Role of vascular endothelial growth factor in protection of intrahepatic cholangiocytes mediated by hypoxic preconditioning after liver transplantation in rats

OBJECTIVE

To investigate the effect on intrahepatic cholangiocytes mediated by hypoxic preconditioning (HP) after liver transplantation and the role of vascular endothelial growth factor (VEGF).

MATERIALS AND METHODS

This experiment was based on a model of rat orthotopic liver autotransplantation. Sprague-Dawley rats were randomly divided into 3 groups: normal control, autotransplantation (AT), and HP. The HP group was subjected to 8% oxygen atmosphere for 90 minutes before surgery. At 6, 12, 24, and 48 hours after autotransplantation, the rats were killed for testing .Serum total bilirubin, direct bilirubin, and alkaline phosphatase concentrations were determined. The microstructure of cholangiocytes and the ultramicrostructure of cholangioles were determined. Immunohistochemistry was used to detect the expression of VEGF and the proliferation rate of cholangiocytes.

RESULTS

Total bilirubin, direct bilirubin, and alkaline phosphatase concentrations in the AT group increased considerably more than in the HP group during the entire interval (P < .05). Light microscopy demonstrated that the microstructure of cholangiocytes in the AT group was damaged more seriously than in the HP group. At transmission electron microscopy, the ultramicrostructure of cholangioles was changed more obviously than in the HP group. The expression of VEGF on cholangiocytes and the proliferation rate of cholangiocytes were higher in the HP group than in the AT group over the entire experiment (P < .05).

CONCLUSION

Hypoxic preconditioning has a protective effect on cholangiocytes after liver autotransplantation. The mechanism may be related to HP-induced overexpression of VEGF on cholangiocytes.

Metastasis from endometrial carcinoma to bilateral breasts presenting as inflammatory breast lesions

BACKGROUND

Endometrial carcinoma rarely metastasizes to the bilateral breasts and presents as an inflammatory breast lesion. In this paper, we report a case of bilateral breast metastatic endometrial carcinoma and describe the clinical and pathological features. It is the second case of this kind of disease and the first case report with full clinical data.

CASE REPORT

A 56-year-old Chinese woman (G3, P3) with endometrial carcinoma received cytoreductive surgery and chemotherapy. Approximately 22 months later, she presented with pain in the right axillary region and edema of the right breast. The pathology report confirmed multifocal invasive papillary adenocarcinoma of the right mammary gland, consistent with endometrial carcinoma metastasis. Although she received many lines of chemotherapy, the disease still progressed and metastasized to the contralateral breast. Gefitinib (Iressa) improved symptoms temporarily.

CONCLUSIONS

Bilateral breasts metastasis of endometrial carcinoma is rare and difficult to treat. Molecular targeted therapy may be an effective treatment for breast metastasis.

Analysis of the instability of OTSG of movable nuclear power devices by using the multivariable frequency domain method

A new method for analyzing the problem of the thermal-hydrodynamic instability of OTSG (Once-Through Steam Generator) of movable nuclear power devices is presented in this paper. The method is based on multivariable frequency domain theory and is more efficient for analyzing the instability of OTSG with coupling interactions and complicated boundary conditions than the usually used single variable method. A mathematical model for the system is derived from the fundamental equations by using perturbation, Laplace-transform and the nodalization techniques. The stable boundary and parametric effects on the stability of the system are evaluated with a computer code. Numerical examples are given and the predictions of the model are in good agreement with the experimental results.

