[Online survey on dental anxiety results]. / Online enquête over behandelangst: de resultaten.

In the months leading up to this special on 'dental anxiety', an online survey was conducted on various aspects of the treatment of anxious patients. This survey was completed by 128 people, of whom approximately one third were men and two thirds were women. The results show that more than half of the respondents feel they haven't learned enough about treating anxious patients during the training. Yet more than two thirds of the respondents also indicated they did not refer anxious patients to a Centre for Special Dentistry. The reasons for this are not clear.

[Sexual trauma; treatability in the dental practice]. / Seksueel trauma; behandelbaarheid in de tandartspraktijk.

A patient with extreme fear of dental treatment and a history of sexual abuse as well presented at a Centre for Special Care Dentistry. A dentist specializing in dental anxiety and a clinical psychologist worked closely together during intake and treatment phases. The comorbid PTSS appeared to hamper the exposure therapy. In consultation with the patient, she was referred to a specialized inpatient unit for intensive trauma treatment. This trauma treatment took place parallel to the exposure treatment at the dentist's. When the trauma had been treated successfully, further treatment at the dentist's for anxiety counselling also proceeded much more smoothly. At the end of the anxiety treatment, the patient was referred back to the regular dental practice.

[Diagnosis and treatment of dental anxiety]. / Diagnostiek en behandeling van angst voor de tandheelkundige behandeling.

Fear of dental treatment is a common phenomenon. Every oral health care provider will have to treat a patient with this fear one day. Adequate diagnostics are essential for a correct assessment of the level of fear and how an anxious patient can best be helped. In cases of mild fear, lowering the state anxiety by teaching the patient coping skills, will suffice. In cases of extreme fear, reducing disposition anxiety (the core of the anxiety disorder) comes first, since this will not only reduce fear during the treatment, but will also halt avoidance behavior, which in the end will have a positive effect on the oral health care of the patient.

No priming, just fighting-endophytic yeast attenuates the defense response and the stress induced by Dutch elm disease in Ulmus minor Mill.

One century after the first report of Dutch elm disease (DED), there is still no practical solution for this problem threatening European and American elms (Ulmus spp.). The long breeding cycles needed to select resistant genotypes and the lack of efficient treatments keep disease incidence at high levels. In this work, the expression of defense-related genes to the causal agent of DED, Ophiostoma novo-ulmi Brasier, was analyzed in in vitro clonal plantlets from two DED-resistant and two DED-susceptible Ulmus minor Mill. trees. In addition, the effect of the inoculation of an endophytic pink-pigmented yeast (Cystobasidium sp.) on the plant's defense system was tested both individually and in combination with O. novo-ulmi. The multifactorial nature of the resistance to DED was confirmed, as no common molecular response was found in the two resistant genotypes. However, the in vitro experimental system allowed discrimination of the susceptible from the resistant genotypes, showing higher levels of oxidative damage and phenolic compounds in the susceptible genotypes after pathogen inoculation. Inoculation of the endophyte before O. novo-ulmi attenuated the plant molecular response induced by the pathogen and moderated oxidative stress levels. Niche competition, endophyte-pathogen antagonism and molecular crosstalk between the host and the endophyte are discussed as possible mechanisms of stress reduction. In sum, our results confirm the complex and heterogeneous nature of DED resistance mechanisms and highlight the possibility of using certain endophytic yeasts as biological tools to improve tree resilience against biotic stress.

[Administration of intravenous sedation with midazolam by dentists is unsafe]. / Toediening van intraveneuze sedatie met midazolam door tandarts is onveilig.

In the December issue of the Nederlands Tijdschrift voor Tandheelkunde (Dutch Journal of Dentistry) in 2014, an article was devoted to the use of light sedation with midazolam by dentists. A number of dentists who are active in the area of Special Dentistry (anxiety management, care of the disabled) and a anesthesiologist offer a response to the article and argue that the administration of intravenous sedation with midazolam by dentists is unsafe.

Cross activity of orthologous WRKY transcription factors in wheat and Arabidopsis.

