Surgical complications and technical failure of simultaneous pancreas-kidney transplantation: A 22-year experience from a single center.

Simultaneous pancreas-kidney transplantation (SPKT) is the best treatment for selected individuals with type 1 diabetes mellitus and end-stage renal disease. Despite advances in surgical techniques, donor and recipient selection, and immunosuppressive therapies, SPKT remains a complex procedure with associated surgical complications and adverse consequences. We conducted a retrospective study that included 263 SPKT procedures performed between May 2000, and December 2022. A total of 65 patients (25%) required at least one relaparotomy, resulting in an all-cause relaparotomy rate of 2.04 events per 100 in-hospital days. Lower donor body mass index was identified as an independent factor associated with reoperation (OR .815; 95% CI:  .725-.917, p = .001). Technical failure (TF) occurred in 9.9% of cases, primarily attributed to pancreas graft thrombosis, intra-abdominal infections, bleeding, and anastomotic leaks. Independent predictors of TF at 90 days included donor age above 36 years (HR 2.513; 95% CI 1.162-5.434), previous peritoneal dialysis (HR 2.503; 95% CI 1.149-5.451), and specific pancreas graft reinterventions. The findings highlight the importance of carefully considering donor and recipient factors in SPKT. The incidence of TF in our study population aligns with the recent series. Continuous efforts should focus on identifying and mitigating potential risk factors to enhance SPKT outcomes, thereby reducing post-transplant complications.

Proteomics Uncovers Novel Components of an Interactive Protein Network Supporting RNA Export in Trypanosomes.

In trypanosomatids, transcription is polycistronic and all mRNAs are processed by trans-splicing, with export mediated by noncanonical mechanisms. Although mRNA export is central to gene regulation and expression, few orthologs of proteins involved in mRNA export in higher eukaryotes are detectable in trypanosome genomes, necessitating direct identification of protein components. We previously described conserved mRNA export pathway components in Trypanosoma cruzi, including orthologs of Sub2, a component of the TREX complex, and eIF4AIII (previously Hel45), a core component of the exon junction complex (EJC). Here, we searched for protein interactors of both proteins using cryomilling and mass spectrometry. Significant overlap between TcSub2 and TceIF4AIII-interacting protein cohorts suggests that both proteins associate with similar machinery. We identified several interactions with conserved core components of the EJC and multiple additional complexes, together with proteins specific to trypanosomatids. Additional immunoisolations of kinetoplastid-specific proteins both validated and extended the superinteractome, which is capable of supporting RNA processing from splicing through to nuclear export and cytoplasmic events. We also suggest that only proteomics is powerful enough to uncover the high connectivity between multiple aspects of mRNA metabolism and to uncover kinetoplastid-specific components that create a unique amalgam to support trypanosome mRNA maturation.

An influenza virus-triggered SUMO switch orchestrates co-opted endogenous retroviruses to stimulate host antiviral immunity.

Dynamic small ubiquitin-like modifier (SUMO) linkages to diverse cellular protein groups are critical to orchestrate resolution of stresses such as genome damage, hypoxia, or proteotoxicity. Defense against pathogen insult (often reliant upon host recognition of "non-self" nucleic acids) is also modulated by SUMO, but the underlying mechanisms are incompletely understood. Here, we used quantitative SILAC-based proteomics to survey pan-viral host SUMOylation responses, creating a resource of almost 600 common and unique SUMO remodeling events that are mounted during influenza A and B virus infections, as well as during viral innate immune stimulation. Subsequent mechanistic profiling focused on a common infection-induced loss of the SUMO-modified form of TRIM28/KAP1, a host transcriptional repressor. By integrating knockout and reconstitution models with system-wide transcriptomics, we provide evidence that influenza virus-triggered loss of SUMO-modified TRIM28 leads to derepression of endogenous retroviral (ERV) elements, unmasking this cellular source of "self" double-stranded (ds)RNA. Consequently, loss of SUMO-modified TRIM28 potentiates canonical cytosolic dsRNA-activated IFN-mediated defenses that rely on RIG-I, MAVS, TBK1, and JAK1. Intriguingly, although wild-type influenza A virus robustly triggers this SUMO switch in TRIM28, the induction of IFN-stimulated genes is limited unless expression of the viral dsRNA-binding protein NS1 is abrogated. This may imply a viral strategy to antagonize such a host response by sequestration of induced immunostimulatory ERV dsRNAs. Overall, our data reveal that a key nuclear mechanism that normally prevents aberrant expression of ERV elements (ERVs) has been functionally co-opted via a stress-induced SUMO switch to augment antiviral immunity.