First Report of Tobacco rattle virus in Spinach in California

In 2009 in coastal California (Santa Barbara County), commercially grown spinach (Spinacia oleracea) in two nearby fields exhibited symptoms of a previously unrecognized virus-like disease. Symptoms consisted of general chlorosis and bright yellow blotches and spots. Necrotic spots were also associated with the disease. In affected fields, disease occurred in limited, irregularly shaped patches that ranged from one to several meters in diameter. Symptomatic plants were unmarketable and these small patches of spinach were not harvested. With a transmission electron microscope, rigid, rod-shaped particles with a clear central canal were observed from plant sap of the symptomatic spinach. Analysis by a double-antibody sandwich-ELISA assay (Agdia Inc., Elkhart, IN) for Tobacco rattle virus (TRV) showed that the symptomatic plants were positive. Symptomatic spinach from the field was used for mechanical transmission to Chenopodium quinoa, C. murale, C. capitatum, spinach, and sugar beet (Beta vulgaris). All inoculated plants showed chlorotic local lesions and sugar beet showed chlorotic local lesions with rings. To further confirm the presence of TRV, reverse transcription (RT)-PCR was conducted. Total RNA was extracted from the mechanically inoculated symptomatic spinach plants using an RNeasy Plant Kit (Qiagen Inc., Valencia, CA) and used as a template in RT-PCR with forward (5'-TACATCACATCTGCCTGC-3') and reverse (5'-CTTCATTCACACAACCCTTG-3') primers specific to the movement protein gene from the spinach isolate of TRV (GenBank Accession No. AJ007294). Amplicons of the expected size (approximately 562 bp) were obtained. The RT-PCR products were sequenced (GenBank Accession No. GU002156) and compared with TRV sequences in GenBank to confirm the identity of the products. Sequences obtained had 96% nucleotide identity and 97% amino acid identity with TRV sequences available under the GenBank Accession Nos. FJ357571 and AJ007294. On the basis of the data from electron microscopy and serological and molecular analyses, the virus was identified as TRV. Soil samples collected from one of the fields were assayed for nematodes; however, Paratrichodorus or Trichodorus species were not recovered. To our knowledge, this is the first report of TRV in spinach in California. TRV has also been reported in spinach in England (1) and Germany (2). References: (1) A. Kurppa et al. Ann. Appl. Biol. 98:243, 1981. (2) K. Schmidt and R. Koenig. Arch. Virol. 144:503, 1999.

Influence of homeobox B2 antisense oligodeoxynucleotides on the biological characteristics of in vitro cultured primary human umbilical vein endothelial cells

This study aims to explore the influence of homeobox B2 (HOXB2) antisense oligodeoxynucleotides (asodn) on the biological characteristics of in vitro cultured primary human umbilical vein endothelial cells (HUVECs). The distribution of HOXB2 asodn in the HUVECs was observed by fluorescent labelling, and the influence of different concentrations of HOXB2 asodn on the DNA synthesis of HUVECs was assessed. Flow cytometry and a reverse transcriptase-polymerase chain reaction (RT- PCR) method were employed to observe the influence of HOXB2 asodn on HOXB2 expression and the HUVEC cell cycle. After the induction of liposome, the nuclear fluorescent staining of HOXB2 asodn was weaker 15 min after transfection and the staining reached the strongest level at 4-8 h but then weakened and disappeared by 16 h after transfection. This indicated that endothelial DNA synthesis could be inhibited by HOXB2 asodn in a dose-dependent manner. Furthermore, the HUVECs could be delayed in their passage from G1 to S. Simultaneously, expression of HOXB2 mRNA had decreased significantly by 24-48 h after transfection. Clearly, HOXB2 plays important roles in the proliferation of endothelial cells and also affects the cell cycle.

First Report of Apium virus Y on Cilantro, Celery, and Parsley in California

Recently, Apium virus Y (ApVY) was detected in field-grown cilantro (Coriandrum sativum), celery (Apium graveolens), and parsley (Petroselinum crispum) in California. In 2003, cilantro plants growing in three different fields in California (Monterey, San Joaquin, and San Luis Obispo counties) expressed symptoms of mosaic, vein clearing, and stunting. When plant sap was examined by transmission electron microscopy, flexuous, rod-shaped virus particles were observed. Total RNA was extracted from the symptomatic cilantro plants and used as a template in reverse transcription (RT)-PCR using universal potyvirus primers according to Chen et al. (1). The RT-PCR product was cloned into pGEM-T (Promega, Madison, WI) and the insert of 1,713 bp was sequenced (GenBank Accession No. EU515125). Nucleotide sequences from clones derived from three different infected cilantro plants were 89 to 97% identical to ApVY sequences encoding partial sequence of polyprotein in GenBank (Accession Nos. AY049716, EU127499, AF207594, AF203529, and EU255632). In 2007, celery plants showing necrotic line patterns and necrotic lesions on lower leaves and petioles were observed in several fields in two coastal counties in California (Monterey and Santa Clara counties). Flexuous, rod-shaped virus particles were also observed in the sap of those plants. ELISA for Cucumber mosaic virus and RT-PCR for Celery mosaic virus were negative. ApVY specific primers were designed on the basis of a consensus sequence of ApVY identified from cilantro in 2003; reverse primer 5'-GGCTCTTGCTATAGACAAATAGT-3' and forward primer 5'-GAAGACCAAGCCAATGTGTGTA-3'. The sequence of RT-PCR products (GenBank Accession No. EU515126) amplified from infected celery had 90 to 98% nucleotide identity to ApVY. When the deduced amino acid sequences of NIb and CP regions from both cilantro and celery were used for comparison, they showed 95 to 99% identity with the known ApVY GenBank sequences mentioned above. More than 10 asymptomatic parsley plants growing in fields adjacent to the infected celery were also tested for ApVY and found to be infected. ApVY was previously identified in three Apiaceae weeds in Australia (2) and in celery in New Zealand (3). To our knowledge, this is the first report of ApVY on cilantro, celery, and parsley in California. References: (1) J. Chen et al. Arch. Virol. 146:757, 2001. (2) J. Moran et al. Arch. Virol. 147:1855, 2002. (3) J. Tang et al. Plant Dis. 91:1682, 2007.

