Kristen M Johansen

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The distribution and morphology of glutamatergic synapses on Drosophila bodywall muscle fibers were examined at the single-synapse level using immunocytochemistry and electrophysiology. We find that glutamate-immunoreactive motor endings innervate the entire larval bodywall musculature, with each muscle fiber receiving at least one glutamatergic ending. The(More)
The primary structure of the major embryonic Notch transcript is presented, as determined by sequence analysis of overlapping cDNA clones. The 10,148 bp sequence corresponding to this transcript possesses an 8109 bp open reading frame that potentially codes for a 2703 amino acid protein. We show that this polypeptide contains a repeated structure composed(More)
We have cloned and characterized JIL-1, a novel tandem kinase in Drosophila that associates with the chromosomes throughout the cell cycle. Antibody staining and live imaging of JIL-1-GFP transgenic flies show that JIL-1 localizes to the gene-rich interband regions of larval polytene chromosomes and is upregulated almost 2-fold on the hypertranscribed male(More)
The Notch gene in Drosophila encodes a transmembrane protein with homology to EGF that appears to mediate cell-cell interactions necessary for proper epidermal vs. neural fate decisions. In this study, we examine Notch expression in detail throughout embryonic and imaginal development using confocal laser-scanning microscopy and specific mAb probes. We find(More)
To analyze the function of the chromosomal kinase JIL-1, we generated an allelic series of hypomorphic and null mutations. JIL-1 is an essential kinase for viability, and reduced levels of JIL-1 kinase activity lead to a global change in chromatin structure. In JIL-1 hypomorphs, euchromatic regions of polytene chromosomes are severely reduced and the(More)
JIL-1 is a novel chromosomal kinase that is upregulated almost twofold on the male X chromosome in Drosophila. Here we demonstrate that JIL-1 colocalizes and physically interacts with male specific lethal (MSL) dosage compensation complex proteins. Furthermore, ectopic expression of the MSL complex directed by MSL2 in females causes a concomitant(More)
A spindle matrix has been proposed to help organize and stabilize the microtubule spindle during mitosis, though molecular evidence corroborating its existence has been elusive. In Drosophila, we have cloned and characterized a novel nuclear protein, skeletor, that we propose is part of a macromolecular complex forming such a spindle matrix. Skeletor(More)
In this study we have generated two new hypomorphic Chro alleles and analyzed the consequences of reduced Chromator protein function on polytene chromosome structure. We show that in Chro(71)/Chro(612) mutants the polytene chromosome arms were coiled and compacted with a disruption and misalignment of band and interband regions and with numerous ectopic(More)
A putative spindle matrix has been hypothesized to mediate chromosome motion, but its existence and functionality remain controversial. In this report, we show that Megator (Mtor), the Drosophila melanogaster counterpart of the human nuclear pore complex protein translocated promoter region (Tpr), and the spindle assembly checkpoint (SAC) protein Mad2 form(More)
We have used a yeast two-hybrid interaction assay to identify Chromator, a novel chromodomain containing protein that interacts directly with the putative spindle matrix protein Skeletor. Immunocytochemistry demonstrated that Chromator and Skeletor show extensive co-localization throughout the cell cycle. During interphase Chromator is localized on(More)