1
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Chen S, Phillips CM. HRDE-2 drives small RNA specificity for the nuclear Argonaute protein HRDE-1. Nat Commun 2024; 15:957. [PMID: 38302462 PMCID: PMC10834429 DOI: 10.1038/s41467-024-45245-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 01/18/2024] [Indexed: 02/03/2024] Open
Abstract
RNA interference (RNAi) is a conserved gene silencing process that exists in diverse organisms to protect genome integrity and regulate gene expression. In C. elegans, the majority of RNAi pathway proteins localize to perinuclear, phase-separated germ granules, which are comprised of sub-domains referred to as P granules, Mutator foci, Z granules, and SIMR foci. However, the protein components and function of the newly discovered SIMR foci are unknown. Here we demonstrate that HRDE-2 localizes to SIMR foci and interacts with the germline nuclear Argonaute HRDE-1 in its small RNA unbound state. In the absence of HRDE-2, HRDE-1 exclusively loads CSR-class 22G-RNAs rather than WAGO-class 22G-RNAs, resulting in inappropriate H3K9me3 deposition on CSR-target genes. Thus, our study demonstrates that the recruitment of unloaded HRDE-1 to germ granules, mediated by HRDE-2, is critical to ensure that the correct small RNAs are used to guide nuclear RNA silencing in the C. elegans germline.
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Affiliation(s)
- Shihui Chen
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA.
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2
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Uebel CJ, Rajeev S, Phillips CM. Caenorhabditis elegans germ granules are present in distinct configurations and assemble in a hierarchical manner. Development 2023; 150:dev202284. [PMID: 38009921 PMCID: PMC10753583 DOI: 10.1242/dev.202284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/17/2023] [Indexed: 11/29/2023]
Abstract
RNA silencing pathways are complex, highly conserved, and perform crucial regulatory roles. In Caenorhabditis elegans germlines, RNA surveillance occurs through a series of perinuclear germ granule compartments - P granules, Z granules, SIMR foci, and Mutator foci - multiple of which form via phase separation. Although the functions of individual germ granule proteins have been extensively studied, the relationships between germ granule compartments (collectively, 'nuage') are less understood. We find that key germ granule proteins assemble into separate but adjacent condensates, and that boundaries between germ granule compartments re-establish after perturbation. We discover a toroidal P granule morphology, which encircles the other germ granule compartments in a consistent exterior-to-interior spatial organization, providing broad implications for the trajectory of an RNA as it exits the nucleus. Moreover, we quantify the stoichiometric relationships between germ granule compartments and RNA to reveal discrete populations of nuage that assemble in a hierarchical manner and differentially associate with RNAi-targeted transcripts, possibly suggesting functional differences between nuage configurations. Our work creates a more accurate model of C. elegans nuage and informs the conceptualization of RNA silencing through the germ granule compartments.
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Affiliation(s)
- Celja J. Uebel
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Sanjana Rajeev
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Carolyn M. Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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3
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Uebel CJ, Rajeev S, Phillips CM. Caenorhabditis elegans germ granules are present in distinct configurations that differentially associate with RNAi-targeted RNAs. bioRxiv 2023:2023.05.25.542330. [PMID: 37292702 PMCID: PMC10246010 DOI: 10.1101/2023.05.25.542330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
RNA silencing pathways are complex, highly conserved, and perform widespread, critical regulatory roles. In C. elegans germlines, RNA surveillance occurs through a series of perinuclear germ granule compartments-P granules, Z granules, SIMR foci, and Mutator foci-multiple of which form via phase separation and exhibit liquid-like properties. The functions of individual proteins within germ granules are well-studied, but the spatial organization, physical interaction, and coordination of biomolecule exchange between compartments within germ granule "nuage" is less understood. Here we find that key proteins are sufficient for compartment separation, and that the boundary between compartments can be reestablished after perturbation. Using super-resolution microscopy, we discover a toroidal P granule morphology which encircles the other germ granule compartments in a consistent exterior-to-interior spatial organization. Combined with findings that nuclear pores primarily interact with P granules, this nuage compartment organization has broad implications for the trajectory of an RNA as it exits the nucleus and enters small RNA pathway compartments. Furthermore, we quantify the stoichiometric relationships between germ granule compartments and RNA to reveal discrete populations of nuage that differentially associate with RNAi-targeted transcripts, possibly suggesting functional differences between nuage configurations. Together, our work creates a more spatially and compositionally accurate model of C. elegans nuage which informs the conceptualization of RNA silencing through different germ granule compartments.
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Affiliation(s)
- Celja J. Uebel
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
- Present address: Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford CA, 94305
| | - Sanjana Rajeev
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
| | - Carolyn M. Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
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4
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Phillips CM, Updike DL. Germ granules and gene regulation in the Caenorhabditis elegans germline. Genetics 2022; 220:6541922. [PMID: 35239965 PMCID: PMC8893257 DOI: 10.1093/genetics/iyab195] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 10/10/2021] [Indexed: 01/27/2023] Open
Abstract
The transparency of Caenorhabditis elegans provides a unique window to observe and study the function of germ granules. Germ granules are specialized ribonucleoprotein (RNP) assemblies specific to the germline cytoplasm, and they are largely conserved across Metazoa. Within the germline cytoplasm, they are positioned to regulate mRNA abundance, translation, small RNA production, and cytoplasmic inheritance to help specify and maintain germline identity across generations. Here we provide an overview of germ granules and focus on the significance of more recent observations that describe how they further demix into sub-granules, each with unique compositions and functions.
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Affiliation(s)
- Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA,Corresponding author: (C.M.P.); (D.L.U.)
| | - Dustin L Updike
- The Mount Desert Island Biological Laboratory, Bar Harbor, ME 04672, USA,Corresponding author: (C.M.P.); (D.L.U.)
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5
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Lecorguillé M, Navarro P, Shivappa N, Hébert JR, Mehegan J, Kelleher CC, Suderman M, Phillips CM. Maternal and paternal dietary quality, dietary inflammation status, and offspring DNA methylation. Eur J Public Health 2021. [DOI: 10.1093/eurpub/ckab164.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Altered nutritional conditions at early life stages may increase the risk of future disease in offspring. Recent evidence suggests that developmental programming may involve epigenetic mechanisms. However, few studies have evaluated the effect of parental dietary quality on offspring DNA methylation. We investigated the relationships between dietary quality and inflammatory potential of future parents and DNA methylation of their children at nine years.
Methods
We used data from the Lifeways Cross-Generation cohort, established between 2001 and 2003 in the Republic of Ireland. Maternal dietary intake during the first trimester and paternal diet of the 12 previous months were assessed with a food-frequency questionnaire. Dietary quality and inflammation were determined by the healthy eating index (HEI) 2015 score and the energy-adjusted dietary inflammation index (E-DII), respectively. The Illumina Infinium HumanMethylationEPIC (EPIC array) assessed methylation levels in saliva samples from 264 children. Dietary associations with DNA methylation at individual CpG sites were examined.
Results
After adjusting for multiple tests, maternal HEI-2015 scores were inversely associated with DNA methylation at 1 CpG site (cg21840035, p-value=5.5 × 10-8) located near the PLEKHM1 gene, whose functions involve regulation of bone development. An increase in paternal HEI score was related to lower methylation at one CpG site (cg22431767, p-value=4.1× 10-8) located near cell signaling gene LUZP1. No significant associations between maternal or paternal E-DII and DNA methylation at individual CpG sites were observed.
Conclusions
Parental dietary quality in the prenatal period may influence offspring childhood DNA methylation. A better understanding of the nutritional programming effects on epigenetic markers is essential to design public health strategies that could help women to achieve a healthier diet and optimize the health capital of children and future generations.
Key messages
Our findings suggest that both maternal and paternal dietary quality may have a long-term influence on the offspring epigenome, expand the current understanding of parental nutritional programming. Replication in other populations with contrasted dietary intake is warranted, with a view to informing public health recommendations to benefit the health of future generations.
