Leaf Traits Explain the Growth Variation and Nitrogen Response of Eucalyptus urophylla × Eucalyptus grandis and Dalbergia odorifera in Mixed Culture.

Mixed cultivation with legumes may alleviate the nitrogen (N) limitation of monoculture Eucalyptus. However, how leaf functional traits respond to N in mixed cultivation with legumes and how they affect tree growth are unclear. Thus, this study investigated the response of leaf functional traits of Eucalyptus urophylla × Eucalyptus grandis (E. urophylla × E. grandis) and Dalbergia odorifera (D. odorifera) to mixed culture and N application, as well as the regulatory pathways of key traits on seedling growth. In this study, a pot-controlled experiment was set up, and seedling growth indicators, leaf physiology, morphological parameters, and N content were collected and analyzed after 180 days of N application treatment. The results indicated that mixed culture improved the N absorption and photosynthetic rate of E. urophylla × E. grandis, further promoting seedling growth but inhibiting the photosynthetic process of D. odorifera, reducing its growth and biomass. Redundancy analysis and path analysis revealed that leaf nitrogen content, pigment content, and photosynthesis-related physiological indicators were the traits most directly related to seedling growth and biomass accumulation, with the net photosynthetic rate explaining 50.9% and 55.8% of the variation in growth indicators for E. urophylla × E. grandis and D. odorifera, respectively. Additionally, leaf morphological traits are related to the trade-off strategy exhibited by E. urophylla × E. grandis and D. odorifera based on N competition. This study demonstrated that physiological traits related to photosynthesis are reliable predictors of N nutrition and tree growth in mixed stands, while leaf morphological traits reflect the resource trade-off strategies of different tree species.

Stage-specific regulation of DNA methylation by TET enzymes during human cardiac differentiation.

Changes in DNA methylation are associated with normal cardiogenesis, whereas altered methylation patterns can occur in congenital heart disease. Ten-eleven translocation (TET) enzymes oxidize 5-methylcytosine (5mC) and promote locus-specific DNA demethylation. Here, we characterize stage-specific methylation dynamics and the function of TETs during human cardiomyocyte differentiation. Human embryonic stem cells (hESCs) in which all three TET genes are inactivated fail to generate cardiomyocytes (CMs), with altered mesoderm patterning and defective cardiac progenitor specification. Genome-wide methylation analysis shows TET knockout causes promoter hypermethylation of genes encoding WNT inhibitors, leading to hyperactivated WNT signaling and defects in cardiac mesoderm patterning. TET activity is also needed to maintain hypomethylated status and expression of NKX2-5 for subsequent cardiac progenitor specification. Finally, loss of TETs causes a set of cardiac structural genes to fail to be demethylated at the cardiac progenitor stage. Our data demonstrate key roles for TET proteins in controlling methylation dynamics at sequential steps during human cardiac development.

QSER1 protects DNA methylation valleys from de novo methylation.

DNA methylation is essential to mammalian development, and dysregulation can cause serious pathological conditions. Key enzymes responsible for deposition and removal of DNA methylation are known, but how they cooperate to regulate the methylation landscape remains a central question. Using a knockin DNA methylation reporter, we performed a genome-wide CRISPR-Cas9 screen in human embryonic stem cells to discover DNA methylation regulators. The top screen hit was an uncharacterized gene, QSER1, which proved to be a key guardian of bivalent promoters and poised enhancers of developmental genes, especially those residing in DNA methylation valleys (or canyons). We further demonstrate genetic and biochemical interactions of QSER1 and TET1, supporting their cooperation to safeguard transcriptional and developmental programs from DNMT3-mediated de novo methylation.

Tet Proteins Regulate Neutrophil Granulation in Zebrafish through Demethylation of socs3b mRNA.

