Second‐harmonic generation from Langmuir–Blodgett film of cyclic peptide carrying two disperse red 1 on fused quartz surface

Cyclic octapeptide carrying one or two nonlinear optical chromophores, disperse red 1 (DR‐1), was synthesized and immobilized on a substrate to attain an active surface for second‐harmonic generation (SHG). Each cyclic octapeptide was transferred on a fused quartz substrate by the Langmuir–Blodgett (LB) method to afford a uniform monolayer. Infrared reflection–absorption spectroscopy of the LB monolayer revealed that the cyclic skeleton lay roughly flat on the surface. The SHG intensity from the monolayer of the cyclic peptide with two DR‐1 units was stronger than that from that with one DR‐1 unit. The difference is discussed in terms of molecular orientation and surface density of the active chromophores. The cyclic peptide is shown here to be an effective scaffold to modify a substrate surface with functional groups of a monolayer with taking stability of the monolayer and orientation of the functional group into consideration. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.     

Infection dynamics of coexisting beta- and gammaproteobacteria in the nested endosymbiotic system of mealybugs

We investigated the infection dynamics of endosymbiotic bacteria in the developmental course of the mealybugs Planococcus kraunhiae and Pseudococcus comstocki. Molecular phylogenetic analyses identified a betaproteobacterium and a gammaproteobacterium from each of the mealybug species. The former bacterium was related to the beta-endosymbionts of other mealybugs, i.e., "Candidatus Tremblaya princeps," and formed a compact clade in the Betaproteobacteria. Meanwhile, the latter bacterium was related to the gamma-endosymbionts of other mealybugs but belonged to distinct clades in the Gammaproteobacteria. Whole-mount in situ hybridization confirmed the peculiar nested formation in the endosymbiotic system of the mealybugs: the beta-endosymbiont cells were present in the cytoplasm of the bacteriocytes, and the gamma-endosymbiont cells were located in the beta-endosymbiont cells. In nymphal and female development, a large oval bacteriome consisting of a number of bacteriocytes was present in the abdomen, wherein the endosymbionts were harbored. In male development, strikingly, the bacteriome progressively degenerated in prepupae and pupae and became almost unrecognizable in adult males. In the degeneration process, the gamma-endosymbionts disappeared more rapidly than the beta-endosymbionts did. Quantitative PCR analyses revealed that (i) the population dynamics of the endosymbionts in female development reflected the reproductive activity of the insects, (ii) the population dynamics of the endosymbionts were strikingly different between female development and male development, (iii) the endosymbiont populations drastically decreased in male development, and (iv) the gamma-endosymbiont populations decreased more rapidly than the beta-endosymbiont populations in male development. Possible mechanisms underlying the uncoupled regulation of the beta- and gamma-endosymbiont populations are discussed in relation to the establishment and evolution of this unique prokaryote-prokaryote endosymbiotic system.     

An analysis of long-distance water transport in the soybean stem using H215O

The lateral water movement in the intact stem of a transpiring soybean plant was analyzed quantitatively by a real-time measurement system utilizing labeled water, H(2)(15)O and gamma ray detectors. A large volume of water escaping from xylem vessels during its transport was detected. The escape of water was not influenced by evaporation from the stem surface or mass flow in the sieve tubes. It was assumed that the total amount of water transported through xylem vessels was kept almost completely constant along the internode. As a result, most of the escaped water was found to re-enter the xylem vessels, i.e. water exchange occurred. The analysis of radiographs of tritiated water suggested that the self-diffusion effect of water was strong for lateral water movement, although another driving force besides thermal motion was included in the process, and that the process was also affected by the water permeability of the plasma membrane. An analysis based on a mathematical model showed that the net volume of water which escaped from xylem vessels was not dependent on the transpiration rate of the plant.     

Ventilatory long-term facilitation in mice can be observed during both sleep and wake periods and depends on orexin.

