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1.
Acta Paediatr ; 110(3): 818-825, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-32892376

RESUMEN

AIM: The aim of this study was to evaluate neurocognitive outcome at 24 months of corrected age after less invasive surfactant application (LISA) in preterm infants born at 23-26 weeks of gestational age. METHODS: Surviving participants of a LISA trial conducted in 13 German level III neonatal intensive care units were reviewed for assessment of developmental outcome, hearing and vision problems, growth and rehospitalisation days. Maternal depression, breastfeeding rates and socio-economic factors were evaluated as potentially confounding factors. RESULTS: In total, 156/182 infants took part in the study, 78 had received surfactant via LISA and 78 via endotracheal intubation. 22% of LISA infants compared to 42% of intubated infants had a psychomotor development index (PDI) <70 (0.012). A significant difference in mental development index (MDI) was observed in the stratum of more mature infants (25 and 26 weeks of GA). For this group, MDI < 70 was observed in 4% of LISA infants vs 21% of intubated infants (P = 0.008). CONCLUSION: At 24 months of age, the LISA-treated infants scored less often PDI < 70 and had similar results in MDI. Infants born at 25 and 26 weeks treated with LISA had lower rates of severe disability. LISA is safe and may be superior.


Asunto(s)
Recien Nacido Extremadamente Prematuro , Surfactantes Pulmonares , Humanos , Lactante , Recién Nacido , Surfactantes Pulmonares/uso terapéutico , Respiración Artificial , Tensoactivos , Resultado del Tratamiento
2.
Sensors (Basel) ; 20(17)2020 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-32859049

RESUMEN

The Karlsruhe Tritium Neutrino (KATRIN) experiment aims at measuring the effective electron neutrino mass with a sensitivity of 0.2 eV/c2, i.e., improving on previous measurements by an order of magnitude. Neutrino mass data taking with KATRIN commenced in early 2019, and after only a few weeks of data recording, analysis of these data showed the success of KATRIN, improving on the known neutrino mass limit by a factor of about two. This success very much could be ascribed to the fact that most of the system components met, or even surpassed, the required specifications during long-term operation. Here, we report on the performance of the laser Raman (LARA) monitoring system which provides continuous high-precision information on the gas composition injected into the experiment's windowless gaseous tritium source (WGTS), specifically on its isotopic purity of tritium-one of the key parameters required in the derivation of the electron neutrino mass. The concentrations cx for all six hydrogen isotopologues were monitored simultaneously, with a measurement precision for individual components of the order 10-3 or better throughout the complete KATRIN data taking campaigns to date. From these, the tritium purity, εT, is derived with precision of <10-3 and trueness of <3 × 10-3, being within and surpassing the actual requirements for KATRIN, respectively.

3.
JAMA ; 324(6): 560-570, 2020 08 11.
Artículo en Inglés | MEDLINE | ID: mdl-32780138

RESUMEN

Importance: Red blood cell transfusions are commonly administered to infants weighing less than 1000 g at birth. Evidence-based transfusion thresholds have not been established. Previous studies have suggested higher rates of cognitive impairment with restrictive transfusion thresholds. Objective: To compare the effect of liberal vs restrictive red blood cell transfusion strategies on death or disability. Design, Setting, and Participants: Randomized clinical trial conducted in 36 level III/IV neonatal intensive care units in Europe among 1013 infants with birth weights of 400 g to 999 g at less than 72 hours after birth; enrollment took place between July 14, 2011, and November 14, 2014, and follow-up was completed by January 15, 2018. Interventions: Infants were randomly assigned to liberal (n = 492) or restrictive (n = 521) red blood cell transfusion thresholds based on infants' postnatal age and current health state. Main Outcome and Measures: The primary outcome, measured at 24 months of corrected age, was death or disability, defined as any of cognitive deficit, cerebral palsy, or severe visual or hearing impairment. Secondary outcome measures included individual components of the primary outcome, complications of prematurity, and growth. Results: Among 1013 patients randomized (median gestational age at birth, 26.3 [interquartile range {IQR}, 24.9-27.6] weeks; 509 [50.2%] females), 928 (91.6%) completed the trial. Among infants in the liberal vs restrictive transfusion thresholds groups, respectively, incidence of any transfusion was 400/492 (81.3%) vs 315/521 (60.5%); median volume transfused was 40 mL (IQR, 16-73 mL) vs 19 mL (IQR, 0-46 mL); and weekly mean hematocrit was 3 percentage points higher with liberal thresholds. Among infants in the liberal vs restrictive thresholds groups, the primary outcome occurred in 200/450 (44.4%) vs 205/478 (42.9%), respectively, for a difference of 1.6% (95% CI, -4.8% to 7.9%; P = .72). Death by 24 months occurred in 38/460 (8.3%) vs 44/491 (9.0%), for a difference of -0.7% (95% CI, -4.3% to 2.9%; P = .70), cognitive deficit was observed in 154/410 (37.6%) vs 148/430 (34.4%), for a difference of 3.2% (95% CI, -3.3% to 9.6%; P = .47), and cerebral palsy occurred in 18/419 (4.3%) vs 25/443 (5.6%), for a difference of -1.3% (95% CI, -4.2% to 1.5%; P = .37), in the liberal vs the restrictive thresholds groups, respectively. In the liberal vs restrictive thresholds groups, necrotizing enterocolitis requiring surgical intervention occurred in 20/492 (4.1%) vs 28/518 (5.4%); bronchopulmonary dysplasia occurred in 130/458 (28.4%) vs 126/485 (26.0%); and treatment for retinopathy of prematurity was required in 41/472 (8.7%) vs 38/492 (7.7%). Growth at follow-up was also not significantly different between groups. Conclusions and Relevance: Among infants with birth weights of less than 1000 g, a strategy of liberal blood transfusions compared with restrictive transfusions did not reduce the likelihood of death or disability at 24 months of corrected age. Trial Registration: ClinicalTrials.gov Identifier: NCT01393496.


