A tomato chloroplast-targeted DnaJ protein, SlDnaJ20 maintains the stability of photosystem I/II under chilling stress.

DnaJ proteins are key molecular chaperones that act as a part of the stress response to stabilize plant proteins, thereby maintaining protein homeostasis under stressful conditions. Herein we used transgenic plants to explore the role of the tomato (Solanum lycopersicum) SlDnaJ20 chloroplast DnaJ protein in to the resistance of these proteins to cold. When chilled, transgenic plants exhibited superior cold resistance, with reduced growth inhibition and cellular damage and increased fresh mass and chlorophyll content relative to control. These transgenic plants further exhibited increased Fv/Fm, P700 oxidation, φRo, and δRo relative to control plants under chilling conditions. Under these same cold conditions, these transgenic plants also exhibited higher levels of core proteins in the photosystem I (PSI) and II (PSII) complexes (PsaA and PsaB; D1 and D2) relative to control wild-type plants. Together these results suggested that the overexpression of SlDnaJ20 is sufficient to maintain PSI and PSII complex stability and to alleviate associated photoinhibition of these complexes, thereby increasing transgenic plant resistance to cold stress.

Campylobacter jejuni Cytolethal Distending Toxin Induces GSDME-Dependent Pyroptosis in Colonic Epithelial Cells.

Background: Cytolethal distending toxin (CDT) is a critical virulence factor of Campylobacter jejuni, and it induces cell death and regulates inflammation response in human epithelial cells. Pyroptosis is an inflammatory form of programmed cell death (PCD), but whether it is involved in CDT-mediated cytotoxicity remains elusive. Aims: This study explores the role and mechanism of pyroptosis in CDT-mediated cytotoxicity. Methods: HCT116 and FHC cell lines were treated with CDT. Cell Counting Kit-8 (CCK-8) assay was used to detect cell viability. Western blotting was used to measure the expression of related proteins in the pathway, and cell morphology observation, annexin V/propidium iodide (PI) staining and lactate dehydrogenase (LDH) release assay were performed to evaluate the occurrence of pyroptosis. Result: Our results show that C. jejuni CDT effectively induces pyroptosis in a dose- and time- dependent manner in human colonic epithelial cells owing to its DNase activity. Specific pyroptotic features including large bubbles emerging from plasma membrane and LDH release were observed upon CDT treatment. Moreover, CDT-induced pyroptosis involves the caspase-9/caspase-3 axis, which is followed by gasdermin E (GSDME) cleavage rather than gasdermin D (GSDMD). N-acetyl cysteine (NAC), a reactive oxygen species (ROS) inhibitor, attenuates the activation of caspase-9/3, the cleavage of GSDME and pyroptotic characteristic, therefore demonstrating ROS initiates pyroptotic signaling. Conclusions: We first clarify a molecular mechanism that CDT induces pyroptosis via ROS/caspase-9/caspase-3/GSDME signaling. These findings provide a new insight on understanding of CDT-induced pathogenesis at the molecular level.

Right atrial papillary fibroelastoma arising from the Chiari network detected by echocardiography: a case report and literature review.

PURPOSE: To improve our understanding of cardiac papillary fibroelastomaand provide evidence for its treatment and prognosis. MATERIALS AND METHODS: We report a 54-year-old Chinese male who was hospitalized for a 14-day headache with a previous vertebral aneurysm history. A right atrial mass arising from the Chiari network was detected by echocardiography and complete tumor resection was performed finally. Pathologic findings confirmed the diagnosis of cardiac papillary fibroelastoma. The recovery of the patient was uneventful and follow-up echocardiographic examination revealed no recurrence of the tumor. RESULTS: Transthoracic echocardiography revealed a mobile, sessile mass in the right atrium without obstructing the orifice of the tricuspid valve. The subsequent transesophageal echocardiography confirmed the presence of a 1.56cm × 1.24cm mobile, sessile, irregular mass arising from the Chiari network (Fig. 1) and showed no evidence of patent foramen ovale. CONCLUSIONS: Early recognition and surgical excision is essential for patients with cardiac papillary fibroelastoma.

