LEAFY and APETALA1 down-regulate ZINC FINGER PROTEIN 1 and 8 to release their repression on class B and C floral homeotic genes.

Organ initiation from the shoot apical meristem first gives rise to leaves during vegetative development and then flowers during reproductive development. LEAFY (LFY) is activated after floral induction and together with other factors promotes the floral program. LFY functions redundantly with APETALA1 (AP1) to activate the class B genes APETALA3 (AP3) and PISTILLATA (PI), the class C gene AGAMOUS (AG), and the class E gene SEPALLATA3, which leads to the specification of stamens and carpels, the reproductive organs of flowers. Molecular and genetic networks that control the activation of AP3, PI, and AG in flowers have been well studied; however, much less is known about how these genes are repressed in leaves and how their repression is lifted in flowers. Here, we showed that two genes encoding Arabidopsis C2H2 ZINC FINGER PROTEIN (ZFP) transcription factors, ZP1 and ZFP8, act redundantly to directly repress AP3, PI, and AG in leaves. After LFY and AP1 are activated in floral meristems, they down-regulate ZP1 and ZFP8 directly to lift the repression on AP3, PI, and AG. Our results reveal a mechanism for how floral homeotic genes are repressed and derepressed before and after floral induction.

Evolution of High-Index Facets Pt Nanocrystals Induced by N-Defective Sites in the Integrated Electrode for Enhanced Methanol Oxidation.

Highly efficient and durable Pt electrocatalysts are the key to boost the performance of fuel cells. The high-index facets (HIF) Pt nanocrystals are regarded as excellent catalytic activity and stability catalysts. However, nucleation, growth and evolution of high-index facets Pt nanocrystals induced by defective sites is still a challenge. In this work, tetrahexahedron (THH) and hexactahedron (HOH) Pt nanocrystals are synthesized, which are loaded on the nitrogen-doped reduced graphene oxide (N-rGO) support of the integrated electrodes by the square wave pulse method. Experimental investigations and density functional theory (DFT) calculations are conducted to analyze the growth and evolution mechanism of HIF Pt nanocrystals on the graphene-derived carbon supports. It shows that the H adsorption on the N-rGO/CFP support can induce evolution of Pt nanocrystals. Moreover, the N-defective sites on the surface of N-rGO can lead to a slower growth of Pt nanocrystals than that on the surface of reduced graphene oxide (rGO). Pt/N-rGO/CFP (20 min) shows the highest specific activity in methanol oxidation, which is 1.5 times higher than that of commercial Pt/C. This research paves the way on the design and synthesis of HIF Pt nanocrystal using graphene-derived carbon materials as substrates in the future.

Aintegumenta And Redundant Aintegumenta-Like6 Are Required For Bract Outgrowth In Arabidopsis.

Plants consist of fundamental units of growth called phytomers (leaf or bract, axillary bud, node, and internode), which are repeated and modified throughout shoot development to give plants plasticity for survival and adaptation. One phytomer modification is the suppression or outgrowth of bracts, the leaves subtending the flowers. The floral meristem identity regulator LEAFY (LFY) and the organ boundary genes BLADE-ON-PETIOLE1 (BOP1) and BOP2, have been shown to suppress bract development in Arabidopsis, as mutations in these genes result in bract outgrowth. However, much less is known about the mechanisms that promote bract outgrowth in Arabidopsis mutants such as these. Further understanding of this mechanism may provide a potential tool for modifying leaf development. Here, we showed that the MADS-box genes SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), FRUITFUL (FUL), and AGAMOUS-LIKE24 (AGL24) play more important roles than BOP1/2 and LFY in bract suppression, and that AINTEGUMENTA (ANT) and the partially redundant AINTEGUMENTA-LIKE6 (AIL6) are necessary for bract outgrowth in these mutant backgrounds. We also showed that misexpression of AIL6 alone is sufficient for bract outgrowth. Our data reveal a mechanism for bract suppression and outgrowth and provide insight into phytomer plasticity.

Induction of potent antitumor immunity by intradermal DNA injection using a novel needle-free pyro-drive jet injector.

