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| | Slushball Earth |
 | | In trying to reconstruct the origin and radiation of metazoans over the past forty years, biologists have relied mostly on analogy and homology with the anatomy, functional ecology, and development of living animals. | | | Sure, plenty of bacteria, especially anoxic ones, would thrive; but the essence of eukaryotes is that they need oxygen for respiration. | | | Slushball Earth provides that opportunity, and, I argue, provides ideal conditions for metazoan evolution, not the catastrophically bleak conditions suggested for Snowball Earth. |
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http://www.geology.ucdavis.edu/~cowen/HistoryofLife/slushball.html
(4569 words)
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| | Palaeos Ecology : Radiations : Cambrian Explosion |
| | Unfortunately, diagenetic effects are sometimes difficult to distinguish from genuine biological structures, so we can expect the significance of this evidence to be debated for some time to come yet. | | | The observation that few fundamentally new metazoan body plans (some would say none) have arisen since. | | | Today we might regard Darwin’s views as wonderfully prescient, for numerous Precambrian fossils have now indeed been collected, and modern techniques — impossible in Darwin’s day — such as ‘molecular clock’ studies, strongly indicate metazoan evolutionary events having occurred deep within the Precambrian. |
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http://www.palaeos.com/Ecology/Radiations/CambrianExplosion.html
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| | Metazoan Life |
| | Integrated studies of the geochemical environment with dorvilleid ecology and physiology will address mechanisms of niche partitioning and explore how communities are organized under conditions of extreme sulfide stress. | | | This multidisciplinary project will introduce undergraduate, graduate and postdoctoral students and new faculty to other disciplines within biology by blending original methods and questions in physiology, ecology, molecular biology and phylogeny. | | | By mapping ecological features onto a phylogenetic framework, we will identify correlations among ecology, physiology, life history and evolutionary history that help elucidate the mechanisms of speciation under extreme stress. |
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http://levin.ucsd.edu/current_research/metazoan.html
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| | The Cambrian explosion - timing of metazoan origins |
| | Recently two different techniques have been used to investigate the timing of the metazoan radiation, and have independently placed the cladogenesis of the metazoan phyla back within the Precambrian, possibly even as far back as 1.2 billion years. | | | Both of these studies add to the growing evidence for metazoan life occuring further back in the Precambrian than previosly thought. | | | A single cladistic analysis of Recent and Cambrian arthropods (see references Fortey, Briggs & Wills. |
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http://palaeo.gly.bris.ac.uk/Palaeofiles/Cambrian/controversies/timetable/timetable.html
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| | Animals |
| | Defining phyla: evolutionary pathways to metazoan body plans. | | | Jenner, R. The scientific status of metazoan cladistics: why current research practice must change. | | | Molecular evidence that the myxozoan protists are metazoans. |
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http://tolweb.org/tree?group=Animals&contgroup=Eukaryotes
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| | Grazing by mesozooplankton and metazoan microplankton on nanophytoplankton in a mesocosm experiment in the northern ... |
| | Grazing by mesozooplankton and metazoan microplankton on nanophytoplankton in a mesocosm experiment in the northern Baltic | | | Grazing by mesozooplankton and metazoan microplankton on nanophytoplankton in a mesocosm experiment in the northern Baltic -- Uitto and Hallfors 19 (6): 655 -- Journal of Plankton Research | | | Tvarminne Zoological Station, FIN-10900 Hanko, Finland; Finnish Institute of Marine Research, PO Box 33, FIN-00931 Helsinki, Finland; Corresponding author address: Department of Ecology and Systematics, Division of Hydrobiology, PO Box 17, 00014 University of Helsinki, Finland |
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http://plankt.oupjournals.org/cgi/content/abstract/19/6/655
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| | WHY DID METAZOAN REEFS DISAPPEAR FOR FORTY MILLION YEARS IN THE EARLY PALEOZOIC?: BIOLOGICAL VS. PHYSICOCHEMICAL ... |
| | Instead, we suggest that the explanation probably lies in a nexus of physicochemical phenomena which created global conditions that inhibited metazoan reefs and promoted microbialite reefs. | | | Archaeocyaths, in particular, faced an additional problem of rapidly changing ocean chemistry. | | | The previously proposed explanations for this long post-Early Cambrian disappearance of metazoan reefs are biological in nature: no metazoan groups were available to evolve into reef-building niches, or an absence of grazers allowed calcimicrobes to flourish, or critical photosymbiotic relationships took a long time to re-evolve. |
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http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_37778.htm
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| | CSC - Intelligent Design: The Origin of Biological Information and the Higher Taxonomic Categories |
| | Yet they offered no evidence that such fields--if indeed they exist--can be altered to produce advantageous variations in body plan, though this is a necessary condition of any successful causal theory of macroevolution. | | | Those who think the fossil data provide a more reliable picture of the origin of the Metazoan tend to think these animals arose relatively quickly--that the Cambrian explosion had a “short fuse.” (Conway Morris 2003b:505-506, Valentine & Jablonski 2003). | | | Molecular evidence for deep Precambrian divergences among metazoan phyla.--Science 274:568-573. |
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http://www.discovery.org/scripts/viewDB/index.php?command=view&id=2177&progr...
