1,721,170 research outputs found
Premessa
No full textPremessa al volume "Fondamenti di diritto contrattuale europeo. Dalle radici romane al Draft Common Frame of Reference, II, Materiali e commento", a cura di G. Luchetti - A. Petrucc
Premessa
No full textIntroduzione al volume "Fondamenti romanistici del diritto europeo. Le obbligazioni e i contratti dalle radici romane al Draft Common Frame of Reference", a cura di G. Luchetti - A. Petrucc
Evolutionary genomics of the crustacean Triops cancriformis (Branchiopoda, Notostraca)
No full textWHO? Triops cancriformis is a crustacean of the class Branchiopoda, order Notostraca. The order comprises only two genera (Triops and Lepidurus) world-wide distributed owing to their ancient origin. T. cancriformis lives in freshwater ponds that may be subjected to dry period during which the tadpole shrimps survive as encysted egg resistant stages. It is also well known for
its high morphological stasis, compared with fossil forms; hence
the debated status of "living fossil". WHY? Aside from the peculiar morphological stasis, T. cancriformis represents an interesting framework to address evolutionary studies: i) across its European range it is present with bisexual, parthenogenetic, hermaphroditic and androdioecious populations: it would be, thus, interesting to check whether di erent reproductive strategies leave genomic signatures such as di erential evolutionary rates and/or trans- posable element accumulation; ii) Branchiopod crustaceans are phylogenetically close to Hexapoda, in most analyses resulting
their sister clade. The study of T. cancriformis genomic features
in comparison with those of early-branching Hexapoda could tell about the origin of hexapods and their most represented taxon, Insecta. HOW? Genomic resources on T. cancriformis and related species are slowly accumulating (transcriptomes, RAD-sequencing and one genome draft), although a comprehensive and co-or- dinated project of a genomic evolutionary study is still lacking.
We therefore, undertaken Illumina sequencing of T. cancriformis genomes, starting from Italian parthenogenetic samples and Spanish bisexual ones. Moreover, we included two species from the related genus Lepidurus (L. apus lubbocki and L. arcticus) in order to have a clearer picture of Notostraca genomes. Further sequencing will be performed on transcriptome and already published data will be also included in the analyses. TO GET WHAT? A total evidence picture on the hardwares (genomes) and softwares (transcriptomes) evolution, with a special focus on repetitive DNA (transposable elements and satellite DNA), in the same species presenting genomes subject to di erent reproductive milieau. We have already some results indicating that transposable elements (R2 lineages) are di erently evolving in di erent T. cancriformis genomes. The full genome sequencing of further population/ species will help drawing a more complete picture, including the possibility to study all transposable element lineages as well as satellite DNAs. Moreover, the strengthening of the genomic dataset with new branchiopod species will likely result in a more stable phylogenetic relationship of Branchiopoda with closer taxa. Finally, we will get knowledge on the genome structure and composition that will be compared with the close relatives, the Hexapoda
Molecular and morphometrical characterization of Sicilian Reticulitermes termites (Blattodea, Termitoidae, Rhinotermitidae) with the description of a new subspecies
No full textThe subterranean termite Reticulitermes lucifugus (Rossi 1792) is distributed in Italy and southern France, both in natural and urban environments. It comprises three lineages: i) R. lucifugus lucifugus (Rossi 1792) in the mainland, ii) R. lucifugus corsicus Clement 1977 in Corsica, Provence, Sardinia and a portion of the Tyrrhenian coast of Italy, iii) a third lineage, not yet described, identified based on the genetic analysis of a few samples from Sicily and from an isolated population in northern Italy, where it was most probably introduced by man. In this study, we characterize genetically (COII and 16S mitochondrial genes) and morphometricall y (measurements of alates and soldiers) the Sicilian lineage, based on new samples collected all over the island. Our results confirm the existence of a well supported clade comprising all the samples from Sicily, neatly separated from R. lucifugus lucifugus and R. lucifugus corsicus. No other Reticulitermes species or subspecies was found in Sicily, and the Sicilian lineage was not found in peninsular Italy, suggesting that the strait separating Sicily from the mainland is an effective barrier to termite dispersal. Based on these results, we describe the Sicilian lineage of R. lucifugus as Reticulitermes lucifugus siculus ssp. nov. Zoobank registration: urn:lsid:zoobank.org:pub:AECFCF35-156C-4169-8DAC-0B7F510E754D
Mitochondrial phylogenomics supports a Carboniferous origin of Xenonomia