Structure-Guided Functional Annotation of the Influenza A Virus NS1 Protein Reveals Dynamic Evolution of the p85ß-Binding Site during Circulation in Humans.

Rational characterization of virulence and host-adaptive markers in the multifunctional influenza A virus NS1 protein is hindered by a lack of comprehensive knowledge about NS1-host protein protein interfaces. Here, we surveyed the impact of amino acid variation in NS1 at its structurally defined binding site for host p85ß, a regulator of phosphoinositide 3-kinase (PI3K) signaling. Structure-guided alanine scanning of all viral residues at this interface defined 10 positions contributing to the interaction, with residues 89, 95, 98, 133, 145, and 162 being the most important. A bioinformatic study of >24,000 publicly available NS1 sequences derived from viruses infecting different hosts highlighted several prevalent amino acid variants at the p85ß interface that either enhanced (I95) or weakened (N135, T145, L161, Y161, S164) p85ß binding. Interestingly, analysis of viruses circulating in humans since the 1918 pandemic revealed the temporal acquisition of functionally relevant variants at this interface. I95 (which enhanced p85ß binding) quickly became prevalent in the 1940s and experimentally conferred a fitness advantage to a recombinant 1930s-based H1N1 virus in human lung epithelial cells. Surprisingly, H1N1 and H3N2 viruses recently acquired T145 or N135, respectively, which diminished p85ß binding but apparently not the overall fitness in the human population. Evolutionary analyses revealed covariation of the NS1-p85ß binding phenotype in humans with functional changes at multiple residues in other viral proteins, suggesting an unexplored compensatory or synergistic interplay between phenotypes in vivo Overall, our data provide a resource to understand the consequences of the NS1-p85ß binding spectrum of different influenza viruses and highlight the dynamic evolution of this property in viruses circulating in humans.IMPORTANCE In humans, influenza A viruses are responsible for causing seasonal epidemics and occasional pandemics. These viruses also circulate and evolve in other animal species, creating a reservoir from which novel viruses with distinct properties can emerge. The viral nonstructural protein NS1 is an important host range determinant and virulence factor that exhibits strain-specific interactions with several host factors, although few have been characterized extensively. In the study described here, we comprehensively surveyed the impact of natural and unnatural NS1 variations on the binding of NS1 to host p85ß, a subunit of phosphoinositide 3-kinase that regulates intracellular metabolism and contributes to virus replication and virulence. We define the p85ß-binding site on NS1 and provide a predictive resource to assess this ability of NS1 in viruses from different hosts. Strikingly, we uncover a spectrum of p85ß binding by different NS1 proteins and reveal that viruses evolving in humans have undergone dynamic changes in this NS1 function over the last century.

Genetic characterization of Rio de Janeiro for different Y-STR sets.

In this work, the YfilerPlus kit was used to investigate a sample of 258 males from Rio de Janeiro. In addition, the previous database of 760 Yfiler profiles deposited in the YHRD was updated to 1610. YfilerPlus markers showed a high haplotype diversity (0.99997), with only one haplotype shared by two individuals. When only considering the Yfiler markers, the haplotype diversity was slightly lower (0.99976), with 5 haplotypes shared by two individuals and 1 haplotype shared by three individuals. Low genetic distances were found between the Rio de Janeiro and European populations as well as the European/Hispanic American samples.

Novel Role for Protein Inhibitor of Activated STAT 4 (PIAS4) in the Restriction of Herpes Simplex Virus 1 by the Cellular Intrinsic Antiviral Immune Response.

