Genetics Commons^™

Homocysteine Thiolactone From Translation Proofreading Is An Endogenous Ligand For Cell-Cell Signaling By The Receptor Sdia, Lorenzo Eugenio Leiva, Roberto A. Zúñiga, Gregory J. Phillips, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Several widespread mechanisms enable cellular communication and coordinate the behavior of bacterial populations. The modules responsible for cellular communication are often found in matching pairs: an enzyme that synthesizes a signal molecule and a specific receptor that decodes it. A notable exception is Escherichia coli SdiA, a homolog of known N-acyl-homoserine lactone (AHL) receptors, for which no corresponding AHL synthase exists. SdiA is an orphan receptor that enables cross-talk by sensing AHLs from other bacterial species. In this work, we investigated whether homocysteine thiolactone (HTL), an AHL-like molecule arising from a proofreading reaction of methionyl tRNA synthetase (MetRS) to correct …

Mobile Genetic Elements Shape Microbial Diversity And Functions In Thawing Permafrost Soils, Jiarong Guo, Samuel T. N. Aroney, Guillermo Domínguez-Huerta, Derek Smith, Dean Vik, Carlos Owusu-Ansah, Akbar Adjie Pratama, Sergei Solonenko, Funing Tian, Cristina Howard-Varona, Zhi-Ping Zhong, Aminata Fofana, Garrett J. Smith, Suzanne B. Hodgkins, Dylan Cronin, Isogenie Field Teams 2010–2017, 2019, Emerge Coordinators, Ben J. Woodcroft, Gene W. Tyson, Virginia I. Rich, Matthew B. Sullivan, Simon Roux, Sarah C. Bagby, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Ecosystems are shaped by communities of microorganisms whose niches and impacts depend on functional profiles influenced by gene gains and losses. Culture-based experiments demonstrate that mobile genetic elements (MGEs) can mediate gene flux, but quantitative understanding of these dynamics in natural systems remains limited. Here we develop and apply a systematic, meta-omic framework to investigate MGEs in a complex natural system using an 8-year soil time series collected at Stordalen Mire, in Sweden’s thawing permafrost margin. In this climate-critical peatland, we identify ~2.1 million MGE recombinases across 89 microbial phyla and assess ecological distributions, affected functions, past mobility and current …

The Competition Between Splicing And 3′ Processing Shapes The Human Transcriptome, Lindsey V. Soles, Shuangyu Li, Liang Liu, Kristianna S.K. Sarkan, Erik G. Alvstad, Lusong Tian, Yoseop Yoon, Marielle Valdez, Ivan Marazzi, Yongsheng Shi

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Eukaryotic pre-mRNA processing steps, including splicing and 3′ processing, are tightly coordinated, yet the underlying mechanisms remain incompletely understood. U1 snRNP has been proposed to inhibit 3′ processing at intronic polyadenylation (IPA) sites through a splicing-independent mechanism termed telescripting. In contrast, we discovered that disrupting splicing by using six different methods—targeting various key components such as U1 snRNP, U2 snRNP, U2AF, and SF3b—activates 3′ processing at thousands of IPA sites. Notably, splicing inhibition, especially of U1 snRNP, induced widespread premature transcription termination within gene bodies through both IPA-coupled and IPA-independent mechanisms. Inhibition of different splicing factors activated overlapping and distinct …

Variation In Thermal Tolerance Plasticity And The Costs Of Heat Exposure In The Estuarine Sea Hare, Phyllaplysia Taylori, Richelle L. Tanner, Rauri C. K. Bowie, Cynthia Y. Wang-Claypool, Jonathan H. Stillman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Climate change is increasing average temperatures and the frequency and intensity of thermal extremes in coastal marine environments. Organisms in coastal marine habitats are accustomed to environmental fluctuations and possess physiological plasticity that may be advantageous in response to increased occurrence of extremes. To examine whether such plasticity is locally adapted to environmental conditions, we investigated the relationship between genetic diversity and thermal tolerance plasticity in 11 populations of the direct-developing intertidal sea hare, Phyllaplysia taylori, on the western coast of the United States. Using whole-organism metrics of muscle function and metabolic rate and a ddRADseq genomic approach, we …