WRKY proteins are transcription factors involved in many plant processes including plant responses to pathogens. Here, the cross activity of TaWRKY78 from the monocot wheat and AtWRKY20 from the dicot Arabidopsis on the cognate promoters of the orthologous PR4-type genes wPR4e and AtHEL of wheat and Arabidopsis, respectively, was investigated. In vitro analysis showed the ability of TaWRKY78 to bind a -17/+80 region of the wPR4e promoter, containing one cis-acting W-box. Moreover, transient expression analysis performed on both TaWRKY78 and AtWRKY20 showed their ability to recognize the cognate cis-acting elements present in the wPR4e and AtHEL promoters, respectively. Finally, this paper provides evidence that both transcription factors are able to cross-regulate the orthologous PR4 genes with an efficiency slightly lower than that exerted on the cognate promoters. The observation that orthologous genes are subjected to similar transcriptional control by orthologous transcription factors demonstrates that the terminal stages of signal transduction pathways leading to defence are conserved and suggests a fundamental role of PR4 genes in plant defence. Moreover, these results corroborate the hypothesis that gene orthology imply similar gene function and that diversification between monocot and dicot has most likely occurred after the specialization of WRKY function.

MYB72, a node of convergence in induced systemic resistance triggered by a fungal and a bacterial beneficial microbe.

Colonisation of plant roots by selected beneficial Trichoderma fungi or Pseudomonas bacteria can result in the activation of a systemic defence response that is effective against a broad spectrum of pathogens. In Arabidopsis thaliana, induced systemic resistance (ISR) triggered by the rhizobacterial strain Pseudomonas fluorescens WCS417r is regulated by a jasmonic acid- and ethylene-dependent defence signalling pathway. Jasmonic acid and ethylene also play a role in Trichoderma-induced resistance. To further investigate the similarities between rhizobacteria- and Trichoderma-induced resistance, we studied the response of Arabidopsis to root colonisation by Trichoderma asperellum T34. In many aspects T34-ISR was similar to WCS417r-ISR. First, colonisation of the roots by T34 rendered the leaves more resistant to the bacterial pathogen Pseudomonas syringae pv. tomato, the biotrophic oomycete Hyaloperonospora parasitica and the necrotrophic fungus Plectosphaerella cucumerina. Second, treatment of the roots with T34 primed the leaf tissue for enhanced jasmonic acid-responsive gene expression and increased formation of callose-containing papillae upon pathogen attack. Third, T34-ISR was fully expressed in the salicylic acid impaired mutant sid2, but blocked in the defence regulatory mutant npr1. Finally, we show that the root-specific transcription factor MYB72, which is essential in early signalling steps of WCS417r-ISR, is also required for T34-ISR. Together, these results indicate that the defence pathways triggered by beneficial Trichoderma and Pseudomonas spp. strains are highly similar and that MYB72 functions as an early node of convergence in the signalling pathways that are induced by these different beneficial microorganisms.

[Post-academic dental specialties 13. What are anxious dental patients most afraid of?]. / Beroepsdifferentiatie in de tandheelkunde 13. Waar zijn angstige patienten het meest bang voor?

What are the dental stimuli and situations that are experienced as more or less fear provoking by anxious dental patients?To investigate this question, 81 highly anxious patients, who were referred to a centre of special dental care were presented with a list of 76 potentially fear provoking objects and situations. The results showed that invasive dental procedures are considered as most terrifying by anxious patients, and that stimuli related to the dental office (dental chair), the dental team (dentist) and their equipment (protecting clothes) are considered as least fear provoking. Root canal treatments were rated as most fear provoking. The results emphasize the importance of assessing the whole range of potentially terrifying stimuli for each anxious patient. Only in this way an approach focused on the extinction of patients' dental fear can be successful.

Significance of inducible defense-related proteins in infected plants.

