Long-term effects of intraperitoneal injection of estradiol-17β on the growth and physiology of juvenile stellate sturgeon Acipenser stellatus

Effects of dietary supplementation of estradiol-17β during fry stage on growth, physiological and immune parameters and gonadal gene expression in adult snakeskin gourami

In snakeskin gourami (Trichopodus pectoralis), females are generally larger than males, and estradiol-17β (E2)-sex reversal to produce female monosex has gained interest in this species. In this study, we aimed to investigate the effects of E2-induced sex reversal on growth, physiological and immune parameters, and gonadal gene expression in adult snakeskin gourami. Fry (7 days posthatching) were divided into different experimental groups based on the dose of E2: control (no E2 (0 mg kg-1) supplementation), E2-100 (100 mg kg-1), E2-200 (200 mg kg-1), and E2-300 (300 mg kg-1), fed with the E2 doses for 90 d and cultured for 11 months (adult stage). The findings revealed that E2 supplementation produced 88.89-100% of female population. After 11 months of culture, the effects of sexual dimorphism on the growth performance of the E2-100 group were not significant compared to that on the growth performance of the control male and female groups; however, it improved significantly in the E2-200 and E2-300 groups (P < 0.05). E2 elevated the CP and fat contents in body in E2-200 and E2-300 groups (P < 0.05) compared to that in the control group. No sex differences in blood metabolites, haematological values, or immune parameters were identified. Nevertheless, E2-200 and E2-300 groups showed increased blood glucose, triglyceride, haemoglobin, and total immunoglobulin (P < 0.05) compared to control male fish. In addition, all concentrations of E2 increased alternative complement 50 (P < 0.05). Several genes, including bHLH, cyp19a1, daz, deadend, esrb, esrrg, gnrhr, gpa, gsg1l, hsd17β, mospd1, nanos2, p53, piwi2, rerg, rps6ka, tgfb, and vgr, showed differential expression between testis and ovary in control female and E2-treated groups. The expression patterns of the genes were similar in the ovary of the control female and E2-200-treated fish. In conclusion, the findings demonstrate that a feminisation duration of 7-97 days and two doses of E2 at 200 or 300 mg kg-1 successfully produced all-female stocks in snakeskin gourami. Furthermore, the findings showed that E2-treated females were maintained throughout adulthood and exhibited several superior characteristics to male fish. Together with the information generated on differentially expressed sex-related genes, these findings could enable the culturing of faster-growing sex to increase productivity and contribute to the development of intensive snakeskin gourami farming.

Effects of calcium and estrogen on the development of the ceratohyal cartilage in zebrafish (Danio rerio) larvae upon embryo and maternal cadmium exposure

The present study is to investigate the reason why the ceratohyal cartilage (CH) angle of zebrafish larvae were larger compared to the control group after their female parents were treated with cadmium (F-Cd). However, the CH angle was smaller compared to the control group when embryos were directly exposed to Cd²⁺ for 72 h (D-Cd). Results showed that calcium contents of larvae were lower than the control, but the transporter isoforms trpv4 and trpv6 mRNA expressions were significantly increased upon D-Cd treatment. Furthermore, external Ca²⁺ added during D-Cd treatment reveals that the CH angles of larvae did not appear significantly different compared to the control. On the other hand, E2 (17β-estradiol) contents were higher around 1.9 folds in the ovaries of females; CH angle were over 25°, and Cd²⁺ contents were higher around 6 folds than the control group on larvae treated through F-Cd treatment; CH angles and E2 levels on larvae were higher than the control after the larvae were treated with 1.84 μM E2 (D-E2); Estradiol receptor (ER) isoforms ERβ1 and ERα mRNA expressions significantly increased when 0 hpf embryos were either treated with D-E2 or D-Cd. According to the results, we suggested that the CH angle of larvae become larger upon F-Cd treatment due to maternal Cd²⁺ inducing E2 levels. However, the CH angle of larvae appeared to be smaller compared to the control upon D-Cd treatment. We suggested that the CH angle decreased due to the decrease of Ca²⁺ contents upon Cd²⁺ exposure.

Effects of alpha-ketoglutarate (AKG) on growth performance and non-specific immunity of juvenile red drum fed diets with low or adequate phosphorus levels

This study evaluated the effects of α-ketoglutarate (AKG) on the growth performance, body, and skeletal composition, as well as non-specific immunity of juvenile red drum (Sciaenops ocellatus) fed adequate or low-phosphorus diets. A 2 × 2 factorial design was arranged with two levels of total phosphorus (1.0 or 1.6%) and two levels (0 or 1%) of AKG. Each diet was fed to red drum in four replicate 110-L aquaria (15 fish/aquarium) twice daily for 7 weeks. The results indicated that the low-P diets significantly (P < 0.05) decreased weight gain, feed efficiency, and condition factor of red drum, but increased moisture content and decreased ash content of whole body, as well as decreased ash content of skeletal tissue and decreased plasma lysozyme. Supplementation of AKG significantly improved the fillet yield and plasma lysozyme and tended to improve neutrophil oxidative radical production (P = 0.097). Based on these results, phosphorus level had the greatest effect on growth performance and non-specific immunity of red drum, while AKG supplementation had limited positive effects on immunological responses and fillet yield of juvenile red drum.