Neointimal coverage of bare-metal and sirolimus-eluting stents evaluated with optical coherence tomography

OBJECTIVE

To analyse the neointimal coverage of sirolimus-eluting stent (SES) and bare-metal stent (BMS) visualised in vivo by optical coherence tomography (OCT).

METHODS

OCT images were obtained in 26 coronary vessels of 24 patients at 5-93 months after SES or BMS deployment. The short-term BMS group (BMS1) consisted of eight BMS in seven patients at 5-10 months of follow-up, the long-term BMS group (BMS2) consisted of six BMS in six patients at 23-93 months of follow-up, and the SES group (SES) consisted of 13 SES in 10 patients at 6-12 months of follow-up. The strut apposition, strut coverage and mean maximal and minimal neointimal thicknesses (NIT) for both BMS groups and SES were compared.

RESULTS

OCT images were acquired successfully. Significant differences between completely apposed and malapposed stent struts (p<0.0001) and between covered and uncovered stent struts (p<0.0001) were found among the three groups. The mean maximal and minimal NIT in the SES group were all significantly less than those of the BMS1 or BMS2 group, the minimal NIT in the BMS1 group was significantly less than that of the BMS2 but the mean maximal NIT was no significant difference between the BMS1 and BMS2 groups. In an open bifurcation artery, 19 struts visualised by OCT had no discernible coverage or were surrounded by either thrombus or a thick tissue layer.

CONCLUSIONS

OCT imaging can clearly visualise stent apposition and neointimal coverage of stent struts. Incomplete strut apposition and lack of strut coverage occurred with a significantly higher frequency in SES than in BMS. These findings may explain the occurrence of late thrombosis in SES. Optical coherence tomography (OCT) is the optical analogue to ultrasound, measuring the back-reflection of infrared light instead of sound waves. The greatest advantage of OCT is its high resolution, which exceeds that of any currently available in vivo imaging technology. The resolution of catheter-based systems is in the range of 10-20 microm. Furthermore, resolutions as high as 4 microm have been achieved ex vivo with more sophisticated techniques that may be applicable to future catheter-based approaches. The main components of various atheromatous plaques can be identified in OCT images, and have been validated in a histology-controlled study. Several studies have demonstrated the feasibility of OCT imaging in patients undergoing percutaneous coronary intervention (PCI). The aim of the present study was to use OCT to analyse the neointimal coverage of sirolimus-eluting stents (SES), compared with that of bare-metal stents (BMS).

Nodal signals pattern vertebrate embryos

Vertebrate embryonic patterning requires several conserved inductive signals-including Nodal, Bmp, Wnt and Fgf signals. Nodal, which is a member of the transforming growth factor beta (TGFbeta) superfamily, activates a signal transduction pathway that is similar to that of other TGFbeta members. Nodal genes, which have been identified in numerous vertebrate species, are expressed in specific cell types and tissues during embryonic development. Nodal signal transduction has been shown to play a pivotal role in inducing and patterning mesoderm and endoderm, and in regulating neurogenesis and left-right axis asymmetry. Antagonists, which act at different steps in the Nodal signal transduction pathway, have been shown to tightly modulate the inductive activity of Nodal.