The current success of mRNA vaccines against COVID-19 has highlighted the effectiveness of mRNA and DNA vaccinations. Recently, we demonstrated that a novel needle-free pyro-drive jet injector (PJI) effectively delivers plasmid DNA into the skin, resulting in protein expression higher than that achieved with a needle syringe. Here, we used ovalbumin (OVA) as a model antigen to investigate the potential of the PJI for vaccination against cancers. Intradermal injection of OVA-expression plasmid DNA into mice using the PJI, but not a needle syringe, rapidly and greatly augmented OVA-specific CD8+ T-cell expansion in lymph node cells. Increased mRNA expression of both interferon-γ and interleukin-4 and an enhanced proliferative response of OVA-specific CD8+ T cells, with fewer CD4+ T cells, were also observed. OVA-specific in vivo killing of the target cells and OVA-specific antibody production of both the IgG2a and IgG1 antibody subclasses were greatly augmented. Intradermal injection of OVA-expression plasmid DNA using the PJI showed stronger prophylactic and therapeutic effects against the progression of transplantable OVA-expressing E.G7-OVA tumor cells. Even compared with the most frequently used adjuvants, complete Freund's adjuvant and aluminum hydroxide with OVA protein, intradermal injection of OVA-expression plasmid DNA using the PJI showed a stronger CTL-dependent prophylactic effect. These results suggest that the novel needle-free PJI is a promising tool for DNA vaccination, inducing both a prophylactic and a therapeutic effect against cancers, because of prompt and strong generation of OVA-specific CTLs and subsequently enhanced production of both the IgG2a and IgG1 antibody subclasses.

Target-allele-specific probe single-base extension (TASP-SBE): a novel MALDI-TOF-MS strategy for multi-variants analysis and its application in simultaneous detection of α-/ß-thalassemia mutations.

Single-nucleotide variants (SNVs) and copy number variations (CNVs) are the most common genomic variations that cause phenotypic diversity and genetic disorders. MALDI-TOF-MS is a rapid and cost-effective technique for multi-variant genotyping, but it is challenging to efficiently detect CNVs and clustered SNVs, especially to simultaneously detect CNVs and SNVs in one reaction. Herein, a novel strategy termed Target-Allele-Specific Probe Single-Base Extension (TASP-SBE) was devised to efficiently detect CNVs and clustered SNVs with MALDI-TOF-MS. By comprehensive use of traditional SBE and TASP-SBE strategies, a MALDI-TOF-MS assay was also developed to simultaneously detect 28 α-/ß-thalassemia mutations in a single reaction system, including 4 α-thalassemia deletions, 3 HBA and 21 HBB SNVs. The results showed that all 28 mutations were sensitively identified, and the CNVs of HBA/HBB genes were also accurately analyzed based on the ratio of peak height (RPH) between the target allele and reference gene. The double-blind evaluation results of 989 thalassemia carrier samples showed a 100% concordance of this assay with other methods. In conclusion, a one-tube MALDI-TOF-MS assay was developed to simultaneously genotype 28 thalassemia mutations. This novel TASP-SBE was also verified a practicable strategy for the detection of CNVs and clustered SNVs, providing a feasible approach for multi-variants analysis with MALDI-TOF-MS technique.

SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 9 and 13 repress BLADE-ON-PETIOLE 1 and 2 directly to promote adult leaf morphology in Arabidopsis.

The juvenile-to-adult phase transition during vegetative development is a critical decision point in a plant's life cycle. This transition is mediated by a decline in levels of miR156/157 and an increase in the activities of its direct targets, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) proteins. In Arabidopsis, the juvenile-to-adult transition is characterized by an increase in the length to width ratio of the leaf blade (a change in the distal region of a leaf), but what mediates this change in lamina shape is not known. Here, we show that ectopic expression of SPL9 and SPL13 produces enlarged and elongated leaves, resembling leaves from the blade-on-petiole1 (bop1) bop2 double mutant. The expression of BOP1/BOP2 is down-regulated in successive leaves, correlating with the amount of miR156 and antagonistic to the expression of SPL9 and SPL13 in leaves. SPL9 and SPL13 bind to the promoters of BOP1/BOP2 directly to repress their expression, resulting in delayed establishment of proliferative regions in leaves, which promotes more blade outgrowth (the distal region of a leaf) and suppresses petiole development (the proximal region of a leaf). Our results reveal a mechanism for leaf development along the proximal-distal axis, a heteroblastic character between juvenile leaves and adult leaves.

