Bio

Clinical Focus


  • Pediatric Hematology-Oncology

Academic Appointments


Professional Education


  • Residency:Children's Hospital Boston (06/1996) MA
  • Fellowship:Children's Hospital Boston (06/1999) MA
  • Medical Education:Stanford University School of Medicine (06/1994) CA
  • Board Certification: Pediatric Hematology-Oncology, American Board of Pediatrics (2000)

Research & Scholarship

Current Research and Scholarly Interests


Genome Editing and Population Dynamics for Gene Therapy and Cancer Research

Clinical Trials


  • A Multicenter, Open-label Study of CMX001 Treatment of Serious Diseases or Conditions Caused by dsDNA Viruses Not Recruiting

    CMX001 is an orally administered lipid conjugate of the synthetic nucleotide analog cidofovir (CDV). The conjugate is believed to be absorbed in the small intestine then delivered to target organs throughout the body where it crosses cell membranes by facilitated and passive diffusion. Inside the cell, CMX001 is cleaved by intracellular phospholipases to release CDV which is converted to the active antiviral agent, CDV-diphosphate (CDV-PP), by intracellular anabolic kinases. Adults and adolescents, regardless of viral infection/disease, will have a maximum weekly dose of 200 mg i.e., 200 mg once weekly OR 100 mg twice weekly; not to exceed 4mg/kg total weekly dose. Pediatric subjects (< 12 years), regardless of viral infection/disease, will have a maximum weekly dose of 4 mg/kg i.e., 4 mg/kg once weekly OR 2 mg/kg twice weekly.

    Stanford is currently not accepting patients for this trial. For more information, please contact Julia Buckingham, (650) 736 - 1556.

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  • The Adv Halt Trial Not Recruiting

    The primary objective of this study is to evaluate the safety and efficacy of preemptive treatment with CMX001 versus placebo for the prevention of AdV disease in recipients of HSCT with asymptomatic AdV viremia.

    Stanford is currently not accepting patients for this trial. For more information, please contact Julia Buckingham, (650) 736 - 1556.

    View full details

Teaching

2013-14 Courses


Postdoctoral Advisees


Graduate and Fellowship Programs


Publications

Journal Articles


  • An Erythroid Enhancer of BCL11A Subject to Genetic Variation Determines Fetal Hemoglobin Level SCIENCE Bauer, D. E., Kamran, S. C., Lessard, S., Xu, J., Fujiwara, Y., Lin, C., Shao, Z., Canver, M. C., Smith, E. C., Pinello, L., Sabo, P. J., Vierstra, J., Voit, R. A., Yuan, G., Porteus, M. H., Stamatoyannopoulos, J. A., Lettre, G., Orkin, S. H. 2013; 342 (6155): 253-257

    Abstract

    Genome-wide association studies (GWASs) have ascertained numerous trait-associated common genetic variants, frequently localized to regulatory DNA. We found that common genetic variation at BCL11A associated with fetal hemoglobin (HbF) level lies in noncoding sequences decorated by an erythroid enhancer chromatin signature. Fine-mapping uncovers a motif-disrupting common variant associated with reduced transcription factor (TF) binding, modestly diminished BCL11A expression, and elevated HbF. The surrounding sequences function in vivo as a developmental stage-specific, lineage-restricted enhancer. Genome engineering reveals the enhancer is required in erythroid but not B-lymphoid cells for BCL11A expression. These findings illustrate how GWASs may expose functional variants of modest impact within causal elements essential for appropriate gene expression. We propose the GWAS-marked BCL11A enhancer represents an attractive target for therapeutic genome engineering for the ?-hemoglobinopathies.

