Dual function of Arabidopsis A TAF1 in abiotic and biotic stress responses

NAC 家庭基因编码涉及多样的生物过程的植物特定的抄写因素。在这研究， Arabidopsis NAC 基因 ATAF1 被发现被干旱导致，高咸度， abscisic 酸(骆驼毛的织物) ，甲基 jasmonate，机械伤害，并且 Botrytis cinerea 感染。ATAF1 的重要正式就职在受到干旱或高咸度的骆驼毛的织物缺乏的变异的 aba2 被发现，揭示表示的骆驼毛的织物无关的机制。Arabidopsis ATAF1-overexpression 线显示了许多改变的显型，包括侏儒症和短主要的根。而且，在 vivo，实验显示 ATAF1 是真正的管理者 modulating 植物对许多不能生活的压力和 necrotrophic 病原体感染的回答。在 Arabidopsis 的 ATAF1 的 Overexpression 增加了植物敏感到骆驼毛的织物，盐，和氧化压力。特别， ATAF1 overexpression 种，然而并非异种排队显示出的显著地提高的植物忍耐到干旱。另外， ATAF1 overexpression 提高了植物危险性到 necrotrophic 病原体 B。cinerea，但是没改变 P 的无毒害或剧毒的紧张引起的疾病症状。syringae pv 西红柿 DC3000。转基因的植物 overexpressing ATAF1 对氧化应力过分敏感，建议反应的氧中介可能与响应病原体和不能生活的压力的调停 ATAF1 的发信号有关。

Segmental Translocation Contributed to the Origin of the Brassica S-locus

Self-incompatibility(SI),which has recurred during the evolution of plants,is one of the most important cross-pollination mating systems.Three S-loci have been reported in Brassicaceae,namely,Arabidopsis lyrata(Al),Brassica(Br),and Leavenworthia alabamica(La)S-loci.Here,through multi-genomic comparative analysis of 20 species,we revealed that the most ancient S-locus was formed prior to the divergence of Brassicaceae lineage I and II.Itwas retained and inherited by Arabidopsis,as the Al S-locus in Brassicaceae lineage I.Furthermore,we found that the Br S-locus,which has been widely used in the breeding of Brassica crops to generate hybrid seeds,was formed through segmental translocation(ST)in the hexaploid ancestor of Brassica in Brassicaceae lineage II.The Br S-locus was evolved through a ST from one of the triplicated ancestral S-locus paralogs in the Brassica hexaploidy ancestor,while the other two S-locus paralogs were lost.Together with the previous discovery that the La S-locus was formed through a secondary origin in Brassicaceae lineage I,we conclude the monophyletic origin of Al and Br S-loci and clarify the evolutionary route of S-loci in the Brassicaceae family.Our findings will contribute to evolutionary studies and breeding applications of the S-locus in Brassicaceae.

Identification and characterization of human hematopoietic mesoderm

The embryonic mesoderm comprises heterogeneous cell subpopulations with distinct lineage biases.It is unclear whether a bias for the human hematopoietic lineage emerges at this early developmental stage.In this study,we integrated single-cell transcriptomic analyses of human mesoderm cells from embryonic stem cells and embryos,enabling us to identify and define the molecular features of human hematopoietic mesoderm(HM)cells biased towards hematopoietic lineages.We discovered that BMP4 plays an essential role in HM specification and can serve as a marker for HM cells.Mechanistically,BMP4 acts as a downstream target of HDAC1,which modulates the expression of BMP4 by deacetylating its enhancer.Inhibition of HDAC significantly enhances HM specification and promotes subsequent hematopoietic cell differentiation.In conclusion,our study identifies human HM cells and describes new mechanisms for human hematopoietic development.

Chemical screening reveals Ronidazole is a superior prodrug to Metronidazole for nitroreductase-induced cell ablation system in zebrafish larvae

The Metronidazole(MTZ)/nitroreductase(NTR)-mediated cell ablation system is the most commonly used chemical-genetic cell ablation method in zebrafish. This system can specifically ablate target cells under spatial and temporal control. The MTZ/NTR system has become a widely used cell ablation system in biological, developmental, and functional studies. However, the inadequate cell-ablation ability of some cell types and the side effects of high concentration MTZ impede extensive applications of the MTZ/NTR system. In the present study, the US drug collection library was searched to extend the NTR system. Six MTZ analogs were found, and the cell-ablation ability of these analogs was tested in zebrafish larvae. The results revealed that two of the NTR substrates, Furazolidone and Ronidazole, ablated target cells more efficiently than MTZ at lower concentrations. Furthermore, the working concentration of Ronidazole, but not Furazolidone and MTZ, did not affect axonal bridge formation during spinal cord regeneration. Our results,taken together, indicate that Ronidazole is a superior prodrug to MTZ for the NTR system, especially for the study of neuron regeneration in zebrafish larvae.

Comparison Analysis of Transcripts from the Halophyte Thellungiella halophila

The Brassicaceae family halophyte Thellungiella halophila has a high salinity tolerance and serves as a valuable halophytic genetic model plant with experimental convenience similar to Arabidopsis thaliana. A cDNA library of Thellungiella was generated from salt-treated seedlings including rosettes and roots. More than 1000 randomly selected clones were sequenced and 946 expressed sequence tags （ESTs） were generated. The accession numbers of our EST data are available online in the GenBank database from EC598928 to EC599965. In total 679 unique clusters were assembled, and 632 （93%） had BLASTX hits in the nr databases and 7% are Thellungiella unique. According to the Gene Ontology （GO） hierarchy, 385 of 679 unigenes were categorized. Compared with public Arabidopsis microarray data, our results provide more potential salt tolerance genes in Thellungiella. These results will provide a broader coverage into Thellungiella transcriptome and benefit the discovery of salt tolerance related genes.