Asunto(s)
Trastornos del Conocimiento/etiología , Transfusión de Eritrocitos/efectos adversos , Recien Nacido con Peso al Nacer Extremadamente Bajo , Displasia Broncopulmonar/etiología , Parálisis Cerebral/etiología , Enterocolitis Necrotizante/etiología , Enterocolitis Necrotizante/cirugía , Transfusión de Eritrocitos/mortalidad , Transfusión de Eritrocitos/estadística & datos numéricos , Femenino , Trastornos de la Audición/etiología , Hematócrito/estadística & datos numéricos , Humanos , Lactante , Recien Nacido con Peso al Nacer Extremadamente Bajo/crecimiento & desarrollo , Recién Nacido , Unidades de Cuidado Intensivo Neonatal/estadística & datos numéricos , Masculino , Evaluación de Resultado en la Atención de Salud , Retinopatía de la Prematuridad/terapia , Sensibilidad y Especificidad , Trastornos de la Visión/etiología
4.
Mol Plant Microbe Interact ; 29(3): 197-209, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26713353

RESUMEN

RNA interference (RNAi) is a widely used approach to generate virus-resistant transgenic crops. However, issues of agricultural importance like the long-term durability of RNAi-mediated resistance under field conditions and the potential side effects provoked in the plant by the stable RNAi expression remain poorly investigated. Here, we performed field trials and molecular characterization studies of two homozygous transgenic tomato lines, with different selection markers, expressing an intron-hairpin RNA cognate to the Tomato yellow leaf curl virus (TYLCV) C1 gene. The tested F6 and F4 progenies of the respective kanamycin- and basta-resistant plants exhibited unchanged field resistance to TYLCV and stably expressed the transgene-derived short interfering RNA (siRNAs) to represent 6 to 8% of the total plant small RNAs. This value outnumbered the average percentage of viral siRNAs in the nontransformed plants exposed to TYLCV-infested whiteflies. As a result of the RNAi transgene expression, a common set of up- and downregulated genes was revealed in the transcriptome profile of the plants selected from either of the two transgenic events. A previously unidentified geminivirus causing no symptoms of viral disease was detected in some of the transgenic plants. The novel virus acquired V1 and V2 genes from TYLCV and C1, C2, C3, and C4 genes from a distantly related geminivirus and, thereby, it could evade the repressive sequence-specific action of transgene-derived siRNAs. Our findings shed light on the mechanisms of siRNA-directed antiviral silencing in transgenic plants and highlight the applicability limitations of this technology as it may alter the transcriptional pattern of nontarget genes.


Asunto(s)
Geminiviridae/fisiología , Enfermedades de las Plantas/virología , Plantas Modificadas Genéticamente , Interferencia de ARN , Solanum lycopersicum/genética , Solanum lycopersicum/fisiología , Regulación de la Expresión Génica de las Plantas , Predisposición Genética a la Enfermedad , Datos de Secuencia Molecular , Enfermedades de las Plantas/genética , ARN Interferente Pequeño , Transcriptoma
5.
EMBO J ; 28(20): 3171-84, 2009 Oct 21.
Artículo en Inglés | MEDLINE | ID: mdl-19745810

