Carotenoids are yellow, orange, and red pigments that contribute to the beautiful colors and nutritive value of many flowers and fruits. The structural genes in the highly conserved carotenoid ...biosynthetic pathway have been well characterized in multiple plant systems, but little is known about the transcription factors that control the expression of these structural genes. By analyzing a chemically induced mutant of Mimulus lewisii through bulk segregant analysis and transgenic experiments, we have identified an R2R3‐MYB, Reduced Carotenoid Pigmentation 1 (RCP1), as the first transcription factor that positively regulates carotenoid biosynthesis during flower development. Loss‐of‐function mutations in RCP1 lead to down‐regulation of all carotenoid biosynthetic genes and reduced carotenoid content in M. lewisii flowers, a phenotype recapitulated by RNA interference in the wild‐type background. Overexpression of this gene in the rcp1 mutant background restores carotenoid production and, unexpectedly, results in simultaneous decrease of anthocyanin production in some transgenic lines by down‐regulating the expression of an activator of anthocyanin biosynthesis. Identification of transcriptional regulators of carotenoid biosynthesis provides the ‘toolbox’ genes for understanding the molecular basis of flower color diversification in nature and for potential enhancement of carotenoid production in crop plants via genetic engineering.
We have investigated the effect of carbon on the coercivity and microstructure in fine-grained Nd-Fe-B sintered magnets fabricated by the pressless sintering method. The coercivity of the sample with ...the carbon content of 730ppm (low-C) was 1.59T while that of the sample with 1500ppm (high-C) was 1.44T in the as-sintered state. The low-C sample exhibited a larger coercivity increase by a post-sinter annealing, reaching the highest coercivity of 1.85T, while the high-C sample reached a lower coercivity of 1.54T. Detailed microstructure investigations using scanning electron microscopy, scanning transmission electron microscopy and atom probe tomography revealed that the high carbon content resulted in the formation of a Nd-carbide with a tetragonal structure and the reduction in the volume fraction of an alpha -Nd phase at triple junctions. This in turn decreased the Nd+Pr concentration in thin Nd-rich grain boundary phase, resulting in the lower coercivity.
Flower color patterns have long served as a model for developmental genetics because pigment phenotypes are visually striking, yet generally not required for plant viability, facilitating the genetic ...analysis of color and pattern mutants. The evolution of novel flower colors and patterns has played a key role in the adaptive radiation of flowering plants via their specialized interactions with different pollinator guilds (e.g., bees, butterflies, birds), motivating the search for allelic differences affecting flower color pattern in closely related plant species with different pollinators. We have identified LIGHT AREAS1 (LAR1), encoding an R2R3-MYB transcription factor, as the causal gene underlying the spatial pattern variation of floral anthocyanin pigmentation between two sister species of monkeyflower: the bumblebee-pollinated Mimulus lewisii and the hummingbird-pollinated Mimulus cardinalis. We demonstrated that LAR1 positively regulates FLAVONOL SYNTHASE (FLS), essentially eliminating anthocyanin biosynthesis in the white region (i.e., light areas) around the corolla throat of M. lewisii flowers by diverting dihydroflavonol into flavonol biosynthesis from the anthocyanin pigment pathway. FLS is preferentially expressed in the light areas of the M. lewisii flower, thus prepatterning the corolla. LAR1 expression in M. cardinalis flowers is much lower than in M. lewisii, explaining the unpatterned phenotype and recessive inheritance of the M. cardinalis allele. Furthermore, our gene-expression analysis and genetic mapping results suggest that cis-regulatory change at the LAR1 gene played a critical role in the evolution of different pigmentation patterns between the two species.
A molecular description of the control of floral pigmentation in a multi-species group displaying various flower color patterns is of great interest for understanding the molecular bases of ...phenotypic diversification and pollinator-mediated speciation.
Through transcriptome profiling, mutant analyses and transgenic experiments, we aim to establish a ‘baseline’ floral anthocyanin regulation model in Mimulus lewisii and to examine the different ways of tinkering with this model in generating the diversity of floral anthocyanin patterns in other Mimulus species.
We find one WD40 and one bHLH gene controlling anthocyanin pigmentation in the entire corolla of M. lewisii and two R2R3-MYB genes, PELAN and NEGAN, controlling anthocyanin production in the petal lobe and nectar guide, respectively. The autoregulation of NEGAN might be a critical property to generate anthocyanin spots. Independent losses of PELAN expression (via different mechanisms) explain two natural yellow-flowered populations of M. cardinalis (typically red-flowered). The NEGAN ortholog is the only anthocyanin-activating MYB expressed in the M. guttatus flowers.