Auto-classification of biomass through characterization of their pyrolysis behaviors using thermogravimetric analysis with support vector machine algorithm: case study for tobacco.

BACKGROUND: During the biomass-to-bio-oil conversion process, many studies focus on studying the association between biomass and bio-products using near-infrared spectra (NIR) and chemical analysis methods. However, the characterization of biomass pyrolysis behaviors using thermogravimetric analysis (TGA) with support vector machine (SVM) algorithm has not been reported. In this study, tobacco was chosen as the object for biomass, because the cigarette smoke (including water, tar, and gases) released by tobacco pyrolysis reactions decides the sensory quality, which is similar to biomass as a renewable resource through the pyrolysis process. RESULTS: SVM algorithm has been employed to automatically classify the planting area and growing position of tobacco leaves using thermogravimetric analysis data as the information source for the first time. Eighty-eight single-grade tobacco samples belonging to four grades and eight categories were split into the training, validation, and blind testing sets. Our model showed excellent performances in both the training and validation set as well as in the blind test, with accuracy over 91.67%. Throughout the whole dataset of 88 samples, our model not only provides precise results on the planting area of tobacco leave, but also accurately distinguishes the major grades among the upper, lower, and middle positions. The error only occurs in the classification of subgrades of the middle position. CONCLUSIONS: From the case study of tobacco, our results validated the feasibility of using TGA with SVM algorithm as an objective and fast method for auto-classification of tobacco planting area and growing position. In view of the high similarity between tobacco and other biomasses in the compositions and pyrolysis behaviors, this new protocol, which couples the TGA data with SVM algorithm, can potentially be extrapolated to the auto-classification of other biomass types.

Type A2 BTB Members Decrease the ABA Response during Seed Germination by Affecting the Stability of SnRK2.3 in Arabidopsis.

The Arabidopsis genome comprises eighty genes encoding BTB (broad-complex, tramtrack, and bric-a-brac) family proteins that are characterized with the BTB domain and that potentially serve as substrate adaptors for cullin-based E3-ligases. In addition to the BTB domain, most BTB proteins also contain various other interaction motifs that probably act as target recognition elements. Here, we report three members of the BTB-A2 subfamily that distinctly only contain the BTB domain, BTB-A2.1, BTB-A2.2, and BTB-A2.3, that negatively regulates abscisic acid (ABA) signaling in Arabidopsis. BTB-A2.1, BTB-A2.2, and BTB-A2.3 encoded cytoplasm- and nucleus-localized proteins and displayed highly overlapping expression patterns in Arabidopsis tissues. Disruption of these three genes, but not single or double mutants, resulted in a decrease in ABA-induced inhibition of seed germination. Further analyses demonstrated the expression levels of these three genes were up-regulated by ABA, and their mutation increased ABA signalling. Importantly, protein-protein interaction assays showed that these three BTB-A2 proteins physically interacted with SnRK2.3. Moreover, biochemical and genetic assays indicated that BTB-A2.1, BTB-A2.2, and BTB-A2.3 decreased the stability of SnRK2.3 and attenuated the SnRK2.3 responsible for the ABA hypersensitive phenotype of seed germination. This report thus reveals that BTB-A2s serve as negative regulators for balancing the intensity of ABA signaling during seed germination.

Choline transporter-like 1 (CTL1) positively regulates apical hook development in etiolated Arabidopsis seedlings.

Ethylene is a gaseous phytohormone that is perceived by two-component histidine kinase-type receptors. Recent studies identified choline transporter-like 1 (CTL1) essential for Arabidopsis growth and development, including apical hook development in the etiolated seedlings. Here, we report that CTL1 contributes to apical hook development by enhancing ethylene response. The expression of CTL1 was highly correlated with the intensity of ethylene response and was enriched in the apical hook, cotyledon tip and hypocotyl. Genetic analysis showed that the dark-grown ctl1 mutant displayed a defect in ethylene-induced apical hook development as compared with the wild type. Accordingly, the expression of ethylene signaling reporter EBS::GUS in ctl1 mutant was greatly reduced in leaves, apical hook, hypocotyl and root, suggesting that the disruption of CTL1 impairs the ethylene signaling. Furthermore, protein-protein interaction assays demonstrated that CTL1 may interact with ethylene receptors, including ETR1, ETR2, ERS1, ERS2. Importantly, the abundance of CTL1 was diminished when ETR1 was disrupted upon ethylene response. Taken together, our results suggest that CTL1 functions as a positive regulator in ethylene signaling which in turn contributes to apical hook development of etiolated plant seedlings.

