Résumé : (Statement of Responsibility) by John Burton Iverson III.
(Thesis) Thesis--University of Florida.
(Bibliography) Bibliography: leaves 353-378.
Typescript.
Vita.
Turks and Caicos Islands
UF

Droits : Copyright [name of dissertation author]. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
000185664
03349845
AAV2250

Résumé : The slides were taken on collecting trips sponsored by the William L. Bryant Foundation, where books, music and art indigenous to the regions were gathered. The are organized by geographical location.
A lizard with its raised head and tail is photographed at the base of three concrete steps. A flowering pink periwinkle bush can also be seen. Slide labeled Curved Tail Lizard April '65.
Bahamas -- North America

Droits : All rights to images are held by the respective holding institution. This image is posted publicly for non-profit educational uses, excluding printed publication. For permission to reproduce images and/or for copyright information contact Special Collections & University Archives, University of Central Florida Libraries, Orlando, FL 32816 phone (407) 823-2576, email: speccoll@mail.ucf.edu
CFM1972_01a
Sheet 13:4
http://ufdc.ufl.edu/AA00029223/00001

Éditeur(s) : [s.n.] [s.n.] ( Gainesville )
Résumé : (Bibliography) Bibliography: p. 141-143.

Droits : Copyright held by the Florida Museum of Natural History, University of Florida. All rights reserved. Text, images and other media are for nonprofit, educational, and personal use of students, scholars, and the public. Any commercial use or republication by printed or electronic media is strictly prohibited without written permission of the museum. For permission or additional information, please contact the current editor of the Bulletin at bulletin@flmnh.ufl.edu.
000440460
05069307
ACK0926
a 59009644

South America -- Peru -- Cusco -- Cusco -- Cusco
Caribbean
South America
Caribbean area
Latin America

Droits : Copyright, Erich Kesse, 2008. May be used under terms of Creative Commons license allowing Attribution + Noncommercial + ShareAlike (by-nc-sa)

South America -- Peru -- Cusco -- Cusco -- Cusco
Caribbean
South America
Caribbean area
Latin America

Droits : Copyright, Erich Kesse, 2008. May be used under terms of Creative Commons license allowing Attribution + Noncommercial + ShareAlike (by-nc-sa)

Résumé : Digitized with funding from the Digital Library of the Caribbean grant awarded by TICFIA.
South America -- Aruba -- Playa Linda
Caribbean

Droits : Copyright, Erich Kesse, 2008. May be used in accord with Creative Commons license allowing Attribution + Noncommercial + ShareAlike (by-nc-sa).

Éditeur(s) : HAL CCSD
Résumé : Enamel formation requires the involvement of secretory calcium-binding phosphoproteins. Three of them, amelogenin (AMEL), ameloblastin (AMBN) and enamelin (ENAM), have been extensively studied in mammals. More recently, a fourth protein belonging to the same family has been identified: amelotin (AMTN). AMTN has only been studied in rodents and its role during amelogenesis remains unclear.The aim of this thesis is to extend the knowledge on AMTN by studying its evolution in amniotes and its expression in the lizard Anolis carolinensis.AMTN sequences from many amniote species have been extracted from databases or obtained by PCR, and analyzed. Those analyses allowed us to reveal differences in the gene structure and to highlight residues that were conserved during mammalian or amniote evolution. These conserved amino acids are essential to the structure and/or function of the protein.The expression of AMTN and of AMEL, AMBN and ENAM has been studied by in situ hybridization on lizard jaw sections. Comparison of the expression pattern of these genes during amelogenesis in the lizard with that described in rodents points to similarities (AMEL, AMBN and ENAM) but also to important differences, especially in the spatio-temporal expression of AMTN. In order to better understand AMTN evolution in tetrapods, I studied its expression in an amphibian (Pleurodeles waltl) and a marsupial (Monodelphis domestica).Taken together, these results suggest a link between the evolution of AMTN gene structure (loss of exons and of functional domains in mammals) and its expression (early in non-mammals versus late in mammals) with the emergence of prismatic structure of enamel in early mammals.
La formation de l'émail dentaire met en jeu des phosphoprotéines sécrétées liant le calcium. Parmi celles-ci figurent amélogénine (AMEL), améloblastine (AMBN) et énaméline (ENAM), qui ont fait l'objet de nombreuses études chez les mammifères. Plus récemment, une quatrième protéine de la même famille a été découverte, l'amélotine (AMTN). Elle n'a été étudiée que chez les rongeurs et son rôle au cours de l'amélogenèse reste mal défini. L'objectif de cette thèse est d'élargir les connaissances sur AMTN en étudiant son évolution chez les amniotes et son expression au cours de l'amélogenèse chez le lézard Anolis carolinensis. Les séquences d'AMTN d'un grand nombre d'amniotes ont été extraites des bases de données ou obtenues par PCR, et analysées. Ces analyses ont mis en évidence différentes structures géniques et des acides aminés très conservés au cours de l'évolution. Cette conservation indique qu'ils sont essentiels à la structure ou à la fonction de la protéine. L'expression d'AMTN ainsi que celle d'AMEL, AMBN et ENAM ont été étudiées par hybridation in situ sur des coupes de mâchoires de lézard. La comparaison des patrons d'expression chez le lézard avec ceux décrits chez la souris a révélé des différences dans l'expression spatio-temporelle d'AMTN. De ce fait, afin de mieux comprendre l'évolution de ce gène, son expression a été étudiée chez un amphibien (Pleurodeles waltl) et un marsupial (Monodelphis domestica).Ces travaux suggère un lien entre l'évolution de la structure génique d'AMTN (perte d'exons et de domaines fonctionnels) et de son expression (précoce versus tardive) avec l'émergence de la structure prismatique de l'émail chez les mammifères.
https://tel.archives-ouvertes.fr/tel-01154518

