Transcriptional Regulators of Plant Adaptation to Heat Stress.

Heat stress (HS) is becoming an increasingly large problem for food security as global warming progresses. As sessile species, plants have evolved different mechanisms to cope with the disruption of cellular homeostasis, which can impede plant growth and development. Here, we summarize the mechanisms underlying transcriptional regulation mediated by transcription factors, epigenetic regulators, and regulatory RNAs in response to HS. Additionally, cellular activities for adaptation to HS are discussed, including maintenance of protein homeostasis through protein quality control machinery, and autophagy, as well as the regulation of ROS homeostasis via a ROS-scavenging system. Plant cells harmoniously regulate their activities to adapt to unfavorable environments. Lastly, we will discuss perspectives on future studies for improving urban agriculture by increasing crop resilience to HS.

SUPERMAN regulates floral whorl boundaries through control of auxin biosynthesis.

Proper floral patterning, including the number and position of floral organs in most plant species, is tightly controlled by the precise regulation of the persistence and size of floral meristems (FMs). In Arabidopsis, two known feedback pathways, one composed of WUSCHEL (WUS) and CLAVATA3 (CLV3) and the other composed of AGAMOUS (AG) and WUS, spatially and temporally control floral stem cells, respectively. However, mounting evidence suggests that other factors, including phytohormones, are also involved in floral meristem regulation. Here, we show that the boundary gene SUPERMAN (SUP) bridges floral organogenesis and floral meristem determinacy in another pathway that involves auxin signaling. SUP interacts with components of polycomb repressive complex 2 (PRC2) and fine-tunes local auxin signaling by negatively regulating the expression of the auxin biosynthesis genes YUCCA1/4 (YUC1/4). In sup mutants, derepressed local YUC1/4 activity elevates auxin levels at the boundary between whorls 3 and 4, which leads to an increase in the number and the prolonged maintenance of floral stem cells, and consequently an increase in the number of reproductive organs. Our work presents a new floral meristem regulatory mechanism, in which SUP, a boundary gene, coordinates floral organogenesis and floral meristem size through fine-tuning auxin biosynthesis.

Range of Normal Liver Stiffness and Factors Associated With Increased Stiffness Measurements in Apparently Healthy Individuals.

BACKGROUND & AIMS: Transient elastography (TE) is a noninvasive technique used to measure liver stiffness to estimate the severity of fibrosis. The range of liver stiffness measurements (LSMs) in healthy individuals is unclear. We performed a systematic review to determine the range of LSMs, examined by TE, in healthy individuals and individuals who are susceptible to fibrosis. METHODS: We collected data from 16,082 individuals, in 26 cohorts, identified from systematic searches of Embase, Ovid MEDLINE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews for studies of liver stiffness measurements. Studies analyzed included apparently healthy adults (normal levels of liver enzymes, low-risk alcohol use patterns, and negative for markers of viral hepatitis). The presence of diabetes, hypertension, dyslipidemia, or steatosis, based on ultrasound examination, was known for most participants. We performed a meta-analysis of data from individual participants. The cohort was divided into 4 groups; participants with a body mass index <30 kg/m2 were examined with the medium probe and those with a body mass index ≥30 kg/m2 were examined with the extra-large probe. Linear regression models were conducted after adjusting for potential confounding factors of LSMs. We performed several sensitivity analyses. RESULTS: We established LSM ranges for healthy individuals measured with both probes-these did not change significantly in sensitivity analyses of individuals with platelets ≥150,000/mm3 and levels of alanine aminotransferase ≤33 IU/L in men or ≤25 IU/L in women. In multivariate analysis, factors that modified LSMs with statistical significance included diabetes, dyslipidemia, waist circumference, level of aspartate aminotransferase, and systolic blood pressure at examination time. Significant increases in LSMs were associated with the metabolic syndrome in individuals examined by either probe. Diabetes in obese individuals increased the risk of LSMs in the range associated with advanced fibrosis. CONCLUSIONS: In a systematic review and meta-analysis of data from individual participants, we established a comprehensive set of LSM ranges, measured by TE in large cohorts of healthy individuals and persons susceptible to hepatic fibrosis. Regression analyses identified factors associated with increased LSMs obtained by TE with the medium and extra-large probes.