Inducible defense-related proteins have been described in many plant species upon infection with oomycetes, fungi, bacteria, or viruses, or insect attack. Several types of proteins are common and have been classified into 17 families of pathogenesis-related proteins (PRs). Others have so far been found to occur more specifically in some plant species. Most PRs and related proteins are induced through the action of the signaling compounds salicylic acid, jasmonic acid, or ethylene, and possess antimicrobial activities in vitro through hydrolytic activities on cell walls, contact toxicity, and perhaps an involvement in defense signaling. However, when expressed in transgenic plants, they reduce only a limited number of diseases, depending on the nature of the protein, plant species, and pathogen involved. As exemplified by the PR-1 proteins in Arabidopsis and rice, many homologous proteins belonging to the same family are regulated developmentally and may serve different functions in specific organs or tissues. Several defense-related proteins are induced during senescence, wounding or cold stress, and some possess antifreeze activity. Many defense-related proteins are present constitutively in floral tissues and a substantial number of PR-like proteins in pollen, fruits, and vegetables can provoke allergy in humans. The evolutionary conservation of similar defense-related proteins in monocots and dicots, but also their divergent occurrence in other conditions, suggest that these proteins serve essential functions in plant life, whether in defense or not.

The arabidopsis ISR1 locus controlling rhizobacteria-mediated induced systemic resistance is involved in ethylene signaling.

In Arabidopsis, the rhizobacterial strain Pseudomonas fluorescens WCS417r triggers an induced systemic resistance (ISR) response that is effective against different types of pathogens. The ISR signaling pathway functions independent of salicylic acid, but requires responsiveness to jasmonate (JA) and ethylene. Using the genetic variability of ISR inducibility between Arabidopsis accessions, we recently identified a locus (ISR1) on chromosome III that is involved in ISR signaling. Accessions RLD and Wassilewskija (Ws) are recessive at the ISR1 locus and are, therefore, unable to develop ISR. Here we investigated whether the ISR1 locus is involved in JA or ethylene signaling. Compared with the ISR-inducible accession Columbia (Col), accessions RLD and Ws were not affected in JA-induced inhibition of root growth and expression of the JA-responsive gene Atvsp, suggesting that the ISR1 locus is not involved in JA signaling. However, RLD and Ws showed an affected expression of the triple response and a reduced expression of the ethylene responsive genes Hel and Pdf1.2 after exogenous application of the ethylene precursor 1-aminocyclopropane-1-carboxylate. Moreover, in contrast to Col, RLD and Ws did not develop resistance against P. syringae pv. tomato DC3000 after treatment of the leaves with 1-aminocyclopropane-1-carboxylate. Analysis of the F(2) and F(3) progeny of a cross between Col (ISR1/ISR1) and RLD (isr1/isr1) revealed that reduced sensitivity to ethylene cosegregates with the recessive alleles of the ISR1 locus. These results suggest that the ISR1 locus encodes a component of the ethylene response, which is required for the expression of rhizobacteria-mediated ISR.

Enhancement of induced disease resistance by simultaneous activation of salicylate- and jasmonate-dependent defense pathways in Arabidopsis thaliana.

The plant-signaling molecules salicylic acid (SA) and jasmonic acid (JA) play an important role in induced disease resistance pathways. Cross-talk between SA- and JA-dependent pathways can result in inhibition of JA-mediated defense responses. We investigated possible antagonistic interactions between the SA-dependent systemic acquired resistance (SAR) pathway, which is induced upon pathogen infection, and the JA-dependent induced systemic resistance (ISR) pathway, which is triggered by nonpathogenic Pseudomonas rhizobacteria. In Arabidopsis thaliana, SAR and ISR are effective against a broad spectrum of pathogens, including the foliar pathogen Pseudomonas syringae pv. tomato (Pst). Simultaneous activation of SAR and ISR resulted in an additive effect on the level of induced protection against Pst. In Arabidopsis genotypes that are blocked in either SAR or ISR, this additive effect was not evident. Moreover, induction of ISR did not affect the expression of the SAR marker gene PR-1 in plants expressing SAR. Together, these observations demonstrate that the SAR and the ISR pathway are compatible and that there is no significant cross-talk between these pathways. SAR and ISR both require the key regulatory protein NPR1. Plants expressing both types of induced resistance did not show elevated Npr1 transcript levels, indicating that the constitutive level of NPR1 is sufficient to facilitate simultaneous expression of SAR and ISR. These results suggest that the enhanced level of protection is established through parallel activation of complementary, NPR1-dependent defense responses that are both active against Pst. Therefore, combining SAR and ISR provides an attractive tool for the improvement of disease control.

Rhizobacteria-mediated induced systemic resistance (ISR) in Arabidopsis is not associated with a direct effect on expression of known defense-related genes but stimulates the expression of the jasmonate-inducible gene Atvsp upon challenge.