UNLABELLED: Small ubiquitin-like modifier (SUMO) is used by the intrinsic antiviral immune response to restrict viral pathogens, such as herpes simplex virus 1 (HSV-1). Despite characterization of the host factors that rely on SUMOylation to exert their antiviral effects, the enzymes that mediate these SUMOylation events remain to be defined. We show that unconjugated SUMO levels are largely maintained throughout infection regardless of the presence of ICP0, the HSV-1 SUMO-targeted ubiquitin ligase. Moreover, in the absence of ICP0, high-molecular-weight SUMO-conjugated proteins do not accumulate if HSV-1 DNA does not replicate. These data highlight the continued importance for SUMO signaling throughout infection. We show that the SUMO ligase protein inhibitor of activated STAT 4 (PIAS4) is upregulated during HSV-1 infection and localizes to nuclear domains that contain viral DNA. PIAS4 is recruited to sites associated with HSV-1 genome entry through SUMO interaction motif (SIM)-dependent mechanisms that are destabilized by ICP0. In contrast, PIAS4 accumulates in replication compartments through SIM-independent mechanisms irrespective of ICP0 expression. Depletion of PIAS4 enhances the replication of ICP0-null mutant HSV-1, which is susceptible to restriction by the intrinsic antiviral immune response. The mechanisms of PIAS4-mediated restriction are synergistic with the restriction mechanisms of a characterized intrinsic antiviral factor, promyelocytic leukemia protein, and are antagonized by ICP0. We provide the first evidence that PIAS4 is an intrinsic antiviral factor. This novel role for PIAS4 in intrinsic antiviral immunity contrasts with the known roles of PIAS proteins as suppressors of innate immunity. IMPORTANCE: Posttranslational modifications with small ubiquitin-like modifier (SUMO) proteins regulate multiple aspects of host immunity and viral replication. The protein inhibitor of activated STAT (PIAS) family of SUMO ligases is predominantly associated with the suppression of innate immune signaling. We now identify a unique and contrasting role for PIAS proteins as positive regulators of the intrinsic antiviral immune response to herpes simplex virus 1 (HSV-1) infection. We show that PIAS4 relocalizes to nuclear domains that contain viral DNA throughout infection. Depletion of PIAS4, either alone or in combination with the intrinsic antiviral factor promyelocytic leukemia protein, significantly impairs the intrinsic antiviral immune response to HSV-1 infection. Our data reveal a novel and dynamic role for PIAS4 in the cellular-mediated restriction of herpesviruses and establish a new functional role for the PIAS family of SUMO ligases in the intrinsic antiviral immune response to DNA virus infection.

Molecular and Genomic Alterations in Glioblastoma Multiforme.

In recent years, important advances have been achieved in the understanding of the molecular biology of glioblastoma multiforme (GBM); thus, complex genetic alterations and genomic profiles, which recurrently involve multiple signaling pathways, have been defined, leading to the first molecular/genetic classification of the disease. In this regard, different genetic alterations and genetic pathways appear to distinguish primary (eg, EGFR amplification) versus secondary (eg, IDH1/2 or TP53 mutation) GBM. Such genetic alterations target distinct combinations of the growth factor receptor-ras signaling pathways, as well as the phosphatidylinositol 3-kinase/phosphatase and tensin homolog/AKT, retinoblastoma/cyclin-dependent kinase (CDK) N2A-p16(INK4A), and TP53/mouse double minute (MDM) 2/MDM4/CDKN2A-p14(ARF) pathways, in cells that present features associated with key stages of normal neurogenesis and (normal) central nervous system cell types. This translates into well-defined genomic profiles that have been recently classified by The Cancer Genome Atlas Consortium into four subtypes: classic, mesenchymal, proneural, and neural GBM. Herein, we review the most relevant genetic alterations of primary versus secondary GBM, the specific signaling pathways involved, and the overall genomic profile of this genetically heterogeneous group of malignant tumors.

Tumor infiltrating immune cells in gliomas and meningiomas.