Aars Online: A Collaborative Database On The Structure, Function, And Evolution Of The Aminoacyl-Trna Synthetases, Jordan Douglas, Haissi Cui, John J. Perona, Oscar Vargas-Rodriguez, Henna Tyynismaa, Claudia Alvarez Carreño, Jiqiang Ling, Lluís Ribas De Pouplana, Xiang-Lei Yang, Michael Ibba, Hubert Becker, Frédéric Fischer, Marie Sissler, Charles W. Carter Jr., Peter Wills

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The aminoacyl-tRNA synthetases (aaRS) are a large group of enzymes that implement the genetic code in all known biological systems. They attach amino acids to their cognate tRNAs, moonlight in various translational and non-translational activities beyond aminoacylation, and are linked to many genetic disorders. The aaRS have a subtle ontology characterized by structural and functional idiosyncrasies that vary from organism to organism, and protein to protein. Across the tree of life, the 22 coded amino acids are handled by 16 evolutionary families of Class I aaRS and 21 families of Class II aaRS. We introduce AARS Online, an interactive Wikipedia-like …

Stress Granule Formation Helps To Mitigate Neurodegeneration, M. Rebecca Glineburg, Evrim Yildirim, Nicolas Gomez, Genesis Rodriguez, Jaclyn Pak, Xingli Li, Christopher Altheim, Jacob Waksmacki, Gerald M. Mcinerney, Sami J. Barmada, Peter K. Todd

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Cellular stress pathways that inhibit translation initiation lead to transient formation of cytoplasmic RNA/protein complexes known as stress granules. Many of the proteins found within stress granules and the dynamics of stress granule formation and dissolution are implicated in neurodegenerative disease. Whether stress granule formation is protective or harmful in neurodegenerative conditions is not known. To address this, we took advantage of the alphavirus protein nsP3, which selectively binds dimers of the central stress granule nucleator protein G3BP and markedly reduces stress granule formation without directly impacting the protein translational inhibitory pathways that trigger stress granule formation. In Drosophila and …

Multiple Light Signaling Pathways Control Solar Tracking In Sunflowers, Christopher J. Brooks, Hagop S. Atamian, Stacey L. Harmer

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Sunflowers are famous for their ability to track the sun throughout the day and then reorient at night to face east the following morning. This occurs by differential growth patterns, with the east sides of stems growing more during the day and the west sides of stems growing more at night. This process, termed heliotropism, is generally believed to be a specialized form of phototropism; however, the underlying mechanism is unknown. To better understand heliotropism, we compared gene expression patterns in plants undergoing phototropism in a controlled environment and in plants initiating and maintaining heliotropic growth in the field. We …

Physiological And Transcriptomic Responses Of Two Artemisia Californica Populations To Drought: Implications For Restoring Drought-Resilient Native Communities, Hagop S. Atamian Dr., Jennifer L. Funk

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

As climate change brings drier and more variable rainfall patterns to many arid and semi-arid regions, land managers must re-assemble appropriate plant communities for these conditions. Transcriptome sequencing can elucidate the molecular mechanisms underlying plant responses to changing environmental conditions, potentially enhancing our ability to screen suitable genotypes and species for restoration. We examined physiological and morphological traits and transcriptome sequences of coastal and inland populations of California sagebrush (Artemisia californica), a critical shrub used to restore coastal sage scrub vegetation communities, grown under low and high rainfall environments. The populations are located approximately 36 km apart but …

The Effect Of Infection Risk On Female Blood Transcriptomics, Brenna M. G. Gormally, Patricia C. Lopes

