Phosphatidyl inositol-phospholipase C in squid photoreceptor membrane is activated by stable metarhodopsin via GTP-binding protein, Gq

AbstractPhosphatidyl inositol-phospholipase C (PI-PLC) in squid retina was studied by immunoblotting and its activites were determined using [3H]phosphatidyl inositol bisphosphate ([3H]PIP2) as substrate. PI-PLC activity was found mostly in soluble fraction when the retina homogenate was treated with 400 mM KCl, but was associated with rhabdomal membranes under low salt conditions (20 mM Hepes). A protein with apparent molecular mass of 130 kD was recognized by an antibody against PLCβ4/norp A in both 400 mM KCl soluble and rhabdomal membrane fractions. A 42 kD protein recognized by antibody against the C-terminus of Gqα was also present in these two fractions. GTPγS stimulated only the PI-PLC activity associated with membrane and was magnesium dependent. PI-PLC activity was found to be (i) highly dependent upon calcium concentrations, (ii) enhanced by GTP but not by other nucleotides, and (iii) significantly stimulated by light at lower concentrations of GTPγS. The stimulation by light was still observed when irradiated membrane was incubated at 10°C for 10 min and then mixed with GTPγS. These results suggest that stable metarhodopsin stimulates a PLCβ4/norp A-like enzyme via a G-protein, Gq

L-Glutamate production by lysozyme-sensitive Corynebacterium glutamicum ltsA mutant strains

BACKGROUND: A non-pathogenic species of coryneform bacteria, Corynebacterium glutamicum, was originally isolated as an L-glutamate producing bacterium and is now used for fermentative production of various amino acids. A mutation in the C. glutamicum ltsA gene caused susceptibility to lysozyme, temperature-sensitive growth, and L-glutamate production. RESULTS: The characteristics of eight lysozyme-sensitive mutants which had been isolated after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis were examined. Complementation analysis with the cloned wild-type ltsA gene and DNA sequencing of the ItsA region revealed that four mutants had a mutation in the ltsA gene. Among them, two mutants showed temperature-sensitive growth and overproduced L-glutamate at higher temperatures, as well as the previously reported ltsA mutant. Other two showed temperature-resistant growth: one missense mutant produced L-glutamate to some extent but the other nonsense mutant did not. These two mutants remained temperature-resistant in spite of introduction of ltsA::kan mutation that causes temperature-sensitive growth in the wild-type background. CONCLUSIONS: These results indicate that a defect caused by the ltsA mutations is responsible for temperature-sensitive growth and L-glutamate overproduction by C. glutamicum. The two temperature-resistant mutants seem to carry suppressor mutations that rendered cells temperature-resistance and abolished L-glutamate overproduction

Positivity and Hierarchical Structure of four Green Functions Corresponding to a Bending Problem of a Beam on a half line

We consider the boundary value problem for fourth order linear ordinary differential equation in a half line (0,∞), which represents bending of a beam on an elastic foundation under a tension. A tension is relatively stronger than a spring constant of elastic foundation. We here treat four self-adjoint boundary conditions, clamped, Dirichlet, Neumann and free edges, at x = 0. We show the positivity and the hierarchical structure of four Green functions

Sphingosine 1-phosphate (S1P) inhibits monocyte–endothelial cell interaction by regulating of RhoA activity

AbstractRecent studies suggest that sphingosine 1-phosphate (S1P) protects against atherosclerosis. We assessed the effects of S1P on monocyte–endothelial interaction in the presence of inflammatory mediators. Pretreatment of THP-1 cells with S1P abolished Phorbol 12 myristate 13-acetate (PMA)-induced THP-1 cell adhesion to human umbilical vein endothelial cells (HUVECs). S1P inhibited PMA-induced activation of RhoA, but not PKCs. S1P activated p190Rho GTPase activation protein (GAP) only in the presence of PMA, suggesting an inhibitory effect of S1P and PMA to suppress RhoA. In conclusion, S1P inhibited monocyte–endothelial interactions by inhibiting RhoA activity which may explain its anti-atherogenic effects

28 教育学は経験科学か規範科学か？ ＜神奈川大学創立三五周年記念論文集＞

第三

Complete mitochondrial genome sequences for Crown-of-thorns starfish Acanthaster planci and Acanthaster brevispinus

BACKGROUND: The crown-of-thorns starfish, Acanthaster planci (L.), has been blamed for coral mortality in a large number of coral reef systems situated in the Indo-Pacific region. Because of its high fecundity and the long duration of the pelagic larval stage, the mechanism of outbreaks may be related to its meta-population dynamics, which should be examined by larval sampling and population genetic analysis. However, A. planci larvae have undistinguished morphological features compared with other asteroid larvae, hence it has been difficult to discriminate A. planci larvae in plankton samples without species-specific markers. Also, no tools are available to reveal the dispersal pathway of A. planci larvae. Therefore the development of highly polymorphic genetic markers has the potential to overcome these difficulties. To obtain genomic information for these purposes, the complete nucleotide sequences of the mitochondrial genome of A. planci and its putative sibling species, A. brevispinus were determined and their characteristics discussed. RESULTS: The complete mtDNA of A. planci and A. brevispinus are 16,234 bp and 16,254 bp in size, respectively. These values fall within the length variation range reported for other metazoan mitochondrial genomes. They contain 13 proteins, 2 rRNA, and 22 tRNA genes and the putative control region in the same order as the asteroid, Asterina pectinifera. The A + T contents of A. planci and A. brevispinus on their L strands that encode the majority of protein-coding genes are 56.3% and 56.4% respectively and are lower than that of A. pectinifera (61.2%). The percent similarity of nucleotide sequences between A. planci and A. brevispinus is found to be highest in the CO2 and CO3 regions (both 90.6%) and lowest in ND2 gene (84.2%) among the 13 protein-coding genes. In the deduced putative amino acid sequences, CO1 is highly conserved (99.2%), and ATP8 apparently evolves faster any of the other protein-coding gene (85.2%). CONCLUSION: The gene arrangement, base composition, codon usage and tRNA structure of A. planci are similar to those of A. brevispinus. However, there are significant variations between A. planci and A. brevispinus. Complete mtDNA sequences are useful for the study of phylogeny, larval detection and population genetics

Quantitative evaluation of temporal partial coherence using 3D Fourier transforms of through-focus TEM images

AbstractWe evaluate the temporal partial coherence of transmission electron microscopy (TEM) using the three-dimensional (3D) Fourier transform (FT) of through-focus images. Young's fringe method often indicates the unexpected high-frequency information due to non-linear imaging terms. We have already used the 3D FT of axial (non-tilted) through-focus images to reduce the effect of non-linear terms on the linear imaging term, and demonstrated the improvement of monochromated lower-voltage TEM performance [Kimoto et al., Ultramicroscopy 121 (2012) 31–39]. Here we apply the 3D FT method with intentionally tilted incidence to normalize various factors associated with a TEM specimen and an imaging device. The temporal partial coherence of two microscopes operated at 30, 60 and 80kV is evaluated. Our method is applicable to such cases where the non-linear terms become more significant in lower acceleration voltage or aberration-corrected high spatial resolution TEM