The Lettuce infectious yellows virus (LIYV)-encoded P26 is associated with plasmalemma deposits within LIYV-infected cells

Cytological, immunological, and mutagenesis approaches were used to identify the viral factors associated with the formation of plasmalemma deposits (PLDs) in whole plants and protoplasts infected by Lettuce infectious yellows virus (LIYV). Transmission electron microscopy and immunogold labeling using polyclonal antibodies to four of the five LIYV RNA 2-encoded large proteins, capsid protein (CP), minor capsid protein (CPm), HSP70 homolog (HSP70h), and P59, showed specific labeling of LIYV virions or virion aggregates around the vesiculated membranous inclusions, but not PLDs in LIYV-infected Nicotiana benthamiana, Nicotiana clevelandii, Lactuca sativa, and Chenopodium murale plants, and Nicotiana tabacum protoplasts. In contrast, antibodies to the RNA 2-encoded P26 showed specific labeling of PLDs but not virions in both LIYV-infected plants and protoplasts. Virion-like particles (VLPs) were seen in protoplasts infected by all LIYV RNA 2 mutants except for the CP (major capsid protein) mutant. PLDs were more difficult to find in protoplasts, but were seen in protoplasts infected by the CP and CPm mutants, but not in protoplasts infected by the P26, HSP70h, or P59 mutants. Interestingly, although the CPm mutant showed VLPs and PLDs, the PLDs did not show associated virions/virion-like particles as was always observed for PLDs seen in protoplasts infected by wild-type LIYV. Immunoblot analyses performed on purified LIYV virions showed that P26 was not detected with purified virions, but was detected in the cell wall, 1000 g and 30,000 g pellet fractions of LIYV-infected plants. These data suggest that P26 is associated with the LIYV-induced PLDs, and in contrast to the other RNA 2-encoded large proteins, P26 is not a virion protein.

Application of disposable plastic microfluidic device arrays with customized chemistries to multiplexed biochemical assays

Plastic microfluidic array platforms and synergistic multiplexed assay chemistries are under development for a variety of applications, including assays of gene expression, proteomics, genotyping, DNA sequencing and fragment analysis, sample preparation and high-throughput pharmaceutical discovery. The low production costs of plastic substrates makes possible economical single-use device arrays, eliminating cleaning and sample-to-sample carryover contamination. Hundreds of microchannels and reservoirs are readily included on a single microtitre-plate-size substrate, enabling the manufacture of highly parallel fluidic array systems to increase throughput and speed.

Green fluorescent protein expression from recombinant lettuce infectious yellows virus-defective RNAs originating from RNA 2

Lettuce infectious yellows virus (LIYV) RNA 2 defective RNAs (D RNAs) were compared in protoplasts for their ability to replicate and to express the green fluorescent protein (GFP) from recombinant D RNA constructs. Initially four LIYV D RNAs of different genetic composition were compared, but only two (LIYV D RNA M5 and M18) replicated to high levels. Both of these contained at least two complete ORFs, one being the 3'-terminal ORF encoding P26. Northern hybridization analysis using probes corresponding to 3' regions of LIYV RNA 2 detected the P26 subgenomic RNA from protoplasts infected with LIYV RNAs 1 and 2 or protoplasts inoculated only with RNA 1 plus either the LIYV D RNA M5 or M18, suggesting that these LIYV D RNAs served as templates to generate the P26 subgenomic RNA. The GFP coding region was inserted as an in-frame insertion into the P26 coding region of the LIYV M5 and M18 D RNAs, yielding M5gfp and M18gfp. When transcripts of M5gfp and M18gfp were used to inoculate protoplasts, bright fluorescence was seen only when they were co-inoculated with LIYV RNA 1. The percentage of fluorescent protoplasts ranged from experiment to experiment, but was as high as 5.8%. Time course analyses showed that fluorescence was not detected before 48 h pi, and this correlated with the timing of LIYV RNA 2 and RNA 2 D RNA accumulation, but not with that of LIYV RNA 1.

