Synthesis of full-length transcripts of beet western yellows virus RNA: messenger properties and biological activity in protoplasts

Full-length cDNA of beet western yellows virus genomic RNA has been cloned behind the bacteriophage T7 RNA polymerase promoter of the transcription vector BS(-). The in vitro run-off transcription product obtained in the presence of T7 RNA polymerase and m7GpppG cap has the same messenger properties as natural viral RNA in in vitro translation systems. The full-length transcript was also able to infect Chenopodium quinoa protoplasts inoculated by electroporation. Infection could be followed by the appearance of viral coat protein in the inoculated protoplasts and the de novo synthesis of viral RNA. Site-directed mutagenesis experiments revealed that expression of beet western yellows virus open reading frame 1 and the C-terminal portion of open reading frame 6 were not required for infection of protoplasts. Additional experiments with these mutants and mutants in the other viral open reading frames should provide information concerning the requirements for beet western yellows virus replication and, ultimately, the role of virus genes in other important steps in the virus infection cycle, such as aphid transmission.

Efficient cell-to-cell movement of beet necrotic yellow vein virus requires 3' proximal genes located on RNA 2

RNA 2 of beet necrotic yellow vein virus (BNYVV) carries six open reading frames. The four 3' proximal frames encode the proteins P42, P13, P15, and P14. The first three species present homologies to proteins encoded by three overlapping open reading frames (the triple gene block) in potexviruses, carlaviruses, and barley stripe mosaic virus. P14 does not display homology with other known plant viral proteins. The functions of P42, P13, P15, and P14 were investigated by site-directed mutagenesis. Full-length transcripts of wild-type BNYVV RNAs 1 and 2 were infectious when coinoculated to protoplasts or leaves of Chenopodium quinoa. RNA 2 transcripts in which P42, P13, and P15 were prematurely terminated by frameshift mutations replicated in protoplasts (when inoculated with wild-type RNA 1) but were not infectious to leaves, indicating that the triple gene block proteins of BNYVV are essential for viral cell-to-cell spread. Mutations in P14 were not lethal in leaf infections but smaller local lesions and lesser amounts of viral RNA were produced. RNA 2-related subgenomic RNA species of 2.6, 1.4, and 0.7 kb were detected; they presumably direct synthesis of P42, P13, and P14. No species of the length predicted for a P15-specific subgenomic RNA was detected.

P42 movement protein of Beet necrotic yellow vein virus is targeted by the movement proteins P13 and P15 to punctate bodies associated with plasmodesmata

Cell-to-cell movement of Beet necrotic yellow vein virus (BNYVV) is driven by a set of three movement proteins--P42, P13, and P15--organized into a triple gene block (TGB) on viral RNA 2. The first TGB protein, P42, has been fused to the green fluorescent protein (GFP) and fusion proteins between P42 and GFP were expressed from a BNYVV RNA 3-based replicon during virus infection. GFP-P42, in which the GFP was fused to the P42 N terminus, could drive viral cell-to-cell movement when the copy of the P42 gene on RNA 2 was disabled but the C-terminal fusion P42-GFP could not. Confocal microscopy of epidermal cells of Chenopodium quinoa near the leading edge of the infection revealed that GFP-P42 localized to punctate bodies apposed to the cell wall whereas free GFP, expressed from the replicon, was distributed uniformly throughout the cytoplasm. The punctate bodies sometimes appeared to traverse the cell wall or to form pairs of disconnected bodies on each side. The punctate bodies co-localized with callose, indicating that they are associated with plasmodesmata-rich regions such as pit fields. Point mutations in P42 that inhibited its ability to drive cell-to-cell movement also inhibited GFP-P42 punctate body formation. GFP-P42 punctate body formation was dependent on expression of P13 and P15 during the infection, indicating that these proteins act together or sequentially to localize P42 to the plasmodesmata.