When to stop: an update on molecular mechanisms of floral meristem termination.

Flowers have fascinated humans for millennia, not only because of their beauty, but also because they give rise to fruits, from which most agricultural products are derived. In most angiosperms, the number and position of floral organs are morphologically and genetically defined, and their development is tightly controlled by complex regulatory networks to ensure reproductive success. How flower development is temporally initiated and spatially maintained has been widely researched. As the flower develops, the balance between proliferation and differentiation dynamically shifts towards organogenesis and termination of floral stem cell maintenance. In this review, we focus on recent findings that further reveal the intricate molecular mechanisms for precise timing of floral meristem termination.

Arabidopsis MRG domain proteins bridge two histone modifications to elevate expression of flowering genes.

Trimethylation of lysine 36 of histone H3 (H3K36me3) is found to be associated with various transcription events. In Arabidopsis, the H3K36me3 level peaks in the first half of coding regions, which is in contrast to the 3'-end enrichment in animals. The MRG15 family proteins function as 'reader' proteins by binding to H3K36me3 to control alternative splicing or prevent spurious intragenic transcription in animals. Here, we demonstrate that two closely related Arabidopsis homologues (MRG1 and MRG2) are localised to the euchromatin and redundantly ensure the increased transcriptional levels of two flowering time genes with opposing functions, FLOWERING LOCUS C and FLOWERING LOCUS T (FT). MRG2 directly binds to the FT locus and elevates the expression in an H3K36me3-dependent manner. MRG1/2 binds to H3K36me3 with their chromodomain and interact with the histone H4-specific acetyltransferases (HAM1 and HAM2) to achieve a high expression level through active histone acetylation at the promoter and 5' regions of target loci. Together, this study presents a mechanistic link between H3K36me3 and histone H4 acetylation. Our data also indicate that the biological functions of MRG1/2 have diversified from their animal homologues during evolution, yet they still maintain their conserved H3K36me3-binding molecular function.

Atypical culture-negative skull base osteomyelitis masquerading as advanced nasopharyngeal carcinoma.

Skull base osteomyelitis typically arises as a complication of otogenic or sinonasal infections in immunocompromised patients. A much rarer entity, atypical skull base osteomyelitis is not associated with an obvious infective source. Atypical and culture-negative skull base osteomyelitis is even rarer and hampers diagnosis, as its clinical presentation is remarkably similar to skull base neoplasms. We report a case of extensive skull base osteomyelitis with orbital apex syndrome and multiple lower cranial nerve palsies which initially masqueraded as possible advanced nasopharyngeal carcinoma. Extensive investigations and consult with an infectious diseases specialist aided in elucidation of the correct diagnosis. Through this article, we emphasize that skull base osteomyelitis must be considered in the setting of headache, cranial neuropathies, elevated inflammatory markers and abnormal imaging findings. Early tissue sampling for histology, stainings and cultures and prompt appropriate treatment may prevent or arrest further complications.

Co-ordination of Flower Development Through Epigenetic Regulation in Two Model Species: Rice and Arabidopsis.

Angiosperms produce flowers for reproduction. Flower development is a multistep developmental process, beginning with the initiation of the floral meristems, followed by floral meristem identity specification and maintenance, organ primordia initiation, floral organ identity specification, floral stem cell termination and finally floral organ maturation. During flower development, each of a large number of genes is expressed in a spatiotemporally regulated manner. Underlying these molecular and phenotypic events are various genetic and epigenetic pathways, consisting of diverse transcription factors, chromatin-remodeling factors and signaling molecules. Over the past 30 years, genetic, biochemical and genomic assays have revealed the underlying genetic frameworks that control flower development. Here, we will review the transcriptional regulation of flower development in two model species: Arabidopsis thaliana and rice (Oryza sativa). We focus on epigenetic regulation that functions to co-ordinate transcription pathways in flower development.

Texture-based classification of liver fibrosis using MRI.

