Mitochondrial phylogeny and taxonomic revision of Italian and Slovenian fluvio-lacustrine barbels, Barbus sp. (Cypriniformes, Cyprinidae).

BACKGROUND: Barbels are ray finned cyprinid fishes of the Old-World with partially unresolved, intricate taxonomy. Within the Barbus sensu lato paraphyletic assemblage, Barbus sensu stricto is a monophyletic tetraploid lineage of Europe, northern Africa and Middle East, including two monophyletic sibling genera: Barbus and Luciobarbus. Italy, Slovenia and northern Croatia are natively inhabited by several entities of the genus Barbus, whose relationships and taxonomic ranks are still unclear. Aim of the present work is to focus on phylogeography of Italian and Slovenian barbels, with an appraisal of their current taxonomy. RESULTS: One hundred fifty specimens were collected in 78 sampling sites from 33 main watersheds, widely distributed along Italian and Slovenian ichthyogeographic districts. We amplified two mitochondrial markers, cytochrome b (cytb) and control region (D-loop), to infer a robust phylogeny for our sample and investigate on species delimitation. Our results strongly indicate all Italian and Adriatic Slovenian fluvio-lacustrine barbels to be comprised into at least three distinct species. We provide a proposal of taxonomic revision and a list of synonymies for two of them and a new description under the International Code of Zoological Nomenclature rules for the third one. CONCLUSIONS: If nuclear data will confirm our findings, at least three specific entities should be acknowledged across our sampling area. Namely, the three species are (i) Barbus plebejus, in the Padano-Venetian district; (ii) Barbus tyberinus, in the Tuscany-Latium district; (iii) Barbus oscensis Rossi & Plazzi sp. nov., in the Tyrrhenian and southernmost-Adriatic parts of Apulia-Campania district. Finally, we briefly discuss the implications of such a taxonomic scenario on conservation policies.

Redox-Based Flagging of the Global Network of Oxidative Stress Greatly Promotes Longevity.

Despite more than 50 years of investigations into the free radical theory, the direct role of oxidative stress (OS) in aging and age-related diseases remains unproven. Little progress in identifying antioxidant drugs promoting longevity has been made, likely due to selectivity toward one or few radical species, variable efficacy in vivo, inherent pro-oxidant behavior of such drugs, or lack of synergism with metabolic redox homeostasis. Silencing the wide range of reactive free radicals has a great impact on OS-linked outcomes and age-related disorders. Here we show that an innovative, redox-active, multi-radical-scavenger catalytic drug delays the age-associated decline in physiological processes and markedly prolongs the mean lifespan of the adult freshwater annelids Aeolosoma viride by 170%. This unprecedented extension is associated with a decreased OS status. Consistently, treatment of annelids increases their natural resistance to oxygen-derived damage without affecting mitochondrial respiration or reproductive activity. Conversely, the superoxide dismutase (SOD)-mimetic EUK 134 that we selected as a positive control led to an increase in lifespan of ~50%, the same increase previously observed in nematodes. Our results show that reduction of the global network of OS has a profound impact on aging, prompting the development of a possible redox-based therapeutic intervention to counteract the progression of aging.

First report on the chromosomes of Aeolosoma viride and Aeolosoma hemprichi (Aeolosomatidae; Annelida).

Abstract Aeolosomatidae are cosmopolitan meiofaunal Annelida characterised by small size and almost exclusively asexual reproduction. This study is the first report on the chromosome morphology of two aeolosomatid species. Giemsa staining and propidium iodide labelling were performed. The somatic chromosome number of Aeolosoma viride was 2n=30 with many biarmed elements, whereas A. hemprichi showed 60 small chromosomes with a dot-like appearance. Asexual reproduction, with its clonal transmission of chromosomal repatternings, probably ensures the fixation of new karyotypes in species of Aeolosoma .

Morphological aspects of gonadal morphogenesis in Bufo bufo (Amphibia Anura): Bidder's organ differentiation.

We have described the architecture of Bidder's organ, defined its compartmented structure, and affirmed the presence of basal laminae. We did not find morphological differences between sexes in Bidder's organ. All specimens initially developed gonads with a peripheral fertile layer surrounding a thin primary cavity. The first oogenetic wave was observed early, showing all phases of meiosis, including leptotene, zygotene, and pachytene, which had been previously thought to be lacking. The peculiar presence of an asynchronous germ cell nest was discussed. Diplotene oocytes issued from the peripheral layer and migrated inside the primary cavity. They were surrounded by a single layer of follicular cells, which originated from the peripheral layer somatic cells and were delimited by a basal lamina. There were few medulla or central layer cells. At the end of metamorphosis, while the oocytes of the first oogenetic wave came into close contact with blood vessels, a second oogenetic wave took place just as the first, except for the presence of synchronous germ cell nests. The central layer was not visible and we did not observe the formation of an ovarian pocket. Stocks of stem germ cells remained in the peripheral layer during both the first and second oogenetic waves. The asymmetric model, in which there is a tendency toward a primary female differentiation, was confirmed. The female differentiation becomes stable in the Bidder's organ because of the absence of further interaction between germ and medullary somatic cells, which would have led toward a male differentiation.

Ultrastructural aspects of gonadal morphogenesis in Bufo bufo (Amphibia Anura) 1. Sex differentiation.

The morphogenesis of gonads in Bufo bufo tadpoles was studied, and ultrastructural differences between sexes were identified. All specimens analyzed initially developed gonads made up of a peripheral fertile layer (cortex) surrounding a small primary cavity. Subsequently a central layer of somatic cells (medulla) developed. Both layers were separated by two uninterrupted basal laminae between which a vestige of the primary cavity persisted. During female differentiation, the peripheral layer continued to be the fertile layer. In males, the central layer blended into the peripheral layer and the basal laminae disappeared. The somatic cells of the central layer came into direct contact with the germ cells; this did not occur in females. Testicular differentiation continued with the migration of germ cells towards the center of the gonad. The somatic elements surrounding the germ cells appeared to play an active role in their transfer to the center of the gonad. The peripheral layer shrank and became sterile. Two basal laminae then re-formed to separate the fertile central layer from the peripheral sterile one. Germ cells have always been thought to perform a passive role in sex differentiation in amphibians. Following the generally accepted "symmetric model", the mechanism of gonad development is symmetrical, with cortical somatic cells determining ovarian differentiation and medullary somatic cells determining testicular differentiation. In contrast, we found that sex differentiation follows an "asymmetric" pattern in which germ cells tend primarily toward a female differentiation and male differentiation depends on a secondary interaction between germ cells and medullary somatic cells.