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Defenses against pathogens can take on many forms. For instance, behavioral avoidance of diseased conspecifics is widely documented. Interactions with these infectious conspecifics can also, however, lead to physiological changes in uninfected animals, an effect that is much less well understood. These changes in behavior and physiology are particularly important to study in a reproductive context, where they can impact reproductive decisions and offspring quality. Here, we studied how an acute (3 h) exposure to an immune-challenged male affected female blood transcriptomics and behavior. We predicted that females paired with immune-challenged males would reduce eating and drinking behaviors (as avoidance …

Escherichia Coli Alanyl-Trna Synthetase Maintains Proofreading Activity And Translational Accuracy Under Oxidative Stress, Arundhati Kavoor, Paul Kelly, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Aminoacyl-tRNA synthetases (aaRSs) are enzymes that synthesize aminoacyl-tRNAs to facilitate translation of the genetic code. Quality control by aaRS proofreading and other mechanisms maintains translational accuracy, which promotes cellular viability. Systematic disruption of proofreading, as recently demonstrated for alanyl-tRNA synthetase (AlaRS), leads to dysregulation of the proteome and reduced viability. Recent studies showed that environmental challenges such as exposure to reactive oxygen species can also alter aaRS synthetic and proofreading functions, prompting us to investigate if oxidation might positively or negatively affect AlaRS activity. We found that while oxidation leads to modification of several residues in Escherichia coli AlaRS, unlike …

Induction Of Il19 Expression Through Jnk And Cgas-Sting Modulates Dna Damage–Induced Cytokine Production, Sara H. Small, E. Jessica Tang, Ryan L. Ragland, Yaroslava Ruzankina, David W. Schoppy, Rahul S. Mandal, M. Rebecca Glineburg, Zgjim Ustelenca, Daniel J. Powell, Fiona Simpkins, F. Bradley Johnson, Eric J. Brown

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Cytokine production is a critical component of cell-extrinsic responses to DNA damage and cellular senescence. Here, we demonstrated that expression of the gene encoding interleukin-19 (IL-19) was enhanced by DNA damage through pathways mediated by c-Jun amino-terminal kinase (JNK) and cGAS-STING and that IL19 expression was required for the subsequent production of the cytokines IL-1, IL-6, and IL-8. IL19 expression was stimulated by diverse cellular stresses, including inhibition of the DNA replication checkpoint kinase ATR (ataxia telangiectasia and Rad3-related protein), oncogene expression, replicative exhaustion, oxidative stress, and DNA double-strand breaks. Unlike the production of IL-6 and IL-8, IL19 expression was …

Role Of A Cryptic Trna Gene Operon In Survival Under Translational Stress, Javier Santamaría-Gómez, Miguel Ángel Rubio, Rocío López-Igual, Ana B. Romero-Losada, Fernando M. Delgado-Chaves, Roque Bru-Martínez, Francisco J. Romero-Campero, Antonio Herrero, Michael Ibba, Jesús A. G. Ochoa De Alda, Ignacio Luque

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

As compared to eukaryotes, bacteria have a reduced tRNA gene set encoding between 30 and 220 tRNAs. Although in most bacterial phyla tRNA genes are dispersed in the genome, many species from distinct phyla also show genes forming arrays. Here, we show that two types of arrays with distinct evolutionary origins exist. This work focuses on long tRNA gene arrays (L-arrays) that encompass up to 43 genes, which disseminate by horizontal gene transfer and contribute supernumerary tRNA genes to the host. Although in the few cases previously studied these arrays were reported to be poorly transcribed, here we show that …

Wild Mice With Different Social Network Sizes Vary In Brain Gene Expression, Patricia C. Lopes, Barbara König

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Background

Appropriate social interactions influence animal fitness by impacting several processes, such as mating, territory defense, and offspring care. Many studies shedding light on the neurobiological underpinnings of social behavior have focused on nonapeptides (vasopressin, oxytocin, and homologues) and on sexual or parent-offspring interactions. Furthermore, animals have been studied under artificial laboratory conditions, where the consequences of behavioral responses may not be as critical as when expressed under natural environments, therefore obscuring certain physiological responses. We used automated recording of social interactions of wild house mice outside of the breeding season to detect individuals at both tails of a distribution …

