How meristem plasticity in response to soil nutrients and light affects plant growth in four Festuca grass species.

Investigation of responses of meristems to environmental conditions is important for understanding the mechanisms and consequences of plant phenotypic plasticity. Here, we examined how meristem plasticity to light and soil nutrients affected leaf growth and relative growth rate (RGR) in fast- and slow-growing Festuca grass species. Activity in shoot apical meristems was measured by leaf appearance rate, and that in leaf meristems by the duration and rate of cell production, which was further divided into single cell cycle time and the number of dividing cells. Light and soil nutrients affected activity in shoot apical meristems similarly. The high nutrient supply increased the number of dividing cells, which was responsible for enhancement of cell production rate; shaded conditions extended the duration of cell production. As a result, leaf length increased under high nutrient and shaded conditions. The RGR was correlated positively with the total meristem size of the shoot under a low nutrient supply, implying inhibition of RGR by cell production under nutrient-limited conditions. Fast-growing species were more plastic for cell production rate and specific leaf area (SLA) but less plastic for RGR than slow-growing species. This study demonstrates that meristem plasticity plays key roles in characterizing environmental responses of plant species.

Masked t(15;17) APL with the insertion of PML-RARalpha fusion gene in 4q21.

Most cases of acute promyelocytic leukemia (APL) are characterized by the reciprocal translocation t(15;17); however, several complex variant translocations have also been reported. Here we report complex cytogenetic abnormalities without t(15;17) assayed by the G-banding method in a 62-year-old woman with the typical morphology and clinical features of APL. Based on spectral karyotyping and FISH analyses, we confirm the insertion of a cryptic chromosomal segment containing the PML/RARalpha fusion gene. The patient achieved complete remission after treatment with all-trans retinoic acid (ATRA) alone. Although the mechanism of this cryptic variant insertion is not known, we conclude that the insertion of PML-RARalpha fusion into 4q21 seems not to alter the effectiveness of treatment with ATRA.

Establishment of CD5 and CD10 double-positive mature B-cell line, WILL1, showing complex 8q24 translocation involving 14q32 and 6q27.

We established a novel mature B-cell line from a CD5 and CD10 double-positive diffuse large B-cell lymphoma patient, designated as WILL1. WILL1 cells were positive for CD5, CD10, CD19, and CD20. Spectral karyotype (SKY) analysis revealed chromosome 8 signals on 6q27 as well as 14q32. Fluorescence in situ hybridization (FISH) analysis suggested that a translocation break occurred outside the immunoglobulin heavy chain (IGH) gene on 14q32. Moreover, fusion signals of IGH and C-MYC probes were detected on the derivative 6 and derivative 14 chromosomes. Southern blot analysis using a C-MYC exon II fragment failed to detect rearrangement, suggesting that the 8q24 breakpoints lay far up- or downstream of the C-MYC gene. WILL1 is a useful tool to analyze the pathogenesis of CD5 and CD10 double-positive diffuse large B-cell lymphoma, and for molecular cloning of the unique translocation breakpoints of 14q32 and 8q24 and a novel gene on 6q27.