Successful intergeneric transfer of a major apple scab resistance gene (Rvi6) from apple to pear and precise comparison of the downstream molecular mechanisms of this resistance in both species.

BACKGROUND: Scab is the most important fungal disease of apple and pear. Apple (Malus x domestica Borkh.) and European pear (Pyrus communis L.) are genetically related but they are hosts of two different fungal species: Venturia inaequalis for apple and V. pyrina for European pear. The apple/V. inaequalis pathosystem is quite well known, whereas knowledge about the pear/V. pyrina pathosystem is still limited. The aim of our study was to analyse the mode of action of a major resistance gene of apple (Rvi6) in transgenic apple and pear plants interacting with the two scab species (V. inaequalis and V. pyrina), in order to determine the degree of functional transferability between the two pathosystems. RESULTS: Transgenic pear clones constitutively expressing the Rvi6 gene from apple were compared to a scab transgenic apple clone carrying the same construct. After inoculation in greenhouse with V. pyrina, strong defense reactions and very limited sporulation were observed on all transgenic pear clones tested. Microscopic observations revealed frequent aborted conidiophores in the Rvi6 transgenic pear / V. pyrina interaction. The macro- and microscopic observations were very comparable to the Rvi6 apple / V. inaequalis interaction. However, this resistance in pear proved variable according to the strain of V. pyrina, and one of the strains tested overcame the resistance of most of the transgenic pear clones. Comparative transcriptomic analyses of apple and pear resistant interactions with V. inaequalis and V. pyrina, respectively, revealed different cascades of molecular mechanisms downstream of the pathogen recognition by Rvi6 in the two species. Signal transduction was triggered in both species with calcium (and G-proteins in pear) and interconnected hormonal signaling (jasmonic acid in pear, auxins in apple and brassinosteroids in both species), without involvement of salicylic acid. This led to the induction of defense responses such as a remodeling of primary and secondary cell wall, lipids biosynthesis (galactolipids in apple and cutin and cuticular waxes in pear), systemic acquired resistance signal generation (in apple) or perception in distal tissues (in pear), and the biosynthesis of phenylpropanoids (flavonoids in apple but also lignin in pear). CONCLUSION: This study is the first example of a successful intergeneric transfer of a resistance gene among Rosaceae, with a resistance gene functioning towards another species of pathogen.

Membrane-targeted HrpNEa can modulate apple defense gene expression.

Fire blight caused by Erwinia amylovora is the major bacterial disease of tribe Maleae, including apple. Among the proteins secreted by this bacterium, HrpNEa, also called harpin, is known to induce hypersensitive response in nonhost plants and to form amyloid oligomers leading to pore opening in the plasma membrane and alteration of membrane homeostasis. To better understand the physiological effects of HrpNEa in the host plant, we produced transgenic apple plants expressing HrpNEa with or without a secretion signal peptide (SP). HrpNEa expressed with a SP was found to be associated within the membrane fraction, in accordance with amyloidogenic properties and the presence of transmembrane domains revealed by in silico analysis. Expression analysis of 28 apple defense-related genes revealed gene modulations in the transgenic line expressing membrane-targeted HrpNEa. While apple transgenic trees displaying a high constitutive expression level of SP-HrpNEa showed a slight reduction of infection frequency after E. amylovora inoculation, there was no decrease in the disease severity. Thus HrpNEa seems to act as an elicitor of host defenses, when localized in the host membrane.

[Intensity modulation in breast radiotherapy: development of an innovative field-in-field technique at Institut Gustave-Roussy]. / Modulation d'intensité en radiothérapie mammaire : développement d'une méthode innovante de champ dans le champ à l'institut Gustave-Roussy.