PURPOSE: To investigate the ability of texture analysis of MRI images to stage liver fibrosis. Current noninvasive approaches for detecting liver fibrosis have limitations and cannot yet routinely replace biopsy for diagnosing significant fibrosis. MATERIALS AND METHODS: Forty-nine patients with a range of liver diseases and biopsy-confirmed fibrosis were enrolled in the study. For texture analysis all patients were scanned with a T2 -weighted, high-resolution, spin echo sequence and Haralick texture features applied. The area under the receiver operating characteristics curve (AUROC) was used to assess the diagnostic performance of the texture analysis. RESULTS: The best mean AUROC achieved for separating mild from severe fibrosis was 0.81. The inclusion of age, liver fat and liver R2 variables into the generalized linear model improved AUROC values for all comparisons, with the F0 versus F1-4 comparison the highest (0.91). CONCLUSION: Our results suggest that a combination of MRI measures, that include selected texture features from T2 -weighted images, may be a useful tool for excluding fibrosis in patients with liver disease. However, texture analysis of MRI performs only modestly when applied to the classification of patients in the mild and intermediate fibrosis stages.

Orbital compartment syndrome during endoscopic drainage of subperiosteal orbital abscess.

BACKGROUND: Orbital compartment syndrome is a rare ocular emergency requiring immediate intervention to prevent vision loss. It can arise due to a variety of causes including trauma, neoplasms and retrobulbar hemorrhage during endoscopic sinus surgery. Lateral canthotomy and inferior cantholysis is a well-known therapeutic procedure to rapidly relieve raised intraocular pressures. CASE REPORT: We report a case of a subperiosteal orbital abscess due to acute maxillary sinusitis that underwent endoscopic drainage. Intraoperatively, he developed raised intraocular pressure following irrigation of the maxillary sinus and manual pressure on the malar abscess, necessitating emergent lateral canthotomy and inferior cantholysis. CONCLUSION: To our knowledge, this is the first reported case of orbital compartment syndrome following sinonasal irrigation and malar pressure in the English literature. This case will serve as a reminder to the sinus surgeon of the potential danger of transmitted pressure from the paranasal sinus or malar soft tissue into the orbital compartment.

Omalizumab therapy for refractory allergic fungal rhinosinusitis patients with moderate or severe asthma.

PURPOSE: 1. To assess the efficacy of omalizumab therapy in improving sinonasal outcomes in refractory allergic fungal rhinosinusitis (AFRS) patients with moderate or severe asthma. 2. To determine if omalizumab therapy reduces the usage of corticosteroids or antifungal therapy in AFRS patients DESIGN: The clinical charts of patients with AFRS with moderate or severe asthma who received at least three subcutaneous injections of omalizumab therapy between 1st January 2012 and 1st May 2014 were retrospectively reviewed. These patients had undergone bilateral functional endoscopic sinus surgery (FESS) and failed adjunct medical treatments (oral or topical corticosteroids and/or antifungal therapy) prior to omalizumab therapy. RESULTS: Seven patients met the inclusion criteria and were included in this study. The mean age of the patients was 48.14. The average number of subcutaneous omalizumab injections was 7.57 (range 6-11) with a mean dosage of 287mg (range 225-375mg). The mean pre-omalizumab treatment Sino-Nasal Outcome Test-22 (SNOT-22) score was 52.14 while the mean post-omalizumab treatment SNOT-22 score was 35.86 (31% improvement). The mean pre-omalizumab therapy Phillpott-Javer endoscopic score (over the last one year before omalizumab therapy) was 36 while the mean post-omalizumab therapy endoscopic score (from the last clinic visit) was 14 (61% improvement). Omalizumab therapy reduced the dependence of AFRS patients on corticosteroid and antifungal treatments. CONCLUSION: Omalizumab therapy can be considered as a potential adjunct for the treatment for patients with refractory AFRS with moderate or severe asthma. However, larger prospective studies to confirm the findings of this study will be required.

Analysis of the intrahepatic ductular reaction and progenitor cell responses in hepatitis C virus recurrence after liver transplantation.

