Water Soluble Pigments Containing Xylose and Glucose in Gametangia of the Green Alga, Bryopsis maxima

Several water-soluble pigments were purified from gametangiaof Bryopsis maxima by liquid chromatography and characterizedby pyridylamination and high-performance anion-exchange chromatography.The structure of the main red pigment is proposed based on thedata of infrared spectrum, Mass spectrum, ¹H and ¹³C NMR spectraand pyridylamino analysis. As a consequence, this pigment containeda tetrapyrrole with phytol and a sugar chain comprised of xyloseand glucose. The sequence of the sugars in the chain was determinedbased on its Mass spectrum. The pigment was similar to chlorophyll-originpigments observed in other plants. No aldehyde group, however,was present at C5 in the open tetrapyrrole chain. (Received August 3, 1994; Accepted November 10, 1994)     

Compound K, a metabolite of ginsenosides, induces cardiac protection mediated nitric oxide via Akt/PI3K pathway

AimsCompound K (C-K; 20-O-d-glucopyranosyl-20(S)-protopanaxadiol) is a novel ginsenoside metabolite formed by intestinal bacteria and does not occur naturally in ginseng. In this study, we investigated whether administration of C-K has protective effects on myocardial ischemia-reperfusion injury and its potential mechanisms.Main methodsWe used in vivo mouse models of ischemia-reperfusion injury and performed biochemical assays in excised hearts.Key findingsC-K reduced infarct size compared with the control group after ischemia-reperfusion. Immunoblot analysis showed that C-K significantly enhanced protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS) activity. Wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor, blocked cardiac protection in vivo and attenuated phosphorylation of Akt and eNOS. Additionally, the hearts of C-K pretreated mice showed inhibition of mitochondrial swelling induced by Ca²⁺.SignificanceThis study showed that Compound K pretreatment has protective effects on myocardial ischemia-reperfusion injury, partly by mediating the activation of PI3K pathway and phosphorylation of Akt and eNOS.     

The amino-terminal half of Sendai virus C protein is not responsible for either counteracting the antiviral action of interferons or down-regulating viral RNA synthesis

The Sendai virus C proteins, C', C, Y1, and Y2, are a nested set of independently initiated carboxy-coterminal proteins translated from a reading frame overlapping the P frame on the P mRNA. The C proteins are extremely versatile and have been shown to counteract the antiviral action of interferons (IFNs), to down-regulate viral RNA synthesis, and to promote virus assembly. Using the stable cell lines expressing the C, Y1, Y2, or truncated C protein, we investigated the region responsible for anti-IFN action and for down-regulating viral RNA synthesis. Truncation from the amino terminus to the middle of the C protein maintained the inhibition of the signal transduction of IFNs, the formation of IFN-stimulated gene factor 3 (ISGF3) complex, the generation of the anti-vesicular stomatitis virus state, and the synthesis of viral RNA, but further truncation resulted in the simultaneous loss of all of these inhibitory activities. A relatively small truncation from the carboxy terminus also abolished all of these inhibitory activities. These data indicated that the activities of the C protein to counteract the antiviral action of IFNs and to down-regulate viral RNA synthesis were not encoded within a region of at least 98 amino acids in its amino-terminal half.     

Nalidixic acid-resistant mutations of the gyrB gene of Escherichia coli

Summary DNA fragments of 3.4 kb containing the gyrB gene were cloned from Escherichia coli KL-16 and from spontaneous nalidixic acid-resistant mutants. The mutations (nal-24 and nal-31) had been determined to be in the gyrB gene by transduction analysis. Nucleotide sequence analysis of the cloned DNA fragments revealed that nal-24 was a G to A transition at the first base of the 426th codon of the gyrB gene, resulting in an amino acid change from aspartic acid to asparagine, and nal-31 was an A to G transition at the first base of the 447th codon, resulting in an amino acid change from lysine to glutamic acid. This indicates that mutations in the gyrB gene are responsible for nalidixic acid resistance.     

