Publications by authors named "Cynthia Pfannkoch"

9 Publications

  • Page 1 of 1

The dynamic genome of Hydra.

Nature 2010 Mar 14;464(7288):592-6. Epub 2010 Mar 14.

US Department of Energy Joint Genome Institute, Walnut Creek, California 94598, USA.

The freshwater cnidarian Hydra was first described in 1702 and has been the object of study for 300 years. Experimental studies of Hydra between 1736 and 1744 culminated in the discovery of asexual reproduction of an animal by budding, the first description of regeneration in an animal, and successful transplantation of tissue between animals. Today, Hydra is an important model for studies of axial patterning, stem cell biology and regeneration. Here we report the genome of Hydra magnipapillata and compare it to the genomes of the anthozoan Nematostella vectensis and other animals. The Hydra genome has been shaped by bursts of transposable element expansion, horizontal gene transfer, trans-splicing, and simplification of gene structure and gene content that parallel simplification of the Hydra life cycle. We also report the sequence of the genome of a novel bacterium stably associated with H. magnipapillata. Comparisons of the Hydra genome to the genomes of other animals shed light on the evolution of epithelia, contractile tissues, developmentally regulated transcription factors, the Spemann-Mangold organizer, pluripotency genes and the neuromuscular junction.
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http://dx.doi.org/10.1038/nature08830DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4479502PMC
March 2010

Evolutionary and biomedical insights from the rhesus macaque genome.

Science 2007 Apr;316(5822):222-34

Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA.

The rhesus macaque (Macaca mulatta) is an abundant primate species that diverged from the ancestors of Homo sapiens about 25 million years ago. Because they are genetically and physiologically similar to humans, rhesus monkeys are the most widely used nonhuman primate in basic and applied biomedical research. We determined the genome sequence of an Indian-origin Macaca mulatta female and compared the data with chimpanzees and humans to reveal the structure of ancestral primate genomes and to identify evidence for positive selection and lineage-specific expansions and contractions of gene families. A comparison of sequences from individual animals was used to investigate their underlying genetic diversity. The complete description of the macaque genome blueprint enhances the utility of this animal model for biomedical research and improves our understanding of the basic biology of the species.
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http://dx.doi.org/10.1126/science.1139247DOI Listing
April 2007

Cell-free cloning using phi29 DNA polymerase.

Proc Natl Acad Sci U S A 2005 Nov 14;102(48):17332-6. Epub 2005 Nov 14.

Synthetic Biology Group, The J. Craig Venter Institute, Rockville, MD 20850, USA.

We describe conditions for rolling-circle amplification (RCA) of individual DNA molecules 5-7 kb in size by >10(9)-fold, using phi29 DNA polymerase. The principal difficulty with amplification of small amounts of template by RCA using phi29 DNA polymerase is "background" DNA synthesis that usually occurs when template is omitted, or at low template concentrations. Reducing the reaction volume while keeping the amount of template fixed increases the template concentration, resulting in a suppression of background synthesis. Cell-free cloning of single circular molecules by using phi29 DNA polymerase was achieved by carrying out the amplification reactions in very small volumes, typically 600 nl. This procedure allows cell-free cloning of individual synthetic DNA molecules that cannot be cloned in Escherichia coli, for example synthetic phage genomes carrying lethal mutations. It also allows cell-free cloning of genomic DNA isolated from bacteria. This DNA can be sequenced directly from the phi29 DNA polymerase reaction without further amplification. In contrast to PCR amplification, RCA using phi29 DNA polymerase does not produce mutant jackpots, and the high processivity of the enzyme eliminates stuttering at homopolymer tracts. Cell-free cloning has many potential applications to both natural and synthetic DNA. These include environmental DNA samples that have proven difficult to clone and synthetic genes encoding toxic products. The method may also speed genome sequencing by eliminating the need for biological cloning.
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http://dx.doi.org/10.1073/pnas.0508809102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1283157PMC
November 2005

Environmental genome shotgun sequencing of the Sargasso Sea.

Science 2004 Apr 4;304(5667):66-74. Epub 2004 Mar 4.

Institute for Biological Energy Alternatives, 1901 Research Boulevard, Rockville, MD 20850, USA.

We have applied "whole-genome shotgun sequencing" to microbial populations collected en masse on tangential flow and impact filters from seawater samples collected from the Sargasso Sea near Bermuda. A total of 1.045 billion base pairs of nonredundant sequence was generated, annotated, and analyzed to elucidate the gene content, diversity, and relative abundance of the organisms within these environmental samples. These data are estimated to derive from at least 1800 genomic species based on sequence relatedness, including 148 previously unknown bacterial phylotypes. We have identified over 1.2 million previously unknown genes represented in these samples, including more than 782 new rhodopsin-like photoreceptors. Variation in species present and stoichiometry suggests substantial oceanic microbial diversity.
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http://dx.doi.org/10.1126/science.1093857DOI Listing
April 2004

Genome sequence of the Brown Norway rat yields insights into mammalian evolution.