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Affiliation(s)
- M Lecorguillé
- School of Public Health, Physiotherapy, and Sports Science, University College Dublin, Dublin, Ireland
| | - P Navarro
- School of Public Health, Physiotherapy, and Sports Science, University College Dublin, Dublin, Ireland
| | - N Shivappa
- Cancer Prevention and Control Program, Arnold School of Public Health, University of South Carolina, Columbia, USA
| | - JR Hébert
- Cancer Prevention and Control Program, Arnold School of Public Health, University of South Carolina, Columbia, USA
- Connecting Health Innovations, LLC, Columbia, USA
| | - J Mehegan
- School of Public Health, Physiotherapy, and Sports Science, University College Dublin, Dublin, Ireland
| | - CC Kelleher
- School of Public Health, Physiotherapy, and Sports Science, University College Dublin, Dublin, Ireland
| | - M Suderman
- MRC Integrative Epidemiology Unit, Population Health Science, University of Bristol, Bristol, UK
| | - CM Phillips
- School of Public Health, Physiotherapy, and Sports Science, University College Dublin, Dublin, Ireland
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6
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Nguyen DAH, Phillips CM. Arginine methylation promotes siRNA-binding specificity for a spermatogenesis-specific isoform of the Argonaute protein CSR-1. Nat Commun 2021; 12:4212. [PMID: 34244496 PMCID: PMC8270938 DOI: 10.1038/s41467-021-24526-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 06/23/2021] [Indexed: 01/15/2023] Open
Abstract
CSR-1 is an essential Argonaute protein that binds to a subclass of 22G-RNAs targeting most germline-expressed genes. Here we show that the two isoforms of CSR-1 have distinct expression patterns; CSR-1B is ubiquitously expressed throughout the germline and during all stages of development while CSR-1A expression is restricted to germ cells undergoing spermatogenesis. Furthermore, CSR-1A associates preferentially with 22G-RNAs mapping to spermatogenesis-specific genes whereas CSR-1B-bound small RNAs map predominantly to oogenesis-specific genes. Interestingly, the exon unique to CSR-1A contains multiple dimethylarginine modifications, which are necessary for the preferential binding of CSR-1A to spermatogenesis-specific 22G-RNAs. Thus, we have discovered a regulatory mechanism for C. elegans Argonaute proteins that allows for specificity of small RNA binding between similar Argonaute proteins with overlapping temporal and spatial localization. The Argonaute protein CSR-1 is essential for fertility and viability in C. elegans. Here the authors show that CSR-1A isoform associates preferentially with small RNAs mapping to spermatogenesis-specific genes while CSR-1B isoform binds small RNAs mapping to oogenesis-specific genes. Arginine methylation of CSR-1A promotes small RNA-binding specificity.
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Affiliation(s)
- Dieu An H Nguyen
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.
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7
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Abstract
RNA interference is a widely conserved mechanism of gene regulation and silencing across eukaryotes. In C. elegans, RNA silencing is coordinated through perinuclear nuage containing at least four granules: P granules, Z granules, Mutator foci, and SIMR foci. Embryonic localization of these granules is known for all except SIMR foci. Here we establish that SIMR foci first appear at the nuclear periphery in the P4 germline blastomere and become numerous and bright in the Z2 and Z3 progenitor germ cells. This timing coincides with the appearance or de-mixing of other germline granules, providing further evidence for coordinated germ granule reorganization.
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Affiliation(s)
- Celja J Uebel
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Kevin I Manage
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
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8
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Zhong X, Powell C, Phillips CM, Millar SR, Carson BP, Dowd KP, Perry IJ, Kearney PM, Harrington JM, O'Toole PW, Donnelly AE. The Influence of Different Physical Activity Behaviours on the Gut Microbiota of Older Irish Adults. J Nutr Health Aging 2021; 25:854-861. [PMID: 34409962 DOI: 10.1007/s12603-021-1630-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE A 24-hour day is made up of time spent in a range of physical activity (PA) behaviours, including sleep, sedentary time, standing, light-intensity PA (LIPA) and moderate-to-vigorous PA (MVPA), all of which may have the potential to alter an individual's health through various different pathways and mechanisms. This study aimed to explore the relationship between PA behaviours and the gut microbiome in older adults. DESIGN Cross-sectional study. SETTINGS AND PARTICIPANTS Participants (n=100; age 69.0 [3.0] years; 44% female) from the Mitchelstown Cohort Rescreen (MCR) Study (2015-2017). METHODS Participants provided measures of gut microbiome composition (profiled by sequencing 16S rRNA gene amplicons), and objective measures of PA behaviours (by a 7-day wear protocol using an activPAL3 Micro). RESULTS Standing time was positively correlated with the abundance of butyrate-producing and anti-inflammatory bacteria, including Ruminococcaceae, Lachnospiraceae and Bifidobacterium, MVPA was positively associated with the abundance of Lachnospiraceae bacteria, while sedentary time was associated with lower abundance of Ruminococcaceae and higher abundance of Streptococcus spp. CONCLUSION Physical activity behaviours appear to influence gut microbiota composition in older adults, with different PA behaviours having diverging effects on gut microbiota composition.
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Affiliation(s)
- X Zhong
- Prof. Alan E. Donnelly, Department of Physical Education and Sport Sciences, University of Limerick, Limerick, Ireland, , Tel: +353 61 202808
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9
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Uebel CJ, Agbede D, Wallis DC, Phillips CM. Mutator Foci Are Regulated by Developmental Stage, RNA, and the Germline Cell Cycle in Caenorhabditis elegans. G3 (Bethesda) 2020; 10:3719-3728. [PMID: 32763952 PMCID: PMC7534428 DOI: 10.1534/g3.120.401514] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 08/03/2020] [Indexed: 02/02/2023]
Abstract
RNA interference is a crucial gene regulatory mechanism in Caenorhabditis elegans Phase-separated perinuclear germline compartments called Mutator foci are a key element of RNAi, ensuring robust gene silencing and transgenerational epigenetic inheritance. Despite their importance, Mutator foci regulation is not well understood, and observations of Mutator foci have been largely limited to adult hermaphrodite germlines. Here we reveal that punctate Mutator foci arise in the progenitor germ cells of early embryos and persist throughout all larval stages. They are additionally present throughout the male germline and in the cytoplasm of post-meiotic spermatids, suggestive of a role in paternal epigenetic inheritance. In the adult germline, transcriptional inhibition results in a pachytene-specific loss of Mutator foci, indicating that Mutator foci are partially reliant on RNA for their stability. Finally, we demonstrate that Mutator foci intensity is modulated by the stage of the germline cell cycle and specifically, that Mutator foci are brightest and most robust in the mitotic cells, transition zone, and late pachytene of adult germlines. Thus, our data defines several new factors that modulate Mutator foci morphology which may ultimately have implications for efficacy of RNAi in certain cell stages or environments.
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Affiliation(s)
- Celja J Uebel
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
| | - Dana Agbede
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
| | - Dylan C Wallis
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
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10
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Rogers AK, Phillips CM. A Small-RNA-Mediated Feedback Loop Maintains Proper Levels of 22G-RNAs in C. elegans. Cell Rep 2020; 33:108279. [PMID: 33086057 PMCID: PMC7603289 DOI: 10.1016/j.celrep.2020.108279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 08/27/2020] [Accepted: 09/24/2020] [Indexed: 02/06/2023] Open
Abstract
RNA interference (RNAi) is an essential regulatory mechanism in all animals. In Caenorhabditis elegans, several classes of small RNAs act to silence or license expression of mRNA targets. ERI-6/7 is required for the production of some endogenous small interfering RNAs (siRNAs) and acts as a negative regulator of the exogenous RNAi pathway. We find that the genomic locus encoding eri-6/7 contains two distinct regions that are targeted by endogenous siRNAs. Loss of these siRNAs disrupts eri-6/7 mRNA expression, resulting in increased production of siRNAs from other small RNA pathways because these pathways compete with eri-6/7-dependent transcripts for access to the downstream siRNA amplification machinery. Thus, the pathway acts like a small-RNA-mediated feedback loop to ensure homeostasis of gene expression by small RNA pathways. Similar feedback loops that maintain chromatin homeostasis have been identified in yeast and Drosophila melanogaster, suggesting an evolutionary conservation of feedback mechanisms in gene regulatory pathways.
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Affiliation(s)
- Alicia K Rogers
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.
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11
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Svendsen JM, Reed KJ, Vijayasarathy T, Montgomery BE, Tucci RM, Brown KC, Marks TN, Nguyen DAH, Phillips CM, Montgomery TA. henn-1/HEN1 Promotes Germline Immortality in Caenorhabditis elegans. Cell Rep 2020; 29:3187-3199.e4. [PMID: 31801082 PMCID: PMC6922003 DOI: 10.1016/j.celrep.2019.10.114] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 09/28/2019] [Accepted: 10/28/2019] [Indexed: 12/21/2022] Open
Abstract
The germline contains an immortal cell lineage that ensures the faithful transmission of genetic and, in some instances, epigenetic information from one generation to the next. Here, we show that in Caenorhabditis elegans, the small RNA 3′-2′-O-methyltransferase henn-1/HEN1 is required for sustained fertility across generations. In the absence of henn-1, animals become progressively less fertile, becoming sterile after ~30 generations at 25°C. Sterility in henn-1 mutants is accompanied by severe defects in germline proliferation and maintenance. The requirement for henn-1 in transgenerational fertility is likely due to its role in methylating and, thereby, stabilizing Piwi-interacting RNAs (piRNAs). However, despite being essential for piRNA stability in embryos, henn-1 is not required for piRNA stability in adults. Thus, we propose that methylation is important for the role of piRNAs in establishing proper gene silencing during early stages of development but is dispensable for their role in the proliferated germline. Svendsen et al. identify a requirement for the small RNA methyltransferase HENN-1 in germline immortality. HENN-1 is required for piRNA stability during embryogenesis but is dispensable in the adult germline, pointing to a role for piRNAs in establishing a gene regulatory network in embryos that protects the germline throughout development.
