Stimulation of the secretion of pro-inflammatory cytokines by Bifidobacterium strains

To characterize the ability of bifidobacteria to affect the production of macrophage-derived cytokines, a murine macrophage-like cell line, J774.1, was cultured in the presence of 27 strains of heat-inactivated bifidobacteria. Bifidobacterium adolescentis and B. longum, known as adult-type bifidobacteria, induced significantly more pro-inflammatory cytokine secretion, IL-12 and TNF-alpha, by J774.1 cells, than did the infant-type bifidobacteria, B. bifidum, B. breve, and B. infantis (P<0.01). In contrast, B. adolescentis did not stimulate the production of anti-inflammatory IL-10 from J774.1 cells as the other tested bacteria did. The results suggest that the adult-type bifidobacteria, especially B. adolescentis, may be more potent to amplify but less able to down-regulate the inflammatory response.     

Stochasticity of the step size in the force generating process due to a single myosin molecule

We formulate a motional model on the basis of an experimental optical trapping system which reveals the single molecular events of the force generation due to actin and myosin, and we discuss the origin of the dispersion of the displacements of the beads bound to the actin filament. In some experimental data sets, this dispersion is larger than that presumed from the model under the condition that the thermal agitation is the only source of the fluctuation. Thus, other fluctuating elements besides that due to thermal agitation are supposed to cause the dispersion. A possible fluctuating element is the step size itself. We discuss this possibility and estimate the fluctuation in step size using two reported experimental data sets.     

Chondroitin sulfate disrupts axon pathfinding in the optic tract and alters growth cone dynamics

Little is known about the cues that guide retinal axons across the diencephalon en route to their midbrain target, the optic tectum. Here we show that chondroitin sulfate proteoglycans are differentially expressed within the diencephalon at a time when retinal axons are growing within the optic tract. Using exposed brain preparations, we show that the addition of exogenous chondroitin sulfate results in retinal pathfinding errors. Retinal axons disperse widely from their normal trajectory within the optic tract and extend aberrantly into inappropriate regions of the forebrain. Time-lapse analysis of retinal growth cone dynamics in vivo shows that addition of exogenous chondroitin sulfate causes intermittent stalling and increases growth cone complexity. These results suggest that chondroitin sulfate may modulate the guidance of retinal axons as they grow through the diencephalon towards the optic tectum.     

Arginine residue at position 573 in Enterococcus hirae vacuolar-type ATPase NtpI subunit plays a crucial role in Na+ translocation

The 76-kDa NtpI subunit constitutes the membrane-embedded V(0) moiety of Enterococcus hirae vacuolar type Na+-ATPase with a 16-kDa NtpK hexamer containing Na+ binding sites. In this study, we investigated the role of an arginine residue, which is highly conserved among the corresponding subunits of bacterial vacuolar-type ATPases, at position 573 of NtpI. Substitution of Glu, Leu, or Gln for Arg-573 abolished sodium transport and sodium-stimulated ATP hydrolysis of the enzyme. The conservative replacement of Arg by Lys lowered both activities about one-fifth of those of the wild type enzyme. We have reported previously on ATP-dependent negative cooperativity for Na+ coupling of this enzyme (Murata, T., Kakinuma, Y., and Yamato, I. (2001) J. Biol. Chem. 276, 48337-48340). The negative cooperativity for the Na+ dependence of ATPase activity was weakened by the mutation R573K; the Hill coefficients for the wild type and mutant enzymes at a saturated ATP concentration were 0.22 +/- 0.03 and 0.40 +/- 0.05, respectively. The Hill coefficients of both enzymes at limited ATP concentrations approached 1. These results indicate that NtpI Arg-573 is indispensable for sodium translocation and for the cooperative features of E. hirae vacuolar-type ATPase.     

