Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 88
Filter
1.
BJUI Compass ; 5(4): 439-446, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38633824

ABSTRACT

Objective: The objective of this study is to assess the impact of overnight environmental conditions on erectile penile temperature within a controlled setting, with the aim of investigating the feasibility of using temperature measurements for nocturnal erection detection in erectile dysfunction diagnostics. Subjects/patients and methods: We conducted a proof-of-concept study involving 10 healthy male participants aged 20 to 25. The study was carried out at the Department of Urology, St. Antonius Ziekenhuis, the Netherlands. Penile temperature thermistor measurements were taken during visually aroused erections of participants in naked state and in simulated overnight condition (underwear and blankets). Main outcome variables were peak and baseline temperature during erectile periods. To minimize the impact of differences in erectile strength and duration between consecutive measurements, we applied randomization to the order of the environmental conditions. Results: We observed a significant increase in penile temperature during erection in both the naked (p < 0.01) and simulated overnight condition (p < 0.01). The mean temperature increase was 1.70 and 0.67°C, respectively. While penile temperature returned to baseline immediately after naked erections, the 'Staying Hot effect' was noted in the simulated overnight condition measurements, where the temperature remained elevated at peak temperature for the entire 30-min period following the erection. Conclusions: The findings from this study indicate that the penile temperature not only significantly increases during naked sexual arousal but is also detectable under simulated overnight conditions. This underscores the potential of using temperature measurements for nocturnal erection detection, representing a crucial initial step in developing a modernized, non-invasive sensor system for ambulatory erectile dysfunction diagnostics. Further research, including an overnight study, is needed to gain insights into the feasibility of utilizing penile temperature measurements for nocturnal erection detection and to assess the impact of the 'Staying Hot effect' on subsequent erection detection.

6.
J Laryngol Otol ; 125(8): 837-40, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21729447

ABSTRACT

AIM: To investigate the incidence of metastasis to the submandibular gland in patients with head and neck squamous cell carcinoma. METHODS: We retrospectively evaluated histological reports of neck dissections for upper respiratory tract carcinoma (performed 2002-2009), recording: primary tumour site, tumour-node-metastasis stage, level Ib involvement, previous radiotherapy, perineural invasion, lymphovascular invasion, extracapsular spread, and the presence of malignant disease in the submandibular gland. RESULTS: We evaluated 107 cases. The most common primary site was the oral cavity (49 per cent) followed by the supraglottis (21 per cent), glottis (14 per cent), oropharynx (9 per cent) and hypopharynx (6 per cent). Forty-eight per cent of patients had advanced local disease, with 21 per cent at tumour stage 3 and 27 per cent at tumour stage 4. Fifty-six per cent had cervical lymph node metastasis, and 8 per cent received pre-operative radiotherapy. Forty-eight per cent had perineural invasion, 46 per cent lymphovascular spread, 27 per cent extracapsular spread and 8 per cent level Ib metastasis. Only one patient had submandibular gland involvement, due to direct spread (a case with prior radiotherapy and macroscopic submandibular gland involvement evident peri-operatively). CONCLUSION: Submandibular gland metastasis from head and neck primary squamous cell carcinoma is extremely rare. Preservation of the ipsilateral submandibular gland during neck dissection is oncologically safe, except in patients with prior surgery or radiotherapy, or a primary tumour in close relation to the gland.


Subject(s)
Carcinoma/surgery , Head and Neck Neoplasms/surgery , Neck Dissection/methods , Neoplasms, Squamous Cell/surgery , Submandibular Gland Neoplasms/secondary , Submandibular Gland/surgery , Carcinoma/epidemiology , Carcinoma/pathology , Carcinoma, Squamous Cell , Head and Neck Neoplasms/epidemiology , Head and Neck Neoplasms/pathology , Humans , Lymphatic Metastasis , Neoplasm Invasiveness , Neoplasm Staging , Neoplasms, Squamous Cell/epidemiology , Neoplasms, Squamous Cell/pathology , Retrospective Studies , Saliva , Squamous Cell Carcinoma of Head and Neck , Submandibular Gland/pathology , Submandibular Gland Neoplasms/epidemiology , Submandibular Gland Neoplasms/surgery , Treatment Outcome , Xerostomia/etiology , Xerostomia/prevention & control
7.
Plant Biol (Stuttg) ; 10 Suppl 1: 85-98, 2008 Sep.
Article in English | MEDLINE | ID: mdl-18721314