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Affiliation(s)
- Joshua M Svendsen
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA; Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 80523, USA
| | - Kailee J Reed
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA; Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 80523, USA
| | - Tarah Vijayasarathy
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Brooke E Montgomery
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Rachel M Tucci
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Kristen C Brown
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA; Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 80523, USA
| | - Taylor N Marks
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Dieu An H Nguyen
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Taiowa A Montgomery
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
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12
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Rogers AK, Phillips CM. RNAi pathways repress reprogramming of C. elegans germ cells during heat stress. Nucleic Acids Res 2020; 48:4256-4273. [PMID: 32187370 PMCID: PMC7192617 DOI: 10.1093/nar/gkaa174] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 03/02/2020] [Accepted: 03/10/2020] [Indexed: 01/08/2023] Open
Abstract
Repression of cellular reprogramming in germ cells is critical to maintaining cell fate and fertility. When germ cells mis-express somatic genes they can be directly converted into other cell types, resulting in loss of totipotency and reproductive potential. Identifying the molecular mechanisms that coordinate these cell fate decisions is an active area of investigation. Here we show that RNAi pathways play a key role in maintaining germline gene expression and totipotency after heat stress. By examining transcriptional changes that occur in mut-16 mutants, lacking a key protein in the RNAi pathway, at elevated temperature we found that genes normally expressed in the soma are mis-expressed in germ cells. Furthermore, these genes displayed increased chromatin accessibility in the germlines of mut-16 mutants at elevated temperature. These findings indicate that the RNAi pathway plays a key role in preventing aberrant expression of somatic genes in the germline during heat stress. This regulation occurs in part through the maintenance of germline chromatin, likely acting through the nuclear RNAi pathway. Identification of new pathways governing germ cell reprogramming is critical to understanding how cells maintain proper gene expression and may provide key insights into how cell identity is lost in some germ cell tumors.
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Affiliation(s)
- Alicia K Rogers
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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13
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Winkenbach LP, Doser R, Reed KJ, Pasquinelli AE, Phillips CM, Claycomb JM. Todos Santos small RNA symposium. RNA Biol 2019; 16:1526-1530. [PMID: 31397621 DOI: 10.1080/15476286.2019.1649586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Worm biologists from the United States, Canada, and the United Kingdom gathered at the Colorado State University Todos Santos Center in Baja California Sur, Mexico, April 3-5, 2019 for the Todos Santos Small RNA Symposium. Meeting participants, many of whom were still recovering from the bomb cyclone that struck a large swath of North America just days earlier, were greeted by the warmth and sunshine that is nearly ubiquitous in the sleepy seaside town of Todos Santos. With only 24 speakers, the meeting had the sort of laid-back vibe you might expect amongst the palm trees and ocean breeze of the Pacific coast of Mexico. The meeting started with tracing the laboratory lineages of participants. Not surprisingly, the most common parental lineages represented at the meeting were Dr. Craig Mello, Dr. Gary Ruvkun, and Dr. Victor Ambros, whom, together with Dr. Andy Fire and Dr. David Baulcombe, pioneered the small RNA field. In sad irony, on the closing day of the meeting, participants were met with the news of Dr. Sydney Brenner's passing. By establishing the worm, Caenorhabditis elegans, as a model system Dr. Brenner paved the way for much of the research discussed here.
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Affiliation(s)
- Lindsay P Winkenbach
- Department of Biochemistry and Molecular Biology, Colorado State University , Fort Collins , CO , USA
| | - Rachel Doser
- Department of Biomedical Sciences, Colorado State University , Fort Collins , CO , USA
| | - Kailee J Reed
- Department of Biology, Colorado State University , Fort Collins , CO , USA.,Cell and Molecular Biology Program, Colorado State University , Fort Collins , CO , USA
| | - Amy E Pasquinelli
- Division of Biology, University of California , San Diego , CA , USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California , Los Angeles , CA , USA
| | - Julie M Claycomb
- Department of Molecular Genetics, University of Toronto , Toronto , ON , Canada
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14
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Uebel CJ, Phillips CM. Phase-separated protein dynamics are affected by fluorescent tag choice. MicroPubl Biol 2019; 2019:143. [PMID: 32440657 PMCID: PMC7241484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Celja J Uebel
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
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15
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Wan G, Fields BD, Spracklin G, Shukla A, Phillips CM, Kennedy S. Spatiotemporal regulation of liquid-like condensates in epigenetic inheritance. Nature 2018; 557:679-683. [PMID: 29769721 PMCID: PMC6479227 DOI: 10.1038/s41586-018-0132-0] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 04/10/2018] [Indexed: 11/09/2022]
Abstract
Non-membrane bound organelles such as nucleoli, processing bodies, cajal bodies, and germ granules form via spontaneous self-assembly of specific proteins and RNAs. How these biomolecular condensates form and interact are poorly understood. Here we identify two proteins, ZNFX-1 and WAGO-4, that localize to C. elegans germ granules (P granules) in early germline blastomeres. Later in germline development, ZNFX-1/WAGO-4 separate from P granules to define an independent liquid-like condensate that we term the Z granule. In adult germ cells, Z granules assemble into ordered tri-condensate assemblages with P granules and Mutator foci, which we term the PZM granule. Finally, we show that one biological function of ZNFX-1 and WAGO-4 is to interact with silencing RNAs in the C. elegans germline to direct transgenerational epigenetic inheritance (TEI). We speculate that the temporal and spatial ordering of liquid droplet organelles may help cells organize and coordinate the complex RNA processing pathways underlying gene regulatory systems, such as RNA-directed TEI.
