1,346 results match your criteria: "Research School of Biological Sciences[Affiliation]"

Mammalian sex--Origin and evolution of the Y chromosome and SRY.

Semin Cell Dev Biol

June 2007

Comparative Genomics Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, ACT 2601, Canberra, Australia.

Sex determination in vertebrates is accomplished through a highly conserved genetic pathway. But surprisingly, the downstream events may be activated by a variety of triggers, including sex determining genes and environmental cues. Amongst species with genetic sex determination, the sex determining gene is anything but conserved, and the chromosomes that bear this master switch subscribe to special rules of evolution and function.

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Research note: Energy partitioning in photosystem II complexes subjected to photoinhibitory treatment.

Funct Plant Biol

April 2007

ARC Centre for Excellence in Plant Energy Biology, Research School of Biological Sciences, Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.

Chlorophyll a fluorescence measured in vivo is frequently used to study the role of different processes influencing the distribution of excitation energy in PSII complexes. Such studies are important for understanding the regulation of photosynthetic electron transport. However, at the present time, there is no unified methodology to analyse the energy partitioning in PSII.

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Does gene dosage really matter?

J Biol

February 2008

Research School of Biological Sciences, Australian National University, Canberra, ACT 2601, Australia.

Mechanisms to compensate for dosage differences of genes on sex chromosomes are widespread in animals and have been thought to be critical for viability. However, in birds, compensation is inefficient, implying that for many genes dosage compensation is not critical, and for some genes, dosage differences have even been selected for.

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Rhizobium-initiated rice growth inhibition caused by nitric oxide accumulation.

Mol Plant Microbe Interact

March 2007

ARC Centre of Excellence for Integrative Legume Research, Research School of Biological Sciences, Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.

Isolates of Rhizobium leguminosarum bv. trifolii (the clover root-nodule endosymbiont) from the Nile River delta have been found to infect rice roots and colonize the intercellular spaces of the rice roots. Some of these isolates inhibit rice seedling growth but one in particular, R4, has been found in rice roots which develop and grow normally.

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Characterization of a metabotropic glutamate receptor in the honeybee (Apis mellifera): implications for memory formation.

Invert Neurosci

June 2007

Visual Sciences and ARC Centre for the Molecular Genetics of Development, Research School of Biological Sciences, The Australian National University, Canberra, ACT 0200, Australia.

G-protein-coupled metabotropic glutamate receptors (GPC mGluRs) are important constituents of glutamatergic synapses where they contribute to synaptic plasticity and development. Here we characterised a member of this family in the honeybee. We show that the honeybee genome encodes a genuine mGluR (AmGluRA) that is expressed at low to medium levels in both pupal and adult brains.

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Previous work has suggested that dragonfly ocelli are specifically adapted to resolve horizontally extended features of the world, such as the horizon. We investigate the optical and anatomical properties of the median ocellus of Hemicordulia tau and Aeshna mixta to determine the extent to which the findings support this conclusion. Dragonfly median ocelli are shown to possess a number of remarkable properties: astigmatism arising from the elliptical shape of the lens is cancelled by the bilobed shape of the inner lens surface, interference microscopy reveals complex gradients of refractive index within the lens, the morphology of the retina results in zones of high acuity, and the eye has an exceedingly high sensitivity for a diurnal terrestrial invertebrate.

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Form vision in the insect dorsal ocelli: an anatomical and optical analysis of the Locust Ocelli.

Vision Res

May 2007

Centre for Visual Sciences, Research School of Biological Sciences, Australian National University, Canberra, Australia.

The dorsal ocelli are commonly considered to be incapable of form vision, primarily due to underfocused dioptrics. We investigate the extent to which this is true of the ocelli of the locust Locusta migratoria. Locust ocelli contain thick lenses with a pronounced concavity on the inner surface, and a deep clear zone separating retina and lens.

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GeneBins: a database for classifying gene expression data, with application to plant genome arrays.

BMC Bioinformatics

March 2007

ARC Centre of Excellence for Integrative Legume Research and Bioinformatics Laboratory, Genomic Interactions Group, Research School of Biological Sciences, Australian National University, Canberra, Australia.

Background: To interpret microarray experiments, several ontological analysis tools have been developed. However, current tools are limited to specific organisms.

Results: We developed a bioinformatics system to assign the probe set sequences of any organism to a hierarchical functional classification modelled on KEGG ontology.

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Analyzing microarray data using CLANS.

