Relationship between hepatic deiodination of thyroxine and early oocyte development in rainbow trout, Oncorhynchus mykiss

We examined the relationship between five stages of ovarian growth and development and hepatic microsomal thyroxine (T4) deiodinating activity in rainbow trout, Oncorhynchus mykiss, held in the laboratory at 11.5°C. Thyroxine outer-ring deiodination (T4ORD) activity, which forms biologically active 3,5,3'-triiodothyronine (T3), was low when the gonadosomatic index (GSI = (ovary mass X 100) / body mass) was below 0.2 (stage I, previtellogenesis), but rose sharply between GSI values of 0.2 and 0.3 (stage II), when oocyte Balbiani activity, RNA synthesis, and endogenous vitellogenesis were maximal. Hepatic T4ORD activity was again low during exogenous vitellogenesis at GSI values of 0.3-12, which correspond to stages III-V. Hepatic T4 inner-ring deiodination (T4IRD), which forms biologically inactive 3,3',5'-triiodothyronine, was detected only at stage II. Plasma T3 concentrations were significantly higher at stage II than at stage IV (primary yolk globule formation). Our data indicate changes in systemic thyroidal status at stage II and are consistent with a role for T3 in early oogenesis in trout. Enhanced hepatic T3 production at the late Balbiani stage may be required for oocyte development.

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Transition from a hatchery to a laboratory environment induces inner-ring monodeiodination pathways for thyroid hormones in liver of rainbow trout, Oncorhynchus mykiss

Canadian Journal of Zoology ◽

10.1139/z96-246 ◽

1996 ◽

Vol 74 (12) ◽

pp. 2178-2183 ◽

Cited By ~ 12

Author(s):

C. E. Johnston ◽

C. Gordillo ◽

J. G. Eales

Keyword(s):

Rainbow Trout ◽

Thyroid Hormones ◽

Oncorhynchus Mykiss ◽

Time Frame ◽

Biologically Active ◽

Outer Ring ◽

Physical Disturbance ◽

Laboratory Environment ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Thyroidal Status

In laboratory-acclimated rainbow trout (Oncorhynchus mykiss) the main hepatic deiodination pathway for thyroid hormones is L-thyroxine (T4) outer-ring deiodination (T4ORD), which produces biologically active 3,5,3′-triiodo-L-thyronine (T3); T4 inner-ring deiodination (T4IRD) as well as T3ORD and T3IRD activities are low or undetectable. Surprisingly, trout transported 48 h previously from a local hatchery to the laboratory demonstrated not only low T4ORD activity but also significant T4IRD and T3IRD activities. To test if the transition from hatchery to laboratory environment had induced the unexpected inner-ring deiodinations, we measured hepatic deiodinase activities over the same time frame in trout recently transported to the laboratory and also in trout retained undisturbed at the hatchery. Undisturbed hatchery trout showed typical hepatic deiodinase function: T4ORD activity predominated, while T3IRD, T4IRD, and T3ORD activities were basal. However, after 1–3 days in the laboratory, hepatic T4ORD activity was reduced and T4IRD and T3IRD activities were increased. By 5 days, deiodinase activities of laboratory trout reverted to the levels of hatchery trout. We conclude that physical disturbance can temporarily depress thyroidal status by simultaneously decreasing hepatic production of biologically active T3 and inducing degradation of T4 and T3.