Tet proteins (Tet1/2/3) convert 5-methylcytosine (5mC) to 5-hydroxy-methylcytosine (5hmC), initiating the process of active demethylation to regulate gene expression. Demethylation has been investigated primarily in the context of DNA, but recently Tet enzymes have also been shown to mediate demethylation of 5mC in RNA as an additional level of epitranscriptomic regulation. We analyzed compound tet2/3 mutant zebrafish and discovered a role for Tet enzymes in the maturation of primitive and definitive neutrophils during granulation. Transcript profiling showed dysregulation of cytokine signaling in tet mutant neutrophils, including upregulation of socs3b. We show that Tet normally demethylates socs3b mRNA during granulation, thereby destabilizing the transcript, leading to its downregulation. Failure of this process leads to accumulation of socs3b mRNA and repression of cytokine signaling at this crucial step of neutrophil maturation. This study provides further evidence for Tets as epitranscriptomic regulatory enzymes and implicates Tet2/3 in regulation of neutrophil maturation.

Epigenetic Regulation of Cardiac Development and Disease through DNA Methylation.

Epigenetic control mechanisms play critical roles in organ development and tissue homeostasis. Increasing evidence suggests that cardiac lineage commitment and cardiovascular disease are tightly regulated by epigenetic mechanisms, controlling changes in DNA methylation, histone modifications, ATP-dependent chromatin remodeling, and expression levels for non-coding RNAs. This review summarizes our current understanding of epigenetic control mechanisms regulating cardiac development and disease, particularly focuses on the function of DNA methylation and demethylation through families of DNA methyltransferases and dioxygenases.

TETs Regulate Proepicardial Cell Migration through Extracellular Matrix Organization during Zebrafish Cardiogenesis.

Ten-eleven translocation (Tet) enzymes (Tet1/2/3) mediate 5-methylcytosine (5mC) hydroxylation, which can facilitate DNA demethylation and thereby impact gene expression. Studied mostly for how mutant isoforms impact cancer, the normal roles for Tet enzymes during organogenesis are largely unknown. By analyzing compound mutant zebrafish, we discovered a requirement for Tet2/3 activity in the embryonic heart for recruitment of epicardial progenitors, associated with development of the atrial-ventricular canal (AVC). Through a combination of methylation, hydroxymethylation, and transcript profiling, the genes encoding the activin A subunit Inhbaa (in endocardium) and Sox9b (in myocardium) were implicated as demethylation targets of Tet2/3 and critical for organization of AVC-localized extracellular matrix (ECM), facilitating migration of epicardial progenitors onto the developing heart tube. This study elucidates essential DNA demethylation modifications that govern gene expression changes during cardiac development with striking temporal and lineage specificities, highlighting complex interactions in multiple cell populations during development of the vertebrate heart.

c-Myb acts in parallel and cooperatively with Cebp1 to regulate neutrophil maturation in zebrafish.

Neutrophils are the key effectors for generating innate immunity in response to pathogenic infection and tissue injury in vertebrates. Dysregulation of neutrophil development and function is known to associate with various human disorders. Yet, the genetic network that orchestrates lineage commitment, differentiation, and maturation of neutrophils remains incompletely defined. Here, we present an in vivo study to delineate the genetic program underlying neutrophil development during zebrafish embryonic myelopoiesis. We show that loss of c-Myb function has no effect on macrophages but severely impairs neutrophil terminal differentiation, resulting in the accumulation of neutrophils with unsegmented nuclei and scant granule. This neutrophilic defect, which resembles the neutrophil-specific granule deficiency (SGD) caused by the mutations in CCAAT/enhancer-binding protein ε (C/EBPε) in humans, is attributed, at least in part, to the downregulation of the granule protein transcription. Likewise, genetic inactivation of Cebp1, the zebrafish functional homolog of mammalian C/EBPε, also leads to a similar SGD-like phenotype in zebrafish. Genetic epistasis and biochemical analysis further reveals that c-Myb and Cebp1 act in parallel and cooperatively to control neutrophil differentiation by directly regulating granule protein gene transcription. Our study indicates that c-MYB is an intrinsic master regulator for neutrophil terminal differentiation and a potential target in SGD patients.

Overlapping Requirements for Tet2 and Tet3 in Normal Development and Hematopoietic Stem Cell Emergence.