Tumor-infiltrating immune cells are part of a complex microenvironment that promotes and/or regulates tumor development and growth. Depending on the type of cells and their functional interactions, immune cells may play a key role in suppressing the tumor or in providing support for tumor growth, with relevant effects on patient behavior. In recent years, important advances have been achieved in the characterization of immune cell infiltrates in central nervous system (CNS) tumors, but their role in tumorigenesis and patient behavior still remain poorly understood. Overall, these studies have shown significant but variable levels of infiltration of CNS tumors by macrophage/microglial cells (TAM) and to a less extent also lymphocytes (particularly T-cells and NK cells, and less frequently also B-cells). Of note, TAM infiltrate gliomas at moderate numbers where they frequently show an immune suppressive phenotype and functional behavior; in contrast, infiltration by TAM may be very pronounced in meningiomas, particularly in cases that carry isolated monosomy 22, where the immune infiltrates also contain greater numbers of cytotoxic T and NK-cells associated with an enhanced anti-tumoral immune response. In line with this, the presence of regulatory T cells, is usually limited to a small fraction of all meningiomas, while frequently found in gliomas. Despite these differences between gliomas and meningiomas, both tumors show heterogeneous levels of infiltration by immune cells with variable functionality. In this review we summarize current knowledge about tumor-infiltrating immune cells in the two most common types of CNS tumors-gliomas and meningiomas-, as well as the role that such immune cells may play in the tumor microenvironment in controlling and/or promoting tumor development, growth and control.

Inhibition of hepatitis C virus RNA replication by ISG15 does not require its conjugation to protein substrates by the HERC5 E3 ligase.

Chronic infection of the liver by hepatitis C virus (HCV) induces a range of host factors including IFN-stimulated genes such as ISG15. ISG15 functions as an antiviral factor that limits virus replication. Previous studies have suggested that ISG15 could influence HCV replication in both a positive and a negative manner. In this report, we determined the effect of ISG15 on HCV RNA replication in two independent cell lines that support viral genome synthesis by inhibiting ISG15 expression through small interfering RNA, short-hairpin RNA and CRISPR/Cas9 gene knockout approaches. Our results demonstrated that ISG15 impairs HCV RNA replication in both the presence and absence of IFN stimulation, consistent with an antiviral role for ISG15 during HCV infection. ISG15 conjugation to protein substrates typically requires the E3 ligase, HERC5. Our results showed that the inhibitory effect of ISG15 on HCV RNA replication does not require its conjugation to substrates by HERC5.

A single amino acid substitution in the novel H7N9 influenza A virus NS1 protein increases CPSF30 binding and virulence.

Although an effective interferon antagonist in human and avian cells, the novel H7N9 influenza virus NS1 protein is defective at inhibiting CPSF30. An I106M substitution in H7N9 NS1 can restore CPSF30 binding together with the ability to block host gene expression. Furthermore, a recombinant virus expressing H7N9 NS1-I106M replicates to higher titers in vivo, and is subtly more virulent, than the parental virus. Natural polymorphisms in H7N9 NS1 that enhance CPSF30 binding may be cause for concern.

The protein expression profile of meningioma cells is associated with distinct cytogenetic tumour subgroups.

AIMS: Limited information exists about the impact of cytogenetic alterations on the protein expression profiles of individual meningioma cells and their association with the clinicohistopathological characteristics of the disease. The aim of this study is to investigate the potential association between the immunophenotypic profile of single meningioma cells and the most relevant features of the tumour. METHODS: Multiparameter flow cytometry (MFC) was used to evaluate the immunophenotypic profile of tumour cells (n = 51 patients) and the Affymetrix U133A chip was applied for the analysis of the gene expression profile (n = 40) of meningioma samples, cytogenetically characterized by interphase fluorescence in situ hybridization. RESULTS: Overall, a close association between the pattern of protein expression and the cytogenetic profile of tumour cells was found. Thus, diploid tumours displayed higher levels of expression of the CD55 complement regulatory protein, tumours carrying isolated monosomy 22/del(22q) showed greater levels of bcl2 and PDGFRß and meningiomas carrying complex karyotypes displayed a greater proliferation index and decreased expression of the CD13 ectoenzyme, the CD9 and CD81 tetraspanins, and the Her2/neu growth factor receptor. From the clinical point of view, higher expression of CD53 and CD44 was associated with a poorer outcome. CONCLUSIONS: Here we show that the protein expression profile of individual meningioma cells is closely associated with tumour cytogenetics, which may reflect the involvement of different signalling pathways in the distinct cytogenetic subgroups of meningiomas, with specific immunophenotypic profiles also translating into a different tumour clinical behaviour.