NNT : 2015PA066066
tel-01154518
https://tel.archives-ouvertes.fr/tel-01154518
https://tel.archives-ouvertes.fr/tel-01154518/document
https://tel.archives-ouvertes.fr/tel-01154518/file/2015PA066066.pdf

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
We report on microstructural data obtained by optical microscopy and transmission electron microscopy concerning the crystallographic relationships of serpentine minerals with their host olivine in two contrasting situations. In the first case, mesh-textured lizardite (liz) is developed in a standard 60% serpentinized oceanic harzburgite from the Oman ophiolite where olivine converts to columnar lizardite. The joined columns are perpendicular to the basal plane (001)(liz), corresponding to the pseudofibres observed optically. The plane (001)(liz) is locally parallel to the narrow boundary ol-liz; thus column orientations register the interface of serpentinization. The ol-liz relationships are not strictly topotactic, but reflect preferred cracking orientations in olivine, parallel to (010)(ol). In the second case, antigorite (atg) develops in a rare sample of antigorite schist in a kimberlite from Moses Rock (Colorado Plateau), representative of a suprasubduction-zone mantle wedge. High-resolution transmission electron microscopy (HRTEM) images along [010](atg) show domains of very regular modulation with a 43 center dot 5 A wavelength (m = 17, where m is the number of silicate tetrahedra along the wave), with few defects, indicative of HP-HT antigorite, and also heavily kinked regions as fingerprints of strong tectonic shear. TEM imaging and electron diffraction patterns reveal two topotactic relationships between antigorite and olivine: [100](atg)//[010](ol) and < 100 >(atg)//< 100 >(ol); the planes in contact are (001)(atg)//(100)(ol) and (001)(atg)//(010)(ol), respectively. The [010](atg)//[001](ol) and antigorite lamellae are parallel to the forsterite b-axis. In both cases, the topography of olivine-serpentine interfaces is controlled by open fluid pathways along microcracks oriented according to the anisotropy of the olivine aggregate. In the cases studied, the serpentine aggregate exhibits a preferred orientation inherited from that of the peridotite. These results have some relevance to the seismic anisotropy of serpentinized mantle. Anisotropy of propagation of seismic waves as a result of the olivine fabric is maintained and reinforced with the development of lizardite. Conversely, the development of antigorite produces a trench-parallel fast S-wave polarization and an anisotropy that is lowered at low degrees of serpentinization and then increased with increasing serpentinization.
ISSN: 0022-3530

hal-00456061
https://hal.archives-ouvertes.fr/hal-00456061
DOI : 10.1093/petrology/egp049