RESUMEN

The plant viral re-initiation factor transactivator viroplasmin (TAV) activates translation of polycistronic mRNA by a re-initiation mechanism involving translation initiation factor 3 (eIF3) and the 60S ribosomal subunit (60S). QJ;Here, we report a new plant factor-re-initiation supporting protein (RISP)-that enhances TAV function in re-initiation. RISP interacts physically with TAV in vitro and in vivo. Mutants defective in interaction are less active, or inactive, in transactivation and viral amplification. RISP alone can serve as a scaffold protein, which is able to interact with eIF3 subunits a/c and 60S, apparently through the C-terminus of ribosomal protein L24. RISP pre-bound to eIF3 binds 40S, suggesting that RISP enters the translational machinery at the 43S formation step. RISP, TAV and 60S co-localize in epidermal cells of infected plants, and eIF3-TAV-RISP-L24 complex formation can be shown in vitro. These results suggest that RISP and TAV bridge interactions between eIF3-bound 40S and L24 of 60S after translation termination to ensure 60S recruitment during repetitive initiation events on polycistronic mRNA; RISP can thus be considered as a new component of the cell translation machinery.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Caulimovirus/metabolismo , Factor 3 de Iniciación Eucariótica/metabolismo , Regulación de la Expresión Génica de las Plantas , Biosíntesis de Proteínas/fisiología , Subunidades Ribosómicas Grandes de Eucariotas/metabolismo , Proteínas Virales/metabolismo , Proteínas de Arabidopsis/genética , Caulimovirus/genética , Caulimovirus/fisiología , Modelos Biológicos , Reacción en Cadena de la Polimerasa , Polirribosomas/metabolismo , Unión Proteica/genética , Unión Proteica/fisiología , Biosíntesis de Proteínas/genética , Subunidades Ribosómicas Pequeñas de Eucariotas/metabolismo , Técnicas del Sistema de Dos Híbridos , Proteínas Virales/genética
6.
Nucleic Acids Res ; 39(12): 5003-14, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21378120

RESUMEN

To successfully infect plants, viruses must counteract small RNA-based host defense responses. During infection of Arabidopsis, Cauliflower mosaic pararetrovirus (CaMV) is transcribed into pregenomic 35S and subgenomic 19S RNAs. The 35S RNA is both reverse transcribed and also used as an mRNA with highly structured 600 nt leader. We found that this leader region is transcribed into long sense- and antisense-RNAs and spawns a massive quantity of 21, 22 and 24 nt viral small RNAs (vsRNAs), comparable to the entire complement of host-encoded small-interfering RNAs and microRNAs. Leader-derived vsRNAs were detected bound to the Argonaute 1 (AGO1) effector protein, unlike vsRNAs from other viral regions. Only negligible amounts of leader-derived vsRNAs were bound to AGO4. Genetic evidence showed that all four Dicer-like (DCL) proteins mediate vsRNA biogenesis, whereas the RNA polymerases Pol IV, Pol V, RDR1, RDR2 and RDR6 are not required for this process. Surprisingly, CaMV titers were not increased in dcl1/2/3/4 quadruple mutants that accumulate only residual amounts of vsRNAs. Ectopic expression of CaMV leader vsRNAs from an attenuated geminivirus led to increased accumulation of this chimeric virus. Thus, massive production of leader-derived vsRNAs does not restrict viral replication but may serve as a decoy diverting the silencing machinery from viral promoter and coding regions.


Asunto(s)
Arabidopsis/virología , Caulimovirus/genética , ARN Pequeño no Traducido/biosíntesis , ARN Viral/biosíntesis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas Argonautas , Caulimovirus/fisiología , ADN Viral/biosíntesis , Mutación , Enfermedades de las Plantas/virología , Ribonucleasa III/genética , Replicación Viral
7.
Anaesthesiologie ; 72(10): 703-709, 2023 Oct.
Artículo en Alemán | MEDLINE | ID: mdl-37405472