    View details for DOI 10.1126/science.1242088

    View details for Web of Science ID 000325475200047

    View details for PubMedID 24115442

  • Receptor-mediated delivery of engineered nucleases for genome modification NUCLEIC ACIDS RESEARCH Chen, Z., Jaafar, L., Agyekum, D. G., Xiao, H., Wade, M. F., Kumaran, R. I., Spector, D. L., Bao, G., Porteus, M. H., Dynan, W. S., Meiler, S. E. 2013; 41 (19)

    Abstract

    Engineered nucleases, which incise the genome at predetermined sites, have a number of laboratory and clinical applications. There is, however, a need for better methods for controlled intracellular delivery of nucleases. Here, we demonstrate a method for ligand-mediated delivery of zinc finger nucleases (ZFN) proteins using transferrin receptor-mediated endocytosis. Uptake is rapid and efficient in established mammalian cell lines and in primary cells, including mouse and human hematopoietic stem-progenitor cell populations. In contrast to cDNA expression, ZFN protein levels decline rapidly following internalization, affording better temporal control of nuclease activity. We show that transferrin-mediated ZFN uptake leads to site-specific in situ cleavage of the target locus. Additionally, despite the much shorter duration of ZFN activity, the efficiency of gene correction approaches that seen with cDNA-mediated expression. The approach is flexible and general, with the potential for extension to other targeting ligands and nuclease architectures.

    View details for DOI 10.1093/nar/gkt710

    View details for Web of Science ID 000326044700005

    View details for PubMedID 23956220

  • Newborn screening for severe combined immunodeficiency and T-cell lymphopenia in California: Results of the first 2 years JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY Kwan, A., Church, J. A., Cowan, M. J., Agarwal, R., Kapoor, N., Kohn, D. B., Lewis, D. B., McGhee, S. A., Moore, T. B., Stiehm, E. R., Porteus, M., Aznar, C. P., Currier, R., Lorey, F., Puck, J. M. 2013; 132 (1): 140-U245

    Abstract

    Assay of T-cell receptor excision circles (TRECs) in dried blood spots obtained at birth permits population-based newborn screening (NBS) for severe combined immunodeficiency (SCID).We sought to report the first 2 years of TREC NBS in California.Since August 2010, California has conducted SCID NBS. A high-throughput TREC quantitative PCR assay with DNA isolated from routine dried blood spots was developed. Samples with initial low TREC numbers had repeat DNA isolation with quantitative PCR for TRECs and a genomic control, and immunophenotyping was performed within the screening program for infants with incomplete or abnormal results. Outcomes were tracked.Of 993,724 infants screened, 50 (1/19,900 [0.005%]) had significant T-cell lymphopenia. Fifteen (1/66,250) required hematopoietic cell or thymus transplantation or gene therapy; these infants had typical SCID (n = 11), leaky SCID or Omenn syndrome (n = 3), or complete DiGeorge syndrome (n = 1). Survival to date in this group is 93%. Other T-cell lymphopenic infants had variant SCID or combined immunodeficiency (n = 6), genetic syndromes associated with T-cell impairment (n = 12), secondary T-cell lymphopenia (n = 9), or preterm birth (n = 8). All T-cell lymphopenic infants avoided live vaccines and received appropriate interventions to prevent infections. TREC test specificity was excellent: only 0.08% of infants required a second test, and 0.016% required lymphocyte phenotyping by using flow cytometry.TREC NBS in California has achieved early diagnosis of SCID and other conditions with T-cell lymphopenia, facilitating management and optimizing outcomes. Furthermore, NBS has revealed the incidence, causes, and follow-up of T-cell lymphopenia in a large diverse population.

    View details for DOI 10.1016/j.jaci.2013.04.024

    View details for Web of Science ID 000321052300019

    View details for PubMedID 23810098

  • Generation of an HIV Resistant T-cell Line by Targeted "Stacking" of Restriction Factors MOLECULAR THERAPY Voit, R. A., McMahon, M. A., Sawyer, S. L., Porteus, M. H. 2013; 21 (4): 786-795