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
The Lanzo peridotite massif is a fragment of oceanic lithosphere generated in an ocean-continent transition context and eclogitized during alpine collision. Despite the subduction history, the massif has preserved its sedimentary oceanic cover, suggesting that it may have preserved its oceanic structure. It is an exceptional case for studying the evolution of a fragment of the lithosphere from its oceanization to its subduction and then exhumation. We present a field and petrological study retracing the different serpentinization episodes and their impact on the massif structure. The Lanzo massif is composed of slightly serpentinized peridotites (<20% serpentinization) surrounded by an envelope of foliated serpentinites (100% serpentinization) bordered by oceanic metabasalts and metasedimentary rocks. The limit between peridotites and serpentinites defines the front of serpentinization. This limit is sharp: it is marked by the presence of massive serpentinites (80% serpentinization) and, locally, by dykes of metagabbros and mylonitic gabbros. The deformation of these gabbros is contemporaneous with the emplacement of the magma. The presence of early lizardite in the peridotites testifies that serpentinization began during the oceanization, which is confirmed by the presence of meta-ophicarbonates bordering the foliated serpentinite envelope. Two additional generations of serpentine occur in the ultramafic rocks. The first is a prograde antigorite that partially replaced the lizardite and the relict primary minerals of the peridotite during subduction, indicating that serpentinization is an active process at the ridge and in the subduction zone. Locally, this episode is followed by the deserpentinization of antigorite at peak P-T (estimated in eclogitized metagabbros at 2-2.5 GPa and 550-620 °C): it is marked by the crystallization of secondary olivine associated with chlorite and/or antigorite and of clinopyroxene, amphibole and chlorite assemblages. A second antigorite formed during exhumation partially to completely obliterating previous textures in the massive and foliated serpentinites. Serpentinites are an important component of the oceanic lithosphere generated in slow to ultraslow spreading settings, and in these settings, there is a serpentinization gradient with depth in the upper mantle. The seismic Moho limit could correspond to a serpentinization front affecting the mantle. This partially serpentinized zone constitutes a less competent level where, during subduction and exhumation, deformation and fluid circulation are localized. In this zone, the reaction kinetics are increased and the later steps of serpentinization obliterate the evidence of this progressive zone of serpentinization. In the Lanzo massif, this zone fully recrystallized into serpentinite during alpine subduction and collision. Thus, the serpentinite envelope represents the oceanic crust as defined by geophysicists, and the sharp front of serpentinization corresponds to an eclogitized seismic palaeo-Moho.
ISSN: 0263-4929

hal-00823051
https://hal.archives-ouvertes.fr/hal-00823051
DOI : 10.1111/jmg.12008

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We provide new insights into the geochemistry of serpentinites from the Alpine orogenic wedge representing a paleo-subduction zone. These serpentinites are derived from similar oceanic protoliths, but they have experienced different metamorphic conditions related to three different structural levels of the paleo-subduction zone ((1) obducted: Chenaillet ophiolite, (2) accretionary wedge: Queyras Schistes lustrés complex and (3) serpentinite channel: Monviso ophiolite). Metamorphism undergone by these three units is well defined, increasing eastward from sub-greenschist to eclogite facies conditions, and allows us to examine trace element behavior from the oceanic ridge environment to subduction. Serpentinites first record moderate trace element enrichment due to seawater interaction resulting in the replacement of olivine and pyroxene by chrysotile and lizardite below 300 °C. In the sediment-dominated accretionary wedge, serpentinites are strongly enriched in fluid-mobile-elements (B, Li, As, Sb, and Cs) and act as a trapping system following the metamorphic gradient (from 300 to 390 °C) up to total replacement of the lizardite/chrysotile assemblage by antigorite. Under higher temperature conditions (T > 390 °C), no enrichment was observed, and some fluid-mobile elements were released (B, Li, Cs, and Sr). Moreover, in the serpentinite channel (T > 460 °C), most of the fluid-mobile elements are absent due to the scarcity of metasediments which prevent geochemical exchange between metasediments and serpentinites. This is also due to the onset of antigorite breakdown and the release of fluid-mobile elements. Thus, we emphasize that the geochemistry of Alpine serpentinites is strongly dependent on (1) the grade of metamorphism and (2) the ability of metasediments to supply fluid-mobile elements. We conclude that serpentinites act as a trap-and-release system for fluid-mobile elements in a subduction context.
ISSN: 0009-2541

hal-00996839
https://hal.archives-ouvertes.fr/hal-00996839
DOI : 10.1016/j.chemgeo.2013.02.008

