Your browser doesn't support javascript.
loading
Montrer: 20 | 50 | 100
Résultats 1 - 6 de 6
Filtrer
Plus de filtres











Base de données
Gamme d'année
1.
PLoS One ; 13(5): e0191304, 2018.
Article de Anglais | MEDLINE | ID: mdl-29718917

RÉSUMÉ

Obligate river dolphins occur only in the rivers of Asia and South America, where they are increasingly subject to damaging pressures such as habitat degradation, food competition and entanglement in fishing gear as human populations expand. The Amazon basin hosts two, very different, dolphins-the boto or Amazon river dolphin (Inia geoffrensis) and the smaller tucuxi (Sotalia fluviatilis). Both species have wide geographical ranges and were once considered to be relatively abundant. Their IUCN Red List conservation status of Data Deficient (DD), due to limited information on threats, ecology, population numbers and trends, did not initially cause alarm. However, the development of dolphin hunting to provide fish bait at around the beginning of this millennium broadly coincided with the onset of a widespread perception that numbers of both species were in decline. Consequently, the need for population trend data to inform conservation advice and measures became urgent. This paper presents a 22-year time series of standardised surveys for both dolphins within the Mamirauá Reserve, Amazonas State, Brazil. Analysis of these data show that both species are in steep decline, with their populations halving every 10 years (botos) and 9 years (tucuxis) at current rates. These results are consistent with published, independent information on survival rates of botos in this area, which demonstrated a substantial drop in annual survival, commencing at around the year 2000. Mamirauá is a protected area, and is subject to fewer environmental pressures than elsewhere in the region, so there is no reason to suspect that the decline in dolphins within the Reserve is more pronounced than outside it. If South America's freshwater cetaceans are to avoid following their Asian counterparts on the path to a perilous conservation status, effective conservation measures are required immediately. Enforcement of existing fishery laws would greatly assist in achieving this.


Sujet(s)
Cetacea , Animaux , Brésil , Modèles statistiques , Dynamique des populations
2.
Anat Rec (Hoboken) ; 300(8): 1519-1523, 2017 08.
Article de Anglais | MEDLINE | ID: mdl-28257606

RÉSUMÉ

The spermatozoa from seven adult Amazon river dolphins (Inia geoffrensis, CETACEA: INIIDAE) were analyzed by light and electron microscopy. The spermatozoa showed an elongated ellipsoid shaped head and a long tail with a well distinguishable midpiece. The head spermatozoa have a smooth surface like other odontocetes examined, with the exception of the Delphinidae family. The mean dimensions of the spermatozoa were within the range already reported for other cetaceans. The spermatozoa midpiece, as in other cetaceans, showed a random pattern of mitochondria, different from that described for other mammals. Further studies of sperm morphology of a wider spectrum of cetacean families could help to better understand the reproductive biology of these animals and the intergeneric and intrageneric relationships among them, as well as, among other mammals. Anat Rec, 300:1519-1523, 2017. © 2017 Wiley Periodicals, Inc.


Sujet(s)
Dauphins/anatomie et histologie , Spermatozoïdes/cytologie , Spermatozoïdes/ultrastructure , Animaux , Mâle , Microscopie électronique à balayage
3.
Bioorg Med Chem Lett ; 27(8): 1780-1783, 2017 04 15.
Article de Anglais | MEDLINE | ID: mdl-28274634

RÉSUMÉ

We report the synthesis of two new artificial nucleobase scaffolds, 1 and 2, featuring adequate hydrogen bonding donors and acceptors for the molecular recognition of U:A and C:G base pairs, respectively. The tethering of these structures to various amino acids and the assessment of these artificial nucleobase-amino acid conjugates as RNA ligands against a model of HCV IRES IIId domain are also reported. Compound 1e displayed the highest affinity (Kd twice lower than neomycin - control). Moreover, it appears that this interaction is enthalpically and entropically favored.