    Abstract

    Restriction factors constitute a newly appreciated line of innate immune defense, blocking viral replication inside of infected cells. In contrast to these antiviral proteins, some cellular proteins, such as the CD4, CCR5, and CXCR4 cell surface receptors, facilitate HIV replication. We have used zinc finger nucleases (ZFNs) to insert a cocktail of anti-HIV restriction factors into the CCR5 locus in a T-cell reporter line, knocking out the CCR5 gene in the process. Mirroring the logic of highly active antiretroviral therapy, this strategy provides multiple parallel blocks to infection, dramatically limiting pathways for viral escape, without relying on random integration of transgenes into the genome. Because of the combination of blocks that this strategy creates, our modified T-cell lines are robustly resistant to both CCR5-tropic (R5-tropic) and CXCR4-tropic (X4-tropic) HIV-1. While zinc finger nuclease-mediated CCR5 disruption alone, which mimics the strategy being used in clinical trials, confers 16-fold protection against R5-tropic HIV, it has no effect against X4-tropic virus. Rhesus TRIM5?, chimeric human-rhesus TRIM5?, APOBEC3G D128K, or Rev M10 alone targeted to CCR5 confers significantly improved resistance to infection by both variants compared with CCR5 disruption alone. The combination of three factors targeted to CCR5 blocks infection at multiple stages, providing virtually complete protection against infection by R5-tropic and X4-tropic HIV.

    View details for DOI 10.1038/mt.2012.284

    View details for Web of Science ID 000317110300010

    View details for PubMedID 23358186

  • A Crisper Look at Genome Editing: RNA-guided Genome Modification MOLECULAR THERAPY Damian, M., Porteus, M. H. 2013; 21 (4): 719-721

    View details for DOI 10.1038/mt.2013.46

    View details for Web of Science ID 000317110300002

  • A crisper look at genome editing: RNA-guided genome modification. Molecular therapy : the journal of the American Society of Gene Therapy Damian, M., Porteus, M. H. 2013; 21 (4): 720-722

    View details for DOI 10.1038/mt.2013.46

    View details for PubMedID 23542565

  • A survey of ex vivo/in vitro transduction efficiency of mammalian primary cells and cell lines with Nine natural adeno-associated virus (AAV1-9) and one engineered adeno-associated virus serotype VIROLOGY JOURNAL Ellis, B. L., Hirsch, M. L., Barker, J. C., Connelly, J. P., Steininger, R. J., Porteus, M. H. 2013; 10

    Abstract

    The ability to deliver a gene of interest into a specific cell type is an essential aspect of biomedical research. Viruses can be a useful tool for this delivery, particularly in difficult to transfect cell types. Adeno-associated virus (AAV) is a useful gene transfer vector because of its ability to mediate efficient gene transduction in numerous dividing and quiescent cell types, without inducing any known pathogenicity. There are now a number of natural for that designed AAV serotypes that each has a differential ability to infect a variety of cell types. Although transduction studies have been completed, the bulk of the studies have been done in vivo, and there has never been a comprehensive study of transduction ex vivo/in vitro.Each cell type was infected with each serotype at a multiplicity of infection of 100,000 viral genomes/cell and transduction was analyzed by flow cytometry + .We found that AAV1 and AAV6 have the greatest ability to transduce a wide range of cell types, however, for particular cell types, there are specific serotypes that provide optimal transduction.In this work, we describe the transduction efficiency of ten different AAV serotypes in thirty-four different mammalian cell lines and primary cell types. Although these results may not be universal due to numerous factors such as, culture conditions and/ or cell growth rates and cell heterogeneity, these results provide an important and unique resource for investigators who use AAV as an ex vivo gene delivery vector or who work with cells that are difficult to transfect.

    View details for DOI 10.1186/1743-422X-10-74

    View details for Web of Science ID 000316756700001

    View details for PubMedID 23497173

  • Zinc-finger nuclease-mediated gene correction using single AAV vector transduction and enhancement by Food and Drug Administration-approved drugs GENE THERAPY Ellis, B. L., HIRSCH, M. L., Porter, S. N., Samulski, R. J., Porteus, M. H. 2013; 20 (1): 35-42