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: The Ras/Raf/MEK/ERK signaling pathway is involved in essential cell processes and it is abnormally activated in similar to 30 % of cancers and cognitive disorders. Two ERK isoforms have been described, ERK1 and ERK2; ERK2 being regarded by many as essential due to the embryonic lethality of ERK2 knock-out mice, whereas mice lacking ERK1 are viable and fertile. The controversial question of why we have two ERKs and whether they have differential functions or display functional redundancy has not yet been resolved. Results: To investigate this question we used a novel approach based on comparing the evolution of ERK isoforms' sequences and protein expression across vertebrates. We gathered and cloned erk1 and erk2 coding sequences and we examined protein expression of isoforms in brain extracts in all major clades of vertebrate evolution. For the first time, we measured each isoforms' relative protein level in phylogenetically distant animals using anti-phospho antibodies targeting active ERKs. We demonstrate that squamates (lizards, snakes and geckos), despite having both genes, do not express ERK2 protein whereas other tetrapods either do not express ERK1 protein or have lost the erk1 gene. To demonstrate the unexpected squamates' lack of ERK2 expression, we targeted each ERK isoform in lizard primary fibroblasts by specific siRNA-mediated knockdown. We also found that undetectable expression of ERK2 in lizard is compensated by a greater strength of lizard's erk1 promoter. Finally, phylogenetic analysis revealed that ERK1 amino acids sequences evolve faster than ERK2' s likely due to genomic factors, including a large difference in gene size, rather than from functional differences since amino acids essential for function are kept invariant. Conclusions: ERK isoforms appeared by a single gene duplication at the onset of vertebrate evolution at least 400 Mya. Our results demonstrate that tetrapods can live by expressing either one or both ERK isoforms, supporting the notion that ERK1/2 act interchangeably. Substrate recognition sites and catalytic cleft are nearly invariant in all vertebrate ERKs further suggesting functional redundancy. We suggest that future ERK research should shift towards understanding the role and regulation of total ERK quantity, especially in light of newly described erk2 gene amplification identified in tumors.
ISSN: 1471-2148

hal-01546165
https://hal.archives-ouvertes.fr/hal-01546165
DOI : 10.1186/s12862-015-0450-x

Éditeur(s) : HAL CCSD Oxford University Press (OUP): Policy B - Oxford Open Option A Oxford University Press (OUP)
Résumé : International audience
Peridotites exhumed in the footwall of axial detachment faults at slow-spreading ridges are highly serpentinized. Most mid-ocean ridge detachment settings are magmatically active and hydrous fluid circulation in and near the fault has been shown to be influenced by the presence of melt or magmatic lithologies. Our working area along the Southwest Indian Ridge (62–65°E) is nearly amagmatic and represents an end-member to study the hydrous alteration of exhumed peridotites without these magmatic influences. We use an integrated petrological approach combining microstructural, mineralogical and chemical observations to unravel the sequence of serpentinization in 272 dredged samples of variably serpentinized peridotites and to document the circulation of serpentinizing fluids in and near the exhumation faults. We find that serpentine recrystallization and veins overprint the initial serpentinite mesh texture in ∼25% of the samples. Oxygen isotope data suggest that this sequence developed at relatively high temperatures (271–336°C) and under increasing fluid–rock ratios, from near stoichiometry for mesh texture formation to >10 during recrystallization. Increasing fluid supersaturation relative to serpentine favors the replacement of mesh texture lizardite by chrysotile and polygonal or polyhedral serpentine. We attribute local recrystallization into antigorite to moderate Si-metasomatism, possibly following pyroxene serpentinization. We do not observe the more pronounced Si-metasomatism leading to talc replacing serpentine that is reported for the more magmatically active Mid-Atlantic Ridge detachment settings and is attributed to prior leaching of magmatic rocks. Scales of preferential fluid pathways in our samples evolved from pervasive and close-spaced (<500 µm) microfractures during the formation of the initial serpentine mesh texture, to centimeter-thick planar domains of enhanced fluid flux, spaced at ∼10 cm intervals and probably grouped in corridors that may be up to ∼100 m across. Serpentine minerals are enriched in some fluid-mobile elements (Cl, B, U) relative to the peridotite protolith, and several elements (Al, Fe, Si, Cu, As, Sb, REE) are redistributed at the millimeter to decimeter scale. Serpentinizing fluids were seawater-derived, probably mildly alkaline (small to no europium anomalies), reducing and H2-enriched (formation of magnetite). These fluids may have been similar to, though warmer than, those venting at the ultramafic-hosted Lost City hydrothermal fluid (30°N, Mid-Atlantic Ridge).
ISSN: 0022-3530