RESUMEN

BACKGROUND: Airway management in children, especially in patients with a difficult airway, remains a major challenge for anesthesiologists, pediatricians, and emergency medicine physicians. In recent years new tools have been introduced into the clinical practice. OBJECTIVE: The aim was to present the current strategies for securing the airway in neonates in perinatal centers levels II and III in Germany, and to collect data on the rare event of coniotomy. MATERIAL AND METHODS: From 5 April 2021 to 15 June 2021, physicians practicing intensive care in pediatrics and neonatology at perinatal centers levels II and III in Germany were surveyed by means of an anonymized online questionnaire. The questionnaire was designed by the authors and verified by pretesting with the help of five pediatric specialists. Contact was made digitally via the e­mail addresses provided on the websites of the respective centers. The survey was administered through the fee for service provider LimeSurvey©. The collected data were transferred to the IBM© statistical package for the social scientists (SPSS, version 28, IBM© Corporation, Armonk, NY, USA) and statistically analyzed. Pearson's χ2-test was used to perform significance testing (significance level p = < 0.05). Only completed questionnaires were included in the analysis. RESULTS: A total of 219 participants completed the questionnaire. Available airway devices: 94.5% (n = 207) nasopharyngeal tubes, 79.9% (n = 175) video laryngoscope/fiber optic, 73.1% (n = 160) laryngeal masks, 64.8% (n = 142) oropharyngeal tube (Guedel). Of the participants 6 (2.7%) performed coniotomy (⌀ 1.6 children). Out of six cases five (83.3%) were resuscitation situations caused by complex anatomical malformations. Training of coniotomy was not provided in 98.6% (n = 216). A Standard Operating Procedure (SOP) for difficult airway in neonates was possessed by 20.1% (n = 44). CONCLUSION: The comparison with international studies showed that the equipment of German perinatal centers is above average. The trend towards acquisition of a video laryngoscope and its importance in clinical routine could be confirmed by our data; however, the fact that 20% of the respondents did not have access to video laryngoscopy suggests that further acquisitions will have to be made here in the future. Front of neck access (FONA) methods remain a critically questioned component of neonatal difficult airway algorithms due to their rarity and the resulting lack of data. In summary of the recommendations of the British Association of Perinatal Medicine (BAPM) and the collected data on the theoretical and practical education of the FONA methods in Germany, the implementation of the FONA methods by pediatricians and neonatologists cannot be recommended. As most resuscitation situations were caused by complex anatomical malformations, the early detection of such malformations by means of high-resolution ultrasound seems to be of particular importance. With improvement of early detection, neonates with potentially unmanageable airway problems can be left on uteroplacental circulation for a prolonged period in order to perform necessary interventions, such as tracheostomy, bronchoscopy, or extracorporeal membrane oxygenation (ECMO) device known as the ex utero intrapartum treatment (EXIT) procedure.

8.
Biochim Biophys Acta ; 1809(11-12): 588-600, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21683815

RESUMEN

RNA silencing refers to processes that depend on small (s)RNAs to regulate the expression of eukaryotic genomes. In plants, these processes play critical roles in development, in responses to a wide array of stresses, in maintaining genome integrity and in defense against viral and bacterial pathogens. We provide here an updated view on the array of endogenous sRNA pathways, including microRNAs (miRNAs), discovered in the model plant Arabidopsis, which are also the basis for antiviral silencing. We emphasize the current knowledge as well as the recent advances made on understanding the defense and counter-defense strategies evolved in the arms race between plants and DNA viruses on both the nuclear and the cytoplasmic front. This article is part of a Special Issue entitled: MicroRNA's in viral gene regulation.


Asunto(s)
Virus ADN/química , ADN de Plantas/química , Virus de Plantas/genética , Interferencia de ARN , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/virología , Regulación de la Expresión Génica de las Plantas , Virus de Plantas/metabolismo , ARN de Planta/química , ARN Interferente Pequeño/química , Proteínas Virales/genética , Proteínas Virales/metabolismo
9.
Mol Plant Microbe Interact ; 24(8): 973-83, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21751853

RESUMEN

Begomoviruses (family Geminiviridae) are single-stranded DNA viruses transmitted by the whitefly Bemisia tabaci. Many economically important diseases in crops are caused by begomoviruses, particularly in tropical and subtropical environments. These include the betasatellite-associated begomoviruses causing cotton leaf curl disease (CLCuD) that causes significant losses to a mainstay of the economy of Pakistan, cotton. RNA interference (RNAi) or gene silencing is a natural defense response of plants against invading viruses. In counter-defense, viruses encode suppressors of gene silencing that allow them to effectively invade plants. Here, we have analyzed the ability of the begomovirus Cotton leaf curl Multan virus (CLCuMV) and its associated betasatellite, Cotton leaf curl Multan ß-satellite (CLCuMB) which, together, cause CLCuD, and the nonessential alphasatellite (Cotton leaf curl Multan alphasatellite [CLCuMA]) for their ability to suppress gene silencing in Nicotiana benthamiana. The results showed that CLCuMV by itself was unable to efficiently block silencing. However, in the presence of the betasatellite, gene silencing was entirely suppressed. Silencing was not affected in any way when infections included CLCuMA, although the alphasatellite was, for the first time, shown to be a target of RNA silencing, inducing the production in planta of specific small interfering RNAs, the effectors of silencing. Subsequently, using a quantitative real-time polymerase chain reaction assay and Northern blot analysis, the ability of all proteins encoded by CLCuMV and CLCuMB were assessed for their ability to suppress RNAi and the relative strengths of their suppression activity were compared. The analysis showed that the V2, C2, C4, and ßC1 proteins exhibited suppressor activity, with the V2 showing the strongest activity. In addition, V2, C4, and ßC1 were examined for their ability to bind RNA and shown to have distinct specificities. Although each of these proteins has, for other begomoviruses or betasatellites, been previously shown to have suppressor activity, this is the first time all proteins encoded by a geminiviruses (or begomovirus-betasatellite complex) have been examined and also the first for which four separate suppressors have been identified.