Heterogeneity within medullary-type TCRalphabeta(+)CD3(+)CD4(-)CD8(+) thymocytes in normal mouse thymus

The functional maturation process of medullary-type CD4(-)CD8(+) [CD8 single-positive (SP)] thymocytes remains largely uncharacterized. We describe a phenotypic analysis of CD8 SP medullary-type thymocytes and find a remarkable heterogeneity within this thymic cell population. While mature CD8(+) T cells in the periphery are relatively homogeneous (TCRalphabeta(+)CD3(+)Qa-2(+) HSA(-)3G11(-)6C10(-)CD69(-)), CD8 SP medullary-type thymocytes contain discrete subpopulations that can be identified by differential expression of several cell-surface markers. We have identified at least six discrete subpopulations in the subset of TCRalphabeta(+)CD3(+) CD8 SP cells in the thymus. According to the expressed phenotypes, a linear developmental pathway is predicted among these CD8 SP subpopulations as follows: 6C10(+)CD69(+)HSA(hi)3G11(+)Qa-2(-) --> 6C10(-)CD69(+)HSA(hi/int)3G11(+)Qa-2(-) --> 6C10(-)CD69(-)HSA(int)3G11(+)Qa-2(-) --> 6C10(-)CD69(-)HSA(lo)3G11(+)Qa-2(-) --> 6C10(-)CD69(-)HSA(-/lo)3G11(-)Qa-2(-) --> 6C10(-)CD69(-)HSA(-/lo)3G11(-)Qa-2(+). This study provides a framework for understanding CD8 SP T cell maturation in the thymic medulla.

Apoptosis in atrophic skeletal muscle induced by brachial plexus injury in rats

BACKGROUND

Skeletal muscle atrophy induced by denervation is associated with apoptosis. This study was undertaken to determine the role of apoptosis and the expression of apoptosis-associated genes in rat skeletal muscle made atrophic by brachial plexus injury, and to study the apoptotic signal transduction pathway.

METHODS

An animal model of skeletal muscle atrophy was established in rats by severing the brachial plexus of one forelimb. Apoptosis of muscle cells was investigated with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate end labeling, flow cytometry, deoxyribonucleic acid (DNA) electrophoresis, and electron microscopy. The apoptosis-associated genes Fas, FADD, Caspase 8, c-myc, p53, and Bcl-2 were detected by immunohistochemistry and Northern blot.

RESULTS

By terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate end labeling and flow cytometry we found that the percentage of apoptotic muscle cells was higher in atrophic than in healthy skeletal muscle (p < 0.05). DNA laddering could be seen in gel electrophoresis of DNA from atrophic muscle. By electron microscopy, we observed morphologic change of early apoptosis, such as aggregation of chromosomes, expansion of nucleic cistern, and contraction of the nucleus. Using immunohistochemistry, we determined that in atrophic muscle Fas, FADD, and Caspase-8 genes were highly expressed, whereas Bcl-2 was poorly expressed (p < 0.01). However, we did not detect a change in the expression of p53 or c-myc genes. Northern blots indicated that Fas messenger ribonucleic acid was higher and Bcl-2 messenger ribonucleic acid was lower in atrophic than in healthy muscle (p < 0.01).

CONCLUSION

There are many more apoptotic cells in muscle atrophied as a result of brachial plexus injury than in healthy muscle, and apoptosis plays an important role in the pathogenesis of atrophy. The apoptotic signal may be transmitted from Fas to FADD to Caspase-8, with a decrease in Bcl-2 expression aggravating the process.

T-cell killing of heterogenous tumor or viral targets with bispecific chimeric immune receptors

We have previously described several novel chimeric immune receptors (CIRs) that redirect human T cells to kill malignant or HIV-infected cells. These CIRs comprise a cancer- or virus-specific ligand or single-chain antibody fused to the signaling domain of the T-cell receptor CD3-zeta subunit. Binding of the ligand- or antibody-based CIR to the target antigen (Ag) triggers T-cell-mediated cytolysis of the tumor- or virus-infected cell independent of target cell major histocompatibility complex class I expression. A new type of CIR was developed to mediate the lysis of cells that expressed one or more distinct viral or tumor Ags; three bispecific CIRs (BCIRs) were generated that recognized the carcinoembryonic Ag (CEA) and TAG-72 tumor Ags or, alternatively, distinct epitopes in the HIV envelope (HIVenv). T cells expressing the antitumoral Ag BCIR lysed both CEA- and TAG-72-expressing targets and did not kill Ag-negative targets or target cells expressing other members of the CEA family. Similarly, T cells expressing the anti-HIVenv BCIR lysed target cells expressing both the wild-type HIVenv and a mutant HIVenv that lacked the epitopes recognized by the monospecific CIRs. This approach permits the generation of T cells with a broader spectrum of activity capable of killing virus-infected cells and malignant cells and reduces the potential of progression of disease due to Ag loss variants.