    Abstract

    An emerging strategy for the treatment of monogenic diseases uses genetic engineering to precisely correct the mutation(s) at the genome level. Recent advancements in this technology have demonstrated therapeutic levels of gene correction using a zinc-finger nuclease (ZFN)-induced DNA double-strand break in conjunction with an exogenous DNA donor substrate. This strategy requires efficient nucleic acid delivery and among viral vectors, recombinant adeno-associated virus (rAAV) has demonstrated clinical success without pathology. However, a major limitation of rAAV is the small DNA packaging capacity and to date, the use of rAAV for ZFN gene delivery has yet to be reported. Theoretically, an ideal situation is to deliver both ZFNs and the repair substrate in a single vector to avoid inefficient gene targeting and unwanted mutagenesis, both complications of a rAAV co-transduction strategy. Therefore, a rAAV format was generated in which a single polypeptide encodes the ZFN monomers connected by a ribosome skipping 2A peptide and furin cleavage sequence. On the basis of this arrangement, a DNA repair substrate of 750 nucleotides was also included in this vector. Efficient polypeptide processing to discrete ZFNs is demonstrated, as well as the ability of this single vector format to stimulate efficient gene targeting in a human cell line and mouse model derived fibroblasts. Additionally, we increased rAAV-mediated gene correction up to sixfold using a combination of Food and Drug Administration-approved drugs, which act at the level of AAV vector transduction. Collectively, these experiments demonstrate the ability to deliver ZFNs and a repair substrate by a single AAV vector and offer insights for the optimization of rAAV-mediated gene correction using drug therapy.

    View details for DOI 10.1038/gt.2011.211

    View details for Web of Science ID 000313053900005

    View details for PubMedID 22257934

  • Gene therapy for primary immunodeficiencies CURRENT OPINION IN PEDIATRICS Kildebeck, E., Checketts, J., Porteus, M. 2012; 24 (6): 731-738

    Abstract

    Primary immunodeficiencies (PIDs) are an often-devastating class of genetic disorders that can be effectively treated by hematopoietic stem cell transplantation, but the lack of a suitable donor precludes this option for many patients. Gene therapy overcomes this obstacle by restoring gene expression in autologous hematopoietic stem cells and has proven effective in clinical trials, but widespread use of this approach has been impeded by the occurrence of serious complications. In this review, we discuss recent advances in gene therapy with an emphasis on strategies to improve safety, including the emergence of gene targeting technologies for the treatment of PIDs.New viral vectors, including lentiviral vectors with self-inactivating long terminal repeats, have been shown to have improved safety profiles in preclinical studies, and clinical trials using these vectors are now underway. Preclinical studies using engineered nucleases to stimulate precise gene targeting have also demonstrated correction of disease phenotypes for X-linked severe combined immunodeficiency, chronic granulomatous disease, and other diseases.Advances in viral vector design and the development of new technologies that allow precise alteration of the genome have the potential to begin a new chapter for gene therapy where effective treatment of PIDs is achieved without serious risk for patients.

    View details for DOI 10.1097/MOP.0b013e328359e480

    View details for Web of Science ID 000311106800012

    View details for PubMedID 23073463

  • Engineering the immune system to cure genetic diseases, HIV, and cancer Editorial overview CURRENT OPINION IN IMMUNOLOGY Porteus, M. H., Fischer, A. 2012; 24 (5): 576-579

    View details for DOI 10.1016/j.coi.2012.09.004

    View details for Web of Science ID 000319248200011

    View details for PubMedID 23084086

  • Development of nuclease-mediated site-specific genome modification. Current opinion in immunology Wirt, S. E., Porteus, M. H. 2012; 24 (5): 609-616

    Abstract

    Genome engineering is an emerging strategy to treat monogenic diseases that relies on the use of engineered nucleases to correct mutations at the nucleotide level. Zinc finger nucleases can be designed to stimulate homologous recombination-mediated gene targeting at a variety of loci, including genes known to cause the primary immunodeficiencies (PIDs). Recently, these nucleases have been used to correct disease-causing mutations in human cells, as well as to create new animal models for human disease. Although a number of hurdles remain before they can be used clinically, engineered nucleases hold increasing promise as a therapeutic tool, particularly for the PIDs.

