Background: The hormonal control of oocyte maturation and ovulation as well as the molecular mechanisms of nuclear maturation have been thoroughly studied in fish. In contrast, the other molecular events occurring in the ovary during post-vitellogenesis have received far less attention.

In this study UiO-66 and UiO-66-NH 2 were synthesized by solvothermal method. The effect of preparation conditions on the quality of UiO-66-NH 2 was studied. The obtained material has been characterized by x-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimatric analysis (TGA), scanning electron microscopy (SEM) and nitrogen physisorption measurements (BET). The CO 2 and CH 4 physisorption measurements were carried out using a high pressure volumetric analyzer (Micromeritics HPVA-100). The results showed that the UiO-66-NH 2 of ball shape crystalline had been obtained and characterized by high surface area (BET) up to 876 m 2 g −1 , specific volume 0.379 cm 3 g −1 , pore radius 9.5 Å and thermal stability up to 673 K, respectively. The experiments indicated that in comparison with UiO-66 the addition of NH 2 is able to increase the CO 2 and CH 4 storage capacity at 1 bar and 303 K twice from 28.43 cm 3 g −1 up to 52 cm 3 g −1 and from 6.68 cm 3 g −1 to 11.1 cm 3 g −1 , respectively.

A cDNA encoding for a novel rainbow trout SHBG was identified and characterized. Phylogenetic analysis showed that this novel SHBG, named SHBGb, was a highly divergent paralog of the classical SHBG (SHBGa) form previously known in vertebrates including zebrafish, seabass, and rainbow trout. Using all available sequences, no SHBGb-like sequence could be identified in any fish species besides Atlantic salmon. Rainbow trout SHBGa and SHBGb share only 26% sequence identity at the amino acid level and exhibit totally distinct tissue distribution, thus demonstrating a functional shift of SHBGb. Indeed, shbga mRNA was predominantly expressed in liver and spleen but could not be detected in the ovary, whereas shbgb had a predominant ovarian expression but could not be detected in liver. Despite its high divergence, rainbow trout SHBGb expressed in COS-7 cells could bind estradiol and testosterone with high affinity and specificity. Both rainbow trout shbgb mRNA and proteins were localized to the granulosa cells of vitellogenic ovarian follicles, whereas SHBGb immunoreactivity was also found in theca cells. Finally, shbgb ovarian mRNA expression exhibited a significant drop between late vitellogenesis and oocyte maturation at a time when ovarian aromatase (cyp19a) gene expression and estradiol circulating levels exhibited a dramatic decrease. Together, these observations show that SHBGb is a functional and highly divergent SHBG paralog probably arising from a salmonid-specific duplication of the shbg gene.

A real-time polymerase chain reaction-based gene expression survey was performed using 37 target genes and 22 female rainbow trout sampled during follicular maturational competence (FMC) acquisition or during oocyte maturation. In females sampled before meiosis resumption, FMC was estimated using an in vitro assay. Several growth factors, bone morphogenetic proteins, steroidogenic enzymes, cathepsins, genes known to play a role in the fish preovulatory ovary, as well as previously unstudied genes, were analyzed in this survey. Gene expression profiling was performed using a supervised clustering analysis in order to identify groups of genes exhibiting similar expression profiles in the ovary during FMC acquisition and follicular maturation. From the clustering analysis, three clusters exhibiting a specific expression during FMC acquisition or at the time of oocyte maturation were identified. Cluster 1 was characterized by a progressive increase in gene expression during FMC acquisition, whereas cluster 2 exhibited an increased expression at the time of oocyte maturation. In contrast, cluster 3 was characterized by a decreased mRNA expression at the time of oocyte maturation. Among the 37 target genes used in this survey, 18 were significantly regulated during maturational competence acquisition or at the time of oocyte maturation. Among these 18 genes, 16 belonged to one of the three clusters identified. Although the results allowed a global description of gene expression profiles, they also suggest an important role for several factors, including some previously unstudied bone morphogenetic proteins, in the paracrine control of FMC acquisition and meiosis resumption.