A tomato transcription factor, SlDREB3 enhances the tolerance to chilling in transgenic tomato.

The dehydration response factor (DREB) transcription factor (TF) family can function in response to multiple cues around environment in plants. Nevertheless, the functions of dehydration response factor (DREB protein) in plant cold tolerance, especially in tomatoes (Solanum lycopersicum), have been rarely studied. In this study, the functions of tomato DREB TF (SlDREB3) in cold resistance were studied using transgenic tomatoes. The level of transcripts revealed that SlDREB3 was triggered by H2O2 and 4 °C treatments, indicating that SlDREB3 participates in response to cold stress in plants. SlDREB3-overexpressing plants exhibited high fresh mass, chlorophyll content, Fv/Fm, and O2-evolving activity; low membrane damage; and reactive oxygen species accumulation under chilling stress. Furthermore, the high expression levels of late embryogenesis-abundant genes SlLEA9 and SlLEA26 were detected in transgenic plants in response to cold stress. These findings revealed that SlDREB3 overexpression improved the tolerance to cold stress in transgenic plants possibly by upregulating SlLEAs expression.

Novel DnaJ Protein Facilitates Thermotolerance of Transgenic Tomatoes.

DnaJ proteins, which are molecular chaperones that are widely present in plants, can respond to various environmental stresses. At present, the function of DnaJ proteins was studied in many plant species, but only a few studies were conducted in tomato. Here, we examined the functions of a novel tomato (Solanum lycopersicum) DnaJ protein (SlDnaJ20) in heat tolerance using sense and antisense transgenic tomatoes. Transient conversion assays of Arabidopsis protoplasts showed that SlDnaJ20 was targeted to chloroplasts. Expression analysis showed that SlDnaJ20 expression was induced by chilling, NaCl, polyethylene glycol, and H2O2, especially via heat stress. Under heat stress, sense plants showed higher fresh weights, chlorophyll content, fluorescence (Fv/Fm), and D1 protein levels, and a lower accumulation of reactive oxygen species (ROS) than antisense plants. These results suggest that SlDnaJ20 overexpression can reduce the photoinhibition of photosystem II (PSII) by relieving ROS accumulation. Moreover, higher expression levels of HsfA1 and HsfB1 were observed under heat stress in sense plants, indicating that SlDnaJ20 overexpression contributes to HSF expression. The yeast two-hybrid system proved that SlDnaJ20 can interact with the chloroplast heat-shock protein 70. Our results indicate that SlDnaJ20 overexpression enhances the thermotolerance of transgenic tomatoes, whereas suppression of SlDnaJ20 increases the heat sensitivity of transgenic tomatoes.

Association of CYP17A1 gene -34T/C polymorphism with polycystic ovary syndrome in Han Chinese population.

PURPOSE: To investigate the influence of the cytochrome P450 17α (CYP17A1) gene -34T/C polymorphism in the pathogenesis of polycystic ovary syndrome (PCOS) in Han Chinese population. METHODS: Three-hundred eighteen patients with PCOS and 306 controls were recruited and the CYP17A1 -34T/C polymorphism was genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Furthermore, the relationship of CYP17A1 -34T/C polymorphism and clinical feature parameters of PCOS patients was also analyzed. RESULTS: The prevalence rates of CYP17A1 genotype TT, TC and CC were 49.69%, 43.71% and 6.6% in the case group and those were 44.77%, 46.08% and 9.15% in the control group. The frequencies of CYP17A1 T and C alleles were 71.54% and 28.46% in the case group, and those were 67.81% and 32.19% in the control group. Neither the genotypic nor the allelic distribution was significantly different between the cases and controls. However, the PCOS patients with the genotype of CC had significantly higher total testosterone levels and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) than those with the genotype of TT or TC. CONCLUSIONS: The CYP17A1 gene -34T/C polymorphism might not be directly correlated with the PCOS, but might influence PCOS via the association of testosterone level and the HOMA-IR.