ABSTRACT

Reactive oxygen species (ROS) are the inevitable by-products of essential cellular metabolic and physiological activities. Plants have developed sophisticated gene networks of ROS generation and scavenging systems. However, ROS regulation is still poorly understood. Here, we report that mutations in the Arabidopsis CPR5/OLD1 gene may cause early senescence through deregulation of the cellular redox balance. Genetic analysis showed that blocking stress-related hormonal signalling pathways, such as ethylene, salicylic acid, jasmonic acid, abscisic acid and sugar, did not affect premature cell death and leaf senescence. We took a bioinformatics approach and analysed publicly available transcriptome data of presymptomatic cpr5/old1 mutants. The results demonstrate that many genes in the ROS gene network show at least fivefold increases in transcripts in comparison with those of wild-type plants, suggesting that presymptomatic cpr5/old1 mutants are in a state of high-cellular oxidative stress. This was further confirmed by a comparative, relative quantitative proteomics study of Arabidopsis wild-type and cpr5/old1 mutant plants, which demonstrated that several Phi family members of glutathione s-transferases significantly increased in abundance. In summary, our genetic, transcriptomic and relative quantitative proteomics analyses indicate that CPR5 plays a central role in regulating redox balance in Arabidopsis.


Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis/genetics , Cellular Senescence , Membrane Proteins/genetics , Apoptosis/genetics , Arabidopsis/drug effects , Arabidopsis/physiology , Computational Biology , Electrophoresis, Gel, Two-Dimensional , Gene Expression Profiling , Genetic Markers , Glutathione Transferase/metabolism , Mutation , Oxidation-Reduction , Oxidative Stress/genetics , Plant Growth Regulators/pharmacology , Plant Leaves/drug effects , Plant Leaves/genetics , Plant Leaves/physiology , Proteomics , Reactive Oxygen Species/metabolism , Signal Transduction , Transcription Factors/genetics , Transcription Factors/metabolism
8.
Cent Afr J Med ; 52(5-6): 51-5, 2006.
Article in English | MEDLINE | ID: mdl-18254455

ABSTRACT

OBJECTIVE: Annual reports from the few cancer registries in Africa are the only reliable assessment of the burden of cancer using population-based data. Similar reports for oral malignancies have not been undertaken. The purpose of this study was to assess the burden of oral malignancies in Zimbabwe over a 10 year period using population-based data. DESIGN: A descriptive epidemiological study was undertaken to assess the burden of oral malignancies by determining the frequencies, incidence and cumulative rates, the lifetime risk and chances of developing an oral malignancy according to site (topography), gender, age, morphology and race/ethnic origin of the Zimbabwean population. A total of 873 incident cases of oral malignancies from the upper and lower lips, oral vestibule, retromolar area, floor of mouth, tongue, cheek mucosa, gums, hard and soft palate were accessed from the Zimbabwe National Cancer Registry (ZNCR). Cases from the skin, pharynx, larynx and the major salivary glands were excluded from the study. SETTING: This comprised the population of Zimbabwe during a 10 year period 1988 to 1997. The population figures used for this study were from the 1992 Census Zimbabwe National Report. The study population was standardised by the direct method against the world standard population to calculate the age standardized incidence rate (ASIR). The SPSS statistical software program (SPSS Inc.2001, USA) was used for the statistical analysis. RESULTS: Oral malignancies comprised 1.8% of total body malignancies with high histological confirmation of the diagnosis (77.3%). The 25 to 29 and 30 to 34 five-year age groups were the most and equally affected by oral malignancies. The mean age was 43.9 years and median age was 41 years [standard deviation (SD) = 17.7] excluding 53 cases of'unknown age'. Oral Kaposi's sarcoma (OKS) and oral squamous cell carcinoma (OSCC) were the predominant forms of oral malignancy. The palate was the most commonly affected site by oral malignancy followed by, in descending order, the tongue, mouth, floor of mouth and the gum. Blacks were affected more than whites and males more than females (sex ratio = 1.97:1). The palate and the tongue were the most commonly affected sites in blacks and whites respectively. OKS affected mostly young adults while OSCC was the commonest malignancy of the elderly. The tongue had more OSCC (60.4%) than OKS (31%). CONCLUSIONS: Lip cancer was three times more common in whites than in blacks and affected mostly the elderly, though females irrespective of race had a higher lifetime risk for malignancy of the lower lip. The high incidence of OKS among young adults was due to the HIV/AIDS epidemic.


