Minimal information on the genome and proteome of Schistosoma haematobium is available, in marked contrast to the situation with the other major species of human schistosomes for which draft genome ...sequences have been reported. Accordingly, little is known about functional genomics in S. haematobium, including the utility or not of RNA interference techniques that, if available, promise to guide development of new interventions for schistosomiasis haematobia.
Here we isolated and cultured developmental stages of S. haematobium, derived from experimentally infected hamsters. Targeting different developmental stages, we investigated the utility of soaking and/or square wave electroporation in order to transfect S. haematobium with nucleic acid reporters including Cy3-labeled small RNAs, messenger RNA encoding firefly luciferase, and short interfering RNAs (siRNAs). Three hours after incubation of S. haematobium eggs in 50 ng/µl Cy3-labeled siRNA, fluorescent foci were evident indicating that labeled siRNA had penetrated into miracidia developing within the egg shell. Firefly luciferase activity was detected three hours after square wave electroporation of the schistosome eggs and adult worms in 150 ng/µl of mRNA. RNA interference knockdown (silencing) of reporter luciferase activity was seen following the introduction of dsRNA specific for luciferase mRNA in eggs, schistosomules and mixed sex adults. Moreover, introduction of an endogenous gene-specific siRNA into adult schistosomes silenced transcription of tetraspanin 2 (Sh-tsp-2), the apparent orthologue of the Schistosoma mansoni gene Sm-tsp-2 which encodes the surface localized structural and signaling protein Sm-TSP-2. Together, knockdown of reporter luciferase and Sh-tsp-2 indicated the presence of an intact RNAi pathway in S. haematobium. Also, we employed laser scanning confocal microscopy to view the adult stages of S. haematobium.
These findings and approaches should facilitate analysis of gene function in S. haematobium, which in turn could facilitate the characterization of prospective intervention targets for this neglected tropical disease pathogen.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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► Promoter of U6 gene of
Schistosoma mansoni. ► Episomal vector-based RNA interference (RNAi) in schistosomules. ► Short hairpin RNAi in schistosomes driven by U6 promoter.
RNA ...interference (RNAi) mediated by short hairpin-RNA (shRNA) expressing plasmids can induce specific and long-term knockdown of specific mRNAs in eukaryotic cells. To develop a vector-based RNAi model for
Schistosoma mansoni, the schistosome U6 gene promoter was employed to drive expression of shRNA targeting reporter firefly luciferase. An upstream region of a U6 gene predicted to contain the promoter was amplified from genomic DNA of
S. mansoni. A shRNA construct driven by the predicted U6 promoter targeting luciferase was assembled and cloned into plasmid pXL-Bac II, the construct termed pXL-BacII_SmU6-shLuc. Luciferase expression in transgenic fibrosarcoma HT-1080 cells was significantly reduced 96
h following transduction with plasmid pXL-BacII_SmU6-shLuc, which encodes luciferase mRNA-specific shRNA. In a similar fashion, schistosomules of
S. mansoni were transformed with the SmU6-shLuc or control constructs. Firefly luciferase mRNA was introduced into transformed schistosomules after which luciferase activity was analyzed. Significantly less activity was present in schistosomules transfected with pXL-BacII_SmU6-shLuc compared with controls. The findings revealed that the putative
S. mansoni U6 gene promoter of 270
bp in length was active in human cells and schistosomes. Given that the U6 gene promoter drove expression of shRNA from an episome, the findings also indicate the potential of this putative RNA polymerase III dependent promoter as a component regulatory element in vector-based RNAi for functional genomics of schistosomes.
Four lytic mycobacteriophages, namely, SynergyX, Abinghost, Bananafish, and Delton, were isolated from soil in Washington, DC, using the bacterial host Mycobacterium smegmatis mc
155. Analysis of the ...genomes revealed that they belong to two subclusters of actinobacteriophage cluster B (subclusters B2 and B3) and subcluster D1 of cluster D.