Selected strains of nonpathogenic rhizobacteria from the genus Pseudomonas are capable of eliciting broad-spectrum induced systemic resistance (ISR) in plants that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). In Arabidopsis, the ISR pathway functions independently of salicylic acid (SA) but requires responsiveness to jasmonate and ethylene. Here, we demonstrate that known defense-related genes, i.e. the SA-responsive genes PR-1, PR-2, and PR-5, the ethylene-inducible gene Hel, the ethylene- and jasmonate-responsive genes ChiB and Pdf1.2, and the jasmonate-inducible genes Atvsp, Lox1, Lox2, Pall, and Pin2, are neither induced locally in the roots nor systemically in the leaves upon induction of ISR by Pseudomonas fluorescens WCS417r. In contrast, plants infected with the virulent leaf pathogen Pseudomonas syringae pv. tomato (Pst) or expressing SAR induced by preinfecting lower leaves with the avirulent pathogen Pst(avrRpt2) exhibit elevated expression levels of most of the defense-related genes studied. Upon challenge inoculation with Pst, PR gene transcripts accumulated to a higher level in SAR-expressing plants than in control-treated and ISR-expressing plants, indicating that SAR involves potentiation of SA-responsive PR gene expression. In contrast, pathogen challenge of ISR-expressing plants led to an enhanced level of Atvsp transcript accumulation. The otherjasmonate-responsive defense-related genes studied were not potentiated during ISR, indicating that ISR is associated with the potentiation of specific jasmonate-responsive genes.

Identification of a locus in arabidopsis controlling both the expression of rhizobacteria-mediated induced systemic resistance (ISR) and basal resistance against Pseudomonas syringae pv. tomato.

Selected nonpathogenic rhizobacteria with biological disease control activity are able to elicit an induced systemic resistance (ISR) response that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). Ten ecotypes of Arabidopsis thaliana were screened for their potential to express rhizobacteria-mediated ISR and pathogen-induced SAR against the leaf pathogen Pseudomonas syringae pv. tomato DC3000 (Pst). All ecotypes expressed SAR. However, of the 10 ecotypes tested, ecotypes RLD and Wassilewskija (Ws) did not develop ISR after treatment of the roots with nonpathogenic Pseudomonas fluorescens WCS417r bacteria. This nonresponsive phenotype was associated with relatively high susceptibility to Pst infection. The F1 progeny of crosses between the non-responsive ecotypes RLD and Ws on the one hand, and the responsive ecotypes Columbia (Col) and Landsberg erecta (Ler) on the other hand, were fully capable of expressing ISR and exhibited a relatively high level of basal resistance, similar to that of their WCS417r-responsive parent. This indicates that the potential to express ISR and the relatively high level of basal resistance against Pst are both inherited as dominant traits. Analysis of the F2 and F3 progeny of a Col x RLD cross revealed that inducibility of ISR and relatively high basal resistance against Pst cosegregate in a 3:1 fashion, suggesting that both resistance mechanisms are monogenically determined and genetically linked. Neither the responsiveness to WCS417r nor the relatively high level of basal resistance against Pst were complemented in the F1 progeny of crosses between RLD and Ws, indicating that RLD and Ws are both affected in the same locus, necessary for the expression of ISR and basal resistance against Pst. The corresponding locus, designated ISR1, was mapped between markers B4 and GL1 on chromosome 3. The observed association between ISR and basal resistance against Pst suggests that rhizobacteria-mediated ISR against Pst in Arabidopsis requires the presence of a single dominant gene that functions in the basal resistance response against Pst infection.

Systemic resistance in Arabidopsis induced by rhizobacteria requires ethylene-dependent signaling at the site of application.