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Saving energy to fuel exercise: swimming suppresses oocyte development and downregulates ovarian transcriptomic response of rainbow trout Oncorhynchus mykiss

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00109.2010 ◽

2010 ◽

Vol 299 (2) ◽

pp. R486-R499 ◽

Cited By ~ 11

Author(s):

Arjan P. Palstra ◽

Diego Crespo ◽

Guido E. E. J. M. van den Thillart ◽

Josep V. Planas

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Sexual Maturation ◽

Protein Biosynthesis ◽

Microarray Platform ◽

Oocyte Development ◽

Long Distance ◽

Transcriptomic Response ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Reproductive Migration

Metabolic processes and sexual maturation closely interact during the long-distance reproductive migration of many fish species to their spawning grounds. In the present study, we have used exercise experimentally to investigate the effects on sexual maturation in rainbow trout. Pubertal autumn-spawning seawater-raised female rainbow trout Oncorhynchus mykiss ( n = 26; 50 cm, 1.5 kg) were rested or swum at a near optimal speed of 0.75 body lengths per second in a 6,000-liter swim flume under natural reproductive conditions (16°C fresh-water, starvation, 8:16-h light-dark photoperiod). Fish were sampled after arrival and subsequently after 10 days (resting or swimming 307 km) and 20 days (resting or swimming 636 km). Ovarian development was significantly reduced in the swimmers. Analysis of the expression of key factors in the reproductive axis included pituitary kiss1-receptor, lh, and fsh and ovarian lh-receptor, fsh-receptor, aromatase, and vitellogenin-receptor ( vtgr). Swimmers had lower pituitary lh and ovarian vtgr expression than resters. Furthermore, the number of late vitellogenic oocytes was lower in swimmers than in resters, probably resulting from the lower vtgr expression, and vitellogenin plasma levels were higher. Therefore, swimming exercise suppresses oocyte development possibly by inhibiting vitellogenin uptake. Transcriptomic changes that occurred in the ovary of exercised fish were investigated using a salmonid cDNA microarray platform. Protein biosynthesis and energy provision were among the 16 functional categories that were all downregulated in the ovary. Downregulation of the transcriptomic response in the ovary illustrates the priority of energy reallocation and will save energy to fuel exercise. A swimming-induced ovarian developmental suppression at the start of vitellogenesis during long-term reproductive migration may be a strategy to avoid precocious muscle atrophy.

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Evaluation of the composition of essential fatty acids in the tissues of rainbow trout (Oncorhynchus mykiss) grown in closed water supply units

Proceedings of the Zoological Institute RAS ◽

10.31610/trudyzin/2021.325.4.495 ◽

2021 ◽

Vol 325 (4) ◽

pp. 495-501

Author(s):

E.A. Zykina ◽

M.V. Gurin

Keyword(s):

Fatty Acids ◽

Rainbow Trout ◽

Water Supply ◽

Oncorhynchus Mykiss ◽

Fish Oil ◽

Essential Fatty Acids ◽

The Body ◽

Biologically Active ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Aquaculture Products

Recently, the task of artificial cultivation of especially valuable fish species in aquaculture has become more and more urgent. The value of salmon fish, and in particular rainbow trout Oncorhynchus mykiss (Walbaum, 1792) available for breeding, is largely determined by the high content of biologically active essential and polyunsaturated fatty acids of the group ω-6 and ω-3, necessary for vital activity and not synthesized by the human body. Since the natural stocks of many popular fatty fish have decreased, farmed fish can help meet consumer demand for this product. Based on this, the assessment of the content of the main ω-6 and ω-3 fatty acids in the fat of rainbow trout grown in closed-loop water supply installations (USV) was made. The fat was extracted from the fish by thermal method with further distillation by supercritical fluid extraction on the SFT-150 unit. The ratio of fatty acids in the fish oil sample was determined using the Chromatek-Kristall-5000 M hardware and software complex. The results obtained were compared with the standard for salmon fish oil “Aquaculture products” and “Wild fish”. It is established that trout cultivated in the UZV in the Penza region, in terms of the content of the main essential fatty acids, is not inferior to the quality indicators of the standard in terms of the requirements for salmon fish of “Aquaculture products”. In fish, all essential fatty acids are present in sufficient quantities, the ratio of ω-6 to ω-3 is 2.6:1, which indicates a high nutritional value of the product and allows it to be used in human food to provide the body with essential fatty acids, as well as a raw material for obtaining therapeutic and preventive products.

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