100,339 research outputs found
Identification and characterisation of synaptonemal complex genes in monotremes
No full textAbstract not availableAaron E. Casey, Tasman J. Daish, Frank Grutzne
Location, Location, Location! Monotremes Provide Unique Insights into the Evolution of Sex Chromosome Silencing in Mammals
No full textCopyright © Mary Ann Liebert, Inc.Platypus and echidnas are the only living representative of the egg-laying mammals that diverged 166 million years ago from the mammalian lineage. Despite occupying a key spot in mammalian phylogeny, research on monotremes has been limited by access to material and lack of molecular genetic resources. This has changed recently, and the sequencing of the platypus genome has promoted monotremes into a generally accessible tool in comparative genomics. The most extraordinary aspect of the monotreme genome is an amazingly complex sex chromosomes system that shares extensive homology with bird sex chromosomes and no homology with sex chromosomes of other mammals. This raises important questions about dosage compensation of the five pairs of sex chromosomes in females and meiotic silencing in males, and we are only beginning to unravel possible mechanisms and pathways that may be involved. The homology between monotreme and bird sex chromosomes makes comparison between those species worthwhile, also as they provide a well-defined example where the same sex chromosomes changed from female heterogamety (chicken) to male heterogamety (monotremes). We summarize recent research on monotreme and chicken sex chromosomes and discuss possible mechanisms that may contribute to sex chromosome silencing in monotremes.Tasman Daish and Frank Grutzne
The function of the Drosophila caspase DRONC in cell death and development
No full textdronc, the only apical caspase in Drosophila is thought to be essential and non-redundant for apoptosis. Recent analyses of several independently derived dronc mutants have demonstrated that DRONC is required for normal development. Interestingly, analysis of these mutants show that DRONC is not essential for cell death in all tissues and that in some cases, DRONC-independent effector caspase activation and apoptosis can occur. These mutants provide a valuable resource to investigate the recently reported roles of DRONC in non-apoptotic pathways. Insights gained from the dronc mutants will help in advancing our understanding of caspase function in various developmental pathways.Kathryn Mills, Tasman Daish and Sharad Kuma
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Drosophila caspase DRONC is required for specific developmental cell death pathways and stress-induced apoptosis
No full textCopyright ©2004 by Cell PressProteases of the caspase family play key roles in the execution of apoptosis. In Drosophila there are seven caspases, but their roles in cell death have not been studied in detail due to a lack of availability of specific mutants. Here, we describe the generation of a specific mutant of the Drosophila gene encoding DRONC, the only caspase recruitment domain (CARD) containing apical caspase in the fly. dronc mutants are pupal lethal and our studies show that DRONC is required for many forms of developmental cell deaths and apoptosis induced by DNA damage. Furthermore, we demonstrate that DRONC is required for the autophagic death of larval salivary glands during metamorphosis, but not for histolysis of larval midguts. Our results indicate that DRONC is involved in specific developmental cell death pathways and that in some tissues, effector caspase activation and cell death can occur independently of DRONC.Tasman J. Daish, Kathryn Mills and Sharad Kuma
Distinct promoter regions regulate spatial and temporal expression of the Drosophila caspase dronc
No full textDRONC is an apical Drosophila caspase essential for programmed cell death during fly development. During metamorphosis, dronc gene expression is regulated by the steroid hormone ecdysone, which also regulates the levels of a number of other critical cell death proteins. As DRONC protein levels are important in determining caspase activation and initiation of cell death, we have analyzed the regulation of the dronc promoter using transgenic flies expressing a LacZ reporter gene under the control of the dronc promoter. Our results indicate that dronc expression is highly dynamic during Drosophila development, and is controlled both spatially and temporally. We demonstrate that while a 2.3?kb dronc promoter region contains most of the information required for correct gene expression, a 1.1?kb promoter region is expressed in some tissues and not others. We further demonstrate that during larval-pupal metamorphosis, two ecdysone-induced transcription factors, Broad-Complex and E93, are required for correct dronc expression. Our data suggest that the dronc promoter is regulated in a highly complex manner, and provides an ideal system to explore the temporal and spatial regulation of gene expression driven by nuclear hormone receptors.T. J. Daish, D. Cakouros and S. Kuma
Deciphering the secret role of Sox4 gene locus during mouse cerebral corticogenesis
No full textAbstract no. S03-3. DOI: http://www.dx.doi.org/10.1111/jnc.12775K. H. Ling, H. C. Lee, P. J. Brautigan, S. Moore, R. Fraser, P. S. Cheah, J. M. Raison, M. Babic, Y. K. Lee, T. Daish, D. M. Mattiske, J. R. Mann, D. L. Adelson, P. Q. Thomas, C. N. Hahn, H. S. Scot
Platypus chain reaction: directional and ordered meiotic pairing of the multiple sex chromosome chain in Ornithorhynchus anatinus
No full text© CSIRO 2009Monotremes are phylogenetically and phenotypically unique animals with an unusually complex sex chromosome system that is composed of ten chromosomes in platypus and nine in echidna. These chromosomes are alternately linked (X1Y1, X2Y2, ...) at meiosis via pseudoautosomal regions and segregate to form spermatozoa containing either X or Y chromosomes. The physical and epigenetic mechanisms involved in pairing and assembly of the complex sex chromosome chain in early meiotic prophase I are completely unknown. We have analysed the pairing dynamics of specific sex chromosome pseudoautosomal regions in platypus spermatocytes during prophase of meiosis I. Our data show a highly coordinated pairing process that begins at the terminal Y5 chromosome and completes with the union of sex chromosomes X1Y1. The consistency of this ordered assembly of the chain is remarkable and raises questions about the mechanisms and factors that regulate the differential pairing of sex chromosomes and how this relates to potential meiotic silencing mechanisms and alternate segregation.Tasman Daish, Aaron Casey and Frank Grützne
An arginine-histone methyltransferase, CARMER, coordinates ecdysone-mediated apoptosis in drosophila cells
No full text© 2004 The American Society for Biochemistry and Molecular BiologyDevelopmentally programmed cell death is regulated by a balance between pro- and anti-death signaling. During Drosophila metamorphosis, the removal of larval tissues is dependent on the steroid hormone ecdys one, which controls the levels of pro- and anti-death molecules. Ecdysone binds to its heterodimeric receptor ecdysone receptor/ultraspiracle to mediate transcription of primary response genes. Here we show that CARMER, an arginine-histone methyltransferase, is critical in coordinating ecdysone-induced expression of Drosophila cell death genes. Ablation of CARMER blocks ecdysone-induced cell death in Drosophila cells, but not apoptosis induced by cell stress. We demonstrate that CARMER associates with the ecdysone receptor complex and modulates the ecdysoneinduced transcription of a number of apoptotic genes. Thus, the chromatin-modifying protein, CARMER, modulates cell death by controlling the hormone-dependent expression of the core cell death machinery.Dimitrios Cakouros, Tasman J. Daish, Kathryn Mills, and Sharad Kuma
Handwritten biographical information on Paulina T. McClung Merritt
No full textA handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.
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