BPA-Induced Deregulation of Epigenetic Patterns: Effects on Female Zebrafish Reproduction

Bisphenol A (BPA) is one of the commonest Endocrine Disruptor Compounds worldwide. It interferes with vertebrate reproduction, possibly by inducing deregulation of epigenetic mechanisms. To determine its effects on female reproductive physiology and investigate whether changes in the expression levels of genes related to reproduction are caused by histone modifications, BPA concentrations consistent with environmental exposure were administered to zebrafish for three weeks. Effects on oocyte growth and maturation, autophagy and apoptosis processes, histone modifications, and DNA methylation were assessed by Real-Time PCR (qPCR), histology, and chromatin immunoprecipitation combined with qPCR analysis (ChIP-qPCR). The results showed that 5 μg/L BPA down-regulated oocyte maturation-promoting signals, likely through changes in the chromatin structure mediated by histone modifications, and promoted apoptosis in mature follicles. These data indicate that the negative effects of BPA on the female reproductive system may be due to its upstream ability to deregulate epigenetic mechanism

Beneficial bacteria affect Danio rerio development by the modulation of maternal factors involved in autophagic, apoptotic and dorsalizing processes.

Background/Aims: Probiotic strains have been recognized to exert important roles in many biological systems, including immune response, growth, development and reproduction. However, to date, no studies have focused either on the relation among probiotics and maternal factors or on probiotics' ability to qualitatively and/or quantitatively modulate maternal transcripts. Methods: In this study, the effects of Lactobacillusrhamnosus administered to parental fish on the control of maternal factors involved in autophagic, apoptotic and dorsalizing processes during zebrafish embryo development were assessed through q-PCRs, WMISH and TUNEL assay. Results: The results we obtained show that probiotic induced significant changes in both maternal and zygotic mRNA levels involved in embryo development. The maternal autophagy-regulating genes herein investigated -ambra1a, ambra1b, beclin, lc3-, as well as those involved in the apoptotic process -caspase3, bcl2, bax- were modulated in disfavor and favor of the treated group, respectively. Also, the key transcripts ruling the dorsalizing process -goosecoid and chordin- were subject to a significant regulation of their gene expression. Conclusion: The results we acquired demonstrated that parentally administered Lactobacillusrhamnosus is able to modulate important physiological processes involved in zebrafish embryo development

DEHP Impairs Zebrafish Reproduction by Affecting Critical Factors in Oogenesis

Public concerns on phthalates distributions in the environment have been increasing since they can cause liver cancer, structural abnormalities and reduce sperm counts in male reproductive system. However, few data are actually available on the effects of Di-(2-ethylhexyl)-phthalate (DEHP) in female reproductive system. The aim of this study was to assess the impacts of DEHP on zebrafish oogenesis and embryo production. Female Danio rerio were exposed to environmentally relevant doses of DEHP and a significant decrease in ovulation and embryo production was observed. The effects of DEHP on several key regulators of oocyte maturation and ovulation including bone morphogenetic protein-15 (BMP15), luteinizing hormone receptor (LHR), membrane progesterone receptors (mPRs) and cyclooxygenase (COX)-2 (ptgs2) were determined by real time PCR. The expressions of BMP15 and mPR proteins were further determined by Western analyses to strengthen molecular findings. Moreover, plasma vitellogenin (vtg) titers were assayed by an ELISA procedure to determine the estrogenic effects of DEHP and its effects on oocyte growth. A significant reduction of fecundity in fish exposed to DEHP was observed. The reduced reproductive capacity was associated with an increase in ovarian BMP15 levels. This rise, in turn, was concomitant with a significant reduction in LHR and mPRβ levels. Finally, ptgs2 expression, the final trigger of ovulation, was also decreased by DEHP. By an in vitro maturation assay, the inhibitory effect of DEHP on germinal vesicle breakdown was further confirmed. In conclusion, DEHP affecting signals involved in oocyte growth (vtg), maturation (BMP15, LHR, mPRs,) and ovulation (ptgs2), deeply impairs ovarian functions with serious consequences on embryo production. Since there is a significant genetic similarity between D.rerio and humans, the harmful effects observed at oocyte level may be relevant for further molecular studies on humans

Zebrafish as a Model to Unveil the Pro-Osteogenic Effects of Boron-Vitamin D3 Synergism

The micronutrient boron (B) plays a key role during the ossification process as suggested by various in vitro and in vivo studies. To deepen our understanding of the molecular mechanism involved in the osteogenicity of B and its possible interaction with vitamin D3 (VD), wild-type AB zebrafish (Danio rerio) were used for morphometric analysis and transcriptomic analysis in addition to taking advantage of the availability of specific zebrafish osteoblast reporter lines. First, osteoactive concentrations of B, VD, and their combinations were established by morphometric analysis of the opercular bone in alizarin red-stained zebrafish larvae exposed to two selected concentrations of B (10 and 100 ng/ml), one concentration of VD (10 pg/ml), and their respective combinations. Bone formation, as measured by opercular bone growth, was significantly increased in the two combination treatments than VD alone. Subsequently, a transcriptomic approach was adopted to unveil the molecular key regulators involved in the synergy. Clustering of differentially expressed genes revealed enrichment toward bone and skeletal functions in the groups co-treated with B and VD. Downstream analysis confirmed mitogen-activated protein kinase as the most regulated pathway by the synergy groups in addition to transforming growth factor-beta signaling, focal adhesion, and calcium signaling. The best-performing synergistic treatment, B at 10 ng/ml and VD at 10 pg/ml, was applied to two zebrafish transgenic lines, Tg(sp7:mCherry) and Tg(bglap:EGFP), at multiple time points to further explore the results of the transcriptomic analysis. The synergistic treatment with B and VD induced enrichment of intermediate (sp7(+)) osteoblast at 6 and 9 days post fertilization (dpf) and of mature (bglap(+)) osteoblasts at 15 dpf. The results obtained validate the role of B in VD-dependent control over bone mineralization and can help to widen the spectrum of therapeutic approaches to alleviate pathological conditions caused by VD deficiency by using low concentrations of B as a nutritional additive.info:eu-repo/semantics/publishedVersio