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Affiliation(s)
- Gang Wan
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Brandon D Fields
- Department of Genetics, Harvard Medical School, Boston, MA, USA.,Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - George Spracklin
- Department of Genetics, Harvard Medical School, Boston, MA, USA.,Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Aditi Shukla
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Carolyn M Phillips
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Scott Kennedy
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
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McParland D, Phillips CM, Brennan L, Roche HM, Gormley IC. Clustering high-dimensional mixed data to uncover sub-phenotypes: joint analysis of phenotypic and genotypic data. Stat Med 2017; 36:4548-4569. [PMID: 28664564 DOI: 10.1002/sim.7371] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 04/28/2017] [Accepted: 05/23/2017] [Indexed: 12/31/2022]
Abstract
The LIPGENE-SU.VI.MAX study, like many others, recorded high-dimensional continuous phenotypic data and categorical genotypic data. LIPGENE-SU.VI.MAX focuses on the need to account for both phenotypic and genetic factors when studying the metabolic syndrome (MetS), a complex disorder that can lead to higher risk of type 2 diabetes and cardiovascular disease. Interest lies in clustering the LIPGENE-SU.VI.MAX participants into homogeneous groups or sub-phenotypes, by jointly considering their phenotypic and genotypic data, and in determining which variables are discriminatory. A novel latent variable model that elegantly accommodates high dimensional, mixed data is developed to cluster LIPGENE-SU.VI.MAX participants using a Bayesian finite mixture model. A computationally efficient variable selection algorithm is incorporated, estimation is via a Gibbs sampling algorithm and an approximate BIC-MCMC criterion is developed to select the optimal model. Two clusters or sub-phenotypes ('healthy' and 'at risk') are uncovered. A small subset of variables is deemed discriminatory, which notably includes phenotypic and genotypic variables, highlighting the need to jointly consider both factors. Further, 7 years after the LIPGENE-SU.VI.MAX data were collected, participants underwent further analysis to diagnose presence or absence of the MetS. The two uncovered sub-phenotypes strongly correspond to the 7-year follow-up disease classification, highlighting the role of phenotypic and genotypic factors in the MetS and emphasising the potential utility of the clustering approach in early screening. Additionally, the ability of the proposed approach to define the uncertainty in sub-phenotype membership at the participant level is synonymous with the concepts of precision medicine and nutrition. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- D McParland
- School of Mathematics and Statistics, University College Dublin, Dublin, Ireland
| | - C M Phillips
- HRB Centre for Diet and Health Research, Department of Epidemiology and Public Health, University College Cork, Cork, Ireland.,HRB Centre for Diet and Health Research, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,Nutrigenomics Research Group, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - L Brennan
- School of Agriculture and Food Science, UCD Institute of Food and Health, University College Dublin, Dublin, Ireland
| | - H M Roche
- Nutrigenomics Research Group, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - I C Gormley
- School of Mathematics and Statistics, University College Dublin, Dublin, Ireland.,INSIGHT: The National Centre for Data Analytics, University College Dublin, Dublin, Ireland
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Millar SR, Perry IJ, Phillips CM. OP01 Assessing cardiometabolic risk in middle-aged adults using body mass index and waist-height ratio – are two indices better than one? Br J Soc Med 2015. [DOI: 10.1136/jech-2015-206256.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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18
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Millar SR, Perry IJ, Phillips CM. PP04 General and central obesity measurement associations with markers of chronic low-grade inflammation and type 2 diabetes. Br J Soc Med 2015. [DOI: 10.1136/jech-2015-206256.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Phillips CM, Brown KC, Montgomery BE, Ruvkun G, Montgomery TA. piRNAs and piRNA-Dependent siRNAs Protect Conserved and Essential C. elegans Genes from Misrouting into the RNAi Pathway. Dev Cell 2015; 34:457-65. [PMID: 26279487 DOI: 10.1016/j.devcel.2015.07.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 04/27/2015] [Accepted: 07/16/2015] [Indexed: 10/23/2022]
Abstract
piRNAs silence foreign genes, such as transposons, to preserve genome integrity, but they also target endogenous mRNAs by mechanisms that are poorly understood. Caenorhabditis elegans piRNAs interact with both transposon and nontransposon mRNAs to initiate sustained silencing via the RNAi pathway. To assess the dysregulation of gene silencing caused by lack of piRNAs, we restored RNA silencing in RNAi-defective animals in the presence or absence of piRNAs. In the absence of piRNAs and a cellular memory of piRNA activity, essential and conserved genes are misrouted into the RNAi pathway to produce siRNAs that bind the nuclear Argonaute HRDE-1, resulting in dramatic defects in germ cell proliferation and function such that the animals are sterile. Inactivation of RNAi suppresses sterility, indicating that aberrant siRNAs produced in the absence of piRNAs target essential genes for silencing. Thus, by reanimating RNAi, we uncovered a role for piRNAs in protecting essential genes from RNA silencing.
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Affiliation(s)
- Carolyn M Phillips
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA
| | - Kristen C Brown
- Department of Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, CO 80523, USA; Cell and Molecular Biology Program, Colorado State University, 1005 Campus Delivery, Fort Collins, CO 80523, USA
| | - Brooke E Montgomery
- Department of Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, CO 80523, USA
| | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA.
| | - Taiowa A Montgomery
- Department of Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, CO 80523, USA.
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Millar SR, Perry IJ, Van den Broeck J, Phillips CM. PP68 Optimal central obesity measurement site for assessing cardiometabolic and type 2 diabetes risk in middle-aged adults. Br J Soc Med 2014. [DOI: 10.1136/jech-2014-204726.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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21
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Millar SR, Perry IJ, Phillips CM. PP12 Cardiometabolic risk profiles in pre-diabetes and diabetes defined by fasting plasma glucose and HbA 1clevels in middle-aged adults. Br J Soc Med 2014. [DOI: 10.1136/jech-2014-204726.109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Delgado-Lista J, Perez-Martinez P, Garcia-Rios A, Phillips CM, Hall W, Gjelstad IMF, Lairon D, Saris W, Kieć-Wilk B, Karlström B, Drevon CA, Defoort C, Blaak EE, Dembinska-Kieć A, Risérus U, Lovegrove JA, Roche HM, Lopez-Miranda J. A gene variation (rs12691) in the CCAT/enhancer binding protein α modulates glucose metabolism in metabolic syndrome. Nutr Metab Cardiovasc Dis 2013; 23:417-423. [PMID: 22269963 DOI: 10.1016/j.numecd.2011.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 09/20/2011] [Accepted: 09/23/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS CCAAT/enhancer-binding protein alpha (CEBPA) is a transcription factor involved in adipogenesis and energy homeostasis. Caloric restriction reduces CEBPA protein expression in patients with metabolic syndrome (MetS). A previous report linked rs12691 SNP in CEBPA to altered concentration of fasting triglycerides. Our objective was to assess the effects of rs12691 in glucose metabolism in Metabolic Syndrome (MetS) patients. METHODS AND RESULTS Glucose metabolism was assessed by static (glucose, insulin, adiponectin, leptin and resistin plasma concentrations) and dynamic (disposition index, insulin sensitivity index, HOMA-IR and acute insulin response to glucose) indices, performed at baseline and after 12 weeks of 4 dietary interventions (high saturated fatty acid (SFA), high monounsaturated fatty acid (MUFA), low-fat and low-fat-high-n3 polyunsaturated fatty acid (PUFA)) in 486 subjects with MetS. Carriers of the minor A allele of rs12691 had altered disposition index (p = 0.0003), lower acute insulin response (p = 0.005) and a lower insulin sensitivity index (p = 0.025) indicating a lower insulin sensitivity and a lower insulin secretion, at baseline and at the end of the diets. Furthermore, A allele carriers displayed lower HDL concentration. CONCLUSION The presence of the A allele of rs12691 influences glucose metabolism of MetS patients.
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Affiliation(s)
- J Delgado-Lista
- Lipids and Atherosclerosis Unit, Department of Medicine, IMIBIC/Hospital Universitario Reina Sofía/Universidad de Córdoba, Cordoba, Spain; CIBER Fisiopatologia Obesidad y Nutricion (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
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Phillips CM, Montgomery TA, Breen PC, Ruvkun G. MUT-16 promotes formation of perinuclear mutator foci required for RNA silencing in the C. elegans germline. Genes Dev 2012; 26:1433-44. [PMID: 22713602 DOI: 10.1101/gad.193904.112] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
RNA silencing can be initiated by endogenous or exogenously delivered siRNAs. In Caenorhabditis elegans, RNA silencing guided by primary siRNAs is inefficient and therefore requires an siRNA amplification step involving RNA-dependent RNA polymerases (RdRPs). Many factors involved in RNA silencing localize to protein- and RNA-rich nuclear pore-associated P granules in the germline, where they are thought to surveil mRNAs as they exit the nucleus. Mutator class genes are required for siRNA-mediated RNA silencing in both germline and somatic cells, but their specific roles and relationship to other siRNA factors are unclear. Here we show that each of the six mutator proteins localizes to punctate foci at the periphery of germline nuclei. The Mutator foci are adjacent to P granules but are not dependent on core P-granule components or other RNAi pathway factors for their formation or stability. The glutamine/asparagine (Q/N)-rich protein MUT-16 is specifically required for the formation of a protein complex containing the mutator proteins, and in its absence, Mutator foci fail to form at the nuclear periphery. The RdRP RRF-1 colocalizes with MUT-16 at Mutator foci, suggesting a role for Mutator foci in siRNA amplification. Furthermore, we demonstrate that genes that yield high levels of siRNAs, indicative of multiple rounds of siRNA amplification, are disproportionally affected in mut-16 mutants compared with genes that yield low levels of siRNAs. We propose that the mutator proteins and RRF-1 constitute an RNA processing compartment required for siRNA amplification and RNA silencing.
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Affiliation(s)
- Carolyn M Phillips
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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Montgomery TA, Rim YS, Zhang C, Dowen RH, Phillips CM, Fischer SEJ, Ruvkun G. PIWI associated siRNAs and piRNAs specifically require the Caenorhabditis elegans HEN1 ortholog henn-1. PLoS Genet 2012; 8:e1002616. [PMID: 22536158 PMCID: PMC3334881 DOI: 10.1371/journal.pgen.1002616] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 02/03/2012] [Indexed: 12/29/2022] Open
Abstract
Small RNAs--including piRNAs, miRNAs, and endogenous siRNAs--bind Argonaute proteins to form RNA silencing complexes that target coding genes, transposons, and aberrant RNAs. To assess the requirements for endogenous siRNA formation and activity in Caenorhabditis elegans, we developed a GFP-based sensor for the endogenous siRNA 22G siR-1, one of a set of abundant siRNAs processed from a precursor RNA mapping to the X chromosome, the X-cluster. Silencing of the sensor is also dependent on the partially complementary, unlinked 26G siR-O7 siRNA. We show that 26G siR-O7 acts in trans to initiate 22G siRNA formation from the X-cluster. The presence of several mispairs between 26G siR-O7 and the X-cluster mRNA, as well as mutagenesis of the siRNA sensor, indicates that siRNA target recognition is permissive to a degree of mispairing. From a candidate reverse genetic screen, we identified several factors required for 22G siR-1 activity, including the chromatin factors mes-4 and gfl-1, the Argonaute ergo-1, and the 3' methyltransferase henn-1. Quantitative RT-PCR of small RNAs in a henn-1 mutant and deep sequencing of methylated small RNAs indicate that siRNAs and piRNAs that associate with PIWI clade Argonautes are methylated by HENN-1, while siRNAs and miRNAs that associate with non-PIWI clade Argonautes are not. Thus, PIWI-class Argonaute proteins are specifically adapted to associate with methylated small RNAs in C. elegans.