    View details for DOI 10.1016/j.coi.2012.08.005

    View details for PubMedID 22981684

  • Gene editing: not just for translation anymore. Nature methods McMahon, M. A., Rahdar, M., Porteus, M. 2012; 9 (1): 28-31

    View details for DOI 10.1038/nmeth.1811

    View details for PubMedID 22205513

  • Viral Single-Strand DNA Induces p53-Dependent Apoptosis in Human Embryonic Stem Cells PLOS ONE Hirsch, M. L., Fagan, B. M., Dumitru, R., Bower, J. J., Yadav, S., Porteus, M. H., Pevny, L. H., Samulski, R. J. 2011; 6 (11)

    Abstract

    Human embryonic stem cells (hESCs) are primed for rapid apoptosis following mild forms of genotoxic stress. A natural form of such cellular stress occurs in response to recombinant adeno-associated virus (rAAV) single-strand DNA genomes, which exploit the host DNA damage response for replication and genome persistence. Herein, we discovered a unique DNA damage response induced by rAAV transduction specific to pluripotent hESCs. Within hours following rAAV transduction, host DNA damage signaling was elicited as measured by increased gamma-H2AX, ser15-p53 phosphorylation, and subsequent p53-dependent transcriptional activation. Nucleotide incorporation assays demonstrated that rAAV transduced cells accumulated in early S-phase followed by the induction of apoptosis. This lethal signaling sequalae required p53 in a manner independent of transcriptional induction of Puma, Bax and Bcl-2 and was not evident in cells differentiated towards a neural lineage. Consistent with a lethal DNA damage response induced upon rAAV transduction of hESCs, empty AAV protein capsids demonstrated no toxicity. In contrast, DNA microinjections demonstrated that the minimal AAV origin of replication and, in particular, a 40 nucleotide G-rich tetrad repeat sequence, was sufficient for hESC apoptosis. Our data support a model in which rAAV transduction of hESCs induces a p53-dependent lethal response that is elicited by a telomeric sequence within the AAV origin of replication.

    View details for DOI 10.1371/journal.pone.0027520

    View details for Web of Science ID 000297555800024

    View details for PubMedID 22114676

  • Seeing the light: integrating genome engineering with double-strand break repair NATURE METHODS Porteus, M. 2011; 8 (8): 628-630

    View details for DOI 10.1038/nmeth.1656

    View details for Web of Science ID 000293220600013

    View details for PubMedID 21799496

  • Translating the Lessons From Gene Therapy to the Development of Regenerative Medicine MOLECULAR THERAPY Porteus, M. 2011; 19 (3): 439-441

    View details for DOI 10.1038/mt.2011.14

    View details for Web of Science ID 000287911600002

    View details for PubMedID 21358706

  • Homologous recombination-based gene therapy for the primary immunodeficiencies YEAR IN HUMAN AND MEDICAL GENETICS: INBORN ERRORS OF IMMUNITY II Porteus, M. 2011; 1246: 131-140

    Abstract

    The devastating nature of primary immunodeficiencies, the ability to cure primary immunodeficiencies by bone marrow transplantation, the ability of a small number of gene-corrected cells to reconstitute the immune system, and the overall suboptimal results of bone marrow transplantation for most patients with primary immunodeficiencies make the development of gene therapy for this class of diseases important. While there has been clear clinical benefit for a number of patients from viral-based gene therapy strategies, there have also been a significant number of serious adverse events, including the development of leukemia, from the approach. In this review, I discuss the development of nuclease-stimulated, homologous recombination-based approaches as a novel gene therapy strategy for the primary immunodeficiencies.

    View details for DOI 10.1111/j.1749-6632.2011.06314.x

    View details for Web of Science ID 000301519900013

    View details for PubMedID 22236437

  • COCCIDIOIDAL ANTIGEN-REACTIVE CD4(+) T-LYMPHOCYTES IN THE CEREBROSPINAL-FLUID IN COCCIDIOIDES-IMMITIS MENINGITIS JOURNAL OF MEDICAL AND VETERINARY MYCOLOGY Vollmer, T. L., Gaiser, C., DELLOCA, R. L., Porteus, M., Steinman, L., Stevens, D. A. 1995; 33 (1): 43-48

    Abstract

    CSF lymphocytes from patients with Coccidioides immitis meningitis exhibited a significant antigen-specific response to in vitro stimulation with C. immitis antigens. In some patients, lesser responses to control antigens (Candida and PPD) were also detected. Antigen-specific responses by CSF lymphocytes were seen early in the course of this disease as well as several years after patients had entered remission. When compared to CSF cells, the response of autologous peripheral blood mononuclear cells was similar but of a much smaller magnitude and at times undetectable. Fluorescence activated cell sorting revealed an increased percentage of CD3+ (T-cells), CD4+ (helper/inducer) and CD3+/HLA-DR+ (activated T-cell) cells in the CSF of C. immitis meningitis patients compared to their blood. Most of the antigen-specific proliferative response resided in the CD4+ lymphocyte subset. CSF T-cell proliferation assays may have a role in the diagnosis of C. immitis meningitis.