hal-01174047
https://hal.archives-ouvertes.fr/hal-01174047
DOI : 10.1093/petrology/egv014

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Serpentinites form by hydration of mantle peridotite and constitute the largest potential reservoir of fluid-mobile elements entering subduction zones. Isotope ratios of one such element, boron, distinguish fluid contributions from crustal versus serpentinite sources. Despite 85% of boron hosted within abyssal peridotite being lost at the onset of subduction at the lizardite-to-antigorite transition, a sufficient cargo of boron to account for the composition of island arc magma is retained (c. 7 μg g− 1, with a δ11B of + 22‰) until the down-going slab reaches the antigorite-out isograd. At this point a 11B-rich fluid, capable of providing the distinctive δ11B signature of island arc basalts, is released. Beyond the uniquely preserved antigorite-out isograd in serpentinites from Cerro del Almirez, Betic Cordillera, Spain, the prograde lithologies (antigorite–chlorite–orthopyroxene–olivine serpentinite, granofels-texture chlorite-harzburgite and spinifex-texture chlorite-harzburgite) have very different boron isotope signatures (δ11B = − 3 to + 6‰), but with no significant difference in boron concentration compared to the antigorite-serpentinite on the low P–T side of the isograd. 11B-rich fluid, which at least partly equilibrated with pelagic sediments, is implicated in the composition of these prograde lithologies, which dehydrated under open-system conditions. Serpentinite-hosted boron lost during the early stages of dehydration is readily incorporated into forearc peridotite. This, in turn, may be dragged to sub-arc depths as a result of subduction erosion and incorporated in a mélange comprising forearc serpentinite, altered oceanic crust and pelagic sediment. At the antigorite-out isograd it dehydrates, thus potentially providing an additional source of 11B-rich fluids.
ISSN: 0009-2541

hal-01172276
https://hal.archives-ouvertes.fr/hal-01172276
DOI : 10.1016/j.chemgeo.2014.03.015

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : En Indonésie orientale, entre l’île de Sumbawa et celle de Florès, se trouve le parc national de Komodo, du nom de la principale île habitée par les fameux varans, un superbe espace naturel désormais préservé par l’UNESCO et entouré de récifs coralliens. Quelques familles de pêcheurs, la plupart musulmans, peuplent ce petit archipel aujourd’hui prisé par les touristes internationaux pour ses dragons et ses lagons. En réalité, les varans géants de Komodo ne sont pas les derniers témoins de la préhistoire, mais d’énormes lézards, impressionnants, très photogéniques et parfois dangereux.Un endroit idéal pour s’adonner à une forme singulière de tourisme d’aventure, même s’il est aujourd’hui plus de masse que de niche. Entre une plage balnéaire et une balade en mini croisière, quelques dizaines de milliers de touristes annuels viennent approcher ces drôles de dragons qui effraient autant qu’ils fascinent les visiteurs. Aussi, promeneurs, baigneurs et excursionnistes se croisent — le temps d’un frisson bien encadré, il est vrai dans un décor de rêve — dans ce parc national, tous animés par les mêmes volontés et curiosité de « voir pour de vrai » cette créature étrange qui stimule notre imaginaire rempli de dinosaures.
In eastern Indonesia, between the island of Sumbawa and Flores that, is the Komodo National Park, named after the main island where the famous lizards are found, a beautiful natural area now protected by UNESCO and surrounded by reefs coral. Some families of fishermen, most Muslims inhabit this small archipelago prized today by international tourists for its dragons and lagoons. In reality, the giant Komodo dragons are the last witnesses of prehistory but huge lizards, impressive, photogenic and sometimes dangerous.An ideal place to indulge in a singular form of adventure tourism, although it is now more mass than niche. Between a seaside beach and a leisurely mini cruise, tens of thousands of annual tourists come to approach these funny dragons that scare as they fascinate visitors. Also, walkers, swimmers and hikers cross - time for a well supported thrill, it is true in a dream setting - in this national park, all driven by the same desire and curiosity to "see for real" this creature strange that stimulates our imagination filled with dinosaurs.
Indonésie
Komodo
Bali