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Affiliation(s)
| | | | | | | | | | | | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
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Phillips CM, Odekunle A. The organization of the brainstem nuclei associated with the vagus nerve in the Agouti (Dasyprocta leporina). A neurohistological study. W INDIAN MED J 2011; 60:46-52. [PMID: 21809711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A total of six adult animals were used for the study. Following anaesthesia via intraperitoneal injection of a mixture of ketamin and bombazine in ratio 2:1, thoracotomy was performed to exteriorize the heart for intracardial perfusion. The perfusion canular was inserted into the left ventricle and animal perfused sequentially with normal saline and 10% formal saline. Following perfusion, craniotomy was performed to remove the entire brain along with the upper segments of the spinal cord. The brain specimen was then dehydrated, cleared and infiltrated with paraffin wax. The specimen was then cut in 15 micron thick serial sections. The sections were then processed for neurohistological analyses using a Nikon microscope to which was attached Nikon camera. Analyses of the sections revealed bilateral representation of the dorsal motor nucleus of the vagus nerve in the medulla oblongata. The nucleus ambiguus, nucleus of the tractus solitarius, hypoglossal nucleus and the area postrema were also identified in the medulla oblongata. The implications of our findings are discussed in the text of the article.
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Affiliation(s)
- C M Phillips
- Anatomy Unit, Department of Preclinical Sciences, Faculty of Medical Sciences, The University of the West Indies, St Augustine Campus, Trinidad and Tobago
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26
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Delgado-Lista J, Perez-Martinez P, García-Rios A, Phillips CM, Williams CM, Gulseth HL, Helal O, Blaak EE, Kiec-Wilk B, Basu S, Drevon CA, Defoort C, Saris WH, Wybranska I, Riserus U, Lovegrove JA, Roche HM, Lopez-Miranda J. Pleiotropic effects of TCF7L2 gene variants and its modulation in the metabolic syndrome: from the LIPGENE study. Atherosclerosis 2010; 214:110-6. [PMID: 21115178 DOI: 10.1016/j.atherosclerosis.2010.10.027] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 10/05/2010] [Accepted: 10/24/2010] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS Variants of the TCF7L2 gene predict the development of type 2 diabetes mellitus (T2DM). We investigated the associations between gene variants of TCF7L2 and clinical features of the metabolic syndrome (MetS) (an entity often preceding T2DM), and their interaction with non-genetic factors, including plasma saturated fatty acids (SFA) concentration and insulin resistance (IR). METHODS Fasting lipid profiles, insulin sensitivity, insulin secretion, anthropometrics, blood pressure and 10 gene variations of the TCF7L2 gene were determined in 450 subjects with MetS. RESULTS Several single nucleotide polymorphisms (SNP) showed phenotypic associations independent of SFA or IR. Carriers of the rare T allele of rs7903146, and of three other SNPs in linkage disequilibrium with rs7903146, had lower blood pressure and insulin secretion. High IR and the presence of the T-allele of rs7903146 acted synergistically to define those with reduced insulin secretion. Carriers of the minor allele of rs290481 exhibited an altered lipid profile, with increased plasma levels of apolipoprotein B, non-esterified fatty acids, cholesterol and apolipoprotein B in triglyceride rich lipoproteins, and LDL cholesterol. Carriers of the minor allele of rs11196224 that had higher plasma SFA levels showed elevated procoagulant/proinflammatory biomarkers, impaired insulin secretion and increased IR, whereas carriers of the minor allele of rs17685538 with high plasma SFA levels exhibited higher blood pressure. CONCLUSIONS/INTERPRETATION SNP in the TCF7L2 gene are associated with differences in insulin secretion, blood pressure, blood lipids and coagulation in MetS patients, and may be modulated by SFA in plasma or IR.
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Affiliation(s)
- J Delgado-Lista
- Hospital Universitario Reina Sofía, Universidad de Córdoba and CIBER Fisiopatología Obesidad y Nutrición CIBEROBN, Instituto de Salud Carlos III, 14004 Córdoba, Spain
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Sato A, Isaac B, Phillips CM, Rillo R, Carlton PM, Wynne DJ, Kasad RA, Dernburg AF. Cytoskeletal forces span the nuclear envelope to coordinate meiotic chromosome pairing and synapsis. Cell 2009; 139:907-19. [PMID: 19913287 DOI: 10.1016/j.cell.2009.10.039] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 08/04/2009] [Accepted: 10/28/2009] [Indexed: 11/17/2022]
Abstract
During meiosis, each chromosome must pair with its unique homologous partner, a process that usually culminates with the formation of the synaptonemal complex (SC). In the nematode Caenorhabditis elegans, special regions on each chromosome known as pairing centers are essential for both homologous pairing and synapsis. We report that during early meiosis, pairing centers establish transient connections to the cytoplasmic microtubule network. These connections through the intact nuclear envelope require the SUN/KASH domain protein pair SUN-1 and ZYG-12. Disruption of microtubules inhibits chromosome pairing, indicating that these connections promote interhomolog interactions. Dynein activity is essential to license formation of the SC once pairing has been accomplished, most likely by overcoming a barrier imposed by the chromosome-nuclear envelope connection. Our findings thus provide insight into how homolog pairing is accomplished in meiosis and into the mechanisms regulating synapsis so that it occurs selectively between homologs. For a video summary of this article, see the PaperFlick file with the Supplemental Data available online.
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Affiliation(s)
- Aya Sato
- Howard Hughes Medical Institute, Chevy Chase, MD 20815 USA
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Mayer ML, Phillips CM, Townsend RA, Halperin SA, Lee SF. Differential activation of dendritic cells by Toll-like receptor agonists isolated from the Gram-positive vaccine vector Streptococcus gordonii. Scand J Immunol 2009; 69:351-6. [PMID: 19284500 DOI: 10.1111/j.1365-3083.2009.02232.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The oral commensal bacterium Streptococcus gordonii has been gathering interest as a candidate live mucosal vaccine delivery vector. S. gordonii has been shown to be capable of activating antigen presenting immune cells in a manner which leads to their activation and maturation, yet the mechanism used by S. gordonii to do so is poorly understood. The aim of this work was to investigate the immunostimulatory components of S. gordonii in inducing murine dendritic cell (DC) activation and maturation. Lipoteichoic acid (LTA), lipoprotein (LP), peptidoglycan (PGN), and DNA were isolated from S. gordonii, and used to stimulate murine DC. Cytokine production and DC surface marker upregulation in response to the bacterial components was quantified by enzyme-linked immunosorbent assay and flow cytometry respectively. The results were contrasted against data obtained from DC derived from MyD88, TRIF [TIR(Toll/Interleukin-1 Receptor)-domain-containing adapter-inducing interferon-beta] or toll-like receptor-2 (TLR-2) knockout mice. The four S. gordonii bacterial components were found to differentially induce cytokine production and surface marker upregulation by murine DC. Activation of DC by both whole S. gordonii cells and the four bacterial components was abrogated in the absence of MyD88, but not in the absence of TRIF. LTA, LP and PGN, but not DNA and whole S. gordonii, required TLR-2 to induce a DC response. The results collectively indicate that S. gordonii activates DC predominantly through a MyD88-dependent and TRIF-independent pathway. This activation can be attributed to multiple immunostimulatory components present within S. gordonii bacterial cells.
