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VARIABILITÀ GENETICA E MORFOLOGICA NEL FRAGOLINO, PAGELLUS ERYTHRINUS
No full textABSTRACT
In the last decades, recent molecular approaches have lead to fundamental changes
in our understanding of marine population ecology. The classical notion that marine
environments tend to be demographically ‘open’, with high connectivity among
populations of infinite size and generally characterized by low genetic differentiation
(Hauser and Carvalho, 2008) is quite abandoned. In fact, recent genetic studies have
challenged such traditional view, by demonstrating genetic structuring in marine fish
species, even on a limited spatial scale (Knutsen et al., 2003; Jørgensen et al., 2005;
Knutsen et al., 2007). Moreover, it became clear that the degree of dispersion and the
extent of gene flow among marine populations are strongly influenced by
oceanographic discontinuities (transition areas that could determine
phylogeographic discontinuities) suggesting that the picture is much more complex
than previously assumed (Schunter et al., 2011).
In this context, we investigated the distribution of genetic and morphological
variability of Pagellus erythrinus (common pandora), one of the main target species in
Mediterranean commercial fisheries and whose knowledge on biological features is
still limited. The aim of this thesis was to investigate the degree of genetic structure
of common pandora, necessary for a correct management of this resource and, to
increase knowledge of the genetic variability distribution patterns in the Sparidae
family and, more generally, in Mediterranean demersal species. The morphological
analysis aims to investigate the degree of morphological differentiationon a
geographical basis, and its possible concordance/correlation with genetic variability.
Specimens were collected from 16 localities along the Italian (13 sites) and the
Tunisian coasts (2 sites), in the central Mediterranean Sea, and from one location in
the Atlantic Ocean, along the southern coast of Portugal.
Genetic analyses were carried out using three different molecular markers: two
mitochondrial DNA markers, control region (CR, sequence analysis) and cytochrome
b (Cyt b RFLP analysis) and a nuclear one, microsatellites (10 loci).
We identified three different mitochondrial lineageseach including individuals from
almost every sampling sites, without a geographic pattern. Nevertheless, different,
and statistically significant, frequency distribution was found for two of the these
lineages between the Mediterranean Sea and the Atlantic Ocean. The presence of
these long-diverged lineages, that now can be found in sympatry, is attributable to a
period of isolation followed by secondary contact. These events, likely due to climatic
fluctuations of the Pleistocene, left decipherable genetic footprints on
phylogeographic and demographic facets of common pandora history.
Microsatellites showed that present-day dynamics produces a weak but significant
genetic structure (Fst= 0.006, p < 0.05) among the examined localities. One Atlantic
and four Mediterranean subpopulations were identified, which might be explained
by the major oceanographic discontinuities and local currents described in the
investigated area. A certain degree of differentiation was observed for some localities
within the Mediterranean Sea (North Elba and along the Tunisian coasts) for which
phylogeographic breaks have not been reported so far. Further studies will be
necessary to better understand dispersal components in relation both to local
oceanographic conditions and adults mobility .
Data obtained with the two types of molecular markers allow us to assert that the
species in the past has been affected by processes of isolation, and, consequently,
genetic divergence of populations followed bysecondary contact, Under present day
conditions, populations are characterized by high connectivity and dispersal is
limited only in some restricted areas.
Morphological analysis was carried out by a geometric morphometrics approach,
through the detection of 20 landmarks. The analysis revealed morphological
variations in size and shape components, both between sexes and sites. The
variability in size could be due to different local environmental features and to the
hermaphroditism of the species. Differences in shape could be related to a slight
sexual dimorphism. Statistical tests revealed absence of correlation between
morphological and genetic patterns indicating that phenotypic plasticity and
adaptive divergence/convergence are potential mechanisms underlying
morphological differences detected among P. erythrinus
Genetic structure in lagoon samples of Atherina boyeri: effects of habitat discontinuity and low dispersal ability
No full textSynuclein expression in the african clawed frog Xenopus laevis
Get PDFThe synuclein (syn) family comprises three proteins (α-, β- and γ- syns) encoded by different genes (snca, sncb and sncg). In mammals, α- and β- syn are primarily expressed in the brain where they are localized in pre-synaptic terminals while γ-syn is mainly expressed in the peripheral nervous system. In humans, synucleins are involved in neurodegenerative diseases such as Parkinson's disease and in tumors. However, the normal cellular functions of the three syns have not yet been fully clarified.