Fibrosis in livers with hepatitis C virus (HCV) recurrence after liver transplantation (LT) can be rapidly progressive, and the mechanisms underlying this process are poorly understood. In livers with HCV infections in the non-LT setting, there is a significant relationship between the development of structures known as the ductular reaction (DR), hepatic progenitor cells (HPCs), and fibrosis. This study characterizes the DR, HPCs, and fibrosis associated with HCV recurrence after LT. Immunohistochemistry and confocal microscopy were used to characterize the DR, HPC, and fibrosis in liver biopsy specimens. Key findings were confirmed in a separate, independent cohort. The initial characterization cohort had 194 biopsy samples from 105 individuals with HCV recurrence after LT. The immunophenotype, morphology, and location of the DR were consistent with an HPC origin. The DR correlated with intrahepatic fibrosis (rs = 0.529, P < 0.001) and the number of activated hepatic stellate cells (HSCs; rs = 0.446, P < 0.001). There was an early occurrence of hepatocyte replicative arrest as well as increased hepatocyte proliferation that correlated with the DR (rs = 0.295, P < 0.001). Replicative arrest preceded hepatocyte proliferation in early-stage injury. Hepatocyte proliferation decreased with advanced fibrosis; in contrast, the extent of the DR and the number of activated HSCs continued to increase. In the second cohort of 37 individuals, the DR and the number of HPCs similarly correlated with fibrosis and inflammation after LT. In conclusion, this is the first characterization of the DR in HCV-associated liver injury after LT. There was a significant correlation between the DR and the development of progressive fibrosis in HCV recurrence. These results suggest a pivotal role for both the DR and the HPC responses in the aggressive fibrosis seen with HCV recurrence after LT.

Disruption of hemochromatosis protein and transferrin receptor 2 causes iron-induced liver injury in mice.

UNLABELLED: Mutations in hemochromatosis protein (HFE) or transferrin receptor 2 (TFR2) cause hereditary hemochromatosis (HH) by impeding production of the liver iron-regulatory hormone, hepcidin (HAMP). This study examined the effects of disruption of Hfe or Tfr2, either alone or together, on liver iron loading and injury in mouse models of HH. Iron status was determined in Hfe knockout (Hfe(-/-)), Tfr2 Y245X mutant (Tfr2(mut)), and double-mutant (Hfe(-/-) ×Tfr2(mut) ) mice by measuring plasma and liver iron levels. Plasma alanine transaminase (ALT) activity, liver histology, and collagen deposition were evaluated to assess liver injury. Hepatic oxidative stress was assessed by measuring superoxide dismutase (SOD) activity and F(2)-isoprostane levels. Gene expression was measured by real-time polymerase chain reaction. Hfe(-/-) ×Tfr2(mut) mice had elevated hepatic iron with a periportal distribution and increased plasma iron, transferrin saturation, and non-transferrin-bound iron, compared with Hfe(-/-), Tfr2(mut), and wild-type (WT) mice. Hamp1 expression was reduced to 40% (Hfe(-/-) and Tfr2(mut) ) and 1% (Hfe(-/-) ×Tfr2(mut)) of WT values. Hfe(-/-) ×Tfr2(mut) mice had elevated plasma ALT activity and mild hepatic inflammation with scattered aggregates of infiltrating inflammatory cluster of differentiation 45 (CD45)-positive cells. Increased hepatic hydoxyproline levels as well as Sirius red and Masson's Trichrome staining demonstrated advanced portal collagen deposition. Hfe(-/-) and Tfr2(mut) mice had less hepatic inflammation and collagen deposition. Liver F(2) -isoprostane levels were elevated, and copper/zinc and manganese SOD activities decreased in Hfe(-/-) ×Tfr2(mut), Tfr2(mut), and Hfe(-/-) mice, compared with WT mice. CONCLUSION: Disruption of both Hfe and Tfr2 caused more severe hepatic iron overload with more advanced lipid peroxidation, inflammation, and portal fibrosis than was observed with the disruption of either gene alone. The Hfe(-/-) ×Tfr2(mut) mouse model of iron-induced liver injury reflects the liver injury phenotype observed in human HH.

Misexpression Approaches for the Manipulation of Flower Development.

