EVALUATION OF XYLEM MATURTATION PROCESS AND EFFECTS OF RADIAL GROWTH RATE ON CELL MORPHOLOGIES IN WOOD OF BALSA (OCHROMA PRYAMIDALE) TREES

The radial variations of cell morphologies (cell lengths, vessel diameter, vessel frequency and cell wall thickness of wood fibers) were investigated for 7-year-old Ochroma pyramidale trees planted in East Java, Indonesia by developing the linear or nonlinear mixed-effects models. In addition, xylem maturation process based on the cell morphologies and effects of radial growth rate on cell morphologies were discussed. The mean values of cell morphology were as follow: vessel element length 0.59 mm, fiber length 2.16 mm, vessel diameter 221 µm, and fiber wall thickness 1.03 µm. Radial variations of cell length and vessel diameter were well explained by Michaelis-Menten equation: values increased from pith to certain position and then it became almost stable. Vessel frequency, wood fiber diameter, and wood fiber wall thickness was expressed by the formula of logarithmic formula, quadratic formula, and linear formula, respectively. Variance component ration of category was 66.8%, 46.1%, 31.4%, 1.5%, and 33.7% for vessel element length, wood fiber length, vessel diameter, vessel frequency, and wood fiber wall thickness, respectively, suggesting that many cell morphologies influenced by the radial growth rate. Smaller values of mean absolute error obtained in the models in relation to distance from pith were found in all cell morphologies, except for vessel frequency and wood fiber diameter. Thus, xylem maturation of this species depended on diameter growth rather than cambial age. Boundary of core wood and outer wood was 5 to 10 cm from pith in which increasing ratio of cell length reached less than 0.3%. Core wood was characterized as lower wood density and mechanical properties with shorter cell lengths and thinner wood fiber walls, whereas outer wood was characterized as higher wood density and mechanical properties with longer cell length and thicker wood fiber walls

Pressure-induced valence anomaly in TmTe probed by resonant inelastic x-ray scattering

The pressure-induced valence transition in TmTe was investigated by resonant inelastic x-ray scattering at the Tm L(3) edge, a powerful probe of the rare-earth valent state. The data are analyzed within the Anderson impurity model which yields key parameters such as the Tm 4f-5d hybridization. In addition to the general tendency of the f electrons towards delocalization, we find a plateau in both the Tm valence and hybridization pressure dependences between 4.3 and 6.5 GPa which is interpreted in terms of an n-channel Kondo (NCK) screening process. This behavior is at odds with the usually continuous, single-channel Kondo-like f delocalization while being supported by the seminal calculations of the NCK temperature in Tm ion by Saso et al. Our study raises the interesting possibility that an NCK effect realized in a compressed mixed-valent f system could impede the concomitant electron delocalization

Aneuploidy Drives Genomic Instability in Yeast

Aneuploidy decreases cellular fitness, yet it is also associated with cancer, a disease of enhanced proliferative capacity. To investigate one mechanism by which aneuploidy could contribute to tumorigenesis, we examined the effects of aneuploidy on genomic stability. We analyzed 13 budding yeast strains that carry extra copies of single chromosomes and found that all aneuploid strains exhibited one or more forms of genomic instability. Most strains displayed increased chromosome loss and mitotic recombination, as well as defective DNA damage repair. Aneuploid fission yeast strains also exhibited defects in mitotic recombination. Aneuploidy-induced genomic instability could facilitate the development of genetic alterations that drive malignant growth in cancer

Valence Fluctuations Revealed by Magnetic Field Scan: Comparison with Experiments in YbXCu_4 (X=In, Ag, Cd) and CeYIn_5 (Y=Ir, Rh)

The mechanism of how critical end points of the first-order valence transitions (FOVT) are controlled by a magnetic field is discussed. We demonstrate that the critical temperature is suppressed to be a quantum critical point (QCP) by a magnetic field. This results explain the field dependence of the isostructural FOVT observed in Ce metal and YbInCu_4. Magnetic field scan can lead to reenter in a critical valence fluctuation region. Even in the intermediate-valence materials, the QCP is induced by applying a magnetic field, at which the magnetic susceptibility also diverges. The driving force of the field-induced QCP is shown to be a cooperative phenomenon of the Zeeman effect and the Kondo effect, which creates a distinct energy scale from the Kondo temperature. The key concept is that the closeness to the QCP of the FOVT is capital in understanding Ce- and Yb-based heavy fermions. It explains the peculiar magnetic and transport responses in CeYIn_5 (Y=Ir, Rh) and metamagnetic transition in YbXCu_4 for X=In as well as the sharp contrast between X=Ag and Cd.Comment: 14 pages, 9 figures, OPEN SELECT in J. Phys. Soc. Jp