Sujet(s)
Régions 5' non traduites/effets des médicaments et des substances chimiques , Acides aminés/pharmacologie , Antiviraux/pharmacologie , Hepacivirus/effets des médicaments et des substances chimiques , Purines/pharmacologie , Pyrimidines/pharmacologie , ARN viral/métabolisme , Acides aminés/composition chimique , Antiviraux/composition chimique , Appariement de bases/effets des médicaments et des substances chimiques , Séquence nucléotidique , Hepacivirus/composition chimique , Hepacivirus/métabolisme , Hépatite C/traitement médicamenteux , Hépatite C/virologie , Humains , Ligands , Conformation d'acide nucléique , Purines/composition chimique , Pyrimidines/composition chimique , ARN viral/composition chimique
4.
Tech Hand Up Extrem Surg ; 20(4): 155-160, 2016 Dec.
Article de Anglais | MEDLINE | ID: mdl-27801774

RÉSUMÉ

Locked volar plating is the most common surgical procedure to address distal radius fractures. The extended flexor carpi radialis approach continues to be an excellent method for visualizing distal radius fractures and applying a volar plate. A new understanding of the anatomy allows for better visualization and reduction of the many different distal radius fracture patterns surgeons commonly see. Within the extended flexor carpi radialis approach, we describe the radial septum in further detail including the anatomy which comprises the radial septum triangle. Knowledge of this area allows for better visualization, more anatomic reductions, and fewer complications.


Sujet(s)
Plaques orthopédiques , Dissection/méthodes , Ostéosynthèse interne/méthodes , Plaque palmaire , Fractures du radius/chirurgie , Tendons/chirurgie , Humains , Sélection de patients
5.
PLoS One ; 9(1): e83623, 2014.
Article de Anglais | MEDLINE | ID: mdl-24465386

RÉSUMÉ

True river dolphins are some of the rarest and most endangered of all vertebrates. They comprise relict evolutionary lineages of high taxonomic distinctness and conservation value, but are afforded little protection. We report the discovery of a new species of a river dolphin from the Araguaia River basin of Brazil, the first such discovery in nearly 100 years. The species is diagnosable by a series of molecular and morphological characters and diverged from its Amazonian sister taxon 2.08 million years ago. The estimated time of divergence corresponds to the separation of the Araguaia-Tocantins basin from the Amazon basin. This discovery highlights the immensity of the deficit in our knowledge of Neotropical biodiversity, as well as vulnerability of biodiversity to anthropogenic actions in an increasingly threatened landscape. We anticipate that this study will provide an impetus for the taxonomic and conservation reanalysis of other taxa shared between the Araguaia and Amazon aquatic ecosystems, as well as stimulate historical biogeographical analyses of the two basins.


Sujet(s)
Biodiversité , Dauphins/croissance et développement , Dauphins/génétique , Espèce en voie de disparition , Animaux , Brésil , Cytochromes b/génétique , ADN mitochondrial/composition chimique , ADN mitochondrial/génétique , Dauphins/classification , Complexe IV de la chaîne respiratoire/génétique , Variation génétique , Géographie , Répétitions microsatellites/génétique , Données de séquences moléculaires , Phylogenèse , Analyse en composantes principales , Rivières , Analyse de séquence d'ADN
6.
Genetica ; 140(7-9): 307-15, 2012 Sep.
Article de Anglais | MEDLINE | ID: mdl-23010983

RÉSUMÉ

Classical and molecular cytogenetic (18S rDNA, telomeric sequence, and LINE-1 retrotransposon probes) studies were carried out to contribute to an understanding of the organization of repeated DNA elements in the Amazon River dolphin (boto, Inia geoffrensis). Twenty-seven specimens were examined, each presenting 2n = 44 chromosomes, the karyotype formula 12m + 14sm + 6st + 10t + XX/XY, and fundamental number (FN) = 74. C-positive heterochromatin was observed in terminal and interstitial positions, with the occurrence of polymorphism. Interstitial telomeric sequences were not observed. The nucleolar organizer region (NOR) was located at a single site on a smallest autosomal pair. LINE-1 was preferentially distributed in the euchromatin regions, with the greatest accumulation on the X chromosome. Although the karyotype structure in cetaceans is considered to be conserved, the boto karyotype demonstrated significant variations in its formula, heterochromatin distribution, and the location of the NOR compared to other cetacean species. These results contribute to knowledge of the chromosome organization in boto and to a better understanding of karyoevolution in cetaceans.


Sujet(s)
Dauphins/génétique , Animaux , Cytogénétique , ADN ribosomique/génétique , Euchromatine/génétique , Euchromatine/métabolisme , Caryotypage , Organisateur nucléolaire/génétique , Rivières
SÉLECTION CITATIONS
DÉTAIL DE RECHERCHE