De Novo Sequencing And Analysis Of Salvia Hispanica Tissue-Specific Transcriptome And Identification Of Genes Involved In Terpenoid Biosynthesis, James Wimberley, Joseph Cahill, Hagop S. Atamian

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Salvia hispanica (commonly known as chia) is gaining popularity worldwide as a healthy food supplement due to its low saturated fatty acid and high polyunsaturated fatty acid content, in addition to being rich in protein, fiber, and antioxidants. Chia leaves contain plethora of secondary metabolites with medicinal properties. In this study, we sequenced chia leaf and root transcriptomes using the Illumina platform. The short reads were assembled into contigs using the Trinity software and annotated against the Uniprot database. The reads were de novo assembled into 103,367 contigs, which represented 92.8% transcriptome completeness and a diverse set of Gene Ontology …

A "Choose-Your-Own" Classroom-Based Activity That Promotes Scientific Inquiry About Rna Interference, Jeremy L. Hsu

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

RNA interference (RNAi), the process that results in the degradation of a target gene’s mRNA, is a fundamental part of eukaryotic gene regulation and is also an important molecular technique that allows for experimental manipulation of gene expression without altering DNA sequences. Despite the importance of RNAi, there have been relatively few lecture-based activities designed to teach about the consequences of this process and counter common misconceptions. I present here an inquiry-based activity that is centered around a “choose your own experiment” design where students generate hypotheses and critically evaluate their ideas by choosing several simulated experiments. The activity presents …

Deletion Of Uls1 Confers Damage Tolerance In Sgs1 Mutants Through A Top3-Dependent D-Loop Mediated Fork Restart Pathway, M. Rebecca Glineburg, Eleanor Johns, F. Brad Johnson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Homologous recombination (HR)-based repair during DNA replication can apparently utilize several partially overlapping repair pathways in response to any given lesion. A key player in HR repair is the Sgs1-Top3-Rmi1 (STR) complex, which is critical for resolving X-shaped recombination intermediates formed following bypass of methyl methanesulfonate (MMS)-induced damage. STR mutants are also sensitive to the ribonucleotide reductase inhibitor, hydroxyurea (HU), but unlike MMS treatment, HU treatment is not accompanied by X-structure accumulation, and it is thus unclear how STR functions in this context. Here we provide evidence that HU-induced fork stalling enlists Top3 prior to recombination intermediate formation. The resistance …

Composition Of The Survival Motor Neuron (Smn) Complex In Drosophila Melanogaster, A. Gregory Matera, Amanda C. Raimer, Casey A. Schmidt, Jo A. Kelly, Gaith N. Droby, David Baillat, Sara Ten Have, Angus I. Lamond, Eric J. Wagner, Kelsey M. Gray

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Spinal Muscular Atrophy (SMA) is caused by homozygous mutations in the human survival motor neuron 1 (SMN1) gene. SMN protein has a well-characterized role in the biogenesis of small nuclear ribonucleoproteins (snRNPs), core components of the spliceosome. SMN is part of an oligomeric complex with core binding partners, collectively called Gemins. Biochemical and cell biological studies demonstrate that certain Gemins are required for proper snRNP assembly and transport. However, the precise functions of most Gemins are unknown. To gain a deeper understanding of the SMN complex in the context of metazoan evolution, we investigated its composition in Drosophila …

Hnrnpa2 Mediated Acetylation Reduces Telomere Length In Response To Mitochondrial Dysfunction, Manti Guha, Satish Srinivasan, F. Bradley Johnson, Gordon Ruthel, Kip Guja, Miguel Garcia-Diaz, Brett A. Kaufman, M. Rebecca Glineburg, Jikang Fang, Hiroshi Nakagawa, Jeelan Basha, Tapas Kundu, Narayan G. Avadhani

