scholarly journals Relative Mass of Brain- and Intestinal Tissue in Juvenile Brown Trout: No Long-Term Effects of Compensatory Growth; with Additional Notes on Emerging Sex-Differences

Fishes ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 38
Author(s):  
Joacim Näslund
Keyword(s):  
Sex Differences ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Compensatory Growth ◽  
Fork Length ◽  
Relative Mass ◽  
Long Term Effects ◽  
Treatment Groups ◽  
Trade Offs

This study investigated whether compensatory growth causes long-term effects in relative brain- or intestine size in a wild, predominantly anadromous, population of brown trout (Salmo trutta). The subject fish belonged to two treatment groups; one group had undergone starvation and subsequent growth compensation, while the other were unrestricted controls. The main hypothesis that compensatory growth would negatively affect brain and intestinal size, as a consequence of growth trade-offs during the compensatory phase, could not be supported as no significant differences were detected between the treatment groups. Further exploratory analyses suggested that males and females started to diverge in both brain and intestine size at around 130 mm fork length, with females developing relatively smaller brains and larger intestines. The size at which the differences appear is a typical size for smoltification (saltwater preadaptation), and females tend to smoltify to a higher proportion than males. Smoltification is known to cause a more elongated morphology and relatively smaller heads in salmonids, and the marine lifestyle is associated with rapid growth, which could require relatively larger intestines. Hence, these emerging sex differences could be a consequence of sex-biased smoltification rates. An investigation of wild smolts of both sexes indicated no differences in brain or intestine mass between male and female smolts.

scholarly journals The long-term bio-behavioural effects of juvenile sildenafil treatment in Sprague-Dawley versus Flinders Sensitive Line rats

2021 ◽  
pp. 1-20
Author(s):  
Juandré Lambertus Bernardus Saayman ◽  
Stephanus Frederik Steyn ◽  
Christiaan Beyers Brink
Keyword(s):  
Sprague Dawley ◽  
Long Term Effects ◽  
Bdnf Level ◽  
Treatment Groups ◽  
Sd Rats ◽  
Behavioural Effects ◽  
Sensitive Line ◽  
Level Analysis ◽  
Flinders Sensitive Line

Abstract Objective: To investigate the long-term effects of juvenile sub-chronic sildenafil (SIL) treatment on the depressive-like behaviour and hippocampal brain-derived neurotrophic factor (BDNF) levels of adult Sprague-Dawley (SD) versus Flinders Sensitive Line (FSL) rats. Methods: SD and FSL rats were divided into pre-pubertal and pubertal groups, whereafter 14-day saline or SIL treatment was initiated. Pre-pubertal and pubertal rats were treated from postnatal day 21 (PND21) and PND35, respectively. The open field and forced swim tests (FST) were performed on PND60, followed by hippocampal BDNF level analysis one day later. Results: FSL rats displayed greater immobility in the FST compared to SD rats (p < 0.0001), which was reduced by SIL (p < 0.0001), regardless of treatment period. Hippocampal BDNF levels were unaltered by SIL in all treatment groups (p > 0.05). Conclusion: Juvenile sub-chronic SIL treatment reduces the risk of depressive-like behaviour manifesting during young adulthood in genetically susceptible rats.

Social Justice through Inclusion

2017 ◽  
Author(s):  
Francesca R. Jensenius
Keyword(s):  
Political Elite ◽  
Long Term Effects ◽  
Quota System ◽  
Trade Offs ◽  
Combining Evidence ◽  
Elite Level ◽  
Scheduled Castes ◽  
Archival Work ◽  
Depth Interviews

India has one of the most extensive quota systems in the world: the reserved seats for the Scheduled Castes (SCs, the former “untouchables”) in the country’s legislative assemblies. Combining evidence from quantitative datasets from the period 1969–2012, archival work, and in-depth interviews with politicians, civil servants, and voters across India, this book explores the long-term effects these quotas have had for the political elite and for the general population. It finds that the quotas have played an important role in reducing caste-based discrimination, particularly at the elite level. Contrary to what one might expect, this is not because the quota system has led to more group representation—SC politicians working specifically for SC interests—but because it has created and empowered a new SC elite who have gradually become integrated into mainstream politics. The findings and discussions have broader implications beyond the case of India. Policies such as quotas are often implemented with the explicit goal of changing society and are supported with arguments that assume various positive, long-term consequences. The nuanced discussions in this book shed light on how the quotas for SCs have shaped the incentives for politicians, parties, and voters, noting the trade-offs inherent in how such policies of group inclusion are designed.

