scholarly journals Effects of urea on the olfactory reception in zebrafish (Danio rerio)

2016 ◽  
Vol 89 (1) ◽  
Author(s):  
Lorenzo Gallus ◽  
Emiliano Marchesotti ◽  
Sonia Scarfì ◽  
Andrea Amaroli ◽  
Valeria Franceschini ◽  
...  
Keyword(s):  
Olfactory Epithelium ◽  
Danio Rerio ◽  
Direct Action ◽  
Olfactory Receptors ◽  
Olfactory Sensitivity ◽  
Urea Treatment ◽  
Olfactory Reception ◽  
G Protein Alpha Subunit ◽  
Protein Alpha Subunit

The effects of uremia on human olfactory functions have been clinically evaluated in various studies, even if to date it is not completely clarified which uremic toxins mediate these processes. Surprisingly, the role of the main molecule involved in uremia, urea indeed, has not been adequately investigated as other possible molecules may also be involved in uremic anosmia. The effects of urea on the olfaction have been evaluated in some clinical studies, but this is the first attempt to determine a direct action of urea on the olfactory epithelium of a vertebrate. <em>Danio rerio</em> adults were exposed to urea in different experiments to assess the effects on olfactory sensitivity and signal transduction. The analysis of the swimming speed has been used to evaluate the response to hypoxanthine 3-N-oxide (H3NO), a molecule that is known to elicit an olfactory-mediated alarm reaction in <em>D. rerio</em>. The presence and distribution of the G protein alpha subunit coupled to the olfactory receptors (Gα<sub>olf</sub>) has been immunohistochemically investigated in the olfactory epithelium of control and urea-exposed <em>D. rerio</em>. Our findings showed that urea alters the response to H3NO of <em>D. rerio</em> with a quite rapid and reversible effect that appears to be independent from a mere interference of urea on the receptor-ligand binding. The Gα<sub>olf</sub> protein resulted increases after urea treatment, suggesting an effect of urea on its expression or degradation.

Role of GnRH Isoforms in Paracrine/Autocrine Control of Zebrafish (Danio rerio) Spermatogenesis

Endocrinology ◽  
2020 ◽  
Vol 161 (2) ◽  
Author(s):  
Hamideh P Fallah ◽  
Maira S Rodrigues ◽  
Sheryll Corchuelo ◽  
Rafael H Nóbrega ◽  
Hamid R Habibi
Keyword(s):  
Danio Rerio ◽  
Direct Action ◽  
Strong Support ◽  
Relative Activity ◽  
Induced Response ◽  
Testicular Development ◽  
Adult Zebrafish ◽  
Autocrine Control ◽  
And Function

Abstract It is well established that hypothalamic GnRH (gonadotropin-releasing hormone) is one of the key peptides involved in the neuroendocrine control of testicular development and spermatogenesis. However, the role of GnRH as a paracrine regulator of testicular function has not been fully investigated. The present study demonstrates the presence of GnRH and its receptors in the zebrafish (Danio rerio) testis, and provides information on direct action of native GnRH isoforms (GnRH2 and GnRH3) on different stages of spermatogenesis in this model. Both GnRH2 and GnRH3 stimulated basal spermatogenesis by increasing numbers of type Aund spermatogonia, spermatozoa, and testosterone release, and in this study GnRH2 exerted higher relative activity than GnRH3. Next, we evaluated the effects of GnRH isoforms on human chorionic gonadotropin (hCG)- and follicle-stimulating hormone (Fsh)-induced spermatogenesis. The 2 GnRH isoforms were found to have different effects on Fsh- and hCG-induced response depending on the stage of spermatogenesis and concentration of the peptides. The results provide strong support for the hypothesis that locally produced GnRH2 and GnRH3 are important components of the complex multifactorial system that regulates testicular germinal cell development and function in adult zebrafish.