    View details for Web of Science ID A1995QZ83200008

    View details for PubMedID 7544405

  • DLX-P, MASH-1, AND MAP-5 EXPRESSION AND BROMODEOXYURIDINE INCORPORATION DEFINE MOLECULARLY DISTINCT CELL-POPULATIONS IN THE EMBRYONIC MOUSE FOREBRAIN JOURNAL OF NEUROSCIENCE Porteus, M. H., Bulfone, A., Liu, J. K., Puelles, L., Lo, L. C., Rubenstein, J. L. 1994; 14 (11): 6370-6383

    Abstract

    Recently, the Dlx family of homeobox genes have been identified as candidates for regulating patterning and differentiation of the forebrain. We have made a polyclonal antiserum to the protein product of the Dlx-2 gene. Using this antiserum, we have characterized the spatial and temporal pattern of DLX-2 protein expression during murine development and in the adult mouse brain. These studies demonstrate that, like the mRNA from the Dlx-2 gene, DLX-2 protein is expressed in mouse embryonic forebrain, limbs, tail, genital tubercle, and branchial arches. Within the embryonic forebrain, DLX-2 protein is expressed within specific transverse and longitudinal domains. Analysis of expression within the wall of the forebrain shows that DLX-2 is expressed in proliferative regions including the ventricular and subventricular zones. DLX-2 is expressed in the same cells as MASH-1, a marker of relatively undifferentiated cells, but in a reciprocal fashion to MAP-2, a marker of terminal neuronal differentiation. A number of DLX-2-expressing cells, but not all, can be labeled with bromodeoxyuridine (BrdU). Using the patterns of DLX-2, MASH-1, MAP-2 expression, and bromodeoxyuridine incorporation, we identify four molecularly distinct populations of cells that may correspond to different stages of neuronal differentiation in the mouse basal forebrain, in which DLX-2 is expressed at the transition from proliferation to terminal differentiation.

    View details for Web of Science ID A1994PQ38100006

    View details for PubMedID 7965042

  • DLX2 (TES1), A HOMEOBOX GENE OF THE DISTAL-LESS FAMILY, ASSIGNED TO CONSERVED REGIONS ON HUMAN AND MOUSE CHROMOSOMES-2 GENOMICS Ozcelik, T., Porteus, M. H., Rubenstein, J. L., FRANCKE, U. 1992; 13 (4): 1157-1161

    Abstract

    Dlx-2 (also called Tes-1), a mammalian member of the Distal-less family of homeobox genes, is expressed during murine fetal development in spatially restricted domains of the forebrain. Searching for a candidate neurological mutation that might involve this gene, we have assigned the human and mouse loci to regions of conserved synteny on human chromosome 2, region cen--q33, and mouse chromosome 2 by Southern analysis of somatic cell hybrid lines. An EcoRI dimorphism, discovered in common inbred laboratory strains, was used for recombinant inbred strain mapping. The results place Dlx-2/Tes-1 near the Hox-4 cluster on mouse chromosome 2.

    View details for Web of Science ID A1992JH14800031

    View details for PubMedID 1354641

  • ISOLATION AND CHARACTERIZATION OF A LIBRARY OF CDNA CLONES THAT ARE PREFERENTIALLY EXPRESSED IN THE EMBRYONIC TELENCEPHALON MOLECULAR BRAIN RESEARCH Porteus, M. H., BRICE, A. E., Bulfone, A., Usdin, T. B., CIARANELLO, R. D., Rubenstein, J. L. 1992; 12 (1-3): 7-22

