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Gli asinelli bianchi dell’Asinara: una razza di animali albini? IV Congresso Nazionale Biodiversità, Alghero 8-11 Settembre 1998
No full textLa razza degli asinelli bianchi dell’Asinara, come indicato nel Registro Anagrafico delle popolazioni equine riconducibili a gruppi etnici locali [D. M. 27-7-1990] e nell’Atlante etnografico delle popolazioni equine ed asinine per la salvaguardia delle risorse genetiche, per le sue condizioni di isolamento geografico e per la sua esiguità numerica necessita di un adeguato piano di salvaguardia e valorizzazione. Per appurare un’eventuale forma di albinismo, quale responsabile del colore bianco del mantello, a completamento di particolareggiate visite cliniche individuali, sono stati analizzati prelievi bioptici cutanei di sei asinelli bianchi e di uno grigio dell’Asinara mediante metodiche istologiche specifiche per il pigmento melanico (impregnazione argentica) ed immunoistochimiche (antisieri immunoreagenti con i melanociti normali - proteina 100 - e con quelli attivati - HMB45). Nello strato basale dell’epidermide del soggetto grigio si sono riscontrati abbondante pigmento melanico e pochi melanociti. Negli asinelli bianchi, alle diverse età, non si è riscontrato pigmento melanico. Nel soggetto bianco più giovane si è osservato un numero più elevato di melanociti rispetto agli animali, più anziani nei quali è risultato simile a quello grigio. Quest’ultima osservazione può essere spiegata come risposta proliferativa iperplastica limitata alla prima fase di vita, che viene indotta con meccanismo di feed back dalla incapacità dei melanociti di sintetizzare pigmento. Tale risposta tende ad esaurirsi con l’avanzare dell’età dei soggetti. I rilievi clinici unitamente all’assenza completa di melanina cutanea permettono di inquadrare il fenomeno in un’espressione fenotipica di albinismo di tipo oculo-cutaneo.The white donkey of Asinara (Sardinia- Italy) belongs to the local ethnic groups. It is reported in the Registry Book of the equine populations [Ministerial decree 27-7-1990] and in the Ethnographic Atlas of Italian horse and ass populations for the conservation of the genetic resources. Because of the animals geographical isolation and of their small number it is necessary to apply an appropriate strategy of conservation and valorisation. A clinical examination gave a positive picture to the hypothesis that albinism is the origin of the white colour of the animals coat. Aiming to verify this, from in 6 white and 1 grey asses biopsy samples of skin were taken to be analysed. They were stained with specific histological methods for melanin: a)Fontana-Masson’s silver staining; b)immuno-histo-chemical staining with policlonal antibodies against S-100 protein and c)with HMB45 to find activated melanocytes, if any. In the epidermis basal layer of the grey ass a wide presence of melanin and few melanocytes were observed. The melanin was completely absent in the white asses skin; moreover only in the youngest white donkey (8 months of age) a more large number of melanocytes was found compared with the others, this seems to be a hyperplasia, due to the inability of the cells to synthesise melanin. Increasing the animals age, this feed-back mechanism decreases and disappears as observed in the older white asses. The lack of skin melanin associated with the clinical pictures leads to the conclusion it is an oculo-cutaneous albinism
Tyrosinase activity and ocular characteristics in Asinara white donkeys
No full textThe population of white asses of the Asinara isle (Italy) is characterised by white hair and coat, pink colour of glabrous areas of the body and skin, partial pigmentation of the iris. Our previous studies allowed to classify this phenotype as the expression of an oculocutaneous albinism. Aiming to go deeper into the knowledge of this kind of albinism in the population, the ophthalmic examination was performed and the tyrosinase activity of the hair bulb was studied in 5 animals of different age. The fundus of eye was observed an photographed with the portable hand held fundus camera (Kowa) and it showed a complete lack of pigment both in the retinal pigment epithelium and in the choroid. The lack of pigment makes transparent these two layers thus the vascular structure of the choroid becomes visible, both in the non tapetal fundus and in correspondence of the tapetal fundus, which is transparent too. Specific biochemical tests with L-tyrosine and L-DOPA, were carried aiming to evaluate the tyrosinase activity of the hair bulb, a marked pigmentation of the bulb was obtained when using DOPA, but the melanin was not produced at all when using the tyrosine. This means that the synthesis of melanin has a metabolic block of the conversion from tyrosine to DOPA which is the not active the next reaction which leads to the production of melanin
Relazioni genetiche tra le popolazioni asinine della Sardegna. Analisi con marcatori molecolari
No full textLe popolazioni dell’asino sardo e dell’Asinara sono molto ridotte di numero e considerate in via di estinzione; perciò si
ritiene importante, se non essenziale per la corretta applicazione dei programmi di recupero di queste razze, caratterizzarle
geneticamente per studiarne le relazioni esistenti. La ricerca è stata condotta su 61 animali: 20 asini sardi, 21 asini dell’Asinara
e 20 asini comuni. Da ciascun soggetto è stato prelevato un campione di sangue per l’estrazione del DNA. Sono
stati analizzati 11 microsatelliti polimorfici, i cui primer sono contenuti nel kit “StockMarks® for Horses, Equine Paternity
PCR typing Kit” commercializzato da PE Applied Biosystem per analisi di parentela nei cavalli. I microsatelliti sono stati
amplificati mediante PCR, gli amplificati sono stati analizzati mediante elettroforesi su sequenziatore ABI PRISM 377,
Perkin-Elmer. Sono state calcolate le distanze genetiche tra le popolazioni applicando le formule della Distanza Minima di
Nei (Dm) e della Distanza di Reynold (DReynold) che sono state rappresentate graficamente mediante due alberi UPGMA. L’analisi
dei risultati ha evidenziato che le popolazioni dell’asino sardo e di quello comune sono le più vicine geneticamente,
mentre si distanziano notevolmente da quelle degli asini bianchi, che sono peraltro molto distanti tra loro. Si è osservato
che il campione degli asini bianchi, non era omogeneo, ma formato da due gruppi nettamente distinti: da un lato la popolazione
stanziale dell’Asinara e dall’altro il gruppo di animali allevato dall’Istituto di Incremento Ippico della Sardegna nell’azienda
di Foresta Burgos.The populations of Sardinian donkeys and Asinara donkeys are numerically reduced and considered in danger of extinction.
It is therefore considered important, if not essential, for the correct application of preservation programs for these animals,
to characterize them genetically in order to study relationships among the breeds. The research was conducted on 61
animals: 20 Sardinian donkeys, 21 Asinara donkeys and 20 mixed breed donkeys. A blood sample was taken from each
subject for the DNA extraction. We analyzed 11 polymorphic microsatellites, whose primers are contained in the kit “Stock-
Marks® for Horses, Equine Paternity PCR typing Kit” supplied by PE Applied Biosystem. The microsatellites were amplified by
PCR, then the PCR products were analyzed by electrophoresis on a Perkin-Elmer ABI PRISM 377 sequencer. The genetic distances
between the populations were calculated by applying the formulas of the Minimum Distance of Nei (Dm) and of the
Distance of Reynolds (DReynolds) and represented graphically by means of two UPGMA trees. From a preliminary analysis of
the data it was observed that the group of the white donkeys was not homogeneous, but was formed of two clearly distinct
groups: on one hand the population living on Asinara and on the other the group of animals raised on the Burgos Forest farm
of the Institute for the Improvement of Horse Breeding in Sardinia. An analysis of the results showed that the Sardinian
donkeys and the mixed breed donkeys are closest genetically, while both are remarkably distant from the 2 white donkey populations.
Moreover, the two groups of white donkeys were genetically distant
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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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