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| | Biology - Open Encyclopedia |
| | One of the central, organizing concepts in biology is that all life has descended from a common origin through a process of evolution. | | | In development the theme of universal processes is also present, for example most metazoan organism the basic steps of the early embryo development share similar morphological stages and include similar genes. | | | All organisms pass on their heredity via the genetic material which is based upon the nucleic acid DNA using a universal genetic code. |
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http://open-encyclopedia.com/Biology
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| | Metazoan book search page |
| | Evolution of the Metazoan Life Cycle : A Comprehensive Theory | | | Fish Diseases and Disorders : Protozoan and Metazoan Infections | | | excuse it, as Metazoan might by the theory that the sensational element |
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http://book-to.20m.com/metazoan.html
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| | The Cambrian exposion - Controversies |
| | One thing which I hope this site makes clear is that even though the Cambrian is one of the most intensively researched periods of geological time, there are still many points of contention about the nature of the metazoan radiation event, with new discoveries and techniques adding to the picture all the time. | | | Molecular and cladistic analysis show that the divergence times of most Cambrian phyla must have occured in the Precambrian. | | | It is also clear that a morphological radiation of body forms and size does not have to be the same as a taxonomic radiation of phyla. |
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http://palaeo.gly.bris.ac.uk/Palaeofiles/Cambrian/controversies/controversies.html
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| | Molecular Evidence for Deep Precambrian Divergences Among Metazoan Phyla -- Wray et al. 274 (5287): 568 -- Science |
| | Darwin (1) recognized that the sudden appearance of animal fossils in the Cambrian posed a problem for his theory of natural selection. | | | Deep Precambrian divergence times make interpretations of some Neoproterozoic body and trace fossils less problematic. | | | It is crucial for our analysis that rates of sequence divergence are similar within the calibrating phylum and other metazoan phyla (15). |
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http://www.sciencemag.org/cgi/content/full/274/5287/568?ijkey=4Gb.zrAEYeyQM
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| | ImmInst.org -> Hydra - Immortal Metazoan life form |
| | This suggests that hydra seems to escape aging, a process known to affect all other metazoans. | | | Senescence, a deteriorative process that increases the probability of death of an organism with increasing chronological age, has been found in all metazoans where careful studies have been carried out. | | | This work has lead to an interest in investigating the presence of telomerase in hydra. |
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http://www.imminst.org/forum/index.php?act=ST&f=48&t=884&s=
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| | essential role |
| | Current hypothesis of Metazoan evolutionary relationships based on molecular and morphological studies. | | | Proposed phylogeny of protostomes based on morphological and molecular analyses. | | | Previously, using morphological methods, it was difficult to relate "minor" animal groups representing microscopic metazoans to larger, more well known groups such as arthropods, molluscs annelids. |
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http://chuma.cas.usf.edu/~garey/essential.html
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| | Evolving ``Metazoan'' Development |
| | Front page illustration: Manipulated image of a ``metazoan'' evolved in a preliminary version of the system described in this report. | | | The ``metazoan'' was called Ontosilica gastrulans since its development, during which three tissue layers are formed, resembles a gastrulation process. | | | Prelimary results suggest that the evolved genomes are hierarchically structured. |
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http://staff.science.uva.nl/~roel/metazoan
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| | The Protozoan-Metazoan Boundary |
| | Several strands of geological evidence suggest at least a temporal connection between metazoan evolution and surface oxygenation, however, there are robust arguments against what seems to be such an obvious link (see Hackstein below). | | | Zoologists themselves have been at the forefront, having proposed several models for the transition of the phenotype from uni-to multicellular animals, which will need to be rigorously tested in the years to come (see Rieger below). | | | Important References on the Protozoan and Metazoan Interphase |
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http://shum.huji.ac.il/~por/icz_xviii/protozoa.html
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| | Metazoan Parasites: Black ich, flukes, and lice in slatwater aqu |
| | I found this article interesting but it still doesn't help. | | | The past few articles have described some of the more common diseases and sicknesses that are found in aquariums. | | | Many different problems can lead to the degraded health of fish. |
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http://www.suite101.com/articles/article.cfm/1815