Knockout of the Glucocorticoid Receptor Impairs Reproduction in Female Zebrafish

none8The pleiotropic effects of glucocorticoids in metabolic, developmental, immune and stress response processes have been extensively investigated; conversely, their roles in reproduction are still less documented. It is well known that stress or long-lasting therapies can cause a strong increase in these hormones, negatively affecting reproduction. Moreover, the need of glucocorticoid (GC) homeostatic levels is highlighted by the reduced fertility reported in the zebrafish glucocorticoid receptor mutant (nr3c1ia30/ia30) line (hereafter named gr-/-). Starting from such evidence, in this study, we have investigated the role of glucocorticoid receptor (Gr) in the reproduction of female zebrafish. Key signals orchestrating the reproductive process at the brain, liver, and ovarian levels were analyzed using a multidisciplinary approach. An impairment of the kiss-GnRH system was observed at the central level in (gr-/-) mutants as compared to wild-type (wt) females while, in the liver, vitellogenin (vtg) mRNA transcription was not affected. Changes were instead observed in the ovary, particularly in maturing and fully grown follicles (classes III and IV), as documented by the mRNA levels of signals involved in oocyte maturation and ovulation. Follicles isolated from gr-/- females displayed a decreased level of signals involved in the acquisition of competence and maturation, causing a reduction in ovulation with respect to wt females. Fourier transform infrared imaging (FTIRI) analysis of gr-/- follicle cytoplasm showed major changes in macromolecule abundance and distribution with a clear alteration of oocyte composition. Finally, differences in the molecular structure of the zona radiata layer of gr-/- follicles are likely to contribute to the reduced fertilization rate observed in mutants.openMaradonna, Francesca; Gioacchini, Giorgia; Notarstefano, Valentina; Fontana, Camilla Maria; Citton, Filippo; Dalla Valle, Luisa; Giorgini, Elisabetta; Carnevali, OlianaMaradonna, Francesca; Gioacchini, Giorgia; Notarstefano, Valentina; Fontana, Camilla Maria; Citton, Filippo; Dalla Valle, Luisa; Giorgini, Elisabetta; Carnevali, Olian

Sustainable Ornamental Fish Aquaculture: The Implication of Microbial Feed Additives

Ornamental fish trade represents an important economic sector with an export turnover that reached approximately 5 billion US dollars in 2018. Despite its high economic importance, this sector does not receive much attention. Ornamental fish husbandry still faces many challenges and losses caused by transport stress and handling and outbreak of diseases are still to be improved. This review will provide insights on ornamental fish diseases along with the measures used to avoid or limit their onset. Moreover, this review will discuss the role of different natural and sustainable microbial feed additives, particularly probiotics, prebiotics, and synbiotics on the health, reduction in transport stress, growth, and reproduction of farmed ornamental fish. Most importantly, this review aims to fill the informational gaps existing in advanced and sustainable practices in the ornamental fish production

Growth and stress factors in ballan wrasse (Labrus bergylta) larval development

Ballan wrasse (Labrus bergylta) is a specialized cleaner fish used in salmon farms as a biological treatment against sea lice. Its commercial rearing is at present mostly experimental. A number of key aspects, including the molecular and physiological mechanisms that promote its growth and development, are still largely unexplored. In this study histological, biometric, biochemical and molecular approaches are combined for the first time to investigate the changes in growth (insulin-like growth factor 1 and 2 and myostatin) and stress (heat shock protein 70 and cortisol) markers that occur during ballan wrasse larval development by relating them to larval stages and feed changes. The real-time PCR data demonstrated that igf1 transcripts rose from 1 day post-hatching (dph) and were no longer detectable 38 dph, whereas igf2 and myostatin transcripts were low and stable until 28 dph, then rose in late larval stages. The biometric and histological data matched the molecular findings, documenting rapid growth and development of the larval digestive tract and assimilation ability. Cortisol was lowest at hatching, it rose slightly at first feeding, and then increased during larval development; a similar trend was detected for hsp70 gene expression. The low cortisol levels found at the earliest larval stages reflect a poor stress-coping ability, a feature that may actually protect larvae from the elevated metabolic demands involved by stress responses and promote faster growth and survival. The present data can be applied to improve the rearing performances of this important cleaner species and reduce captures from the wild

Melatonin Induces Follicle Maturation in Danio rerio

Most organisms modulate their reproductive activity responding to day length by the nocturnal release of melatonin by the pineal gland. This hormone is also responsible for synchronizing reproduction with specific external environment stimuli in order to optimize reproductive success