scholarly journals The role of TASK-2 channels in CO2 sensing in zebrafish (Danio rerio)

2020 ◽  
Vol 319 (3) ◽  
pp. R329-R342
Author(s):  
N. Koudrina ◽  
S. F. Perry ◽  
K. M. Gilmour
Keyword(s):  
Danio Rerio ◽  
Ventilatory Response ◽  
Indirect Evidence ◽  
Adult Zebrafish ◽  
Larval Zebrafish ◽  
Neuroepithelial Cells ◽  
Cardiorespiratory Reflexes ◽  
Or Task ◽  
And Task

Peripheral chemosensitivity in fishes is thought to be mediated by serotonin-enriched neuroepithelial cells (NECs) that are localized to the gills of adults and the integument of larvae. In adult zebrafish ( Danio rerio), branchial NECs are presumed to mediate the cardiorespiratory reflexes associated with hypoxia or hypercapnia, whereas in larvae, there is indirect evidence linking cutaneous NECs to hypoxic hyperventilation and hypercapnic tachycardia. No study yet has examined the ventilatory response of larval zebrafish to hypercapnia, and regardless of developmental stage, the signaling pathways involved in CO2 sensing remain unclear. In the mouse, a background potassium channel (TASK-2) contributes to the sensitivity of chemoreceptor cells to CO2. Zebrafish possess two TASK-2 channel paralogs, TASK-2 and TASK-2b, encoded by kcnk5a and kcnk5b, respectively. The present study aimed to determine whether TASK-2 channels are expressed in NECs of larval zebrafish and whether they are involved in CO2 sensing. Using immunohistochemical approaches, TASK-2 protein was observed on the surface of NECs in larvae. Exposure of larvae to hypercapnia caused cardiac and breathing frequencies to increase, and these responses were blunted in fish experiencing TASK-2 and/or TASK-2b knockdown. The results of these experiments suggest that TASK-2 channels are involved in CO2 sensing by NECs and contribute to the initiation of reflex cardiorespiratory responses during exposure of larvae to hypercapnia.

Loss of M2 muscarinic receptor function inhibits development of hypoxic bradycardia and alters cardiac β-adrenergic sensitivity in larval zebrafish (Danio rerio)

2009 ◽  
Vol 297 (2) ◽  
pp. R412-R420 ◽  
Author(s):  
Shelby L. Steele ◽  
Kwok Hong Andy Lo ◽  
Vincent Wai Tsun Li ◽  
Shuk Han Cheng ◽  
Marc Ekker ◽  
...  
Keyword(s):  
Heart Rate ◽  
Muscarinic Receptor ◽  
Danio Rerio ◽  
Antisense Oligonucleotides ◽  
Adrenergic Receptor ◽  
Larval Zebrafish ◽  
M2 Muscarinic Receptor ◽  
Β Adrenergic Receptors ◽  
Relative Mrna Expression

Fish exposed to hypoxia develop decreased heart rate, or bradycardia, the physiological significance of which remains unknown. The general muscarinic receptor antagonist atropine abolishes the development of this hypoxic bradycardia, suggesting the involvement of muscarinic receptors. In this study, we tested the hypothesis that the hypoxic bradycardia is mediated specifically by stimulation of the M2 muscarinic receptor, the most abundant subtype in the vertebrate heart. Zebrafish ( Danio rerio) were reared at two levels of hypoxia (30 and 40 Torr Po2) from the point of fertilization. In hypoxic fish, the heart rate was significantly lower than in normoxic controls from 2 to 10 days postfertilization (dpf). At the more severe level of hypoxia (30 Torr Po2), there were significant increases in the relative mRNA expression of M 2 and the cardiac type β-adrenergic receptors ( β1AR, β2aAR, and β2bAR) at 4 dpf. The hypoxic bradycardia was abolished (at 40 Torr Po2) or significantly attenuated (at 30 Torr Po2) in larvae experiencing M2 receptor knockdown (using morpholino antisense oligonucleotides). Sham-injected larvae exhibited typical hypoxic bradycardia in both hypoxic regimens. The expression of β1AR, β2aAR, β2bAR, and M 2 mRNA was altered at various stages between 1 and 4 dpf in larvae experiencing M2 receptor knockdown. Interestingly, M2 receptor knockdown revealed a cardioinhibitory role for the β2-adrenergic receptor. This is the first study to demonstrate a specific role of the M2 muscarinic receptor in the initiation of hypoxic bradycardia in fish.