Kropotkin

2016 ◽  
Author(s):  
Ruth Kinna
Keyword(s):  
Political Theory ◽  
Human Nature ◽  
Political Change ◽  
Direct Action ◽  
The State ◽  
Social Analysis ◽  
Mutual Aid ◽  
Special Character ◽  
Revolutionary Politics

This book is designed to remove Peter Kropotkin from the framework of classical anarchism. By focusing attention on his theory of mutual aid, it argues that the classical framing distorts Kropotkin's political theory by associating it with a narrowly positivistic conception of science, a naively optimistic idea of human nature and a millenarian idea of revolution. Kropotkin's abiding concern with Russian revolutionary politics is the lens for this analysis. The argument is that his engagement with nihilism shaped his conception of science and that his expeditions in Siberia underpinned an approach to social analysis that was rooted in geography. Looking at Kropotkin's relationship with Elisée Reclus and Erico Malatesta and examining his critical appreciation of P-J. Proudhon, Michael Bakunin and Max Stirner, the study shows how he understood anarchist traditions and reveals the special character of his anarchist communism. His idea of the state as a colonising process and his contention that exploitation and oppression operate in global contexts is a key feature of this. Kropotkin's views about the role of theory in revolutionary practice show how he developed this critique of the state and capitalism to advance an idea of political change that combined the building of non-state alternatives through direct action and wilful disobedience. Against critics who argue that Kropotkin betrayed these principles in 1914, the book suggests that this controversial decision was consistent with his anarchism and that it reflected his judgment about the prospects of anarchistic revolution in Russia.

Ecology, Dharma and Direct Action: A Brief Survey of Contemporary Eco-Buddhist Activism in Korea

2015 ◽  
Vol 31 (2) ◽  
pp. 293-311
Author(s):  
Young-Hae Yoon ◽  
Sherwin Jones
Keyword(s):  
Social Engagement ◽  
Direct Action ◽  
Social Activism ◽  
Turn Of The Millennium ◽  
Hunger Strike ◽  
Korean Society ◽  
High Profile ◽  
Reclamation Project ◽  
Self Immolation

Over the last few decades there has emerged a small, yet influential eco-Buddhism movement in South Korea which, since the turn of the millennium, has seen several S?n (J. Zen) Buddhist clerics engage in high-profile protests and activism campaigns opposing massive development projects which threatened widespread ecological destruction. This article will survey the issues and events surrounding three such protests; the 2003 samboilbae, or ‘threesteps- one-bow’, march led by Venerable Suky?ng against the Saemangeum Reclamation Project, Venerable Jiyul’s Anti-Mt. Ch?ns?ng tunnel hunger-strike campaign between 2002 and 2006, and lastly Venerable Munsu’s self-immolation protesting the Four Rivers Project in 2010. This article will additionally analyze the attempts by these clerics to deploy innovative and distinctively Buddhist forms of protest, the effects of these protests, and how these protests have altered public perceptions of the role of Buddhist clergy in Korean society. This study will additionally highlight issues relevant to the broader discourse regarding the intersection of Buddhism and social activism, such as the appropriation of traditional Buddhist practices as protest tactics and the potential for conflict between social engagement and the pursuit of Buddhist soteriological goals.

scholarly journals Learning by Doing: The Use of Distance, Corners and Length in Rewarded Geometric Tasks by Zebrafish (Danio rerio)

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2001
Author(s):  
Greta Baratti ◽  
Angelo Rizzo ◽  
Maria Elena Miletto Petrazzini ◽  
Valeria Anna Sovrano
Keyword(s):  
Danio Rerio ◽  
Three Dimensional ◽  
Reference Memory ◽  
Spatial Abilities ◽  
Learning By Doing ◽  
Surface Distance ◽  
Extended Surfaces ◽  
Unequal Length ◽  
Over Time

Zebrafish spontaneously use distance and directional relationships among three-dimensional extended surfaces to reorient within a rectangular arena. However, they fail to take advantage of either an array of freestanding corners or an array of unequal-length surfaces to search for a no-longer-present goal under a spontaneous cued memory procedure, being unable to use the information supplied by corners and length without some kind of rewarded training. The present study aimed to tease apart the geometric components characterizing a rectangular enclosure under a procedure recruiting the reference memory, thus training zebrafish in fragmented layouts that provided differences in surface distance, corners, and length. Results showed that fish, besides the distance, easily learned to use both corners and length if subjected to a rewarded exit task over time, suggesting that they can represent all the geometrically informative parts of a rectangular arena when consistently exposed to them. Altogether, these findings highlight crucially important issues apropos the employment of different behavioral protocols (spontaneous choice versus training over time) to assess spatial abilities of zebrafish, further paving the way to deepen the role of visual and nonvisual encodings of isolated geometric components in relation to macrostructural boundaries.

Sign in / Sign up

Export Citation Format

Share Document