Identification of genes involved in replication and movement of peanut clump virus

The genome of peanut clump pecluvirus (PCV) consists of two messenger RNA components which contain, respectively, three and five open reading frames (ORFs). Inoculation of transcripts from full-length cDNA clones derived from the PCV RNAs showed that RNA-1 is able to replicate in the absence of RNA-2 in protoplasts, but both RNAs are necessary for plant infection. To investigate the role of different gene products in viral RNA replication and movement, transcripts from mutant cDNA clones were inoculated to protoplasts and to Chenopodium quinoa or Nicotiana benthamiana plants, and progeny RNA was detected by Northern blot analysis. The protein P15, encoded by the third ORF of RNA-1, is essential for efficient replication of the viral genome. The three proteins, P51, P14, and P17, of the triple gene block contained in RNA-2 are involved in localized movement of the viral genome, whereas the coat protein (P23) is also required for vascular movement. Insertion of the beta-glucuronidase reporter gene (GUS) in place of the P23 or P39 genes (the first and the second genes of RNA-2) allows visualization of the virus infection in inoculated leaves. Although the presence of the GUS gene resulted in a lower accumulation of progeny RNA and, despite instability of the construct in planta, histochemical detection of PCV multiplication was more sensitive than Northern blot detection.

The benyvirus RNA silencing suppressor is essential for long-distance movement, requires both zinc-finger and NoLS basic residues but not a nucleolar localization for its silencing-suppression activity

The RNA silencing-suppression properties of Beet necrotic yellow vein virus (BNYVV) and Beet soil-borne mosaic virus (BSBMV) cysteine-rich p14 proteins have been investigated. Suppression of RNA silencing activities were made evident using viral infection of silenced Nicotiana benthamiana 16C, N. benthamiana agroinfiltrated with green fluorescent protein (GFP), and GF-FG hairpin triggers supplemented with viral suppressor of RNA silencing (VSR) constructs or using complementation of a silencing-suppressor-defective BNYVV virus in Chenopodium quinoa. Northern blot analyses of small-interfering RNAs (siRNAs) in agroinfiltration tests revealed reduced amounts of siRNA, especially secondary siRNA, suggesting that benyvirus VSR act downstream of the siRNA production. Using confocal laser-scanning microscopy imaging of infected protoplasts expressing functional p14 protein fused to an enhanced GFP reporter, we showed that benyvirus p14 accumulated in the nucleolus and the cytoplasm independently of other viral factors. Site-directed mutagenesis showed the importance of the nucleolar localization signal embedded in a C4 zinc-finger domain in the VSR function and intrinsic stability of the p14 protein. Conversely, RNA silencing suppression appeared independent of the nucleolar localization of the protein, and a correlation between BNYVV VSR expression and long-distance movement was established.

P0 proteins of European beet-infecting poleroviruses display variable RNA silencing suppression activity

Post-transcriptional gene silencing (PTGS), or RNA silencing, is one of the key mechanisms of antiviral defence used by plants. To counter this defence response, viruses produce suppressor proteins that are able to inhibit the PTGS pathway or to interfere with some of its function. The aim of this study was to evaluate the RNA silencing suppressor (RSS) activity of P0 proteins from selected European isolates of the beet-infecting poleroviruses beet chlorosis virus (BChV) and beet mild yellowing virus (BMYV) using two different experimental systems: (i) agro-infiltration of Nicotiana benthamiana green fluorescent protein-positive plants and (ii) mechanical inoculation of Chenopodium quinoa using a beet necrotic yellow vein virus (BNYVV, genus Benyvirus) RNA3-based replicon. The results demonstrated that P0 of most BMYV isolates exhibited RSS activity, although at various efficiencies among isolates. Conversely, P0 of BChV isolates displayed no RSS activity in either of the two systems under the experimental conditions used. These results are the first reported evidence that P0 proteins of two closely related beet poleroviruses show strain-specific differences in their effects on RNA silencing.