BackgroundDespite the known importance of somatic cells for oocyte developmental competence acquisition, the overall mechanisms underlying the acquisition of full developmental competence are far from being understood, especially in non-mammalian species. The present work aimed at identifying key molecular signals from somatic origin that would be shared by vertebrates.ResultsUsing a parallel transcriptomic analysis in 4 vertebrate species - a teleost fish, an amphibian, and two mammals - at similar key steps of developmental competence acquisition, we identified a large number of species-specific differentially expressed genes and a surprisingly high number of orthologous genes exhibiting similar expression profiles in the 3 tetrapods and in the 4 vertebrates. Among the evolutionary conserved players participating in developmental competence acquisition are genes involved in key processes such as cellular energy metabolism, cell-to-cell communications, and meiosis control. In addition, we report many novel molecular actors from somatic origin that have never been studied in the vertebrate ovary. Interestingly, a significant number of these new players actively participate in Drosophila oogenesis.ConclusionsOur study provides a comprehensive overview of evolutionary-conserved mechanisms from somatic origin participating in oocyte developmental competence acquisition in 4 vertebrates. Together our results indicate that despite major differences in ovarian follicular structure, some of the key players from somatic origin involved in oocyte developmental competence acquisition would be shared, not only by vertebrates, but also by metazoans. The conservation of these mechanisms during vertebrate evolution further emphasizes the important contribution of the somatic compartment to oocyte quality and paves the way for future investigations aiming at better understanding what makes a good egg.

Fish are sensitive to temperature, but the intergenerational consequences of maternal exposure to high temperature on offspring behavioural plasticity and underlying mechanisms are unknown. Here we show that a thermal maternal stress induces impaired emotional and cognitive responses in offspring rainbow trout (Oncorhynchus mykiss). Thermal stress in mothers triggered the inhibition of locomotor fear-related responses upon exposure to a novel environment and decreased spatial learning abilities in progeny. Impaired behavioural phenotypes were associated with the dysregulation of several genes known to play major roles in neurodevelopment, including auts2 (autism susceptibility candidate 2), a key gene for neurodevelopment, more specifically neuronal migration and neurite extension, and critical for the acquisition of neurocognitive function. In addition, our analysis revealed the dysregulation of another neurodevelopment gene (dpysl5) as well as genes associated with human cognitive disorders (arv1, plp2). We observed major differences in maternal mRNA abundance in the eggs following maternal exposure to high temperature indicating that some of the observed intergenerational effects are mediated by maternally-inherited mRNAs accumulated in the egg. Together, our observations shed new light on the intergenerational determinism of fish behaviour and associated underlying mechanisms. They also stress the importance of maternal history on fish behavioural plasticity.

Scrutiny of the zebrafish (Danio rerio) genomic database confirmed eight functional vitellogenin (vtg) genes, each with one or two transcript variants, and the encoded Vtg polypeptides were structurally and functionally characterized in detail by in silico and experimental analyses. There were five type I (vtgs1, 4, 5, 6, and 7), two type II (vtg2 and vtg8), and one type III (vtg3) vtg gene(s) encoding three major types of Vtg protein based on subdomain structure (Vtg-I, Vtg-II, and Vtg-III, respectively). Among various tissues of mature zebrafish, transcripts of the eight vtg genes were detected by RNA-Seq only in liver and intestine, with liver being the main site of vtg expression. All vtg transcripts except vtg8 were also detected in mature female liver by RT-qPCR. The relative abundances of Vtg proteins and their variants were quantified by LC-MS/MS in the liver of mature females and in eggs. The Vtgs were generally several fold more abundant in eggs, but profiles of abundance of the 19 different forms of Vtg evaluated were otherwise similar in liver and eggs, suggesting that yolk protein composition is determined largely by hepatic Vtg synthesis and secretion. Based on transcript and protein levels, Vtg-I is, by far, the dominant type of Vtg in zebrafish, followed by Vtg-II and then Vtg-III. When relative abundances of the different forms of Vtg were evaluated by LC-MS/MS in egg batches of good versus poor quality, no differences in the proportional abundance of individual forms of Vtg, or of different Vtg types, attributable to egg quality were observed.

A series of Ni/SBA-15 catalysts was prepared by impregnation method. Effect of NiO content (3060 mass%), calcination time (0.52 h at 800°C), and reduction time (12 h at 800°C) on catalytic performance in combined steam and CO 2 reforming of CH 4 (CSCRM) was studied. N 2 physisorption measurements, powder X-ray diffraction, Hydrogen temperature-programmed reduction, CO 2-temperature-programmed desorption, and transmission electron microscopy were used to investigate physico-chemical properties of the catalysts. The catalytic performance of Ni/SBA-15 in CSCRM was assessed in the temperature range of 550800°C. The results revealed suitable time for calcination and reduction being 0.5 h and 1.5 h, respectively. After these treatments, 40 mass% NiO/SBA-15 catalyst was more active and exhibited higher activity than others. At 750°C, conversion of CH 4 and CO 2 on this catalyst in CSCRM was 91.05% and 78.11%, respectively. High surface area, better reducibility, and good affinity with CO 2 contribute to the high performance of this catalyst.