Mining disease-resistance genes in roses: functional and molecular characterization of the rdr1 locus

The interaction of roses with the leaf spot pathogen Diplocarpon rosae (the cause of black spot on roses) is an interesting pathosystem because it involves a long-lived woody perennial, with life history traits very different from most model plants, and a hemibiotrophic pathogen with moderate levels of gene flow. Here we present data on the molecular structure of the first monogenic dominant resistance gene from roses, Rdr1, directed against one isolate of D. rosae. Complete sequencing of the locus carrying the Rdr1 gene resulted in a sequence of 265,477 bp with a cluster of nine highly related TIR-NBS-LRR (TNL) candidate genes. After sequencing revealed candidate genes for Rdr1, we implemented a gene expression analysis and selected five genes out of the nine TNLs. We then silenced the whole TNL gene family using RNAi (Rdr1-RNAi) constructed from the most conserved sequence region and demonstrated a loss of resistance in the normally resistant genotype. To identify the functional TNL gene, we further screened the five TNL candidate genes with a transient leaf infiltration assay. The transient expression assay indicated a single TNL gene (muRdr1H), partially restoring resistance in the susceptible genotype. Rdr1 was found to localize within the muRdr1 gene family; the genes within this locus contain characteristic motifs of active TNL genes and belong to a young cluster of R genes. The transient leaf assay can be used to further analyze the rose black spot interaction and its evolution, extending the analyses to additional R genes and to additional pathogenic types of the pathogen.

Vitamin B12-responsive severe leukoencephalopathy and autonomic dysfunction in a patient with "normal" serum B12 levels

Leukoencephalopathy and autonomic dysfunction have been described in individuals with very low serum B(12) levels (<200 pg/ml), in addition to psychiatric changes, neuropathy, dementia and subacute combined degeneration. Elevated homocysteine and methylmalonic acid levels are considered more sensitive and specific for evaluating truly functional B(12) deficiency. A previously healthy 62-year-old woman developed depression and cognitive deficits with autonomic dysfunction that progressed over the course of 5 years. The patient had progressive, severe leukoencephalopathy on multiple MRI scans over 5 years. Serum B(12) levels ranged from 267 to 447 pg/ml. Homocysteine and methylmalonic acid levels were normal. Testing for antibody to intrinsic factor was positive, consistent with pernicious anaemia. After treatment with intramuscular B(12) injections (1000 μg daily for 1 week, weekly for 6 weeks, then monthly), she made a remarkable clinical recovery but remained amnesic for major events of the last 5 years. Repeat MRI showed partial resolution of white matter changes. Serum B(12), homocysteine and methylmalonic acid levels are unreliable predictors of B(12)-responsive neurologic disorders, and should be thoroughly investigated and presumptively treated in patients with unexplained leukoencephalopathy because even long-standing deficits may be reversible.

[Non-compaction cardiomyopathy: A rare echocardiographic diagnosis]

HISTORY AND CLINICAL FINDINGS

A 55-year-old woman was referred to our hospital with signs of cerebral ischaemia i. e. dysarthria and weakness of the buccal branch of the facial nerve. Additionally the patient reported symptoms of heart failure NYHA class II. Six months earlier the patient also had visual disturbances. Magnetic resonance imaging (MRI) had shown ischaemic lesions.

INVESTIGATIONS

A recent MRI confirmed the suspected diagnosis of ischaemia in the territory supplied by the left middle cerebral artery. The echocardiography was characterized by a reduced left ventricular ejection fraction (25 %) due to isolated ventricular non-compaction (IVNC).

TREATMENT AND COURSE

The patient was treated with a combination therapy including ACE-inhibitors and diuretics. An oral anticoagulation was recommended as secondary prophylaxis. At the time of discharge the patient had no residual neurological deficits.

CONCLUSION

Isolated ventricular non-compaction is a rare type of cardiomyopathy. Possible manifestations include systemic embolic events, arrhythmias and heart failure. Echocardiography is the investigation of choice in identifying characteristic changes.

