115,538 research outputs found
Field and laboratory approaches to assess "estrogen disruption" in the brown trout "Salmo trutta"
No full textIn recent years, the annual catches of brown trout and other native fish species
have been declining in Switzerland about 60%. One hypothesis was that the
reduced catch is linked to estrogen-active chemicals entering the aquatic
environment via waste water effluents. These so–called environmental estrogens
have the potential to mimic the actions of endogenous hormones and impair the
reproductive fitness of fish. The present thesis aimed to assess the reproductive
health of brown trout in Swiss rivers and to link putative reproductive disturbances
with the exposure to waterborne estrogens. In this context, we tracked field as well
as laboratory based approaches.
In order to assess whether the reproductive health of feral brown trout is disturbed,
we applied two different sampling strategies - namely passive and active
monitoring approaches. In the first approach, we sampled feral fish at three sites
along four rivers with a well documented catch decline. These rivers are affected
by inputs of wastewater effluents. The sampling was conducted during two years;
we measured plasma vitellogenin (Vtg) concentrations and surveyed gonadal
histology. In general, our data indicate that effects of environmental estrogens in
Swiss rivers are low. In only 5% of the analyzed males, we found plasma Vtg
concentrations higher than 1 μg/mL. Also the incidence of ovarian atresia was low
and we found no male intersex fish. In contrast to males, females caught along
two rivers had spermatogenic activity in ovarian tissue. However, this intersex
condition does not appear to be linked to environmental estrogens. In our second
field trial, we developed a mini–caging method to suit the hydrological conditions
in small rivers and to improve upon the often poor survival of salmonids in caging
trials. After three weeks of exposure, we measured plasma yolk protein and linked
the Vtg concentrations with the bioaccumulation of estrogens in bile of caged
fish. Because of the estrogenicity of river water is highly variable and it is difficult to
obtain an average measure of the estrogenicity we additionally tested the use of
passive sampling by means of polar organic chemical integrative samplers
(POCIS). The POCISs were positioned upstream and downstream of wastewater
treatment works. Concurrently, water grab samples were taken at each site.
Concentrations of estrogens were determined using a yeast-based reporter gene
assay and chemical analysis. Results from grab sampling, passive sampling, and
bioaccumulation were correlated; however, plasma vitellogenin concentrations
were elevated at only 1 of 5 sites. The POCISs provided an integrated and
biologically meaningful measure of estrogenicity in that they accumulated
estrogens in a pattern similar to that of brown trout. The mini caging appears a
significant methodological advance; no fish were lost, moreover, all fish survived in
excellent health. On the basis of our field data, we conclude that impaired
reproductive health does not appear to be a major factor contributing to the
marked decline of brown trout catches in the four investigated rivers. In addition to
the potential risk of environmental estrogens, increasing water temperatures as a
result of global warming has become a serious problem in many Swiss rivers and
streams. In particular low mountain range rivers frequently reach temperatures
that are suboptimal for many salmonid species. In our field surveys, we used the
analysis of Vtg as an indicator of estrogenic exposure. Little, however, is known
regarding the potential interaction between ambient water temperature and the
Vtg production induced by waterborne environmental estrogens. In order to test
the influence of temperature on Vtg synthesis, we exposed juvenile brown trout to
ethinylestradiol (EE2) and hold them either at low or high temperatures (12°C and
19°C, respectively), but also at temperature cycles of 12°-19°C to simulate the field
situation. The EE2 exposure caused a 7 to 74-fold increase of hepatic Vtg mRNA
and the synthesis Vtg mRNA was clearly stimulated in fish hold at higher water
temperatures. On the protein level, Vtg showed a similar pattern; the higher the
temperature, the higher the concentration of Vtg in the plasma. The experiment
further revealed a temperature dependent increasing amount of hepatic
estrogen receptor alpha mRNA after exposure to waterborne EE2. The gene
expression of estrogen receptor beta-1 and the glucocorticoid receptor in the liver
of EE2 exposed fish, however, showed no treatment related alterations. In line with
observed constant bile cortisol concentrations, our data do not indicate any stress
related effects on hepatic Vtg production. The present experiment, however,
clearly demonstrated that ambient temperature significantly change the
estrogen-induced expression of Vtg and therefore may alter the interpretation of
environmental monitoring studies under field conditions.