Members of the syn family were sequenced in representative species of all vertebrates and the comparative analysis of amino acid sequences suggests that syns are evolutionarily conserved, but information about their expression in vertebrate lineages is still scarce.
Our research focused on the evolution of syns with the aim of analyzing their molecular and cellular expression in the CNS of representative vertebrates such as the carp Cyprinus carpio for teleost fish 1,2 and the green lizard Anolis carolinensis for reptiles 3.
Current model of our comparative analysis for amphibians is the african clawed frog Xenopus laevis. The only information available on syn expression in this species relate to embryonic stages but data on syn expression in the adult are still lacking. At larval stages, amphibian snca is expressed in the brain, branchial arches and somites, and sncb signals were detected in the entire brain and spinal cord whereas sncg was only expressed in the peripheral nervous system including trigeminal nerve and dorsal root ganglion 4.
Preliminary data are here reported on syn expression in adult specimen of X. laevis, obtained by RT-qPCR, Western blot and IHC. The results demonstrated that syns are expressed both in neuronal and non neuronal tissues suggesting differences in the expression pattern between developmental and adult stages.The synuclein (syn) family comprises three proteins (α-, β- and γ- syns) encoded by different genes (snca, sncb and sncg). In mammals, α- and β- syn are primarily expressed in the brain where they are localized in pre-synaptic terminals while γ-syn is mainly expressed in the peripheral nervous system. In humans, synucleins are involved in neurodegenerative diseases such as Parkinson's disease and in tumors. However, the normal cellular functions of the three syns have not yet been fully clarified.
Members of the syn family were sequenced in representative species of all vertebrates and the comparative analysis of amino acid sequences suggests that syns are evolutionarily conserved, but information about their expression in vertebrate lineages is still scarce.
Our research focused on the evolution of syns with the aim of analyzing their molecular and cellular expression in the CNS of representative vertebrates such as the carp Cyprinus carpio for teleost fish 1,2 and the green lizard Anolis carolinensis for reptiles 3.
Current model of our comparative analysis for amphibians is the african clawed frog Xenopus laevis. The only information available on syn expression in this species relate to embryonic stages but data on syn expression in the adult are still lacking. At larval stages, amphibian snca is expressed in the brain, branchial arches and somites, and sncb signals were detected in the entire brain and spinal cord whereas sncg was only expressed in the peripheral nervous system including trigeminal nerve and dorsal root ganglion 4.
Preliminary data are here reported on syn expression in adult specimen of X. laevis, obtained by RT-qPCR, Western blot and IHC. The results demonstrated that syns are expressed both in neuronal and non neuronal tissues suggesting differences in the expression pattern between developmental and adult stages
Immunoreactivity and expression of synucleins in the South African clawed frog Xenopus laevis peripheral nervous system
Get PDFHuman synucleins (syns) genes coding for α-, β- and γ- isoforms are highly expressed in mammalian nervous system, in particular α-syn is implicated in several neurodegenerative diseases collectively named synucleinopathies, including Parkinson's disease, frequently associated with motor impairment. The precise functions of syns remain elusive, but there are evidence indicating their involvement in the regulation of vesicular trafficking, exocytosis and synaptic function.
Because of the high degree of conservation of syns among vertebrates, non-mammalian animal models may provide additional information on the evolution and the physiological role of these proteins [1,2]. Preliminary data are here reported on α- and β- syns expression and their morphological localization in different organs of adult specimens of the South African clawed frog Xenopus laevis, obtained by RT-qPCR, Western blot (WB) and immunohistochemistry (IHC). In WB and IHC experiments, two different commercial antibodies against mammalian α-, β- syns were used. Alpha- and β-syn immunoreactivities were differently distributed in the various tissues analyzed. Interestingly α -syn immunoreactivity was detected in both peripheral and autonomous nervous system respectively innervating skeletal muscles, cardiovascular system and gastrointestinal tract. Alpha-syn immunoreactive (IR) nerve fibers were found along skeletal muscle fibers, showing large varicosities typical of neuromuscular junctions. Moreover, both submucosal and myenteric plexuses of the gastrointestinal tract showed IR fibers. These preliminary observations suggest a conserved role for α-syn in synaptic vesicle trafficking in peripheral nerves and suggest that Xenopus laevis may be a promising model for the study of synucleinopathies.Human synucleins (syns) genes coding for α-, β- and γ- isoforms are highly expressed in mammalian nervous system, in particular α-syn is implicated in several neurodegenerative diseases collectively named synucleinopathies, including Parkinson's disease, frequently associated with motor impairment. The precise functions of syns remain elusive, but there are evidence indicating their involvement in the regulation of vesicular trafficking, exocytosis and synaptic function.