Molecular markers from a BAC contig spanning the Rdr1 locus: a tool for marker-assisted selection in roses

We constructed a BAC contig of about 300 kb spanning the Rdr1 locus for black spot resistance in Rosa multiflora hybrids, using a new BIBAC library from DNA of this species. From this contig, we developed broadly applicable simple sequence repeat (SSR) markers tightly linked to Rdr1, which are suitable for genetic analyses and marker-assisted selection in roses. As a source for the high molecular weight DNA, we chose the homozygous resistant R. multiflora hybrid 88/124-46. For the assembly of the BAC contig, we made use of molecular markers derived from a previously established R. rugosa contig. In order to increase the resolution for fine mapping, the size of the population was increased to 974 plants. The genomic region spanning Rdr1 is now genetically restricted to 0.2 cM, corresponding to a physical distance of about 300 kb. One single-stranded conformational polymorphism (SSCP) and one SSR marker cosegregate with the Rdr1-mediated black spot resistance, while one SSR and several cleaved amplified polymorphic sequence or SSCP markers are very tightly linked with one to three recombinants among the 974 plants. The benefits of the molecular markers developed from the R. multiflora contig for the genetic analysis of roses and the integration of rose genetic maps are discussed.

Second consensus statement on the diagnosis of multiple system atrophy

BACKGROUND

A consensus conference on multiple system atrophy (MSA) in 1998 established criteria for diagnosis that have been accepted widely. Since then, clinical, laboratory, neuropathologic, and imaging studies have advanced the field, requiring a fresh evaluation of diagnostic criteria. We held a second consensus conference in 2007 and present the results here.

METHODS

Experts in the clinical, neuropathologic, and imaging aspects of MSA were invited to participate in a 2-day consensus conference. Participants were divided into five groups, consisting of specialists in the parkinsonian, cerebellar, autonomic, neuropathologic, and imaging aspects of the disorder. Each group independently wrote diagnostic criteria for its area of expertise in advance of the meeting. These criteria were discussed and reconciled during the meeting using consensus methodology.

RESULTS

The new criteria retain the diagnostic categories of MSA with predominant parkinsonism and MSA with predominant cerebellar ataxia to designate the predominant motor features and also retain the designations of definite, probable, and possible MSA. Definite MSA requires neuropathologic demonstration of CNS alpha-synuclein-positive glial cytoplasmic inclusions with neurodegenerative changes in striatonigral or olivopontocerebellar structures. Probable MSA requires a sporadic, progressive adult-onset disorder including rigorously defined autonomic failure and poorly levodopa-responsive parkinsonism or cerebellar ataxia. Possible MSA requires a sporadic, progressive adult-onset disease including parkinsonism or cerebellar ataxia and at least one feature suggesting autonomic dysfunction plus one other feature that may be a clinical or a neuroimaging abnormality.

CONCLUSIONS

These new criteria have simplified the previous criteria, have incorporated current knowledge, and are expected to enhance future assessments of the disease.

Cytogenetic patterns in multiple myeloma after a phase of preceding MGUS

BACKGROUND

Presenting the same histological diagnosis, multiple myeloma (MM) shows a large genomic variety, resulting in variable times of overall survival.

MATERIALS AND METHODS

To investigate major cytogenetic categories (any 14q-translocation, t(11;14), t(4;14), 13q-deletions, 17p-deletions) and their clinical consequences in MM after a pre-existing monoclonal gammopathy (MM post-MGUS), we performed a comparative analysis of 41 patients with MM post-MGUS and 287 patients with unknown prior history MM (U-MM).

RESULTS

In MM post-MGUS, a t(11;14) was found to be more frequent than in U-MM (24% vs. 14%) and it was associated with significantly shortened survival (24 months vs. 70 months in U-MM; P = 0.01). MM post-MGUS was further characterized by a higher frequency of 13q-deletions only (absence of all other specific abnormalities; 28% vs. 12% in U-MM; P = 0.02). A 13q-deletion only was an indicator of long survival in MM post-MGUS (median not yet reached) as opposed to U-MM (median survival, 29 months; P = 0.001). 17p-deletions were infrequent in MM post-MGUS (3% vs. 16% in U-MM; P = 0.04). Survival times for patients with t(4;14) and/or 17p-deletions and other abnormalities were similar in both MM patient cohorts.