PURPOSE: To assess the potential dosimetric gain of presegmentation modulated radiotherapy (OAPS, DosiSoft™) of breast, compared to routine 3D conformal radiotherapy. PATIENTS AND METHODS: Twenty patients treated with conservative surgery for breast cancer (9 right and 11 left sided) with various breast volume (median 537 cm(3); range [100-1049 cm(3)]) have been selected. For each patient, we have delineated a breast volume and a compensation volume (target volumes), as well as organs at risk (lungs and heart). Two treatment plans have been generated: one using the routine 3D conformal technique and the other with the presegmentation algorithm of DosiSoft™ (OAPS). The dose distribution were analyzed using the conformity index for target volumes, mean dose and V30 Gy for the heart, and mean dose, V20 Gy and V30 Gy for lungs. RESULTS: Over the 20 patients, the conformity index increased from 0.897 with routine technique to 0.978 with OAPS (P<0,0001). For heart and lung, OAPS decreased irradiation (mean cardiac dose 1,3 vs 1,6 Gy [P<0,0001] and pulmonary V20 Gy 6,6 vs 7,1 [P<0,0001]). CONCLUSION: OAPS (DosiSoft™) is an original method of segmentation of breast. It is automatic, fast and easy, and is able to increase the conformity index, while sparing organ at risk.

ARCHIPELAGO: a dedicated resource for exploiting past, present, and future genomic data on disease resistance regulation in rice.

Large amounts of expression data dealing with biotic stresses in rice have been produced in the past 5 years. Here, we extensively review approximately 70 publications and gather together information on more than 2,500 genes of the rice defense arsenal. This information was integrated into the OryGenesDB database. Several genes (e.g., metallothioneins and PBZ1) appear to be hallmarks of rice-pathogen interactions. Cross-referencing this information with the rice kinome highlighted some defense genes and kinases as possible central nodes of regulation. Cross referencing defense gene expression and quantitative trait loci (QTL) information identified some candidate genes for QTL. Overall, pathogenesis-related genes and disease regulators were found to be statistically associated with disease QTL. At the genomic level, we observed that some regions are richer than others and that some chromosomes (e.g., 11 and 12), which contain a lot of resistance gene analogs, have a low content of defense genes. Finally, we show that classical defense genes and defense-related genes such as resistance genes are preferentially organized in clusters. These clusters are not always coregulated and individual paralogs can show specific expression patterns. Thus, the rice defense arsenal has an ARCHIPELAGO-like genome structure at the macro and micro level. This resource opens new possibilities for marker-assisted selection and QTL cloning.

Early and specific gene expression triggered by rice resistance gene Pi33 in response to infection by ACE1 avirulent blast fungus.

* Our view of genes involved in rice disease resistance is far from complete. Here we used a gene-for-gene relationship corresponding to the interaction between atypical avirulence gene ACE1 from Magnaporthe grisea and rice resistance gene Pi33 to better characterize early rice defence responses induced during such interaction. * Rice genes differentially expressed during early stages of Pi33/ACE1 interaction were identified using DNA chip-based differential hybridization and QRT-PCR survey of the expression of known and putative regulators of disease resistance. * One hundred genes were identified as induced or repressed during rice defence response, 80% of which are novel, including resistance gene analogues. Pi33/ACE1 interaction also triggered the up-regulation of classical PR defence genes and a massive down-regulation of chlorophyll a/b binding genes. Most of these differentially expressed genes were induced or repressed earlier in Pi33/ACE1 interaction than in the gene-for-gene interaction involving Nipponbare resistant cultivar. * Besides demonstrating that an ACE1/Pi33 interaction induced classical and specific expression patterns, this work provides a list of new genes likely to be involved in rice disease resistance.

The 1986 dengue and dengue hemorrhagic fever epidemic in Puerto Rico: epidemiologic and clinical observations.

In 1986 Puerto Rico experienced its eleventh dengue outbreak of this century, but the first with simultaneous transmission of three dengue virus serotypes, and the first with significant numbers of severe and fatal hemorrhagic disease. Overall, 10,659 cases were reported; 1,257 cases were laboratory confirmed as having current or recent dengue infection. Dengue 4 (DEN-4) was the predominant serotype (160/363 isolates, 44%) followed by dengue 1 (DEN-1) with 134 isolates (37%) and dengue 2 (DEN-2), 69 isolates (19%). Transmission peaked during September, but large numbers of cases occurred through November. Seventy-one (91%) of Puerto Rico's 78 municipalities had laboratory-confirmed cases. Fifty-one percent of all confirmed cases occurred in metropolitan San Juan. Most cases presented clinically as classical dengue fever, but 37% of all confirmed cases were reported to have developed some type of hemorrhagic manifestation, and 6% reported hematemesis. In addition, 29 laboratory confirmed cases met the WHO case definition for dengue hemorrhagic fever, 3 of which were fatal. Among the 29 laboratory-confirmed cases of dengue hemorrhagic fever/ dengue shook syndrome, virus was isolated from 12; one DEN-1, three DEN-2, and eight DEN-4. Among laboratory confirmed cases, infants less than one year of age were at greater risk of developing dengue hemorrhagic fever/ dengue shook syndrome, hematemesis and any reported hemorrhage than were the other age groups evaluated.