The Tet family of methylcytosine dioxygenases (Tet1, Tet2, and Tet3) convert 5-methylcytosine to 5-hydroxymethylcytosine. To date, functional overlap among Tet family members has not been examined systematically in the context of embryonic development. To clarify the potential for overlap among Tet enzymes during development, we mutated the zebrafish orthologs of Tet1, Tet2, and Tet3 and examined single-, double-, and triple-mutant genotypes. Here, we identify Tet2 and Tet3 as the major 5-methylcytosine dioxygenases in the zebrafish embryo and uncover a combined requirement for Tet2 and Tet3 in hematopoietic stem cell (HSC) emergence. We demonstrate that Notch signaling in the hemogenic endothelium is regulated by Tet2/3 prior to HSC emergence and show that restoring expression of the downstream gata2b/scl/runx1 transcriptional network can rescue HSCs in tet2/3 double mutant larvae. Our results reveal essential, overlapping functions for tet genes during embryonic development and uncover a requirement for 5hmC in regulating HSC production.

Maternal or zygotic sphingosine kinase is required to regulate zebrafish cardiogenesis.

BACKGROUND: The sphingosine 1-phosphate (S1P) signaling pathway regulates zebrafish cardiogenesis, and provides a paradigm for how signaling gradients coordinate collective cell migration across tissue layers. It is known that the S1P transporter (Spns2) functions in extra-embryonic YSL to activate G protein-coupled receptor (S1pr2) signaling in endoderm for deposition of positional cues (integrin, fibronectin, etc.). Such cues are recognized by overlying lateral precardiac mesoderm that migrates to the midline and fuses to form the primordial heart tube. However, the source of bio-active S1P is not known. There are multiple receptors and it is not known if there are earlier or even receptor-independent functions for S1P. RESULTS: Because S1P can only be generated by sphingosine kinases, we targeted a mutation to the single kinase gene expressed during early embryogenesis (sphk2). Zygotic mutants survive to adulthood and appear normal, but maternal-zygotic mutant embryos phenocopy null zygotic mutants of spns2 or s1pr2. CONCLUSIONS: The data show that maternally derived sphk2 RNA is fully sufficient to generate an S1P signaling gradient in the YSL that ultimately controls precardiac mesoderm migration during embryogenesis. Furthermore, despite maternal expression of sphk2, there are no obvious developmental functions requiring its activity prior to stimulation of S1pr2 in endoderm.

Evaluation of nurses' knowledge and understanding of obstacles encountered when administering resuscitation medications.

AIM: The aim of the study was to develop and validate an instrument to evaluate nurses' knowledge and to understand the obstacles that they encounter when administering resuscitation medications. BACKGROUND: Insufficient knowledge is a major factor in nurses' drug administration errors. Resuscitation involves situations in which doctors issue oral orders, and is inherently highly stressful. Sufficient knowledge is vital for nurses if they are to respond quickly and accurately when administering resuscitation medications. METHODS: A cross-sectional study was conducted. A questionnaire (20 true-false questions) developed from literature and expert input, and validated by subject experts and one pilot study, was used to evaluate nurses' knowledge of resuscitation medications. Stratified sampling and descriptive statistics were applied. RESULTS: A total of 188 nurses participated. The overall correct answer rate was 70.5% and the greater the nurse's work experience the higher the score. Only 8% of nurses considered themselves to have sufficient knowledge and 73.9% hoped to gain more training about resuscitation medications. The leading obstacle reported was "interruption of the drug administration procedure on resuscitation" (62.8%). Seventeen out of 20 questions achieved a discriminatory power of over 0.36, indicating good to excellent questions. In the study, a total of 16 resuscitation medication errors were reported by the participants, in which the errors involved atropine (five cases), epinephrine (three cases) and others (eight cases). The errors mainly involved misinterpretation of orders, insufficient knowledge and confusing certain drugs for other look-alike drugs. CONCLUSION: Evidence-based results strongly suggest that nurses have insufficient knowledge and could benefit from longer working experience and additional training about resuscitation medications. Further research to validate the instrument is needed and the education of nurses regarding resuscitation medications is recommended.

Medication errors in pediatric nursing: assessment of nurses' knowledge and analysis of the consequences of errors.