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Affiliation(s)
- M L Mayer
- Canadian Center for Vaccinology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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Dernburg AF, Phillips CM, Sato A. Chromosome dynamics during meiosis. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.396.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Abby F Dernburg
- Molecular and Cell BiologyUC Berkeley and Lawrence Berkeley National LabBerkeleyCA
| | | | - Aya Sato
- Molecular and Cell BiologyUC BerkeleyBerkeleyCA
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Phillips CM, Dernburg AF. A family of zinc-finger proteins is required for chromosome-specific pairing and synapsis during meiosis in C. elegans. Dev Cell 2007; 11:817-29. [PMID: 17141157 DOI: 10.1016/j.devcel.2006.09.020] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 09/08/2006] [Accepted: 09/25/2006] [Indexed: 11/23/2022]
Abstract
Homologous chromosome pairing and synapsis are prerequisite for accurate chromosome segregation during meiosis. Here, we show that a family of four related C2H2 zinc-finger proteins plays a central role in these events in C. elegans. These proteins are encoded within a tandem gene cluster. In addition to the X-specific HIM-8 protein, three additional paralogs collectively mediate the behavior of the five autosomes. Each chromosome relies on a specific member of the family to pair and synapse with its homolog. These "ZIM" proteins concentrate at special regions called meiotic pairing centers on the corresponding chromosomes. These sites are dispersed along the nuclear envelope during early meiotic prophase, suggesting a role analogous to the telomere-mediated meiotic bouquet in other organisms. To gain insight into the evolution of these components, we characterized homologs in C. briggsae and C. remanei, which revealed changes in copy number of this gene family within the nematode lineage.
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Affiliation(s)
- Carolyn M Phillips
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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MacQueen AJ, Phillips CM, Bhalla N, Weiser P, Villeneuve AM, Dernburg AF. Chromosome sites play dual roles to establish homologous synapsis during meiosis in C. elegans. Cell 2006; 123:1037-50. [PMID: 16360034 PMCID: PMC4435800 DOI: 10.1016/j.cell.2005.09.034] [Citation(s) in RCA: 221] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 07/27/2005] [Accepted: 09/13/2005] [Indexed: 10/25/2022]
Abstract
We have investigated the role of pairing centers (PCs), cis-acting sites required for accurate segregation of homologous chromosomes during meiosis in C. elegans. We find that these sites play two distinct roles that contribute to proper segregation. Chromosomes lacking PCs usually fail to synapse and also lack a synapsis-independent stabilization activity. The presence of a PC on just one copy of a chromosome pair promotes synapsis but does not support synapsis-independent pairing stabilization, indicating that these functions are separable. Once initiated, synapsis is highly processive, even between nonhomologous chromosomes of disparate lengths, elucidating how translocations suppress meiotic recombination in C. elegans. These findings suggest a multistep pathway for chromosome synapsis in which PCs impart selectivity and efficiency through a "kinetic proofreading" mechanism. We speculate that concentration of these activities at one region per chromosome may have coevolved with the loss of a point centromere to safeguard karyotype stability.
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Affiliation(s)
- Amy J. MacQueen
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Carolyn M. Phillips
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Needhi Bhalla
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Pinky Weiser
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Anne M. Villeneuve
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Abby F. Dernburg
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Contact:
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Phillips CM, Wong C, Bhalla N, Carlton PM, Weiser P, Meneely PM, Dernburg AF. HIM-8 binds to the X chromosome pairing center and mediates chromosome-specific meiotic synapsis. Cell 2006; 123:1051-63. [PMID: 16360035 PMCID: PMC4435792 DOI: 10.1016/j.cell.2005.09.035] [Citation(s) in RCA: 240] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 07/27/2005] [Accepted: 09/13/2005] [Indexed: 11/22/2022]
Abstract
The him-8 gene is essential for proper meiotic segregation of the X chromosomes in C. elegans. Here we show that loss of him-8 function causes profound X chromosome-specific defects in homolog pairing and synapsis. him-8 encodes a C2H2 zinc-finger protein that is expressed during meiosis and concentrates at a site on the X chromosome known as the meiotic pairing center (PC). A role for HIM-8 in PC function is supported by genetic interactions between PC lesions and him-8 mutations. HIM-8 bound chromosome sites associate with the nuclear envelope (NE) throughout meiotic prophase. Surprisingly, a point mutation in him-8 that retains both chromosome binding and NE localization fails to stabilize pairing or promote synapsis. These observations indicate that stabilization of homolog pairing is an active process in which the tethering of chromosome sites to the NE may be necessary but is not sufficient.
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Affiliation(s)
- Carolyn M. Phillips
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Chihunt Wong
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Needhi Bhalla
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Peter M. Carlton
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Pinky Weiser
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Abby F. Dernburg
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Contact:
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Collins-Schramm HE, Phillips CM, Operario DJ, Lee JS, Weber JL, Hanson RL, Knowler WC, Cooper R, Li H, Seldin MF. Ethnic-difference markers for use in mapping by admixture linkage disequilibrium. Am J Hum Genet 2002; 70:737-50. [PMID: 11845411 PMCID: PMC384950 DOI: 10.1086/339368] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2001] [Accepted: 12/20/2001] [Indexed: 11/03/2022] Open
Abstract
Mapping by admixture linkage disequilibrium (MALD) is a potentially powerful technique for the mapping of complex genetic diseases. The practical requirements of this method include (a) a set of markers spanning the genome that have large allele-frequency differences between the parental ethnicities contributing to the admixed population and (b) an understanding of the extent of admixture in the study population. To this end, a DNA-pooling technique was used to screen microsatellite and diallelic insertion/deletion markers for allele-frequency differences between putative representatives of the parental populations of the admixed Mexican American (MA) and African American (AA) populations. Markers with promising pooled differences were then confirmed by individual genotyping in both the parental and admixed populations. For the MA population, screening of >600 markers identified 151 ethnic-difference markers (EDMs) with delta>0.30 (where delta is the absolute value of each allele-frequency difference between two populations, summed over all marker alleles and divided by two) that are likely to be useful for MALD analysis. For the AA population, analysis of >400 markers identified 97 EDMs. In addition, individual genotyping of these markers in Pima Amerindians, Yavapai Amerindians, European American (EA) individuals, Africans from Zimbabwe, MA individuals, and AA individuals, as well as comparison to the CEPH genotyping set, suggests that the differences between subpopulations of an ethnicity are small for many markers with large interethnic differences. Estimates of admixture that are based on individual genotyping of these markers are consistent with a 60% EA:40% Amerindian contribution to MA populations and with a 20% EA:80% African contribution to AA populations. Taken together, these data suggest that EDMs with large interpopulation and small intrapopulation differences can be readily identified for MALD studies in both AA and MA populations.
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Affiliation(s)
- Heather E. Collins-Schramm
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - Carolyn M. Phillips
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - Darwin J. Operario
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - Jane S. Lee
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - James L. Weber
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - Robert L. Hanson
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - William C. Knowler
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - Richard Cooper
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - Hongzhe Li
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
| | - Michael F. Seldin
- Rowe Program in Human Genetics, Department of Biological Chemistry and Medicine, University of California at Davis; Center for Medical Genetics, Marshfield Medical Research Foundation, Marshfield, WI; National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix; and Department of Preventive Medicine and Epidemiology, Loyola University, Maywood, IL
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Abstract
OBJECTIVE There are racial differences in adolescents' propensity to consume alcohol--with white adolescents tending to consume more alcohol than black adolescents--but there is no clear explanation for why such differences exist. The purpose of this study was to examine the relationship between religiosity, a cultural factor that is not well understood currently, and racial differences in adolescent alcohol use. METHOD Participants were white and black ninth-grade adolescents (N = 899; 54% female, 57.5% white) involved in a 3-year longitudinal study of ways to reduce alcohol use and sexual risk-taking behavior among adolescents in Ohio and Kentucky. RESULTS Findings indicate that religiosity is differentially associated with alcohol use and problem drinking for white and black adolescents. Religious service attendance was the most significant predictor of alcohol use for black adolescents, whereas religious fundamentalism was most important for white adolescents. In contrast, frequency of prayer was the significant predictor of problem drinking for black adolescents, whereas the level of importance placed on religion was the significant predictor for white adolescents. Important gender differences also emerged in both prediction models and are discussed. CONCLUSIONS Since there is great heterogeneity among adolescents (in terms of race and gender) in their alcohol use and misuse, the "one-size-fits-all" approach to alcohol treatment and prevention is likely inappropriate. Moreover, conceptualizations of alcohol use and misuse, and its prevention and treatment, should include the consideration of such key cultural factors as religiosity.
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Affiliation(s)
- T L Brown
- Department of Psychology, University of Kentucky, Lexington 40506-0044, USA.
