1,721,088 research outputs found
The need for genetic support in restocking activities andex situconservation programmes: the case of the Adriatic sturgeon (Acipenser naccariiBonaparte, 1836) in the Ticino River Park
No full textThe Adriatic sturgeon (Acipenser naccarii Bonaparte, 1836), endemic to the North Adriatic region, was recently reclassified by IUCN as 'Critically endangered and possibly extinct in the wild' since no natural spawning has been recorded in the last 20 years. Its survival relies on restocking activities originating from a single captive broodstock collected by a private aquaculture plant (V.I.P.) in the 1970s and is currently reduced to 13 individuals. Few alternative brood-stocks of F1 animals have been retained for use in the near future. Thus far, brood-stocks, as well as all stocks released in the wild, have been randomly chosen without regard to their genetic composition. The consequence of breeding programmes with no genetic input was evaluated in the Ticino River Park (TRP) in Italy. A parental allocation procedure based on microsatellite markers useful for tetraploids was used following a Band-Sharing approach. Levels of relatedness within the TRP F1 captive breeders (Stock_1) and among animals released by TRP in the past (Stock_2) were explored and compared with the stock of wild origin. The pronounced decrease in genetic diversity observed in the analysed sample suggests the need for complete reorganization and coordination of conservation efforts for this species, paying particular attention to the long-term preservation of the genetic diversity. Also identified is the only potentially suitable stock of F1 animals that should be used as source of future breeders
Isolation of microsatellite loci from the endemic and endangered Adriatic sturgeon (Acipenser naccarii).
No full textWith the aim of elaborating a breeding plan on a captive stock of the highly endangered Adriatic sturgeon (Acipenser naccarii), a total of 10 polymorphic microsatellite loci were isolated from an enriched library. The results of cross amplification of additional 8 loci previously isolated from A. oxyrinchus, A. fulvescens and Scaphyrinchus platorhynchus are also reported. Given the tetraploid condition of the species the genetic variability was estimated basing on the number of alleles per individuals and the average band sharin
Life cycle of Cyathocephalus truncatus (Cestoda: Spathebothridea) parasite of fish by use of molecular techniques
No full textMorphological identification of tapeworm species at larval stages (procercoids and cysticercoids) is often difficult because few diagnostic characters are available. In the present study, a molecular approach (sequencing of partial I SS rDNA gene) was used to evaluate the genetic similarity between adult specimens of Cyathocephalus truncatus (Pallas, 1871) (Cestoda: Spathebothriidea) found in fish. its definitive host, and procercoids of the same species recovered from amphipod, Echinogammarus stammeri (Karaman. 1931). Furthermore, cestode cysticercoids of uncertain species were found in the amphipod's hemocoel. The sequences obtained from adults and procercoids were identical. and even very similar to those of C. truncatus available in GenBank, whereas the sequences obtained from cysticercoids differed significantly from those of adults and procercoids, indicating that these larvae belong to another species; later it was demonstrated that they were cysticercoids of Microsomacanthus pachycephala (Linstow, 1972), a cestode of the Hymenolepididae (Cyclophyllidea). The results of this investigation show that the comparison of nucleotide sequence data may avoid misclassification of developmental stages of parasites, which use the same intermediate host
Population analysis of the sand smelt Atherina boyeri Risso, 1810 (Teleostei Atherinidae) from Italian coastal lagoons by Random Amplified Polymorphic DNA (RAPD-PCR)
No full textAtherina boyeri Risso, 1810 is a euryhaline species of ecological and economic relevance, highly diffused in most Mediterranean coastal lagoons and characterized by high morphological variability among populations. To study the genetic relationships among A. boyeri populations, 11 Italian lagoons and 2 freshwater lakes were sampled and a random amplified polymorphic DNA analysis was performed. Six arbitrarily designed primers were used. Of the 43 scored markers, 39 were polymorphic. No population-specific markers were found. Statistical analysis based on inferred allele frequencies (using Wright's F(st) statistic) and on presence or absence of bands (using analysis of molecular variance) revealed significant population structure. Unweighted pair group method with arithmetic mean cluster analysis based on Nei's genetic distances showed a geographic clustering of populations. Mantel tests confirmed a high correlation between genetic and geographic distances along coasts. These results suggest the occurrence of coastal gene flows among populations, probably because the anadromic behavior of this species may be only partially phylopatric. However, these migratory movements have not blurred the existing differences among populations
Sturgeon genetics and cytogenetics: recent advancements and perspectives
No full textThe aim of this review is to introduce current knowledge in the field of sturgeon genetics. The first section deals with sturgeon cytogenetics, reviewing karyotype organization and polyploidization events during evolution of Acipenseriformes. The second section concerns the results of applications of molecular biology to studies of phylogenetic relationships between extant species, intraspecific analysis of wild populations and stocks for conservation purposes, together with characterization of molecular markers for species identification, relevant to forensic and conservation issues