The generation of dominant gain-of-function mutants through activation tagging is a forward genetic approach that can be applied to study the mechanisms of flower development, complementing the screening of loss-of-function mutants. In addition, the functions of genes of interest can be further analyzed through reverse genetics. A commonly used method is gene overexpression, where ectopic expression can result in an opposite phenotype to that caused by a loss-of-function mutation. When overexpression is detrimental, the misexpression of a gene using tissue-specific promoters can be useful to study spatial-specific function. As flower development is a multistep process, it can be advantageous to control gene expression, or its protein product activity, in a temporal and/or spatial manner. This has been made possible through several inducible promoter systems as well as inducible proteins by constructing chimeric fusions between the ligand-binding domain of the glucocorticoid receptor (GR) and the protein of interest. The recently introduced CRISPR-Cas9-based platform provides a new way of bioengineering transcriptional regulators in plants. By fusing a catalytically inactive dCas9 with functional activation or repression domains, the CRISPR-Cas9 module can achieve transcriptional activation or repression of endogenous genes. All these methods allow us to genetically manipulate gene expression during flower development. In this chapter, we describe methods to produce the expression constructs, method of screening, and more general applications of the techniques.

Histone Demethylases JMJ30 and JMJ32 Modulate the Speed of Vernalization Through the Activation of FLOWERING LOCUS C in Arabidopsis thaliana.

Vernalization is the promotion of flowering after prolonged exposure to cold. In Arabidopsis thaliana, vernalization induces epigenetic silencing of the floral repressor gene FLOWERING LOCUS C (FLC). Among the repressive epigenetic marks, the trimethylation of lysine 27 on histone H3 proteins (H3K27me3) is a critical contributor to the epigenetic silencing of FLC. The deposition of H3K27me3 is mediated by Polycomb Repressive Complex 2 (PRC2). Conversely, the elimination of H3K27me3 is mediated by histone demethylases, Jumonji-C domain-containing protein JMJ30 and its homolog JMJ32. However, the role of JMJ30 and JMJ32 in vernalization is largely unknown. In this study, we found that cold treatment dramatically reduced the expression levels of JMJ30 and did not reduce those of JMJ32. Next, by using the genetic approach, we found that the flowering of jmj30 jmj32 was accelerated under moderate vernalized conditions. Under moderate vernalized conditions, the silencing of FLC occurred more quickly in jmj30 jmj32 than in the wild type. These results suggested that the histone demethylases JMJ30 and JMJ32 brake vernalization through the activation of FLC. Our study suggested that PRC2 and Jumonji histone demethylases act in an opposing manner to regulate flowering time via epigenetic modifications.

Natural history and management of HFE-hemochromatosis.

Advances in our knowledge of hereditary hemochromatosis (HH) over the past 150 years have revealed new insights into this common genetic disorder. Meticulous family and HLA association studies followed ultimately by cloning of the HFE gene have dramatically changed our understanding of the natural history and manifestations of HH. Cross-sectional studies demonstrated that HH had a highly variable clinical and biochemical penetrance in susceptible individuals of northern European descent. "State-of-the-art" large longitudinal population studies have accurately defined the natural history. We now recognize that HH is not as discreet an entity as previously thought because genetic and environmental modifiers of disease penetrance are increasingly identified as influencing the clinical course of HH. While phlebotomy remains the cornerstone of therapy, our diagnostic approach has been refined to incorporate new biochemical, genetic, and noninvasive methods that complement more traditional approaches. This review aims to encapsulate this new knowledge in a framework that addresses commonly raised issues relating to the current natural history, diagnosis, and management of HH patients.

Identification of a Devernalization Inducer by Chemical Screening Approaches in Arabidopsis thaliana.

Vernalization is the promotion of flowering after prolonged exposure to cold. In Arabidopsis thaliana, vernalization induces epigenetic silencing of the floral repressor gene FLOWERING LOCUS C (FLC). The repressive epigenetic mark trimethylation of lysine 27 on histone H3 proteins (H3K27me3) is a critical contributor to the epigenetic silencing of FLC. Interestingly, the deposited H3K27me3 in the FLC locus can be erased by short-term high-temperature treatment. This is referred to as devernalization. In this study, we identified a novel chemical compound, 4-Isoxazolecarboxylic acid, 3,5-dimethyl-2-(4-fluorophenyl)-4-isoxazole carboxylic acid 1-methyl-2-oxoethyl ester named as DEVERNALIZER01 (DVR01), which induces devernalization in Arabidopsis seedlings, by an FLC-luciferase reporter-based high-throughput screening assay. DVR01 decreased the amount of H3K27me3 in the FLC locus in vernalized plants, resulting in the upregulation of FLC in the whole plant, including the vasculature and meristem, where FLC represses floral induction genes. We also showed that a 2-week treatment with DVR01 reverted plants with a vernalized status back to a fully non-vernalized status. Collectively, this study provides a novel structure of DVR01, which modulates devernalization via demethylation of H3K27me3 in the FLC locus.