Renal Artery Stenosis in Living Donor Kidney Transplantation: A Rare Cause of "Flash Edema".

Transplant renal artery stenosis (TRAS) is a well-recognized vascular complication after kidney transplantation, with an incidence ranging from 1% to 23%. TRAS often presents with clinical features such as refractory hypertension, de novo hypertension, allograft dysfunction, and the presence of a bruit over the graft. A rare manifestation of TRAS is flash pulmonary edema. Here, we present a case of a 37-year-old male who received a living donor kidney. Four years after the transplant, he presented with acute kidney injury, hypertensive crisis, and flash pulmonary edema. Initially, methylprednisolone pulses were administered due to suspicion of acute rejection, which was later ruled out after a kidney graft biopsy. Computed tomography angiography showed findings suggesting stenosis or thrombus in the renal artery. The patient developed sudden acute pulmonary edema, requiring hemodialysis, with notable clinical improvement. Subsequently, stent placement was performed without complications, resulting in the complete recovery of renal function and effective blood pressure control. The incidence of renal artery stenosis is higher in living donor kidney transplantation, mainly due to technical complexities during surgery. Acute presentations, such as flash edema, are exceptionally rare but can occur years after transplantation. Prompt intervention can lead to favorable outcomes.

Immunophenotypic identification and characterization of tumor cells and infiltrating cell populations in meningiomas.

Meningiomas are primary tumors of the central nervous system composed of both neoplastic and other infiltrating cells. We determined the cellular composition of 51 meningioma samples by multiparameter flow cytometric (MFC) immunophenotyping and investigated the potential relationship between mRNA and protein expression levels of neoplastic cells. For immunophenotypic, morphologic, and cytogenetic characterization of individual cell populations, a large panel of markers was used together with phagocytic/endocytic functional assays and MFC sorting. Overall, our results revealed coexistence of CD45(-) neoplastic cells and CD45(+) immune infiltrating cells in all meningiomas. Infiltrating cells included tissue macrophages, with an HLA-DR(+)CD14(+)CD45(+)CD68(+)CD16(-/+)CD33(-/+) phenotype and high phagocytic/endocytic activity, and a small proportion of cytotoxic lymphocytes (mostly T CD8(+) and natural killer cells). Tumor cells expressed multiple cell adhesion proteins, tetraspanins, HLA-I/HLA-DR molecules, complement regulatory proteins, cell surface ectoenzymes, and growth factor receptors. Noteworthy, the relationship between mRNA and protein levels was variable, depending on the proteins evaluated and the level of infiltration by immune cells. In summary, our results indicate that MFC immunophenotyping provides a reliable tool for the characterization of the patterns of protein expression of different cell populations coexisting in meningioma samples, with a more accurate measure of gene expression profiles of tumor cells at the functional/protein level than conventional mRNA microarray, independently of the degree of infiltration of the tumor by immune cells.

Association between mutation of the NF2 gene and monosomy 22 in menopausal women with sporadic meningiomas.

