Chromosome evolution in fishes: a new challenging proposal from Neotropical species

We present a database containing cytogenetic data of Neotropical actinopterygian fishes from Venezuela obtained in a single laboratory for the first time. The results of this study include 103 species belonging to 74 genera assigned to 45 families and 17 out of the 40 teleost orders. In the group of marine fishes, the modal diploid number was 2n=48 represented in 60% of the studied species, while in the freshwater fish group the modal diploid complement was 2n=54, represented in 21.21 % of the studied species. The average number of chromosomes and the mean FN were statistically higher in freshwater fish than in marine fish. The degree of diversification and karyotype variation was also higher in freshwater fish in contrast to a more conserved cytogenetic pattern in marine fish. In contrast to the assumption according to which 48 acrocentric chromosomes was basal chromosome number in fish, data here presented show that there is an obvious trend towards the reduction of the diploid number of chromosomes from values near 2n=60 with high number of biarmed chromosomes in more basal species to 2n=48 acrocentric elements in more derived Actinopterygi

Une nouvelle espèce africaine du genre \u3cem\u3eStenasellus\u3c/em\u3e (\u3cem\u3eCrustacea Isopoda Asellota\u3c/em\u3e) du bassin du Niger

The representatives of the genus Stenasellus (sensu lato) in Africa have been previously known from Cote d’lvoire, bassin of the Congo and Somali. The new species of this genus was collected from the well in the town Sicascau (Mali). This species differs from all others in the structure of the carpopodites of pereopods II-IV which are enlarged and armed with multiple curved spines. This character shows a distinct sexual dimorphism. In all other features St. laticarpus sp.n. belongs to the group of St. gjorgjevici Rac. and shows the closest resemblance to St. africanus Monod. It is now preferable to conserve the unity of the genus Stenasellus (sensu lato). The validity of the African endemic genera Metastenasellus Magniez, Parastenasellus Magniez and Magniezia Lanza needs to be confirmed

Faune des eaux souterraines saumâtres de l\u27Asie Centrale

In the cave Kaptar-Khana (south-western Turkmenistan) was discovered a lake filled with water with a salinity of 11,68‰. This lake is inhabited by a fauna of marine origin - Foraminifera (three species), Molluscs (Pseudocaspia ljovuschkini sp.n.), Harpacticoida (genera Ectinosoma, Schizopera and Nitocra), Isopoda (Microcharon halophilus sp.n.) and possibly Nematoda (Oncholaimidae). The majority of the discovered species are related to species of circum-Mediterranean origin. Geological data do not permit to consider this fauna as a relict of any of the tertiary seas. The same applies to all other cases when animals of marine origin were discovered in subterranean waters of Central Asia (as for instance Microcharon kirghisicus Jank. on the shores of the lake Issyk-Kul). We can either admit a far greater anciennity of this fauna or an ability of its components to disperse very widely beyond the boundaries of marine transgressions

Faune des eaux souterraines saumâtres de l\u27Asie Centrale

In the cave Kaptar-Khana (south-western Turkmenistan) was discovered a lake filled with water with a salinity of 11,68‰. This lake is inhabited by a fauna of marine origin - Foraminifera (three species), Molluscs (Pseudocaspia ljovuschkini sp.n.), Harpacticoida (genera Ectinosoma, Schizopera and Nitocra), Isopoda (Microcharon halophilus sp.n.) and possibly Nematoda (Oncholaimidae). The majority of the discovered species are related to species of circum-Mediterranean origin. Geological data do not permit to consider this fauna as a relict of any of the tertiary seas. The same applies to all other cases when animals of marine origin were discovered in subterranean waters of Central Asia (as for instance Microcharon kirghisicus Jank. on the shores of the lake Issyk-Kul). We can either admit a far greater anciennity of this fauna or an ability of its components to disperse very widely beyond the boundaries of marine transgressions

Symposium on conservation of the Atlantic sturgeon Acipenser sturio L. 1758 in Europe

International audienceThe symposium was organised by the Department of Animal biology I of Madrid's complutense university and the society to save the sturgeon. More than forty delegates from France, Germany, Greece, Hungary, Poland, Portugal, Romania, Russia, Slovakia, Spain, Ukraine and the USA attented and contributed to the scientific discussions during the sessions. The main objectives of the Symposium were to bring together those concerned with or working on conservation of A. sturio, and to produce a book of proceedings, including an overview of the present knowledge on the subject

Adsorption of nitrogen tetroxide on silica gel /

Work performed at the Air Reduction Sales Company.Includes bibliographic references."August 31, 1949""AECU-438, (ARSC-30)"Mode of access: Internet