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Bruce P Brandhorst

Publications and source records attributed to Bruce P Brandhorst.

7 recordsLinked to original sources
PubMed2006

The echinoderm adhesome.

Although the development of sea urchin embryos has been studied extensively and clearly involves both cell adhesion and cell migration, rather little is known about the adhesion receptors and extracellular matrix molecules involved. The completion of the genome of Strongylocentrotus purpuratus allows a comprehensive survey of the complement of cell-cell and cell-matrix adhesion molecules in this organism. Furthermore, the phylogenetic position of echinoderms offers the opportunity to compare the complement of adhesion proteins between protostome and deuterostome invertebrates and between invertebrate and vertebrate deuterostomes. Many aspects of development and cell interactions differ among these different taxa and it is likely that analysis of the spectrum of adhesion receptors and extracellular matrix proteins can open up new insights into which molecules have evolved to suit particular developmental processes. In this paper, we report the results of an initial analysis along these lines. The echinoderm adhesome (complement of adhesion-related genes/proteins) is similar overall to that of other invertebrates although there are significant deuterostome-specific innovations and some interesting features previously thought to be chordate or vertebrate specific.

Animals↗
PubMed2002

HSP90 function is required for morphogenesis in ascidian and echinoid embryos.

Treatment of embryos of the ascidians Boltenia villosa and Cnemidocarpa finmarkiensis and the sea urchin Strongylocentrotus purpuratus with the anti-HSP90 drugs geldanamycin and radicicol caused morphogenetic arrest. All embryonic stages during which obvious morphogenesis was observed were sensitive to treatment, including formation of the sea urchin blastular epithelium. Arrested embryos were viable for many hours to days post-treatment, indicating a low general toxicity of these drugs. Morphogenetic movements including gastrulation and migration (but not ingression) of sea urchin primary and secondary mesenchyme cells were arrested 8-10 h after treatment began. Cell division and developmentally regulated expression of some genes continued after morphogenesis was arrested. Anti-HSP90 drugs cause selective inactivation or degradation of proteins with which the protein chaperone HSP90 interacts. Therefore, morphogenetic arrest subsequent to the disruption of HSP90 function may result from the reduction in concentration, or activity, of client proteins required for morphogenetic movements of cells. The use of these drugs may provide a means to identify novel activities or proteins involved in morphogenesis.

Alkaline Phosphatase↗
PubMed2002

Molecular patterning along the sea urchin animal-vegetal axis.

The molecular regulatory mechanisms underlying primary axis formation during sea urchin development have recently been identified. Two opposing maternally inherited systems, one animalizing and one vegetalizing, set up the animal-vegetal (A-V) axis. The vegetal system relies in part on the Wnt-beta-catenin-Tcf/Lef signaling pathway and the animal system is based on a cohort of animalizing transcription factors that includes members of the Ets and Sox classes. The two systems autonomously define three zones of cell-type specification along the A-V axis. The vegetalmost zone gives rise to the skeletogenic mesenchyme lineage; the animalmost zone gives rise to ectoderm; and the zone in which the two systems overlap generates endoderm, secondary mesenchyme, and ectoderm. Patterning along the A-V also depends on cellular interactions involving Wnt, Notch, and BMP signaling. We discuss how these systems impact the formation of the second axis, the oral-aboral axis; how they connect to later developmental events; and how they lead to cell-type-specific gene expression via cis-regulatory networks associated with transcriptional control regions. We also discuss how these systems may confer on the embryo its spectacular regulatory capacity to replace missing parts.

Animals↗
PubMedDate not supplied

Assignment of sockeye salmon (Oncorhynchus nerka) to spawning sites using DNA markers.

Randomly amplified polymorphic DNA (RAPD) markers were used to assign individual adult sockeye salmon to their spawning sites using a genotype assignment test. Six primers were selected for use by screening bulked DNA samples for markers missing in fish from one or more of 5 sites in British Columbia or Alaska. Of 73 markers scored, 54 showed variation between or within sites among the sampled fish. Thirty-seven of the variable markers were not detected in any fish from one or more sites; 18 variable markers were detected in all fish from one or more other sites. Thus 25% of markers scored were found in all fish of some sites and in no fish of some other sites. An assignment test placed all 70 fish tested into their correct populations. Principal coordinate analysis of genetic variation produced clusters of fish corresponding to each sampling site. No sex-specific RAPD markers were detected among more than 1300 screened.

Alaska↗
PubMedDate not supplied

On nitric oxide signaling, metamorphosis, and the evolution of biphasic life cycles.

Complex life cycles are ancient and widely distributed, particularly so in the marine environment. Generally, the marine biphasic life cycle consists of pre-reproductive stages that exist in the plankton for various periods of time before settling and transforming into a benthic reproductive stage. Pre-reproductive stages are frequently phenotypically distinct from the reproductive stage, and the life cycle transition (metamorphosis) linking the larval and juvenile stages varies in extent of change but is usually rapid. Selection of suitable adult sites apparently involves the capacity to retain the larval state after metamorphic competence is reached. Thus two perennial and related questions arise: How are environmentally dependent rapid transitions between two differentiated functional life history stages regulated (a physiological issue) and how does biphasy arise (a developmental issue)? Two species of solitary ascidian, a sea urchin and a gastropod, share a nitric oxide (NO)-dependent signaling pathway as a repressive regulator of metamorphosis. NO also regulates life history transitions among several simple eukaryotes. We review the unique properties of inhibitory NO signaling and propose that (a) NO is an ancient and widely used regulator of biphasic life histories, (b) the evolution of biphasy in the metazoa involved repression of juvenile development, (c) functional reasons why NO-based signaling is well suited as an inhibitory regulator of metamorphosis after competence is reached, and (d) signaling pathways that regulate metamorphosis of extant marine animals may have participated in the evolution of larvae.

Animals↗