Étude moléculaire des populations de Rhodiola rosea L. du nunavik (Québec, Canada)

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Résumé des connaissances actuelles sur la biologie et la pêche des thons tropicaux en Atlantique

This work summarizes the present knowledge on biology and fisheries of Atlantic tuna such as yellowfin (Thunnus albacares), skipjack (Katsuwonus pelamis) and to a lesser extent, bigeye (Thunnus obesus) and albacore (Thunnus alalunga). Current appraisal of these stocks

Peuplements zooplanctoniques dans les régions de remontées d'eau du littoral atlantique africain

The introduction is followed by a resume of the biogeographic factors and the principal work. The characteristics of zooplankton in different regions are presented based on regular research in Santa Helena Bay and Walvis Bay and the research carried out by William Scoresby. Certain factors of the digestive system of South African plankton are discussed. The next section concerns research in intertropical and equatorial regions in the Gulf of Guinea. It considers the littoral region of Angola, the Pointe Noire region and discusses the density and complexity of stocks. The last section concerns the zooplankton of Nigeria, Ghana and the Ivory Coast and discusses the grouping of species and compares the results.

Croissance du patudo (Thunnus obesus) de l'Océan Atlantique intertropical oriental

The growth of big eye tuna (Thunnus obesus) in the Eastern Tropical Atlantic Ocean was studied using Petersen's method, by the analysis of the length frequency data of the F.I.S. (French-Ivorian-Senegalese) surface tuna fleet from 1969 to 1977. The results are in agreement with a previous study by Champagnat and Pianet (1973) and with observations made in the Pacific Ocean.

Excrétion organique du phytoplancton et activité bacterienne hétérotrophe dans le Dôme de Guinée (Océan Atlantique Tropical Est)

Primary production rates in the Gulf the Guinea (east tropical Atlantic) were measured with in situ incubations. The extracellular organic carbon passed through 0.8 u pore size membrane filters averaged 29.5% of the carbon fixed by photosynthesis. These is a good linear correlation (r=0.86) between assimilation and organic excretion. The significance and limits of the method for the measurements of low rates of photosynthesis is discussed. The influence of ecological factors (nutrients, light and stability) cannot be demonstrated. The importance of bacterial regeneration processes by reutilization of algal extracellular products is assessed.

Récolte et traitement des données statistiques de la pêche des palangriers asiatiques dans l'Atlantique

The authors report on the computer programmes developed in the Oceanographic Research Centre of Abidjan for the collection and treatment of statistical data on the fisheries of the asiatic trawlers in the Atlantic. They provide yield by boat, by fishing sector (5 degrees x 5 degrees) and by 15 days fishing in the Atlantic.

Circulation dans la partie orientale de l'Atlantique sud

The authors studied the circulation in the South Tropical Atlantic from hydrology and current measurements made during a cruise of the N.O. Capricorne in Nov 1971. Direct current measurements confirm the existence of the eastwards South Equatorial Counter-Current. The authors discuss the counter-current as confirmed by current measurements and high salinity core.

Recherches des larves de thonides dans l'Atlantique tropical-oriental: campagnes effectuées en 1976-1977 par le N/O Capricorne

This study gives the results of oblique plankton hauls (from the sea-surface to the top of the thermocline), made during the dry season (January to March) by oceanographic vessel R.V. Capricorne during three cruises, of tuna larvae research in 1976 and 1977, between the African Coast and the Equator, from 17 degrees W to 9 degrees E.

Distribution et abondance des larves de thonidés dans l'Atlantique tropico-oriental. Étude des données de 1963 à 1974

From several sources of data, the authors study seasonal variations of larval abundance for five species of tuna in Eastern Tropical Atlantic and its relation to the hydrological conditions. Distributional maps and TS graphs are given.

Biomasses du phytoplancton et du zooplancton dans l'Atlantique tropical le long du méridien 1O' W (Résultats de la campagne Capricorne 7314)

The standing stock of chlorophyll, the quantities of copepods collected with a 30 liter Niskin bottle and the standing stock of zooplankton collected with a 'Bongo' net were measured from 0 to 200 m depth during a cruise along 10' W from 1' N to 12' S. These parameters are correlated to hydrological conditions measured simultaneously. 6 zonal areas have been delimited and described; the north equatorial convergence, the northern flow of the south equatorial counter-current, the trade winds drift, the south equatorial counter-current and the Benguela's drift.