CONCLUSIONS

Our data suggest that t(11;14) and 13q-deletions have distinct prognostic implications in the context of MM post-MGUS.

Chromosomal abnormalities of young multiple myeloma patients (<45 yr) are not different from those of other age groups and are independent of stage according to the International Staging System

Little is known about tumor-related prognostic factors, in particular specific chromosomal abnormalities, in young patients with multiple myeloma (MM). We therefore investigated the chromosomal pattern by interphase fluorescence in situ hybridization (chromosomes 13q14, 14q32-translocations, chromosomes associated with hyperdiploidy) in 38 young patients with MM (age <45 yr) and compared the results with those observed in 69 patients with intermediate age (45-70 yr) and 64 elderly patients (age >70 yr). All chromosomal patterns were not significantly different between the three age cohorts. Similarly, standard MM parameters were equally distributed between these MM patient populations. However, survival by the International Staging System (ISS) for MM revealed marked differences between stage I/II (median survival not yet reached) and stage III (23.4 months; P < 0.0003) among young MM patients. A significant survival difference between ISS-stage I/II and ISS-stage III patients was also noted in the intermediate age group (median 65.4 months vs. 24.6 months; P = 0.0009). However, this difference disappeared among elderly MM patients (39.6 months in ISS-stage I/II vs. 32 months in ISS-stage III patients; P = 0.94), but it was unrelated to the cytogenetic pattern. Our results indicate that MM in young patients does not represent a distinct biologic entity, and that short survival of younger MM patients at ISS-stage III is independent of the molecular cytogenetic pattern.

Bortezomib in relapsed multiple myeloma: response rates and duration of response are independent of a chromosome 13q-deletion

Studies of bortezomib in patients with relapsed multiple myeloma (MM) suggested that bortezomib may be active even in the presence of adverse prognostic factors. We therefore evaluated 62 patients with relapsed/refractory MM who were treated with single-agent bortezomib, and addressed the question whether or not the negative prognostic impact of unfavorable cytogenetic abnormalities may be overcome by bortezomib. By interphase fluorescence in situ hybridization (FISH), a deletion of chromosome 13q14 [del(13q14)] was present in 33 patients (53%). Overall response rates to bortezomib were similar in patients with and without del(13q14) (45 versus 55%; P=0.66), and rates of complete remission (CR) near CR were also not different between the two patient populations (18 versus 14%). Three patients had a t(4;14)(p16;q32) in addition to del(13q14), and all of them had a >50% paraprotein reduction. Median duration of response was 12.3 months in patients with del(13q14) compared with 9.3 months in patients with normal 13q-status (P=0.25), and survival was also not different between the two patient populations. Patients not benefiting from single-agent bortezomib were characterized by the combined presence of a del(13q14) and low serum albumin (median survival 4.6 months). Our results provide evidence for remarkable activity of bortezomib in MM with del(13q14). Patients who do not respond to bortezomib and consecutively have short time to treatment failure and overall survival can be identified by low serum albumin in addition to del(13q14) and should be considered for bortezomib combinations.

The discovery of the pressor effect of DOPS and its blunting by decarboxylase inhibitors

In the 1950s it was found that an artificial aminoacid, 3,4-threo-dihydroxyphenylserine (DOPS), was converted to norepinephrine (NE) in a single step by the enzyme L-aromatic amino acid decarboxylase (AADC), bypassing the need for the rate limiting enzyme dopamine beta hydroxylase. Trying to replicate the success of dihydroxyphenylalanine (DOPA) in the treatment of Parkinson disease, treatment with DOPS was attempted in patients with autonomic failure who have impaired NE release. DOPS improved orthostatic hypotension in patients with familial amyloid polyneuropathy, congenital deficiency of dopamine beta hydroxylase, pure autonomic failure and multiple system atrophy. DOPS pressor effect is due to its conversion to NE outside the central nervous system because concomitant administration of carbidopa, an inhibitor of AADC that does not cross the blood-brain barrier, blunted both the increase in plasma NE and the pressor response. DOPS pressor response is not dependent on intact sympathetic terminals because its conversion to NE also occurs in non-neuronal tissues.