PICKLE associates with histone deacetylase 9 to mediate vegetative phase change in Arabidopsis.

The juvenile-to-adult vegetative phase change in flowering plants is mediated by a decrease in miR156 levels. Downregulation of MIR156A/MIR156C, the two major sources of miR156, is accompanied by a decrease in acetylation of histone 3 lysine 27 (H3K27ac) and an increase in trimethylation of H3K27 (H3K27me3) at MIR156A/MIR156C in Arabidopsis. Here, we show that histone deacetylase 9 (HDA9) is recruited to MIR156A/MIR156C during the juvenile phase and associates with the CHD3 chromatin remodeler PICKLE (PKL) to erase H3K27ac at MIR156A/MIR156C. H2Aub and H3K27me3 become enriched at MIR156A/MIR156C, and the recruitment of Polycomb Repressive Complex 2 (PRC2) to MIR156A/MIR156C is partially dependent on the activities of PKL and HDA9. Our results suggest that PKL associates with histone deacetylases to erase H3K27ac and promote PRC1 and PRC2 activities to mediate vegetative phase change and maintain plants in the adult phase after the phase transition.

Low light intensity delays vegetative phase change.

Plants that develop under low light (LL) intensity often display a phenotype known as the "shade tolerance syndrome (STS)". This syndrome is similar to the phenotype of plants in the juvenile phase of shoot development, but the basis for this similarity is unknown. We tested the hypothesis that the STS is regulated by the same mechanism that regulates the juvenile vegetative phase by examining the effect of LL on rosette development in Arabidopsis (Arabidopsis thaliana). We found that LL prolonged the juvenile vegetative phase and that this was associated with an increase in the expression of the master regulators of vegetative phase change, miR156 and miR157, and a decrease in the expression of their SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE (SPL) targets. Exogenous sucrose partially corrected the effect of LL on seedling development and miR156 expression. Our results suggest that the response of Arabidopsis to LL is mediated by an increase in miR156/miR157 expression and by factors that repress SPL gene expression independently of miR156/miR157, and is caused in part by a decrease in carbohydrate production. The effect of LL on vegetative phase change does not require the photoreceptors and transcription factors responsible for the shade avoidance syndrome, implying that light intensity and light quality regulate rosette development through different pathways.

H2A.Z promotes the transcription of MIR156A and MIR156C in Arabidopsis by facilitating the deposition of H3K4me3.

Vegetative phase change in Arabidopsis thaliana is mediated by a decrease in the level of MIR156A and MIR156C, resulting in an increase in the expression of their targets, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes. Changes in chromatin structure are required for the downregulation of MIR156A and MIR156C, but whether chromatin structure contributes to their initial elevated expression is unknown. We found that mutations in components of the SWR1 complex (ARP6, SEF) and in genes encoding H2A.Z (HTA9 and HTA11) reduce the expression of MIR156A and MIR156C, and accelerate vegetative phase change, indicating that H2A.Z promotes juvenile vegetative identity. However, arp6 and sef did not accelerate the temporal decline in miR156, and the downregulation of MIR156A and MIR156C was not accompanied by significant change in the level of H2A.Z at these loci. We conclude that H2A.Z contributes to the high expression of MIR156A/MIR156C early in shoot development, but does not regulate the timing of vegetative phase change. Our results also suggest that H2A.Z promotes the expression of MIR156A/MIR156C by facilitating the deposition of H3K4me3, rather than by decreasing nucleosome occupancy.

Ionic liquid-derived Fe, N, S, F multiple heteroatom-doped carbon materials for enhanced oxygen reduction reaction.