Anomalous Transport Phenomena in Fermi Liquids with Strong Magnetic Fluctuations

In many strongly correlated electron systems, remarkable violation of the relaxation time approximation (RTA) is observed. The most famous example would be high-Tc superconductors (HTSCs), and similar anomalous transport phenomena have been observed in metals near their antiferromagnetic (AF) quantum critical point (QCP). Here, we develop a transport theory involving resistivity and Hall coefficient on the basis of the microscopic Fermi liquid theory, by considering the current vertex correction (CVC). In nearly AF Fermi liquids, the CVC accounts for the significant enhancements in the Hall coefficient, magnetoresistance, thermoelectric power, and Nernst coefficient in nearly AF metals. According to the numerical study, aspects of anomalous transport phenomena in HTSC are explained in a unified way by considering the CVC, without introducing any fitting parameters; this strongly supports the idea that HTSCs are Fermi liquids with strong AF fluctuations. In addition, the striking \omega-dependence of the AC Hall coefficient and the remarkable effects of impurities on the transport coefficients in HTSCs appear to fit naturally into the present theory. The present theory also explains very similar anomalous transport phenomena occurring in CeCoIn5 and CeRhIn5, which is a heavy-fermion system near the AF QCP, and in the organic superconductor \kappa-(BEDT-TTF).Comment: 100 pages, Rep. Prog. Phys. 71, 026501 (2008

A duplication at chromosome 11q12.2–11q12.3 is associated with spinocerebellar ataxia type 20

Spinocerebellar ataxia type 20 (SCA20) has been linked to chromosome 11q12, but the underlying genetic defect has yet to be identified. We applied single-nucleotide polymorphism genotyping to detect structural alterations in the genomic DNA of patients with SCA20. We found a 260 kb duplication within the previously linked SCA20 region, which was confirmed by quantitative polymerase chain reaction and fiber fluorescence in situ hybridization, the latter also showing its direct orientation. The duplication spans 10 known and 2 unknown genes, and is present in all affected individuals in the single reported SCA20 pedigree. While the mechanism whereby this duplication may be pathogenic remains to be established, we speculate that the critical gene within the duplicated segment may be DAGLA, the product of which is normally present at the base of Purkinje cell dendritic spines and contributes to the modulation of parallel fiber-Purkinje cell synapses

Evidence for a nuclear compartment of transcription and splicing located at chromosome domain boundaries

The nuclear topography of splicing snRNPs, mRNA transcripts and chromosome domains in various mammalian cell types are described. The visualization of splicing snRNPs, defined by the Sm antigen, and coiled bodies, revealed distinctly different distribution patterns in these cell types. Heat shock experiments confirmed that the distribution patterns also depend on physiological parameters. Using a combination of fluorescencein situ hybridization and immunodetection protocols, individual chromosome domains were visualized simultaneously with the Sm antigen or the transcript of an integrated human papilloma virus genome. Three-dimensional analysis of fluorescence-stained target regions was performed by confocal laser scanning microscopy. RNA transcripts and components of the splicing machinery were found to be generally excluded from the interior of the territories occupied by the individual chromosomes. Based on these findings we present a model for the functional compartmentalization of the cell nucleus. According to this model the space between chromosome domains, including the surface areas of these domains, defines a three-dimensional network-like compartment, termed the interchromosome domain (ICD) compartment, in which transcription and splicing of mRNA occurs

A Strategy for the Proliferation of Ulva prolifera, Main Causative Species of Green Tides, with Formation of Sporangia by Fragmentation

Ulva prolifera, a common green seaweed, is one of the causative species of green tides that occurred frequently along the shores of Qingdao in 2008 and had detrimental effects on the preparations for the 2008 Beijing Olympic Games sailing competition, since more than 30 percent of the area of the games was invaded. In view of the rapid accumulation of the vast biomass of floating U. prolifera in green tides, we investigated the formation of sporangia in disks of different diameters excised from U. prolifera, changes of the photosynthetic properties of cells during sporangia formation, and development of spores. The results suggested that disks less than 1.00 mm in diameter were optimal for the formation of sporangia, but there was a small amount of spore release in these. The highest percentage of area of spore release occurred in disks that were 2.50 mm in diameter. In contrast, sporangia were formed only at the cut edges of larger disks (3.00 mm, 3.50 mm, and 4.00 mm in diameter). Additionally, the majority of spores liberated from the disks appeared vigorous and developed successfully into new individuals. These results implied that fragments of the appropriate size from the U. prolifera thalli broken by a variety of factors via producing spores gave rise to the rapid proliferation of the seaweed under field conditions, which may be one of the most important factors to the rapid accumulation of the vast biomass of U. prolifera in the green tide that occurred in Qingdao, 2008