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| | Valentine, James W.: On the Origin of Phyla |
| | Evolutionary Changes in Body Size Occur throughout Metazoan History | | | Morphological Entities within Metazoan Bodies, Such as Cells, Can Be Positioned in Trees | | | Part One- Evidence of the Origins of Metazoan Phyla |
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http://www.press.uchicago.edu/cgi-bin/hfs.cgi/00/15826.ctl
(872 words)
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| | METAZOAN RELATIONSHIPS |
| | How do we depict evolutionary relationships among organisms? | | | All metazoans further up the cladogram have coeloms, however these coelomate metazoans come in two flavors. | | | Two types of diagrams are commonly used by biologists and paleontologists to show how organisms are related to each other. |
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http://www.es.ucsc.edu/~pkoch/lectures/lecture7.html
(899 words)
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| | American Zoologist: Metazoan relationships on the basis of 18S rRNA sequences: A few years later... |
| | (1988), SSU rRNA (18S rRNA) was also introduced to trace metazoan relationships. | | | Despite several decades of morphological and anatomical research, numerous aspects of metazoan relationships have remained uncertain (for an overview see Brusca and Brusca, 1990; Willmer, 1990; Meglitsch and Schram, 1991). | | | Most of the 18S rRNA studies focus on only one or a few aspects of metazoan phylogeny and very often include only a small part of the available 18S rRNA sequence data. |
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http://www.findarticles.com/p/articles/mi_qa3746/is_199812/ai_n8824743
(1210 words)
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| | Metazoan - definition of Metazoan in Encyclopedia |
| | Groups with this organization may be called metazoan, though that word is also used for the animals in general. | | | With a few exceptions, most notably the sponges, animals have differentiated tissues, including a nervous system and muscles, and an internal digestive chamber. | | | We know now that in so far as life and living matter can be investigated by science, animals and plants cannot be described as being alive in different degrees. |
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http://encyclopedia.laborlawtalk.com/Metazoan
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| | Alonso Cordoba, Zoology PhD Sstudent |
| | Major clades have been proposed by molecular phylogenies and are being acepted by a large portion of the scientific community, but relationships within some clades still remain unclear. | | | Traditional hypoteses for metazoan phylogeny have been based on morphological and developmental characters as well as on life history data. | | | However since the late 1980's molecular data have been used challenging some of the traditional views. |
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http://mypage.siu.edu/ajcg
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| | Literature Review: Metazoan Origins |
| | A phylogenetic framework is essential for under-standing the origin and evolution of metazoan development. | | | ISCID Forums » General » Literature Review » Metazoan Origins | | | Despite a number of recent molecular studies and a rich fossil record of sponges and cnidarians, the evolutionary relationships of the early branching metazoan groups to each other and to a putative outgroup, the choanoflagellates, remain uncertain. |
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http://www.iscid.org/boards/ubb-get_topic-f-18-t-000008.html
(315 words)
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| | Satyajit Mayor |
| | For scientists interested in studying cellular-scale phenomena, many principles from the physical sciences provide a powerful driving force in framing questions about the mechanisms of movement of molecules and organelles inside cells. | | | Development of a cell culture system from Drosophila to study the function of a variety of genes involved in endocytosis in a metazoan system | | | The broad aim of my laboratory is to provide an understanding of the molecular mechanisms of endocytosis in metazoan cells. |
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http://www.ncbs.res.in/~faculty/mayor.html
(496 words)
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| | MetaZoan - William Neal Visual Life Studio - Photography, Art, Design and Full Web Site Services |
| | A metazoan organism is separated from the external environment by barriers of jointed cells (skin, lungs, intestines, kidneys). | | | It has also a molecule with particular mechanical properties, the collagen, only found in the metazoans. | | | A living being is a metazoan (from the Greek meta, afterwards and zoon, animal), or animal, if: |
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http://www.metazoan.net
(138 words)
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| | Metazoan Parasite Infracommunities in Five Sciaenids from the Central Peruvian Coast |
| | High values of prevalence and mean abundance of infection are associated to the polyonchoinean monogeneans; the low values of J' reinforce the strong dominance of this group in the studied communities. | | | The structure of the metazoan parasite community of fish, like that of other vertebrates and invertebrates, has recently attracted some attention. | | | The first definition of a parasitic community was given by Cloutman (1975) who said that it is "the complex of individuals belonging to the different parasite species inhabiting a host". |