Heteroatoms doped carbon catalysts have been intensively studied to take the place of Platinum based catalysts for oxygen reduction reaction (ORR) because of their ideal catalytic activity. Herein, the microporous-mesoporous carbon material catalysts doped with Fe, N, S and F were synthesized through a plain one-pot pyrolysis method with ionic liquid 1-butyl-3-methyli-midazolium bis((trifluoromethyl)sulfonyl)imide ([Bmim][TF2N]) and melamine as precursors. Electrochemical analysis shows that the ORR activity and stability of the obtained catalysts are obviously better than Pt/C under alkaline condition. Meanwhile, the catalysts show similar ORR activity and much better durability in 0.1 M HClO4comparing to Pt/C. Moreover, the tolerance of methanol in both basic and acid solutions is greatly better than Pt/C. The high activity is ascribed to the large specific surface area, porous structure and the synergistic effect between S, F, pyridine N, graphite N and Fe-Nx. The high stability possibly comes from the appropriate graphitization and the carbon-coating effect. The strategy proposed here has the advantages of facile, low cost, high efficiency and easy large-scale production, which provides new ideas for the preparation of high-performance Fe-N-C electrocatalysts.

Threshold-dependent repression of SPL gene expression by miR156/miR157 controls vegetative phase change in Arabidopsis thaliana.

Vegetative phase change is regulated by a decrease in the abundance of the miRNAs, miR156 and miR157, and the resulting increase in the expression of their targets, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. To determine how miR156/miR157 specify the quantitative and qualitative changes in leaf morphology that occur during vegetative phase change, we measured their abundance in successive leaves and characterized the phenotype of mutations in different MIR156 and MIR157 genes. miR156/miR157 decline rapidly between leaf 1&2 and leaf 3 and decrease more slowly after this point. The amount of miR156/miR157 in leaves 1&2 greatly exceeds the threshold required to specify their identity. Subsequent leaves have relatively low levels of miR156/miR157 and are sensitive to small changes in their abundance. In these later-formed leaves, the amount of miR156/miR157 is close to the threshold required to specify juvenile vs. adult identity; a relatively small decrease in the abundance of miR156/157 in these leaves produces a disproportionately large increase in SPL proteins and a significant change in leaf morphology. miR157 is more abundant than miR156 but has a smaller effect on shoot morphology and SPL gene expression than miR156. This may be attributable to the inefficiency with which miR157 is loaded onto AGO1, as well as to the presence of an extra nucleotide at the 5' end of miR157 that is mis-paired in the miR157:SPL13 duplex. miR156 represses different targets by different mechanisms: it regulates SPL9 by a combination of transcript cleavage and translational repression and regulates SPL13 primarily by translational repression. Our results offer a molecular explanation for the changes in leaf morphology that occur during shoot development in Arabidopsis and provide new insights into the mechanism by which miR156 and miR157 regulate gene expression.

Post-Embryonic Phase Transitions Mediated by Polycomb Repressive Complexes in Plants.

Correct timing of developmental phase transitions is critical for the survival and fitness of plants. Developmental phase transitions in plants are partially promoted by controlling relevant genes into active or repressive status. Polycomb Repressive Complex1 (PRC1) and PRC2, originally identified in Drosophila, are essential in initiating and/or maintaining genes in repressive status to mediate developmental phase transitions. Our review summarizes mechanisms in which the embryo-to-seedling transition, the juvenile-to-adult transition, and vegetative-to-reproductive transition in plants are mediated by PRC1 and PRC2, and suggests that PRC1 could act either before or after PRC2, or that they could function independently of each other. Details of the exact components of PRC1 and PRC2 in each developmental phase transitions and how they are recruited or removed will need to be addressed in the future.

Characterization of a Novel 71.8 kb α0-Thalassemia Deletion and Subsequent Summary of a Practical Procedure for Thalassemia Molecular Diagnosis.

Thalassemia is the most common monogenic disorder around the world. Based on the principle of genotype-phenotype correlation, identification of thalassemia mutations is the essential prerequisite for clinical diagnosis and management. Because only common mutations are routinely detected, the identification of rare or undetermined mutations is a challenge for clinical laboratories. Herein, a proband presenting with inconsistent phenotype-genotype correlation after routine molecular screening was investigated by multiplex ligation-dependent probe amplification (MLPA), targeted-next generation sequencing (targeted-NGS), gap-polymerase chain reaction (gap-PCR) and Sanger sequencing. Eventually, a novel 71.8 kb deletion (- -71.8) was identified and characterized, which included HBZ (ζ), HBA2 (α2), and HBA1 (α1) genes and was causing α0-thalassemia (α0-thal). Furthermore, we summarized a practical procedure based on accumulated experience in studies and clinical practice, which can be a guide for molecular screening and clinical diagnosis of thalassemia, especially for identification of undetermined or novel mutations.