EFFECTS OF UNTREATED AND CHEMICALLY DISPERSED OIL ON TROPICAL MARINE COMMUNITIES: A LONG-TERM FIELD EXPERIMENT

1989 ◽  
Vol 1989 (1) ◽  
pp. 447-454 ◽  
Author(s):  
Thomas G. Ballou ◽  
Stephen C. Hess ◽  
Richard E. Dodge ◽  
Anthony H. Knap ◽  
Thomas D. Sleeter
Keyword(s):  
Field Experiment ◽  
Sea Urchins ◽  
Exposure Level ◽  
Long Term Effects ◽  
Worst Case ◽  
Dispersed Oil ◽  
Trade Offs ◽  
Chemically Dispersed Oil ◽  
Term Field

ABSTRACT A multidisciplinary long-term field experiment was conducted to evaluate the use of chemical dispersants to reduce the adverse environmental effects of oil spills in nearshore, tropical waters. Three study sites, whose intertidal and subtidal components consisted of mangroves, seagrass beds, and coral reefs, were studied in detail before, during, and after exposure to untreated crude oil or chemically dispersed oil. This study simulated an unusually high (“worst case”) exposure level of dispersed oil and a moderate exposure level of untreated oil. The third site served as an untreated reference site. Assessments were made of the distribution and extent of contamination by hydrocarbons over time, and the short- and long-term effects on survival, abundance, and growth of the dominant flora and fauna of each habitat. The whole, untreated oil had severe, long-term effects on survival of mangroves and associated fauna, and relatively minor effects on seagrasses, corals, and associated organisms. Chemically dispersed oil caused declines in the abundance of corals, sea urchins, and other reef organisms, reduced coral growth rate in one species, and had minor or no effects on seagrasses and mangroves. Conclusions were drawn from these results on decision making for actual spills based on trade-offs between dispersing or not dispersing the oil. This report deals only with the major results of the study. A large number of parameters were monitored, but in the interest of brevity only the most important aspects of the study are reported here. A detailed description of the methods used and a complete presentation and discussion of results is given in Ballou et al.2

scholarly journals Trade-offs between the short- and long-term effects of residue quality on soil C and N dynamics

2010 ◽  
Vol 338 (1-2) ◽  
pp. 159-169 ◽  
Author(s):  
Roberta Gentile ◽  
Bernard Vanlauwe ◽  
Pauline Chivenge ◽  
Johan Six
Keyword(s):  
Residue Quality ◽  
Long Term Effects ◽  
N Dynamics ◽  
Soil C ◽  
Trade Offs ◽  
Short And Long Term ◽  
Soil C And N ◽  
C And N ◽  
C And N Dynamics

An experimental evaluation of competitive and thermal effects on brown trout (Salmo trutta) and Bonneville cutthroat trout (Oncorhynchus clarkii utah) performance along an altitudinal gradient

2005 ◽  
Vol 62 (12) ◽  
pp. 2784-2795 ◽  
Author(s):  
Peter McHugh ◽  
Phaedra Budy
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Abiotic Factors ◽  
Cutthroat Trout ◽  
Reverse Direction ◽  
Mountain Stream ◽  
Oncorhynchus Clarkii ◽  
Treatment Groups ◽  
Brown Trout Salmo Trutta ◽  
Bonneville Cutthroat Trout

Temperature-mediated competition (i.e., dominance shifts between species depending on temperature) may explain the segregation of salmonid species along altitudinal stream gradients. We evaluated this hypothesis for exotic brown trout (Salmo trutta) and native Bonneville cutthroat trout (Oncorhynchus clarkii utah) by rearing them in experimental sympatry and allopatry using enclosures constructed at six sites spaced along a 45-km segment of a mountain stream. For both species, we compared condition and growth between allopatric and sympatric treatment groups. We found that brown trout negatively affected cutthroat trout performance, whereas cutthroat trout failed to impart an effect in the reverse direction, regardless of temperature. Thus, we documented asymmetric competition between these species but found little evidence indicating that its outcome was influenced by temperature. Brown trout – cutthroat trout segregation is therefore unlikely to be due to temperature-mediated competition. Instead, brown trout may have displaced cutthroat trout from downstream areas through competition or other mechanisms, while abiotic factors preclude their (brown trout) invasion of upper elevations. Given the magnitude of effect observed in our study, we recommend that brown trout receive greater consideration in cutthroat trout conservation.

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