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Telomeres protect against chromosomal damage. Accelerated telomere loss has been associated with premature aging syndromes such as Werner’s syndrome and Dyskeratosis Congenita, while, progressive telomere loss activates a DNA damage response leading to chromosomal instability, typically observed in cancer cells and senescent cells. Therefore, identifying mechanisms of telomere length maintenance is critical for understanding human pathologies. In this paper we demonstrate that mitochondrial dysfunction plays a causal role in telomere shortening. Furthermore, hnRNPA2, a mitochondrial stress responsive lysine acetyltransferase (KAT) acetylates telomere histone H4at lysine 8 of (H4K8) and this acetylation is associated with telomere attrition. Cells containing dysfunctional mitochondria …

Self-Oligomerization Regulates Stability Of Survival Motor Neuron Protein Isoforms By Sequestering An ScfSlmb Degron, Kelsey M. Gray, Kevin A. Kaifer, David Baillat, Ying Wen, Thomas R. Bonacci, Allison D. Ebert, Amanda C. Raimer, Ashlyn M. Spring, Sara Ten Have, Jacqueline J. Glascock, Kushol Gupta, Gregory D. Van Duyne, Michael J. Emanuele, Angus I. Lamond, Eric J. Wagner, Christian L. Lorson, A. Gregory Matera

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Spinal muscular atrophy (SMA) is caused by homozygous mutations in human SMN1. Expression of a duplicate gene (SMN2) primarily results in skipping of exon 7 and production of an unstable protein isoform, SMNΔ7. Although SMN2 exon skipping is the principal contributor to SMA severity, mechanisms governing stability of survival motor neuron (SMN) isoforms are poorly understood. We used a Drosophila model system and label-free proteomics to identify the SCF^Slmb ubiquitin E3 ligase complex as a novel SMN binding partner. SCF^Slmb interacts with a phosphor degron embedded within the human and fruitfly SMN YG-box oligomerization domains. …

Repeat-Associated Non-Aug (Ran) Translation And Other Molecular Mechanisms In Fragile X Tremor Ataxia Syndrome, M. Rebecca Glineburg, Peter K. Todd, Nicolas Charlet-Berguerand, Chantal Sellier

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset inherited neurodegenerative disorder characterized by progressive intention tremor, gait ataxia and dementia associated with mild brain atrophy. The cause of FXTAS is a premutation expansion, of 55 to 200 CGG repeats localized within the 5′UTR of FMR1. These repeats are transcribed in the sense and antisense directions into mutants RNAs, which have increased expression in FXTAS. Furthermore, CGG sense and CCG antisense expanded repeats are translated into novel proteins despite their localization in putatively non-coding regions of the transcript. Here we focus on two proposed disease mechanisms for FXTAS: 1) RNA …

Ran Translation At C9orf72-Associated Repeat Expansions Is Selectively Enhanced By The Integrated Stress Response, Katelyn M. Green, M. Rebecca Glineburg, Michael G. Kearse, Brittany N. Flores, Alexander E. Linsalata, Stephen J. Fedak, Aaron C. Goldstrohm, Sami J. Barmada, Peter K. Todd

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Repeat-associated non-AUG (RAN) translation allows for unconventional initiation at disease-causing repeat expansions. As RAN translation contributes to pathogenesis in multiple neurodegenerative disorders, determining its mechanistic underpinnings may inform therapeutic development. Here we analyze RAN translation at G₄C₂ repeat expansions that cause C9orf72-associated amyotrophic lateral sclerosis and frontotemporal dementia (C9RAN) and at CGG repeats that cause fragile X-associated tremor/ataxia syndrome. We find that C9RAN translation initiates through a cap- and eIF4A-dependent mechanism that utilizes a CUG start codon. C9RAN and CGG RAN are both selectively enhanced by integrated stress response (ISR) activation. ISR-enhanced RAN translation requires an …

Genomic Data Reveal A Loss Of Diversity In Two Species Of Tuco-Tucos (Genus Ctenomys) Following A Volcanic Eruption, Jeremy L. Hsu, Jeremy Chase Crawford, Mauro N. Tammone, Uma Ramakrishnan, Eileen A. Lacey, Elizabeth A. Hadly

