1,720,999 research outputs found
Spermatogenesis advancement in pre-pubertal meagre Argyrosomus regius treated with recombinant gonadotropins
No full textΤhe effects of recombinant meagre follicle stimulating hormone (rFsh) and luteinizing hormone (rLh) were evaluated on testicular maturation in pre-pubertal meagre Argyrosomus regius, an upcoming aquaculture species in the Mediterranean region. Fish (body mass 1092.9 ± 178.8 g) received seven weekly injections of meagre rFsh, together with an rLh injection at week 6. One group was further treated with weekly rFsh or rLh until week 11 and was sacrificed at week 12 (rFsh/rLh group, TREATED 12). The second group received further weekly injections of rFsh until week 12 and was then left untreated until week 21 (single rLh group, TREATED 21). Control fish received injections of saline solution. At week 12, the testes of the rFsh/rLh-treated fish (TREATED 12) showed increased gonadosomatic index and seminiferous tubule diameter, reduction of spermatogonial density, increase of post-meiotic spermatocysts and accumulation of luminal spermatozoa. In the single rLh-treated group (TREATED 21), apoptosis increased towards pre-treatment levels, demonstrating that the withdrawal of the Fsh stimulus ceased the process of spermatogenesis. The results demonstrated the effectiveness of rFsh/rLh treatment in stimulating testicular growth, spermiogenesis and spermiation in pre-pubertal meagre
Increased melanomacrophage centres in the liver of reproductively dysfunctional female greater amberjack Seriola dumerili (Risso, 1810)
Full text linkThe greater amberjack Seriola dumerili is a new aquaculture fish that may display reproductive dysfunctions. During extensive follicular atresia, which is a common reproductive dysfunction in females during vitellogenesis, part of the reabsorbed yolk returns to the liver to be metabolized and recycled. Melanomacrophage centres (MMCs) are aggregates of macrophage-like cells that play a role in the destruction, detoxification and recycling of endogenous and exogenous materials, and have been associated with systemic stress. Wild and captive-reared greater amberjack were sampled in the Mediterranean Sea during two different phases of the reproductive cycle. The liver of reproductively dysfunctional captive-reared females sampled during the spawning season showed a high density of both MMCs and apoptotic cells. A weak liver anti-cytochrome P450 monooxygenase 1A immunoreactivity was observed, suggesting that the examined fish were not exposed to environmental pollutants. We propose that the observed increase in MMCs and apoptosis in captive-reared fish was related to the hepatic overload associated to the metabolism of yolk proteins reabsorbed during extensive follicular atresia. Since follicular atresia is a frequent physiological and pathological event in teleosts, we suggest that the reproductive state should be always assessed when MMCs are used as markers of exposure to stress or pollutants
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
Male germ cell proliferation and apoptosis in sexually immature meagre Argyrosomus regius (Asso, 1801) treated with recombinant follicle stimulating hormone
Full text linkThe meagre Argyrosomus regius (Asso, 1801) is a marine fish species that has an increasing aquaculture production in Europe. Lowering the age at maturity of hatchery-produced juveniles would support meagre aquaculture by reducing time between generations in selective breeding programs and reducing industrial costs for broodstock maintenance. The aim of this work was to assess the effects of a treatment with recombinant follicle stimulating hormone (rFsh), produced in ovarian cells of Chinese hamsters, on male germ cell proliferation and apoptosis in sexually immature meagre. The rFsh-treated fish had higher gonadosomatic index, larger seminiferous tubules, more abundant luminal spermatozoa, a lower density of anti-PCNA positive single A spermatogonia, a higher density of anti-PCNA positive spermatocysts and a lower incidence of germ cell apoptosis than control groups. The present study demonstrated the effectiveness of the produced rFsh in stimulating testis development and spermatogenesis in pre-pubertal meagre. Moreover, the rFsh treatment proved to be highly efficient in removing the apoptotic block of spermatogenesis observed in juvenile meagre, allowing spermatogonial survival and progress towards meiosis. The administration of rFsh did not stimulate spermatogonial self-renewal, a process whose control still needs to be elucidated
Variations on the Author
Full text link“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
Full text linkWe 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