Subject(s)
Mouth Neoplasms/epidemiology , Adult , Epidemiologic Studies , Ethnicity , Female , Humans , Male , Mouth Neoplasms/physiopathology , Registries , Retrospective Studies , Risk Factors , Zimbabwe/epidemiology
9.
Ann Acad Med Singap ; 33(4 Suppl): 53-8, 2004 Jul.
Article in English | MEDLINE | ID: mdl-15389309

ABSTRACT

INTRODUCTION: Six cases are reported, each presented at the 11th Biennial Congress of the International Association of Oral Pathologists as an instructive case for differential diagnosis on the basis of clinical, imaging or histological features. CLINICAL PICTURE: Case diagnoses included a large, possibly intraosseous, myofibroma presenting with an oral mass; Langerhans cell histiocytosis with facial skin lesions; an intraosseous vascular hamartoma of the maxilla with worrying radiological features; an unusual mixed radiolucency of the jaw caused by cemento-ossifying fibroma; an osteosarcoma of the posterior mandible causing a well-defined radiolucency and an intraoral squamous cell carcinoma in a child.


Subject(s)
Bone Neoplasms/diagnostic imaging , Carcinoma, Squamous Cell/diagnosis , Fibroma, Ossifying/diagnostic imaging , Hamartoma/diagnostic imaging , Histiocytosis, Langerhans-Cell/diagnosis , Jaw Neoplasms/diagnostic imaging , Maxillary Diseases/diagnostic imaging , Mouth Neoplasms/diagnosis , Myofibroma/diagnosis , Osteosarcoma/diagnosis , Adolescent , Adult , Child , Dental Cementum/diagnostic imaging , Diagnosis, Differential , Facial Dermatoses/complications , Female , Humans , Infant , Male , Radiography
10.
Cell Mol Life Sci ; 61(10): 1185-97, 2004 May.
Article in English | MEDLINE | ID: mdl-15141304

ABSTRACT

A T-DNA knockout of the Arabidopsis homologue of the tomato disease resistance gene Asc was obtained. The asc gene renders plants sensitive to programmed cell death (PCD) triggered by the fungal AAL toxin. To obtain more insights into the nature of AAL-toxin-induced cell death and to identify genes of potential importance for PCD, we carried out transcription profiling of AAL-toxin-induced cell death in this knockout with an oligonucleotide array representing 21,500 Arabidopsis genes. Genes responsive to reactive oxygen species (ROS) and ethylene were among the earliest to be upregulated, suggesting that an oxidative burst and production of ethylene played a role in the activation of the cell death. This notion was corroborated by induction of several genes encoding ROS-generating proteins, including a respiratory burst oxidase and germin oxalate oxidase. Cytochemical studies confirmed the oxidative burst and, in addition, showed synthesis of callose, a feature of the hypersensitive response. A diverse group of transcription factors was also induced. These events were followed by repression of most of the auxin-regulated genes known to be involved in growth and developmental responses. All photosynthesis-related genes were repressed. Blocking the synthesis of ethylene or NO significantly compromised cell death. In addition, we identified a heterogeneous group of early-induced genes, some of them never before associated with PCD. The group of early-induced genes included a number of proteases that were previously implicated in developmentally regulated types of PCD, suggesting a more principal role for these proteases in the PCD process. These findings provide new insights into the molecular mechanisms of plant PCD.


Subject(s)
Apoptosis , Arabidopsis/drug effects , Arabidopsis/metabolism , Oligonucleotide Array Sequence Analysis , Sphingosine/pharmacology , Blotting, Northern , Cell Death , Ethylenes/pharmacology , Hydrogen Peroxide/pharmacology , Models, Biological , Plants, Genetically Modified , Proteome , Reactive Oxygen Species , Respiratory Burst , Time Factors , Transcription, Genetic
11.
Oral Dis ; 8 Suppl 2: 161-8, 2002.
Article in English | MEDLINE | ID: mdl-12164651