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Bushman BJ, Baumeister RF, Phillips CM. Do people aggress to improve their mood? Catharsis beliefs, affect regulation opportunity, and aggressive responding. J Pers Soc Psychol 2001; 81:17-32. [PMID: 11474722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Do people aggress to make themselves feel better? We adapted a procedure used by G. K. Manucia, D. J. Baumann, and R. B. Cialdini (1984), in which some participants are given a bogus mood-freezing pill that makes affect regulation efforts ineffective. In Study 1, people who had been induced to believe in the value of catharsis and venting anger responded more aggressively than did control participants to insulting criticism, but this aggression was eliminated by the mood-freezing pill. Study 2 showed similar results among people with high anger-out (i.e., expressing and venting anger) tendencies. Studies 3 and 4 provided questionnaire data consistent with these interpretations, and Study 5 replicated the findings of Studies 1 and 2 using measures more directly concerned with affect regulation. Taken together, these results suggest that many people may engage in aggression to regulate (improve) their own affective states.
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Affiliation(s)
- B J Bushman
- Department of Psychology, Iowa State University, Ames 50011-3180, USA.
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Phillips CM, Murphy R, Burke WA, Laing VB, Jones BE, Balch D, Gustke S. Dermatology teleconsultations to Central Prison: experience at East Carolina University. Telemed J 1999; 2:139-43. [PMID: 10165356 DOI: 10.1089/tmj.1.1996.2.139] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To review our experience with dermatology teleconsultations between East Carolina University School of Medicine in Greenville and Central Prison in Raleigh, NC. MATERIALS AND METHODS Consultation forms kept on file in the Department of Internal Medicine served as the source of data. One physician reviewed the forms from the initial 22 months of our dermatology teleconsultation service to Central Prison. Patient demographics and the diagnoses made by the consulting physician were recorded. Recommendations were tabulated as either diagnostic or therapeutic. Diagnoses and recommendations for known HIV-positive individuals were separately recorded. RESULTS One hundred thirty-eight dermatology teleconsultations were performed over the 22-month period. Seventy two per cent of the patients seen were African-American. The average age was 32 years. One hundred fifty-nine diagnoses were made. The most common problems were eczema and acneiform eruptions. Fifty-nine diagnostic and 252 therapeutic recommendations were made. CONCLUSION Consultants generally were confident of their diagnoses and management decisions. Dermatologists can assist primary care physicians through telemedicine consultation.
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Affiliation(s)
- C M Phillips
- Department of Medicine, East Carolina University School of Medicine, Greenville, NC, USA
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Abstract
OBJECTIVES To determine the reliability of videoconferencing technology in evaluating skin tumors, the impact of the technology on the clinicians' degree of suspicion that a skin tumor is malignant, and the recommendation to do a biopsy. MATERIALS AND METHODS Four skin cancer screenings were conducted at rural health care facilities in eastern North Carolina that were connected to East Carolina University School of Medicine. A dermatologist saw the patients in person at the local facility, and the same patient was seen by a dermatologist via a T-1 connection to Greenville, North Carolina. RESULTS The two physicians were in absolute agreement on 59% of the 107 skin tumors evaluated. There were five lesions identified by the on-site dermatologist as a probable or definite malignancy. The degree of concern about a lesion being malignant and the decision whether to do a biopsy were not significantly different, as shown by kappa analysis. CONCLUSION The concern about the malignancy of a particular skin lesion and the recommendation whether to do a biopsy were not significantly affected by telemedicine technology.
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Affiliation(s)
- C M Phillips
- Section of Dermatology, East Carolina University School of Medicine, Greenville, NC, USA
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Phillips CM, Burke WA, Shechter A, Stone D, Balch D, Gustke S. Reliability of dermatology teleconsultations with the use of teleconferencing technology. J Am Acad Dermatol 1997; 37:398-402. [PMID: 9308553 DOI: 10.1016/s0190-9622(97)70139-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Recent advances in telecommunications technology allow physicians to consult on patients at a distance via an interactive video format. Few data exist as to the reliability of this form of consultation. OBJECTIVE Our purpose was to measure the degree of concordance between a dermatologist seeing a patient in a clinic and another dermatologist seeing the same patient over a commercially available videoconferencing system. METHODS Patients referred to a general dermatology clinic were seen by both a "live" dermatologist and a "teledermatologist" via a T1 connection. Diagnosis and recommendations were recorded by both physicians and compared. The physicians were also asked to rate the degree of confidence they had in their diagnosis. RESULTS Seventy-nine diagnoses were made on 60 patients. The two physicians were in absolute agreement on 61 of the diagnoses (77.2%). Race or sex of the patient, nature of the skin problems, or which of the two physicians was the teledermatologist did not statistically correlate with the concordance of the two physicians. CONCLUSION There was a reasonable degree of agreement between the two examining physicians. Despite the relatively high degree of concordance the teledermatologist had a significantly lower degree of confidence in his diagnoses.
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Affiliation(s)
- C M Phillips
- Section of Dermatology, East Carolina University, School of Medicine, Greenville, NC 27858-4354, USA
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Norton SA, Burdick AE, Phillips CM, Berman B. Teledermatology and underserved populations. Arch Dermatol 1997; 133:197-200. [PMID: 9041833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
BACKGROUND The dermatologic needs of many communities in the United States and worldwide are underserved. Telemedicine enables physicians and non-physician primary care providers to use modern telecommunications devices to gain access to specialist consultations promptly and with much less travel. The independently developed telemedicine programs described herein support 3 traditionally underserved populations: Pacific Islanders, migrant farmworkers, and prison inmates. OBSERVATIONS In 3 independently designed telemedicine programs, dermatology emerged as the specialty most used by remote practitioners. Patients were presented for both diagnosis and treatment and in the setting of initial evaluation and as part of follow-up care. CONCLUSION Teledermatology is a useful way to provide dermatologic support to remote or underserved communities.
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Affiliation(s)
- S A Norton
- Department of Medicine, Tripler Army Medical Center, Honolulu, Hawaii, USA
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Abstract
BACKGROUND Various hormonal states are known to be associated with the waxing and waning of psoriasis. Patients with psoriasis commonly experience changes in their cutaneous disease during pregnancy or post partum. OBJECTIVE We evaluated 100 women with psoriasis by questionnaire and interview. The women had been seen at the Baylor Psoriasis Center, Dallas, and had experienced a pregnancy while having psoriasis. The answers were sorted and tabulated. In addition, we reviewed the literature to ascertain possible causes of clinical changes in psoriasis during pregnancy. RESULTS Ninety questionnaires were completed. Sixty-nine women (76.7%) described a change in their psoriasis during pregnancy with 57 (63.3%) noting improvement. Seventy-nine patients (87.7%) had a postpartum flare, most within 4 months of delivery. CONCLUSIONS The majority of women with psoriasis, who become pregnant, experience a change, usually an improvement, in their cutaneous disease. Pregnancy is associated with hormonal changes in estrogens and progesterone resulting in a state of altered immune surveillance.
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Affiliation(s)
- A S Boyd
- Department of Dermatology, Vanderbilt University, Nashville, Tennessee 37232-5227, USA
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Abstract
A temperature jump (T-jump) method capable of initiating thermally induced processes on the picosecond time scale in aqueous solutions is introduced. Protein solutions are heated by energy from a laser pulse that is absorbed by homogeneously dispersed molecules of the dye crystal violet. These act as transducers by releasing the energy as heat to cause a T-jump of up to 10 K with a time resolution of 70 ps. The method was applied to the unfolding of RNase A. At pH 5.7 and 59 degrees C, a T-jump of 3-6 K induced unfolding which was detected by picosecond transient infrared spectroscopy of the amide I region between 1600 and 1700 cm-1. The difference spectral profile at 3.5 ns closely resembled that found for the equilibrium (native-unfolded) states. The signal at 1633 cm-1, corresponding to the beta-sheet structure, achieved 15 +/- 2% of the decrease found at equilibrium, within 5.5 ns. However, no decrease in absorbance was detected until 1 ns after the T-ump. The disruption of beta-sheet therefore appears to be subject to a delay of approximately 1 ns. Prior to 1 ns after the T-jump, water might be accessing the intact hydrophobic regions.