The mutant lines and transgenic tools available for M. lewisii will enable gene-by-gene replacement experiments to dissect the genetic and developmental bases of more complex floral color patterns, and to test hypotheses on phenotypic evolution in general.
The microstructure of high-coercivity Nd–Fe–B sintered magnets with a grain size of about 1
μm, which was processed by helium jet milling and the pressless sintering process, was studied by scanning ...electron microscopy, transmission electron microscopy and atom probe tomography. The high coercivity can be attributed to a similar microstructure that is five times smaller than that of conventional sintered magnets. Initial magnetization curves showed a two-step magnetization process, suggesting that the grain boundary phase causes a pinning force.
Epigenetic signaling pathways are implicated in tumorigenesis and therefore histone deacetylases (HDACs) represent novel therapeutic targets for cancers, including multiple myeloma (MM). Although ...non-selective HDAC inhibitors show anti-MM activities, unfavorable side effects limit their clinical efficacy. Isoform- and/or class-selective HDAC inhibition offers the possibility to maintain clinical activity while avoiding adverse events attendant to broad non-selective HDAC inhibition. We have previously reported that HDAC3 inhibition, either by genetic knockdown or selective inhibitor BG45, abrogates MM cell proliferation. Here we show that knockdown of HDAC3, but not HDAC1 or HDAC2, as well as BG45, downregulate expression of DNA methyltransferase 1 (DNMT1) mediating MM cell proliferation. DNMT1 expression is regulated by c-Myc, and HDAC3 inhibition triggers degradation of c-Myc protein. Moreover, HDAC3 inhibition results in hyperacetylation of DNMT1, thereby reducing the stability of DNMT1 protein. Combined inhibition of HDAC3 and DNMT1 with BG45 and DNMT1 inhibitor 5-azacytidine (AZA), respectively, triggers synergistic downregulation of DNMT1, growth inhibition and apoptosis in both MM cell lines and patient MM cells. Efficacy of this combination treatment is confirmed in a murine xenograft MM model. Our results therefore provide the rationale for combination treatment using HDAC3 inhibitor with DNMT1 inhibitor to improve patient outcome in MM.
Microstructures of fine grained Nd–Fe–B sintered magnets that were produced by the pressless process were investigated to understand the origin of the sudden coercivity decrease below a certain grain ...size. The intrinsic coercivity is inversely proportional to ln
D
2 with the highest coercivity of 17
kOe at
D∼4.5
μm, below which the coercivity drops as the grain size decreases. We found that the degradation of the coercivity of the magnet with a grain size of 3
μm was mainly caused by the inhomogeneous distribution of fcc-Nd oxide whose volume fraction increased with respect to the dhcp Nd-rich phase.
Microstructures of Ga-doped ultra-fine-grained (UFG) Nd-Fe-B magnets processed from press-less sintering of He-jet-milled powder and hydrogenation-disproportionation-desorption-recombination (HDDR) ...powder have been investigated to understand the large coercivity difference in the two magnets with nearly the same grain size. While the sintered magnet processed from the jet-milled powder showed a very high coercivity of 2.14 T, the sintered magnet made from HDDR powder showed a low coercivity of only 1.31 T regardless of the similar grain size. Microstructure observations by scanning electron microscopy (SEM) and scanning transmission electron microscope (STEM) combined with energy-dispersive X-ray (EDS) analysis revealed that the Nd-rich grain boundary (GB) phase in the magnet produced from HDDR powder exhibits thickness of 1–2 nm with large variations in their chemical compositions, while the Nd-rich GB phase in the magnet made from He-jet-milled powder displays larger thickness variations (1–7 nm) along with significant increase of nonferromagnetic elements (Nd, Pr, Cu, Ga) in the GB phase after optimal annealing. The possible reasons for these differences in GB phases are discussed based on quantitative microstructure characterization results.
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Abstract
We have developed a system using high-temperature radio frequency superconducting quantum interference device (RF-SQUID) for detecting metallic contaminants in the liquid component of a ...lithium-ion battery. Although we have executed detection experiments using a simulated system without liquid in the past
1
, we have developed a new system to inspect real liquid components. Small cylindrical metallic contaminant samples were fabricated using a gallium-focused ion beam to evaluate the detection performance. Tap water containing the metallic contaminant sample was poured into the tube using a pump, and the magnetic signal of the contaminant matter was detected using the RF-SQUID. Among the tested small metallic contaminant samples, the volume of a minimum detectable metallic contaminant was evaluated to be 2 × 10
4
μm
3
, which corresponded to that of a spherical sample with a diameter of 33 μm and a sensitivity of a signal-to-noise ratio of more than three. Moreover, the dependence of the detected signal strength on the volume of the metallic contaminant samples is discussed here.
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