Hydrothermal synthesis and characterization of a two-dimensional nickel(II) complex containing benzenehexacarboxylic acid (mellitic acid)

The hydrothermal synthesis, single crystal X-ray structure and magnetic properties of a two-dimensional (2-D) coordination polymer, [Ni₄(C₆(COO)₆)(OH)₂(H₂O)₆] (1), is described. Complex 1 consists of dimer motifs of pseudo octahedral NiO₆ linked through μ3-OH to generate one-dimensional (1-D) chains which are further bridged by the mellitate ligands to form non interpenetrated undulating sheet structure. The sheets are further connected by hydrogen bonding interaction to yield a three-dimensional (3-D) structure. The temperature dependence of magnetic susceptibilities revealed the presence of antiferromagnetic interaction between nickel centers.     

An endoplasmic reticulum protein, p180, is highly expressed in human cytomegalovirus-permissive cells and interacts with the tegument protein encoded by UL48

We have used a virus overlay assay to detect cellular proteins associated with human cytomegalovirus (HCMV) particles. The radiolabeled HCMV particles specifically bound to two host proteins with molecular sizes of 150 and 180 kDa. By a micro-amino-acid sequencing technique, the 180-kDa protein was identified as a human homologue of the ES130/p180 ribosome receptor (p180), which is an integral endoplasmic reticulum (ER) membrane protein possessing a very unique tandem repeat domain at its N-terminal region. The virus overlay assay using truncated p180 polypeptides revealed that HCMV binding to human p180 occurred through the N-terminal region. In HCMV-permissive cells the high level of expression of the human p180 protein was clearly observed regardless of cell type. Furthermore, we showed that p180 binds to the UL48 gene product, which is one of the predominant tegument proteins of HCMV and which is considered to be tightly associated with the capsid. The interaction between the two proteins was assumed to be specific and was observed both in vitro and in vivo. During the late phase of infection, the unique relocation of human p180 was observed, that is, to the juxtanuclear region, which appeared to be in the vicinity of the area where naked virions were frequently observed in an electron-microscopic study. Thus our data suggest that p180 interacts with the HCMV tegument, at least through pUL48, during the HCMV replication process. We discuss the possible role of the interaction between p180 and pUL48 in the intracellular transport of HCMV virions.     

Isolation of Enterococcus hirae mutant deficient in low-affinity potassium uptake at alkaline pH

We here isolated an Enterococcus hirae mutant unable to grow well at pH 10. The influx rate calculated from steady-state 42K+/K+ exchange and the intracellular K+ concentration of the mutant were reduced to 53 and 55% of those of the wild-type, respectively. The activities of two high-affinity K+ uptake systems, KtrI and KtrII, were normal in the mutant, but the kinetics of net K+ uptake at pH 10 indicated that a low-affinity K+ uptake with a Km of about 20 mM (Kawano, M, Abuki, R, Igarashi, K, Kakinuma, Y. (2001) Arch. Microbiol. 175: 41-45), which were seen in the wild-type, was deficient in this mutant.     

Adhesive Property of <Emphasis Type="Italic">Bifidobacterium lactis</Emphasis> LKM512 and Predominant Bacteria of Intestinal Microflora to Human Intestinal Mucin

The adhesive property to the intestinal mucin of Bifidobacterium lactis LKM512, B. longum, B. breve, B. bifidum, B. adolescentis, B. infantis, Bacteroides vulgatus, Bacteroides distasonis, Eubacterium aerofaciens, Clostridium perfringens, Escherichia coli, and Lactobacillus acidophilus were examined. Adhesive rate of LKM512 to the mucin was significantly (p < 0.05, 0.01, or 0.001) stronger than the other strains from 2 to 100 time. Though the adhesive property of many strains was almost same to the mucin of 20-year-old and 50-year-old generations, in case of 4-month-old was different. Adhesive inhibitory effect of C. perfringens to the mucin by LKM512 was examined. Under the condition that LKM512 was 10⁸/ml and that C. perfringens was 10⁶/ml, adhesion of C. perfringens to the mucin was inhibited at 99.6%, when LKM512 adhered in advance. There was the strong inhibition of adhesion at 74.0%, when C. perfringens adhered to mucin in advance. Thus, LKM512 can inhibit the adhesion of harmful bacteria to the intestinal mucin, the possibility of using as a probiotic strain has to be verified.