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Affiliation(s)
- C M Phillips
- Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA
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Sudhakar K, Phillips CM, Owen CS, Vanderkooi JM. Dynamics of parvalbumin studied by fluorescence emission and triplet absorption spectroscopy of tryptophan. Biochemistry 1995; 34:1355-63. [PMID: 7827083 DOI: 10.1021/bi00004a030] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Fluorescence emission and triplet-triplet absorbance spectroscopy of the single tryptophan in cod parvalbumin were used to study the stability and dynamics of the protein as influenced by Ca2+ binding and interaction with a chaotropic agent. The concentrations for half-saturation for Ca binding were 3.6 x 10(-9), 3.3 x 10(-4), 7.1 x 10(-3), and 0.14 M in the presence of 0, 2, 3, and 4 M guanidine hydrochloride, respectively. As predicted for thermodynamic reversibility, the guanidine hydrochloride unfolding reaction depends upon Ca2+, and the delta G are as follows: 22.9, 29.3, 35.2, and 44.2 kJ/mol for no added Ca2+, 1, 2, and 5 mM Ca2+, respectively. The stability toward denaturation imparted by the binding of two Ca2+ is about -60 kJ/mol. For Ca(2+)-bound parvalbumin in the presence of excess Ca2+, the decay of the triplet state tryptophan is approximately exponential, and the lifetime decreases from 6.5 to 3.8 ms as the temperature increases from 10 to 40 degrees C. In contrast, the triplet decay of the calcium-free protein is nonexponential over the time range of microseconds to milliseconds, a result that may indicate that the Ca-free protein is molten-globule-like. At Ca2+ concentrations where the protein is partially saturated with Ca2+, the lifetime of the longest decay component is less than that for the Ca-saturated protein; this finding suggests an exchange of Ca2+ and a conformational change during the triplet lifetime. From these data, a rate constant for the process that includes calcium-related protein conformational change can be surmised to range between 200 and 500 s-1.
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Affiliation(s)
- K Sudhakar
- Department of Biochemistry & Biophysics, School of Medicine of Pennsylvania, Philadelphia 19104
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Abstract
The authors conducted a time study of residents in clinic to determine the effects of providing clerical assistance. The residents recorded their activities at 5-minute intervals at baseline and six months after hiring three clerical assistants. Before and after introduction of the clerical assistants, approximately 40% of the time was devoted to direct interaction with patients. Statistically significant improvements were observed in the availability of medical records (89% vs 100%) and the time spent looking up test results (5% vs 3% of the clinic time). The residents felt the clerical assistants greatly improved their clinic experience and the quality of patient care.
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Affiliation(s)
- J E Wipf
- Section of General Internal Medicine, Seattle Veterans Affairs Medical Center, Washington 98108
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Sudhakar K, Phillips CM, Williams SA, Vanderkooi JM. Excited states of tryptophan in cod parvalbumin. Identification of a short-lived emitting triplet state at room temperature. Biophys J 1993; 64:1503-11. [PMID: 8324187 PMCID: PMC1262476 DOI: 10.1016/s0006-3495(93)81519-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The fluorescence and phosphorescence spectra of model indole compounds and of cod parvalbumin III, a protein containing a single tryptophan and no tyrosine, were examined in the time scale ranging from subnanoseconds to milliseconds at 25 degrees C in aqueous buffer. For both Ca- bound and Ca-free parvalbumin and for model indole compounds that contained a proton donor, a phosphorescent species emitting at 450 nm with a lifetime of approximately 20-40 ns could be identified. A longer-lived phosphorescence is also apparent; it has approximately the same absorption and emission spectrum as the short-lived triplet molecule. For Ca parvalbumin, the decay of the long-lived triplet tryptophan is roughly exponential with a lifetime of 4.7 ms at 25 degrees C whereas for N-acetyltryptophanamide in aqueous buffer the decay lifetime was 30 microseconds. In contrast, the lifetime of the long-lived tryptophan species is much shorter in the Ca-free protein compared with Ca parvalbumin, and the decay shows complex nonexponential kinetics over the entire time range from 100 ns to 1 ms. It is concluded that the photochemistry of tryptophan must take into account the existence of two excited triplet species and that there are quenching moieties within the protein matrix that decrease the phosphorescence yield in a dynamic manner for the Ca-depleted parvalbumin. In contrast, for Ca parvalbumin, the tryptophan site is rigid on the time scale of milliseconds.
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Affiliation(s)
- K Sudhakar
- Johnson Research Foundation, Department of Biochemistry and Biophysics, School of Medicine, Philadelphia, Pennsylvania
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Abstract
BACKGROUND The need for comparative cost figures for psoriasis therapy has become increasingly important. OBJECTIVE Our purpose was to compare the yearly costs of various psoriasis treatments. METHODS Ten patients were selected for each treatment modality and the average total cost per year, per patient was evaluated. RESULTS All treatments evaluated were cheaper than inpatient therapy, with Goeckerman treatment in the day-care setting the most expensive and hydroxyurea the cheapest. Cyclosporine, which was used for comparison, was at least twice as expensive as all the other treatments except for Goeckerman treatment in the day-care setting, compared with which it was about 70% more expensive. CONCLUSION No single treatment appears to be universally superior to others. In considering specific treatment for psoriasis, cost analyses, including appropriate laboratory and other specialized evaluations, must be taken into account. With use of these data, practitioners and health care organizations may be better able to select appropriate therapy.
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Affiliation(s)
- H M Sander
- Baylor Psoriasis Center, Dallas, TX 75246
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Lundie-Jenkins G, Corbett LK, Phillips CM. Ecology of the rufous hare-wallaby, Lagorchestes hirsutus Gould (Marsupialia : Macropodidae) in the Tanami Desert, Northern Territory. III Interactions with introduced mammal species. Wildl Res 1993. [DOI: 10.1071/wr9930495] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This paper reports a study of the interactions between a remnant population of the rufous hare-wallaby,
Lagorchestes hirsutus, and populations of several introduced mammal species in a region of the Tanami
Desert. Transect counts of faecal pellets and tracks were used to determine the local distributions of
all species and analysis of faeces from both predators and competitors of hare-wallabies was undertaken.
Six species of introduced mammals were recorded within the study area: dingoes, rabbits, camels,
foxes, feral cats and cattle. The local distributions for a number of these species were found to be
significantly correlated with that of L. hirsutus during some seasons. Analysis of dingo scats collected
from fire trails within the study area identified a total of 12 different food classes including harewallabies
which occurred in 6.9% of the scats. Foxes and feral cats appear to be more important
predators as demonstrated by their impacts on natural and reintroduced populations of hare-wallabies.
Comparison of the diets of the rabbit and L. hirsutus identified significant overlap in utilised plant
species, particularly during drier times. Competition between rabbits and L. hirsutus seems probable,
given the overlap of their diets and their similar body sizes and metabolic requirements. Cattle and
camels are potentially as important at densities above present levels.
The complex web of interactions between L. hirsutus and these introduced species have important
implications for management of remnant and reintroduced hare-wallaby populations.
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Lundie-Jenkins G, Phillips CM, Jarman PJ. Ecology of the rufous hare-wallaby, Lagorchestes hirsutus Gould (Marsupialia : Macropodidae) in the Tanami Desert, Northern Territory.II Diet and feeding strategy. Wildl Res 1993. [DOI: 10.1071/wr9930477] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The diet preferences and selectivity of the rufous hare-wallaby in the Tanami Desert were examined at
a number of sites and over a number of seasons by microscopic analysis of faecal pellets and direct
observations. Perennial grasses were the most consistent plant items in the diet. Grass seeds were
seasonally important as were the seeds and bulbs of sedges. Species of dicots were also used but most
represented only minor components in the diet. Several species of plant common to the area were
noticeably absent from the diet.
Differences in the diets between four sites of varying floristic composition and fire history were
consistent with differences in vegetation cover at each site. Overall, the absolute proportions and ratios
of monocots and dicots and of leaf and seed portions were strongly similar for all sites, as were
seasonal changes in the proportions of the four main plant categories (monocots, dicots, seeds and
fruits). These changes correlated with local rainfall. Comparisons of plants eaten and plants available
indicate the hare-wallabies' preference for monocots, particularly seed and fruit components. In contrast
consumption of dicots was influericed by the declining quality of other preferred plants. Insects were
seasonally important in the diet and appear to be a potentially important nitrogen supplement during
drier times.
The feeding strategy of the rufous hare-wallaby is flexible and enables it to exploit fully food
resources whose availability is often limited in both time and space. During droughts it seems likely that
the species is food stressed and this could lead to localised declines.
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Morris LF, Phillips CM, Binnie WH, Sander HM, Silverman AK, Menter MA. Oral lesions in patients with psoriasis: a controlled study. Cutis 1992; 49:339-44. [PMID: 1521493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Stomatitis areata migrans was found in 5.4 percent of patients with psoriasis compared to 1 percent of control patients, while benign migratory glossitis was identified in 10.3 percent of patients with psoriasis and 2.5 percent of control patients. The association of these disorders with psoriasis indicates that they may be manifestations of psoriasis of the oral mucosa.
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Affiliation(s)
- L F Morris
- Baylor University Medical Center, Dallas, Texas
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