Cell-to-cell movement of beet necrotic yellow vein virus: I. Heterologous complementation experiments provide evidence for specific interactions among the triple gene block proteins

Cell-to-cell movement of beet necrotic yellow vein virus (BNYVV) requires three proteins encoded by a triple gene block (TGB) on viral RNA 2. A BNYVV RNA 3-derived replicon was used to express movement proteins to functionally substitute for the BNYVV TGB proteins was tested by coinoculation of TGB-defective BNYVV with the various replicons to Chenopodium quinoa. Trans-heterocomplementation was successful with the movement protein (P30) of tobacco mosaic virus but not with the tubule-forming movement proteins of alfalfa mosaic virus and grapevine fanleaf virus. Trans-complementation of BNYVV movement was also observed when all three TGB proteins of the distantly related peanut clump virus were supplied together but not when they were substituted for their BNYVV counterparts one by one. When P30 was used to drive BNYVV movement in trans, accumulation of the first TGB protein of BNYVV was adversely affected by null mutations in the second and third TGB proteins. Taken together, these results suggest that highly specific interactions among cognate TGB proteins are important for their function and/or stability in planta.

The small cysteine-rich protein P14 of beet necrotic yellow vein virus regulates accumulation of RNA 2 in cis and coat protein in trans

The effect of null mutations of the small cysteine-rich protein P14 encoded by RNA 2 of beet necrotic yellow vein virus has been investigated using in vitro transcripts of viral RNA to infect Chenopodium quinoa protoplasts. The P14 mutations down-regulated RNA 2 accumulation by approximately 10- to 50-fold. Accumulation of minus-strand RNA 2 was also diminished but RNA 1 accumulation was much less affected. The inhibition of RNA 2 accumulation could not be complemented in trans by providing P14 from another source (either a second molecule of RNA 2 or an RNA 3-based replicon) containing and expressing the P14 gene. The P14 null mutations dramatically inhibited accumulation of viral coat protein, which is encoded by the 5'-proximal gene on RNA 2, but this effect could be complemented in trans, indicating that it occurs by a mechanism distinct from that affecting RNA 2 accumulation. Transient expression experiments were also carried out in which a plasmid expressing P14 and plasmids expressing a reporter gene placed downstream of potential translational control sequences (the 5'-noncoding sequences of RNAs 2, 3, or 4) were introduced into C. quinoa or Nicotiana tabacum leaves by microprojectile bombardment. Coexpression of P14 produced a 3- to 4-fold stimulation of reporter gene expression levels for all the constructs. The lack of sequence specificity suggests that this phenomenon is not directly related to the RNA 2-specific stimulation of coat protein accumulation observed in a viral infection.

Beet necrotic yellow vein virus subgenomic RNA3 is a cleavage product leading to stable non-coding RNA required for long-distance movement

Beet necrotic yellow vein virus (BNYVV) is a multipartite RNA virus. BNYVV RNA3 does not accumulate in non-host transgenic Arabidopsis thaliana plants when expressed using a 35S promoter. However, a 3'-derivative species has been detected in transgenic plants and in transient expression assays conducted in Nicotiana benthamiana and Beta macrocarpa. The 3'-derivative species is similar to the previously reported subgenomic RNA3 produced during virus infection. 5' RACE revealed that the truncated forms had identical 5' ends. The 5' termini carried the coremin motif also present on BNYVV RNA5, beet soil-borne mosaic virus RNA3 and 4, and cucumber mosaic virus group 2 RNAs. This RNA3 species lacks a m(7)Gppp at the 5' end of the cleavage products, whether expressed transiently or virally. Mutagenesis revealed the importance of the coremin sequence for both long-distance movement and stabilization of the cleavage product in vivo and in vitro. The isolation of various RNA3 5'-end products suggests the existence of a cleavage between nt 212 and 1234 and subsequent exonucleolytic degradation, leading to the accumulation of a non-coding RNA. When RNA3 was incubated in wheatgerm extracts, truncated forms appeared rapidly and their appearance was protein- and divalent ion-dependent.