The 1986 dengue and dengue hemorrhagic fever epidemic in Puerto Rico: epidemiologic and clinical observations

In 1986 Puerto Rico experienced its eleventh dengue outbreak of this century, but the first with simultaneous transmission of three dengue virus serotypes, and the first with significant numbers of severe and fatal hemorrhagic disease. Overall, 10,659 cases were reported; 1,257 cases were laboratory confirmed as having current or recent dengue infection. Dengue 4 (DEN-4) was the predominant serotype (160/363 isolates, 44 percent) followed by dengue 1 (DEN-1) with 134 isolates (37 percent) and dengue 2 (DEN-2), 69 isolates (19 percent). Transmission peaked during September, but large numbers of cases occurred through November. Seventy-one (91 percent) of Puerto Rico's 78 municipalities had laboratory-confirmed cases. Fifty-one percent of all confirmed cases occurred in metropolitan San Juan. Most cases presented clinically as classical dengue fever, but 37 percent of all confirmed cases were reported to have developed some type of hemorrhagic manifestation, and 6 percent reported hematemesis. In addition, 29 laboratory confirmed cases met the WHO case definition for dengue hemorrhagic fever, 3 of which were fatal. Among the 29 laboratory-confirmed cases of dengue hemorrhagic fever/ dengue shook syndrome, virus was isolated from 12; one DEN-1, three DEN-2, and eight DEN-4. Among laboratory confirmed cases, infants less than one year of age were at greater risk of developing dengue hemorrhagic fever/ dengue shook syndrome, hematemesis and any reported hemorrhage than were the other age groups evaluated

An integrated target sequence and signal amplification assay, reverse transcriptase-PCR-enzyme-linked immunosorbent assay, to detect and characterize flaviviruses.

We previously described a reverse transcriptase-PCR using flavivirus genus-conserved and virus species-specific amplimers (D. W. Trent and G. J. Chang, p. 355-371, in Y. Becker and C. Darai; ed., Frontiers of Virology, vol. 1, 1992). Target amplification was improved by redesigning the amplimers, and a sensitive enzyme-linked immunosorbent assay (ELISA) technique has been developed to detect amplified digoxigenin (DIG)-modified DNA. A single biotin motif and multiple DIG motifs were incorporated into each amplicon, which permitted amplicon capture by a biotin-streptavidin interaction and detection with DIG-specific antiserum in a colorimetric ELISA. We evaluated the utility of this assay for detecting St. Louis encephalitis (SLE) viral RNA in infected mosquitoes and dengue viral RNA in human serum specimens. The reverse transcriptase-PCR-ELISA was as sensitive as isolation of SLE virus by cell culture in detecting SLE viral RNA in infected mosquitoes. The test was 89% specific and 95 to 100% sensitive for identification of dengue viral RNA in serum specimens compared with isolation of virus by Aedes albopictus C6/36 cell culture and identification by the indirect immunofluorescence assay.

Failure of dengue viruses to replicate in Culex quinquefasciatus (Diptera: Culicidae).

Culex quinquefasciatus (Say) and Aedes aegypti (L.) were parenterally infected with dengue viruses and virus replication was monitored at intervals after infection in each species. Dengue viruses replicated rapidly in Ae. aegypti, reaching a peak titer of 10(6)-10(7) mosquito infectious dose 50 (MID50) per mosquito. In Cx. quinquefasciatus, however, dengue virus replication did not occur. We conclude that this mosquito species is refractory to infection with dengue viruses and, therefore, does not serve as a vector in nature.