Genetics: modes of reproduction and genetic analysis

Streit, Adrian

doi:10.1017/s0031182016000342

Cited by 20 publications

(19 citation statements)

References 107 publications

(192 reference statements)

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“…Life Cycle Strongyloides spp. have unique and complex life cycles that alternate between parasitic and free-living generations [29]. The host is infected when iL3 penetrate the host skin, migrate through the host body, and finally establish themselves in the mucosa of small intestine.…”

Section: Basic Biologymentioning

confidence: 99%

“…and P. trichosuri follow XX/XO sex determination mechanisms suggesting that XX/XO sex determination is ancestral in the family Strongyloididae [39]. In Strongyloides spp., meiotic recombination only occurs in the free-living generations because females of the parasitic generation reproduce by mitotic parthenogenesis [29]. Due to the presence of an extra X chromosome, parasitic females are capable of producing male and female offspring parthenogenetically.…”

Section: Basic Biologymentioning

confidence: 99%

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Advances in the Molecular and Cellular Biology of Strongyloides spp.

Jaleta

Lok

2019

Curr Trop Med Rep

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Purpose of Review This paper constitutes an update of recent studies on the general biology, molecular genetics, and cellular biology of Strongyloides spp. and related parasitic nematodes. Recent Findings Increasingly, human strongyloidiasis is considered the most neglected of neglected tropical diseases. Despite this, the last 5 years has seen remarkable advances in the molecular biology of Strongyloides spp. Genome sequences for S. stercoralis, S. ratti, S. venezuelensis, S. papillosus, and the related parasite Parastrongyloides trichosuri were created, annotated, and analyzed. These genomic resources, along with a practical transgenesis platform for Strongyloides spp., aided a major achievement, the advent of targeted mutagenesis via CRISPR/Cas9 in S. stercoralis and S. ratti. The genome sequences have also enabled significant molecular epidemiologic and phylogenetic findings on human strongyloidiasis, including the first genetic evidence of zoonotic transmission of S. stercoralis between dogs and humans. Studies of molecular signaling pathways identified the nuclear receptor Ss-DAF-12 as one that can be manipulated in the parasite by exogenous application of its steroid ligands. The chemotherapeutic implications of this were unscored by a study in which a Ss-DAF-12 ligand suppressed autoinfection by S. stercoralis in a new murine model of human strongyloidiasis. Summary Seminal advances in genomics of Strongyloides spp. have transformed research into strongyloidiasis, facilitating fundamental phylogenetic and epidemiologic studies and aiding the deployment of CRISPR/Cas9 gene disruption and editing as functional genomic tools in Strongyloides spp. Studies of Ss-DAF-12 signaling in S. stercoralis demonstrated the potential of this pathway as a novel chemotherapeutic target in parasitic nematodes.

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Section: Basic Biologymentioning

confidence: 99%

Section: Basic Biologymentioning

confidence: 99%

Advances in the Molecular and Cellular Biology of Strongyloides spp.

Jaleta

Lok

2019

Curr Trop Med Rep

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“…2005). S. papillosus has a unique and complex life cycle that consist of parasitic and free-living generations (Streit 2017; Viney and Lok 2015). The adult parasites are only females and live in the mucosa of the small intestine where they lay embryonated eggs that pass with host feces.…”

Section: Introductionmentioning

confidence: 99%

“…The life cycle of S. papillosus is illustrated in figure 1 A . The alternating life cycles between free-living and parasitic generations provide a unique opportunity to apply available genetic and molecular tools for a better understanding of the basic biology and evolution of parasitism in Strongyloides (Streit 2017). Hunt et al.…”

Section: Introductionmentioning

confidence: 99%

Duplications and Positive Selection Drive the Evolution of Parasitism-Associated Gene Families in the Nematode Strongyloides papillosus

Baskaran

Jaleta

Streit

et al. 2017

Genome Biology and Evolution

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Gene duplication is a major mechanism playing a role in the evolution of phenotypic complexity and in the generation of novel traits. By comparing parasitic and nonparasitic nematodes, a recent study found that the evolution of parasitism in Strongyloididae is associated with a large expansion in the Astacin and CAP gene families.To gain novel insights into the developmental processes in the sheep parasite Strongyloides papillosus, we sequenced transcriptomes of different developmental stages and sexes. Overall, we found that the majority of genes are developmentally regulated and have one-to-one orthologs in the diverged S. ratti genome. Together with the finding of similar expression profiles between S. papillosus and S. ratti, these results indicate a strong evolutionary constraint acting against change at sequence and expression levels. However, the comparison between parasitic and free-living females demonstrates a quite divergent pattern that is mostly due to the previously mentioned expansion in the Astacin and CAP gene families. More detailed phylogenetic analysis of both gene families shows that most members date back to single expansion events early in the Strongyloides lineage and have undergone subfunctionalization resulting in clusters that are highly expressed either in infective larvae or in parasitic females. Finally, we found increased evidence for positive selection in both gene families relative to the genome-wide expectation.In summary, our study reveals first insights into the developmental transcriptomes of S. papillosus and provides a detailed analysis of sequence and expression evolution in parasitism-associated gene families.

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“…The genetics of the Strongyloides life cycle have also been of enduring interest – and confusion – to researchers, and the current, sophisticated understanding of Strongyloides ’ genetics is reviewed here by Adrian Streit (Streit, 2016). The most detailed genetic analyses have been for S. ratti and Strongyloides papillosus , which also highlights the interesting species-specific differences, since these species represent two sub-clades within the genus.…”

mentioning

confidence: 99%

Strongyloides

Viney

2016

Parasitology

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Genetics: modes of reproduction and genetic analysis

Cited by 20 publications

References 107 publications

Advances in the Molecular and Cellular Biology of Strongyloides spp.

Advances in the Molecular and Cellular Biology of Strongyloides spp.

Duplications and Positive Selection Drive the Evolution of Parasitism-Associated Gene Families in the Nematode Strongyloides papillosus

Strongyloides

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