Blood flukes or schistosomes are the causative agents of human schistosomiasis, one of the major neglected tropical diseases. Draft genome sequences have been reported for schistosomes, but ...functional genomics tools are needed to investigate the role and essentiality of the newly reported genes. Vector based RNA interference can contribute to functional genomics analysis for schistosomes. Using mRNA encoding reporter firefly luciferase as a model target, we compared the performance of a schistosome and a human promoter from the U6 gene in driving shRNA in human fibrosarcoma cells and in cultured schistosomes. Further, both a retroviral Murine leukemia virus (MLV) and plasmid (piggyBac, pXL-Bac II) vector were utilized. The schistosome U6 gene promoter was 270 bp in length, the human U6 gene promoter was 264 bp; they shared 41% identity. Following transduction of both HT1080 fibrosarcoma cells and schistosomules of Schistosoma mansoni with pseudotyped MLV virions, stronger knockdown of luciferase activity was seen with the virions encoding the human U6 promoter driven shRNA than the schistosome U6 promoter. A similar trend was seen after transfection of HT1080 cells and schistosomules with the pXL-Bac-II constructs—stronger knockdown of luciferase activity was seen with constructs encoding the human compared to schistosome U6 promoter. The findings indicate that a human U6 gene promoter drives stronger shRNA activity than its schistosome orthologue, not only in a human cancer cell line but also in larval schistosomes. This RNA polymerase III promoter represents a potentially valuable component for vector based RNA interference studies in schistosomes and related platyhelminth parasites.
Two temperate mycobacteriophages, Dallas and Jonghyun, were isolated from soil in Washington, DC, using the bacterial host Mycobacterium smegmatis mc
155. Analysis of the genomes revealed that Dallas ...and Jonghyun belong to clusters J and G, respectively. The structures of the genomes are typical of their respective clusters.
Five subcluster C1 mycobacteriophages, Blackbrain, Cactojaque, Kboogie, Trinitium, and YoungMoneyMata, were isolated from soil using the host Mycobacterium smegmatis mc
155. The genome sizes range ...from 154,512 to 156,223 bp. The largest genome encodes 237 predicted proteins, 34 tRNAs, and 1 transfer-messenger RNA (tmRNA).
The African Union's Agenda 2063 and the Malabo Declaration recognize agricultural development as one of the most effective means of combating extreme poverty. Conservation Agriculture Practices (CAP) ...have been asserted to have the potential to boost agricultural output, improve livelihood and contribute to the conservation of natural resources. This study thus seeks to advance knowledge about Conversation Agriculture by assessing the factors determining the adoption and intensity of CAP among Cameroon's smallholder farmers. Data collected from 351 farmers in the South and East regions of Cameroon were used to study the social, economic, ecological and biophysical factors that determine the adoption of CAP. The study considered agroforestry, intercropping, crop rotation, cover crop, mulching, and zero-tillage as the CAP under investigation. According to the multivariate probit analysis employed, the results showed that gender, age, family size, extension services, use of modern farm technology, distance from house to farm, livestock owned, and infertile soil all significantly influenced CAP adoption. Results on adoption intensity revealed that gender, distance from house to farm, and the number of livestock owned were critical drivers of CAP adoption intensity. Promoting the adoption of CAP, policymakers and concerned stakeholders should consider farmer, institutional, socio-economic, ecological, biophysical aspects as well as relational values. However, already existing extension services need to be improved upon.
Chronic graft-versus-host disease (GVHD) commonly occurs after allogeneic hematopoietic cell transplantation (HCT) despite standard prophylactic immune suppression. Intensified universal prophylaxis ...approaches are effective but risk possible overtreatment and may interfere with the graft-versus-malignancy immune response. Here we summarize conceptual and practical considerations regarding preemptive therapy of chronic GVHD, namely interventions applied after HCT based on evidence that the risk of developing chronic GVHD is higher than previously appreciated. This risk may be anticipated by clinical factors or risk assignment biomarkers or may be indicated by early signs and symptoms of chronic GVHD that do not fully meet National Institutes of Health diagnostic criteria. However, truly preemptive, individualized, and targeted chronic GVHD therapies currently do not exist. In this report, we (1) review current knowledge regarding clinical risk factors for chronic GVHD, (2) review what is known about chronic GVHD risk assignment biomarkers, (3) examine how chronic GVHD pathogenesis intersects with available targeted therapeutic agents, and (4) summarize considerations for preemptive therapy for chronic GVHD, emphasizing trial development, including trial design and statistical considerations. We conclude that robust risk assignment models that accurately predict chronic GVHD after HCT and early-phase preemptive therapy trials represent the most urgent priorities for advancing this novel area of research.