Group 5 LEA protein, ZmLEA5C, enhance tolerance to osmotic and low temperature stresses in transgenic tobacco and yeast.

Group 5 LEA (Late Embryogenesis Abundant) proteins contain a significantly higher proportion of hydrophobic residues but lack significant signature motifs or consensus sequences. This group is considered as an atypical group of LEA proteins. Up to now, there is little known about group 5C LEA proteins in maize. Here, we identified a novel group 5C LEA protein from maize. The accumulation of transcripts demonstrated that ZmLEA5C displayed similar induced characteristics in leaves and roots. Transcription of ZmLEA5C could be induced by low temperature, osmotic and oxidative stress and some signaling molecules, such as abscisic acid (ABA), salicylic acid (SA) and methyl jasmonate (MeJA). However, transcription of ZmLEA5C was significantly inhibited by high salinity. Further study indicated that the ZmLEA5C protein could be phosphorylated by the protein kinase CKII. ZmLEA5C could protect the activity of LDH under water deficit and low temperature stresses. Overexpression of ZmLEA5C conferred to transgenic tobacco (Nicotiana benthamiana) and yeast (GS115) tolerance to osmotic and low temperature stresses.

A maize mitogen-activated protein kinase kinase, ZmMKK1, positively regulated the salt and drought tolerance in transgenic Arabidopsis.

Mitogen-activated protein kinase (MAPK) cascades are highly conserved signal transduction modules in animals, plants and yeast. MAPK cascades are complicated networks and play vital roles in signal transduction pathways involved in biotic and abiotic stresses. In this study, a maize MAPKK gene, ZmMKK1, was characterized. Quantitative real time PCR (qRT-PCR) analysis demonstrated that ZmMKK1 transcripts were induced by diverse stresses and ABA signal molecule in maize root. Further study showed that the ZmMKK1-overexpressing Arabidopsis enhanced the tolerance to salt and drought stresses. However, seed germination, post-germination growth and stomatal aperture analysis demonstrated that ZmMKK1 overexpression was sensitive to ABA in transgenic Arabidopsis. Molecular genetic analysis revealed that the overexpression of ZmMKK1 in Arabidopsis enhanced the expression of ROS scavenging enzyme- and ABA-related genes, such as POD, CAT, RAB18 and RD29A under salt and drought conditions. In addition, heterologous overexpression of ZmMKK1 in yeast (Saccharomyces cerevisiae) improved the tolerance to salt and drought stresses. These results suggested that ZmMKK1 might act as an ABA- and ROS-dependent protein kinase in positive modulation of salt and drought tolerance. Most importantly, ZmMKK1 interacted with ZmMEKK1 as evidenced by yeast two-hybrid assay, redeeming a deficiency of MAPK interaction partners in maize.

Overexpression of tomato chloroplast-targeted DnaJ protein enhances tolerance to drought stress and resistance to Pseudomonas solanacearum in transgenic tobacco.

DnaJ proteins as co-chaperones have critical functions in biotic and abiotic stress responses, but their biological functions remain largely uninvestigated. This study investigates the function of a tomato (Lycopersicon esculentum) chloroplast-targeted DnaJ protein (LeCDJ2) using transgenic tobacco. Quantitative real-time polymerase chain reaction analysis showed that LeCDJ2 expression was triggered by salicylic acid (SA), drought and pathogen attack. Ectopic expression of LeCDJ2 in transgenic tobacco reduced the accumulation of superoxide anion radical (O2(-)) and hydrogen peroxide (H2O2) under drought stress. Compared with Vec plants, the maximum photochemical efficiency of photosystem II (PSII) (Fv/Fm), net photosynthetic rate (Pn), and content of D1 protein were relatively higher in transgenic plants. The transgenic plants showes better growth, higher chlorophyll content, lower malondialdehyde (MDA) accumulation and relative electrolyte leakage (REL) under drought stress. In addition, overexpression of LeCDJ2 improved the resistance to the pathogen Pseudomonas solanacearum in transgenic tobacco. These results indicate that overexpression of a tomato chloroplast-targeted DnaJ gene enhances tolerance to drought stress and resistance to P. solanacearum in transgenic tobacco.

