Life Sciences Commons^™

Two Drosophila Suppressors Of Cytokine Signaling (Socs) Differentially Regulate Jak And Egfr Pathway Activities, Jason S. Rawlings, Gabriela Rennebeck, Susan M.W. Harrison, Rongwen Xi, Douglas A. Harrison

Biology Faculty Publications

BACKGROUND: The Janus kinase (JAK) cascade is an essential and well-conserved pathway required to transduce signals for a variety of ligands in both vertebrates and invertebrates. While activation of the pathway is essential to many processes, mutations from mammals and Drosophila demonstrate that regulation is also critical. The SOCS (Suppressor Of Cytokine Signaling) proteins in mammals are regulators of the JAK pathway that participate in a negative feedback loop, as they are transcriptionally activated by JAK signaling. Examination of one Drosophila SOCS homologue, Socs36E, demonstrated that its expression is responsive to JAK pathway activity and it is capable of downregulating …

From Biomedicine To Natural History Research: Est Resources For Ambystomatid Aalamanders, Srikrishna Putta, Jeramiah J. Smith, John A. Walker, Mathieu Rondet, David W. Weisrock, James Monaghan, Amy K. Samuels, D. Kevin Kump, David C. King, Nicholas J. Maness, Bianca Habermann, Elly Tanaka, Susan V. Bryant, David M. Gardiner, David M. Parichy, S. Randal Voss

Biology Faculty Publications

BACKGROUND: Establishing genomic resources for closely related species will provide comparative insights that are crucial for understanding diversity and variability at multiple levels of biological organization. We developed ESTs for Mexican axolotl (Ambystoma mexicanum) and Eastern tiger salamander (A. tigrinum tigrinum), species with deep and diverse research histories.

RESULTS: Approximately 40,000 quality cDNA sequences were isolated for these species from various tissues, including regenerating limb and tail. These sequences and an existing set of 16,030 cDNA sequences for A. mexicanum were processed to yield 35,413 and 20,599 high quality ESTs for A. mexicanum and A. t. tigrinum, respectively. Because the …

Pf15p Is The Chlamydomonas Homologue Of The Katanin P80 Subunit And Is Required For Assembly Of Flagellar Central Microtubules, Erin E. Dymek, Paul A. Lefebvre, Elizabeth F. Smith

Dartmouth Scholarship

Numerous studies have indicated that the central apparatus plays a significant role in regulating flagellar motility, yet little is known about how the central pair of microtubules or their associated projections assemble. Several Chlamydomonas mutants are defective in central apparatus assembly. For example, mutant pf15 cells have paralyzed flagella that completely lack the central pair of microtubules. We have cloned the wild-type PF15 gene and confirmed its identity by rescuing the motility and ultrastructural defects in two pf15 alleles, the original pf15a mutant and a mutant generated by insertional mutagenesis. Database searches using the 798-amino-acid polypeptide predicted from the complete …

Estimating Metazoan Divergence Times With A Molecular Clock, Kevin J. Peterson, Jessica B. Lyons, Kristin S. Nowak, Carter M. Takacs, Matthew J. Wargo, Mark A. Mcpeek

Dartmouth Scholarship

Accurately dating when the first bilaterally symmetrical animals arose is crucial to our understanding of early animal evolution. The earliest unequivocally bilaterian fossils are 555 million years old. In contrast, molecular-clock analyses calibrated by using the fossil record of vertebrates estimate that vertebrates split from dipterans (Drosophila) 900 million years ago (Ma). Nonetheless, comparative genomic analyses suggest that a significant rate difference exists between vertebrates and dipterans, because the percentage difference between the genomes of mosquito and fly is greater than between fish and mouse, even though the vertebrate divergence is almost twice that of the dipteran. Here we show …

The Cohesion Protein Ord Is Required For Homologue Bias During Meiotic Recombination, Hayley A. Webber, Louisa Howard, Sharon E. Bickel

Dartmouth Scholarship

During meiosis, sister chromatid cohesion is required for normal levels of homologous recombination, although how cohesion regulates exchange is not understood. Null mutations in orientation disruptor (ord) ablate arm and centromeric cohesion during Drosophila meiosis and severely reduce homologous crossovers in mutant oocytes. We show that ORD protein localizes along oocyte chromosomes during the stages in which recombination occurs. Although synaptonemal complex (SC) components initially associate with synapsed homologues in ord mutants, their localization is severely disrupted during pachytene progression, and normal tripartite SC is not visible by electron microscopy. In ord germaria, meiotic double strand breaks appear …