1,720,994 research outputs found
Activity of etv5a and etv5b genes in the hypothalamus of fasted zebrafish is influenced by serotonin
Get PDFSerotonin has been implicated in the inhibition of food intake in vertebrates. However, the mechanisms through which serotonin acts has yet to be elucidated. Recently, ETV5 (ets variant gene 5) has been asso- ciated with obesity and food intake control mechanisms in mammals. We have analyzed a putative phys- iological function of the two etv5 paralogous genes (etv5a and etv5b) in neuronal food intake control in adult zebrafish that have been exposed to different nutritional conditions. A feeding assay was estab- lished and fluoxetine, a selective serotonin re-uptake inhibitor (SSRI), was applied. Gene expression changes in the hypothalamus were determined using real-time PCR. Fasting induced an up-regulation of etv5a and etv5b in the hypothalamus, whereas increased serotonin levels in the fasted fish counter- acted the increase in expression. To investigate potential mechanisms the expression of further food intake control genes was determined. The results show that an increase of serotonin in fasting fish causes a reduction in the activity of genes stimulating food intake. This is in line with a previously demonstrated anorexigenic function of serotonin. Our results suggest that obesity-associated ETV5 has a food intake stimulating function and that this function is modulated through serotonin.Fil: Mechaly, Alejandro. University of Sydey. Sydney Medical School; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Richardson, Ebony. University of Sydey. Sydney Medical School; AustraliaFil: Rinkwitz, Silke. University of Sydney. Sydney Medical School; Australi
Overview and New Insights Into the Diversity, Evolution, Role, and Regulation of Kisspeptins and Their Receptors in Teleost Fish
Get PDFIn the last two decades, kisspeptin (Kiss) has been identified as an important player in the regulation of reproduction and other physiological functions in vertebrates, including several fish species. To date, two ligands (Kiss1, Kiss2) and three kisspeptin receptors (Kissr1, Kissr2, Kissr3) have been identified in teleosts, likely due to whole-genome duplication and loss of genes that occurred early in teleost evolution. Recent results in zebrafish and medaka mutants have challenged the notion that the kisspeptin system is essential for reproduction in fish, in marked contrast to the situation in mammals. In this context, this review focuses on the role of kisspeptins at three levels of the reproductive, brain-pituitary-gonadal (BPG) axis in fish. In addition, this review compiled information on factors controlling the Kiss/Kissr system, such as photoperiod, temperature, nutritional status, sex steroids, neuropeptides, and others. In this article, we summarize the available information on the molecular diversity and evolution, tissue expression and neuroanatomical distribution, functional significance, signaling pathways, and gene regulation of Kiss and Kissr in teleost fishes. Of particular note are recent advances in understanding flatfish kisspeptin systems, which require further study to reveal their structural and functional diversity.Fil: Wang, Bin. Chinese Academy Of Fishery Sciences; ChinaFil: Mechaly, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Somoza, Gustavo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin
A review of the biology and ecology of Artemia persimilis Piccinelli & Prosdocimi, 1968 (Crustacea: Anostraca), as basis for its management
Get PDFThe genus Artemia (brine shrimp) is a small cosmopolitan crustacean, which primarily inhabits hypersaline water bodies, such as inland salt lakes, ponds and coastal lagoons. In Argentina two bisexual populations are encountered: Artemia franciscana and A. persimilis. The second is believed to be endemic to Argentina, but recently there have been some reports of their presence in a few locations in southern Chile. Artemia have been extensively studied because it is the most useful living food resource for the larval states of fish and crustaceans, and because of their unique reproductive strategies. Many authors in Argentina have agreed to indicate that A. persimilis needs special attention, and should be evaluated as a natural resource for aquaculture. The present paper provides a brief review of ecological aspects of A. persimilis and an overview of their use in aquaculture.Fil: Mechaly, Alejandro. University of Sidney; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Angeletti, Sabrina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: De los Ríos Escalante, Patricio. Universidad Católica de Temuco; ChileFil: Cervellini, Patricia Marta. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Seafood in Argentina: marine fish species, seasonal presence and prices
No full textArgentina is among the 20 largest seafood producing countries in the world, with an annual fish capture of about 800,000 tons. However, national annual fish consumption is low, about 5 kg per cap- ita, and the domestic seafood market is little known. The objective of this study was to contribute to the characterization of seafood in the Argentine mar- ket. Monthly landings, presence at points of sale and prices of seafood were analyzed. The seafood data were gathered from official statistics of the Under- secretariat of Fisheries and Aquaculture, statistics from the Central Market of Buenos Aires and surveys conducted in fish shops in the city of Mar del Plata. Based on the monthly seasonal index (SI), price vari- ations throughout the year were studied. Likewise, relative fish prices were determined by using as unit the price of Argentine hake (Merluccius hubbsi), which is the most consumed fish in the country. This study identified the marine species most present in the domestic market and their prices. The presence of the different fish species at the points of sale could not be directly associated with their landing seasons. There was also no direct link between fish prices and quan- tities landed. No significant seasonal fluctuations in prices were found on seafood products (SI=90–110), with the exception of hake fillet (SI=80–113). Many finfishes had a price peak during Easter week. Over- all, price patterns suggest that seafood prices in Argentina are mainly determined by demand rather than supply. Further research on seafood traceability and fish consumption is needed to advance the under- standing of the seafood market in Argentina.Fil: Hirt Chabbert, Jorge Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Mechaly, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Tapia, Ciro. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin
Kisspeptin and GnRH interactions in the reproductive brain of teleosts
No full textIt is well known that gonadotropin-releasing hormone (Gnrh) has a key role in reproduction by regulating the synthesis and release of gonadotropins from the anterior pituitary gland of all vertebrates. About 25 years ago, another neuropeptide, kisspeptin (Kiss1) was discovered as a metastasis suppressor of melanoma cell lines and then found to be essential for mammalian reproduction as a stimulator of hypothalamic Gnrh and regulator of puberty onset. Soon after, a kisspeptin receptor (kissr) was found in the teleost brain. Nowadays, it is known that in most teleosts the kisspeptin system is composed of two ligands, kiss1 and kiss2, and two receptors, kiss2r and kiss3r. Even though both kisspeptin peptides, Kiss1 and Kiss2, have been demonstrated to stimulate gonadotropin synthesis and secretion in different fish species, their actions appear not to be mediated by Gnrh neurons as in mammalian models. In zebrafish and medaka, at least, hypophysiotropic Gnrh neurons do not express Kiss receptors. Furthermore, kisspeptinergic nerve terminals reach luteinizing hormone cells in some fish species, suggesting a direct pituitary action. Recent studies in zebrafish and medaka with targeted mutations of kiss and/or kissr genes reproduce relatively normally. In zebrafish, single gnrh mutants and additionally those having the triple gnrh3 plus 2 kiss mutations can reproduce reasonably well. In these fish, other neuropeptides known to affect gonadotropin secretion were up regulated, suggesting that they may be involved in compensatory responses to maintain reproductive processes. In this context, the present review explores and presents different possibilities of interactions between Kiss, Gnrh and other neuropeptides known to affect reproduction in teleost fish. Our intention is to stimulate a broad discussion on the relative roles of kisspeptin and Gnrh in the control of teleost reproduction.Fil: Somoza, Gustavo Manuel. Universidad Nacional de San Martin. Instituto Tecnológico de Chascomús - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Tecnológico de Chascomús; ArgentinaFil: Mechaly, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Trudeau, Vance L.. University of Ottawa; Canad
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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