Asunto(s)
Begomovirus/metabolismo , Nicotiana/virología , Hojas de la Planta/virología , Interferencia de ARN , Virus Satélites/metabolismo , Agrobacterium tumefaciens , Begomovirus/genética , Regulación Viral de la Expresión Génica/fisiología , Genes Supresores/fisiología , Proteínas Fluorescentes Verdes/genética , Interacciones Huésped-Patógeno , Unión Proteica , ARN Viral/metabolismo , Virus Satélites/genética , Nicotiana/genética , Transgenes/fisiología , Proteínas Virales/genética , Proteínas Virales/metabolismo
10.
Nucleic Acids Res ; 36(18): 5896-909, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18801846

RESUMEN

Several RNA silencing pathways in plants restrict viral infections and are suppressed by distinct viral proteins. Here we show that the endogenous trans-acting (ta)siRNA pathway, which depends on Dicer-like (DCL) 4 and RNA-dependent RNA polymerase (RDR) 6, is suppressed by infection of Arabidopsis with Cauliflower mosaic virus (CaMV). This effect was associated with overaccumulation of unprocessed, RDR6-dependent precursors of tasiRNAs and is due solely to expression of the CaMV transactivator/viroplasmin (TAV) protein. TAV expression also impaired secondary, but not primary, siRNA production from a silenced transgene and increased accumulation of mRNAs normally silenced by the four known tasiRNA families and RDR6-dependent secondary siRNAs. Moreover, TAV expression upregulated DCL4, DRB4 and AGO7 that mediate tasiRNA biogenesis. Our findings suggest that TAV is a general inhibitor of silencing amplification that impairs DCL4-mediated processing of RDR6-dependent double-stranded RNA to siRNAs. The resulting deficiency in tasiRNAs and other RDR6-/DCL4-dependent siRNAs appears to trigger a feedback mechanism that compensates for the inhibitory effects.


Asunto(s)
Proteínas de Arabidopsis/antagonistas & inhibidores , Arabidopsis/genética , Arabidopsis/virología , Interferencia de ARN , ARN Interferente Pequeño/biosíntesis , ARN Polimerasa Dependiente del ARN/antagonistas & inhibidores , Transactivadores/metabolismo , Proteínas Virales/metabolismo , Arabidopsis/metabolismo , Caulimovirus/metabolismo , Precursores del ARN/biosíntesis , ARN Bicatenario/biosíntesis , ARN Interferente Pequeño/química , Ribonucleasa III , Ribonucleasas/metabolismo , Transgenes
11.
Arch Dis Child Fetal Neonatal Ed ; 105(2): 190-195, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31248963

RESUMEN

OBJECTIVE: To determine if survival rates of preterm infants receiving active perinatal care improve over time. DESIGN: The German Neonatal Network is a cohort study of preterm infants with birth weight <1500 g. All eligible infants receiving active perinatal care are registered. We analysed data of patients discharged between 2011 and 2016. SETTING: 43 German level III neonatal intensive care units (NICUs). PATIENTS: 8222 preterm infants with a gestational age between 22/0 and 28/6 weeks who received active perinatal care. INTERVENTIONS: Participating NICUs were grouped according to their specific survival rate from 2011 to 2013 to high (percentile >P75), intermediate (P25-P75) and low (

Asunto(s)
Recien Nacido Extremadamente Prematuro , Unidades de Cuidado Intensivo Neonatal/estadística & datos numéricos , Atención Perinatal/métodos , Atención Perinatal/estadística & datos numéricos , Mortalidad Perinatal/tendencias , Causas de Muerte , Comorbilidad , Femenino , Edad Gestacional , Estado de Salud , Humanos , Lactante , Recién Nacido , Recién Nacido de muy Bajo Peso , Masculino , Estudios Prospectivos , Mejoramiento de la Calidad , Factores de Riesgo , Factores Sexuales , Centros de Atención Terciaria
12.
Nucleic Acids Res ; 34(2): 462-71, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16421273

RESUMEN

DNA geminiviruses are thought to be targets of RNA silencing. Here, we characterize small interfering (si) RNAs-the hallmarks of silencing-associated with Cabbage leaf curl begomovirus in Arabidopsis and African cassava mosaic begomovirus in Nicotiana benthamiana and cassava. We detected 21, 22 and 24 nt siRNAs of both polarities, derived from both the coding and the intergenic regions of these geminiviruses. Genetic evidence showed that all the 24 nt and a substantial fraction of the 22 nt viral siRNAs are generated by the dicer-like proteins DCL3 and DCL2, respectively. The viral siRNAs were 5' end phosphorylated, as shown by phosphatase treatments, and methylated at the 3'-nucleotide, as shown by HEN1 miRNA methylase-dependent resistance to beta-elimination. Similar modifications were found in all types of endogenous and transgene-derived siRNAs tested, but not in a major fraction of siRNAs from a cytoplasmic RNA tobamovirus. We conclude that several distinct silencing pathways are involved in DNA virus-plant interactions.