Changing water temperature alters the permeability of the gills and result in a
disturbed mineral balance in fish. The branchial sodium pump (Na+/K+–ATPase)
enables teleosts to cope with such varying environmental conditions and
compensates for the temperature–related loss of ions by active ion uptake from
the ambient water. Estrogens have the potential to interfere with the endocrine
regulation of Na+/K+–ATPase and may affect the molecular expression of sodium
pump mRNA and related branchial steroid receptors (mineralocorticoid and
glucocorticoid receptor). In the light of a recently observed warming of Swiss rivers
as well as the occurrence of estrogen-active chemicals in river water, such
interactions may have detrimental effects on the general health of brown trout in
Switzerland. To test the influence of temperature on the regulation of Na+/K+–
ATPase we used the same juvenile brown trout as described above in the Vtg
study. Data obtained from quantitative PCR evidenced a significant down
regulation of Na+/K+-ATPase gene expression in gills from estrogen–treated brown
trout held at low and fluctuating temperatures. However, the expression of Na+/K+–
ATPase in estrogen-treated fish from the EE2–high temperature group were not
significant lower than the control groups – indicating a response to the elevated
water temperatures. No significant effects on the number of immunoreactive
chloride cells were found; though, estrogen treatment tend to reduce the protein
abundance of Na+/K+–ATPase in the gills. The synthesis of mineralocorticoid
receptor mRNA correlated significantly with the expression of Na+/K+–ATPase. In
contrast, bile cortisol levels and the glucocorticoid receptor gene expression were
not affected by estrogen treatment alone or in combination with elevated
temperatures. This suggests that the expression of Na+/K+–ATPase is probably
regulated via the mineralocorticoid receptor. In addition, the lack of cortisol
response as well as the absence of effects on higher levels of biological
organization (e.g. histology or condition factor) suggests that the temperature
regimes used in the present study were insufficient to cause stressful conditions in
brown trout
Detection of QTL with effects on osmoregulation capacities in the rainbow trout (Oncorhynchus mykiss)
No full textBackground
There is increasing evidence that the ability to adapt to seawater in teleost fish is modulated by genetic factors. Most studies have involved the comparison of species or strains and little is known about the genetic architecture of the trait. To address this question, we searched for
QTL affecting osmoregulation capacities after transfer to saline water in a nonmigratory captive-bred population of rainbow trout.
Results
A QTL design (5 full-sib families, about 200 F2 progeny each) was produced from a cross between F0 grand-parents previously selected during two generations for a high or a low cortisol response after a standardized confinement stress. When fish were about 18 months old (204 g body weight), individual progeny were submitted to two successive hyper-osmotic challenges (30g of salt/L) at a 14 d interval. Plasma chloride and sodium concentrations were
recorded 24h after each transfer. After the second challenge, fish were sacrificed and gill index (weight of total gill arches corrected for body weight) was recorded. The genome scan was performed using 200 microsatellites and 88 SNP markers. Unitrait and multitrait QTL analyses evidenced a total of 15 and 7 different QTL (P<0.10) for plasma ion concentrations and gill index respectively. Among the most significant QTL, three affected concentrations of both chloride and sodium during both challenges, two were specific to either chloride or
sodium concentrations, three QTL were specific to gill index, and three affected both gill index and ionic concentrations in plasma. Altogether, allelic effects were consistent for QTL affecting chloride and sodium concentrations but inconsistent for QTL affecting ionic
concentrations and gill morphology. There was no systematic lineage effect (grand-parental origin of QTL alleles) on the recorded traits.