Respiratory long-term facilitation (LTF) is a long-lasting (>1 h) augmentation of respiratory motor output that occurs even after cessation of hypoxic stimuli, is serotonin-dependent, and is thought to prevent sleep-disordered breathing such as sleep apnea. Raphe nuclei, which modulate several physiological functions through serotonin, receive dense projections from orexin-containing neurons in the hypothalamus. We examined possible contributions of orexin to ventilatory LTF by measuring respiration in freely moving prepro-orexin knockout mice (ORX-KO) and wild-type (WT) littermates before, during, and after exposure to intermittent hypoxia (IH; 5 x 5 min at 10% O2), sustained hypoxia (SH; 25 min at 10% O2), or sham stimulation. Respiratory data during quiet wakefulness (QW), slow wave sleep (SWS), and rapid-eye-movement sleep were separately calculated. Baseline ventilation before hypoxic stimulation and acute responses during stimulation did not differ between the ORX-KO and WT mice, although ventilation depended on vigilance state. Whereas the WT showed augmented minute ventilation (by 20.0 +/- 4.5% during QW and 26.5 +/- 5.3% during SWS; n = 8) for 2 h following IH, ORX-KO showed no significant increase (by -3.1 +/- 4.6% during QW and 0.3 +/- 5.2% during SWS; n = 8). Both genotypes showed no LTF after SH or sham stimulation. Sleep apnea indexes did not change following IH, even when LTF appeared in the WT mice. We conclude that LTF occurs during both sleep and wake periods, that orexin is necessary for eliciting LTF, and that LTF cannot prevent sleep apnea, at least in mice.     

Contactin-2/TAG-1, active on the front line for three decades

Contactin-2/transiently expressed axonal surface glycoprotein-1 (TAG-1) is a cell adhesion molecule belonging to the immunoglobulin superfamily (IgSF). It has six immunoglobulin-like extracellular domains and four fibronectin III-like ones, with anchoring to the cell membrane through glycosylphosphatidyl inositol. Contactin-2/TAG-1 is expressed in specific neurons transiently on the axonal surface during the fetal period. In postnatal stages, Contactin-2/TAG-1 is expressed in cerebellar granule cells, hippocampal pyramidal cells, and the juxtaparanodal regions of myelinated nerve fibers. In the embryonic nervous system, Contactin-2/TAG-1 plays important roles in axonal elongation, axonal guidance, and cellular migration. In the postnatal nervous system, it also plays an essential role in the formation of myelinated nerve fibers. Moreover, Contactin-2/TAG-1 has been linked to autoimmune diseases of the human nervous system. Taken together, Contactin-2/TAG-1 plays a central role in a variety of functions from development to disease.     

Choline and betaine ameliorate liver lipid accumulation induced by vitamin B6 deficiency in rats

We investigated the efficacy of supplementing the diet with choline or betaine in ameliorating lipid accumulation induced by vitamin B₆ (B₆) deficiency in rat liver. Male Wistar rats were fed a control, B₆-deficient, choline-supplemented (2, 4, or 6 g choline bitartrate/kg diet) B₆-deficient diet or betaine-supplemented (1, 2, or 4 g betaine anhydrous/kg diet) B₆-deficient diet for 35 d; all diets contained 9 g L-methionine (Met)/kg diet. Choline or betaine supplementation attenuated liver lipid deposition and restored plasma lipid profiles to control levels. These treatments restored the disruptions in Met metabolism and the phosphatidylcholine (PC)/phosphatidylethanolamine (PE) ratio induced by B₆ deficiency in liver microsomes. These results suggest that choline and betaine ameliorated liver lipid accumulation induced by B₆ deficiency via recovery of Met metabolism and very low-density lipoprotein secretion by restoring the supply of PC derived from PE.     

