Shawn Ahmed
YOU?
Author Swipe
View article: Piwi mutant germ cells transmit a form of heritable stress that promotes longevity
Piwi mutant germ cells transmit a form of heritable stress that promotes longevity Open
The C. elegans Argonaute protein PRG-1/Piwi and associated piRNAs protect metazoan genomes by silencing transposons and other types of foreign DNA. As prg-1 mutants are propagated, their fertility deteriorates prior to the onset of a repro…
View article: Piwi mutant germ cells transmit a form of heritable stress that promotes longevity
Piwi mutant germ cells transmit a form of heritable stress that promotes longevity Open
The C . elegans Argonaute protein PRG‐1/Piwi and associated piRNAs protect metazoan genomes by silencing transposons and other types of foreign DNA. As prg‐1 mutants are propagated, their fertility deteriorates prior to the onset of a repr…
View article: RTEL-1 and DNA polymerase theta promote subtelomeric DNA synthesis and telomere fusion in <i>C. elegans</i>
RTEL-1 and DNA polymerase theta promote subtelomeric DNA synthesis and telomere fusion in <i>C. elegans</i> Open
Interstitial telomere sequences (ITS) are degenerate telomere tracts scattered along chromosome arms whose functions are not well understood. We found that critically shortened telomeres of C. elegans telomerase mutants initiate DNA synthe…
View article: Nematode chromosomes
Nematode chromosomes Open
The nematode Caenorhabditis elegans has shed light on many aspects of eukaryotic biology, including genetics, development, cell biology, and genomics. A major factor in the success of C. elegans as a model organism has been the availabilit…
View article: Genetic and Epigenetic Inheritance at Telomeres
Genetic and Epigenetic Inheritance at Telomeres Open
Transgenerational inheritance can occur at telomeres in distinct contexts. Deficiency for telomerase or telomere-binding proteins in germ cells can result in shortened or lengthened chromosome termini that are transmitted to progeny. In hu…
View article: Checkpoints: Chromosome pairing takes an unexpected twist
Checkpoints: Chromosome pairing takes an unexpected twist Open
When meiotic cells complete S phase, homologous chromosomes pair, synapse and undergo recombination. A checkpoint protein is somehow required for meiotic chromosome pairing in C. elegans, thus providing a direct link between S phase and th…
View article: Engineering threshold-based selection systems
Engineering threshold-based selection systems Open
Using model organisms to identify novel therapeutic targets is frequently constrained by pre-existing genetic toolkits. To expedite positive selection for identification of novel downstream effectors, we engineered conditional expression o…
View article: Uncoupling of pathways that promote postmitotic life span and apoptosis from replicative immortality of Caenorhabditis elegans germ cells
Uncoupling of pathways that promote postmitotic life span and apoptosis from replicative immortality of Caenorhabditis elegans germ cells Open
A dichotomy exists between germ and somatic cells in most organisms, such that somatic cell lineages proliferate for a single generation, whereas the germ cell lineage has the capacity to proliferate from one generation to the next, indefi…
View article: Germ granule dysfunction is a hallmark and mirror of Piwi mutant sterility
Germ granule dysfunction is a hallmark and mirror of Piwi mutant sterility Open
In several species, Piwi/piRNA genome silencing defects cause immediate sterility that correlates with transposon expression and transposon-induced genomic instability. In C. elegans , mutations in the Piwi-related gene ( prg-1 ) and other…
View article: Engineering Threshold-Based Selection Systems
Engineering Threshold-Based Selection Systems Open
Using model organisms to identify novel therapeutic targets is frequently constrained by pre-existing genetic toolkits. To expedite positive selection for identification of novel downstream effectors, we engineered conditional expression o…