The role of acid-sensing ion channels in epithelial Na+ uptake in adult zebrafish (Danio rerio)

2015 ◽  
Vol 218 (8) ◽  
pp. 1244-1251 ◽  
Author(s):  
A. K. Dymowska ◽  
D. Boyle ◽  
A. G. Schultz ◽  
G. G. Goss
Keyword(s):  
Ion Channels ◽  
Danio Rerio ◽  
Adult Zebrafish ◽  
Acid Sensing Ion Channels ◽  
Na Uptake

Regeneration of the gill filaments and replacement of serotonergic neuroepithelial cells in adult zebrafish (Danio rerio)

2020 ◽  
Vol 274 ◽  
pp. 103366
Author(s):  
Anna S. Mierzwa ◽  
Frederic Nguyen ◽  
Mark Xue ◽  
Michael G. Jonz
Keyword(s):  
Danio Rerio ◽  
Adult Zebrafish ◽  
Neuroepithelial Cells ◽  
Gill Filaments

scholarly journals Followers’ HEXACO personality traits and preference for charismatic, relationship-oriented, and task-oriented leadership

2019 ◽  
Author(s):  
Kimberley Breevaart ◽  
Reinout E. de Vries
Keyword(s):  
Personality Traits ◽  
Charismatic Leadership ◽  
Openness To Experience ◽  
Nomological Network ◽  
Charismatic Leader ◽  
Need Fulfillment ◽  
Task Oriented ◽  
Or Task ◽  
And Task

AbstractThe aim of the current study was to examine the HEXACO personality traits in relation to followers’ preference for charismatic, relationship-oriented, and task-oriented leadership. Based on the similarity perspective, we expected followers high on Honesty-Humility, Extraversion, and Openness to Experience to prefer a charismatic leader, and those followers high on conscientiousness and low on Openness to Experience to prefer a task-oriented leader. In addition, from a need fulfillment perspective, we expected followers high on Emotionality to prefer a task- and a relationship-oriented leader. We examined these expectations using paper vignette methodology in a sample of 272 undergraduates. The results showed that most participants preferred a relationship-oriented leader over a charismatic or task-oriented leader. In addition, we found support for all our hypotheses, with the exception of the relations between Honesty-Humility and preference for charismatic leadership, and Conscientiousness and preference for task-oriented leadership. Our findings contribute to the nomological network of the role of follower characteristics in the leader-follower relationship. Implications and suggestions for research on charismatic leadership are provided.

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.

scholarly journals Critical Language Pedagogy and Task-Based Language Teaching: Reciprocal Relationship and Mutual Benefit

2021 ◽  
Vol 11 (6) ◽  
pp. 254
Author(s):  
Graham V. Crookes ◽  
Nicole Ziegler
Keyword(s):  
Second Language ◽  
Second Language Acquisition ◽  
Language Teaching ◽  
Reciprocal Relationship ◽  
Short Term ◽  
Language Pedagogy ◽  
Teaching Content ◽  
Or Task ◽  
And Task

Curriculum development and empirical research in the field of second language acquisition could benefit the field of critical language pedagogy (CLP) and its practitioners. This article reviews central concepts in the organization of curriculum in CLP and compares them with another major curricular initiative in second language teaching, namely task-based or task-supported approaches, with particular emphasis on task-based language teaching. Content itself (as in activities or materials) and the role of metacognitive instruction are considered. A real-world example of a task-based or task-supported short-term program is reviewed as exemplifying some areas of contact or benefit.

scholarly journals Hif-1α paralogs play a role in the hypoxic ventilatory response of larval and adult zebrafish (Danio rerio)

2018 ◽  
Vol 222 (2) ◽  
pp. jeb195198 ◽  
Author(s):  
Milica Mandic ◽  
Velislava Tzaneva ◽  
Vincent Careau ◽  
Steve F. Perry
Keyword(s):  
Danio Rerio ◽  
Ventilatory Response ◽  
Hypoxic Ventilatory Response ◽  
Adult Zebrafish
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