GnRHa-induced spawning in cage-reared Atlantic bluefin tuna: an evaluation using stereological quantification of ovarian post-ovulatory follicles
No full textThe effect of a delivery system (implant) loaded with gonadotropin-releasing hormone agonist (GnRHa) on
the spawning performance in captive-reared Atlantic bluefin tuna (Thunnus thynnus) was assessed by means
of stereological quantification of ovarian post-ovulatory follicles (POF). Among untreated control fish no
follicles were observed at the oocyte maturation (OM) stage; in contrast, 10 of the 16 GnRHa-treated fish
showed follicles containing migratory-nucleus oocytes and/or hydrating oocytes. Post-ovulatory follicles
were observed only in three of the 14 untreated individuals examined, while all but one GnRHa-induced fish
showed POF in the ovary. Nevertheless, when POF were present in the ovary, the amount of ovulated oocytes
was not found to be significantly different among GnRHa-treated and untreated control fish, and wild
spawners. The relative batch fecundity (eggs g−1 of body mass) estimated from ovarian POF counts were
109.62±28.36 (control group), 68.92±13.05 (GnRHa-treated group) and 83.47±15.63 (wild group). It was concluded that treatment with GnRHa implant stimulated OM and spawning in captivity, thus enhancing the
reproductive potential of the broodstocks; however, there appears to be a limitation in the number of eggs maturing in each batch, and the spawn fecundity was not increased by the hormonal treatment
Dietary diisononylphthalate contamination induces hepatic stress: a multidisciplinary investigation in gilthead seabream (Sparus aurata) liver
No full textIn this study, adult gilthead seabream (Sparus aurata) were exposed for 21 days to Di-iso-nonylphthalte (DiNP at 15 and 1500 μg kg−1 bw day−1) via the diet. This plastic additive has been recently introduced to replace the di-(2-ethylhexyl)phthalate, the toxicity of which has been demonstrated conclusively both in vivo and in vitro trials. An analysis of a set of biomarkers involved in stress and immune response provides evidence of hepatic toxicity by DiNP in the present study. Both hsp70 and gr mRNA levels were upregulated significantly by DiNP, while plasma cortisol increased only in fish fed with the lowest DiNP dose. The oxidative stress markers g6pdh, glut red, gpx1 and CAT were upregulated by DiNP; gst mRNA was induced by the high dose and gck mRNA was downregulated significantly by the low dose. The mRNA levels of genes involved in the immune response, such as pla2, 5-lox, tnfa and cox2, were upregulated significantly only by the high dose of DiNP, while il1 mRNA increases in both doses. These molecular evidences were complemented with features obtained by Fourier Transform Infrared Imaging (FTIRI) analysis regarding the hepatic distribution of the main biological macromolecules. The FTIRI analysis showed an alteration of biochemical composition in DiNP samples. In particular, the low dose of DiNP induced an increase of saturated and unsaturated lipids and phosphorylated proteins, and a decrease of glycogen levels. The levels of caspase did not change significantly in the study, suggesting that DiNP does not activate apoptosis. Finally, the results also suggested the onset of hepatic oxidative stress and the activation of immune response, adding new knowledge to the already described hepatic DiNP toxicity
) and other members of the family Carangidae
Full text linkThe family Carangidae contains several species of aquaculture interest, including the amberjacks, yellowtails and trevallies. Among them, the greater amberjack (Seriola dumerili), the Japanese amberjack or yellowtail (Seriola quinqueradiata) and the yellowtail kingfish (Seriola lalandi) are considered the species with the highest potential for commercial aquaculture. Understanding the reproductive physiology–biology, spawning kinetics and production characteristics in captivity are of utmost importance for the domestication of any animal, and developing broodstock management methods and therapies to optimize egg production and overcome potential reproductive dysfunctions are essential. The present article reviews the available literature on the reproductive biology of the Carangidae species of interest for the aquaculture industry, both in the wild and under farming conditions. The reproductive traits of wild and farmed fish, whenever available, were compared in order to improve the understanding of the reproductive dysfunctions occurring in captivity. Finally, the hormonal maturation and spawning induction protocols examined so far to ameliorate the reproductive dysfunctions and obtain fertile gametes are summarized, and their effectiveness in the different rearing conditions is discussed
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