Late acute (LA) graft-versus-host disease (GVHD) is persistent, recurrent, or new-onset acute GVHD symptoms occurring >100 days after allogeneic hematopoietic cell transplantation (HCT). The aim of ...this analysis is to describe the onset, course, morbidity, and mortality of and examine angiogenic factors associated with LA GVHD. A prospective cohort of patients (n = 909) was enrolled as part of an observational study within the Chronic GVHD Consortium. Eighty-three patients (11%) developed LA GVHD at a median of 160 (interquartile range, 128-204) days after HCT. Although 51 out of 83 (61%) achieved complete or partial response to initial therapy by 28 days, median failure-free survival was only 7.1 months (95% confidence interval, 3.4-19.1 months), and estimated overall survival (OS) at 2 years was 56%. Given recently described alterations of circulating angiogenic factors in classic acute GVHD, we examined whether alterations in such factors could be identified in LA GVHD. We first tested cases (n = 55) and controls (n = 50) from the Chronic GVHD Consortium and then validated the findings in 37 cases from Mount Sinai Acute GVHD International Consortium. Plasma amphiregulin (AREG; an epidermal growth factor EGF receptor ligand) was elevated, and an AREG/EGF ratio at or above the median was associated with inferior OS and increased nonrelapse mortality in both cohorts. Elevation of AREG was detected in classic acute GVHD, but not chronic GVHD. These prospective data characterize the clinical course of LA GVHD and demonstrate alterations in angiogenic factors that make LA GVHD biologically distinct from chronic GVHD.
•Under current treatment approaches, patients with LA GVHD have poor overall and failure-free survival.•Levels of AREG are elevated in LA GVHD, and the AREG/EGF ratio is predictive of overall survival and nonrelapse mortality in LA GVHD.
Amphiregulin (AREG) is an epidermal growth factor receptor ligand that can restore integrity to damaged intestinal mucosa in murine models of acute graft-versus-host disease (aGVHD). We previously ...reported that circulating AREG is elevated in late-onset aGVHD (occurring after 100 days posttransplant), but its clinical relevance in the context of aGVHD risk is unknown. We measured AREG in 251 aGVHD onset blood samples from Blood and Marrow Clinical Trials Network (BMT CTN) primary treatment trials and determined their association with GVHD severity, day 28 complete or partial response (CR/PR) to first-line therapy, overall survival (OS), and nonrelapse mortality (NRM). Every doubling of plasma AREG was associated with a 33% decrease in the odds of day 28 CR/PR (odds ratio OR, 0.67; P < .01). An AREG threshold of 33 pg/mL or greater divided patients with Minnesota standard-risk (SR) aGVHD into a distinct group with a significantly lower likelihood of: day 28 CR/PR (72% vs 85%; P = .02); greater 2-year NRM (42% vs 15%; P < .01); and inferior OS (40% vs 66%; P < .01). High AREG ≥ 33 pg/mL also stratified patients with Minnesota high-risk (HR) aGVHD: day 28 CR/PR (54% vs 83%; P = .03) and 2-year NRM (53% vs 11%; P < .01), with a trend toward inferior 2-year OS (37% vs 60%; P = .09). High-circulating AREG (≥33 pg/mL) reclassifies patients into HR subgroups and thereby further refines the Minnesota aGVHD clinical risk score.
•High-circulating AREG (≥33 pg/mL) reclassifies additional patients into HR categories and further refines the Minnesota aGVHD risk score.•Patients with aGVHD and AREG ≥33 pg/mL have lower rates of steroid response, higher NRM, and poorer OS.
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