BACKGROUND: Meningioma was the first solid tumor shown to contain a recurrent genetic alteration e.g. monosomy 22/del(22q), NF2 being the most relevant gene involved. Although monosomy 22/del(22q) is present in half of all meningiomas, and meningiomas frequently carry NF2 mutations, no study has been reported so far in which both alterations are simultaneously assessed and correlated with the features of the disease. METHODS: Here, we analyzed the frequency of both copy number changes involving chromosome 22 and NF2 mutations in 20 sporadic meningiomas using high-density SNP-arrays, interphase-FISH and PCR techniques. RESULTS: Our results show a significant frequency of NF2 mutations (6/20 patients, 30%), most of which (5/6) had not been previously reported in sporadic meningiomas. NF2 mutations involved five different exons and led to a truncated protein (p.Leu163CysfsX46, p.Phe62LeufsX61, p.Asp281MetfsX15, p.Phe285LeufsX11, p.Gln389ArgfsX37) and an in frame deletion of Phe119. Interestingly, all NF2 mutated cases were menopausal women with monosomy 22 but not del(22q). CONCLUSIONS: These results confirm and extend on previous observations about the high frequency and heterogeneity of NF2 mutations in sporadic meningiomas and indicate they could be restricted to a well-defined cytogenetic and clinical subgroup of menopausal women. Further studies in large series of patients are required to confirm our observations.

Selective cultures for the isolation of biosurfactant producing bacteria: comparison of different combinations of environmental inocula and hydrophobic carbon sources.

The potential of estuarine microniches as reservoirs of biosurfactant-producing bacteria was evaluated by testing different combinations of inocula and hydrophobic carbon sources. Selective cultures using diesel, petroleum, or paraffin as hydrophobic carbon sources were prepared and inoculated with water from the surface microlayer, bulk sediments, and sediment of the rhizosphere of Halimione portulacoides. These inocula were compared regarding the frequency of biosurfactant-producing strains among selected isolates. The community structure of the selective cultures was profiled using denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene fragments at the end of the incubation. The DGGE profiles corresponding to the communities established in selective cultures at the end of the incubation revealed that communities were different in terms of structural diversity. The highest diversity was observed in the selective cultures containing paraffin (H (') = 2.5). Isolates were obtained from the selective cultures (66) and tested for biosurfactant production by the atomized oil assay. Biosurfactant production was detected in 17 isolates identified as Microbacterium, Pseudomonas, Rhodococcus, and Serratia. The combination of estuarine surface microlayer (SML) water as inoculum and diesel as carbon source seems promising for the isolation of surfactant-producing bacteria. Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.

Under-Recognized Pathogens in Peritoneal Dialysis Associated-Peritonitis: The Importance of Early Detection.

Peritoneal dialysis-associated-peritonitis remains a major concern, increasing patient morbidity and mortality. Empirical antibiotics should be quickly started to allow a rapid resolution of symptoms and preservation of the peritoneal membrane. We report a case of peritoneal dialysis-associated-peritonitis due to Prevotella salivae and Corynebacterium jeikeium, in a 51-year-old male. Suspected peritonitis led to an immediate prescription of vancomycin and ceftazidime, with no clinical improvement. Prevotella is difficult to identify in culture since it's a gram-negative anaerobic bacterium, so metronidazole administration was delayed over days. New diagnostic techniques have been explored for the early diagnosis of peritonitis, including polymerase chain reaction (PCR) for bacterial DNA fragments. A multiplex PCR panel that includes Prevotella, already available for other applications, could be an advantage in cases like this.

Persistent Left Superior Vena Cava: Rare Location of Hemodialysis Catheter.

When the left cardinal vein fails to involute during fetal life, a persistent left superior vena cava (PLSVC) develops. PLSVC is a rare vascular anomaly, and the reported incidence is 0.3-0.5% in healthy individuals. It is usually asymptomatic and does not cause hemodynamic disturbances unless associated with cardiac malformations. If the PLSVC drains adequately into the right atrium and there are no cardiac abnormalities, catheterization of this vessel, including temporary and cuffed HD catheter insertion, is deemed safe. We present the case of a 70-year-old woman with acute kidney injury (AKI), in which the necessity to place an HD central venous catheter (CVC) through the left internal jugular vein led to the discovery of a PLSVC. Once it was shown that the vessel was adequately draining into the right atrium, this catheter was changed to a cuffed tunneled HD catheter, which was successfully utilized for HD sessions for three months and removed after the recuperation of renal function without complications.

