Transcriptome characterisation of the intra-mammalian stage of male and female Schistosoma mansoni

Schistosoma mansoni is a member of a genus of platyhelminths whose members cause the disease schistosomiasis. Particularly prevalent in sub-Saharan Africa, it is thought to be directly responsible for approximately 5500 deaths per year, as well as contributing significantly to morbidity, being responsible for 3.3 million lost disability-adjusted life years. Schistosomes are dioecious and male and female worms find one another and pair in the blood vessels of the host’s liver. This sets in motion a unique feature of schistosome biology, the pairing-dependent sexual maturation of the female worms. Over the course of the next three weeks, the females fully develop their reproductive organs, especially ovaries and vitellarian tissue, to allow for the production of large quantities of eggs, which not only play a crucial role in the transmission of the parasites but are also responsible for much of the pathology associated with schistosomiasis. This thesis aims to explore the changes in gene expression which take place following pairing and result in the sexual maturation of females. To do so, RNA-Seq data was produced from male and female worms from mixed sex as well as single sex infections at 18, 21, 28, 35, 38 and 49 days post infection and analysed to understand when and how gene expression changes in paired worms. Then gene expression was examined in worms that had been removed from their partner to examine the process of regression, where female worms lose much of their reproductive tissue. The last experiments describe examine gene expression in the testes and ovaries of schistosomes, to reveal differences between the gonads of worms from mixed and single sex infections and understand in more detail how these worms may regulate the growth of their reproductive organs, contributing to our knowledge of schistosome biology.Wellcome Trus

Isoflurane promotes early spontaneous breathing in ventilated intensive care patients: A post hoc subgroup analysis of a randomized trial

Background: Spontaneous breathing is desirable in most ventilated patients. We therefore studied the influence of isoflurane versus propofol sedation on early spon taneous breathing in ventilated surgical intensive care patients and evaluated poten tial mediation by opioids and arterial carbon dioxide during the first 20 h of study sedation. Methods: We included a single-center subgroup of 66 patients, who participated in a large multi-center trial assessing efficacy and safety of isoflurane sedation, with 33 patients each randomized to isoflurane or propofol sedation. Both sedatives were titrated to a sedation depth of −4 to −1 on the Richmond Agitation Sedation Scale. The primary outcome was the fraction of time during which patients breathed spontaneously. Results: Baseline characteristics of isoflurane and propofol-sedated patients were well balanced. There were no substantive differences in management or treatment aside from sedation, and isoflurane and propofol provided nearly identical sedation depths. The mean fraction of time spent spontaneously breathing was 82% [95% CI: 69, 90] in patients sedated with isoflurane compared to 35% [95% CI: 22, 51] in those assigned to propofol: median difference: 61% [95% CI: 14, 89], p < .001. After ad justments for sufentanil dose and arterial carbon dioxide partial pressure, patients sedated with isoflurane were twice as likely to breathe spontaneously than those se dated with propofol: adjusted risk ratio: 2.2 [95%CI: 1.4, 3.3], p < .001. Conclusions: Isoflurane compared to propofol sedation promotes early spontaneous breathing in deeply sedated ventilated intensive care patients. The benefit appears to be a direct effect isoflurane rather than being mediated by opioids or arterial carbon dioxide

MiR-277/4989 regulate transcriptional landscape during juvenile to adult transition in the parasitic helminth Schistosoma mansoni.

Schistosomes are parasitic helminths that cause schistosomiasis, a disease affecting circa 200 million people, primarily in underprivileged regions of the world. Schistosoma mansoni is the most experimentally tractable schistosome species due to its ease of propagation in the laboratory and the high quality of its genome assembly and annotation. Although there is growing interest in microRNAs (miRNAs) in trematodes, little is known about the role these molecules play in the context of developmental processes. We use the completely unaware "miRNA-blind" bioinformatics tool Sylamer to analyse the 3'-UTRs of transcripts differentially expressed between the juvenile and adult stages. We show that the miR-277/4989 family target sequence is the only one significantly enriched in the transition from juvenile to adult worms. Further, we describe a novel miRNA, sma-miR-4989 showing that its proximal genomic location to sma-miR-277 suggests that they form a miRNA cluster, and we propose hairpin folds for both miRNAs compatible with the miRNA pathway. In addition, we found that expression of sma-miR-277/4989 miRNAs are up-regulated in adults while their predicted targets are characterised by significant down-regulation in paired adult worms but remain largely undisturbed in immature "virgin" females. Finally, we show that sma-miR-4989 is expressed in tegumental cells located proximal to the oesophagus gland and also distributed throughout the male worms' body. Our results indicate that sma-miR-277/4989 might play a dominant role in post-transcriptional regulation during development of juvenile worms and suggest an important role in the sexual development of female schistosomes

Gene Expression Atlas of Schistosoma Mansoni - Part I

This data set (part I of two) was obtained from the RNA-Seq analysis of transcriptomes of adult <i>Schistosoma mansoni </i>and their gonads. All genes represented by transcripts identified in the analysis were given by their Smp numbers. In addition to the average transcript amounts (Reads per Kilobase Million (RPKM), Y-axis) and occurrence, log₂ ratios were given as well as adjusted <i>P</i> values of pairing-, gender,- and tissue-related expression patterns.Custom codes to generate the data are given in a separate file. <br>Abbreviations used for the bar plots (X-axis) are:<br>bM (bisex males), paired males; sM (single-sex males), unpaired males; bF (bisex females), paired females; sF (single-sex females), unpaired females; bT, testis of bM; sT, testis of sM; bO, ovary of bM; sO, ovary of sO. <br

Correction: MiR-277/4989 regulate transcriptional landscape during juvenile to adult transition in the parasitic helminth Schistosoma mansoni.

[This corrects the article DOI: 10.1371/journal.pntd.0005559.]

Sma-miR-277 and sma-miR-4989 belong to a gene cluster.

<p>(A) The genomic locus in Chromosome 4 of sma-miR-277 and sma-miR-4989 suggests they belong to a gene cluster. The average distance between genes (represented by coloured boxes) is 109 bases. Here the mature miRNAs (sma-miR2-277 and sma-miR-4989) and passenger miRNAs are represented with coverage plot and aligned reads from one of the small RNA libraries. (B) Predicted stem-loop structures for sma-miR-277 and sma-miR-4989 –individual cases. Mature miRNAs are located in the 3’-end of the hairpin. (C) Due to the cluster organisation of sma-miR-277/sma-miR-4989, it is likely that they are transcribed as one precursor RNA molecule. This figure represents the predicted stem-loop structure for sma-miR-277/sma-miR-4989 when arising from a larger transcript.</p

Sma-miR-277 family predicted targets downregulated in developing female parasites.

<p>Fold change expression (Log₂) of high confidence targets of sma-miR-277 family during the development of male and female worms in two conditions: paired (solid line red) and unpaired (dashed green). Black lines represent the mean expression of genes in paired (solid black line) and unpaired (dashed black line) worms.</p

High confidence targets of the sma-miR-277 family identified with a combined approach (Sylamer, miRanda and TargetScan with conservation).

<p>F = female; M = male.</p