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La biologia riproduttiva del pesce spada xiphias gladius e del tonno rosso atlantico thunnus thynnus nel mar mediterraneo: basi per una gestione sostenibile della pesca
No full textIndagare la biologia riproduttiva e l'evoluzione contribuisce a definire un modello concettuale in grado di spiegare i processi che hanno permesso il successo di qualsiasi specie. L'emergere di caratteristiche anatomiche, di sviluppo e fisiologiche innovative che comportano un vantaggio selettivo è infatti strettamente legato al successo della strategia riproduttiva perché questo favorisce la sopravvivenza della specie. Inoltre, al giorno d'oggi, la comprensione delle strategie riproduttive è una chiave per un uso sostenibile delle risorse biologiche e per rispettare il principio di equità intergenerazionale, che consiste nel preservare le risorse naturali e l'ambiente a beneficio delle generazioni future.
Gli obiettivi generali della presente tesi di dottorato erano 1) indagare la biologia riproduttiva del pesce spada Xiphias gladius e del tonno rosso atlantico Thunnus thynnus nel Mar Mediterraneo nel contesto della gestione della pesca e 2) far luce sull'evoluzione di alcune caratteristiche anatomiche, comportamentali e fisiologiche peculiari delle due specie. Gli obiettivi dettagliati sono forniti per ogni capitolo come segue
1) Assegnazione della maturità basata su criteri macroscopici validati dall'istologia: affrontare il declino dello stock di pesce spada del Mediterraneo (Xiphias gladius)
- Obiettivi: i) migliorare la conoscenza della riproduzione del pesce spada nel Mediterraneo centrale e occidentale in termini di descrizione istologica degli stadi ovarici, tempi di riproduzione e dimensioni alla prima maturità (L50) ii) evidenziare l'importanza dell'indice gonadico (GI) come utile indicatore macroscopico attraverso la sua calibrazione con l'approccio istologico e la definizione di una soglia GI per discriminare le femmine sessualmente immature da quelle mature
2) Un approccio di assemblaggio de novo del trascrittoma chiarisce la dinamica della maturazione ovarica nel pesce spada (Xiphias gladius)
- Obiettivi: i) elucidare i processi molecolari che guidano la maturazione ovarica ii) identificare i principali geni del pathway molecolare della steroidogenesi e disegnare una via ad-hoc per la sintesi e l'endocitosi della vitellogenina integrata con i risultati di espressione genica iii) caratterizzare un candidato recettore della vitellogenina iv) rendere i risultati liberamente disponibili attraverso un portale online dedicato
3) Quando il calore fa la differenza: il trascrittoma del tessuto termogenico del pesce spada Xiphias gladius
- Obiettivi: i) fornire un toolbox molecolare per comprendere l'evoluzione dell'endotermia regionale nel pesce spada ii) espandere i risultati specie-specifici verso una più ampia esplorazione dell'evoluzione dell'endotermia nei vertebrati iii) contribuire alla conoscenza del tessuto termogenico a livello istologico
4) Assemblaggio de novo del trascrittoma, annotazione funzionale e caratterizzazione dello stadio larvale del tonno rosso atlantico (Thunnus thynnus)
- Obiettivi: i) fornire alla comunità scientifica che attualmente lavora sull'allevamento larvale un trascrittoma pronto all'uso e annotato rappresentativo dello stadio larvale ii) identificare i pathways molecolari alla base degli alti tassi di crescita larvale attraverso un approccio comparativo con altre specie di pesci iii) individuare le famiglie di proteine in espansione iv) esplorare le funzioni biologiche associate ai trascritti che hanno un bias di utilizzo dei codoni più elevato
5) Un confronto del potenziale riproduttivo in femmine giovani e vecchie: un caso di studio sul tonno rosso atlantico nel Mar Mediterraneo
- Obiettivi: i) chiarire il potenziale riproduttivo di vecchie e giovani femmine nel Mar Mediterraneo ii) caratterizzare l'espressione di mir-202 in giovani e vecchie femmine e tra periodi riproduttivi e non riproduttivi iii) identificare la localizzazione ovarica di mir-202 in ovari vitellogeniciInvestigating the reproductive biology and the evolution contributes to define a conceptual model able to explain the processes that allowed any species to succeed. The emergence of innovative anatomical, developmental and physiological features which entail a selective advantage is indeed tightly linked to the success of the reproductive strategy because this favours the species to survive. Furthermore, nowadays, understanding the reproductive strategies is a key for a sustainable use of the biological resources and to respect the principle of intergenerational equity, which consists in the preservation of natural resources and the environment for the benefit of future generations.