A Rare and Severe Cause of Abdominal Pain in a Hemodialysis Patient.

Pneumatosis intestinalis (PI) and aeroportia have been rarely described in hemodialysis patients. We present a case of a 64-year-old woman on regular hemodialysis who presented with abdominal pain, vomiting, and diarrhea. Abdominal CT showed pneumatosis intestinalis and aeroportia suggestive of ischemic abnormalities. In this case, given the absence of transmural necrosis or bowel perforation, aeroportia seemed to be caused by nonocclusive mesenteric ischemia (NOMI), an increasingly recognized complication in hemodialysis patients. The patient was proposed for emergent exploratory laparotomy; however, she had a fatal outcome. Hemodialysis-dependent patients should be considered at risk of the "low-flow syndrome" of mesenteric arterial circulation. Prevention is crucial, and early detection of these entities is important for prompt diagnosis and management of mesenteric ischemia.

Comparison of U2OS and Huh-7 cells for identifying host factors that affect hepatitis C virus RNA replication.

Host cell factors are critical to all stages of the hepatitis C virus (HCV) life cycle. While many cellular proteins that regulate HCV genome synthesis have been identified, the mechanisms engaged in this process are incompletely understood. To identify novel cellular proteins involved in HCV RNA replication, we screened a library of small interfering RNAs (siRNAs) targeting 299 cellular factors, which principally function in RNA interactions. For the screen, a robust system was established using two cell lines (derived from Huh-7 and U2OS cells) that replicated tricistronic subgenomic replicons (SGRs). We found that the U2OS cell line gave lower levels of intracellular HCV RNA replication compared with Huh-7 cells and was more readily transfected by siRNAs. Consequently, increased gene silencing and greater effects on HCV replication were observed in the U2OS cell line. Thus, U2OS cells provided a suitable and more sensitive alternative to Huh-7 cells for siRNA studies on HCV RNA replication. From the screen, several cellular proteins that enhanced and suppressed HCV RNA replication were identified. One of the genes found to downregulate viral RNA synthesis, ISG15, is expressed in response to alpha interferon and may therefore partly contribute to the clearance of virus from infected individuals. A second gene that inhibited HCV RNA levels was the 5'-3' exoRNase XRN1, which suggested a role for cellular RNA degradation pathways in modulating the abundance of viral genomes. Therefore, this study provides an important framework for future detailed analyses of these and other cellular proteins.

Biosurfactant Production in Sub-Oxic Conditions Detected in Hydrocarbon-Degrading Isolates from Marine and Estuarine Sediments.

Hydrocarbon bioremediation in anoxic sediment layers is still challenging not only because it involves metabolic pathways with lower energy yields but also because the production of biosurfactants that contribute to the dispersion of the pollutant is limited by oxygen availability. This work aims at screening populations of culturable hydrocarbonoclastic and biosurfactant (BSF) producing bacteria from deep sub-seafloor sediments (mud volcanos from Gulf of Cadiz) and estuarine sub-surface sediments (Ria de Aveiro) for strains with potential to operate in sub-oxic conditions. Isolates were retrieved from anaerobic selective cultures in which crude oil was provided as sole carbon source and different supplements were provided as electron acceptors. Twelve representative isolates were obtained from selective cultures with deep-sea and estuary sediments, six from each. These were identified by sequencing of 16S rRNA gene fragments belonging to Pseudomonas, Bacillus, Ochrobactrum, Brevundimonas, Psychrobacter, Staphylococcus, Marinobacter and Curtobacterium genera. BSF production by the isolates was tested by atomized oil assay, surface tension measurement and determination of the emulsification index. All isolates were able to produce BSFs under aerobic and anaerobic conditions, except for isolate DS27 which only produced BSF under aerobic conditions. These isolates presented potential to be applied in bioremediation or microbial enhanced oil recovery strategies under conditions of oxygen limitation. For the first time, members of Ochrobactrum, Brevundimonas, Psychrobacter, Staphylococcus, Marinobacter and Curtobacterium genera are described as anaerobic producers of BSFs.