    Abstract

    In order to isolate genes involved in development of the mammalian telencephalon we employed an efficient cDNA library procedure. By subtracting an adult mouse telencephalic cDNA library from an embryonic day 15 (E15) mouse telencephalic cDNA library we generated two subtracted libraries (ES1 and ES2). We estimate that ES1 contains between 200 and 600 different cDNA clones, which approximates the number of genes that are preferentially expressed in the E15 telencephalon, compared to the adult telencephalon. Northern analysis of 20 different cDNA clones shows that 14 of these are expressed at least 5-fold more in the E15 telencephalon than the adult telencephalon. Limited sequencing of the 14 differentially expressed clones reveals that 10 have no significant identity to sequences in GenBank and EMBL databases, whereas the other 4 have significant sequence identity to vimentin, histone 3.3, topoisomerase I and the B2 repeat element. In situ hybridization using one of the differentially expressed cDNAs, TES-1, demonstrates that it is transiently expressed in the anlage of the basal ganglia. In situ hybridization with another differentially expressed cDNA clone, TES-4, shows that it is specifically expressed in differentiating cells of the neural axis with a distinctive rostral-caudal temporal pattern. These findings, and the methods that we have developed, provide a framework for future investigations of the genetic control of telencephalon development.

    View details for Web of Science ID A1992GZ10000002

    View details for PubMedID 1372074

  • ISOLATION AND CHARACTERIZATION OF A NOVEL CDNA CLONE ENCODING A HOMEODOMAIN THAT IS DEVELOPMENTALLY REGULATED IN THE VENTRAL FOREBRAIN NEURON Porteus, M. H., Bulfone, A., CIARANELLO, R. D., Rubenstein, J. L. 1991; 7 (2): 221-229

    Abstract

    A complementary DNA, Tes-1, of a novel homeodomain protein has been cloned, and its pattern of expression has been characterized. It is a structural homolog of Distal-less, a homeodomain-encoding gene in D. melanogaster. Its expression is developmentally regulated and is limited to structures in the head. Within the central nervous system of the midgestation mouse embryo, it is expressed exclusively in the ventral forebrain. It is likely that Tes-1 plays a regulatory role in the development of this complex neural structure.

    View details for Web of Science ID A1991GB93300005

    View details for PubMedID 1678612

  • SUBTRACTIVE HYBRIDIZATION SYSTEM USING SINGLE-STRANDED PHAGEMIDS WITH DIRECTIONAL INSERTS NUCLEIC ACIDS RESEARCH Rubenstein, J. L., BRICE, A. E., CIARANELLO, R. D., Denney, D., Porteus, M. H., Usdin, T. B. 1990; 18 (16): 4833-4842

    Abstract

    We describe a subtractive hybridization protocol which is designed to permit subtractions between cDNA libraries. The method uses single-stranded phagemids with directional inserts as both the driver and the target. We modified the M13 phagemid vector pBluescript for the directional cDNA cloning and subtractive hybridization. Two simplified methods for efficient construction of directional cDNA libraries are also described. Using a model system, we found that one round of subtractive hybridization results in a 5,000-fold specific subtraction of abundant molecules. We used two methods to quantify the efficiency and verify the specificity of the subtraction. In order to obtain these subtraction efficiencies, it was necessary to develop a method to purify the single-stranded DNA to homogeneity. The single-stranded purification involved using potassium iodide (KI) density centrifugation, restriction endonuclease digestion and phenol extraction in the presence of magnesium. We describe the several advantages of using directional inserts for the subtraction procedure.

    View details for Web of Science ID A1990DX66200027

    View details for PubMedID 2168539

  • VALIDATION OF A MODEL OF NON-RHEGMATOGENOUS RETINAL-DETACHMENT CURRENT EYE RESEARCH Marmor, M. F., Porteus, M., Negi, A., Immel, J. 1984; 3 (3): 515-518

    Abstract

    To study the movement of subretinal fluid, we have injected fluid into the subretinal space through a glass micropipette and monitored its resorption. This technique has been criticized as a model of non-rhegmatogenous detachment because the small retinal hole made by the micropipette might allow efflux of subretinal fluid into the vitreous. The present experiments answer this criticism: we found that sealing the micropipette hole with cyanoacrylate, mucilage or an air bubble had no effect on the rate of subretinal fluid resorption, and detachments with two to five micropipette holes did not resorb faster than those with only one.

    View details for Web of Science ID A1984SC67800016

    View details for PubMedID 6697753

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