Shortened forms of beet necrotic yellow vein virus RNA-3 and -4: internal deletions and a subgenomic RNA

Beet necrotic yellow vein virus RNA-3 and RNA-4, produced as full-length biologically active transcripts in vitro, can undergo spontaneous internal deletions when inoculated onto Chenopodium quinoa leaves along with RNA-1 and -2. The deletion process is specific, giving rise to only a few major species, and can be rapid; deleted forms appear after only one or two passages in leaves. In one of the shortened forms of RNA-4, the deletion precisely eliminated one copy of a 15 nucleotide (nt) direct sequence repeat from the full-length prototype sequence, suggesting that 'copy-choice' switching of the replicase-template complex from one repeat to the other during RNA replication was responsible for the generation of this deletion. The deletion found in a major shortened form of RNA-3, on the other hand, did not occur near sequence repeats but began with GU and ended with AG like a nuclear intron sequence. Thus it is possible that the deleted sequence has been removed by splicing. However, two other deletions that were characterized were not associated with either of these types of sequence feature. An approximately 600 nt 5'-terminally truncated non-encapsidated form of RNA-3 was also detected in infected plant tissue. The evidence suggests that it is a subgenomic RNA derived from RNA-3.

The first triple gene block protein of peanut clump virus localizes to the plasmodesmata during virus infection

The subcellular localization of the first triple gene block protein (TGBp1) of peanut clump pecluvirus (PCV) was studied by subcellular fractionation and immunogold cytochemistry using TGBp1-specific antibodies raised against a fusion protein expressed in and purified from bacteria. In the inoculated and apical leaves of virus-infected Nicotiana benthamiana, TGBp1 localized to the cell wall and P30 fractions. Electron microscopy of immunogold-decorated ultrathin sections of the infected leaf tissue revealed TGBp1-specific labeling of the plasmodesmata joining mesophyll cells. In longitudinal sections of the plasmodesmata, the TGBp1-specific labeling was most commonly associated with the plasmodesmal collar region. In transgenic N. benthamiana, which constitutively expressed TGBp1, no TGBp1-specific immunogold labeling of plasmodesmata was observed, but plasmodesmata were gold decorated when the transgenic plants were infected with a TGBp1-defective PCV mutant, indicating that factors induced by the virus infection target and/or anchor the transgene TGBp1 to the plasmodesmata.

Subcellular localization of the Triple Gene Block movement proteins of Beet necrotic yellow vein virus by electron microscopy

The Triple Gene Block proteins TGBp1, TGBp2, and TGBp3 of Beet necrotic yellow vein virus (BNYVV) are required for efficient cell-to-cell spread of the infection. The TGB proteins can drive cell-to-cell movement of BNYVV in trans when expressed from a co-inoculated BNYVV RNA 3-based 'replicon'. TGBp2 and TGBp3 expressed from the replicon were nonfunctional in this assay if they were fused to the green fluorescent protein (GFP), but addition of a hemagglutinin (HA) tag to their C-termini did not incapacitate movement. Immunogold labeling of ultrathin sections treated with HA-specific antibodies localized TGBp2-HA and TGBp3-HA to what are probably structurally modified plasmodesmata (Pd) in infected cells. A similar subcellular localization was observed for TGBp1. Large gold-decorated membrane-rich bodies containing what appear to be short fragments of endoplasmic reticulum were observed near the cell periphery. The modified gold-decorated Pd and the membrane-rich bodies were not observed when the TGB proteins were produced individually in infections using the Tobacco mosaic virus P30 protein to drive cell-to-cell movement, indicating that these modifications are specific for TGB-mediated movement.