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.7577
http://journals.openedition.org/etudescaribeennes/7577

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Serpentinites are one of the major components of the oceanic lithosphere and are stable in the slab and the mantle wedge up to 100-150 km depth in subduction zones. During oceanic mantle hydration and alteration, they trap trace and fluid mobile (FME: B, Li, As, Sb, Rb, Ba, Cs, Sr, U and Pb) elements that participate to elemental transfer occurring between the dehydrating slab and the mantle wedge in subduction context. The Lanzo massif is an eclogitized oceanic lithosphere that preserved its oceanic structure and recorded different steps of serpentinization/de-serpentinization from oceanic lizardite to prograde antigorite in subduction context, up to its dehydration and secondary olivine crystallization, and finally retrograde antigorite during massif exhumation. It constitutes a suitable place to study trace element behavior during serpentinization/de-serpentinization processes and associated chemical transfers between the different envelopes of the oceanic lithosphere and the mantle wedge. Geochemical analyses of serpentine and associated minerals show that the serpentinization/de-serpentinization of the Lanzo massif took place in a relatively closed system without significant trace element transfer between the different parts of the oceanic lithosphere. In the deeper part of the lithosphere, from the slightly serpentinized mantle peridotites (SSP, < 20% serpentinization) to the paleo-Moho, composed of massive serpentinites (MS, 80% serpentinization), the trace elements mobility is reduced. The chemical composition of lizardite and antigorite is homogenized with the local degree of serpentinization: in SSP, serpentine veins composition is inherited from the host mineral while, in MS, their composition is homogenous between destabilized phases at the scale of the outcrop (~ 5 m). In the shallowest part of the oceanic lithosphere, from the paleo-Moho to the oceanic paleo-seafloor, the serpentinites are foliated (FS, > 90% serpentinization). In that zone, the alpine deformation enhances the mobility of trace elements and permits their redistribution and the homogenization of antigorite composition at massif scale. Locally, in the SSP and MS, the crystallization of metamorphic veins of ~ 1-2 m corresponds to channelized fluid flows that allowed fluid transfers - and thereby trace elements - to longer distance. The successive crystallizations of antigorite and then olivine are accompanied by a diminution of some FME (B, Li, As, Sb, Ba, Rb) and Eu contents attesting that these elements are removed from slab to mantle wedge during subduction.
ISSN: 0009-2541

hal-00937661
https://hal.archives-ouvertes.fr/hal-00937661
DOI : 10.1016/j.chemgeo.2013.08.025

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background : In a recent study, we have demonstrated that amelotin (AMTN) gene structure and its expression during amelogenesis have changed during tetrapod evolution. Indeed, this gene is expressed throughout enamel matrix deposition and maturation in non-mammalian tetrapods, while in mammals its expression is restricted to the transition and maturation stages of amelogenesis. Previous studies of amelogenin (AMEL) gene expression in a lizard and a salamander have shown similar expression pattern to that in mammals, but to our knowledge there are no data regarding ameloblastin (AMBN) and enamelin (ENAM) expression in non-mammalian tetrapods. The present study aims to look at, and compare, the structure and expression of four enamel matrix protein genes, AMEL, AMBN, ENAM and AMTN during amelogenesis in the lizard Anolis carolinensis.Results : We provide the full-length cDNA sequence of A. carolinensis AMEL and AMBN, and show for the first time the expression of ENAM and AMBN in a non-mammalian species. During amelogenesis in A. carolinensis, AMEL, AMBN and ENAM expression in ameloblasts is similar to that described in mammals. It is noteworthy that AMEL and AMBN expression is also found in odontoblasts. Conclusions : Our findings indicate that AMTN is the only enamel matrix protein gene that is differentially expressed in ameloblasts between mammals and sauropsids. Changes in AMTN structure and expression could be the key to explain the structural differences between mammalian and reptilian enamel, i.e. prismatic versus non-prismatic.
ISSN: 2041-9139

