Reproductive Performance Of Fish Research Articles

Non-coding RNA Expression Patterns of Two Different Teleost Gonad Maturation Stages.

Non-coding RNAs (ncRNAs) are involved in several different regulatory pathways including reproduction. In teleost fish, efficacious reproduction is heavily dependent on the completion of the reproductive cycle. The presence of ncRNA, however, and their expression dynamics and putative regulatory role in mature and immature gonads have not yet been extensively explored. Therefore, the abundance of ncRNAs in mature and immature female sharpsnout seabream (Diplodus puntazzo) was investigated. The sharpsnout seabream is a rudimentary hermaphrodite which, in captivity, displays dysfunctions in the gonad maturation process. Our analyses revealed a gonad specific read length distribution with two main peaks representing miRNAs (21-26nt) and PIWI RNA (27-34nt). Besides, distinct expression patterns for several ncRNA biotypes including microRNAs (miRNAs), PIWI RNAs (piRNAs), and ribosomal RNAs (rRNAs) were detected. Identified miRNA accounted to 938, corresponding to ~ 13% of obtained transcripts. Among the differential expressed ncRNAs, 10 (~ 7%) were annotated as miRNA, out of which 2 were found in higher abundance in immature gonads (miR-125c and miR-24) and 8 (miR-451, miR-7a, miR-122-1, miR190a, miR129, ENSGACT00000029608, ENSGACT00000029489, and ENSGACT00000029667) were found to be higher expressed in mature gonads. Putative miRNA targets, including long non-coding RNAs (lncRNAs) and genes, are proposed. Target genes are involved in several processes of fish oocyte development, such as steroidogenesis, proteolysis, and apoptosis, and may explain hormone regulation. This study demonstrates a gonad maturation biased ncRNA profile which in turn may support the role of ncRNAs in ovarian physiology and reproductive performance of fish, stressing the specific function of each RNA biotype in oocyte development.

Exploring the Impact of a Low-Protein High-Carbohydrate Diet in Mature Broodstock of a Glucose-Intolerant Teleost, the Rainbow Trout.

Sustainable aquaculture production requires a greater reduction in the use of marine-derived ingredients, and one of the most promising solutions today is the augmentation in the proportion of digestible carbohydrates in aquafeed. This challenge is particularly difficult for high trophic level teleost fish as they are considered to be glucose-intolerant (growth delay and persistent postprandial hyperglycemia observed in juveniles fed a diet containing more than 20% of carbohydrates). It was previously suggested that broodstock could potentially use carbohydrates more efficiently than juveniles, probably due to important metabolic changes that occur during gametogenesis. To investigate this hypothesis, 2-year old male and female rainbow trout (Oncorhynchus mykiss) were either fed a diet containing no carbohydrates (NC) or a 35%-carbohydrate diet (HC) for an entire reproductive cycle. Zootechnical parameters as well as the activities of enzymes involved in carbohydrate metabolism were measured in livers and gonads. Fish were then reproduced to investigate the effects of such a diet on reproductive performance. Broodstock consumed the HC diet, and in contrast to what is commonly observed in juveniles, they were able to grow normally and they did not display postprandial hyperglycemia. The modulation of their hepatic metabolism, with an augmentation of the glycogenesis, the pentose phosphate pathway and a possible better regulation of gluconeogenesis, may explain their improved ability to use dietary carbohydrates. Although the HC diet did induce precocious maturation, the reproductive performance of fish was not affected, confirming that broodstock are able to reproduce when fed a low-protein high-carbohydrate diet. In conclusion, this exploratory work has shown that broodstock are able to use a diet containing digestible carbohydrates as high as 35% and can then grow and reproduce normally over an entire reproductive cycle for females and at least at the beginning of the cycle for males. These results are highly promising and suggest that dietary carbohydrates can at least partially replace proteins in broodstock aquafeed.

Effect of Probiotics on Reproductive Performance of Fish

Probiotics are defined as live microorganisms which when administered in adequate amounts, confer a health benefit on the host. Nowadays, Probiotics are used for eco-friendly and sustainable production in many production areas. They have also been common organisms that used in aquaculture as growth promoter, stress tolerance, pathogen inhibition, and nutrient digestibility, to increase water quality. Probiotics use in aquaculture comprehensively reviewed as an alternative to antibiotic treatment. However, very few studies have addressed the effects of probiotics on reproductive performance and gamete quality of fish. Thus, this review summarizes most current studies on the effects of probiotics on reproductive performance and gamete quality in fish and evaluates further applications of probiotics in reproduction of fish.