AIM: The purposes of this study were (i) to evaluate pediatric nurses' knowledge of pharmacology, and (ii) to analyze known pediatric administration errors. BACKGROUND: Medication errors occur frequently and ubiquitously, but medication errors involving pediatric patients attract special attention for their high incidence and injury rates. METHODS: A cross-sectional study was conducted. A questionnaire with 20 true-false questions regarding pharmacology was used to evaluate nurses' knowledge, and the known pediatric administration errors were reported by nurses. FINDINGS: The overall correct answer rate on the knowledge of pharmacology was 72.9% (n=262). Insufficient knowledge (61.5%) was the leading obstacle nurses encountered when administering medications. Of 141 pediatric medication errors, more than 60% (61.0%) of which were wrong doses, 9.2% of the children involved suffered serious consequences. CONCLUSIONS: Evidence-based results demonstrate that pediatric nurses have insufficient knowledge of pharmacology. Such strategies as providing continuing education and double-checking dosages are suggested.

Hemogenic endothelium specification and hematopoietic stem cell maintenance employ distinct Scl isoforms.

Recent studies have shown that nascent hematopoietic stem cells (HSCs) derive directly from the ventral aortic endothelium (VAE) via endothelial to hematopoietic transition (EHT). However, whether EHT initiates from a random or predetermined subpopulation of VAE, as well as the molecular mechanism underlying this process, remain unclear. We previously reported that different zebrafish stem cell leukemia (scl) isoforms are differentially required for HSC formation in the ventral wall of the dorsal aorta. However, the exact stage at which these isoforms impact HSC development was not defined. Here, using in vivo time-lapse imaging of scl isoform-specific reporter transgenic zebrafish lines, we show that prior to EHT scl-ß is selectively expressed in hemogenic endothelial cells, a unique subset of VAE cells possessing hemogenic potential, whereas scl-α is expressed later in nascent HSCs as they egress from VAE cells. In accordance with their expression, loss-of-function studies coupled with in vivo imaging analysis reveal that scl-ß acts earlier to specify hemogenic endothelium, which is later transformed by runx1 into HSCs. Our results also reveal a previously unexpected role of scl-α in maintaining newly born HSCs in the aorta-gonads-mesonephros. Thus, our data suggest that a defined hemogenic endothelial population preset by scl-ß supports the deterministic emergence of HSCs, and unravel the cellular mechanisms by which scl isoforms regulate HSC development.

SUMO1-activating enzyme subunit 1 is essential for the survival of hematopoietic stem/progenitor cells in zebrafish.

In vertebrates, establishment of the hematopoietic stem/progenitor cell (HSPC) pool involves mobilization of these cells in successive developmental hematopoietic niches. In zebrafish, HSPCs originate from the ventral wall of the dorsal aorta (VDA), the equivalent of the mammalian aorta-gonad-mesonephros (AGM). The HSPCs subsequently migrate to the caudal hematopoietic tissue (CHT) for transitory expansion and differentiation during the larval stage, and they finally colonize the kidney, where hematopoiesis takes place in adult fish. Here, we report the isolation and characterization of a zebrafish mutant, tango(hkz5), which shows defects of definitive hematopoiesis. In tango(hkz5) mutants, HSPCs initiate normally in the AGM and subsequently colonize the CHT. However, definitive hematopoiesis is not sustained in the CHT owing to accelerated apoptosis and diminished proliferation of HSPCs. Positional cloning reveals that tango(hkz5) encodes SUMO1-activating enzyme subunit 1 (Sae1). A chimera generation experiment and biochemistry analysis reveal that sae1 is cell-autonomously required for definitive hematopoiesis and that the tango(hkz5) mutation produces a truncated Sae1 protein (ΔSae1), resulting in systemic reduction of sumoylation. Our findings demonstrate that sae1 is essential for the maintenance of HSPCs during fetal hematopoiesis in zebrafish.

[Medication errors in emergency rooms, intensive care units and pediatric wards].

Medication safety is a major concern worldwide that directly relates to patient care quality and safety. Reducing medication error incidents is a critical medication safety issue. This literature review article summarizes medication error issues related specifically to three hospital units, namely emergency rooms (ERs), intensive care units (ICUs), and pediatric wards. Time constrains, lack of patient history details and the frequent need to use rapid response life-saving medications are key factors behind high ER medication error rates. Patient hypo-responsiveness, complex medication administration and frequent need to use high-alert medications are key factors behind high ICU medication error rates. Medication error in pediatric wards are often linked to errors made by nurses in calculating dosage based on patient body weight. This article summarizes the major types of medication errors reported by these three units in order to increase nurse awareness of medication errors and further encourage nurses to apply proper standard operational procedures to medication administration.