H3K27me3 demethylases alter HSP22 and HSP17.6C expression in response to recurring heat in Arabidopsis.

Acclimation to high temperature increases plants' tolerance of subsequent lethal high temperatures. Although epigenetic regulation of plant gene expression is well studied, how plants maintain a memory of environmental changes over time remains unclear. Here, we show that JUMONJI (JMJ) proteins, demethylases involved in histone H3 lysine 27 trimethylation (H3K27me3), are necessary for Arabidopsis thaliana heat acclimation. Acclimation induces sustained H3K27me3 demethylation at HEAT SHOCK PROTEIN22 (HSP22) and HSP17.6C loci by JMJs, poising the HSP genes for subsequent activation. Upon sensing heat after a 3-day interval, JMJs directly reactivate these HSP genes. Finally, jmj mutants fail to maintain heat memory under fluctuating field temperature conditions. Our findings of an epigenetic memory mechanism involving histone demethylases may have implications for environmental adaptation of field plants.

Phenotypic expression of hereditary hemochromatosis: what have we learned from the population studies?

Profound advances in our knowledge of hereditary hemochromatosis (HH) during the past 150 years have resulted in two distinct "iron ages": the pre-HFE gene era and the post-HFE gene era. During these periods, family studies, HLA association studies, and ultimately HFE gene studies in various populations informed us of the genotypic prevalence as well as the clinical and biochemical penetrance of HH. We learned that HH has a highly variable clinical penetrance in susceptible individuals of Northern European ancestry. Further, we now recognize that the natural history of HH is not as discrete as previously believed, because genetic and environmental modifiers of disease penetrance are increasingly identified as influencing the clinical expression of HH.

Predicting iron overload in hyperferritinemia.

BACKGROUND & AIMS: Hyperferritinemia is a common abnormality. This study determined the prevalence of hepatic iron overload in subjects of northern European origin with hyperferritinemia. METHODS: Fifty-two consecutive subjects referred for evaluation of suspected iron overload (serum ferritin level >350 microg/L) were divided into 3 groups: group 1, increased transferrin saturation and no significant hemochromatosis gene product (HFE) mutations (N = 17); group 2, increased transferrin saturation and C282Y homozygosity or C282Y/H63D compound heterozygosity (N = 22); and group 3, normal transferrin saturation and no significant HFE mutations (N = 13). All subjects underwent magnetic resonance R2 relaxometry for quantitation of hepatic iron concentration (HIC). RESULTS: The HIC was significantly higher in group 2 subjects (123 +/- 22 micromol/g) compared with groups 1 and 3 subjects (39 +/- 4 and 36 +/- 5 micromol/g, respectively) (P < .01). Nine of 22 subjects in group 2 had an increase of their HIC to greater than 3 times the upper limit of normal compared with none in the other 2 groups (P < .01). CONCLUSIONS: An increase of HIC to greater than 3 times the upper limit of normal is highly unlikely in hyperferritinemic subjects who do not have HFE-related hereditary hemochromatosis or causes of secondary iron overload.

Hemorrhagic extrahepatic recurrence of hepatocellular carcinoma: A case report.

The recurrence of hepatocellular carcinoma (HCC) can mainly be divided into two phases or types: the intrahepatic recurrence (IHR) and the extrahepatic recurrence (EHR). Generally speaking, the EHR is usually referenced as being the less common of the two types or categories. In a post-hemihepatectomy patient with routine surveillance at 6 months, it was noted that the patient appeared to have an elevated alpha-fetoprotein, and also complained of vague lower abdominal pain. The accompanying computed tomography scan revealed a 6 cm-sized heterogeneous mass located at the pelvis region. Next, during a laparotomy for resection, the tumor was found to be bleeding from the omental deposition. In conclusion, a high index of suspicion and early surgical intervention can help in detecting possible bleeding extrahepatic recurrence in the background of a patient with history of HCC.