In electroreceptive jawed vertebrates, embryonic lateral line placodes give rise to electrosensory ampullary organs as well as mechanosensory neuromasts. Previous reports of shared gene expression suggest that conserved mechanisms underlie electroreceptor and mechanosensory hair cell development and that electroreceptors evolved as a transcriptionally related "sister cell type" to hair cells. We previously identified only one transcription factor gene, Neurod4, as ampullary organ-restricted in the developing lateral line system of a chondrostean ray-finned fish, the Mississippi paddlefish (Polyodon spathula). The other 16 transcription factor genes we previously validated in paddlefish were expressed in both ampullary organs and neuromasts. Here, we used our published lateral line organ-enriched gene-set (arising from differential bulk RNA-seq in late-larval paddlefish), together with a candidate gene approach, to identify 25 transcription factor genes expressed in the developing lateral line system of a more experimentally tractable chondrostean, the sterlet (Acipenser ruthenus, a small sturgeon), and/or that of paddlefish. Thirteen are expressed in both ampullary organs and neuromasts, consistent with conservation of molecular mechanisms. Seven are electrosensory-restricted on the head (Irx5, Irx3, Insm1, Sp5, Satb2, Mafa and Rorc), and five are the first-reported mechanosensory-restricted transcription factor genes (Foxg1, Sox8, Isl1, Hmx2 and Rorb). However, as previously reported, Sox8 is expressed in ampullary organs as well as neuromasts in a catshark (Scyliorhinus canicula), suggesting the existence of lineage-specific differences between cartilaginous and ray-finned fishes. Overall, our results support the hypothesis that ampullary organs and neuromasts develop via largely conserved transcriptional mechanisms, and identify multiple transcription factors potentially involved in the formation of electrosensory versus mechanosensory lateral line organs.
- Publikační typ
- časopisecké články MeSH
Ovarian follicles of sterlets (Acipenser ruthenus) are composed of a single oocyte surrounded by follicular cells (FCs), basal lamina, and thecal cells. Previtellogenic oocytes are polarized. Homogeneous ooplasm (contains ribosomes) and granular ooplasm (comprises nuage aggregations of nuclear origin, rough endoplasmic reticulum (RER), Golgi complexes, ribosomes, and mitochondria) are distinguished. Granular ooplasm is initially located near the nucleus, contacts the plasma membrane of the oocyte (oolemma) and forms a thin layer underneath its entire perimeter. Next, a ring that surrounds the nucleus is formed and sends strands directed toward the oolemma. The lipid body composed of lipid droplets forms adjacent to this ring. Later, the granular ooplasm and strands enlarge toward the oolemma, lipid body disperses, and homogeneous ooplasm is no longer present. A thin cortical ooplasm is formed underneath the oolemma and does not contain any organelles. The oocyte nucleus moves to the center. The nucleoplasm contains lampbrush chromosomes, nuclear bodies, and multiple nucleoli. Early vitellogenic oocytes are polarized, too. Three regions in the ooplasm are distinguished: the perinuclear (contains lipid droplets near the nuclear envelope), the endoplasm (contains yolk platelets and lipid droplets), and the periplasm (contains yolk spheres, pigment granules, and microtubules). In all these regions the RER, Golgi complexes, nuage, and mitochondria are present. Micropinocytotic vesicles, Golgi vesicles and precursors of the internal layer of the egg envelope are in the cortical ooplasm. Some FCs delaminate from the follicular epithelium, degenerate and vesicles are released into the perioocytic space. They may contain precursors of egg envelope and may be involved in "cell-cell" communication. The egg envelope (zona radiata, zona pellucida) is made up of three layers: the vitelline envelope (inner layer), the middle layer, and the outer layer. In its deposition, both the oocyte and FCs are engaged.