Droits : http://creativecommons.org/licenses/by/
hal-01206550
http://hal.upmc.fr/hal-01206550
http://hal.upmc.fr/hal-01206550/document
http://hal.upmc.fr/hal-01206550/file/Gasse_2015_Comparative.pdf
DOI : 10.1186/s13227-015-0024-4

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Serpentinization of olivine-rich troctolite from core 227, Integrated Ocean Drilling Program (IODP) Hole U1309D ranges from 10 to 90. Two episodes of serpentinization are recognized. The first, dominant in weakly serpentinized samples, is an approximately isochemical (except for water) replacement of olivine (Fo(8485)) by a mixture of serpentine (antigorite, Mg-number 92) and brucite (amakinite-rich; Mg-number 65). The compositions of the minerals in type 1 veins are a reflection of FeMg exchange between olivine and the brucite serpentine formed during early serpentinization. The early serpentinite veins (type 1) are thin ( 005 mm), irregular, and exploit pre-existing cracks in olivine. The presence of antigorite suggests that early serpentinization occurred at T 300C. Type 1 veins reflect rock-dominated serpentinization, became isolated early in their history, and persist as relicts in all but the most altered samples. The main episode of serpentinization is manifested by through-going lizardite (average Mg-number 96)magnetite veins (type 2). Type 2 veins define an anastomosing foliation, may be several millimeters in width and appear to exploit pre-existing, favorably oriented type 1 veins. Type 2 veins reflect open-system serpentinization. Magnetite in these veins formed by oxidation of the Fe in brucite and serpentine, whereas addition of silica to the system converted the Mg-component of the brucite to serpentine. Magnetite forms one or more distinct bands in the interior of the vein and is never in direct contact with relict olivine. A bruciteserpentine mixture, similar to that found in type 1 veins, but with lizardite instead of antigorite, is commonly present at the margins of type 2 veins (i.e. where they are in reaction contact with relict olivine). We interpret type 2 veins as a steady-state system where brucite continually forms at the olivinevein contact and then reacts out in the interior of the vein. This continual formation and destruction of brucite imposes an exceptionally low a(SiO2) on the system. Magnetite and olivine are never in contact in type 2 veins (or anywhere else) because the olivine-out reaction yields ferroan brucite and not magnetite. The desilication of serpentine in the type 2 veins is a reflection of the inherent instability of Fe-rich serpentine with respect to magnetite at low silica activity. Thus, the composition of serpentine in equilibrium with magnetite in serpentinites is a function of serpentinemagnetite and not serpentineolivine equilbria.
ISSN: 0022-3530

hal-00420931
https://hal.archives-ouvertes.fr/hal-00420931
DOI : 10.1093/petrology/egp004

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Well studied in mammals, amelogenesis is less known at the molecular level in reptiles and amphibians. In the course of extensive studies of enamel matrix protein (EMP) evolution in tetrapods, we look for correlation between changes in protein sequences and temporospatial protein gene expression during amelogenesis, using an evo-devo approach. Our target is the major EMP, amelogenin (AMEL) that plays a crucial role in enamel structure. We focused here our attention to an amphibian, the salamander Pleurodeles waltl. RNAs were extracted from the lower jaws of a juvenile P. waltl and the complete AMEL sequence was obtained using PCR and RACE PCR. The alignment of P. waltl AMEL with other tetrapodan (frogs, reptiles and mammals) sequences revealed residue conservation in the N- and C-terminal regions, and a highly variable central region. Using sense and anti-sense probes synthetized from the P. waltl AMEL sequence, we performed in situ hybridization on sections during amelogenesis in larvae, juveniles, and adults. We demonstrated that (i) AMEL expression was always found to be restricted to ameloblasts, (ii) the expression pattern was conserved through ontogeny, even in larvae where enameloid is present in addition to enamel, and (iii) the processes are similar to those described in lizards and mammals. These findings indicate that high variations in the central region of AMEL have not modified its temporospatial expression during amelogenesis for 360 million years of tetrapod evolution. J. Exp. Zool. (Mol. Dev. Evol.) 320B:200209, 2013.
ISSN: 1552-5007

hal-01545483
https://hal.archives-ouvertes.fr/hal-01545483
DOI : 10.1002/jez.b.22494