Because of the high degree of conservation of syns among vertebrates, non-mammalian animal models may provide additional information on the evolution and the physiological role of these proteins [1,2]. Preliminary data are here reported on α- and β- syns expression and their morphological localization in different organs of adult specimens of the South African clawed frog Xenopus laevis, obtained by RT-qPCR, Western blot (WB) and immunohistochemistry (IHC). In WB and IHC experiments, two different commercial antibodies against mammalian α-, β- syns were used. Alpha- and β-syn immunoreactivities were differently distributed in the various tissues analyzed. Interestingly α -syn immunoreactivity was detected in both peripheral and autonomous nervous system respectively innervating skeletal muscles, cardiovascular system and gastrointestinal tract. Alpha-syn immunoreactive (IR) nerve fibers were found along skeletal muscle fibers, showing large varicosities typical of neuromuscular junctions. Moreover, both submucosal and myenteric plexuses of the gastrointestinal tract showed IR fibers. These preliminary observations suggest a conserved role for α-syn in synaptic vesicle trafficking in peripheral nerves and suggest that Xenopus laevis may be a promising model for the study of synucleinopathies
Nitric oxide and the neuroendocrine control of the osmotic stress response in teleosts
Get PDFThe involvement of nitric oxide (NO) in the modulation of teleost osmoresponsive circuits is suggested by the facts that NO synthase enzymes are expressed in the neurosecretory systems and may be regulated by osmotic stimuli. The present paper is an overview on the research suggesting a role for NO in the central modulation of hormone release in the hypothalamo-neurohypophysial and the caudal neurosecretory systems of teleosts during the osmotic stress response. Active NOS enzymes are constitutively expressed by the magnocellular and parvocellular hypophysiotropic neurons and the caudal neurosecretory neurons of teleosts. Moreover, their expression may be regulated in response to the osmotic challenge. Available data suggests that the regulatory role of NO appeared early during vertebrate phylogeny and the neuroendocrine modulation by NO is conservative. Nonetheless, NO seems to have opposite effects in fish compared to mammals. Indeed, NO exerts excitatory effects on the electrical activity of the caudal neurosecretory neurons, influencing the amount of peptides released from the urophysis, while it inhibits hormone release from the magnocellular neurons in mammals
Phylogeography of the common pandora Pagellus erythrinus in the central Mediterranean sea. Sympatric mitochondrial lineages and genetic homogeneity
No full textThe distribution of the genetic diversity and the population structure of Pagellus erythrinus were analysed using mitochondrial control region sequences and cytochrome b restriction profiles in a total of 128 and 508 individuals, respectively, that were collected from 15 sampling sites in the central Mediterranean Sea and from one site in the Atlantic Ocean. No population genetic structure was detected within the central Mediterranean, and thus, the commonly recognised transition zones in the area do not seem to affect population connectivity. The comparison between the Mediterranean samples and the single Atlantic sample suggests weak differentiation between the two basins. Three mitochondrial lineages were identified, each including individuals from almost every sampling site. The haplotype and nucleotide diversity values, mismatch distribution and demographic parameters indicate that the sympatry of these lineages can be ascribed to a period of isolation followed by genetic divergence, population expansion and secondary contact, all of which are likely to be associated with climatic oscillations that occurred during the middle and late Pleistocene
Genetic structure in lagoons: the effects of habitat discontinuity and low dispersal ability on populations of Atherina boyeri
No full textAtherina boyeri is a common inhabitant of the Mediterranean brackish and coastal waters. Several recent studies proposed the recognition of three distinct forms/species (one lagoon/freshwater and two marine) within an A. boyeri complex. In this study, we used 10 newly available microsatellite loci to better define the genetic structure of the lagoon form. A total of 428 fishes from 11 lagoons along the Italian and Albanian coasts and three Italian lakes were analyzed. A pronounced genetic spatial structure was confirmed for all considered geographic scales (near, medium and broad). A restricted gene flow was detected, suggesting reduced population connectivity. The comparison of present data and previous studies, based on mtDNA and RAPD markers, allowed a preliminary identification of the roles of recent factors (gene flow, habitat discontinuity and water currents) and past events (e.g., Pleistocene glaciations) in shaping the pattern of genetic differentiation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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