Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR18645400_1.fastq.gz | Fastqsanger.gz | |||
| SRR18645400_2.fastq.gz | Fastqsanger.gz | |||
| SRR18645500_1.fastq.gz | Fastqsanger.gz | |||
| SRR18645500_2.fastq.gz | Fastqsanger.gz | |||
| SRR18645600_1.fastq.gz | Fastqsanger.gz |
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Project description:Small RNA pathways play diverse regulatory roles in the nematode C. elegans. However, our understanding of small RNA pathways, their conservation, and their roles in other nematodes is limited. Here, we analyzed small RNA pathways in the parasitic nematode Ascaris. Ascaris has ten Argonautes with five worm-specific Argonautes (WAGOs) that are associated with secondary 5’-triphosphate small RNAs (22-24G-RNAs). These Ascaris WAGOs and their small RNAs target repetitive sequences (WAGO-1, WAGO-2, WAGO-3, and NRDE-3) or mature mRNAs (CSR-1, NRDE-3, and WAGO-3) and are similar to the C. elegans mutator, nuclear, and CSR-1 small RNA pathways. Ascaris CSR-1 likely functions to “license” gene expression in the absence of an Ascaris piRNA pathway. Ascaris ALG-4 and its associated 26G-RNAs target and appear to repress specific mRNAs during meiosis in the testes. Notably, Ascaris WAGOs (WAGO-3 and NRDE-3) small RNAs change their targets between repetitive sequences and mRNAs during spermatogenesis or in early embryos illustrating target plasticity of these WAGOs. We provide a unique and comprehensive view of mRNA and small RNA expression throughout nematode spermatogenesis that illustrates the dynamics and flexibility of small RNA pathways. Overall, our study provides key insights into the conservation and divergence of nematode small RNA pathways.
2021-12-15 | GSE189061 | GEO
Project description:Ascariasis (roundworm) is the most prevalent parasitic nematode infection worldwide, impacting approximately 500 million people predominantly in low- and middle-income countries (LMICs). While people of all ages are infected with Ascaris, infection intensity (defined by worm burden) paradoxically peaks in pre-school and school aged children but then declines with age. The cause of age-dependent Ascaris worm intensity is not well understood but may be dependent on cellular changes in mucosal barrier sites. We have previously found that the gastric mucosa is a critical barrier site for Ascaris infection. Following oral ingestion of Ascaris eggs, larvae use AMCase secreted by gastric chief cells and acid secreted by gastric parietal cells to hatch. Once hatched, larvae translocate across the gastric mucosa to initiate the larval migratory cycle. However, inducing mucosal injury with administration of Tamoxifen induces mucosa cellular changes that impairs Ascaris hatching and reduces larval translocation across the gastric mucosa. In this study we established a repeated Ascaris suum challenge mouse model and evaluated if repeated Ascaris challenge also lead to cellular changes in the gastric mucosal barrier. We found that repeated Ascaris challenge caused cellular changes in the gastric mucosa which reduced worm intensity in the liver independent of the adaptive immune response. Thus, in endemic regions, where individuals experience recurrent infection throughout their lives, gastric cellular changes may be a key mechanism leading to the observed age-dependent Ascaris worm intensity changes from childhood to adulthood.
2025-03-03 | GSE290985 | GEO
Project description:Eukaryotic cells express several classes of small RNAs that regulate gene expression and ensure genome maintenance. Endogenous siRNAs (endo-siRNAs) and Piwi-interacting RNAs (piRNAs) mainly control gene and transposon expression in the germline, while microRNAs (miRNAs) generally function in post-transcriptional gene silencing in both somatic and germline cells. To provide an evolutionary and developmental perspective on small RNA pathways in nematodes, we identified and characterized known and novel small RNA classes through gametogenesis and embryo development in the parasitic nematode Ascaris suum and compared them with known small RNAs of Caenorhabditis elegans. piRNAs, Piwi-clade Argonautes, and other proteins associated with the piRNA pathway have been lost in Ascaris. miRNAs are synthesized immediately following fertilization in utero, prior to pronuclear fusion, and before the first cleavage of the zygote. This is the earliest expression of small RNAs ever described at a developmental stage long thought to be transcriptionally quiescent. A comparison of the two classes of Ascaris endo-siRNAs, 22G-RNAs and 26G-RNAs, to those in C. elegans, suggests great diversification and plasticity in the use of small RNA pathways during spermatogenesis in different nematodes. Our data reveal conserved characteristics of nematode small RNAs as well as features unique to Ascaris that illustrate significant flexibility in the use of small RNAs pathways, some of which are likely an adaptation to Ascaris’ life cycle and parasitism.