Root colonization of Arabidopsis thaliana by the nonpathogenic, rhizosphere-colonizing, biocontrol bacterium Pseudomonas fluorescens WCS417r has been shown to elicit induced systemic resistance (ISR) against Pseudomonas syringae pv. tomato (Pst). The ISR response differs from the pathogen-inducible systemic acquired resistance (SAR) response in that ISR is independent of salicylic acid and not associated with pathogenesis-related proteins. Several ethylene-response mutants were tested and showed essentially normal symptoms of Pst infection. ISR was abolished in the ethylene-insensitive mutant etr1-1, whereas SAR was unaffected. Similar results were obtained with the ethylene-insensitive mutants ein2 through ein7, indicating that the expression of ISR requires the complete signal-transduction pathway of ethylene known so far. The induction of ISR by WCS417r was not accompanied by increased ethylene production in roots or leaves, nor by increases in the expression of the genes encoding the ethylene biosynthetic enzymes 1-aminocyclopropane-1-carboxylic (ACC) synthase and ACC oxidase. The eir1 mutant, displaying ethylene insensitivity in the roots only, did not express ISR upon application of WCS417r to the roots, but did exhibit ISR when the inducing bacteria were infiltrated into the leaves. These results demonstrate that, for the induction of ISR, ethylene responsiveness is required at the site of application of inducing rhizobacteria.

A novel signaling pathway controlling induced systemic resistance in Arabidopsis.

Plants have the ability to acquire an enhanced level of resistance to pathogen attack after being exposed to specific biotic stimuli. In Arabidopsis, nonpathogenic, root-colonizing Pseudomonas fluorescens bacteria trigger an induced systemic resistance (ISR) response against infection by the bacterial leaf pathogen P. syringae pv tomato. In contrast to classic, pathogen-induced systemic acquired resistance (SAR), this rhizobacteria-mediated ISR response is independent of salicylic acid accumulation and pathogenesis-related gene activation. Using the jasmonate response mutant jar1, the ethylene response mutant etr1, and the SAR regulatory mutant npr1, we demonstrate that signal transduction leading to P. fluorescens WCS417r-mediated ISR requires responsiveness to jasmonate and ethylene and is dependent on NPR1. Similar to P. fluorescens WCS417r, methyl jasmonate and the ethylene precursor 1-aminocyclopropane-1-carboxylate were effective in inducing resistance against P. s. tomato in salicylic acid-nonaccumulating NahG plants. Moreover, methyl jasmonate-induced protection was blocked in jar1, etr1, and npr1 plants, whereas 1-aminocyclopropane-1-carboxylate-induced protection was affected in etr1 and npr1 plants but not in jar1 plants. Hence, we postulate that rhizobacteria-mediated ISR follows a novel signaling pathway in which components from the jasmonate and ethylene response are engaged successively to trigger a defense reaction that, like SAR, is regulated by NPR1. We provide evidence that the processes downstream of NPR1 in the ISR pathway are divergent from those in the SAR pathway, indicating that NPR1 differentially regulates defense responses, depending on the signals that are elicited during induction of resistance.

Systemic resistance induced by rhizosphere bacteria.

Nonpathogenic rhizobacteria can induce a systemic resistance in plants that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). Rhizobacteria-mediated induced systemic resistance (ISR) has been demonstrated against fungi, bacteria, and viruses in Arabidopsis, bean, carnation, cucumber, radish, tobacco, and tomato under conditions in which the inducing bacteria and the challenging pathogen remained spatially separated. Bacterial strains differ in their ability to induce resistance in different plant species, and plants show variation in the expression of ISR upon induction by specific bacterial strains. Bacterial determinants of ISR include lipopolysaccharides, siderophores, and salicylic acid (SA). Whereas some of the rhizobacteria induce resistance through the SA-dependent SAR pathway, others do not and require jasmonic acid and ethylene perception by the plant for ISR to develop. No consistent host plant alterations are associated with the induced state, but upon challenge inoculation, resistance responses are accelerated and enhanced. ISR is effective under field conditions and offers a natural mechanism for biological control of plant disease.

Differential induction of systemic resistance in Arabidopsis by biocontrol bacteria.