Conclusions
For the first time, genomic loci associated with effects on major physiological components of osmotic adaptation to seawater in a nonmigratory fish were revealed. The results pave the way for further deciphering of the complex regulatory mechanisms underlying seawater adaptation
and genes involved in osmoregulatory physiology in rainbow trout and other euryhaline fishes
Estudo da salmonização do filé de jundiá (Rhamdia quelen), através da adição de corantes naturais à ração.
No full textTCC (graduação em Engenharia de Aquicultura) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, 2007O experimento realizado visa a salmonização do filé do jundiá (Rhamdia quelen), por meio da adição de diferentes tipos de corantes à ração, como uma alternativa de agregação de valor ao produto, baseado no que atualmente acontece em peixes salmonídeos. Para o estudo estão sendo utilizados 900 juvenis, com peso médio de 8,23 ± 0,19 g e comprimento total médio de 9,41 ± 0,84 cm, distribuídos ao acaso em 36 caixas de água de cimento amianto, com volume de 1000 litros (1 peixe/40 litros). Num período de 60 dias, 12 tratamentos serão utilizados com 3 repetições cada, utilizando ração com 32% de proteína bruta e 3200 kcal de energia bruta por quilograma de ração, fornecida diariamente na quantia de 5 % da biomassa viva. A essas rações foram adicionadas diferentes quantidades de corantes naturais, sendo elas: 30 60 e 90 mg de astaxantina por quilograma na ração; 30 60 e 90 mg de cantaxantina por quilograma na ração e 30 60 e 90 mg de urucum por quilograma na ração. A avaliação visual da coloração foi realizada após o primeiro e segundo mês e comparada ao Guia de Pigmentação para salmonídeos da Roche "Salmonfan", e comparando com o aparelho eletrônico colorímetro Minolta CR-300. Ao final do experimento, a quantificação química dos carotenóides totais pela extração com acetona e leitura em espectrofotômetro a 470 nm será realizada. Os resultados parciais mostram que ainda não é possível a afirmação de que esteja havendo alguma coloração aos filés, pois houve divergência entre os resultados obtidos pelos métodos de avaliação utilizados, e também pelos filés apresentarem coloração muito parecida. Por tanto será necessária a análise final através da quantificação dos carotenóides para poder se afirmar se as sutis diferenças de colorações são resultados do acúmulo dos corantes
Characterization of myocardial Na(+)-Ca2+ exchange in rainbow trout
No full textThis study compared Na(+)-Ca2+ exchange from the hearts of rainbow trout with that from canines. In several respects, trout cardiac Na(+)-Ca2+ exchange is functionally similar to that from dogs and other mammals. Trout cardiac Na(+)-Ca2+ exchange is stimulated approximately 200% after 30-min incubation with 10 micrograms/ml chymotrypsin at 21 degrees C, similar to mammals. On the other hand, both the temperature and pH dependencies are strikingly different between the trout and canine myocardial Na(+)-Ca2+ exchange. While canine heart Na(+)-Ca2+ exchange exhibits a Q10 of greater than 2 (similar to values observed in other mammals), that from trout is relatively insensitive to temperature with a Q10 of approximately 1.2. The absolute rates of Na(+)-Ca2+ exchange in trout heart are four- to sixfold higher than that in mammals when measured at 7 degrees C. Furthermore, the temperature insensitivity of trout myocardial Na(+)-Ca2+ exchange is retained when the exchanger is reconstituted into an asolectin bilayer, suggesting that this property is intrinsic to the protein and not dependent on species differences in lipid bilayer composition. Trout Na(+)-Ca2+ exchange is not markedly stimulated by alkaline pH, in contrast to mammals, and this characteristic is also maintained after reconstitution. Western blots of trout cardiac sarcolemma run on 7.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis react with antibodies raised against the canine Na(+)-Ca2+ exchanger with a similar pattern of bands (70, 120, and 160 kDa). Furthermore, a cDNA probe from canine Na(+)-Ca2+ exchanger hybridizes on Northern blots of trout heart mRNA to a 7-kb band, similar to that in mammals. Thus, while important functional differences in Na(+)-Ca2+ exchange exist between trout and mammalian hearts, the molecular basis is not yet known.</jats:p