Asynchronous accumulation of lettuce infectious yellows virus RNAs 1 and 2 and identification of an RNA 1 trans enhancer of RNA 2 accumulation

Time course and mutational analyses were used to examine the accumulation in protoplasts of progeny RNAs of the bipartite Crinivirus, Lettuce infectious yellow virus (LIYV; family Closteroviridae). Hybridization analyses showed that simultaneous inoculation of LIYV RNAs 1 and 2 resulted in asynchronous accumulation of progeny LIYV RNAs. LIYV RNA 1 progeny genomic and subgenomic RNAs could be detected in protoplasts as early as 12 h postinoculation (p.i.) and accumulated to high levels by 24 h p.i. The LIYV RNA 1 open reading frame 2 (ORF 2) subgenomic RNA was the most abundant of all LIYV RNAs detected. In contrast, RNA 2 progeny were not readily detected until ca. 36 h p.i. Mutational analyses showed that in-frame stop codons introduced into five of seven RNA 2 ORFs did not affect accumulation of progeny LIYV RNA 1 or RNA 2, confirming that RNA 2 does not encode proteins necessary for LIYV RNA replication. Mutational analyses also supported that LIYV RNA 1 encodes proteins necessary for replication of LIYV RNAs 1 and 2. A mutation introduced into the LIYV RNA 1 region encoding the overlapping ORF 1B and ORF 2 was lethal. However, mutations introduced into only LIYV RNA 1 ORF 2 resulted in accumulation of progeny RNA 1 near or equal to wild-type RNA 1. In contrast, the RNA 1 ORF 2 mutants did not efficiently support the trans accumulation of LIYV RNA 2. Three distinct RNA 1 ORF 2 mutants were analyzed and all exhibited a similar phenotype for progeny LIYV RNA accumulation. These data suggest that the LIYV RNA 1 ORF 2 encodes a trans enhancer for RNA 2 accumulation.

[Apoptosis in atrophic skeletal muscle induced by brachial plexus injury in rats]

OBJECTIVE

To study the role of apoptosis and the expression of apoptosis-associated genes in skeletal muscle atrophy induced by brachial plexus injury in rats.

METHODS

Rat models of skeletal muscle atrophy were established by cutting off brachial plexus of one upper limb. Apoptosis of muscular cells was investigated by TUNEL, flowcytometry, DNA electrophoresis and electromicroscopic observation. The apoptosis associated genes such as Fas, FADD, Caspase 8, c-myc, P53 and Bcl-2 were detected by immunohistochemical method (ABC) and Northern-blot.

RESULTS

It was found with TUNEL and flowcytometry that the percentage of apoptotic muscle cell rose obviously in atrophic skeletal muscle (P < 0.05). DNA laddering could be seen in DNA gel electrophoresis of atrophic muscle after brachial injury. Morphologic changes of early stage in apoptotic cell could be seen under eletcromicroscope, such as the aggregation of chromosome, the expansion of nucleic cistern and the contraction of nucleus. Fas, FADD and Caspase genes were expressed highly and Bcl-2 gene was expressed lowly with immunohistochemical method in atrophic muscle. The results were all significantly different with that of the controls (P < 0.01). But the expression changes in P53 and c-myc genes were not obvious. The result of Northern-blot indicated that the mRNA of Fas gene rose and that of Bcl-2 gene decreased obviously (P < 0.01) in atrophic muscle induced by brachial plexus injury.

CONCLUSION

There are much more apoptotic cells in atrophic muscle induced by brachial plexus injury, and apoptosis plays an important role in its pathogenesis. The apoptotic signal maybe transmitted through Fas-->FADD-->Caspase 8, and the decrease in Bcl-2 gene expression aggravates the process.

