Does the rainbow trout ovarian fluid guide the spermatozoon on its way to the egg?

Fertilization of freshwater fish occurs in an environment that may affect negatively the gametes, therefore the specific mechanisms triggering the encounters of gametes would be highly expedient. The egg and ovarian fluid (OF) are likely the major sources of these triggers in fish, that we confirmed here for rainbow trout Oncorhynchus mykiss. The ovarian fluid affected significantly the spermatozoa performance: it supported high velocity for a longer period and changed the motility pattern from tumbling in water to straightforward moving in the ovarian fluid. Rainbow trout OF induced a trapping chemotaxis-like effect on activated male gametes and this effect depended on the properties of the activating media. The interaction of the sper-matozoa with the attracting agents was accompanied by their 'turn-and-run' behavior involving asymmetric flagellar beating and Ca2+ concentration bursts in the bent flagella segment, characteristic for the chemotactic response. Collectively, the ovarian fluid creates the optimal environment for rainbow trout spermatozoa performance, being an effective promoter of fertilization. The individual peculiarities of the egg (ovarian fluid)-sperm interaction in rainbow trout reflect the specific features of the spawning process in this species.

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Does the Rainbow Trout Ovarian Fluid Promote the Spermatozoon on Its Way to the Egg?

International Journal of Molecular Sciences ◽

10.3390/ijms22179519 ◽

2021 ◽

Vol 22 (17) ◽

pp. 9519

Author(s):

Vitaliy Kholodnyy ◽

Borys Dzyuba ◽

Marek Rodina ◽

Hermes Bloomfield-Gadêlha ◽

Manabu Yoshida ◽

...

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Freshwater Fish ◽

High Velocity ◽

Chemotactic Response ◽

Ovarian Fluid ◽

Motility Pattern ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Male Gametes ◽

The Individual

The fertilization of freshwater fish occurs in an environment that may negatively affect the gametes; therefore, the specific mechanisms triggering the encounters of gametes would be highly expedient. The egg and ovarian fluid are likely the major sources of these triggers, which we confirmed here for rainbow trout (Oncorhynchus mykiss). The ovarian fluid affected significantly spermatozoa performance: it supported high velocity for a longer period and changed the motility pattern from tumbling in water to straightforward moving in the ovarian fluid. Rainbow trout ovarian fluid induced a trapping chemotaxis-like effect on activated male gametes, and this effect depended on the properties of the activating medium. The interaction of the spermatozoa with the attracting agents was accompanied by the “turn-and-run” behavior involving asymmetric flagellar beating and Ca2+ concentration bursts in the bent flagellum segment, which are characteristic of the chemotactic response. Ovarian fluid created the optimal environment for rainbow trout spermatozoa performance, and the individual peculiarities of the egg (ovarian fluid)–sperm interaction reflect the specific features of the spawning process in this species.

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Post-ovulatory secretion of pituitary gonadotropins GtH I and GtH II in the rainbow trout (Oncorhynchus mykiss): regulation by steroids and possible role of non-steroidal gonadal factors

Journal of Endocrinology ◽

10.1677/joe.0.1630087 ◽

1999 ◽

Vol 163 (1) ◽

pp. 87-97 ◽

Cited By ~ 15

Author(s):

J Chyb ◽

T Mikolajczyk ◽

B Breton

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Body Cavity ◽

The Body ◽

Ovarian Fluid ◽

Multiple Injections ◽

Rainbow Trout Oncorhynchus Mykiss

In order to determine the factors of ovarian origin which can modulate the postovulatory secretion of the FSH-like gonadotropin (GtH I) and the LH-like gonadotropin (GtH II), freshly ovulated female rainbow trout were divided into two groups. In the first group the fish were stripped in order to eliminate the eggs and ovarian fluid from the body cavity, while in the second group the eggs were kept in the body cavity. Subsequently, fish from both groups were implanted with testosterone (10 mg/kg), 17beta-estradiol (10 mg/kg) or 17,20beta-ddihydroxy-4-regnen-3-one (17,20betaP) (1 mg/kg) or injected every 2 days with desteroidized ovarian fluid (1.5 ml/kg). The secretion of GtH I dramatically increased in stripped fish, reaching its maximum levels 2 weeks after ovulation. The preservation of eggs in the body cavity led to the suppression of this increase. The profiles of GtH II secretion were opposite to those encountered for GtH I because the increase of GtH II was observed only in unstripped fish. The administration of steroids showed that testosterone is able to inhibit GtH I release and stimulate that of GtH II in stripped fish, having no effect on the release of these gonadotropins in non-stripped animals. 17beta-Estradiol failed to modify GtH I secretion, however it decreased the release of GtH II in fish containing retained eggs in the body cavity. 17,20betaP had a delayed stimulating influence on GtH I release in unstripped fish. Finally, multiple injections of desteroidized ovarian fluid into stripped fish led to a significant decrease of GtH I release and to an increase of GtH II secretion. This study demonstrates that factors, which are present in ovarian fluid, modulate the post-ovulatory secretion of both gonadotropins--their net action is negative on GtH I and positive on GtH II. Among the steroids, testosterone is of major importance, being able to inhibit GtH I release and to stimulate that of GtH II. We also show that non-steroidal factors present in the ovarian fluid can influence the release of both gonadotropins, which indirectly supports the previous findings about the existence of inhibin/activin-like factors in fish.

