-terminal processing is important for the functional expression of cPLA2gamma. In addition, cPLA2gamma was found to have coenzyme A (CoA)-independent transacylation and lysophospholipid (LPL) dismutase (LPLase/transacylase) activities, suggesting that it may be involved in fatty acid remodeling of phospholipids and the clearance of toxic lysophospholipids in cells.     

Red blood cells highly express type I platelet-activating factor-acetylhydrolase (PAF-AH) which consists of the alpha1/alpha2 complex

Although red blood cells account for about 30% of total PAF-AH activity found in the blood, the physiological function of this enzyme is unknown. To understand the role and regulatory mechanism of this enzyme, we purified it from easily obtainable pig red blood cells. PAF-AH activity was mainly found in the soluble fraction of the red blood cells. Two peaks of enzyme activity appeared with increasing concentration of imidazole on column chromatography on nickel-nitroacetic acid (Ni-NTA) resin. We called these peaks of small and large enzyme activities fractions X and Y, respectively, and then further purified the enzymes by sequential chromatofocusing on Mono P and gel filtration on TSK G-3000. In the final preparation from fraction Y, two proteins bands corresponding to 26 kDa and 28 kDa were related to enzyme activity. Determination of the partial amino acid sequences of the proteins of 26 kDa and 28 kDa revealed that these proteins were identical to alpha(1) and alpha(2), respectively, both of which are catalytic subunits of Type I intracellular PAF-AH. On Western analysis, the 26 kDa and 28 kDa protein bands cross-reacted with specific monoclonal antibodies to alpha(1) and alpha(2), respectively. Since the apparent molecular weight of the natural enzyme was estimated to be about 60 kDa, the enzyme activity in fraction Y was thought to be that of a heterodimer consisting of alpha(1) and alpha(2). On the other hand, the enzyme activity in fraction X was thought to be that of a homodimer consisting of alpha(2). Other blood cells such as polymorphonuclear leukocytes and platelets only contained the alpha(2)/alpha(2) homodimer. It has been reported that the alpha(1)/alpha(2) heterodimer is poorly expressed in adult animals except for in the spermatogonium. Taken altogether, these results suggest that high expression of the alpha(1)/alpha(2) heterodimer is important for the physiological function of mature red blood cells.