Asunto(s)
Geminiviridae/genética , Plantas/virología , ARN Interferente Pequeño/metabolismo , ARN Viral/metabolismo , Arabidopsis/virología , Proteínas de Arabidopsis/metabolismo , Metilación , Fosforilación , Interferencia de ARN , Virus ARN/genética , ARN Interferente Pequeño/química , ARN Interferente Pequeño/clasificación , ARN Viral/química , ARN Viral/clasificación , Nicotiana/virología
13.
Nucleic Acids Res ; 34(21): 6233-46, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17090584

RESUMEN

Like other eukaryotes, plants use DICER-LIKE (DCL) proteins as the central enzymes of RNA silencing, which regulates gene expression and mediates defense against viruses. But why do plants like Arabidopsis express four DCLs, a diversity unmatched by other kingdoms? Here we show that two nuclear DNA viruses (geminivirus CaLCuV and pararetrovirus CaMV) and a cytoplasmic RNA tobamovirus ORMV are differentially targeted by subsets of DCLs. DNA virus-derived small interfering RNAs (siRNAs) of specific size classes (21, 22 and 24 nt) are produced by all four DCLs, including DCL1, known to process microRNA precursors. Specifically, DCL1 generates 21 nt siRNAs from the CaMV leader region. In contrast, RNA virus infection is mainly affected by DCL4. While the four DCLs are partially redundant for CaLCuV-induced mRNA degradation, DCL4 in conjunction with RDR6 and HEN1 specifically facilitates extensive virus-induced silencing in new growth. Additionally, we show that CaMV infection impairs processing of endogenous RDR6-derived double-stranded RNA, while ORMV prevents HEN1-mediated methylation of small RNA duplexes, suggesting two novel viral strategies of silencing suppression. Our work highlights the complexity of virus interaction with host silencing pathways and suggests that DCL multiplicity helps mediate plant responses to diverse viral infections.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Silenciador del Gen , Enfermedades de las Plantas/virología , Virus de Plantas/genética , ARN Interferente Pequeño/metabolismo , Ribonucleasa III/metabolismo , Arabidopsis/enzimología , Arabidopsis/genética , Arabidopsis/virología , Proteínas de Arabidopsis/genética , Caulimovirus/genética , Geminiviridae/genética , MicroARNs/metabolismo , Mutación , ARN Bicatenario/metabolismo , ARN Interferente Pequeño/clasificación , ARN Viral/clasificación , ARN Viral/metabolismo , Ribonucleasa III/genética , Tobamovirus/genética
14.
Mol Plant Microbe Interact ; 20(12): 1545-54, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17990962

RESUMEN

The Begomovirus transcriptional activator protein (TrAP/AC2/C2) is a multifunctional protein which activates the viral late gene promoters, suppresses gene silencing, and determines pathogenicity. To study TrAP-mediated transactivation of a stably integrated gene, we generated transgenic tobacco plants with a Mungbean yellow mosaic virus (MYMV) AV1 late gene promoter-driven reporter gene and supertransformed them with the MYMV TrAP gene driven by a strong 35S promoter. We obtained a single supertransformed plant with an intact 35S-TrAP gene that activated the reporter gene 2.5-fold. However, 10 of the 11 supertransformed plants did not have the TrAP region of the T-DNA, suggesting the likely toxicity of TrAP in plants. Upon transformation of wild-type tobacco plants with the TrAP gene, six of the seven transgenic plants obtained had truncated T-DNAs which lacked TrAP. One plant, which had the intact TrAP gene, did not express TrAP. The apparent toxic effect of the TrAP transgene was abolished by mutations in its nuclear-localization signal or zinc-finger domain and by deletion of its activation domain. Therefore, all three domains of TrAP, which are required for transactivation and suppression of gene silencing, also are needed for its toxic effect.


Asunto(s)
Begomovirus/patogenicidad , Nicotiana/genética , Plantas Modificadas Genéticamente/virología , Transactivadores/fisiología , Transgenes , Proteínas Virales/metabolismo , Begomovirus/genética , Begomovirus/metabolismo , Regiones Promotoras Genéticas , Nicotiana/virología , Transactivadores/genética , Proteínas Virales/genética
15.
Virus Res ; 119(1): 52-62, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16325949

RESUMEN

While translation of mRNAs in eukaryotic cells in general follows strict rules, viruses infecting these cells break those rules in various ways. Viruses are under high selection pressure to compete with the host, to economize genome size, and to accommodate signals for replication, virus assembly, etc., on their RNAs as well as using them for translation. The cornucopia of extraordinary translation strategies, such as leaky scanning, internal initiation of translation, ribosome shunt, and virus-controlled reinitiation of translation, evolved by viruses continues to surprise and inform our understanding of general translation mechanisms. While internal initiation is treated in another section of this issue, we concentrate on leaky scanning, shunt and reinitiation, with emphasis on plant pararetroviruses.