Large-Scale Forward Genetic Screening Analysis of Development of Hematopoiesis in Zebrafish

Zebrafish is a powerful model for the investigation of hematopoiesis.In order to isolate novel mutants with hematopoietic defects, large-scale mutagenesis screening of zebrafish was performed.By scoring specific hematopoietic markers,52 mutants were identified and then classified into four types based on specific phenotypic traits.Each mutant represented a putative mutation of a gene regulating the relevant aspect of hematopoiesis,including early macrophage development,early granulopoiesis,embryonic myelopoiesis,and definitive erythropoiesis/lymphopoiesis.Our method should be applicable for other types of genetic screening in zebrafish.In addition,further study of the mutants we identified may help to unveil the molecular basis of hematopoiesis.

The synergistic role of Pu.1 and Fms in zebrafish osteoclast-reducing osteopetrosis and possible therapeutic strategies

Osteoclasts are bone resorption cells of myeloid origin. Osteoclast defects can lead to osteopetrosis, a genetic disorder characterized by bone sclerosis for which there is no effective drug treatment. It is known that Pu.1 and Fms are key regulators in myelopoiesis, and their defects in mice can lead to reduced osteoclast numbers and consequent osteopetrosis. Yet how Pu.1 and Fms genetically interact in the development of osteoclasts and the pathogenesis of osteopetrosis is still unclear. Here, we characterized pu.1^(G242) D;fms^(j4e1) double-deficient zebrafish, which exhibited a greater deficiency of functional osteoclasts and displayed more severe osteopetrotic symptoms than the pu.1^(G242) Dor fms^(j4e1) single mutants, suggesting a synergistic function of Pu.1 and Fms in the regulation of osteoclast development. We further demonstrated that Pu.1 plays a dominant role in osteoclastogenesis, whereas Fms plays a dominant role in osteoclast maturation. Importantly, treatment with the drug retinoic acid significantly relieved the different degrees of osteopetrosis symptoms in these models by increasing the number of functional osteoclasts. Thus, we report the development of valuable animal models of osteopetrosis, and our results shed light on drug development for antiosteopetrosis therapy.

Zebrafish Cdh5 negatively regulates mobilization of aorta-gonad-mesonephros-derived hematopoietic stem cells

Establishment of a hematopoietic stem cell（HSC）pool depends on the appropriate formation,maturation and mobilization of HSCs in vertebrates.In mice,the aorta-gonad-mesonephros（AGM）is a prominent site for the formation of definitive HSCs from endothelial cells,although the placenta and yolk sac also give rise to HSCs（Mikkola and Orkin,2006;Chen et al.,2009）.After formation,AGM-derived HSCs migrate to the fetal liver（FL）,and ultimately to the bone marrow （BM）, two definitive hematopoietic organs （Cumano and Godin, 2007）.

Cebpa is essential for the embryonic myeloid progenitor and neutrophil maintenance in zebrafish

In vertebrates, myeloid cells arise from multiple waves of development： the first or embryonic wave of myelopoiesis initiates early from non-hematopoietic stem cell（HSC） precursors and gives rise to myeloid cells transiently during early development; whereas the second or adult wave of myelopoiesis emerges later from HSCs and produces myeloid cells continually during fetal and adult life. In the past decades, a great deal has been learnt about the development of myeloid cells from adult myelopoiesis, yet the genetic network governing embryonic myelopoiesis remains poorly defined. In this report, we present an in vivo study to delineate the role of Cebpa during zebrafish embryonic myelopoiesis. We show that embryonic myelopoiesis in cebpa-deficient zebrafish mutants initiates properly but fails to produce macrophages and neutrophils. The lack of macrophages and neutrophils in the mutants is largely attributed to the cell cycle arrest of embryonic myeloid progenitors, resulting in the impairment of their maintenance and subsequent differentiation. We further show that Cebpa, perhaps acting cooperatively with Runx1, plays a critical role in embryonic neutrophil maintenance. Our findings reveal a new role of Cebpa in embryonic myelopoiesis.

Slc20a1b is essential for hematopoietic stem/progenitor cell expansion in zebrafish

Hematopoietic stem and progenitor cells(HSPCs)are able to self-renew and can give rise to all blood lineages throughout their lifetime,yet the mechanisms regulating HSPC development have yet to be discovered.In this study,we characterized a hematopoiesis defective zebrafish mutant line named smu07,which was obtained from our previous forward genetic screening,and found the HSPC expansion deficiency in the mutant.Positional cloning identified that slc20a1b,which encodes a sodium phosphate cotransporter,contributed to the smu07 blood phenotype.Further analysis demonstrated that mutation of slc20a1b affects HSPC expansion through cell cycle arrest at G2/M phases in a cell-autonomous manner.Our study shows that slc20a1b is a vital regulator for HSPC proliferation in zebrafish early hematopoiesis and provides valuable insights into HSPC development.

Zebrafish for thrombocytopoiesis-and hemostasis-related researches and disorders

Platelets play vital roles in hemostasis,inflammation,and vascular biology.Platelets are also active participants in the immune responses.As vertebrates,zebrafish have a highly conserved hematopoietic system in the developmental,cellular,functional,biochemical,and genetic levels with mammals.Thrombocytes in zebrafish are functional homologs of mammalian platelets.Here,we summarized thrombocyte development,function,and related research techniques in zebrafish,and reviewed available zebrafish models of platelet-associated disorders,including congenital amegakaryocytic thrombocytopenia,inherited thrombocytopenia,essential thrombocythemia,and blood coagulation disorders such as gray platelet syndrome.These elegant zebrafish models and methods are crucial for understanding the molecular and genetic mechanisms of thrombocyte development and function,and provide deep insights into related human disease pathophysiology and drug development.