Juvenile Leaves or Adult Leaves: Determinants for Vegetative Phase Change in Flowering Plants.

Vegetative leaves in Arabidopsis are classified as either juvenile leaves or adult leaves based on their specific traits, such as leaf shape and the presence of abaxial trichomes. The timing of the juvenile-to-adult phase transition during vegetative development, called the vegetative phase change, is a critical decision for plants, as this transition is associated with crop yield, stress responses, and immune responses. Juvenile leaves are characterized by high levels of miR156/157, and adult leaves are characterized by high levels of miR156/157 targets, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. The discovery of this miR156/157-SPL module provided a critical tool for elucidating the complex regulation of the juvenile-to-adult phase transition in plants. In this review, we discuss how the traits of juvenile leaves and adult leaves are determined by the miR156/157-SPL module and how different factors, including embryonic regulators, sugar, meristem regulators, hormones, and epigenetic proteins are involved in controlling the juvenile-to-adult phase transition, focusing on recent insights into vegetative phase change. We also highlight outstanding questions in the field that need further investigation. Understanding how vegetative phase change is regulated would provide a basis for manipulating agricultural traits under various conditions.

Epigenetic Regulation of Vegetative Phase Change in Arabidopsis.

Vegetative phase change in flowering plants is regulated by a decrease in the level of miR156. The molecular mechanism of this temporally regulated decrease in miR156 expression is still unknown. Most of the miR156 in Arabidopsis thaliana shoots is produced by MIR156A and MIR156C. We found that the downregulation of these genes during vegetative phase change is associated with an increase in their level of histone H3 lysine 27 trimethylation (H3K27me3) and requires this chromatin modification. The increase in H3K27me3 at MIR156A/MIR156C is associated with an increase in the binding of PRC2 to these genes and is mediated redundantly by the E(z) homologs SWINGER and CURLY LEAF. The CHD3 chromatin remodeler PICKLE (PKL) promotes the addition of H3K27me3 to MIR156A/MIR156C but is not responsible for the temporal increase in this chromatin mark. PKL is bound to the promoters of MIR156A/MIR156C, where it promotes low levels of H3K27ac early in shoot development and stabilizes the nucleosome at the +1 position. These results suggest a molecular mechanism for the initiation and maintenance of vegetative phase change in plants.

Regulation of myelopoiesis by proinflammatory cytokines in infectious diseases.

Hematopoiesis is hierarchically orchestrated by a very small population of hematopoietic stem cells (HSCs) that reside in the bone-marrow niche and are tightly regulated to maintain homeostatic blood production. HSCs are predominantly quiescent, but they enter the cell cycle in response to inflammatory signals evoked by severe systemic infection or injury. Thus, hematopoietic stem and progenitor cells (HSPCs) can be activated by pathogen recognition receptors and proinflammatory cytokines to induce emergency myelopoiesis during infection. This emergency myelopoiesis counterbalances the loss of cells and generates lineage-restricted hematopoietic progenitors, eventually replenishing mature myeloid cells to control the infection. Controlled generation of such signals effectively augments host defense, but dysregulated stimulation by these signals is harmful to HSPCs. Such hematopoietic failure often results in blood disorders including chronic inflammatory diseases and hematological malignancies. Recently, we found that interleukin (IL)-27, one of the IL-6/IL-12 family cytokines, has a unique ability to directly act on HSCs and promote their expansion and differentiation into myeloid progenitors. This process resulted in enhanced production of neutrophils by emergency myelopoiesis during the blood-stage mouse malaria infection. In this review, we summarize recent advances in the regulation of myelopoiesis by proinflammatory cytokines including type I and II interferons, IL-6, IL-27, granulocyte colony-stimulating factor, macrophage colony-stimulating factor, and IL-1 in infectious diseases.

Controllable Synthesis and Characterization of AuPd Nanowire Networks with High Electrocatalytic Performance.