Do environmental factors affect male fathead minnow (Pimephales promelas) response to estrone? Part 1. Dissolved oxygen and sodium chloride

Laboratory exposures indicate that estrogens and their mimics can cause endocrine disruption in male fishes, yet while studies of resident fish populations in estrogen-polluted waters support these findings, biomarker expression associated with field versus laboratory exposure to estrogenic endocrine disruptors (EDs) often differ dramatically. Two of the environmental parameters often found to vary in dynamic aquatic ecosystems were chosen (dissolved oxygen [DO] and sodium chloride concentrations) to assess their potential impact on ED exposure. In separate experiments, male fathead minnows (Pimephales promelas) were exposed to estrone (E1) a natural ED, under either two concentrations of DO, or two concentrations of sodium chloride, in a laboratory flow-through system. Morphological and hematological parameters were assessed. While vitellogenin concentrations were elevated with exposure to estrone (29 to 390ng/L), the effect on other indices were variable. Estrone exposure altered SSC, blood glucose, hematocrit, and hepatic and gonado-somatic index in 1 of 4 experiments, while it decreased body condition factor in 3 of 4 experiments. At the concentrations tested, no main effect differences (P<0.05) were found associated with DO or sodium chloride treatments, except in one experiment low DO resulted in a decrease in secondary sex characteristic score (SSC). The combination of DO or sodium chloride and E1 altered blood glucose in one experiment each. These results indicate the variability of fathead minnow response to estrone, even within the confines of controlled laboratory conditions.

Short-term effects of 17β-estradiol on physiological responses in stellate sturgeon Acipenser stellatus

There is no evidence of the effect of 17β-estradiol (E2) administration on stress response and related metabolites after a short-period in chondrostean. In this study, we examined whether E2 is capable of inducing the hypothalamus-pituitary-interrenal axis activity. To accomplish this, sexually immature Acipenser stellatus were injected intraperitoneally with saline or E2 (5mg/kg body mass) and sampled 0, 1, 3, 6, 12, 24, 48, and 72h later. Plasma E2, cortisol, glucose, lactate, hematocrit (Hct), total protein (TP), cholesterol, triglyceride, alkaline phosphatase activity (ALP), calcium (Ca), and phosphorus concentrations were examined. Plasma levels of E2 significantly increased after 1h in E2-injected fish and remained high after 12h. E2 injection enhanced plasma TP and Ca concentrations, but had no effect on other parameters. Injection of either saline or E2 enhanced plasma glucose, lactate, TP, and Ca concentrations, but had no effect on Hct, cholesterol, triglyceride, and ALP. The results demonstrated that acutely elevated level of E2 did not lead to intense changes of stress metabolites and altered biochemical changes compared to the fish in control or saline treatment groups. Therefore, we found no exhibition of E2 on the rate of cortisol synthesis or stress indicators in this species, while E2 could modulate some other related metabolites on vitellogenesis pathway.

De novo Assembly and Analysis of the Chilean Pencil Catfish Trichomycterus areolatus Transcriptome

Trichomycterus areolatus is an endemic species of pencil catfish that inhabits the riffles and rapids of many freshwater ecosystems of Chile. Despite its unique adaptation to Chile's high gradient watersheds and therefore potential application in the investigation of ecosystem integrity and environmental contamination, relatively little is known regarding the molecular biology of this environmental sentinel. Here, we detail the assembly of the Trichomycterus areolatus transcriptome, a molecular resource for the study of this organism and its molecular response to the environment. RNA-Seq reads were obtained by next-generation sequencing with an Illumina® platform and processed using PRINSEQ. The transcriptome assembly was performed using TRINITY assembler. Transcriptome validation was performed by functional characterization with KOG, KEGG, and GO analyses. Additionally, differential expression analysis highlights sex-specific expression patterns, and a list of endocrine and oxidative stress related transcripts are included.

Tissue responsiveness to estradiol and genistein in the sea bass liver and scale

As in mammals, estrogens in fish are essential for reproduction but also important regulators of mineral homeostasis. Fish scales are a non-conventional target tissue responsive to estradiol and constitute a good model to study mineralized tissues effects and mechanisms of action of estrogenic compounds, including phytoestrogens. The responsiveness to estradiol and the phytoestrogen genistein, was compared between the scales and the liver, a classical estrogenic target, in sea bass (Dicentrarchus labrax). Injection with estradiol and genistein significantly increased circulating vitellogenin (for both compounds) and mineral levels (estradiol only) and genistein also significantly increased scale enzymatic activities suggesting it increased mineral turnover. The repertoire, abundance and estrogenic regulation of nuclear estrogen receptors (ESR1, 2a and 2b) and membrane G-protein receptors (GPER and GPER-like) were different between liver and scales, which presumably explains the tissue-specific changes detected in estrogen-responsive gene expression. In scales changes in gene expression mainly consisted of small rapid increases, while in liver strong, sustained increases/decreases in gene expression occurred. Similar but not overlapping gene expression changes were observed in response to both estradiol and genistein. This study demonstrates for the first time the expression of membrane estrogen receptors in scales and that estrogens and phytoestrogens, to which fish may be exposed in the wild or in aquaculture, both affect liver and mineralized tissues in a tissue-specific manner.