- MeSH
- cytoplazma MeSH
- oocyty * MeSH
- ovariální folikul * ultrastruktura MeSH
- ryby MeSH
- vitelogeneze MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The oocyte is a unique cell, from which develops a complex organism comprising of germ layers, tissues and organs. In some vertebrate species it is known that the asymmetrical localization of biomolecules within the oocyte is what drives the spatial differentiation of the daughter cells required for embryogenesis. This asymmetry is first established to produce an animal-vegetal (A-V) axis which reflects the future specification of the ectoderm, mesoderm, and endoderm layers. Several pathways for localization of vegetal maternal transcripts have already been described using a few animal models. However, there is limited information about transcripts that are localized to the animal pole, even though there is accumulating evidence indicating its active establishment. Here, we performed comparative TOMO-Seq analysis on two holoblastic cleavage models: Xenopus laevis and Acipenser ruthenus oocytes during oogenesis. We found that there were many transcripts that have a temporal preference for the establishment of localization. In both models, we observed vegetal transcript gradients that were established during either the early or late oogenesis stages and transcripts that started their localization during the early stages but became more pronounced during the later stages. We found that some animal gradients were already established during the early stages, however the majority were formed during the later stages of oogenesis. Some of these temporally localized transcripts were conserved between the models, while others were species specific. Additionally, temporal de novo transcription and also degradation of transcripts within the oocyte were observed, pointing to an active remodeling of the maternal RNA pool.
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: We tested the toxicity of ethinylestradiol, a semisynthetic estrogen used in oral contraceptives, on all-male triploid zebrafish using commercial feeds and three different doses concentrations. We aimed to determine whether ethinylestradiol peroral administration resulted in vitellogenin production and whether all-male triploid zebrafish could serve as a model species for xenoestrogen testing. METHODS: The actual concentrations of 17α-ethinylestradiol were 0.0035 (low); 0.0315 (medium) and 0.365 (high) μg/g. Positive control represented commercial feeds containing 0.0465 μg/g of β-estradiol. The experiment lasted 8 weeks. RESULTS: Our results indicate that 17α-ethinylestradiol consumption does induce vitellogenin production in triploid zebrafish. CONCLUSIONS: The simple presence of vitellogenin is a definite symptom indicative of the potential for such changes due to the action of estrogenic substances. As such, this experiment has shown that the use of all-male triploid zebrafish populations, rather than the mixed-sex populations of other species previously used, could serve as a suitable alternative model population for controlled testing of the effects of xenoestrogens on fish.
Sturgeons are among the most ancient linages of actinopterygians. At present, many sturgeon species are critically endangered. Surrogate production could be used as an affordable and a time-efficient method for endangered sturgeons. Our study established a method for identifying and isolating type A spermatogonia from different developmental stages of testes using flow cytometric cell sorting (FCM). Flow cytometric analysis of a whole testicular cell suspension showed several well-distinguished cell populations formed according to different values of light scatter parameters. FCM of these different cell populations was performed directly on glass slides for further immunocytochemistry to identify germ cells. Results showed that the cell population in gate P1 on a flow cytometry plot (with high forward scatter and high side scatter parameter values) contains the highest amount of type A spermatogonia. The sorted cell populations were characterized by expression profiles of 10 germ cell specific genes. The result confirmed that setting up for the P1 gate could precisely sort type A spermatogonia in all tested testicular developmental stages. The P2 gate, which was with lower forward scatter and side scatter values mostly, contained type B spermatogonia at a later maturing stage. Moreover, expressions of plzf, dnd, boule, and kitr were significantly higher in type A spermatogonia than in later developed germ cells. In addition, plzf was firstly found as a reliable marker to identify type A spermatogonia, which filled the gap of identification of spermatogonial stem cells in sterlet. It is expected to increase the efficiency of germ stem cell culture and transplantation with plzf identification. Our study thus first addressed a phenotypic characterization of a pure type A spermatogonia population in sterlet. FCM strategy can improve the production of sturgeons with surrogate broodstock and further the analysis of the cellular and molecular mechanisms of sturgeon germ cell development.
- Publikační typ
- časopisecké články MeSH
DNA damage caused by exogenous or endogenous factors is a common challenge for developing fish embryos. DNA damage repair (DDR) pathways help organisms minimize adverse effects of DNA alterations. In terms of DNA repair mechanisms, sturgeons represent a particularly interesting model due to their exceptional genome plasticity. Sterlet (Acipenser ruthenus) is a relatively small species of sturgeon. The goal of this study was to assess the sensitivity of sterlet embryos to model genotoxicants (camptothecin, etoposide, and benzo[a]pyrene), and to assess DDR responses. We assessed the effects of genotoxicants on embryo survival, hatching rate, DNA fragmentation, gene expression, and phosphorylation of H2AX and ATM kinase. Exposure of sterlet embryos to 1 µM benzo[a]pyrene induced low levels of DNA damage accompanied by ATM phosphorylation and xpc gene expression. Conversely, 20 µM etoposide exposure induced DNA damage without activation of known DDR pathways. Effects of 10 nM camptothecin on embryo development were stage-specific, with early stages, before gastrulation, being most sensitive. Overall, this study provides foundational information for future investigation of sterlet DDR pathways.