Asunto(s)
Iniciación de la Cadena Peptídica Traduccional , Virus de Plantas/genética , Ribosomas/metabolismo , Codón , Virus de Plantas/metabolismo , Biosíntesis de Proteínas , ARN Viral/genética , ARN Viral/metabolismo , Ribosomas/genética
16.
Nucleic Acids Res ; 30(2): 497-506, 2002 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-11788712

RESUMEN

Downstream sequences influence activity of the rice tungro bacilliform virus (RTBV) promoter in protoplasts derived from cultured rice cells. We previously identified a DNA element located between positions +50 and +90 relative to the transcription start site to which rice nuclear proteins bind. In this study, using DNA UV crosslinking assays, we show that two rice nuclear proteins bind specifically to this DNA element. We demonstrate that the DNA element enhances RTBV promoter activity in a copy number-dependent manner when transferred to a position upstream of the promoter. In addition, using electrophoretic mobility shift assays, we show that at least two novel nuclear proteins from rice cell suspension cultures bind to a subregion (from +50 to +59) of the DNA element and that a protein from rice root, but not shoot, nuclear extracts interacts with a perfect palindromic sequence motif located within the sequence +45 to +59. Furthermore, a position-dependent GAGA motif, present in three copies within downstream promoter sequences from +1 to +50, is involved in the regulation of RTBV promoter activity.


Asunto(s)
Badnavirus/genética , Regulación Viral de la Expresión Génica , Oryza/virología , Regiones Promotoras Genéticas/genética , Eliminación de Secuencia/genética , Transcripción Genética/genética , Secuencia de Bases , Sitios de Unión , Extractos Celulares , Células Cultivadas , Huella de ADN , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/metabolismo , Ensayo de Cambio de Movilidad Electroforética , Elementos de Facilitación Genéticos/genética , Peso Molecular , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Especificidad de Órganos , Oryza/citología , Fenantrolinas , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Raíces de Plantas/citología , Brotes de la Planta/citología , Unión Proteica , Protoplastos/virología , Rayos Ultravioleta
17.
Artículo en Inglés | MEDLINE | ID: mdl-12206450

RESUMEN

Due to the compactness of their genomes, viruses are well suited to the study of basic expression mechanisms, including details of transcription, RNA processing, transport, and translation. In fact, most basic principles of these processes were first described in viral systems. Furthermore, viruses seem not to respect basic rules, and cases of "abnormal" expression strategies are quiet common, although such strategies are usually also finally observed in rare cases of cellular gene expression. Concerning translation, viruses most often violate Kozak's original rule that eukaryotic translation starts from a capped monocistronic mRNA and involves linear scanning to find the first suitable start codon. Thus, many viral cases have been described where translation is initiated from noncapped RNA, using an internal ribosome entry site. This review centers on other viral translation strategies, namely shunting and virus-controlled reinitiation as first described in plant pararetroviruses (Caulimoviridae). In shunting, major parts of a complex leader are bypassed and not melted by scanning ribosomes. In the Caulimoviridae, this process is coupled to reinitiation after translation of a small open reading frame; in other cases, it is possibly initiated upon pausing of the scanning ribosome. Most of the Caulimoviridae produce polycistronic mRNAs. Two basic mechanisms are used for their translation. Alternative translation of the downstream open reading frames in the bacilliform Caulimoviridae occurs by a leaky scanning mechanism, and reinitiation of polycistronic translation in many of the icosahedral Caulimoviridae is enabled by the action of a viral transactivator. Both of these processes are discussed here in detail and compared to related processes in other viruses and cells.


Asunto(s)
Biosíntesis de Proteínas/fisiología , Ribosomas/fisiología , Fenómenos Fisiológicos de los Virus , Animales , Células Eucariotas , Genes , Humanos , Retroviridae/fisiología
18.
Viruses ; 8(6)2016 06 22.
Artículo en Inglés | MEDLINE | ID: mdl-27338451

RESUMEN

Badnaviruses (Family: Caulimoviridae; Genus: Badnavirus) are non-enveloped bacilliform DNA viruses with a monopartite genome containing about 7.2 to 9.2 kb of dsDNA with three to seven open reading frames. They are transmitted by mealybugs and a few species by aphids in a semi-persistent manner. They are one of the most important plant virus groups and have emerged as serious pathogens affecting the cultivation of several horticultural crops in the tropics, especially banana, black pepper, cocoa, citrus, sugarcane, taro, and yam. Some badnaviruses are also known as endogenous viruses integrated into their host genomes and a few such endogenous viruses can be awakened, e.g., through abiotic stress, giving rise to infective episomal forms. The presence of endogenous badnaviruses poses a new challenge for the fool-proof diagnosis, taxonomy, and management of the diseases. The present review aims to highlight emerging disease problems, virus characteristics, transmission, and diagnosis of badnaviruses.