Phylogenetic relationships and demographic histories of the Atherinidae in the Eastern Atlantic and Mediterranean Sea re-examined by Bayesian inference
No full textThe aim of our study is to examine the phylogenetic relationship, divergence times and demographic history of the five close-related Mediterranean and North-eastern Atlantic species/forms of Atherina using the full Bayesian framework for species tree estimation recently implemented in ∗BEAST. The inference is made possible by multilocus data using three mitochondrial genes (12S rRNA, 16S rRNA, control region) and one nuclear gene (rhodopsin) from multiple individuals per species available in GenBank. Bayesian phylogenetic analysis of the complete gene dataset produced a tree with strong support for the monophyly of each species, as well as high support for higher level nodes. An old origin of the Atherina group was suggested (19.2 MY), with deep split events within the Atherinidae predating the Messinian Salinity Crisis. Regional genetic substructuring was observed among populations of A. boyeri, with AMOVA and MultiDimensional Scaling suggesting the existence of five groupings (Atlantic/West Mediterranean, Adriatic, Greece, Black Sea and Tunis). The level of subdivision found might be consequence of the hydrographic isolation within the Mediterranean Sea. Bayesian inference of past demographic histories showed a clear signature of demographic expansion for the European coast populations of A. presbyter, possibly linked to post-glacial colonizations, but not for the Azores/Canary Islands, which is expected in isolated populations because of the impossibility of finding new habitats. Within the Mediterranean, signatures of recent demographic expansion were only found for the Adriatic population of A. boyeri, which could be associated with the relatively recent emergence of the Adriatic Sea
The use of bird feathers for the monitoring of cadmium pollution
No full textThe cadmium contamination mechanism in bird feathers was investigated using starlings fed with diets containing 10 and 50 ppm Cd for five months. The experiment started about two months before the beginning of the annual complete feather molt and lasted until most of the birds completed the molt of the primaries. Concentrations of Cd in liver, kidney, and uropygial gland were highly correlated, but uropygial gland concentration was about 100 times lower. Cadmium was found both in old and new feathers, in a dose-related manner. Old feathers showed higher metal concentrations than new ones and primaries higher than secondaries. Feather Cd concentration correlated with Cd concentration in liver, kidney, and the uropygial gland. The use of bird feathers are, therefore, a reliable method for monitoring cadmium pollution, but differences between feather type and age must be considered to correctly interpret data collected in the field
Spatial variability of the Po River food web and its comparison with the Danube River food web
Full text linkFreshwater ecosystems are experiencing unprecedented pressure globally. To address environmental challenges, systematic and comparative studies on ecosystems are needed, though mostly lacking, especially for rivers. Here, we describe the food web of the Po River (as integrated from the white literature and monitoring data), describe the three river sections using network analysis, and compare our results with the previously compiled Danube River food web. The Po River food web was taxonomically aggregated in five consecutive steps (T1-T5) and it was also analyzed using the regular equivalence (REGE) algorithm to identify structurally similar nodes in the most aggregated T5 model. In total, the two river food webs shared 30 nodes. Two network metrics (normalized degree centrality [nDC]) and normalized betweenness centrality [nBC]) were compared using Mann-Whitney tests in the two rivers. On average, the Po River nodes have larger nDC values than in the Danube, meaning that neighboring connections are better mapped. Regarding nBC, there were no significant differences between the two rivers. Finally, based on both centrality indices, Carassius auratus is the most important node in the Po River food web, whereas phytoplankton and detritus are most important in the Danube River. Using network analysis and comparative methods, it is possible to draw attention to important trophic groups and knowledge gaps, which can guide future research. These simple models for the Po River food web can pave the way for more advanced models, supporting quantitative and predictive-as well as more functional-descriptions of ecosystems
The use of AFLP in sturgeon identification
No full textIn this study a multilocus approach through Amplified Fragment Length Polymorphism (AFLP) was applied to species identification of sturgeon commercial products ( meat and caviar) and to identification of interspecific hybrids. Species identification of commercial products was simply performed by comparison of electrophoretic profiles with those of referring species. Concerning interspecific hybrids, the simultaneous occurrence of the diagnostic bands fixed in the parental species and a cluster analysis on both fixed and polymorphic bands allowed a correct identification. The results strongly suggest that this technique is highly suitable for analysis of market products as well as precise identification of species and interspecific hybrids
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