Apolipoprotein E gene variants of Alzheimer's disease and vascular dementia patients in a community population of Nanking.

To explore apolipoprotein E gene variants distribution among the patients of Alzheimer's disease and vascular dementia for the elderly community population in Nanking, the polymerase chain reaction and restriction fragment length polymorphism techniques were employed to analyze the gene frequency of apolipoprotein E (ApoE) for 113 cases with Alzheimer's disease (AD), 85 cases with vascular dementia (VaD), 147 cases with questionable dementia (QD), and 396 dementia-free controls. It was found that ApoE ε4 gene container (37.17%) and allele frequency (21.24 ± 2.72) of ApoE ε4 in AD group were significantly higher than those in both control and VaD group (p < 0.05). With the increment of ε4 gene dose, the incidence of the AD was significantly increased. Compared with the control group, ApoE ε4 had risk ratio (RR) of 1.82 to develop AD (p = 4e-4), and attributable risk percentage (ARP) of 45%. These results suggest that ApoE ε4 gene may be responsible for up to 45% of the genetic component of Alzheimer's disease, and may act as a discriminator between AD and VaD as well.

Ectopic expression of ZmSIMK1 leads to improved drought tolerance and activation of systematic acquired resistance in transgenic tobacco.

The mitogen-activated protein kinase (MAPK) cascades play pivotal roles in diverse signaling pathways related to plant biotic and abiotic stress responses. In this study, a group B MAPK gene in Zea mays, ZmSIMK1, was functionally analyzed. Quantitative real-time PCR (qRT-PCR) analysis indicated that ZmSIMK1 transcript could be induced by drought, salt, Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and certain exogenous signaling molecules. Analysis of the ZmSIMK1 promoter revealed a group of putative cis-acting elements related to drought and defense responses. ß-Glucuronidase (GUS) staining produced similar results as qRT-PCR. ZmSIMK1 was mainly localized in the nucleus, and further study indicated that the C-terminal domain (CD) was essential for targeting to the nucleus. Transgenic tobacco accumulated less reactive oxygen species (ROS), had higher levels of antioxidant enzyme activity and osmoregulatory substances and exhibited an increased germination rate compared with wild-type (WT) tobacco under drought stress. ROS-related and drought stress-responsive genes in transgenic tobacco were significantly upregulated compared with the same genes in WT lines under drought stress. Moreover, overexpression of ZmSIMK1 promoted the hypersensitive response (HR) and pathogen-related gene (PR) transcription in addition to triggering systemic acquired resistance (SAR) in tobacco.

ZmMKK1, a novel group A mitogen-activated protein kinase kinase gene in maize, conferred chilling stress tolerance and was involved in pathogen defense in transgenic tobacco.

As an important intracellular signaling module, the mitogen-activated protein kinase (MAPK) cascades have been previously implicated in signal transduction during plants responsing to various environmental stresses as well as pathogen attack. The mitogen-activated protein kinase kinase acts as the convergent point of MAPK cascades during a variety of stress signaling. In this study, a novel MAPKK gene, ZmMKK1, in maize (Zea mays L.) belonging to group A MAPKK was isolated and functionally characterized. ZmMKK1 was mainly localized in the cytoplasm and its constitutive kinase-active form ZmMKK1DD was localized in both cytoplasm and nucleus. QRT-PCR analysis uncovered that ZmMKK1 expression was triggered by abiotic and biotic stresses and exogenous signaling molecules. Moreover, hydrogen peroxide (H2O2) and Ca(2+) mediated 12°C-induced up-regulated expressing of ZmMKK1 at mRNA level. Ectopic expression of ZmMKK1 in tobacco (Nicotiana tabacum) conferred tolerance to chilling stress by higher antioxidant enzyme activities, more accumulation of osmoregulatory substances and more significantly up-expression of ROS-related and stress-responsive genes compared with empty vector control plants. Furthermore, ZmMKK1 played differential functions in biotrophic versus necrotrophic pathogen-induced responses. These results suggested ZmMKK1 played a crucial role in chilling stress and pathogen defense in plants.