ABSTRACT

Opportunistic DNA viruses, particularly members of the herpesvirus family, are frequently the aetiological agents of HIV-associated oral lesions. Oral lesions common to the early phase of the AIDS epidemic, including Kaposi's sarcoma (KS), oral aphthous ulceration, AIDS-associated oral lymphoma, and oral hairy leukoplakia (OHL), have been tested for the prevalence of Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV). While EBV DNA is detected by PCR in all of these lesions, abundant viral replication can only be detected in OHL. In OHL, a novel state of EBV infection has been discovered with concurrent expression of replicative and transforming proteins, with all of these proteins contributing to the development of the lesion. Activation of signalling pathways and up-regulation of the viral receptor, proliferative and antiapoptotic genes by these proteins induce several of the histological features common to OHL, such as acanthosis and hyperproliferation. In contrast to other permissive herpesvirus infections, expression of EBV transforming proteins within the permissively infected OHL tissue enables epithelial cell survival and may enhance viral replication. Detection of KSHV in these HIV-infected individuals has been localized only to their saliva. Replicative and latent KSHV gene products have been detected in association with the development of oral KS lesions. EBV, but not human cytomegalovirus (HCMV), has been detected by PCR in minor salivary gland biopsies of HIV-associated salivary gland disease. Human papillomaviruses (HPV) are associated with oral warts in HIV-positive individuals; a diagnosis that appears to be increasing in frequency in the era of highly active antiretroviral therapy. To date, there appears to be little increase in the incidence of HPV-associated oral cancer. The mechanisms of interaction between HIV and HPV are not fully understood. Expression of viral gene products is clearly important and necessary for the development of multiple AIDS-associated oral lesions.


Subject(s)
AIDS-Related Opportunistic Infections/virology , Herpesvirus 4, Human/physiology , Herpesvirus 8, Human/physiology , Mouth Diseases/virology , Papillomaviridae/physiology , Apoptosis/physiology , Basic-Leucine Zipper Transcription Factors , Carrier Proteins/analysis , Cell Division/physiology , Cell Survival , Cytomegalovirus/physiology , Cytomegalovirus Infections/complications , Epithelial Cells/virology , Epstein-Barr Virus Infections/complications , HIV Infections/complications , Humans , Leukoplakia, Hairy/virology , Lymphoma, AIDS-Related/virology , Mouth Mucosa/virology , Mouth Neoplasms/virology , Oncogene Proteins, Viral/analysis , Papillomavirus Infections/complications , Receptors, Virus/physiology , Repressor Proteins , Saliva/virology , Salivary Gland Diseases/virology , Sarcoma, Kaposi/virology , Signal Transduction/physiology , Stomatitis, Aphthous/virology , Up-Regulation/physiology , Viral Proteins/analysis , Virus Replication , Warts/virology
12.
Oral Dis ; 7(3): 196-9, 2001 May.
Article in English | MEDLINE | ID: mdl-11495197

ABSTRACT

A case of an intraoral myxoid nerve sheath tumour of the dorsum of the tongue in a 73-year-old Caucasian male is reported. This case describes the oldest patient with this pathology to date. Immunoperoxidase staining for neuron-specific enolase (NSE) and epithelial membrane antigen (EMA) expression demonstrated the perineural origin of the lesion.


Subject(s)
Neurothekeoma/pathology , Tongue Neoplasms/pathology , Aged , Humans , Immunoenzyme Techniques , Male , Mucin-1/analysis , Neurothekeoma/enzymology , Phosphopyruvate Hydratase/analysis , Tongue Neoplasms/enzymology
13.
Am J Surg Pathol ; 25(7): 835-45, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11420454