- MeSH
- benzopyren toxicita MeSH
- embryo nesavčí účinky léků embryologie metabolismus MeSH
- embryonální vývoj účinky léků genetika MeSH
- etoposid toxicita MeSH
- fragmentace DNA účinky léků MeSH
- kamptothecin toxicita MeSH
- kometový test MeSH
- mutageny toxicita MeSH
- oprava DNA * MeSH
- poškození DNA * MeSH
- ryby embryologie genetika MeSH
- testy genotoxicity metody MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Hybrid sterility is a hallmark of speciation, but the underlying molecular mechanisms remain poorly understood. Here, we report that speciation may regularly proceed through a stage at which gene flow is completely interrupted, but hybrid sterility occurs only in male hybrids whereas female hybrids reproduce asexually. We analyzed gametogenic pathways in hybrids between the fish species Cobitis elongatoides and C. taenia, and revealed that male hybrids were sterile owing to extensive asynapsis and crossover reduction among heterospecific chromosomal pairs in their gametes, which was subsequently followed by apoptosis. We found that polyploidization allowed pairing between homologous chromosomes and therefore partially rescued the bivalent formation and crossover rates in triploid hybrid males. However, it was not sufficient to overcome sterility. In contrast, both diploid and triploid hybrid females exhibited premeiotic genome endoreplication, thereby ensuring proper bivalent formation between identical chromosomal copies. This endoreplication ultimately restored female fertility but it simultaneously resulted in the obligate production of clonal gametes, preventing any interspecific gene flow. In conclusion, we demonstrate that the emergence of asexuality can remedy hybrid sterility in a sex-specific manner and contributes to the speciation process.
- MeSH
- biologická evoluce MeSH
- chromozomy MeSH
- hybridní buňky cytologie fyziologie MeSH
- infertilita genetika MeSH
- meióza * MeSH
- partenogeneze * MeSH
- ryby genetika fyziologie MeSH
- vznik druhů (genetika) * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The merit of RNASeq data relies heavily on correct normalization. However, most methods assume that the majority of transcripts show no differential expression between conditions. This assumption may not always be correct, especially when one condition results in overexpression. We present a new method (NormQ) to normalize the RNASeq library size, using the relative proportion observed from RT-qPCR of selected marker genes. The method was compared against the popular median-of-ratios method, using simulated and real-datasets. NormQ produced more matches to differentially expressed genes in the simulated dataset and more distribution profile matches for both simulated and real datasets.
- Publikační typ
- časopisecké články MeSH
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
- Publikační typ
- tisková chyba MeSH
Fatty acid desaturase 2 (Fads2) is the key enzyme of long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis. Endogenous production of these biomolecules in vertebrates, if present, is insufficient to meet demand. Hence, LC-PUFA are considered as conditionally essential. At present, however, LC-PUFA are globally limited nutrients due to anthropogenic factors. Research attention has therefore been paid to finding ways to maximize endogenous LC-PUFA production, especially in production species, whereby deeper knowledge on molecular mechanisms of enzymatic steps involved is being generated. This review first briefly informs about the milestones in the history of LC-PUFA essentiality exploration before it focuses on the main aim-to highlight the fascinating Fads2 potential to play roles fundamental to adaptation to novel environmental conditions. Investigations are summarized to elucidate on the evolutionary history of fish Fads2, providing an explanation for the remarkable plasticity of this enzyme in fish. Furthermore, structural implications of Fads2 substrate specificity are discussed and some relevant studies performed on organisms other than fish are mentioned in cases when such studies have to date not been conducted on fish models. The importance of Fads2 in the context of growing aquaculture demand and dwindling LC-PUFA supply is depicted and a few remedies in the form of genetic engineering to improve endogenous production of these biomolecules are outlined.
- MeSH
- desaturasy mastných kyselin chemie metabolismus MeSH
- fylogeneze MeSH
- genetické inženýrství MeSH
- nenasycené mastné kyseliny chemie MeSH
- regulace genové exprese MeSH
- rybí proteiny chemie metabolismus MeSH
- ryby * MeSH
- substrátová specifita MeSH
- transgeny MeSH
- vodní hospodářství MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zánět MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