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We sought transversotrematid trematodes from French Polynesian fishes by examining 304 individual scaled fishes of 53 species from seven families known to harbour the family elsewhere. A single species was found at two locations in the Tuamotus Archipelago on two species of Chaetodontidae (Chaetodon auriga and Chaetodon ephippium) and one species of Lutjanidae (Lutjanus gibbus). The species closely resembles Transversotrema borboleta Hunter & Cribb, 2012 from chaetodontids and lutjanids of the northern Great Barrier Reef (GBR) but differs from it consistently in 8 base positions of ITS2 rDNA. This level of variation exceeds that between some clearly morphologically distinct pairs of species of Transversotrema and the form from French Polynesia is thus interpreted as a distinct, though cryptic, species and named Transversotrema polynesiae n. sp. The new species forms part of a complex of species, here characterised as the T. borboleta complex, associated with chaetodontids and lutjanids in the tropical Indo-West Pacific. Most of the putative species within this complex are yet to be described. Comparison of identical numbers of matched samples of fishes from French Polynesia, Heron Island (southern GBR) and Lizard Island (northern GBR) revealed 1, 4 and 10 species of Transversotrema respectively suggesting that the French Polynesian fauna is depauperate for this family. In addition to those species apparently missing from suitable hosts in French Polynesia, several species from further west infect fishes (especially Nemipteridae) that are themselves absent from French Polynesia. This dramatic east–west decline in richness contrasts strongly with what is known for monogeneans, which appear to maintain their richness over the same scale, and is more precipitate than is known for other groups of trematodes. The decline might be explained in part by the absence of the as yet unknown first intermediate hosts in French Polynesia. However, we predict that it is explained by other life cycle traits. We hypothesise that the characters of large short-lived cercariae, short-lived miracidia, the absence in the life-cycle of second intermediate hosts that are capable of transporting the species, and definitive and first intermediate hosts that have limited vagility combine to give marine Transversotrematidae limited dispersal capacity and a propensity for localised speciation.
ISSN: 1383-5769

hal-01333467
https://hal-univ-perp.archives-ouvertes.fr/hal-01333467
DOI : 10.1016/j.parint.2013.11.009

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: Amelotin (AMTN) is an ameloblast-secreted protein that belongs to the secretory calcium-binding phosphoprotein (SCPP) family, which originated in early vertebrates. In rodents, AMTN is expressed during the maturation stage of amelogenesis only. This expression pattern strongly differs from the spatiotemporal expression of other ameloblast-secreted SCPPs, such as the enamel matrix proteins (EMPs). Furthermore, AMTN was characterized in rodents only. In this study, we applied various approaches, including in silico screening of databases, PCRs and transcriptome sequencing to characterize AMTN sequences in sauropsids and amphibians, and compared them to available mammalian and coelacanth sequences. Results: We showed that (i) AMTN is tooth (enamel) specific and underwent pseudogenization in toothless turtles and birds, and (ii) the AMTN structure changed during tetrapod evolution. To infer AMTN function, we studied spatiotemporal expression of AMTN during amelogenesis in a salamander and a lizard, and compared the results with available expression data from mouse. We found that AMTN is expressed throughout amelogenesis in non-mammalian tetrapods, in contrast to its expression limited to enamel maturation in rodents. Conclusions: Taken together our findings suggest that AMTN was primarily an EMP. Its functions were conserved in amphibians and sauropsids while a change occurred early in the mammalian lineage, modifying its expression pattern during amelogenesis and its gene structure. These changes likely led to a partial loss of AMTN function and could have a link with the emergence of prismatic enamel in mammals.
ISSN: 1471-2148

Droits : http://creativecommons.org/licenses/by/
hal-01212821
http://hal.upmc.fr/hal-01212821
http://hal.upmc.fr/hal-01212821/document
http://hal.upmc.fr/hal-01212821/file/s12862-015-0329-x.pdf
DOI : 10.1186/s12862-015-0329-x