65 research outputs found
Extension of Wavenumber Domain Focusing for spotlight COSMO-SkyMed SAR Data
In this work we describe a method to handle curved orbits in wavenumber domain focusing algorithm for high-resolution SAR data acquired by Low Earth Orbit satellites using spotlight mode. The stand..
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
Cytogenetical and morphological features reveal significant differences among Venezuelan and Brazilian samples of Mugil curema (Teleostei: Mugilidae)
Karyotype characterization of Mugil incilis Hancock, 1830 (Mugiliformes: Mugilidae), including a description of an unusual co-localization of major and minor ribosomal genes in the family
Chromosomal location of 18S and 5S rDNA sites in Triportheus fish species (Characiformes, Characidae)
Cytogenetic studies in three species of Lutjanus (Perciformes: Lutjanidae: Lutjaninae) from the Isla Margarita, Venezuela
Cytogenetic analysis of three sea catfish species (Teleostei, Siluriformes, Ariidae) with the first report of Ag-NOR in this fish family
Despite their ecological and economical importance, fishes of the family Ariidae are still genetically and cytogenetically poorly studied. Among the 133 known species of ariids, only eight have been karyotyped. Cytogenetic analyses performed on Genidens barbus and Sciades herzbergii revealed that both species have 2n = 56 chromosomes and Cathorops aff. mapale has 2n = 52 chromosomes: Genidens barbus has 10 Metacentrics (M), 14 Submetacentrics (SM), 26 Subtelocentrics (ST), and 6 Acrocentrics (A), Sciades herzbergii has 14M, 20SM, 18ST and 4A, whereas Cathorops aff. mapale has 14M, 20SM, and 18ST. The nucleolus organizer regions (NORs) were found in a single chromosome pair on the short arm of a large-sized ST pair in Genidens barbus and on the short arm of a middle-size SM pair in Cathorops aff. mapale. Multiple NORs on the short arms of two large-sized ST pairs were found in Sciades herzbergii. The occurrence of diploid numbers ranging from 2n = 52 through 56 chromosomes and the presence of different karyotypic compositions, besides the number and position of NORs suggest that several numeric and structural chromosome rearrangements were fixed during the evolutionary history of this fish family
First Evidence of Immunomodulation in Bivalves under Seawater Acidification and Increased Temperature
Water acidification, temperature increases and changes in seawater salinity are predicted to occur in the near future. In such a global climate change (GCC) scenario, there is growing concern for the health status of both wild and farmed organisms. Bivalve molluscs, an important component of coastal marine ecosystems, are at risk. At the immunological level, the ability of an organism to maintain its immunosurveillance unaltered under adverse environmental conditions may enhance its survival capability. To our knowledge, only a few studies have investigated the effects of changing environmental parameters (as predicted in a GCC scenario) on the immune responses of bivalves. In the present study, the effects of both decreased pH values and increased temperature on the important immune parameters of two bivalve species were evaluated for the first time. The clam Chamelea gallina and the mussel Mytilus galloprovincialis, widespread along the coast of the Northwestern Adriatic Sea, were chosen as model organisms. Bivalves were exposed for 7 days to three pH values (8.1, 7.7 and 7.4) at two temperatures (22 and 28°C). Three independent experiments were carried out at salinities of 28, 34 and 40 PSU. The total haemocyte count, Neutral Red uptake, haemolymph lysozyme activity and total protein levels were measured. The results obtained demonstrated that tested experimental conditions affected significantly most of the immune parameters measured in bivalves, even if the variation pattern of haemocyte responses was not always linear. Between the two species, C. gallina appeared more vulnerable to changing pH and temperature than M. galloprovincialis. Overall, this study demonstrated that climate changes can strongly affect haemocyte functionality in bivalves. However, further studies are needed to clarify better the mechanisms of action of changing environmental parameters, both individually and in combination, on bivalve haemocytes
Molecular and cytogenetic analyses of cryptic species within the Synbranchus marmoratus Bloch, 1795 (Synbranchiformes: Synbranchidae) grouping: species delimitations, karyotypic evolution and intraspecific diversification
PRELIMINARY MODEL FOR WIND ESTIMATION FROM COSMO/SKYMED X BAND SAR DATA
In the paper we present a preliminary model for wind estimation from SAR data in X band. The data set we have used is composed of more than 300 Cosmo/SkyMed SAR images and the wind data obtained from the SeaWinds instrument on QuikSCAT. We have derived 18 parameters to express sigma(o) as function of wind intensity, direction and Radar look angle. The preliminary validation results are encouraging although our data set needs to be extended in order to increase those conditions poorly represented
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