Changes in the plasma levels of insulin-like growth factor-I from the onset of spawning migration through upstream migration in chum salmon

Onuma, Takesh I. A.; Makino, Keit A.; Katsumata, Hiro Shi; Beckman, Brian R.; Ban, Masatoshi; Ando, Hironori; Fukuwaka, Masa‐aki; Azumaya, Tomonori; Swanson, Penny; Urano, Akihisa

doi:10.1016/j.ygcen.2009.07.005

Cited by 19 publications

(7 citation statements)

References 27 publications

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“…These salmon studies only examined juvenile fish; in contrast, the lingcod examined in this study included both juvenile and adult fish. Several fieldwork studies have shown that factors related to season, size of individual, and stage of maturity (Onuma et al 2010;Beaudreau et al 2011) explain some of the variation in IGF1 in wild fish. Further work to determine how lingcod IGF1 levels vary with these factors may be necessary to judge when it is appropriate to directly compare IGF1 values between groups of fish in the field to infer differences in growth rate (i.e., Can males and females or individuals in different stages of maturity be considered together?…”

Section: Discussionmentioning

confidence: 99%

Suitability of Insulin‐Like Growth Factor 1 (IGF1) as a Measure of Relative Growth Rates in Lingcod

et al. 2011

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The effectiveness of spatial management strategies is typically evaluated through traditional biological measurements of size, density, biomass, and the diversity of species inside and outside management boundaries. However, there have been relatively few attempts to evaluate the processes underlying these biological patterns. In this study, we take the first step toward developing a relative index of body growth for lingcod Ophiodon elongatus using plasma insulin‐like growth factor 1 (IGF1) with the ultimate goal of measuring spatial differences in relative growth rates. Insulin‐like growth factor 1 is one of the principal hormones that stimulates growth at the cellular level in all vertebrates and shows significant relationships with body growth in many fishes. In the laboratory, we found that the level of IGF1 was related to the instantaneous growth of juvenile lingcod. In the field, we measured size, condition, and plasma IGF1 level in 149 lingcod from eight locations inside and outside marine protected areas in the San Juan Islands, Washington. The IGF1 levels in wild lingcod were highly variable from site to site for both genders, and we were able to detect differences in IGF1 across space in males. Multivariate analyses showed that the spatial patterns of IGF1 differed from those of traditional biological measurements. More work is needed to validate the relationship between IGF1 and growth in larger individuals, but our research shows the potential for IGF1 to be used as an ecological indicator.

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Section: Discussionmentioning

confidence: 99%

Suitability of Insulin‐Like Growth Factor 1 (IGF1) as a Measure of Relative Growth Rates in Lingcod

et al. 2011

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“…Just recently, studies have been initiated that have partly investigated the interaction between metabolism and sexual maturation in wild chum salmon (Oncorhynchus keta Walbaum) (42,43,44) just before their spawning migration and in wild sockeye salmon (Oncorhynchus nerka Walbaum) during their spawning migration (40). Onuma et al (42,43,44) showed that fsh␤ and lh␤ pituitary mRNA, plasma testosterone (T), 11-ketotestosterone, and 17␤-estradiol (E 2 ) levels were increased in maturing chum salmon that were about to start migration.…”

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confidence: 99%

“…Onuma et al (42,43,44) showed that fsh␤ and lh␤ pituitary mRNA, plasma testosterone (T), 11-ketotestosterone, and 17␤-estradiol (E 2 ) levels were increased in maturing chum salmon that were about to start migration. Plasma IGF-I levels were higher in these fish indicating that IGF-I may act as somatotropic signal in stimulating the pituitary-gonad axis.…”

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

Palstra

Crespo

Thillart

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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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 degrees 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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“…This expression profile is consistent with plasma FSH [26,27] and IGF1 profiles in female coho salmon [27,29] and our results indicate that both of these hormones stimulate ovarian cx34.3 expression in vitro . Plasma levels of FSH [26] and IGF1 [28] in salmon decrease at final oocyte maturation, while plasma LH levels increase during this period [26]. Our results indicate that at this stage, LH increased expression of cx34.3 .…”

Section: Discussionmentioning

confidence: 75%

The spatiotemporal expression of multiple coho salmon ovarian connexin genes and their hormonal regulation in vitro during oogenesis

Yamamoto

Luckenbach

Middleton

et al. 2011

Reprod Biol Endocrinol

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BackgroundThroughout oogenesis, cell-cell communication via gap junctions (GJs) between oocytes and surrounding follicle cells (theca and granulosa cells), and/or amongst follicle cells is required for successful follicular development. To gain a fundamental understanding of ovarian GJs in teleosts, gene transcripts encoding GJ proteins, connexins (cx), were identified in the coho salmon, Oncorhynchus kisutch, ovary. The spatiotemporal expression of four ovarian cx transcripts was assessed, as well as their potential regulation by follicle-stimulating hormone (FSH), luteinizing hormone (LH) and insulin-like growth factor 1 (IGF1).MethodsSalmonid ovarian transcriptomes were mined for cx genes. Four gene transcripts designated cx30.9, cx34.3, cx43.2, and cx44.9 were identified. Changes in gene expression across major stages of oogenesis were determined with real-time, quantitative RT-PCR (qPCR) and cx transcripts were localized to specific ovary cell-types by in situ hybridization. Further, salmon ovarian follicles were cultured with various concentrations of FSH, LH and IGF1 and effects of each hormone on cx gene expression were determined by qPCR.ResultsTranscripts for cx30.9 and cx44.9 were highly expressed at the perinucleolus (PN)-stage and decreased thereafter. In contrast, transcripts for cx34.3 and cx43.2 were low at the PN-stage and increased during later stages of oogenesis, peaking at the mid vitellogenic (VIT)-stage and maturing (MAT)-stage, respectively. In situ hybridization revealed that transcripts for cx34.3 were only detected in granulosa cells, but other cx transcripts were detected in both oocytes and follicle cells. Transcripts for cx30.9 and cx44.9 were down-regulated by FSH and IGF1 at the lipid droplet (LD)-stage, whereas transcripts for cx34.3 were up-regulated by FSH and IGF1 at the LD-stage, and LH and IGF1 at the late VIT-stage. Transcripts for cx43.2 were down-regulated by IGF1 at the late VIT-stage and showed no response to gonadotropins.ConclusionOur findings demonstrate the presence and hormonal regulation of four different cx transcripts in the salmon ovary. Differences in the spatiotemporal expression profile and hormonal regulation of these cx transcripts likely relate to their different roles during ovarian follicle differentiation and development.

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Changes in the plasma levels of insulin-like growth factor-I from the onset of spawning migration through upstream migration in chum salmon

Cited by 19 publications

References 27 publications

Suitability of Insulin‐Like Growth Factor 1 (IGF1) as a Measure of Relative Growth Rates in Lingcod

Suitability of Insulin‐Like Growth Factor 1 (IGF1) as a Measure of Relative Growth Rates in Lingcod

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

The spatiotemporal expression of multiple coho salmon ovarian connexin genes and their hormonal regulation in vitro during oogenesis

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