A simple and efficient method is proposed for the synthesis of bimetallic AuPd nanowire networks (NWs) with tunable compositions by using KBr as a structure-directing agent and NaBH4 as a reducing agent. TEM, XRD and XPS results show that the AuPd NWs have a unique one-dimensional network structure. Electrochemical tests indicate that the AuPd NWs catalysts have excellent electrocatalytic activity and durability for methanol oxidation due to the special one-dimensional nanostructure and many structural defects at the junction. The Au1Pd1 NWs show better catalytic activity, which is 2.03 times higher than that of the commercial Pd/C catalyst.

Developmental Functions of miR156-Regulated SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) Genes in Arabidopsis thaliana.

Correct developmental timing is essential for plant fitness and reproductive success. Two important transitions in shoot development-the juvenile-to-adult vegetative transition and the vegetative-to-reproductive transition-are mediated by a group of genes targeted by miR156, SQUAMOSA PROMOTER BINDING PROTEIN (SBP) genes. To determine the developmental functions of these genes in Arabidopsis thaliana, we characterized their expression patterns, and their gain-of-function and loss-of-function phenotypes. Our results reveal that SBP-LIKE (SPL) genes in Arabidopsis can be divided into three functionally distinct groups: 1) SPL2, SPL9, SPL10, SPL11, SPL13 and SPL15 contribute to both the juvenile-to-adult vegetative transition and the vegetative-to-reproductive transition, with SPL9, SP13 and SPL15 being more important for these processes than SPL2, SPL10 and SPL11; 2) SPL3, SPL4 and SPL5 do not play a major role in vegetative phase change or floral induction, but promote the floral meristem identity transition; 3) SPL6 does not have a major function in shoot morphogenesis, but may be important for certain physiological processes. We also found that miR156-regulated SPL genes repress adventitious root development, providing an explanation for the observation that the capacity for adventitious root production declines as the shoot ages. miR156 is expressed at very high levels in young seedlings, and declines in abundance as the shoot develops. It completely blocks the expression of its SPL targets in the first two leaves of the rosette, and represses these genes to different degrees at later stages of development, primarily by promoting their translational repression. These results provide a framework for future studies of this multifunctional family of transcription factors, and offer new insights into the role of miR156 in Arabidopsis development.

[Genetic and phenotypic analysis of a rare case with homozygous Chinese Gγ (Aγδß)0-thal deletion].

OBJECTIVE: To analyze the genotype of a patient suspected for thalassemia through a series of experiments. METHODS: Conventional methods for detecting common thalassemia mutations was used in conjunction with multiplex ligation-dependent probe amplification (MLPA) in order to determine the genotype of the patient. Corresponding primers were designed for developing a Gap-PCR system for detecting rare type mutations. RESULTS: The patient was identified as a homozygote for Chinese Gγ(Aγδß)0-thal deletion, with clinical manifestations tending to be intermediate or severe based on the hematological characteristics. A Gap-PCR system has been developed for detecting the above mutation with accuracy and rapidity. CONCLUSION: The Chinese Gγ(Aγδß)0-thal is prevalent in southern China, and caution should be taken to avoid misdiagnosis. The Gap-PCR system for detecting Chinese Gγ(Aγδß)0-thal is suitable for extended applications for its simplicity and rapidity.

Metal-Organic Frameworks as Micromotors with Tunable Engines and Brakes.

Herein, we report that UiO-type (UiO = University of Oslo) metal-organic frameworks (MOFs) can be transformed into self-propelled micromotors by employing several different metal-based propulsion systems. Incorporation of a bipyridine ligand into the UiO-67 lattice transforms the crystallites, upon metalation, into single-site, metal-based catalytic "engines" to power the micromotors with chemical fuel. The "engine performance" (i.e., propulsion) of the single-site powered micromotors has been tuned by the choice of the metal ion utilized. In addition, a chemical "braking" system was achieved by adding chelating agents capable of sequestering the metal ion engines and thereby suppressing the catalytic activity, with different chelators displaying different deceleration capacities. These results demonstrate that MOFs can be powered by various engines and halted by different brakes, resulting in a high degree of motion design and control at the nanoscale.