ABSTRACT

We sought to review our experience with salivary mucoepidermoid carcinoma (MEC) over two decades to confirm the validity and reproducibility of histologic grading and to investigate MIB-1 index as a prognosticator. Diagnosis was confirmed on 80 cases, and chart review or patient contact was achieved for 48 patients, with follow-up from 5 to 240 months (median 36 months). Immunohistochemistry with citrate antigen retrieval for MIB-1 was performed on a subset of cases. Kaplan-Meier survival curves were generated for each stage, site, and grade according to our proposed grading system. To address the issue of grading reproducibility, 20 slides were circulated among five observers, without prior discussion; slides were categorized as low-, intermediate-, or high-grade according to one's "own" criteria, and then according to the AFIP criteria proposed by Goode et al.10 Weighted kappa (kappa) estimates were obtained to describe the extent of agreement between pairs of rating. The Wilcoxon signed rank test or the Friedman test as appropriate tested variation across ratings. There was no gender predominance and a wide age range (15-86 years, median 49 years). The two most common sites were parotid and palate. All grade 1 MECs presented as Stage I tumors, and no failures were seen for this category. The local disease failure rates at 75 months for grades 2 and 3 MEC were 30% and 70%, respectively. Tumor grade, stage, and negative margin status all correlated with disease-free survival (DFS) (p = 0.0091, 0.0002, and 0.048, respectively). The MIB index was not found to be predictive of grade. Regarding the reproducibility of grading, the interobserver variation for pathologists using their "own" grading, as expressed by the kappa value, ranged from good agreement (kappa = 0.79) to poor (kappa = 0.27) (average kappa = 0.49). A somewhat better interobserver reproducibility was achieved when the pathologists utilized the standardized AFIP criteria (average kappa = 0.61, range 0.38-0.77). This greater agreement was also reflected in the Friedman test (statistical testing of intraobserver equality), which indicated significant differences in using one's own grading systems (p = 0.0001) but not in applying the AFIP "standardized" grading (p = 0.33). When one's own grading was compared with the AFIP grading, there were 100 pairs of grading "events," with 46 disagreements/100 pairs. For 98% of disagreements, the AFIP grading "downgraded" tumors. This led us to reanalyze a subset of 31 patients for DFS versus grade, for our grading schema compared with the AFIP grading. Although statistical significance was not achieved for this subset, the log rank value revealed a trend for our grading (p = 0.0993) compared with the Goode schema (p = 0.2493). This clinicopathologic analysis confirms the predictive value of tumor staging and three-tiered histologic grading. Our grading exercise confirms that there is significant grading disparity for MEC, even among experienced ENT/oral pathologists. The improved reproducibility obtained when the weighted AFIP criteria were used speaks to the need for an accepted and easily reproducible system. However, these proposed criteria have a tendency to downgrade MEC. Therefore, the addition of other criteria (such as vascular invasion, pattern of tumor infiltration [i.e., small islands and individual cells vs cohesive islands]) is necessary. We propose a modified grading schema, which enhances predictability and provides much needed reproducibility.


Subject(s)
Carcinoma, Mucoepidermoid/pathology , Salivary Gland Neoplasms/pathology , Adolescent , Adult , Aged , Aged, 80 and over , Antigens, Nuclear , Carcinoma, Mucoepidermoid/metabolism , Female , Humans , Immunohistochemistry , Ki-67 Antigen , Male , Middle Aged , Nuclear Proteins/metabolism , Reproducibility of Results , Salivary Gland Neoplasms/metabolism , Survival Analysis
14.
Planta ; 212(3): 460-5, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11289612

ABSTRACT

The sesquiterpenoid artemisinin, isolated these from the plant Artemisia annua L., and its semi-synthetic derivatives are a new and very effective group of antimalarial drugs. A branch point in the biosynthesis of this compound is the cyclisation of the ubiquitous precursor farnesyl diphosphate into the first specific precursor of artemisinin, namely amorpha-4,11-diene. Here we describe the isolation of a cDNA clone encoding amorpha-4,11-diene synthase. The deduced amino acid sequence exhibits the highest identity (50%) with a putative sesquiterpene cyclase of A. annua. When expressed in Escherichia coli, the recombinant enzyme catalyses the formation of amorpha-4,11-diene from farnesyl diphosphate. Introduction of the gene into tobacco (Nicotiana tabacum L.) resulted in the expression of an active enzyme and the accumulation of amorpha-4,11-diene ranging from 0.2 to 1.7 ng per g fresh weight.