Multiplication of beet necrotic yellow vein virus RNA 3 lacking a 3' poly(A) tail is accompanied by reappearance of the poly(A) tail and a novel short U-rich tract preceding it

Beet necrotic yellow vein virus RNAs 1 and 2 but not RNAs 3 and 4 are required for viral multiplication in Chenopodium quinoa leaves. Elimination of the 3' poly(A) tail from RNA 3 transcripts markedly attenuated their ability to be amplified when co-inoculated with RNAs 1 and 2 to this host. Successful multiplication of the tailless RNA 3 was accompanied by the reappearance of new 3' poly(A) tails on the progeny. The evidence suggests that the newly acquired poly(A) sequence results from the action of a poly(A) polymerase rather than recombination with the homologous 3' terminal domains of RNAs 1 or 2. An unexpected feature of these progeny RNA 3 molecules was the presence of a novel short heterogenous U-rich tract separating the poly(A) tail from the 3' end of the heteropolymeric RNA 3 sequence proper.

Rapid screening of RNA silencing suppressors by using a recombinant virus derived from beet necrotic yellow vein virus

To counteract plant defence mechanisms, plant viruses have evolved to encode RNA silencing suppressor (RSS) proteins. These proteins can be identified by a range of silencing suppressor assays. Here, we describe a simple method using beet necrotic yellow vein virus (BNYVV) that allows a rapid screening of RSS activity. The viral inoculum consisted of BNYVV RNA1, which encodes proteins involved in viral replication, and two BNYVV-derived replicons: rep3-P30, which expresses the movement protein P30 of tobacco mosaic virus, and rep5-X, which allows the expression of a putative RSS (X). This approach has been validated through the use of several known RSSs. Two potential candidates have been tested and we show that, in our system, the P13 protein of burdock mottle virus displays RSS activity while the P0 protein of cereal yellow dwarf virus-RPV does not.

Beet Necrotic Yellow Vein Virus Noncoding RNA Production Depends on a 5'→3' Xrn Exoribonuclease Activity

The RNA3 species of the beet necrotic yellow vein virus (BNYVV), a multipartite positive-stranded RNA phytovirus, contains the 'core' nucleotide sequence required for its systemic movement in Beta macrocarpa. Within this 'core' sequence resides a conserved "coremin" motif of 20 nucleotides that is absolutely essential for long-distance movement. RNA3 undergoes processing steps to yield a noncoding RNA3 (ncRNA3) possessing "coremin" at its 5' end, a mandatory element for ncRNA3 accumulation. Expression of wild-type (wt) or mutated RNA3 in Saccharomyces cerevisiae allows for the accumulation of ncRNA3 species. Screening of S.cerevisiae ribonuclease mutants identified the 5'-to-3' exoribonuclease Xrn1 as a key enzyme in RNA3 processing that was recapitulated both in vitro and in insect cell extracts. Xrn1 stalled on ncRNA3-containing RNA substrates in these decay assays in a similar fashion as the flavivirus Xrn1-resistant structure (sfRNA). Substitution of the BNYVV-RNA3 'core' sequence by the sfRNA sequence led to the accumulation of an ncRNA species in yeast in vitro but not in planta and no viral long distance occurred. Interestingly, XRN4 knockdown reduced BNYVV RNA accumulation suggesting a dual role for the ribonuclease in the viral cycle.

A Viral Noncoding RNA Complements a Weakened Viral RNA Silencing Suppressor and Promotes Efficient Systemic Host Infection

Systemic movement of beet necrotic yellow vein virus (BNYVV) in Beta macrocarpa depends on viral RNA3, whereas in Nicotiana benthamiana this RNA is dispensable. RNA3 contains a coremin motif of 20 nucleotides essential for the stabilization of noncoding RNA3 (ncRNA3) and for long-distance movement in Beta species. Coremin mutants that are unable to accumulate ncRNA3 also do not achieve systemic movement in Beta species. A mutant virus carrying a mutation in the p14 viral suppressor of RNA silencing (VSR), unable to move long distances, can be complemented with the ncRNA3 in the lesion phenotype, viral RNA accumulation, and systemic spread. Analyses of the BNYVV VSR mechanism of action led to the identification of the RNA-dependent RNA polymerase 6 (RDR6) pathway as a target of the virus VSR and the assignment of a VSR function to the ncRNA3.