View article: Gametes deficient for Pot1 telomere binding proteins alter levels of telomeric foci for multiple generations
Gametes deficient for Pot1 telomere binding proteins alter levels of telomeric foci for multiple generations Open
Deficiency for telomerase results in transgenerational shortening of telomeres. However, telomeres have no known role in transgenerational epigenetic inheritance. C. elegans Protection Of Telomeres 1 (Pot1) proteins form foci at the telome…
View article: The MRT-1 nuclease is required for DNA crosslink repair and telomerase activity in vivo in Caenorhabditis elegans
The MRT-1 nuclease is required for DNA crosslink repair and telomerase activity in vivo in Caenorhabditis elegans Open
The telomerase reverse transcriptase adds de novo DNA repeats to chromosome termini. Here we define Caenorhabditis elegans MRT-1 as a novel factor required for telomerase-mediated telomere replication and the DNA-damage response. MRT-1 is …
View article: Lack of pairing during meiosis triggers multigenerational transgene silencing in Caenorhabditis elegans
Lack of pairing during meiosis triggers multigenerational transgene silencing in Caenorhabditis elegans Open
Transgenes can be permanently silenced in a single generation via a previously described small RNA-induced epigenetic silencing (RNAe) mechanism, which is promoted by the presence of a perfect Piwi-interacting RNA (piRNA) target site. In t…
View article: trt-1 Is the Caenorhabditis elegans Catalytic Subunit of Telomerase
trt-1 Is the Caenorhabditis elegans Catalytic Subunit of Telomerase Open
Mutants of trt-1, the Caenorhabditis elegans telomerase reverse transcriptase, reproduce normally for several generations but eventually become sterile as a consequence of telomere erosion and end-to-end chromosome fusions. Telomere erosio…
View article: In Vivo Analysis of Conserved C. elegans Tomosyn Domains
In Vivo Analysis of Conserved C. elegans Tomosyn Domains Open
Neurosecretion is critically dependent on the assembly of a macromolecular complex between the SNARE proteins syntaxin, SNAP-25 and synaptobrevin. Evidence indicates that the binding of tomosyn to syntaxin and SNAP-25 interferes with this …
View article: The Caenorhabditis elegans Homolog of Gen1/Yen1 Resolvases Links DNA Damage Signaling to DNA Double-Strand Break Repair
The Caenorhabditis elegans Homolog of Gen1/Yen1 Resolvases Links DNA Damage Signaling to DNA Double-Strand Break Repair Open
DNA double-strand breaks (DSBs) can be repaired by homologous recombination (HR), which can involve Holliday junction (HJ) intermediates that are ultimately resolved by nucleolytic enzymes. An N-terminal fragment of human GEN1 has recently…
View article: Telomere dysfunction in human bone marrow failure syndromes
Telomere dysfunction in human bone marrow failure syndromes Open
Approximately 90% of all human cancers, in which some deregulation of cell cycle arrest or programmed cell death has occurred, express telomerase, a ribonucleoprotein whose activity is normally turned off in healthy somatic tissues. Additi…
View article: Caenorhabditis elegans POT-1 and POT-2 Repress Telomere Maintenance Pathways
Caenorhabditis elegans POT-1 and POT-2 Repress Telomere Maintenance Pathways Open
Telomeres are composed of simple tandem DNA repeats that protect the ends of linear chromosomes from replicative erosion or inappropriate DNA damage response mechanisms. The mammalian Protection Of Telomeres (POT1) protein interacts with s…
View article: The Caenorhabditis elegans Rad17 Homolog HPR-17 Is Required for Telomere Replication
The Caenorhabditis elegans Rad17 Homolog HPR-17 Is Required for Telomere Replication Open
Subunits of the Rad9/Rad1/Hus1 (9-1-1) proliferating cell nuclear antigen (PNCA)-like sliding clamp are required for DNA damage responses and telomerase-mediated telomere replication in the nematode Caenorhabditis elegans. PCNA sliding cla…
View article: Reduced Insulin/IGF-1 Signaling Restores Germ Cell Immortality to Caenorhabditis elegans Piwi Mutants