The impact of fine sediments in small rivers : method development and effects on brown trout redds
No full textNative brown trout populations are declining in Swiss rivers. This could be due, among other reasons, to a clogged riverbed caused by fine sediment deposition, leading to a decrease in interstitial flow and therefore in a reduced oxygen supply to the salmonid embryos. Furthermore, suspended sediment (SS) could directly harm health and fitness of free swimming fish. The aim of this dissertation was to develop and apply methods to measure SS and the effects of weekly fine sediment infiltration and net fine sediment accumulation over the entire egg incubation season on oxygen concentrations in artificial redds and the survival of the implemented brown trout eggs. Furthermore, the effects of riverbed structure, redd morphology and hydrological and hydrogeological conditions on interstitial oxygen and egg survival was assessed. In addition, source areas of SS and organic matter were assessed by C/N atomic ratio, 13Ctot, 13Corg and 15N isotopes. The study was conducted at three sites named A, B and C, from up- to downstream along the canalized and partly stabilized river Enziwigger in the Swiss Plateau. Data were collected weekly or measured continuously during two spawning seasons (2009/10 and 2010/11) from November to March in a total of 36 redds.
Weekly fine sediment infiltration rates in redds were relatively high and generally increased with higher SS concentrations. Both, infiltrated sediments and SS showed strong temporal variations between low flow and peak discharge conditions. Fine sediment infiltration was at maximum during high flow events with sediments mainly in the size of sand (0.063 - 2 mm). These sediments originated for the most part in the upper watershed. Small amounts of fine sediments infiltrated during base flow periods with particles mainly in the size of silt and clay (< 63 µm) and with increasing organic matter concentrations. Organic matter was generally of allochthonous origin and major sediment source areas were pasture and arable land during those low flow periods.
Less fine sediment accumulated over the entire egg incubation period in upwelling zones on the local scale and within areas of higher mean water levels due to corresponding flushing of fine sediments. Even though SS and bedloads increased from up- to downstream, less fine sediment accumulated downstream. Higher flushing of fine sediments and generally increased sediment dynamics downstream due to higher water levels are probably the reasons for this observation. Increased sediment dynamics also caused remarkably scouring of redds: 50% of the redds in the two downstream sites were excavated or buried during high flow events in early winter due to sediment movements. Redd loss at the upstream site A was substantially lower (8%).
The high permeability of the redd substratum and the typical pit-tail structure of redds led to high dissolved oxygen (DO) concentrations in redds shortly after redd construction. Specific infiltration rates q decreased substantially within one month due to riverbed sediment displacements and fine sediment infiltration. This resulted in lower DO concentrations in redds. In individual redds, DO concentration decreased temporally to almost 0%, leading to a depleted redd environment unfavorable for embryo survival. Interstitial DO concentration and q generally increased during high flows. In contrast they decreased during the falling limb of the water level, likely indicating exfiltration of depleted ground- or interstitial water. Similarly, DO concentrations decreased under prolonged base flow conditions. This paralleled the higher percentage of silt and clay particles in the infiltrated sediment, probably triggering riverbed clogging and therefore reducing q.
Even though organic matter in SS increased from up- to downstream due to an increase of pasture and arable land downstream of the river, egg survival was better at the downstream sites. Organic matter concentrations were with means between 5.1% at site A and 6.5% at site C relatively low. The low egg survival at site A was likely due to the high fine sediment accumulation at the site, triggering low specific infiltration rates and consequently decreased DO concentrations. This was especially true at spots with low mean water levels, where flushing of fines is inhibited.