Chimeric vector construction for higher-plant transformation

A chimeric vector pKR612B1 was developed containing the neomycin phosphotransferase (APH) gene from the Tn5 transposon under the control of the gene VI promoter of cauliflower mosaic virus (CaMV), and was used to transform higher plant protoplasts. Plasmid pDOB612, the parental vector of pKR612B1, has two unique restriction sites, SmaI and BamHI, positioned just downstream of the CaMV gene VI promoter sequence. These unique cloning sites can be used for any kind of gene insertion into this vector. Using the polyethylene glycol transformation procedure, a large number of turnip and tobacco protoplasts were transformed and proved to be resistant to kanamycin (Km). From tobacco protoplasts whole Km-resistant plants were regenerated and shown to contain the integrated foreign gene. APH activity was detected in both transformed calli and in regenerated plants. DNA from transformed clones was analysed by Southern blot hybridization, showing the presence of the Tn5-derived gene.

Ins and Outs of Multipartite Positive-Strand RNA Plant Viruses: Packaging versus Systemic Spread

Viruses possessing a non-segmented genome require a specific recognition of their nucleic acid to ensure its protection in a capsid. A similar feature exists for viruses having a segmented genome, usually consisting of viral genomic segments joined together into one viral entity. While this appears as a rule for animal viruses, the majority of segmented plant viruses package their genomic segments individually. To ensure a productive infection, all viral particles and thereby all segments have to be present in the same cell. Progression of the virus within the plant requires as well a concerted genome preservation to avoid loss of function. In this review, we will discuss the "life aspects" of chosen phytoviruses and argue for the existence of RNA-RNA interactions that drive the preservation of viral genome integrity while the virus progresses in the plant.

Molecular basis for mitochondrial localization of viral particles during beet necrotic yellow vein virus infection

During infection, Beet necrotic yellow vein virus (BNYVV) particles localize transiently to the cytosolic surfaces of mitochondria. To understand the molecular basis and significance of this localization, we analyzed the targeting and membrane insertion properties of the viral proteins. ORF1 of BNYVV RNA-2 encodes the 21-kDa major coat protein, while ORF2 codes for a 75-kDa minor coat protein (P75) by readthrough of the ORF1 stop codon. Bioinformatic analysis highlighted a putative mitochondrial targeting sequence (MTS) as well as a major (TM1) and two minor (TM3 and TM4) transmembrane regions in the N-terminal part of the P75 readthrough domain. Deletion and gain-of-function analyses based on the localization of green fluorescent protein (GFP) fusions showed that the MTS was able to direct a reporter protein to mitochondria but that the protein was not persistently anchored to the organelles. GFP fused either to MTS and TM1 or to MTS and TM3-TM4 efficiently and specifically associated with mitochondria in vivo. The actual role of the individual domains in the interaction with the mitochondria seemed to be determined by the folding of P75. Anchoring assays to the outer membranes of isolated mitochondria, together with in vivo data, suggest that the TM3-TM4 domain is the membrane anchor in the context of full-length P75. All of the domains involved in mitochondrial targeting and anchoring were also indispensable for encapsidation, suggesting that the assembly of BNYVV particles occurs on mitochondria. Further data show that virions are subsequently released from mitochondria and accumulate in the cytosol.