A heterogeneous population of defective RNAs is associated with lettuce infectious yellows virus

Preparations of dsRNAs and virion RNAs extracted from Nicotiana clevelandii plants infected with the bipartite Lettuce infectious yellows virus (LIYV) were found to contain multiple LIYV RNA species. In addition to the two LIYV genomic RNAs, three types of RNAs were observed: (a) 3' coterminal subgenomic RNAs; (b) RNAs containing LIYV RNA 1 or RNA 2 5' terminus but lacking the 3' terminus; and (c) RNAs with both LIYV RNA 2 3' and 5' termini but each with a central extensive deletion, a structure typical of defective RNAs (D RNAs). No D RNA-like RNAs were detected for LIYV RNA 1. A reverse transcription followed by polymerase chain reaction (RT-PCR) strategy was used to clone from virion RNAs several LIYV RNA 2 D RNAs as cDNAs. Nucleotide sequence analysis of 43 cloned cDNAs showed in some D RNAs the presence of a stretch of 1-5 nt in the junction site that is repeated in the genomic RNA 2 in the two positions flanking the junction site or in close proximity. Some D RNAs contained in the junction site one or several extra nucleotides not present in the LIYV genomic RNA 2. Two of the cloned cDNAs were used to generate in vitro transcripts, and infectivity studies showed that both D RNAs were replication competent in protoplasts when coinoculated with LIYV RNAs 1 and 2 or with only LIYV RNA1. Neither D RNA showed obvious effects upon LIYV RNA 1 and RNA 2 accumulation in coinfected protoplasts. These data suggest that LIYV infections contain a heterogeneous population of LIYV RNA 2 D RNAs, and some are encapsidated into virions.

First Report of Cucurbit Yellow Stunting Disorder Virus (Genus Crinivirus) in North America

In late summer 1999, field- and greenhouse-grown melon plants (Cucumis melo) showing severe stunting and yellowing symptoms were observed near Donna in southern Texas and near the town of Reynosa in northern Mexico. Symptoms were typical of those caused by viruses in the genus Crinivirus, family Closteroviridae. High populations of Bemisia spp. whiteflies were associated with these plantings, with many plants showing heavy infestation. Laboratory analyses showed that melon plants from both locations were infected by the whitefly-transmitted Cucurbit yellow stunting disorder virus (CYSDV). Positive hybridization reactions with digoxigenin-UTP-labeled transcript probes corresponding to the CYSDV heat shock protein 70 (HSP70) homolog coding region (1) were obtained for RNAs extracted from symptomatic plants. Similar probes for the related Lettuce infectious yellows virus (LIYV) and Beet pseudo-yellows virus (BPYV), two whitefly-transmitted viruses previously reported from North America (2), did not hybridize with the RNAs. Definitive confirmation of CYSDV was obtained by performing reverse-transcription polymerase chain reaction (RT-PCR) analyses for two distinct CYSDV coding regions. RT-PCR with primers corresponding to CYSDV, but not LIYV or BPYV HSP70 homolog coding regions, gave specific (≈500 bp) products from corresponding test plants. RNAs from healthy control plants gave no RT-PCR product. Because the HSP70 coding region is highly conserved (2), we also performed RT-PCR with primers designed for the Spanish CYSDV capsid protein gene (GenBank accession AJ243000). Positive RT-PCR products of ≈700 bp were obtained only from the Texas and Mexico melon plants. CYSDV is a widespread and damaging virus of cucurbits in southern Europe and the Middle East (2). This is the first report of this important virus in North America. References: (1) Tian et al. Phytopathology 86:1167, 1996. (2) Rubio et al. Phytopathology 89:707, 1999.

Lettuce infectious yellows virus: in vitro acquisition analysis using partially purified virions and the whitefly Bemisia tabaci

Virions of lettuce infectious yellows virus (LIYV; genus Crinivirus) were purified from LIYV-infected plants and their protein composition was analysed by SDS-PAGE and immunoblotting. Virion preparations contained the major capsid protein (CP), but the minor capsid protein (CPm), p59 and the HSP70 homologue were also identified by immunoblot analysis. Immunogold labelling analysis showed that CP constituted the majority of the LIYV virion capsid, but CPm was also part of the capsid and localized to one end of the virion, similar to the polar morphology seen for viruses in the genus Closterovirus. p59 and the HSP70 homologue were not detected on virions by immunogold labelling, but were always detected in virion preparations by immunoblot analysis. Purified LIYV virions were used for in vitro acquisition analysis with Bemisia tabaci whiteflies and were efficiently transmitted to plants. Infectivity neutralization analyses were done using antisera to the LIYV-encoded CP, CPm, p59 and HSP70 homologue. Only antiserum to the CPm effectively neutralized LIYV transmission by B. tabaci. These data suggest that the LIYV-B. tabaci transmission determinants are associated with purified virions, and that the LIYV virion structural protein CPm is involved in transmission by B. tobaci.