The overall objectives of the present doctoral dissertation were 1) to investigate the reproductive biology of the swordfish Xiphias gladius and the Atlantic bluefin tuna Thunnus thynnus in the Mediterranean Sea in the context of the fishery management and 2) to shed light onto the evolution of some peculiar anatomical, behavioral and physiological features of the two species. The detailed objectives are provided for each chapter as follows
1) Maturity assignment based on histology-validated macroscopic criteria: tackling the stock decline of the Mediterranean swordfish (Xiphias gladius)
• Aims: i) improving the knowledge of the swordfish reproduction in the central and western Mediterranean in terms of histological description of the ovarian stages, reproductive timing and size at first maturity (L50) ii) highlight the importance of the gonadic index (GI) as useful macroscopic indicator through its calibration with the histological approach and the definition of a GI threshold to discriminate sexually immature from mature females
2) A de novo transcriptome assembly approach elucidates the dynamics of ovarian maturation in the swordfish (Xiphias gladius)
• Aims: i) elucidating the molecular processes driving the ovarian maturation ii) identifying the main genes of the molecular pathway of steroidogenesis and draw an ad-hoc pathway for the vitellogenin synthesis and uptake integrated with gene expression results iii) characterizing a candidate vitellogenin receptor iv) making the results freely available through a dedicated online portal
3) Some like it hot: the heater tissue transcriptome of the swordfish Xiphias gladius
• Aims: i) providing a molecular toolbox to understand the evolution of the regional endothermy in the swordfish ii) expanding the species-specific findings towards the broader exploration of the evolution of endothermy in vertebrates iii) contributing to the knowledge on the heater tissue at a histological level
4) De novo transcriptome assembly, functional annotation and characterization of the Atlantic bluefin tuna (Thunnus thynnus) larval stage
• Aims: i) providing the scientific community currently working on the larval rearing with a ready-to-use and annotated transcriptome representative of the larval stage ii) identifying the molecular pathways underlying the high larval growth rates through a comparative approach with other fish species iii) detecting the expanding protein families iv) exploring the biological functions associated with transcripts having higher codon usage bias
5) A comparison of reproductive potential in young and old females: a case study on the Atlantic bluefin tuna in the Mediterranean Sea
• Aims: i) Elucidating the reproductive potential of old and young females in the Mediterranean Sea ii) characterizing the expression of mir-202 in young and old females and between reproductive and non-reproductive periods iii) identifying the mir-202 ovarian localization in vitellogenic ovarie
Opsins and gonadal circadian rhythm in the swordfish (Xiphias gladius) ovary: Their potential roles in puberty and reproductive seasonality
No full textCircadian rhythm is well known to play a pivotal role in reproduction but the presence of a gonadal circadian rhythm is opening a lot of questions about a local regulation of reproduction. In the present study, we first set to identify the key genes driving circadian rhythmicity from the gonadal transcriptome of the swordfish, a commercially relevant species undergoing overfishing, and we then investigated whether their transcriptional activity was influenced by the maturation stage. Finally, we explored whether seasonality had the ability to modulate the expression of these genes. Interestingly, we identified a wide number of circadian rhythm related genes in the transcriptome of the swordfish gonad including, among the others, clock, bmal1, cry2 and per2, which have been found to be differentially expressed between sexually immature and mature individuals sampled during the breeding season. This differential modulation was also found for melatonin biosynthesis genes (mel1b, asmt and tph1) as well as opsin genes (opsin4, tmt opsin, parapinopsin, VA opsin, rho and sws), known to be the primary receptors of light stimuli. These differences were not observed between mature and immature individuals when considering the non-breeding season suggesting that, despite the molecular machinery of mature gonads is able to respond to signals driving ovarian maturation, these signals are not present hence highlighting the potential role of seasonality in modulating the gonadal circadian rhythm. These results confirm the presence of a gonadal circadian rhythm in the swordfish and open new interesting questions about its role in driving puberty onset
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
A Window of Vulnerability: Chronic Environmental Stress Does Not Impair Reproduction in the Swordfish Xiphias gladius
Get PDFXiphias gladius is an important fishing resource. The Mediterranean stock is affected by overfishing and is declining. In this light, the aim of this study was to evaluate the cross-talk among metabolism, stress response, immune system and reproduction in immature and mature females, coupling histological and transcriptomic approaches. The transcriptome of livers from 3 immature and 3 mature females was analyzed using the Artificial Intelligence RNA-Seq. For the histological analysis, ovary and liver samples were collected from 50 specimens caught during the reproductive season in the Mediterranean Sea. A total of 750 genes were differentially expressed between the livers. The gene ontologtabey analysis showed 91 upregulated and 161 downregulated biological process GO terms. Instead, the KEGG enrichment analysis revealed 15 enriched pathways. Furthermore, the binding occurring between estrogen receptors and aryl hydrocarbon receptor nuclear translocator, upregulated in mature females, could be liable for the inhibition of detoxification pathway. Indeed, at the histological level, mature females showed a higher density and number of melanomacrophage centers, biomarkers of stress. The present findings reveal the cross-talk among response to environmental stressors, metabolism and reproduction, highlighting that mature females invest a lot of energy in reproduction instead of immune response and detoxification
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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