Subject(s)
Alkyl and Aryl Transferases/genetics , Antimalarials , Artemisinins , Escherichia coli/enzymology , Nicotiana/enzymology , Plants, Toxic , Sesquiterpenes , Alkyl and Aryl Transferases/chemistry , Alkyl and Aryl Transferases/metabolism , Amino Acid Sequence , Antimalarials/isolation & purification , Artemisia/chemistry , Artemisia/genetics , Base Sequence , Cells, Cultured , Cloning, Molecular , DNA, Complementary/genetics , DNA, Complementary/isolation & purification , DNA, Complementary/metabolism , Electrophoresis, Polyacrylamide Gel , Escherichia coli/genetics , Gas Chromatography-Mass Spectrometry , Gene Expression , Molecular Sequence Data , Plants, Medicinal , Polymerase Chain Reaction , RNA/isolation & purification , Sesquiterpenes/isolation & purification , Nicotiana/genetics
15.
Mol Plant Microbe Interact ; 14(4): 460-70, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11310733

ABSTRACT

The phytopathogenic fungus Alternaria alternata f. sp. lycopersici produces AAL toxins required to colonize susceptible tomato (Lycopersicon esculentum) plants. AAL toxins and fumonisins of the unrelated fungus Fusarium moniliforme are sphinganine-analog mycotoxins (SAMs), which are toxic for some plant species and mammalian cell lines. Insensitivity of tomato to SAMs is determined by the Alternaria stem canker gene 1 (Asc-1), and sensitivity is associated with a mutated Asc-1. We show that SAM-sensitive species occur at a low frequency in the Nicotiana genus and that candidate Asc-1 homologs are still present in those species. In Nicotiana spp., SAM-sensitivity and insensitivity also is mediated by a single codominant locus, suggesting that SAM-sensitive genotypes are host for A. alternata f. sp. lycopersici. Nicotiana umbratica plants homozygous for SAM-sensitivity are indeed susceptible to A. alternata f. sp. lycopersici. In contrast, SAM-sensitive genotypes of Nicotiana spegazzinii, Nicotiana acuminata var. acuminata, Nicotiana bonariensis, and Nicotiana langsdorffii are resistant to A. alternata f. sp. lycopersici infection concomitant with localized cell death. Additional (nonhost) resistance mechanisms to A. alternata f. sp. lycopersici that are not based on an insensitivity to SAMs are proposed to be present in Nicotiana species.


Subject(s)
Ascomycota/physiology , Mycotoxins/toxicity , Nicotiana/microbiology , Plants, Toxic , Solanum lycopersicum/microbiology , Nicotiana/drug effects
16.
Electrophoresis ; 22(19): 4035-52, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11824628

ABSTRACT

Proteome analysis requires fast methods with high separation efficiencies in order to screen the various cell and tissue types for their proteome expression and monitor the effect of environmental conditions and time on this expression. The established two-dimensional gel electrophoresis (2-DE) is by far too slow for a consequential screening. Moreover, it is not precise enough to observe changes in protein concentrations. There are various approaches that promise faster, automated proteome analysis. This article concentrates on capillary (CT isoelectric focusing coupled to mass spectrometry (CIEF-MSn) and preparative IEF followed by size-exclusion chromatography, hyphenated with MS (PIEF-SEC-MS). These two approaches provide a similar separation pattern as the established 2-DE technique and therefore allow for the continued use of data based on this traditional approach. Their performances have been discussed and compared to 2-DE, evaluating 169 recent articles. Data on analysis time, automation, the detection limit, quantitation, peak capacity, mass and pI accuracy, as well as on the required sample amount are compared in a table.


Subject(s)
Electrophoresis, Gel, Two-Dimensional/methods , Proteome , Spectrum Analysis/methods , Automation , Reproducibility of Results
17.
Mol Plant Pathol ; 2(4): 229-39, 2001 Jul 01.
Article in English | MEDLINE | ID: mdl-20573011

ABSTRACT

Summary Host-selective toxins are known determinants of compatibility in plant-fungus interactions and provide a powerful model for understanding the specificity of these associations. The identification of genes required for toxin biosynthesis has shown that the genes are unique to the toxin producing species and are clustered in complex loci. These loci may have been acquired by horizontal gene transfer. Many, if not all, host-selective toxins act by disrupting biochemical processes and in several cases the resulting cell death has the characteristics of programmed cell death. This ability to make dead tissue from living has enabled these facultative saprophytic fungi to become plant pathogens.

