The nematode Oscheius tipulae as a genetic model for programmed DNA elimination

Dockendorff, Thomas C.; Estrem, Brandon; Reed, Jordan; Simmons, James R.; Zadegan, Sobhan Bahrami; Zagoskin, Maxim V.; Terta, Vincent; Villalobos, E. Sanz de; Seaberry, Erin M.; Wang, Jianbin

doi:10.1016/j.cub.2022.10.043

Cited by 14 publications

(45 citation statements)

References 97 publications

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“…The recent identification of PDE in free-living nematode species prompts questions about how frequently PDE occurs among metazoans (especially nematodes) and the selective advantage(s) it may provide. Free-living nematodes with PDE also present new opportunities to study PDE in genetically tractable systems [ 56 ]. These studies will complement work in Ascaris and provide comparative and evolutionary perspectives on PDE in metazoans.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, PDE in several other systems occurs in many cells at a single embryo division, such as the free-living nematode O . tipulae (fourth division) [ 56 ], the copepod Mesocyclops edax (fifth division), and the sea lamprey Petromyzon marinus (sixth division) [ 49 ]. It is unclear why organisms undergo PDE at different stages of embryogenesis and whether the timing of PDE is strictly associated with the transition from germline to somatic cells.…”

Section: Introductionmentioning

confidence: 99%

“…This end resection is also conserved in O . tipulae PDE [ 56 ]. In addition, the timing of initial breaks detected by END-seq suggests Ascaris chromosomes are broken prior to the onset of mitosis, consistent with EM observations [ 41 ].…”

Section: Introductionmentioning

confidence: 99%

“…The presence of PDE in phylogenetically diverse organisms suggests PDE may provide some selective advantage [ 43 , 45 , 49 ]. One consequence of PDE is the permanent removal of specific repetitive elements in all somatic cells, a common feature among all known species that undergo PDE [ 40 , 55 , 56 ]. In Ascaris , 54% of the eliminated DNA consists of 121 bp tandem repeats.…”

Section: Introductionmentioning

confidence: 99%

“…A recent study in the free-living nematode O . tipulae demonstrated a fail-safe mechanism is in place to ensure the removal of chromosome ends during PDE [ 56 ], emphasizing the importance of end removal for the biology of these species. Future studies are warranted to determine the functions of the eliminated DNA in the germline and the benefit of its removal in the somatic cells.…”

Section: Introductionmentioning

confidence: 99%

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Programmed DNA elimination in the parasitic nematode Ascaris

Estrem

Wang

2023

PLoS Pathog

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In most organisms, the whole genome is maintained throughout the life span. However, exceptions occur in some species where the genome is reduced during development through a process known as programmed DNA elimination (PDE). In the human and pig parasite Ascaris, PDE occurs during the 4 to 16 cell stages of embryogenesis, when germline chromosomes are fragmented and specific DNA sequences are reproducibly lost in all somatic cells. PDE was identified in Ascaris over 120 years ago, but little was known about its molecular details until recently. Genome sequencing revealed that approximately 1,000 germline-expressed genes are eliminated in Ascaris, suggesting PDE is a gene silencing mechanism. All germline chromosome ends are removed and remodeled during PDE. In addition, PDE increases the number of chromosomes in the somatic genome by splitting many germline chromosomes. Comparative genomics indicates that these germline chromosomes arose from fusion events. PDE separates these chromosomes at the fusion sites. These observations indicate that PDE plays a role in chromosome karyotype and evolution. Furthermore, comparative analysis of PDE in other parasitic and free-living nematodes illustrates conserved features of PDE, suggesting it has important biological significance. We summarize what is known about PDE in Ascaris and its relatives. We also discuss other potential functions, mechanisms, and the evolution of PDE in these parasites of humans and animals of veterinary importance.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%