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Marked reductions in population size can trigger corresponding declines in genetic variation. Understanding the precise genetic consequences of such reductions, however, is often challenging due to the absence of robust pre- and post-reduction datasets. Here, we use heterochronous genomic data from samples obtained before and immediately after the 2011 eruption of the Puyehue-Cordón Caulle volcanic complex in Patagonia to explore the genetic impacts of this event on two parapatric species of rodents, the colonial tuco-tuco (Ctenomys sociabilis) and the Patagonian tuco-tuco (C. haigi). Previous analyses using microsatellites revealed no post-eruption changes in genetic variation in C. …

Rapid Increase In Genetic Diversity In An Endemic Patagonian Tuco-Tuco Following A Recent Volcanic Eruption, Jeremy L. Hsu, Sharon Kam, Mauro N. Tammone, Eileen A. Lacey, Elizabeth A. Hadly

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Catastrophic natural events can have profound impacts on patterns of genetic diversity. Due to the typically unpredictable nature of such phenomena, however, few studies have been able to directly compare patterns of diversity before and after natural catastrophic events. Here, we examine the impacts of a recent volcanic eruption in southern Chile on genetic variation in the colonial tuco-tuco (Ctenomys sociabilis), a subterranean species of rodent endemic to the area most affected by the June 2011 eruption of the Puyehue-Cordón Caulle volcanic complex. To provide a comparative context for interpreting changes in genetic variation in this species, we …

Hnrnpa2 Is A Novel Histone Acetyltransferase That Mediates Mitochondrial Stress-Induced Nuclear Gene Expression, Manti Guha, Satish Srinivasan, Kip Guja, Edison Mejia, Miguel Garcia-Diaz, F. Brad Johnson, Gordon Ruthel, Brett A. Kaufman, Eric F. Rappaport, M. Rebecca Glineburg, Ji-Kang Fang, Andres J. Klein-Szanto, Hiroshi Nakagawa, Jeelan Basha, Tapas Kundu, Narayan G. Avadhani

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Reduced mitochondrial DNA copy number, mitochondrial DNA mutations or disruption of electron transfer chain complexes induce mitochondria-to-nucleus retrograde signaling, which induces global change in nuclear gene expression ultimately contributing to various human pathologies including cancer. Recent studies suggest that these mitochondrial changes cause transcriptional reprogramming of nuclear genes although the mechanism of this cross talk remains unclear. Here, we provide evidence that mitochondria-to-nucleus retrograde signaling regulates chromatin acetylation and alters nuclear gene expression through the heterogeneous ribonucleoprotein A2 (hnRNAP2). These processes are reversed when mitochondrial DNA content is restored to near normal cell levels. We show that the mitochondrial stress-induced …

The Genetic Ancestry Of African Americans, Latinos, And European Americans Across The United States, Katarzyna Bryc, Eric Y. Durand, J. Michael Macpherson, David Reich, Joanna Mountain

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Over the past 500 years, North America has been the site of ongoing mixing of Native Americans, European settlers, and Africans (brought largely by the trans-Atlantic slave trade), shaping the early history of what became the United States. We studied the genetic ancestry of 5,269 self-described African Americans, 8,663 Latinos, and 148,789 European Americans who are 23andMe customers and show that the legacy of these historical interactions is visible in the genetic ancestry of present-day Americans. We document pervasive mixed ancestry and asymmetrical male and female ancestry contributions in all groups studied. We show that regional ancestry differences reflect historical …

Sma-Causing Missense Mutations In Survival Motor Neuron (Smn) Display A Wide Range Of Phenotypes When Modeled In Drosophila, Kavita Praveen, Ying Wen, Kelsey M. Gray, John J. Noto, Akash R. Patlolla, Gregory D. Van Duyne, A. Gregory Matera