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Tissue-specific Cu bioaccumulation patterns and differences in sensitivity to waterborne Cu in three freshwater fish: rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio), and gibel carp (Carassius auratus gibelio)

Aquatic Toxicology ◽

10.1016/j.aquatox.2004.07.001 ◽

2004 ◽

Vol 70 (3) ◽

pp. 179-188 ◽

Cited By ~ 58

Author(s):

Gudrun De Boeck ◽

Wouter Meeus ◽

Wim De Coen ◽

Ronny Blust

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Freshwater Fish ◽

Cyprinus Carpio ◽

Carassius Auratus ◽

Gibel Carp ◽

Carassius Auratus Gibelio ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Common Carp Cyprinus Carpio ◽

Carp Cyprinus Carpio

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Short communication: Response of rainbow trout (Oncorhynchus mykiss) to mirror images

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2017151-10136 ◽

2017 ◽

Vol 15 (1) ◽

pp. e05SC02

Author(s):

Wendy M. Rauw ◽

Luis A. García-Cortés ◽

Morris Villarroel ◽

Luis Gomez-Raya

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Short Communication ◽

Behavioural Response ◽

The Other ◽

Coping Response ◽

Aggressive Interactions ◽

Aquarium Fish ◽

Rainbow Trout Oncorhynchus Mykiss ◽

The Individual

The response of cultured rainbow trout to their mirrored image was investigated. Thirty fish were placed individually in two novel aquariums consecutively for 10 min each. Walls in one aquarium were covered with mirrors on all four sides, whereas the walls of the other aquarium were non-transparent black. Because all four walls were covered with mirrors, the mirrored image of the fish was reproduced multiple times such that ‘a group’ of fish was created surrounding the individual. Half of the fish started in the aquarium with the mirrors, whereas the other half started in the mirrorless aquarium. Fish swim faster in the aquarium with mirrors than in the mirrorless aquarium (2.95 vs. 2.40 cm/s; p < 0.01), indicating a positive behavioural response towards their mirrored images. Fish did not show aggressive interactions towards their mirrored images. Being confronted with ‘a group’ of fish and not just one ‘opponent’ may have inhibited aggressive behavior, or individuals may not have considered the images to be fellow individuals. Fish that swam faster in the mirrorless aquarium also did so in the aquarium with mirrors (r = 0.73; p < 0.0001), indicating a persistent behavioural coping response (boldness) in response to the two novel environments. Mirrors may be used to influence social behaviour of fish in aquaculture; further research is needed to investigate the influence of mirror placement in tanks of group housed trout on growth and behaviour.

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Trade-Offs Underwater: Physiological Plasticity of Rainbow Trout (Oncorhynchus mykiss) Confronted by Multiple Stressors

Fishes ◽

10.3390/fishes3040049 ◽

2018 ◽

Vol 3 (4) ◽

pp. 49 ◽

Cited By ~ 4

Author(s):

Elena Wernicke von Siebenthal ◽

Kristina Rehberger ◽

Christyn Bailey ◽

Albert Ros ◽

Elio Herzog ◽

...