2011-06-16 | GSE26955 | GEO
Project description:Programmed DNA elimination is a developmentally regulated process leading to the reproducible loss of specific genomic sequences. DNA elimination occurs in unicellular ciliates and a variety of metazoans, including invertebrates and vertebrates. In metazoa, DNA elimination typically occurs in somatic cells during early development, leaving the germline genome intact. Reference genomes for metazoa that undergo DNA elimination are not available. Here, we generated germline and somatic reference genome sequences of the DNA eliminating pig parasitic nematode Ascaris suum and the horse parasite Parascaris univalens. In addition, we carried out in-depth analyses of DNA elimination in the parasitic nematode of humans, Ascaris lumbricoides, and the parasitic nematode of dogs, Toxocara canis. Our analysis of nematode DNA elimination reveals that in all species, repetitive sequences (that differ among the genera) and germline-expressed genes (approximately 1000-2000 or 5%-10% of the genes) are eliminated. Thirty-five percent of these eliminated genes are conserved among these nematodes, defining a core set of eliminated genes that are preferentially expressed during spermatogenesis. Our analysis supports the view that DNA elimination in nematodes silences germline-expressed genes. Over half of the chromosome break sites are conserved between Ascaris and Parascaris, whereas only 10% are conserved in the more divergent T. canis. Analysis of the chromosomal breakage regions suggests a sequence-independent mechanism for DNA breakage followed by telomere healing, with the formation of more accessible chromatin in the break regions prior to DNA elimination. Our genome assemblies and annotations also provide comprehensive resources for analysis of DNA elimination, parasitology research, and comparative nematode genome and epigenome studies.
2017-08-15 | GSE99523 | GEO
Project description:Programmed DNA elimination is a developmentally regulated process leading to the reproducible loss of specific genomic sequences. DNA elimination occurs in unicellular ciliates and a variety of metazoans, including invertebrates and vertebrates. In metazoa, DNA elimination typically occurs in somatic cells during early development, leaving the germline genome intact. Reference genomes for metazoa that undergo DNA elimination are not available. Here, we generated germline and somatic reference genome sequences of the DNA eliminating pig parasitic nematode Ascaris suum and the horse parasite Parascaris univalens. In addition, we carried out in-depth analyses of DNA elimination in the parasitic nematode of humans, Ascaris lumbricoides, and the parasitic nematode of dogs, Toxocara canis. Our analysis of nematode DNA elimination reveals that in all species, repetitive sequences (that differ among the genera) and germline-expressed genes (approximately 1000-2000 or 5%-10% of the genes) are eliminated. Thirty-five percent of these eliminated genes are conserved among these nematodes, defining a core set of eliminated genes that are preferentially expressed during spermatogenesis. Our analysis supports the view that DNA elimination in nematodes silences germline-expressed genes. Over half of the chromosome break sites are conserved between Ascaris and Parascaris, whereas only 10% are conserved in the more divergent T. canis. Analysis of the chromosomal breakage regions suggests a sequence-independent mechanism for DNA breakage followed by telomere healing, with the formation of more accessible chromatin in the break regions prior to DNA elimination. Our genome assemblies and annotations also provide comprehensive resources for analysis of DNA elimination, parasitology research, and comparative nematode genome and epigenome studies.
2017-08-15 | GSE99524 | GEO
Project description:In 2010, Ascaris caused 819 million infections worldwide. The impact on children is particularly severe, causing growth retardation and detrimental effects on cognitive development. Transmission is linked to unhygienic defecation habits, making ascariasis a disease of poverty. The WHO recognises it as one of the world's 17 neglected tropical diseases. Ascariasis is also an important parasite of pigs with economic implications including liver condemnation. Intriguingly some people (and pigs) are very heavily infected with Ascaris whereas others are not and this research aims to understand the factors that give rise to this difference and ultimately resistance to Ascaris itself. In our study we performed label free quantitative proteomics on livers of day four post infection C57BL/6J and CBA/Ca mice with and without Ascaris infection to identify proteins changes potentially linked to both resistance and susceptibility amongst the two strains, respectively. In addition tio major intrinsic differences between the two strains signatures of a differential immune response and direct modulation of host processes by the nematode were resolved.
2016-08-08 | PXD003555 | Pride
Project description:Organisms invest significant effort into maintaining genome stability. However, in diverse groups of eukaryotes, portions or entire chromosomes are lost in early development or during sex determination, a process known as programmed DNA elimination. Little is known about how different segments of the genome are reproducibly retained and discarded during programmed DNA elimination. We tested the hypothesis that selective retention is mediated by regulation of centromere-mediated association of chromosome segments with the mitotic spindle. We report that on the holocentric chromosomes of the nematode Ascaris, the core centromeric histone CENP-A is localized differently in cells undergoing DNA elimination from those undergoing germline mitosis. Prior to DNA elimination, CENP-A is significantly reduced in chromosome regions that will be lost. CENP-A reduction in eliminated genomic regions leads to the absence of kinetochores and microtubule attachment sites necessary for chromosome segregation, and thus the loss of these DNA regions during Ascaris programmed DNA elimination. Our results show that holocentric chromosome organization in Ascaris is regulated and that changes in CENP-A deposition specify which portions of chromosomes will be eliminated during programmed DNA elimination. A total of 62 samples are analyzed. These include: (1). CENP-A ChIP-seq on 12 developmental stages with input and replicates (12 x 2 x 2 samples); (2). CENP-C ChIP-seq on 3 developmental stages with input and replicates (total 8 samples); and (3). Histone marks ChIP-seq with 6 samples
2016-07-15 | E-GEOD-76914 | biostudies-arrayexpress