Effects of increasing temperature due to aquatic climate change on the self-fertility and the sexual development of the hermaphrodite fish, Kryptolebias marmoratus.

In order to assess the effects of increasing temperature on the reproductive performance of fish, different thermal conditions (i.e., 25.0, 26.5, 27.5, 28.5, 30.0°C) were used in this study and the self-fertilizing hermaphrodite fish, Kryptolebias marmoratus, was exposed to these different thermal conditions. During an exposure period of 30 to 150days, the gonadosomatic index (GSI), gonadal development, the levels of plasma 17β-estradial (E2) and testosterone (T), hepatic vitellogenin (VTG) mRNA abundance, and the number of self-fertilized eggs were analyzed. This study confirmed that a high water temperature above 27.5°C led to the suppression of self-fertility of hermaphroditic fish from 30days after exposure. The oocyte quality and maturation would be affected by the disruption of hepatic VTG synthesis at a high water temperature of 30°C, which resulted in the reduced the self-fertility in K. marmoratus. Consequently, this study suggests that elevated water temperature due to aquatic climate change prior to sexual maturation and the onset of spawning can lead to the reproductive dysfunction of hermaphroditic K. marmoratus.

Effect of vitamin-mineral supplemented diet and feeding strategies on reproductive performance of Labeo rohita broodstock

The present study was conducted to assess the effect of vitamin-mineral supplemented diet and feeding strategies on reproductive performance of fish (Labeo rohita). Two diets, with and without vitamin-mineral mixture supplementation, were fed to Labeo rohita yearlings for a period of 8 months (April-November) at two feeding rates i.e. 3 and 4% b.w. and two feeding frequencies i.e. once and twice day−1. The study revealed that ganado-somatic index and relative fecundity were significantly higher in diet supplemented with vitamin-mineral mixture @ 4% b.w. fed twice a day during both pre-spawning (July) and post-spawning i.e. at resorption (September). Absolute fecundity and ova diameter were equally higher in control and treatment diets supplemented @ 4% b.w. twice day−1. The study suggests that supplementation of vitamin-mineral mixtureat higher feeding rate and frequency improves reproductive potential of Labeo rohita broodstock.

Dietary fluted pumpkin (Telfairiaoccidentalis) improves reproductive indices in male African catfish (Clariasgariepinus) broodstock

Background: Medicinal plants/herbs are used as natural additives in fish diets to enhance reproductive performance in fish. Many studies have shown that antioxidants can enhance fertility either directly or indirectly and that most plants rich in antioxidants have the tendency to increase sperm count, motility, and enhance sperm morphology Method: The effects of dietary aqueous extract of fluted pumpkin (Telfairiaoccidentalis) leaf powder on growth and reproductive indices of male catfish, Clariasgariepinus bloodstocks was investigated.Four isonitrogenous diets were formulated from practical ingredients where the control basal diet (FPE1) was without aqueous extract of T. occidentalis leaf powder and the other diets were supplemented by 50, 100, 150 and 200 g kg_1 aqueous extract of T. occidentalis leaf powder respectively (designated as FPE2, FPE3, FPE4 and FPE5). The diets were manually fed to the broodstocks at a daily rate of 3% body weight (BW), twice a day (09:00 and 16:00 h) for 8 weeks. Fish were weighed collectively at biweekly intervals, their average weights were recorded and the daily amount of feed for each tank was readjusted accordingly. Result: Fish fed experimental diets showed significantly improved reproductive indices over the control fish. Significantly higher (P < 0.05) gonadosomatic index was recorded for the fish fed diets of aqueous extract of T. occidentalis leaf powder compared to fish fed on control diet. Conclusion: These results revealed that supplement diets with medicinal plant (T. occidentalis) improve gonadosomatic index, and reproductive indices of male C. gariepinusbroodstocks and these plant has a potential pro-fertility property which can be exploited in fish fingerling production by hatchery operators.

Reproductive traits of the spirlin Alburnoides bipunctatus in the Vistula River basin

The aim of the current study was to examine whether environmental conditions may explain interpopulation variation in fecundity and egg size of the spirlin from two rivers of the Vistula River basin. The obtained results indicated that the reproductive performance, including the gonadosomatic index, was similar in both rivers and fecundity increased with total length of females. The observed differences in water temperatures and flow speed between the rivers were too small to cause discernible differences in the reproductive performance of fish.