<Emphasis Type="Italic">Lactobacillus paracasei</Emphasis> strain 06TCa19 suppresses inflammatory chemokine induced by <Emphasis Type="Italic">Helicobacter pylori</Emphasis> in human gastric epithelial cells

Helicobacter (H.) pylori infection is an important risk factor for gastric cancer that causes gastric inflammation. Inflammatory chemokines such as interleukin (IL)-8 and regulated on activation normal T cell expressed and secreted (RANTES) are elevated in the gastric mucosa by H. pylori. This study aimed to investigate the effects of Lactobacillus paracasei strain 06TCa19, a probiotic strain, on IL-8 and RANTES expression and production induced by H. pylori using human gastric epithelial cell lines. Strain 06TCa19 was shown to suppress H. pylori-mediated elevation of gene expression related to these chemokines in MKN45 cells. The strain also suppressed the increase in IL-8 and RANTES products induced by H. pylori in AGS cells as well as in MKN45 cells. In MKN45 cells inoculated with H. pylori, strain 06TCa19 was shown to downregulate the activation of NF-κB and p38 MAPK signaling pathways. Additionally, the level of the CagA virulence protein of H. pylori in the MKN45 cells and the number of viable H. pylori adhering to MKN45 cells decreased with the addition of strain 06TCa19. Moreover, the strain 06TCa19 notably increased lactic acid in the supernatant of MKN45 cells. Thus, lactic acid released from strain 06TCa19 might have inhibited the adhesion of H. pylori to MKN45 cells and prevented the insertion of H. pylori CagA into the cells, and elevation of IL-8 and RANTES genes and proteins might be suppressed by downregulating the NF-κB and p38 MAPK pathways. Therefore, use of strain 06TCa19 may prevent H. pylori-associated gastric inflammation.     

Establishment and characterization of a novel uterine carcinosarcoma cell line,TU-ECS-1, with mutations of <Emphasis Type="Italic">TP53</Emphasis> and <Emphasis Type="Italic">KRAS</Emphasis>

A new human uterine carcinosarcoma (UCS) cell line, TU-ECS-1, was established and characterized. The morphological appearance of the cultured cells was an insular of epithelial-like cells arranged in the form of a jigsaw puzzle and mesenchymal-like cells with a spindle-shaped or fibroblast-like morphology. A relatively high proliferation rate was observed with a doubling time of 18.2 h. The chromosome number ranged from 44 to 49 and had an extra chromosome 12 (trisomy 12). The respective half-maximal inhibitory concentrations of cisplatin, paclitaxel, and doxorubicin were 2.9 µM, 154 nM, and 219 ng/mL, respectively. Mutational analysis revealed that TU-ECS-1 cells have mutations of TP53 in exons 4, 6, and 8 and of KRAS at codon 12 (G12D) in exon 2, which is a mutation hot spot on this gene. Western blot analysis showed that p53 protein was overexpressed in TU-ECS-1 cells. Immunostaining of the cultured cells and in vivo tumors showed that the TU-ECS-1 cells and xenografts were positive for epithelial marker cytokeratin AE1/3 and mesenchymal marker vimentin. These results suggested that TU-ECS-1 cells might have both epithelial and mesenchymal characteristics. This cell line may be useful to study the carcinogenesis of UCS and contribute to the development of novel treatment strategies.     

Quinolone resistance-associated amino acid substitutions affect enzymatic activity of Mycobacterium leprae DNA gyrase

Quinolones are important antimicrobials for treatment of leprosy, a chronic infectious disease caused by Mycobacterium leprae. Although it is well known that mutations in DNA gyrase are responsible for quinolone resistance, the effect of those mutations on the enzymatic activity is yet to be studied in depth. Hence, we conducted in vitro assays to observe supercoiling reactions of wild type and mutated M. leprae DNA gyrases. DNA gyrase with amino acid substitution Ala91Val possessed the highest activity among the mutants. DNA gyrase with Gly89Cys showed the lowest level of activity despite being found in clinical strains, but it supercoiled DNA like the wild type does if applied at a sufficient concentration. In addition, patterns of time-dependent conversion from relaxed circular DNA into supercoiled DNA by DNA gyrases with clinically unreported Asp95Gly and Asp95Asn were observed to be distinct from those by the other DNA gyrases.