Asunto(s)
Badnavirus/fisiología , Badnavirus/patogenicidad , Enfermedades de las Plantas/virología , Abastecimiento de Alimentos
19.
Viruses ; 8(10)2016 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-27690084

RESUMEN

The major threat for cassava cultivation on the Indian subcontinent is cassava mosaic disease (CMD) caused by cassava mosaic geminiviruses which are bipartite begomoviruses with DNA A and DNA B components. Indian cassava mosaic virus (ICMV) and Sri Lankan cassava mosaic virus (SLCMV) cause CMD in India. Two isolates of SLCMV infected the cassava cultivar Sengutchi in the fields near Malappuram and Thiruvananthapuram cities of Kerala State, India. The Malappuram isolate was persistent when maintained in the Madurai Kamaraj University (MKU, Madurai, Tamil Nadu, India) greenhouse, whereas the Thiruvananthapuram isolate did not persist. The recovered cassava plants with the non-persistent SLCMV, which were maintained vegetative in quarantine in the University of Basel (Basel, Switzerland) greenhouse, displayed re-emergence of CMD after a six-month period. Interestingly, these plants did not carry SLCMV but carried ICMV. It is interpreted that the field-collected, SLCMV-infected cassava plants were co-infected with low levels of ICMV. The loss of SLCMV in recovered cassava plants, under greenhouse conditions, then facilitated the re-emergence of ICMV. The partial dimer clones of the persistent and non-persistent isolates of SLCMV and the re-emerged isolate of ICMV were infective in Nicotiana benthamiana upon agroinoculation. Studies on pseudo-recombination between SLCMV and ICMV in N. benthamiana provided evidence for trans-replication of ICMV DNA B by SLCMV DNA A.

20.
PLoS One ; 11(7): e0159821, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27472282

RESUMEN

INTRODUCTION: In the German Neonatal Network (GNN) 10% of very-low-birth weight infants (VLBWI) suffer from blood-culture confirmed sepsis, while 30% of VLBWI develop clinical sepsis. Diagnosis of sepsis is a difficult task leading to potential over-treatment with antibiotics. This study aims to investigate whether the results of blood multiplex-PCR (SeptiFast®) for common sepsis pathogens are relevant for clinical decision making when sepsis is suspected in VLBWI. METHODS: We performed a prospective, multi-centre study within the GNN including 133 VLBWI with 214 episodes of suspected late onset sepsis (LOS). In patients with suspected sepsis a multiplex-PCR (LightCycler SeptiFast MGRADE-test®) was performed from 100 µl EDTA blood in addition to center-specific laboratory biomarkers. The attending neonatologist documented whether the PCR-result, which was available after 24 to 48 hrs, had an impact on the choice of antibiotic drugs and duration of therapy. RESULTS: PCR was positive in 110/214 episodes (51%) and blood culture (BC) was positive in 55 episodes (26%). Both methods yielded predominantly coagulase-negative staphylococci (CoNS) followed by Escherichia coli and Staphylococcus aureus. In 214 BC-PCR paired samples concordant results were documented in 126 episodes (59%; n = 32 were concordant pathogen positive results, n = 94 were negative in both methods). In 65 episodes (30%) we found positive PCR results but negative BCs, with CoNS being identified in 43 (66%) of these samples. Multiplex-PCR results influenced clinical decision making in 30% of episodes, specifically in 18% for the choice of antimicrobial therapy and in 22% for the duration of antimicrobial therapy. CONCLUSIONS: Multiplex-PCR results had a moderate impact on clinical management in about one third of LOS-episodes. The main advantage of multiplex-PCR was the rapid detection of pathogens from micro-volume blood samples. In VLBWI limitations include risk of contamination, lack of resistance testing and high costs. The high rate of positive PCR results in episodes of negative BC might lead to overtreatment of infants which is associated with risk of mortality, antibiotic resistance, fungal sepsis and NEC.


Asunto(s)
Enfermedades del Recién Nacido/microbiología , Recién Nacido de muy Bajo Peso/sangre , Sepsis/microbiología , Femenino , Alemania , Humanos , Recién Nacido , Enfermedades del Recién Nacido/sangre , Masculino , Reacción en Cadena de la Polimerasa Multiplex , Estudios Prospectivos , Sepsis/sangre , Manejo de Especímenes
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