1,721,485 research outputs found
B chromosomes in Palinurus gilchristi) (Crustacea, Decapoda).
No full textB chromosomes in {Palinurus gilchristi} (Crustacea, Decapoda)
Coluccia E, Cannas R, Salvadori S, Cau A, Deiana AM
Dipartimento di Biologia Animale ed Ecologia, Università di Cagliari, Italy
We analyzed mitotic and meiotic chromosomes of {Palinurus gilchristi} Stebbing, 1900, a South African spiny lobster exploited by intensive fishery activity. So far the chromosome complement of this species is unknown. Mitotic and meiotic chromosomes from testis tissue were studied. Metaphase plates, obtained by air-drying techniques were Wright’s stained and C-banded.
Late prophases/metaphases I bivalents showed cross, ring and dumb-bell figures; some unpaired chromosomes, completely C-positive, were present. To study the chromosome number, mitotic and metaphase II chromosomes and metaphase I bivalents were counted. Numerical variability was observed (2n=120 ÷132, n=60 ÷ 72), that could be due to the presence of heterochromatic, asynaptic B chromosomes. Two types of Bs have been identified depending on their size: small and micro Bs; their total number varied from 3 to 7.
It is noteworthy that in the two other congeneric species, {P. elephas} and {P. mauritanicus} we studied, B chromosomes with similar morphology have been Among Decapoda, B chromosomes have been found in two Nephropidae species, {Nephrops norvegicus} and {Homarus americanus}
Studio del cariotipo di Gymnothorax tile (Osteichthyes, Anguilliformes).
No full textSTUDIO DEL CARIOTIPO DI GYMNOTHORAX TILE (OSTEICHTHYES, ANGUILLIFORMES).
SALVADORI S., COLUCCIA E., CANNAS R., MILIA A., DEIANA A.M.
Dipartimento di Biologia Animale ed Ecologia, Università di Cagliari, Viale Poetto 1, 09126 Cagliari. [email protected]
In questo lavoro presentiamo lo studio del cariotipo di Gymnothorax tile (Hamilton, 1822), un’anguilliforme appartenente alla famiglia Muraenidae che vive in acque salmastre del Pacifico occidentale e dell’Oceano Indiano; è possibile reperirla nei negozi di pesci per acquario. Questo è il primo studio sul complemento cromosomico di questa specie, in bibliografia sono presenti solo scarse informazioni sulla sua biologia. Sono stati studiati sei esemplari, tutti di sesso femminile da cui sono stati ottenuti i preparati cromosomici mediante colture di sangue.
E’ stato determinato il numero diploide 2n = 42 e per la costruzione del cariotipo è stato misurato l’indice centromerico di ogni coppia cromosomica, utilizzando il software Cromowin System (Amplimedical). I cromosomi sono stati classificati secondo Levan et al., (1964) e ordinati nel cariotipo in due gruppi: uno costituito da 17 coppie di cromosomi meta-, submeta- e subtelocentrici; l’altro da 4 coppie di cromosomi acrocentrici. All’interno dei due gruppi i cromosomi sono stati disposti in ordine di lunghezza decrescente.
L’applicazione del bandeggio C, che evidenzia la localizzazione dell’eterocromatina costitutiva, ha permesso l’identificazione di molte coppie di cromosomi omologhi, caratterizzate da evidenti e peculiari bande eterocromatiche. Tutti i cromosomi del complemento presentano bande eterocromatiche centromeriche, in alcune coppie sono inoltre presenti bande telomeriche e bande intercalari anche molto ampie.
Dal confronto con le altre specie studiate della famiglia Muraenidae si nota che il numero cromosomico riscontrato in G. tile, 2n = 42, è quello modale della famiglia, infatti è presente in 5 delle 7 specie studiate. Per quanto riguarda la struttura del cariotipo, G. tile e G. reevesii presentano un numero di bracci (NF = 76) notevolmente più alto rispetto alle altre specie. In base a studi morfologici e molecolari, la famiglia Muraenidae è ritenuta la più primitiva dell’ordine degli Anguilliformi e da un punto di vista citogenetico, presenta tra i più alti numeri cromosomici e contenuti di DNA/nucleo
Mitotic and meiotic chromosomes of the american lobster Homarus americanus (Nephropidae, Decapoda).
No full textMitotic and meiotic chromosomes of the American lobster Homarus americanus (Nephropidae, Decapoda)
Coluccia E., Cau A., Cannas R., Milia A., Salvadori S., Deiana A.M.
Dipartimento di Biologia Animale ed Ecologia, Università di Cagliari, Viale Poetto 1, 09126 Cagliari, Italy.