18.
Proc Natl Acad Sci U S A ; 97(9): 4961-6, 2000 Apr 25.
Article in English | MEDLINE | ID: mdl-10781105

ABSTRACT

The phytopathogenic fungus Alternaria alternata f. sp. lycopersici (AAL) produces toxins that are essential for pathogenicity of the fungus on tomato (Lycopersicon esculentum). AAL toxins and fumonisins of the unrelated fungus Fusarium moniliforme are sphinganine-analog mycotoxins (SAMs), which cause inhibition of sphingolipid biosynthesis in vitro and are toxic for some plant species and mammalian cell lines. Sphingolipids can be determinants in the proliferation or death of cells. We investigated the tomato Alternaria stem canker (Asc) locus, which mediates resistance to SAM-induced apoptosis. Until now, mycotoxin resistance of plants has been associated with detoxification and altered affinity or absence of the toxin targets. Here we show that SAM resistance of tomato is determined by Asc-1, a gene homologous to the yeast longevity assurance gene LAG1 and that susceptibility is associated with a mutant Asc-1. Because both sphingolipid synthesis and LAG1 facilitate endocytosis of glycosylphosphatidylinositol-anchored proteins in yeast, we propose a role for Asc-1 in a salvage mechanism of sphingolipid-depleted plant cells.


Subject(s)
Alternaria/pathogenicity , Carboxylic Acids/toxicity , Fumonisins , Fungal Proteins/genetics , Genes, Plant , Membrane Proteins/genetics , Mycotoxins/toxicity , Saccharomyces cerevisiae Proteins , Solanum lycopersicum/genetics , Solanum lycopersicum/microbiology , Adaptor Proteins, Signal Transducing , Amino Acid Sequence , Apoptosis , Cell Death , Cell Division , Fungal Proteins/chemistry , GTP-Binding Proteins , Solanum lycopersicum/drug effects , Membrane Proteins/chemistry , Molecular Sequence Data , Plant Diseases/genetics , Sequence Alignment , Sequence Homology, Amino Acid , Sphingolipids/biosynthesis , Sphingolipids/metabolism , Sphingosine/analogs & derivatives , Sphingosine/toxicity
19.
Plant J ; 20(3): 279-88, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10571888

ABSTRACT

The tomato Cf-4 and Cf-9 genes confer resistance to the leaf mould pathogen Cladosporium fulvum and map at a complex locus on the short arm of chromosome 1. It was previously shown that the gene encoding Cf-4, which recognizes the Avr4 avirulence determinant, is one of five tandemly duplicated homologous genes (Hcr9-4s) at this locus. Cf-4 was identified by molecular analysis of rare Cf-4/Cf-9 disease-sensitive recombinants and by complementation analysis. The analysis did not exclude the possibility that an additional gene(s) located distal to Cf-4 may also confer resistance to C. fulvum. We demonstrate that a number of Dissociation-tagged Cf-4 mutants, identified on the basis of their insensitivity to Avr4, are still resistant to infection by C. fulvum race 5. Molecular analysis of 16 Cf-4 mutants, most of which have small chromosomal deletions in this region, suggested the additional resistance specificity is encoded by Hcr9-4E. Hcr9-4E recognizes a novel C. fulvum avirulence determinant that we have designated Avr4E.

20.
Mol Gen Genet ; 261(1): 50-7, 1999 Feb.
Article in English | MEDLINE | ID: mdl-10071209

ABSTRACT

The Alternaria stem canker disease of tomato is caused by the necrotrophic fungal pathogen Alternaria alternata f. sp. lycopersici (AAL). The fungus produces AAL toxins that kill the plant tissue. Resistance to the fungus segregates as a single locus, called Asc, and has been genetically mapped on chromosome 3 of tomato. We describe here the establishment of a 1383-kb YAC contig covering the Asc locus and a series of plants selected for recombination events around the Asc locus. It was shown that the YAC contig corresponds to a genetic distance of at least 11.2 cM. Thus, the recombination rate in the Asc region is six times higher (123 kb/cM) than the average for the tomato genome. Furthermore, the Asc locus could be localised to a 91-kb fragment, thus paving the way for the cloning and identification of the Asc gene(s) by complementation.


Subject(s)
Genes, Plant/genetics , Plant Diseases/genetics , Solanum lycopersicum/genetics , Alternaria/pathogenicity , Chromosomes, Artificial, Yeast , Contig Mapping , Crosses, Genetic , DNA, Plant/analysis , DNA, Plant/genetics , Solanum lycopersicum/microbiology , Physical Chromosome Mapping , Plant Diseases/microbiology , Recombination, Genetic
SELECTION OF CITATIONS
SEARCH DETAIL
...