Comparison between humic-like peaks in excitation-emission matrix spectra and resin-fractionated humic substances in aquatic environments

Limnology - The intensity of the 340/430-nm peak in the three-dimensional excitation-emission matrix spectra of water samples has been used as an index of the concentration of aquatic humic...     

Hydrodynamic interactions between two swimming bacteria

This article evaluates the hydrodynamic interactions between two swimming bacteria precisely. We assume that each bacterium is force free and torque free, with a Stokes flow field around it. The geometry of each bacterium is modeled as a spherical or spheroidal body with a single helical flagellum. The movements of two interacting bacteria in an infinite fluid otherwise at rest are computed using a boundary element method, and the trajectories of the two interacting bacteria and the stresslet are investigated. The results show that as the two bacteria approach each other, they change their orientations considerably in the near field. The bacteria always avoided each other; no stable pairwise swimming motion was observed in this study. The effects of the hydrodynamic interactions between two bacteria on the rheology and diffusivity of a semidilute bacterial suspension are discussed.     

Thrombomodulin is a clock-controlled gene in vascular endothelial cells

Cardiovascular diseases are closely related to circadian rhythm, which is under the control of an internal biological clock mechanism. Although a biological clock exists not only in the hypothalamus but also in each peripheral tissue, the biological relevance of the peripheral clock remains to be elucidated. In this study we searched for clock-controlled genes in vascular endothelial cells using microarray technology. The expression of a total of 229 genes was up-regulated by CLOCK/BMAL2. Among the genes that we identified, we examined the thrombomodulin (TM) gene further, because TM is an integral membrane glycoprotein that is expressed primarily in vascular endothelial cells and plays a major role in the regulation of intravascular coagulation. TM mRNA and protein expression showed a clear circadian oscillation in the mouse lung and heart. Reporter analyses, gel shift assays, and chromatin immunoprecipitation analyses using the TM promoter revealed that a heterodimer of CLOCK and BMAL2 binds directly to the E-box of the TM promoter, resulting in TM promoter transactivation. Indeed, the oscillation of TM gene expression was abolished in clock mutant mice, suggesting that TM expression is regulated by the clock gene in vivo. Finally, the phase of circadian oscillation of TM mRNA expression was altered by temporal feeding restriction, suggesting TM gene expression is regulated by the peripheral clock system. In conclusion, these data suggest that the peripheral clock in vascular endothelial cells regulates TM gene expression and that the oscillation of TM expression may contribute to the circadian variation of cardiovascular events.     

Population dynamics of the harmful diatom Eucampia zodiacus Ehrenberg causing bleachings of Porphyra thalli in aquaculture in Harima-Nada, the Seto Inland Sea, Japan

The diatom Eucampia zodiacus Ehrenberg is one of the harmful diatom species which indirectly cause bleachings of Nori (Porphyra thalli) in aquaculture through competitive utilizing of nutrients (especially nitrogen) and resultant nutrient depletion in water columns during the bloom events. The seasonal changes in environmental factors, cell density and cell size of E. zodiacus were investigated for 4 years (April 2002–December 2005) to understand the population ecology of this diatom in Harima-Nada, the eastern part of the Seto Inland Sea, Japan. Vegetative cells of E. zodiacus were usually detected year-round. Total cell densities of E. zodiacus annually peaked from mid-February to early April, and high cell densities were observed in the whole water columns during the bloom-period. Nutrient concentrations decreased with the increase of cell density of E. zodiacus, and low nutrients concentrations continued throughout the E. zodiacus bloom-period. The average cell size (length of apical axis) of E. zodiacus populations ranged from 10.8 μm to 81.2 μm, and the restoration of cell size occurred once in autumn every year just after reaching the minimum cell size. In addition, its great seasonal regularity was confirmed by the decrease and restoration of its cell size through 4-year study period. Temperature and nutrients were suitable in autumn for the growth of E. zodiacus, its blooms never occur in that season. These results strongly suggest that E. zodiacus did not have a resting stage, and it spends autumn for size restoration and starts to bloom thereafter in Harima-Nada in winter and spring, causing fishery damage to Nori aquaculture by resulting nutrient deprivation.     

Chromosome-Scale Genome Assembly of the Marine Oleaginous Diatom Fistulifera solaris

Marine Biotechnology - Microalgae including diatoms are of interest for environmentally friendly manufacturing such as production of biofuels, chemicals, and materials. The highly oil-accumulating...     