Identification of mitogen-activated protein kinase kinase gene family and MKK-MAPK interaction network in maize.

Plant mitogen-activated protein kinases (MAPK) are involved in important processes, including stress signaling and development. MAPK kinases (MAPKK, MKK) have been investigated in several plant species including Arabidopsis thaliana, Oryza sativa, Populus trichocarpa, and Brachypodium distachyon. In the present study, nine putative maize MKK genes have been identified. Analysis of the conserved protein motifs, exon-intron junctions and intron phase has revealed high levels of conservation within the phylogenetic groups. Next, we defined four new ZmMKK-ZmMPK interactions using yeast two-hybrid. Finally, we examined the biological functions of the ZmMKK4 gene. Overexpression of ZmMKK4 in Arabidopsis conferred tolerance to oxidative stress by increased germination rate and early seedling growth compared with WT plants. Taken together, we provide a comprehensive bioinformatics analysis of the MKK gene family in maize genome and our data provide an important foundation for further functional study of MAPK and MKK families in maize.

Genome-wide identification and expression analysis of calcium-dependent protein kinase in maize.

BACKGROUND: Calcium-dependent protein kinases (CDPKs) have been shown to play important roles in various physiological processes, including plant growth and development, abiotic and biotic stress responses and plant hormone signaling in plants. RESULTS: In this study, we performed a bioinformatics analysis of the entire maize genome and identified 40 CDPK genes. Phylogenetic analysis indicated that 40 ZmCPKs can be divided into four groups. Most maize CDPK genes exhibited different expression levels in different tissues and developmental stages. Twelve CDPK genes were selected to respond to various stimuli, including salt, drought and cold, as well as ABA and H2O2. Expression analyses suggested that maize CDPK genes are important components of maize development and multiple transduction pathways. CONCLUSION: Here, we present a genome-wide analysis of the CDPK gene family in maize for the first time, and this genomic analysis of maize CDPK genes provides the first step towards a functional study of this gene family in maize.

Response of tobacco to the Pseudomonas syringae pv. Tomato DC3000 is mainly dependent on salicylic acid signaling pathway.

Pseudomonas syringae pv. Tomato DC3000 (Pst DC3000) was the first pathogen to be demonstrated to infect Arabidopsis and to cause disease symptoms in the laboratory setting. However, the defense response to Pst DC3000 was unclear in tobacco. In this report, the expression profiles of twelve defense response-related genes were analyzed after treatment with salicylic acid (SA), jasmonic acid (JA), and pathogen Pst DC3000 by qRT-PCR. According to our results, it could be presented that the genes primarily induced by SA were also induced to higher levels after Pst DC3000 infection. SA accumulation could be induced to a higher level than that of JA after Pst DC3000 infection. In addition, SA could result in hypersensitive response (HR), which did not completely depend on accumulation of reactive oxygen species. These results indicated that tobacco mainly depended on SA signaling pathway rather than on JA signaling pathway in response to Pst DC3000. Further study demonstrated that JA could significantly inhibit the accumulation of SA and the generation of the HR induced by Pst DC3000.

Recent insights into brassinosteroid signaling in plants: its dual control of plant immunity and stomatal development.

Brassinosteroid (BR) signaling, plant innate immunity, and stomatal developments are three pathways that are initiated by receptor-like kinases. This commentary focuses on the latest findings in the role of BR signaling in plant immunity and stomatal development that provide some insight into the molecular mechanism of the BR signal pathway interacting with other receptor signaling pathways.