Effects of TDCPP or TPP on gene transcriptions and hormones of HPG axis, and their consequences on reproduction in adult zebrafish (Danio rerio)

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and triphenyl phosphate (TPP) belong to the group of triester organophosphate flame retardants (OPFRs), which have been used in a wide range of consumer products. These chemicals have been frequently detected in effluents, surface water, and fish, and hence their potential adverse effects on aquatic ecosystem are of concern. The present study was conducted to investigate the reproduction-related effects and possible molecular mechanisms of TDCPP and TPP using a 21 day reproduction test employing adult zebrafish (Danio rerio). After 21 d of exposure to TDCPP or TPP, significant decrease in fecundity along with significant increases of plasma 17β-estradiol (E2) concentrations, vitellogenin (VTG) levels, and E2/testosterone (T) and E2/11-ketotestosterone (11-KT) ratios were observed. The transcriptional profiles of several genes of the hypothalamus–pituitary–gonad (HPG) axis changed as well after the exposure, but the trend was sex-dependent. In male fish, gonadotropin-releasing hormone2 (GnRH2), GnRHR3, cytochrome P450 (CYP) 19B, estrogen receptor α (ERα), ER2 β1, and follicle stimulating hormone β (FSHβ) were upregulated in the brain, while luteinizing hormone β (LHβ) and androgen receptor (AR) were downregulated. Corresponding to the upregulation of FSHβ and downregulation of LHβ in the brain, FSHR was upregulated and LHR was downregulated in the testis. Among the genes that regulate the steroidogenesis pathway, transcription of hydroxyl methyl glutaryl CoA reductase (HMGRA), steroidogenic acute regulatory protein (StAR), and 17β-hydroxysteroid dehydrogenase (17βHSD) decreased, while transcription of CYP11A, CYP17, and CYP19A increased. In female fish, transcription ofGnRH2 and GnRHR3 decreased, but FSHβ, LHβ, CYP19B, ERα, ER2β1, and AR transcription increased in the brain. In the ovary, FSHR and LHR were significantly upregulated, and most steroidogenic genes were significantly upregulated. The observed disruption of GnRH and GtHs could be further related to subsequent disruption in both sex steroid hormone balance and plasma VTG levels, as well as reproductive performance. Overall, our observation indicates that both TDCPP and TPP could disturb the sex hormone balance by altering regulatory mechanisms of the HPG axis, eventually leading to disruption of reproductive performance in fish.

Food availability as a possible determinant for initiation and termination of reproductive activity in the tropical damselfish Chrysiptera cyanea

The involvement of food availability and temperature in the reproductive success was examined in a tropical damselfish Chrysiptera cyanea. Fish undergoing active reproduction were reared with saturated feed (SF; 1.5–2.0% of body mass) and limited feed (LF; one-tenth of SF) under natural photoperiod and temperature. Reduction of food ration affected spawning frequency during the reproductive season and spawning occurred repeatedly only under SF condition. The LF resulted in significant decreases in condition factor (K), hepatosomatic index (HSI), and gonadosomatic index (GSI) within 15 days with disappearance of vitellogenic oocytes from the ovaries. When the LF-reared fish were re-fed with SF, their K, HSI and GSI increased and vitellogenic oocytes re-appeared within 30 days. When these two feeding levels were crossed with 20, 25 and 30°C temperature regimes, the fish maintained better ovarian conditions at 25°C than those at 20 and 30°C, but not under LF conditions, suggesting that minimum and maximum temperatures in their habitat influence reproductive performance in fish. It is concluded that food availability is regarded as a regional factor in tropical monsoon environments and has an impact on reproductive success of tropical fish within suitable ranges in photoperiod and temperature conditions.

Altered reproduction in fish exposed to pulp and paper mill effluents: Roles of individual compounds and mill operating conditions

For the last 20 years, studies conducted in North America, Scandinavia, and New Zealand have shown that pulp and paper mill effluents affect fish reproduction. Despite the level of effort applied, few leads are available regarding the factors responsible. Effluents affect reproduction in multiple fish species, as evidenced by decreased gonad size, decreased circulating and gonadal production of reproductive steroids, altered expression of secondary sex characteristics, and decreased egg production. Several studies also have shown that effluent constituents are capable of accumulating in fish and binding to sex steroid receptors/ binding proteins. Studies aimed at isolating biologically active substances within the pulping and papermaking process have provided clues about their source, and work has progressed in identifying opportunities for in-mill treatment technologies. Following comparisons of manufacturing processes and fish responses before and after process changes, it can be concluded that effluent from all types of mill processes are capable of affecting fish reproduction and that any improvements could not be attributed to a specific process modification (because mills normally performed multiple modifications simultaneously). Improved reproductive performance in fish generally was associated with reduced use of molecular chlorine, improved condensate handling, and liquor spill control. Effluent biotreatment has been effective in reducing some effects, but biotreated effluents also have shown no difference or an exacerbation of effects. The role of biotreatment in relation to effects on fish reproduction remains unclear and needs to be resolved.