Successful implantation of in vitro cultured rabbit embryos after uterine transfer: A role for mucin

The functional role of the mucin layer for development of rabbit embryos was examined by uterine transfer of embryos with different thicknesses of mucin. Embryos collected at various intervals after human chorionic gonadotropin (hCG) injection were cultured until 90 hr post-coitum (p.c.) and transferred to the uterus of synchronized recipients. When embryos collected at 20 or 25 hr p.c. were used for transfer, no implantation occurred. By contrast, embryos collected at 35 or 40 hr p.c. developed to term at high rates (53 and 80%, respectively). The thickness of the mucin layer on the embryos was different between these two groups. Embryos collected before 25 hr p.c. have less than 11.2 ± 0.2 μm of thickness of mucin and embryos collected after 35 hr p.c. have more than 34.3 ± 5.5 μm. To examine whether mucin deposition is required for in vitro cultured rabbit blastocysts to continue development after uterine transfer, embryos were collected at 20 hr p.c., cultured for 60 or 70 hr in vitro, and then temporarily transferred to the oviducts of recipient does to add mucin. These embryos were recovered from the oviducts at 24 hr after transfer, classified according to the thickness of mucin deposition, and transferred again to the uterus of synchronized recipients. Twenty live young were obtained from 67 embryos with a 20–40 μm thick mucin layer. No live young were obtained from 57 embryos with less than a 20 μm thick mucin. The thickness of the mucin layer appears to be an important factor for successful implantation of rabbit embryos. © 1996 Wiley-Liss, Inc.     

Occurrence and subcellular location of NADH- and NADPH-linked aquacobalamin reductases in human liver

1. Both activities of NADH- and NADPH-linked aquacobalamin reductases were found in some human tissues, liver, kidney pancreas, heart, spleen, lung, cerebrum, cerebellum, adrenal glands, stomach, duodenum, jejunum, ileum, colon and bone marrow. 2. Human liver contained both enzymes with higher specific activities than any other tissues. 3. The liver NADH-linked enzyme was distributed in both mitochondrial (approx. 60%) and microsomal (40%) fractions; similar to the distribution of the NADPH-linked enzyme, but of which 40% activity was found in the mitochondria and the remaining activity was recovered in the microsomes. 4. The results suggest that the synthetic systems of the cobalamin coenzymes occur in both mitochondria and microsomes of human liver.     

Disruption of phospholipase B gene, PLB1, increases the survival of baker's yeast Torulaspora delbrueckii

Abstract An uracil auxotrophic mutant of baker's yeast Torulaspora delbrueckii , which is resitant to 5-fluoro-orotic acid, was complemented by transformation with YEp24 which harbors 2 μm origin and URA3 derived from Saccharomyces cerevisiae . The phospholipase B in T. delbrueckii cells is active in both acidic and alkaline conditions. However, activity of phospholipase B gene ( PLB1 ) in cells of disruption mutant ( plbI : : URA3 ) was lost in both conditions, which indicates that all phospholipase B activity is encoded by a single gene (or a single polypeptide) in these yeast cells. Over-expression of PLB1 with YEp plasmid vector in T. delbrueckii cells showed ∼ 2.5-fold increase in phospholipase B activity, comparing with that in wild-type cells. Cells of plb1 Δ mutant showed increased survival when cells of plb1 Δ mutant and wild-type strain were incubated in water at 30 °C. Cells of PLB1 -over-expressed strain died rapidly even during the cultivation period, indicating that phospholipase B activity may be a determinant for the survival of this yeast.     

A factor of inducing IgE from a filarial parasite is an agonist of human CD40

Immune responses to parasitic helminth are usually characterized by quite mysterious phenomena: dominance of Th2-like immunity and antigen-nonspecific IgE secretion. We previously purified a factor from Dirofilaria immitis that induces antigen-nonspecific IgE in rats and named it DiAg. In the presence of IL-4, DiAg induces mouse B cells to secrete IgE, which is antigen-nonspecific polyclonal antibody. We investigated the biochemical characteristics of DiAg as a factor of inducing IgE in this study. Recombinant DiAg (rDiAg) with interleukin (IL)-4 induced IgE synthesis in highly purified human normal B cells in vitro cell culture systems. The addition of recombinant human soluble CD40 IgG fusion protein (rsCD40-Ig) inhibited induction of IgE synthesis by rDiAg with IL-4. Monocyte cells were stimulated with rDiAg and recombinant human soluble CD40L (rsCD40L); IL-12 and TNF-alpha were induced. The addition of rsCD40-Ig to THP-1 cells activated with rDiAg and rsCD40L inhibited the production of IL-12. rDiAg bound to the monocyte cell membrane fraction and recombinant human soluble CD40; this binding of rDiAg was competitively inhibited by addition of rsCD40L. Moreover, in CD40-deficient mice, IgE production and MLN-B cell proliferation by rDiAg were completely absent. Based on these results, we concluded that DiAg is an agonist of CD40.