Powdery mildew resistance in roses: QTL mapping in different environments using selective genotyping

Podosphaera pannosa, the causal agent of rose powdery mildew, hampers the production of cut roses throughout the world. A major tool to control this disease is the use of resistant plant material. Single resistance genes, like Rpp1, may be overcome within a few years by high risk pathogens like powdery mildews. Durable resistance could be achieved using quantitative resistances. Here we describe mapping of QTLs for resistance to P. pannosa in six different environments (artificial and natural infections in the greenhouse over 3 years and natural infections in the field over 2 years). AFLPs, RGAs and other marker types were used to construct an integrated linkage map for the diploid population 97/7 containing 233 markers. In a selective genotyping procedure, marker segregation was analysed for 170 of the up to 270 phenotyped individuals. We identified seven linkage groups with an average length of 60 cM, corresponding to seven rose chromosomes in the haploid set. Using an LOD significance threshold of 3.9 we detected a total of 28 QTLs for the nine powdery mildew disease scores under analysis. Using the data from artificial inoculations with powdery mildew race 9, three resistance QTLs explaining about 84% of the variability were mapped. Twelve and 15 QTLs were detected for resistance to naturally occurring infections in the greenhouse and in the field, respectively, over several years.

Marked activity of bortezomib, rituximab, and dexamethasone (BORID) in heavily pretreated patients with mantle cell lymphoma

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Background: Bortezomib (B) belongs to a new class of anti-cancer agents, the proteasome inhibitors, and has documented activity in multiple myeloma and mantle cell lymphoma (MCL). Preclinical studies suggest that B has synergistic activity with rituximab (R), which provides a rationale for the exploration of treatment combinations. Methods: We have initiated a phase II study in relapsed/chemotherapy refractory MCL to evaluate the activity and safety of B in combination with R and dexamethasone (BORID). A treatment cycle consists of B at 1.3 mg/m2 administered on days 1, 4, 8, and 11, R at 375 mg/m2 administered on day 1, and dexamethasone 40 mg orally on days 1 to 4. Cycles are repeated every 3 weeks for a total of 6 treatment cycles. Patients (pts) with progressive MCL after at least one prior line of therapy (including CHOP or a CHOP-like regimen) are eligible. Results: Up to now, we have enrolled 10 pts (median age, 69 years; range, 48 to 75 years) after a median of 3 lines of prior therapies (range, 1 to 6) including R in 8 pts, high-dose therapy in 3 pts, and thalidomide in 5 pts. Median time between start of frontline therapy and study inclusion was 43 months (range, 11 to 98 months). Severe adverse events (> grade II) included infections (herpes zoster in 2 pts, bacterial pneumonia, mucosal candidiasis), peripheral neuropathy (3 pts), fatigue (2 pts) and vasculitic skin infiltrates in 3 pts. Thrombopenia (< 50 G/L) occured in 2 pts. All adverse events were managable by standard means of supportive care and prolongation of the treatment interval between cycles. Of 8 pts evaluable for efficacy, 7 have achieved a response (3 CR, 4 PR), and 1 pt experienced stable disease. Pts in CR were also negative for disease activity by PET scanning. Skin infiltrates (histologically proven T-cell infiltrates) preceded achievement of CR in 2 pts. 6 of 6 pts are still progression-free at 6 months after treatment initiation. Recruitment of patients is ongoing, and updated results will be presented. Conclusions: Data obtained thus far indicate that BORID has promising activitiy and managable toxicity in patients with heavily pretreated MCL, and development of a vasculitic rash may be an early indicator of a favorable response.

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