Bioinformatics

May 2007

ARC Centre of Excellence for Interactive Legume Research and Bioinformatics Laboratory, Genomic Interactions Group, Research School of Biological Sciences, Australian National University, Canberra, ACT, Australia

Unlabelled: Analysis of microarray experiments is complicated by the huge amount of data involved. Searching for groups of co-expressed genes is akin to searching for protein families in a database as, in both cases, small subsets of genes with similar features are to be found within vast quantities of data. CLANS was originally developed to find protein families in large sets of amino acid sequences where the amount of data involved made phylogenetic approaches overly cumbersome.

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A proteome study of the proliferation of cultured Medicago truncatula protoplasts.

Proteomics

March 2007

Australian Research Council Centre of Excellence for Integrative Legume Research, Genomic Interactions Group, Research School of Biological Sciences, Australian National University, Canberra, Australia.

A proteome study of the first five days of Medicago truncatula protoplast cultures was done to investigate molecular changes taking place during protoplast proliferation. A total of 1556 protein spots were analysed, of which 886 protein spots showed significant (p<0.005) changes in abundance at some time during the first five days of protoplast culture.

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Marsupial, as well as eutherian, mammals are subject to X chromosome inactivation in the somatic cells of females, although the phenotype and the molecular mechanism differ in important respects. Monotreme mammals appear to subscribe at least to a form of dosage compensation of X-borne genes. An important question is whether inactivation in these non-eutherian mammals involves co-ordination by a control locus homologous to the XIST gene and neighbouring genes, which play a key regulatory role in human and mouse X inactivation.

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Hypothesis. Air embolisms exsolving in the transpiration water - the effect of constrictions in the xylem pipes.

Funct Plant Biol

March 2007

Environmental Biology Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 0200, Australia.

When water flows through a constriction, air can come out of solution (i.e. it can exsolve).

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Flightless I deficiency enhances wound repair by increasing cell migration and proliferation.

J Pathol

April 2007

Molecular Genetics and Evolution Group and Centre for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, Canberra, ACT, Australia.

Wound healing disorders are a therapeutic problem of increasing clinical importance involving substantial morbidity, mortality, and rising health costs. Our studies investigating flightless I (FliI), a highly conserved actin-remodelling protein, now reveal that FliI is an important regulator of wound repair whose manipulation may lead to enhanced wound outcomes. We demonstrate that FliI-deficient + /- mice are characterized by improved wound healing with increased epithelial migration and enhanced wound contraction.

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Mapping platypus SOX genes; autosomal location of SOX9 excludes it from sex determining role.

Cytogenet Genome Res

March 2007

Comparative Genomics Group, Research School of Biological Sciences, The Australian National University, Canberra, Australia.

In the absence of an SRY orthologue the platypus sex determining gene is unknown, so genes in the human testis determining pathway are of particular interest as candidates. SOX9 is an attractive choice because SOX9 deletions cause male-to-female sex reversal in humans and mice, and SOX9 duplications cause female-to-male sex reversal. We have localized platypus SOX9, as well as the related SOX10, to platypus chromosomes 15 and 10, respectively, the first assignments to these platypus chromosomes, and the first comparative mapping markers from human chromosomes 17 and 22.

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Class I genes have split from the MHC in the tammar wallaby.

Cytogenet Genome Res

March 2007

ARC Centre for Kangaroo Genomics, Research School of Biological Sciences, The Australian National University, Canberra, Australia.

Genes within the Major Histocompatibility Complex (MHC) are critical to the immune response and immunoregulation. Comparative studies have revealed that the MHC has undergone many changes throughout evolution yet in tetrapods the three different classes of MHC genes have maintained linkage, suggesting that there may be some functional advantage obtained by maintaining this clustering of MHC genes. Here we present data showing that class II and III genes, the antigen processing gene TAP2, and MHC framework genes are found together in the tammar wallaby on chromosome 2.

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Analysis of Mgm101p isolated from mitochondria shows that the mature protein of 27.6 kDa lacks 22 amino acids from the N-terminus. This mitochondrial targeting sequence has been incorporated in the design of oligonucleotides used to determine a functional core of Mgm101p.

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Cyanobacterial photosynthesis occurs in radically diverse habitats and utilizes various forms of a CO(2)-concentrating mechanism (CCM) featuring multiple inorganic carbon (C(i)) transporters. Cyanobacteria from dynamic environments can transform CCM activity depending on C(i) availability, and yet the molecular basis for this regulation is unclear, especially in coastal strains. LysR family transcription factors resembling the Calvin cycle regulator CbbR from proteobacteria have been implicated in the expression of C(i) transporter genes in freshwater cyanobacteria.