Reduced Insulin/IGF-1 Signaling Restores Germ Cell Immortality to Caenorhabditis elegans Piwi Mutants Open
Defects in the Piwi/piRNA pathway lead to transposon desilencing and immediate sterility in many organisms. We found that the C. elegans Piwi mutant prg-1 became sterile after growth for many generations. This phenotype did not occur for R…
View article: piRNAs Can Trigger a Multigenerational Epigenetic Memory in the Germline of C. elegans
piRNAs Can Trigger a Multigenerational Epigenetic Memory in the Germline of C. elegans Open
SummaryTransgenerational effects have wide-ranging implications for human health, biological adaptation, and evolution; however, their mechanisms and biology remain poorly understood. Here, we demonstrate that a germline nuclear small RNA/…
View article: H3K4 demethylase activities repress proliferative and postmitotic aging
H3K4 demethylase activities repress proliferative and postmitotic aging Open
Homeostasis of postmitotic and proliferating cells is maintained by pathways that repress stress. We found that the Caenorhabditis elegans histone 3 lysine 4 (H3K4) demethylases RBR-2 and SPR-5 promoted postmitotic longevity of stress-resi…
View article: Corrigendum: Telomeric small RNAs in the genus <i>Caenorhabditis</i>
Corrigendum: Telomeric small RNAs in the genus <i>Caenorhabditis</i> Open
View article: Maternal Inheritance: Longevity Programs Nourish Progeny via Yolk
Maternal Inheritance: Longevity Programs Nourish Progeny via Yolk Open
View article: POT-1 telomere binding protein promotes a novel form of Transgenerational Epigenetic Inheritance
POT-1 telomere binding protein promotes a novel form of Transgenerational Epigenetic Inheritance Open
Summary Transgenerational Epigenetic Inheritance occurs when gametes transmit forms of information without altering genomic DNA 1 . Although deficiency for telomerase in human families causes transgenerational shortening of telomeres 2 , a…
View article: Telomeric small RNAs in the genus <i>Caenorhabditis</i>
Telomeric small RNAs in the genus <i>Caenorhabditis</i> Open
Telomeric DNA is composed of simple tandem repeat sequences and has a G-rich strand that runs 5′ to 3′ toward the chromosome terminus. Small RNAs with homology to telomeres have been observed in several organisms and could originate from t…
View article: Telomeric small RNAs in the genus <i>Caenorhabditis</i>
Telomeric small RNAs in the genus <i>Caenorhabditis</i> Open
Telomeric DNA is composed of simple tandem repeat sequences and has a G-rich strand that runs 5’ to 3’ towards the chromosome terminus. Small RNAs with homology to telomeres have been observed in several organisms and could originate from …
View article: The meiotic phosphatase GSP-2/PP1 promotes germline immortality and small RNA-mediated genome silencing
The meiotic phosphatase GSP-2/PP1 promotes germline immortality and small RNA-mediated genome silencing Open
Germ cell immortality, or transgenerational maintenance of the germ line, could be promoted by mechanisms that could occur in either mitotic or meiotic germ cells. Here we report for the first time that the GSP-2 PP1/Glc7 phosphatase promo…
View article: DAF-16/Foxo suppresses the transgenerational sterility of <i>prg-1</i> piRNA mutants via a systemic small RNA pathway
DAF-16/Foxo suppresses the transgenerational sterility of <i>prg-1</i> piRNA mutants via a systemic small RNA pathway Open
Mutation of the daf-2 insulin/IGF-1 receptor activates the DAF-16/Foxo transcription factor to suppress the transgenerational sterility phenotype of prg-1 /piRNA mutants that are deficient for piRNA-mediated genome silencing. As with PRG-1…
View article: Piwi mutant germ cells transmit a form of heritable stress that promotes longevity
Piwi mutant germ cells transmit a form of heritable stress that promotes longevity Open
Summary The C. elegans Argonaute protein PRG-1/Piwi and associated piRNAs protect metazoan genomes by silencing transposons and other types of foreign DNA. As prg-1 mutants are propagated, their fertility deteriorates prior to the onset of…