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Mutations in the human survival motor neuron 1 (SMN) gene are the primary cause of spinal muscular atrophy (SMA), a devastating neuromuscular disorder. SMN protein has a well-characterized role in the biogenesis of small nuclear ribonucleoproteins (snRNPs), core components of the spliceosome. Additional tissue-specific and global functions have been ascribed to SMN; however, their relevance to SMA pathology is poorly understood and controversial. Using Drosophila as a model system, we created an allelic series of twelve Smn missense mutations, originally identified in human SMA patients. We show that animals expressing these SMA-causing mutations display a broad range of …

Resolution By Unassisted Top3 Points To Template Switch Recombination Intermediates During Dna Replication, M. Rebecca Glineburg, Alejandro Chavez, Vishesh Agrawal, Steven J. Brill, F. Brad Johnson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The evolutionarily conserved Sgs1/Top3/Rmi1 (STR) complex plays vital roles in DNA replication and repair. One crucial activity of the complex is dissolution of toxic X-shaped recombination intermediates that accumulate during replication of damaged DNA. However, despite several years of study the nature of these X-shaped molecules remains debated. Here we use genetic approaches and two-dimensional gel electrophoresis of genomic DNA to show that Top3, unassisted by Sgs1 and Rmi1, has modest capacities to provide resistance to MMS and to resolve recombination-dependent X-shaped molecules. The X-shaped molecules have structural properties consistent with hemicatenane-related template switch recombination intermediates (Rec-Xs) but not Holliday …

Cryptic Distant Relatives Are Common In Both Isolated And Cosmopolitan Genetic Samples, Brenna M. Henn, Lawrence S. Hon, J. Michael Macpherson, Nicholas Eriksson, Serge Saxonov, Itsik Pe'er, Joanna Mountain

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Although a few hundred single nucleotide polymorphisms (SNPs) suffice to infer close familial relationships, high density genome-wide SNP data make possible the inference of more distant relationships such as 2nd to 9th cousinships. In order to characterize the relationship between genetic similarity and degree of kinship given a timeframe of 100–300 years, we analyzed the sharing of DNA inferred to be identical by descent (IBD) in a subset of individuals from the 23andMe customer database (n = 22,757) and from the Human Genome Diversity Panel (HGDP-CEPH, n = 952). With data from 121 populations, we show that the average amount …

Efficient Replication Of Over 180 Genetic Associations With Self-Reported Medical Data, Joyce Y. Tung, Chuong B. Do, David A. Hinds, Amy K. Kiefer, J. Michael Macpherson, Arnab B. Chowdry, Uta Francke, Brian Naughton, Joanna Mountain, Anne Wojcicki, Nicholas Eriksson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

While the cost and speed of generating genomic data have come down dramatically in recent years, the slow pace of collecting medical data for large cohorts continues to hamper genetic research. Here we evaluate a novel online framework for obtaining large amounts of medical information from a recontactable cohort by assessing our ability to replicate genetic associations using these data. Using web-based questionnaires, we gathered self-reported data on 50 medical phenotypes from a generally unselected cohort of over 20,000 genotyped individuals. Of a list of genetic associations curated by NHGRI, we successfully replicated about 75% of the associations that we …

Web-Based, Participant-Driven Studies Yield Novel Genetic Associations For Common Traits, Nicholas Eriksson, J. Michael Macpherson, Joyce Y. Tung, Lawrence S. Hon, Brian Naughton, Serge Saxonov, Linda Avey, Anne Wojcicki, Itsik Pe'er, Joanna Mountain

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Despite the recent rapid growth in genome-wide data, much of human variation remains entirely unexplained. A significant challenge in the pursuit of the genetic basis for variation in common human traits is the efficient, coordinated collection of genotype and phenotype data. We have developed a novel research framework that facilitates the parallel study of a wide assortment of traits within a single cohort. The approach takes advantage of the interactivity of the Web both to gather data and to present genetic information to research participants, while taking care to correct for the population structure inherent to this study design. Here …