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Creating functional artificial proteins.

Curr Protein Pept Sci

February 2007

Research School of Biological Sciences, The Australian National University, Canberra, ACT 0200, Australia.

Much is now known about how protein folding occurs, through the sequence analysis of proteins of known folding geometry and the sequence/structural analysis of proteins and their mutants. This has allowed not only the modification of natural proteins but also the construction of de novo polypeptides with predictable folding patterns. Structure/function analysis of natural proteins is used to construct derived versions that retain a degree of biological activity.

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Honeybee navigation: distance estimation in the third dimension.

J Exp Biol

March 2007

Centre for Excellence in Vision Science, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 2601, Australia.

Honeybees determine distance flown by gauging the extent to which the image of the environment moves in the eye as they fly towards their goal. Here we investigate how this visual odometer operates when a bee flies along paths that include a vertical component. By training bees to fly to a feeder along tunnels of various three-dimensional configurations, we find that the odometric signal depends only upon the total distance travelled along the path and is independent of its three-dimensional configuration.

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The F1-ATPase inhibitor Inh1 (IF1) affects suppression of mtDNA loss-lethality in Kluyveromyces lactis.

FEMS Yeast Res

August 2007

Molecular Genetics and Evolution Group, Research School of Biological Sciences, The Australian National University, Canberra, Australia.

Loss of mtDNA by the petite-negative yeast Kluyveromyces lactis is lethal (rho(o)-lethality). However, mutations in the alpha, beta and gamma subunits of F(1)-ATPase can suppress lethality by increasing intramitochondrial hydrolysis of ATP. Increased hydrolysis of ATP can also occur on inactivation of Inh1, the natural inhibitor of F(1)-ATPase.

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The mapping of visual space by dragonfly lateral ocelli.

J Comp Physiol A Neuroethol Sens Neural Behav Physiol

May 2007

Centre for Visual Sciences, Research School of Biological Sciences, Australian National University, Canberra, Australia.

We study the extent to which the lateral ocelli of dragonflies are able to resolve and map spatial information, following the recent finding that the median ocellus is adapted for spatial resolution around the horizon. Physiological optics are investigated by the hanging-drop technique and related to morphology as determined by sectioning and three-dimensional reconstruction. L-neuron morphology and physiology are investigated by intracellular electrophysiology, white noise analysis and iontophoretic dye injection.

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Comparing injection, feeding and topical application methods for treatment of honeybees with octopamine.

J Insect Physiol

February 2007

Visual Sciences and ARC Centre for Molecular Genetics of Development, Research School of Biological Sciences, The Australian National University, Canberra, ACT 2601, Australia.

Entomologists have used a range of techniques to treat insects with neuroactive compounds, but it is not always clear whether different treatment methods are equally effective in delivering a compound to a target organ. Here, we used five different techniques to treat honeybees with 3H-octopamine (3H-OA), and analysed the distribution of the 3H radiolabelled compound within different tissues and how it changed over time. All treatment methods, including injection of the median ocellus, resulted in 3H-OA detection in all parts of the honeybee.

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Reassignment of chicken W chromosome sequences to the Z chromosome by fluorescence in situ hybridization (FISH).

Cytogenet Genome Res

April 2007

Comparative Genomics Group, Research School of Biological Sciences, The Australian National University, Canberra, Australia.

There is much interest in the gene content of the small heterochromatic W chromosome of the chicken, on the supposition that it may contain sex-determining genes. A considerable region in the chicken genome has been assigned to the W chromosome on the basis of its repetitive sequences. Using fluorescent in situ hybridization (FISH) we localized five Bacterial Artificial Chromosomes (BACs) onto female chicken metaphase spreads.

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Novel cuticular proteins revealed by the honey bee genome.

Insect Biochem Mol Biol

February 2007

ARC Centre for the Molecular Genetics of Development and Visual Sciences, Research School of Biological Sciences, The Australian National University, Canberra, ACT 0200, Australia.

With the completion of the honey bee genome project, a transition is now occurring from the acquisition of gene sequence to understanding the role and context of gene products within the genome. Here we annotated and characterised a cluster of three genes in a GC-rich 11 kb genomic region on the linkage group 4 encoding highly hydrophobic polypeptides (named apidermins; APD 1-3) containing both sequence motifs characteristic of cuticular proteins and distinctly novel features. Five amino acids, Ala, Gly, Leu, Pro and Val, account for 74-86% of their respective sequences with Ala being the most abundant residue (at least 30% of each peptide).

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