Enhanced soil erosion processes on pasture and arable land are expected with increasing heavy rain events and less snow during winter seasons due to climate change. Consequently, SS and organic matter in the river will increase, which will possibly affect brown trout negatively. Furthermore, a higher frequency of high flows in the future could potentially enhance scouring of redds especially in the downstream sites, which could further reduce egg survival rates
Variations on the Author
No full text“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
Flow Cytometric Enumeration of the Blood Cells of Rainbow Trout (Oncorhynchus mykiss) and New Zealand Freshwater Crayfish (Paranephrops planifrons)
No full textThe aim of this study was to develop flow cytometric (FC) methods to enumerate rainbow trout (Oncorhynchus mykiss) whole blood cells and New Zealand freshwater crayfish (Paranephrops planifrons) haemocytes as non-lethal endpoints in the evaluation of physiological status.
In the FC method development for rainbow trout, heparin was found to be superior to neutralised EDTA as a blood anticoagulant, because the use of EDTA resulted in significant lysis and shrinkage of erythrocytes. Leishman's-Giemsa and May Grunwald-Giemsa yielded comparable differential staining of leukocytes, and were superior to Wright-Giemsa staining. Morphological ambiguity between thrombocytes and lymphocytes in smears could not be resolved using Romanowsky or cytochemical staining. Use of FC was demonstrated to be a rapid, more accurate alternative to manual total cell counting procedures. Phosphate-buffered saline (PBS) was found to be superior to IsoTon II as a FC sheath fluid; IsoTon II induced lysis of erythrocytes. Characterisation of fish blood cell types and differentiation of leukocytes using FC could be achieved using 50 nM concentrations of the fluorescent lipophilic dye dihexyloxacarbocyanine iodide (DiOC6(3)), but inconsistent fluorescent behaviour exhibited by thrombocytes between specimens prevented clear resolution of these cells from erythrocytes and lymphocytes. Higher concentrations of DiOC6(3) did not enhance resolution and became cytotoxic, particularly to leukocytes. Resolution between thrombocytes and lymphocytes could only be achieved with a fluorescent-labelled thrombocyte monoclonal antibody (mAb). The results suggest that the application of FC and mAb to fish blood cells is the most accurate approach to differential counting of leukocytes.
The second FC method objectively characterised and enumerated New Zealand freshwater crayfish haemocytes. Haemocyte populations were isolated by FC sorting based on differential light scatter properties, followed by morphological characterisation by light microscopy and software image analysis. Cells were identified as hyaline, semi-granular and granular haemocytes based on established invertebrate haemocyte classification. A characteristic decrease in nuclear size and increase in granularity between the hyaline and granular cells, and the eccentric location of nuclei in granular cells were also observed. The granulocyte subpopulations were observed to possess varying degrees of granularity. The developed methodology was used to perform total and differential haemocyte counts from three lake crayfish populations and between wild and captive specimens. Differences in total and differential haemocyte counts were not observed between wild populations. However, specimens held in captivity for 14 d exhibited a significant 63% reduction in total haemocyte count, while the relative haemocyte proportions remained the same. These results demonstrate the utility of this method for the investigation of sub-acute stressor effects in selected decapod crustacea
High [Na+]i in cardiomyocytes from rainbow trout