No full textPolyneoptera includes some of the best-known insect species, such as grasshoppers and cockroaches. While the evolutionary history of many Polyneoptera orders has been thoroughly explored, others have been partially overlooked. This is the case with Xenonomia, a clade consisting of two species-poor insect orders with a relatively recent taxonomic history: Mantophasmatodea and Grylloblattodea. Here, we provide a temporal framework for their evolution, leveraging a mitochondrial phylogenomics approach encompassing all Polyneoptera orders. To strengthen the confidence in our divergence times estimation, we specifically focused on the possible impact of phylogenetic biases, such as long branch attraction, the influence of specific fossil priors, the use of nucleotide or amino acid alignments, and different clock models. Our results consistently support the origin of Xenonomia during the Carboniferous, and the divergence between the two orders is inferred to have happened before the Permian. While Grylloblattodea diversification is inferred to have occurred earlier than that of Mantophasmatodea, extant species of both orders most likely diversified after the Permian/Triassic and Triassic/Jurassic mass extinctions. Our molecular divergence time analyses complement the fossil record and support the ancient relict status of these two polyneopteran orders
Epilepsy, electroencephalographic abnormalities, and regression in children with autism
No full textThe association of epilepsy and autism is recognized, and it has been reported at a percentage that varies between 8 and 42%, depending on age and diagnostic criteria. One third of autistic children undergo a regression of language and behavior between 2 and 3 years, and epileptiform abnormalities and epilepsy can be concomitant in an undetermined percentage of them. The aim of this study was to investigate the prevalence of epilepsy and paroxysmal abnormalities in a group of children with autism and to determine the percentage of regression course in this group. Forty-six patients with autism (mean age 7.8 +/- 2.7 years; 34 boys and 12 girls) were consecutively examined, and clinical evaluation, assessment, and electroencephalographic (EEG) recordings were performed in all of them. Thirty-five percent showed paroxysmal abnormalities and epilepsy, 22% had only paroxysmal abnormalities without seizures, and 13% of the children suffered from epilepsy. Sixty-five percent had a normal EEG. No difference in regression rate was observed between patients with paroxysmal abnormalities and epilepsy and those with a normal EEG and without seizures. In the study group, the prevalence of epilepsy was in the low range of individuals with autism, and different types of epilepsy were observed. Autism with regression was not influenced by paroxysmal abnormalities and epilepsy
Phylogeography and colony structure of dry-wood dwelling termites of the genus Kalotermes (Isoptera, Kalotermitidae) in Southern Europe
No full textAccording to the most recent phylogenetic and phylogeographic investigations, the Kalotermes genus (Kalotermitidae) includes three different mitochondrial lineages of K. flavicollis and the new K. italicus species. In some Italian populations extreme colony fusion events were observed, with mixed families composed by up to nine maternal lines belonging to different genetic lineages or even to different species. In termites with the same nesting type, colony fusions lead to the death of queens and kings allowing false workers (pseudoergates) to evolve into reproducers and to inherit the colony (Accelerated Nest Inheritance). To widen the analyses on Kalotermes phylogeography and colony structure, we sequenced 912 bp of the mitochondrial genome, corresponding to COI/tRNA-Leu/COII, in two individuals from each of the 21 colonies collected in 11 European localities. In four colonies showing haplotypes of different genetic lineages/species, five-eight individuals per colony were further analyzed. A more detailed biogeographic scenario is obtained, with overlapping distribution areas of the considered lineages/species. Moreover, data confirm that mixed colonies with haplotypes of different genetic lineages/species may show more than two maternal lines. On the whole, colony fusions appear to occur more frequently than expected on the basis of eusociality models. Moreover, the possibility of hybridization between different genetic lineages or species could facilitate the fusion of more than two colonies wiping out mechanisms of nest-mate recognition. This analysis, therefore, demonstrates that dry-wood dwelling termites might be an interesting framework to study the evolution and maintenance of eusociality
Exploring mitogenome evolution in Branchiopoda (Crustacea) lineages reveals gene order rearrangements in Cladocera
Full text linkThe class Branchiopoda, whose origin dates back to Cambrian, includes ~ 1200 species which mainly occupy freshwater habitats. The phylogeny and systematics of the class have been debated for long time, until recent phylogenomic analyses allowed to better clarify the relationships among major clades. Based on these data, the clade Anostraca (fairy and brine shrimps) is sister to all other branchiopods, and the Notostraca (tadpole shrimps) results as sister group to Diplostraca, which includes Laevicaudata + Spinicaudata (clam shrimps) and Cladoceromorpha (water fleas + Cyclestherida). In the present analysis, thanks to an increased taxon sampling, a complex picture emerges. Most of the analyzed mitogenomes show the Pancrustacea gene order while in several other taxa they are found rearranged. These rearrangements, though, occur unevenly among taxa, most of them being found in Cladocera, and their taxonomic distribution does not agree with the phylogeny. Our data also seems to suggest the possibility of potentially homoplastic, alternative gene order within Daphniidae
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