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http://memorias.ioc.fiocruz.br/932/3273.html
(370 words)
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| | AEPA - Metazoan Phylogeny |
| | Metazoan Phylogeny and Morphology: Data, Methods, and Alternative Hypotheses | | | Jenner, R. Evolution of animal body plans: the role of metazoan phylogeny at the interface between pattern and process. | | | Jenner, R. Metazoan phylogeny as a tool in evolutionary biology: current problems and discrepancies in application. |
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http://www.science.uva.nl/onderzoek/cepa/animalphyl.htm
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| | Eyes absent: a gene family found in several metazoan phyla [published erratum appears in Mamm Genome 1997;8(11):877]. |
| | Although Eya2 is expressed relatively late in eye development, it belongs to the growing list of factors that may be essential for eye development across metazoan phyla. | | | Like members of the Pax-6 gene family, eyes absent gene family members were probably first involved in functions not related to vision, with recruitment for visual system formation and function occurring later. | | | Eya2 shows a dynamic pattern of expression during development. |
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http://www.pdg.cnb.uam.es/UniPub/iHOP/gp/1081231.html
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| | MIT Department of Biology: David P. Bartel |
| | This work is uncovering a widespread influence of microRNAs on metazoan gene expression and numerous specific cases in which microRNAs are playing crucial roles during plant and animal development. | | | Our results pointed to a miRNA-mediated post-transcriptional restriction of Hox gene expression during vertebrate development, validated a mammalian regulatory target, and demonstrated that metazoan miRNAs can repress expression of their natural targets through mRNA cleavage. | | | briggsae, and many are conserved in more distantly related animals, including humans, suggesting important roles since early in metazoan evolution. |
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http://web.mit.edu/biology/www/facultyareas/facresearch/bartel.shtml
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| | Metazoan deep phylogenies — can the Cambrian explosion be resolved with molecular markers? |
| | Alternatively, the phylogenetic separation of major extant phyla may have already started long before the Cambrian, but fossilized material was not evolved before the Cambrian. | | | Mitochondrial DNA in metazoan is circular with different gene arrangements and different reading directions of the same gene locus and evolve ten times faster then nucleus DNA. | | | Our first results concern the two most suitable datasets of mitochondrial genome sequence comparisons and of the concatenated histone genes (H2A, H2B, H3 and H4) and their analysis (shown on GCB03/Munich). |
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http://www.iscb.org/ismb2004/posters/FritzschATizbi.uni-leipzig.de_738.html
(324 words)
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| | Identification of Metazoan and Protozoan |
| | Striated muscle in bands; much chitin in cuticle; often with tracheal | | | The key consists of characteristics of adult parasites; however, some characteristics can also be used with identification of larval forms. | | | Below is a "working" key that is to be used in identification of metazoan parasites in tissue sections. |
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http://www.afip.org/vetpath/POLA/99/GARDINER.htm
(1600 words)
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| | Molecular and genetic characterization of SLC1, a putative Saccharomyces cerevisiae homolog of the metazoan cytoplasmic ... |
| | Molecular and genetic characterization of SLC1, a putative Saccharomyces cerevisiae homolog of the metazoan cytoplasmic dynein light chain 1. | | | As part of an effort to understand the evolution and the biological roles of cytoplasmic dynein, we have identified the first non-metazoan dynein light chain 1, SLC1, in the yeast Saccharomyces cerevisiae. | | | Molecular and genetic characterization of SLC1, a putative Saccharomyces cerevisiae homolog of the metazoan cytoplasmic dynein light chain 1.The SLC1 gene lies adjacent to the YAP2 (= CAD1) transcription unit. |
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http://www.pdg.cnb.uam.es/UniPub/iHOP/gp/539657.html
(207 words)
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| | [Frontiers in Bioscience 4, d805-815, December1, 1999] |
| | However, understanding the specifics of replication in metazoan organisms can only be achieved by directly addressing these questions in animal cells. | | | This review deals with the current state of knowledge on the metazoan Origin Recognition Complex, its composition and regulation in higher eukaryotes, its role in the initiation of replication and beyond replication, and its possible connection with human pathology. | | | The discovery of the first eukaryotic initiator, the Saccharomyces cerevisiae Origin Recognition Complex (ORC) has allowed us to discern some aspects of how the onset of replication is regulated. |
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http://www.bioscience.org/1999/v4/d/quintana/list.htm
(194 words)
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