Human group III phospholipase A2 suppresses adenovirus infection into host cells. Evidence that group III, V and X phospholipase A2s act on distinct cellular phospholipid molecular species

Of 10 mammalian secreted phospholipase A(2) (sPLA(2)) enzymes identified to date, group V and X sPLA(2)s, which are two potent plasma membrane-acting sPLA(2)s, are capable of preventing host cells from being infected with adenovirus, and this anti-viral action depends on the conversion of phosphatidylcholine (PC) to lysophosphatidylcholine (LPC) in the host cell membrane. Here, we show that human group III sPLA(2), which is structurally more similar to bee venom PLA(2) than to other mammalian sPLA(2)s, also has the capacity to inhibit adenovirus infection into host cells. Mass spectrometry (MS) demonstrated that group III sPLA(2) hydrolyzes particular molecular species of PC to generate LPC in human bronchial epithelial cells. Remarkably, in addition to the catalytically active sPLA(2) domain, the N-terminal, but not C-terminal, domain unique to this enzyme was required for the anti-adenovirus effect. To our knowledge, this is the first demonstration that the biological action of group III sPLA(2) depends on its N-terminal domain. Finally, our MS analysis provided additional and novel evidence that group III, V and X sPLA(2)s target distinct phospholipid molecular species in cellular membranes.     

Sugar microanalysis by HPLC with benzoylation: improvement via introduction of a C-8 cartridge and a high efficiency ODS column

An HPLC protocol for sugar microanalysis based on the formation of ultraviolet-absorbing benzoyl chloride derivatives was improved. Here, samples were prepared with a C-8 cartridge and analyzed with a high efficiency ODS column, in which porous spherical silica particles 3 microm in diameter were packed. These devices allowed us to simultaneously quantify multiple sugars and sugar alcohols up to 10 ng/ml and to provide satisfactory separations of some sugars, such as fructose and myo-inositol and sorbitol and mannitol. This protocol, which does not require special apparatuses, should become a powerful tool in sugar research.     

Participation of proteasome-associating complex PC500 in starfish oocyte maturation as revealed by monoclonal antibodies

We previously reported that immature starfish oocytes contain a novel 530-kDa proteasome-associating complex PC500 [previously named PC530; E. Tanaka, M. Takagi Sawada, C. Morinaga, H. Yokosawa, H. Sawada, Isolation and characterization of a novel 530-kDa protein complex (PC 530) capable of associating with the 20S proteasome from star fish oocytes, Arch. Biochem. Biophys. 374 (2000) 181-188]. In the present study, in order to obtain an insight into the biological function of this complex, we investigated the effects of anti-PC500 monoclonal antibodies on oocyte maturation of the starfish Asterina pectinifera. A monoclonal antibody 7C5 strongly inhibited germinal vesicle breakdown (GVBD) in a concentration-dependent manner. In contrast to the inhibitory effect of the 7C5 antibody on GVBD, no inhibition of egg cleavage was observed in a 7C5-antibody-microinjected single blastomere in a 2-cell stage embryo. These results indicate that PC500 plays a key role in starfish oocyte maturation in a meiosis-specific manner.     

Mesenchymal stem cells cultured under hypoxia escape from senescence via down-regulation of p16 and extracellular signal regulated kinase

Hypoxia has been considered to affect the properties of tissue stem cells including mesenchymal stem cells (MSCs). Effects of long periods of exposure to hypoxia on human MSCs, however, have not been clearly demonstrated. MSCs cultured under normoxic conditions (20% pO₂) ceased to proliferate after 15-25 population doublings, while MSCs cultured under hypoxic conditions (1% pO₂) retained the ability to proliferate with an additional 8-20 population doublings. Most of the MSCs cultured under normoxic conditions were in a senescent state after 100 days, while few senescent cells were found in the hypoxic culture, which was associated with a down-regulation of p16 gene expression. MSCs cultured for 100 days under hypoxic conditions were superior to those cultured under normoxic conditions in the ability to differentiate into the chondro- and adipogenic, but not osteogenic, lineage. Among the molecules related to mitogen-activated protein kinase (MAPK) signaling pathways, extracellular signal regulated kinase (ERK) was significantly down-regulated by hypoxia, which helped to inhibit the up-regulation of p16 gene expression. Therefore, the hypoxic culture retained MSCs in an undifferentiated and senescence-free state through the down-regulation of p16 and ERK.