Cold Spring Harbor Laboratory

About: Cold Spring Harbor Laboratory is a nonprofit organization based out in Cold Spring Harbor, New York, United States. It is known for research contribution in the topics: Gene & Genome. The organization has 3772 authors who have published 6603 publications receiving 1010873 citations. The organization is also known as: CSHL.

Robertson's Mutator transposons in A. thaliana are regulated by the chromatin-remodeling gene Decrease in DNA Methylation (DDM1)

Abstract: Robertson's Mutator transposable elements in maize undergo cycles of activity and then inactivity that correlate with changes in cytosine methylation. Mutator-like elements are present in the Arabidopsis genome but are heavily methylated and inactive. These elements become demethylated and active in the chromatin-remodeling mutant ddm1 (Decrease in DNA Methylation), which leads to loss of heterochromatic DNA methylation. Thus, DNA transposons in plants appear to be regulated by chromatin remodeling. In inbred ddm1 strains, transposed elements may account, in part, for mutant phenotypes unlinked to ddm1. Gene silencing and paramutation are also regulated by DDM1, providing support for the proposition that epigenetic silencing is related to transposon regulation.

Architecture of floral branch systems in maize and related grasses

Abstract: The external appearance of flowering plants is determined to a large extent by the forms of flower-bearing branch systems, known as inflorescences, and their position in the overall structure of the plant. Branches and branching patterns are produced by tissues called shoot apical meristems. Thus, inflorescence architecture reflects meristem number, arrangement and activity, and the duration of meristem activity correlates with branch length. The inflorescences of maize, unlike those of related grasses such as rice and sorghum, predominantly lack long branches, giving rise to the tassel and familiar corncob. Here we report the isolation of the maize ramosa1 gene and show that it controls inflorescence architecture. Through its expression in a boundary domain near the nascent meristem base, ramosa1 imposes short branch identity as branch meristems are initiated. A second gene, ramosa2, acts through ramosa1 by regulating ramosa1 gene expression levels. ramosa1 encodes a transcription factor that appears to be absent in rice, is heterochronically expressed in sorghum, and may have played an important role in maize domestication and grass evolution.

Genome-wide RNA-mediated interference screen identifies miR-19 targets in Notch-induced T-cell acute lymphoblastic leukaemia

Abstract: MicroRNAs (miRNAs) have emerged as novel cancer genes. In particular, the miR-17-92 cluster, containing six individual miRNAs, is highly expressed in haematopoietic cancers and promotes lymphomagenesis in vivo. Clinical use of these findings hinges on isolating the oncogenic activity within the 17-92 cluster and defining its relevant target genes. Here we show that miR-19 is sufficient to promote leukaemogenesis in Notch1-induced T-cell acute lymphoblastic leukaemia (T-ALL) in vivo. In concord with the pathogenic importance of this interaction in T-ALL, we report a novel translocation that targets the 17-92 cluster and coincides with a second rearrangement that activates Notch1. To identify the miR-19 targets responsible for its oncogenic action, we conducted a large-scale short hairpin RNA screen for genes whose knockdown can phenocopy miR-19. Strikingly, the results of this screen were enriched for miR-19 target genes, and include Bim (Bcl2L11), AMP-activated kinase (Prkaa1) and the phosphatases Pten and PP2A (Ppp2r5e). Hence, an unbiased, functional genomics approach reveals a coordinate clampdown on several regulators of phosphatidylinositol-3-OH kinase-related survival signals by the leukaemogenic miR-19.

Use of polymerase chain reaction epitope tagging for protein tagging in Saccharomyces cerevisiae

Abstract: Epitope tagging is the insertion of a short stretch of amino acids constituting an epitope into another protein. Tagged proteins can be identified by Western, immunoprecipitation and immunofluorescence assays using pre-existing antibodies. We have designed vectors containing the URA3 gene flanked by direct repeats of epitope tags. We use the polymerase chain reaction (PCR) to amplify the tag-URA3-tag cassette such that the ends of the PCR fragments possess homology to the gene of interest. In vivo recombination is then used to direct integration of the fragment to the location of interest, and transformants are selected by their Ura+ phenotype. Finally, selection for Ura- cells on 5-fluoro-orotic acid plates yields cells where recombination between the repeated epitopes has 'popped out' the URA3 gene, leaving a single copy of the epitope at the desired location. PCR epitope tagging (PET) provides a rapid and direct technique for tagging that does not require any cloning steps. We have used PET to tag three Saccharomyces cerevisiae proteins, Cln1, Sic1 and Est1.