Beet necrotic yellow vein virus coat protein-mediated protection in sugarbeet (Beta vulgaris L.) protoplasts

Transformed Beta vulgaris L. suspension cultures were obtained after cocultivation of sugarbeet cells with Agrobacterium tumefaciens harbouring a binary vector containing the coat protein gene of beet necrotic yellow vein virus inserted between the kanamycin resistance gene and a ß-glucuronidase reporter gene. Protoplasts were isolated both from untransformed cells, and from transformed cells expressing the viral coat protein, and both were then infected with beet necrotic yellow vein virus. Comparison of the levels of infectivity shows that the expression of the coat protein gene in sugarbeet protoplasts mediates high levels of protection against infection by beet necrotic yellow vein virus.

Beet necrotic yellow vein virus particles localize to mitochondria during infection

Fluorescent beet necrotic yellow vein virus (BNYVV) particles were produced by replacing part of the readthrough domain of the minor coat protein P75 with the green fluorescent protein (GFP). The recombinant virus was functional in plants and P75-GFP was incorporated at one end of the rod-shaped virions. Laser scanning confocal microscopy and transmission electron microscopy showed that virus-like particles, almost certainly authentic BNYVV virions, localized to the cytoplasmic surface of mitochondria at early times postinfection but relocated at later times to semiordered clusters in the cytoplasm. This is the first report of specific targeting of plant virus particles to the mitochondria in vivo.

Artificial defective interfering RNAs derived from RNA 2 of beet necrotic yellow vein virus

Long internal deletions were introduced into cloned cDNA of beet necrotic yellow vein virus RNAs 1-4 and transcripts containing the deletions were tested for their ability to inhibit replication of viral RNA in Chenopodium quinoa protoplasts and plants. No inhibition was observed with the deletion mutants based on RNAs 1, 3 and 4 but the RNA 2 deletion mutants all provoked a dramatic inhibition of synthesis of viral RNAs 1 and 2.

Visualisation of transgene expression at the single protoplast level

Protoplasts are currently used to study the expression of genes following transformation. Expression is followed on a population of protoplasts after total protein extraction by conventional western blotting or measure of the enzymatic activity of the transgenic protein. We describe here a new method, called protoplast printing, allowing easy detection of the fraction of cells expressing a certain protein within a population of protoplasts. It consists of immobilization of the protoplast proteins on a nitrocellulose filter, so as to retain the outlines of the cell, followed by immunological detection of the protein of interest. The only special requirement is an antibody specific for the protein. We have studied the expression of the BNYVV coat protein after electroporation of Chenopodium quinoa protoplasts with viral RNAs, and the expression of the NPT II gene in protoplasts isolated from transgenic tobacco plants as well as after direct transfer of plasmid DNA into tobacco protoplasts. In both cases - infection with viral RNAs and transformation with plasmid DNA - expressing and non-expressing cells can be distinguished as early as 12h after transfer of the transgenes.

[Lung cancer reveal by mandibular metastasis: a case at the Centre of Consultation and Dental Treatment Dental of Casablanca (CCDTC)]

Metastatic tumors result from hematogenous spread through a tumor located at a distance. All these tumors represent about 1% of malignant tumors of the oral cavity (1). The most common location is the mandible (70%), more rarely maxillary (2). The most frequently encountered tumors are carcinomas or adenocarcinomas of mammary origin, brocho-lung, prostate, kidney or another. This study reports the case of a 46 year-old man, who presented for consultation with a low left laterofacial swelling, paresthesia lip and chin straight associated with pain at the lower edge of the mandible evolving for 2 months. The patient is known to take alcohol and tobacco for 20 years. The panoramic radiograph showed radiolucent image with blurred boundaries at the lower right premolar region. Dentascan revealed an irregular osteolytic lesion with rupture of the table lingual. After surgical exploration, the pathological examination is for a well-differentiated and invasive adenocarcinoma of the mandible. Extension work-up shows the presence of a tumor right lung, a lytic lesion at the 8th costal arch, the fourth dorsal vertebra and another location in fibula. The surgical exploration of pulmonary was performed and confirmed the pulmonary primitive localization of adenocarcinoma.