Nature 2004 Apr;428(6982):493-521

Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, MS BCM226, One Baylor Plaza, Houston, Texas 77030, USA. http://www.hgsc.bcm.tmc.edu

The laboratory rat (Rattus norvegicus) is an indispensable tool in experimental medicine and drug development, having made inestimable contributions to human health. We report here the genome sequence of the Brown Norway (BN) rat strain. The sequence represents a high-quality 'draft' covering over 90% of the genome. The BN rat sequence is the third complete mammalian genome to be deciphered, and three-way comparisons with the human and mouse genomes resolve details of mammalian evolution. This first comprehensive analysis includes genes and proteins and their relation to human disease, repeated sequences, comparative genome-wide studies of mammalian orthologous chromosomal regions and rearrangement breakpoints, reconstruction of ancestral karyotypes and the events leading to existing species, rates of variation, and lineage-specific and lineage-independent evolutionary events such as expansion of gene families, orthology relations and protein evolution.
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http://dx.doi.org/10.1038/nature02426DOI Listing
April 2004

Generating a synthetic genome by whole genome assembly: phiX174 bacteriophage from synthetic oligonucleotides.

Proc Natl Acad Sci U S A 2003 Dec 2;100(26):15440-5. Epub 2003 Dec 2.

Institute for Biological Energy Alternatives, 1901 Research Boulevard, Suite 600, Rockville, MD 20850, USA.

We have improved upon the methodology and dramatically shortened the time required for accurate assembly of 5- to 6-kb segments of DNA from synthetic oligonucleotides. As a test of this methodology, we have established conditions for the rapid (14-day) assembly of the complete infectious genome of bacteriophage X174 (5386 bp) from a single pool of chemically synthesized oligonucleotides. The procedure involves three key steps: (i). gel purification of pooled oligonucleotides to reduce contamination with molecules of incorrect chain length, (ii). ligation of the oligonucleotides under stringent annealing conditions (55 degrees C) to select against annealing of molecules with incorrect sequences, and (iii). assembly of ligation products into full-length genomes by polymerase cycling assembly, a nonexponential reaction in which each terminal oligonucleotide can be extended only once to produce a full-length molecule. We observed a discrete band of full-length assemblies upon gel analysis of the polymerase cycling assembly product, without any PCR amplification. PCR amplification was then used to obtain larger amounts of pure full-length genomes for circularization and infectivity measurements. The synthetic DNA had a lower infectivity than natural DNA, indicating approximately one lethal error per 500 bp. However, fully infectious X174 virions were recovered after electroporation into Escherichia coli. Sequence analysis of several infectious isolates verified the accuracy of these synthetic genomes. One such isolate had exactly the intended sequence. We propose to assemble larger genomes by joining separately assembled 5- to 6-kb segments; approximately 60 such segments would be required for a minimal cellular genome.
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http://dx.doi.org/10.1073/pnas.2237126100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC307586PMC
December 2003

The genome sequence of the malaria mosquito Anopheles gambiae.

Science 2002 Oct;298(5591):129-49

Celera Genomics, 45 West Gude Drive, Rockville, MD 20850, USA.

Anopheles gambiae is the principal vector of malaria, a disease that afflicts more than 500 million people and causes more than 1 million deaths each year. Tenfold shotgun sequence coverage was obtained from the PEST strain of A. gambiae and assembled into scaffolds that span 278 million base pairs. A total of 91% of the genome was organized in 303 scaffolds; the largest scaffold was 23.1 million base pairs. There was substantial genetic variation within this strain, and the apparent existence of two haplotypes of approximately equal frequency ("dual haplotypes") in a substantial fraction of the genome likely reflects the outbred nature of the PEST strain. The sequence produced a conservative inference of more than 400,000 single-nucleotide polymorphisms that showed a markedly bimodal density distribution. Analysis of the genome sequence revealed strong evidence for about 14,000 protein-encoding transcripts. Prominent expansions in specific families of proteins likely involved in cell adhesion and immunity were noted. An expressed sequence tag analysis of genes regulated by blood feeding provided insights into the physiological adaptations of a hematophagous insect.
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http://dx.doi.org/10.1126/science.1076181DOI Listing
October 2002

A comparison of whole-genome shotgun-derived mouse chromosome 16 and the human genome.

Science 2002 May;296(5573):1661-71

Celera Genomics, 45 West Gude Drive, Rockville, MD 20850, USA.

The high degree of similarity between the mouse and human genomes is demonstrated through analysis of the sequence of mouse chromosome 16 (Mmu 16), which was obtained as part of a whole-genome shotgun assembly of the mouse genome. The mouse genome is about 10% smaller than the human genome, owing to a lower repetitive DNA content. Comparison of the structure and protein-coding potential of Mmu 16 with that of the homologous segments of the human genome identifies regions of conserved synteny with human chromosomes (Hsa) 3, 8, 12, 16, 21, and 22. Gene content and order are highly conserved between Mmu 16 and the syntenic blocks of the human genome. Of the 731 predicted genes on Mmu 16, 509 align with orthologs on the corresponding portions of the human genome, 44 are likely paralogous to these genes, and 164 genes have homologs elsewhere in the human genome; there are 14 genes for which we could find no human counterpart.
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http://dx.doi.org/10.1126/science.1069193DOI Listing
May 2002