No full textIntracellular Na+-concentration, [Na+]i modulates excitation-contraction coupling of cardiac myocytes via the Na +/Ca2+ exchanger (NCX). In cardiomyocytes from rainbow trout (Oncorhyncus mykiss), whole cell patch-clamp studies have shown that Ca2+ influx via reverse-mode NCX contributes signifi-cantly to contraction when [Na+]i is 16 mM but not 10 mM. However, physiological [Na+]i has never been measured. We recorded [Na+]i using the fluorescent indicator sodium-binding benzofuran isophthalate in freshly isolated atrial and ventricular myocytes from rainbow trout. We examined [Na+]i at rest and during increases in contraction frequency across three temperatures that span those trout experience in nature (7, 14, and 21°C). Surprisingly, we found that [Na+]i was not different between atrial and ventricular cells. Furthermore, acute temperature changes did not affect [Na +]i in resting cells. Thus, we report a resting in vivo [Na+]i of 13.4 mM for rainbow trout cardiomyocytes. [Na+]i increased from rest with increases in contraction frequency by 3.2, 4.7, and 6.5% at 0.2, 0.5, and 0.8 Hz, respectively. This corresponds to an increase of 0.4, 0.6, and 0.9 mM at 0.2, 0.5, and 0.8 Hz, respectively. Acute temperature change did not significantly affect the contraction-induced increase in [Na+]i. Our results provide the first measurement of [Na+]i in rainbow trout cardiomyocytes. This surprisingly high [Na+]i is likely to result in physiologically significant Ca2+ influx via reverse-mode NCX during excitation-contraction coupling. We calculate that this Ca 2+-source will decrease with the action potential duration as temperature and contraction frequency increases. Copyright © 2007 the American Physiological Society
Dimethyl-acetamide as a cryoprotectant for rainbow trout spermatozoa
No full textDimethyl-acetamide was evaluated as a cryoprotectant for rainbow trout (Oncorhynchus mykiss ) semen on the basis of motility, percentage of dead spermatozoa as determined by fluorometry, and fertility of frozen-thawed spermatozoa. Dimethyl-acetamide performed significantly better (P<0.05) than the conventional cryoprotectant, dimethyl sulfoxide, by all evaluation methods. An extender comprised of 0.137 M NaCl, 0.011 M KCl, 0.004 M Na(2)HPO(4) 7H(2)O, 7.5 g/l L-alpha-lecithin and 10 % DMA showed promise for cryopreserving rainbow trout spermatozoa. Future evaluation of new extenders should be carried out by several in vitro techniques and fertility measurements to present a complete assessment of an extender's ability to cryopreserve sperm cells.PUBM: Print; JID: 0421510; 1993/03/23 [received]; 1993/07/25 [accepted]; 1993/03/23 [received]; 1993/07/25 [accepted]; ppublishSource type: Electronic(1
A new role for carbonic anhydrase 2 in the response of fish to copper and osmotic stress: Implications for multi-stressor studies
No full textCopyright @ 2014 de Polo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article was made available through open access by the Brunel Open Access Publishing Fund.The majority of ecotoxicological studies are performed under stable and optimal conditions, whereas in reality the complexity of the natural environment faces organisms with multiple stressors of different type and origin, which can activate pathways of response often difficult to interpret. In particular, aquatic organisms living in estuarine zones already impacted by metal contamination can be exposed to more severe salinity variations under a forecasted scenario of global change. In this context, the present study aimed to investigate the effect of copper exposure on the response of fish to osmotic stress by mimicking in laboratory conditions the salinity changes occurring in natural estuaries. We hypothesized that copper-exposed individuals are more sensitive to osmotic stresses, as copper affects their osmoregulatory system by acting on a number of osmotic effector proteins, among which the isoform two of the enzyme carbonic anhydrase (CA2) was identified as a novel factor linking the physiological responses to both copper and osmotic stress. To test this hypothesis, two in vivo studies were performed using the euryhaline fish sheepshead minnow (Cyprinodon variegatus) as test species and applying different rates of salinity transition as a controlled way of dosing osmotic stress. Measured endpoints included plasma ions concentrations and gene expression of CA2 and the α1a-subunit of the enzyme Na+/K+ ATPase. Results showed that plasma ions concentrations changed after the salinity transition, but notably the magnitude of change was greater in the copper-exposed groups, suggesting a sensitizing effect of copper on the responses to osmotic stress. Gene expression results demonstrated that CA2 is affected by copper at the transcriptional level and that this enzyme might play a role in the observed combined effects of copper and osmotic stress on ion homeostasis
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