Construction of a BAC library for Chinese amphioxus Branchiostoma belcheri and identification of clones containing Amphi-pax genes

Amphioxus is a crucial organism for the study of vertebrate evolution. Although a genomic BAC library of Branchiostoma floridae has been constructed, we report here another BAC library construction of its distant relative species Branchiostoma belcheri. The amphioxus BAC library established in present study consists of 45,312 clones arrayed in one hundred and eighteen 384-well plates. The average insert fragment size was 120 kb estimated by Pulsed Field Gel Electrophoresis (PFGE) analysis of 318 randomly selected clones. The representation of the library is about 12 equivalent to the genome, allowing a 99.9995% probability of recovering any specific sequence of interest. We further screened the library with 4 single copied Amphi-Pax genes and identified total of 26 positive clones with average of 6.5 clones for each gene. The result indicates this library is well suited for many applications and should also serve as a useful complemental resource for the scientific community.

Amphi-Eomes/Tbr1: An amphioxus cognate of vertebrate Eomesodermin and T-Brain1 genes whose expression reveals evolutionarily distinct domain in amphioxus development

A cDNA for a novel T-box containing gene was isolated from the amphioxus Branchiostoma belcheri. A molecular phylogenetic tree constructed from the deduced amino acid sequence of the isolated cDNA indicates that this gene belongs to the T-Brain subfamily. In situ hybridization reveals that the expression is first detected in the invaginating archenteron at the early gastrula stage and this expression is down-regulated at the neurula stage. In early larvae, the expression appears again and transcripts are detected exclusively in the pre-oral pit (wheel organ-Hatschek's pit of the adult). In contrast to the vertebrate counterparts, no transcripts are detected in the brain vesicle or nerve cord throughout the development. These results are interpreted to mean that a role of T-Brain products in vertebrate forebrain development was acquired after the amphioxus was split from the lineage leading to the vertebrates. On the other hand, comparison of the tissue-specific expression domain of T-Brain genes and other genes between amphioxus and vertebrates revealed that the pre-oral pit of amphioxus has several molecular features which are comparable to those of the vertebrate olfactory and hypophyseal placode. (C) 2002 Wiley-Liss, Inc.

L'influence atlantique dans les montagnes portugaises au sud duTage

Prenant la flore et la végétation comme des indicateurs du climat local, on fait une analyse abrégée de l'influence atlantique sur quatre montagnes portugaises, s¡tuées au sud du fleuve Tage, en plain domaine méditerranéen. Elles sont distríbuées depuis le nord-est de l‘Alentejo jusqu’a l’extreme sud-ouest du territoire.L'observation des données floristiques a montré que la dominance des espéces méditerrennes est générale, bien que entre un mínimum de 34.0% à S. Mamede et un maximum de 48.9 % à Portel. On a vérifié aussi, en commun, un trés faible degré d'endémisme, lequel atteint la valeur la plus élevée -1.2%-, dans la montagne de Monchique. 

Contribution à l’étude du nannoplacton du leg 12, «sites» 118-119 (Ocean Atlantique)

This paper reports a Scanning Electron Microscopy study of some samples from the leg 12, Deep Sea Drilling Project, sites 118 and 119. The chronostratigraphic distribution, the frequency of the species identified and the datation of the samples studied are presented. In accordance with the calcareous nannofossil zonation proposed by E. MARTINI (1971) the samples from site 118 are ascribed to the Upper Miocene while the samples from site 119 are located between the Lower (NN1) and the Upper Miocene (NN10).

Analyse paléoécologique des formations récifales du golfe de Skoura (bordure méridionale du sillon Sud rifain; SE de Fés; Maroc) implications paléogéographiques: communications Atlantique - Méditerranée au Miocène Terminal

The reef levels of the gulf of skoura belong to the reef formation of the Upper Miocene of the South-Rifan straits. A detailed analysis of the vertical distribution of various forms of colonies has led to the establishment of precise coral morphologies zonation. This palaeoecological approach leads us to distinguish between two environments in the Skoura gulf, probably corresponding to two reef episodes. The palaeogeographical implications (relationships between the Atlantic ocean and the Mediterranean sea) will be pointed out.