Evidence of Estrogenic Mixture Effects on the Reproductive Performance of Fish

Recent research into the effects of mixtures of estrogenic chemicals has revealed the capacity for similarly acting chemicals to act in combination, according to the principles of concentration addition. This means that, collectively, they may pose a significant environmental risk, even when each component is present at a low and individually ineffective concentration. The aim of this study was to investigate the ecological significance of mixture effects at low-effect concentrations by assessing the combined effect of estrogenic chemicals on the reproductive performance of fish. Pairs of fathead minnows were exposed to five estrogenic chemicals. Endpoints analyzed included fecundity, the expression of male secondary sexual characteristics, somatic indices, and vitellogenin induction. In the first phase of the study, a concentration-response analysis was performed to investigate the relative sensitivity of these endpoints. In the second phase, mixture effects at low-effect concentrations were explored by exposing fish to each of the mixture components, individually and in combination. Data from these experiments provide evidence of mixture effects on fitness and fecundity, demonstrating the capacity for chemicals to act together to affect reproductive performance, even when each component is present belowthe threshold of detectable effects. This has important implications for hazard assessment and contributes to our understanding of mixture effects at increasing levels of biological complexity.

Isolation of compounds from bleached kraft mill recovery condensates associated with reduced levels of testosterone in mummichog (Fundulus heteroclitus)

Previous studies have identified chemical recovery condensates as a primary source of hormonally active substances within a Canadian bleached kraft pulp mill. Although reverse osmosis treatment of condensates raises the exposure threshold that alters circulating levels of testosterone in mummichog (Fundulus heteroclitus), the responsible chemicals have not been characterized. In this study, a solid-phase extraction (SPE) method was developed to isolate chemical recovery condensate extractives for evaluation of hormonal activity. Condensates generated during softwood and hardwood pulp production were investigated for their relative potential to affect both circulating and gonadal production of sex steroids in mummichog. Mummichog were exposed to whole condensates, extracts from suspended particulates (> 1 microm), two fractions from SPE, and residual condensates after SPE. The distribution of bioactivity among condensate fractions was similar for both wood furnishes. In both sexes, significant depressions in circulating testosterone and in in vitro gonadal testosterone production were associated with exposure to whole condensates, particulate extracts, one SPE fraction, and residual material after SPE. An optimized SPE method subsequently demonstrated complete recovery of polar, bioavailable chemicals that reduced testosterone levels in both sexes. Characterizations of active fractions by gas chromatography-mass spectrometry (GC-MS) showed the presence of extractives with molecular masses > or = 240 amu possessing functionalities consistent with lignin degradation products. This study provides the first isolation of chemicals derived from pulp production associated with impaired reproductive performance in fish.

Contents and organ distribution of pantothenic acid in maturing turbot (Psetta maxima )

Contents and organ distribution of pantothenic acid in maturing turbot (<i>Psetta maxima</i> )

Effects of Diet or Liming on Steroid Hormone Metabolism and Reproduction in Atlantic Salmon (Salmo salar) Held in an Acidic River

Attempts to avert the impacts of an acidic river environment on Atlantic salmon (Salmo salar) were carried out in 1985 and 1986. Salmon were held in the Westfield River (pH 4.7–5.2) and the nearby Medway River (pH 5.3–5.6) during their sexual maturation. A diet containing 3% NaCl was fed to the Westfield salmon in 1985. Marble chips were used to elevate the pH of Westfield River water in 1986. Fish fed the salt diet had higher peak levels of plasma sex hormones, higher fecundity, greater incidence of spawners, lower egg mortality, and less weight loss than fish fed a commercial trout diet. The reproductive performance of fish held in limed water (pH 5.1–5.9) almost attained the level observed in the Medway (control) fish. Limestone treatment stimulated early peaking of blood androgen levels, testosterone, and 11-ketotestosterone in Westfield males, and 17α, 20β-dihydroxy-4-pregnen-3-one, a follicular mediator of gonadotropin, in a few Westfield females. The head kidneys produced more cortisol and corticosterone in all Westfield fish in both years compared to Medway fish. The results suggest that neither dietary salt nor liming completely prevented the decline of reproductive performance and the alteration of steroid hormone metabolism in salmon.