Selected nonpathogenic, root-colonizing bacteria are able to elicit induced systemic resistance (ISR) in plants. To elucidate the molecular mechanisms underlying this type of systemic resistance, an Arabidopsis-based model system was developed in which Pseudomonas syringae pv. tomato and Fusarium oxysporum f. sp. raphani were used as challenging pathogens. In Arabidopsis thaliana ecotypes Columbia and Landsberg erecta, colonization of the rhizosphere by P. fluorescens strain WCS417r induced systemic resistance against both pathogens. In contrast, ecotype RLD did not respond to WCS417r treatment, whereas all three ecotypes expressed systemic acquired resistance upon treatment with salicylic acid (SA). P. fluorescens strain WCS374r, previously shown to induce ISR in radish, did not elicit ISR in Arabidopsis. The opposite was found for P. putida strain WCS358r, which induced ISR in Arabidopsis but not in radish. These results demonstrate that rhizosphere pseudomonads are differentially active in eliciting ISR in related plant species. The outer membrane lipopolysaccharide (LPS) of WCS417r is the main ISR-inducing determinant in radish and carnation, and LPS-containing cell walls also elicit ISR in Arabidopsis. However, mutant WCS417rOA-, lacking the O-antigenic side chain of the LPS, induced levels of protection similar to those induced by wild-type WCS417r. This indicates that ISR-inducing bacteria produce more than a single factor that trigger ISR in Arabidopsis. Furthermore, WCS417r and WCS358r induced protection in both wild-type Arabidopsis and SA-nonaccumulating NahG plants without activating pathogenesis-related gene expression. This suggests that elicitation of an SA-independent signaling pathway is a characteristic feature of ISR-inducing biocontrol bacteria.

Systemic resistance in Arabidopsis induced by biocontrol bacteria is independent of salicylic acid accumulation and pathogenesis-related gene expression.

Systemic acquired resistance is a pathogen-inducible defense mechanism in plants. The resistant state is dependent on endogenous accumulation of salicylic acid (SA) and is characterized by the activation of genes encoding pathogenesis-related (PR) proteins. Recently, selected nonpathogenic, root-colonizing biocontrol bacteria have been shown to trigger a systemic resistance response as well. To study the molecular basis underlying this type of systemic resistance, we developed an Arabidopsis-based model system using Fusarium oxysporum f sp raphani and Pseudomonas syringae pv tomato as challenging pathogens. Colonization of the rhizosphere by the biological control strain WCS417r of P. fluorescens resulted in a plant-mediated resistance response that significantly reduced symptoms elicited by both challenging pathogens. Moreover, growth of P. syringae in infected leaves was strongly inhibited in P. fluorescens WCS417r-treated plants. Transgenic Arabidopsis NahG plants, unable to accumulate SA, and wild-type plants were equally responsive to P. fluorescens WCS417r-mediated induction of resistance. Furthermore, P. fluorescens WCS417r-mediated systemic resistance did not coincide with the accumulation of PR mRNAs before challenge inoculation. These results indicate that P. fluorescens WCS417r induces a pathway different from the one that controls classic systemic acquired resistance and that this pathway leads to a form of systemic resistance independent of SA accumulation and PR gene expression.

NiaA, the structural nitrate reductase gene of Phytophthora infestans: isolation, characterization and expression analysis in Aspergillus nidulans.

The nitrate reductase (NR) gene niaA of the oomycete Phytophthora infestans was selected from a gene library by heterologous hybridization. NiaA occurs as a single-copy gene ant its expression is regulated by the nitrogen source. The nucleotide sequence of niaA was determined and comparison of the deduced amino-acid sequence of 902 residues with NRs of higher fungi and plants revealed a significant homology, particularly within the three cofactor-binding domains for molybdenum, heme and FAD. The P. infestans niaA gene was used as a model gene to test whether oomycete genes are functional in the ascomycete Aspergillus nidulans, a fungus which is highly accessible for molecular genetic studies. The complete niaA gene was stably integrated into the genome of a nia- deletion mutant of A. nidulans. However, transformants containing one or more copies of the niaA gene were not able to complement the nia- mutant. This suggests that there is no functional expression of the introduced niaA gene in A. nidulans. In addition, the activity of two other oomycete gene promoters was analyzed in a transient expression assay. Plasmids containing chimaeric genes with the promoter of the P. infestans ubiquitin gene ubi3R, or the Bremia lactucae ham34 gene, fused to the coding sequence of the Escherichia coli beta-glucuronidase (GUS) reporter gene, were transferred to A. nidulans protoplasts. No significant GUS activity was detectable indicating that the ubi3R and ham34 promoters are not active in A. nidulans. Apparently, the regulatory sequences which are sufficient for gene activation in oomycetes are not functional in the ascomycete A. nidulans.