Keyword(s):

Resource Allocation ◽

Rainbow Trout ◽

Phenotypic Plasticity ◽

Oncorhynchus Mykiss ◽

Multiple Stressors ◽

Parasitic Infection ◽

Phenotypic Flexibility ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Trade Offs ◽

The Individual

Organisms have evolved mechanisms to partition the available resources between fitness-relevant physiological functions. Organisms possess phenotypic plasticity to acclimate to changing environmental conditions. However, this comes at a cost that can cause negative correlations or “trade-offs”, whereby increasing investments in one function lead to decreased investments in another function. The aim of the present study was to investigate the prioritization of resource allocation between growth, pathogen defense, and contaminant response in juvenile rainbow trout (Oncorhynchus mykiss) exposed to changes of resource income or expenditure. We performed a multifactorial experiment with three resource-impacting stressors—limited food availability, a parasitic infection, exposure to a vitellogenesis-inducing contaminant—and combinations thereof. Treatment with the individual stressors evoked the expected responses in the respective physiological target systems—body growth, immune system, and hepatic vitellogenin transcription—but we found little evidence for significant negative relations (trade-offs) between the three systems. This also applied to fish exposed to combinations of the stressors. This high phenotypic flexibility of trout in their resource allocation suggests that linear resource allocations as mechanisms of phenotypic plasticity may be too simplistic, but it also may point to a greater capacity of ectothermic than endothermic vertebrates to maintain key physiological processes under competing resource needs due to lower maintenance costs.

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Long-term monitoring of the individual self-feeding behavior of rainbow trout Oncorhynchus mykiss

Journal of Oceanology and Limnology ◽

10.1007/s00343-019-8020-5 ◽

2018 ◽

Vol 37 (1) ◽

pp. 344-349

Author(s):

Ce Shi ◽

Xiaolong Gao ◽

Ying Liu ◽

Chunlin Wang

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Feeding Behavior ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Long Term Monitoring ◽

The Individual ◽

Individual Self ◽

Term Monitoring

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Biomagnification of ionizable organic compounds in rainbow trout Oncorhynchus mykiss

Environmental Sciences Europe ◽

10.1186/s12302-020-00443-1 ◽

2020 ◽

Vol 32 (1) ◽

Author(s):

Carolin Mueller ◽

Stefan Trapp ◽

Fabio Polesel ◽

Sebastian Kuehr ◽

Christian Schlechtriem

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Organic Compounds ◽

Half Life ◽

Assimilation Efficiency ◽

Test Results ◽

Rainbow Trout Oncorhynchus Mykiss ◽

The Individual ◽

Strong Acids ◽

Depuration Rate

Abstract Background The assessment of persistence, bioaccumulation and toxicity (PBT) is part of the regulation process of ionic organic compounds (IOCs) and a major challenge, as a commonly acknowledged approach for the estimation of the bioaccumulation potential of IOCs is still missing. The goal of the present study was, therefore, to experimentally determine the bioaccumulation of fully ionized compounds and to identify screening parameters that can indicate high bioaccumulation potential of IOCs. Three feeding studies with rainbow trout (Oncorhynchus mykiss) were carried out according to OECD TG 305. Separation of liver, gastrointestinal tract (GIT) and carcass allowed to further elucidate the tissue distribution of the individual test substances. The chemicals chosen had characteristics that made them suspect for high bioaccumulation, and included two cations (tetrabutylphosphonium bromide (TBP), trimethyloctadecyl ammonium chloride (TMOA)) and four anions (benzotriazole, tecloftalam, pentachlorophenol (PCP), MEE-phosphonate). Data on the dietary biomagnification of IOCs (strong acids) were also collected from published literature. Results The highest distribution factors were found for the GIT, followed by liver. However, none of the tested IOCs showed a distinct biomagnification potential, as kinetic biomagnification factors (BMFk) ranged between 0.001 and 0.05 g/g (median 0.009 g/g). Cations showed lower assimilation efficiency (α) than anions, except for tecloftalam. In contrast, anions showed a considerably faster depuration rate (half-life less than 0.5 days) compared to cations (half-life of around 5 days). Sixteen potential screening parameters for BMF were calculated with a chemical property estimation tool (ACD/i-Lab) and correlated with the BMF data from this study and from literature. The number of hydrogen bond donors (nHBD) showed the highest correlation to measured BMF, but the prediction is only based on two values (one or two nHBD), while the other descriptors were insignificantly correlated. Conclusion The suspected dietary bioaccumulation potential of the six IOCs could not be confirmed in the feeding studies with rainbow trout. The more than twenty screening parameters showed no particularly high correlation neither with the test results nor with the BMF values collected from literature. The results corroborate earlier findings that ionization lowers the tendency of a chemical for dietary bioaccumulation, compared to non-ionized chemicals. In addition to the lipophobicity of ionic molecule moieties, fast depuration seems to be a major reason for the observed low dietary bioaccumulation of ionic compounds, in particular anions. Fast depuration may happen due to rapid metabolism of charged compounds, and future studies should test this hypothesis.

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