Homarus americanus H. Milne Edwards is an important target of North American commercial fishery. The very few karyological studies on this species have documented a remarkable intraspecific numerical variability of the chromosome complement; in order to explain this, the presence of supernumerary chromosomes has been hypothesised though not cytologically demonstrated (Roberts, 1969; Hughes, 1982). Supernumerary (B) chromosomes are additional chromosomes, highly polymorphic in number and morphology within populations and species, and their presence has already been shown in a species of the family Nephropidae (Deiana et al., 1996). In this study we characterise the mitotic and meiotic chromosomes of H. americanus by different banding techniques, and provide evidence of the presence of chromosomes, in this species, with some of the features of the B chromosomes. Chromosome preparations have been obtained from testicular tissue using an air-drying technique. C-banding, fluorochrome-banding and restriction enzyme-induced banding (RE) have allowed a clear identification of meiotic figures and the study of the distribution and structure of heterochromatic regions. These regions are localised on most centromeres and react specifically to the digestion with different REs and to the GC – and AT- specific fluorochrome stainings. Our results point out the GC richness of H. americanus heterochromatin, as shown by the bright fluorescence of most of heterochromatic regions after staining with the GC- specific fluorochrome, chromomycin A3. On the other hand, only few centromeric regions are fluorescent after staining with the AT-specific fluorochromes, DAPI, and Quinacrine. Furthermore the adopted techniques have revealed presence of small B chromosomes, completely heterochromatic, variable in number, and often asynaptic in first meiotic metaphase. The presence of these chromosomes can, at least partially, account for the numerical variability already observed in the karyotype of this species
La Roccaccia di Selvena (Castell’Azzara – GR): relazione della campagna 2000 e revisione dei dati delle precedenti
No full textcura dell'articolo con testi di E. Baldi, T. Cavallo, F. Cavanna, C. Citter, L. Giustarini, S. Giustarini, S. Menci, H. Salvadori, S. Savelli, C. Valdambrini, S. Zuccherin
Mining the Galactic halo for very metal-poor stars
No full textWe study the age and metallicity distribution function (MDF) of metal-poor stars in the Milky Way halo as a function of galactocentric radius by combining N-body simulations and semi-analytical methods. We find that the oldest stars populate the innermost region, while extremely metal-poor stars are more concentrated within r < 60kpc. The MDF of [Fe/H] <= -2 stars varies only very weakly within the central 50kpc, while the relative contribution of [Fe/H] <= -2 stars strongly increases with r, varying from 16 per cent within 7 < r < 20kpc up to >=40 per cent for r > 20kpc. This is due to the faster descent of the spatial distribution (as seen from Earth) of the more enriched population. This implies that the outer halo < 40kpc is the best region to search for very metal-poor stars. Beyond ~60kpc the density of [Fe/H] <= -2 stars is maximum within dwarf galaxies. All these features are imprinted by a combination of (i) the virialization epoch of the star-forming haloes, and (ii) the metal enrichment history of the Milky Way environment
Heart transplantation in pediatric age
No full textJ Cardiovasc Med (Hagerstown). 2007 Jan;8(1):67-71.
Heart transplantation in pediatric age.
Milanesi O, Cerutti A, Biffanti R, Salvadori S, Gambino A, Stellin G.
Source
Department of Pediatrics, University of Padova School of Medicine, Padova, Italy. [email protected]
Abstract
Heart transplantation, formerly the final option for terminally ill children, has now become the treatment of choice for a number of serious acquired or congenital cardiac conditions, which cannot be treated conservatively. Nevertheless, several problems remain unsolved. First of all the shortage of donors, mainly in the first months and years of life, which has become more and more significant with time, regardless of the country, religious belief or culture of the people. Secondly, the long-term impact of immunosuppression in a developing organism, and its possible inter-relation with the primary disorder, which leads to intractable heart failure. Whether a heart transplant is a cure or an ongoing disease for both the child and the family is another matter of concern. These and other topics are covered in this article.
PMID:
17255820
[PubMed - indexed for MEDLINE
Interaction of FCE 22176, a stable prostacyclin analogue, with different prostaglandins in guinea-pig trachea and atria.
No full textFCE 22176, a stable derivative of a PGI2 analogue, was studied in guinea-pig isolated atria and trachea. The compound was without inotropic or chronotropic effects in spontaneously beating atria and did not alter tracheal tone. By contrast, FCE 22176 competitively antagonized the inotropic effect of PGI2 on atria, and inhibited the PGI2-induced contraction of tracheal chains. Furthermore, in tracheal chains, FCE 22176 was able to antagonize the contractile effect of PGF2 alpha, and to enhance PGE2-induced relaxation. These data support our previous findings that FCE 22176 is a PGI2 antagonist, and provide evidence also for a more complex effect on prostaglandin receptors
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
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