scholarly journals Developmental exposure window influences silver toxicity but does not affect the susceptibility to subsequent exposures in zebrafish embryos

2020 ◽  
Vol 154 (5) ◽  
pp. 579-595
Author(s):  
Paige C. Robinson ◽  
Hannah R. Littler ◽  
Anke Lange ◽  
Eduarda M. Santos
Keyword(s):  
Early Development ◽  
Toxic Metal ◽  
Positive Control ◽  
Zebrafish Embryos ◽  
Chemical Toxicity ◽  
Experimental Conditions ◽  
Cell Stage ◽  
Developmental Exposure ◽  
Methylation Inhibitor ◽  
The One

AbstractSilver is a non-essential, toxic metal widespread in freshwaters and capable of causing adverse effects to wildlife. Its toxic effects have been studied in detail but less is known about how sensitivity varies during development and whether pre-exposures affect tolerance upon re-exposure. We address these knowledge gaps using the zebrafish embryo (Danio rerio) model to investigate whether exposures encompassing stages of development prior to mid-blastula transition, when chorion hardening and epigenetic reprogramming occur, result in greater toxicity compared to those initiated after this period. We conducted exposures to silver initiated at 0.5 h post fertilisation (hpf) and 4 hpf to determine if toxicity differed. In parallel, we exposed embryos to the methylation inhibitor 5-azacytidine as a positive control. Toxicity increased when exposures started from 0.5 hpf compared to 4 hpf and LC50 were significantly lower by 1.2 and 7.6 times for silver and 5-azacyitidine, respectively. We then investigated whether pre-exposure to silver during early development (from 0.5 or 4 hpf) affected the outcome of subsequent exposures during the larvae stage, and found no alterations in toxicity compared to naïve larvae. Together, these data demonstrate that during early development zebrafish embryos are more sensitive to silver when experiments are initiated at the one-cell stage, but that pre-exposures do not influence the outcome of subsequent exposures, suggesting that no long-lasting memory capable of influencing future susceptibility was maintained under our experimental conditions. The finding that toxicity is greater for exposures initiated at the one-cell stage has implications for designing testing systems to assess chemical toxicity.

The utilization of an inhibitor of spermidine and spermine synthesis as a tool for the study of the determination of cavitation in the preimplantation mouse embryo

Development ◽  
1979 ◽  
Vol 53 (1) ◽  
pp. 145-162
Author(s):  
H. Alexandre
Keyword(s):  
Biological Clock ◽  
Duration Of Treatment ◽  
Experimental Conditions ◽  
Cell Stage ◽  
Cytoplasmic Factor ◽  
Average Cell ◽  
Length Of Treatment ◽  
Preimplantation Mouse ◽  
The One

The inhibition of spermidine and spermine synthesis by methylglyoxal-Bis(guanylhydrazone) (MeGAG) at concentrations of 5, 10 and 20 µM, induces a reversible metabolic quiescence of mouse embryos, cultured in vitro from the 2-cell stage, at an average of 10·2, 8·5 and 6·9 cell stages respectively. In contrast, the inhibition of putrescine synthesis by α-methylornithine (α-MeOrn) at concentrations up to 10 mM fails to inhibit blastocyst formation, as shown previously. Complete reversibility of this induced arrest of development is observed for treatments up to 31 h with MeGAG at 10 µM. In agreement with the biological clock theory of Smith & MacLaren's hypothesis, the delay in cavitation is proportional to the length of treatment. However, the average cell numbers of the ‘delayed nascent blastocysts’ of all treated embryos (21·8–24·2) are consistently lower than that of control embryos (33·6) irrespective of the duration of treatment. It seems therefore that under some experimental conditions, DNA and chromosome replication on the one hand and cytoplasmic maturation on the other may be desynchronized. This suggests a role for a cytoplasmic factor in the induction of cavitation.

scholarly journals Mutant MAPK7-Induced Idiopathic Scoliosis is Linked to Impaired Osteogenesis

2018 ◽  
Vol 48 (3) ◽  
pp. 880-890 ◽  
Author(s):  
Taifeng Zhou ◽  
Chong Chen ◽  
Caixia Xu ◽  
Hang Zhou ◽  
Bo Gao ◽  
...  
Keyword(s):  
Idiopathic Scoliosis ◽  
Western Blotting ◽  
Messenger Rna ◽  
Human Mesenchymal Stem Cells ◽  
Control Group ◽  
Zebrafish Embryos ◽  
Small Interfering Rnas ◽  
Cell Stage ◽  
Alizarin Red ◽  
The One

Background/Aims: Three rare MAPK7 variants that predispose individuals to adolescent idiopathic scoliosis have previously been identified. However, the mechanism underlying the effects of the mutations remain unknown. Methods: Human mesenchymal stem cells (hMSCs) were isolated from both patients and healthy volunteer donors, and MAPK7 expression was detected by western blotting and real-time quantitative PCR (RT-qPCR). Zebrafish embryos were injected with mapk7 morpholinos or co-injected with morpholinos and wild-type (WT) MAPK7 messenger RNA (mRNA) at the one-cell stage, followed by calcein staining to evaluate bone formation. hMSCs were transfected with MAPK7 small interfering RNAs and osteogenesis was induced for 14 days. Alizarin red staining was performed and osteoblast markers were detected by western blotting and RT-qPCR. Since RPS6KA3 is a downstream target of MAPK7 and plays an important role in the osteogenesis, zebrafish embryos were then injected with rps6ka3 morpholinos, or co-injected with rps6ka3 or mapk7 morpholinos and WT RPS6KA3 mRNA at the one-cell stage. Results: MAPK7 expression in the patient group was much lower than in the control group. Morpholino-induced mapk7 knockdown in zebrafish embryos led to body curvature, which was significantly reversed by WT MAPK7 mRNA. Calcein staining revealed that mapk7-knockdown delayed the ossification of the vertebrae. MAPK7 silencing in hMSCs impaired osteogenesis and downregulated osteoblast marker expression. Morpholino-induced rps6ka3-knockdown in zebrafish embryos led to body curvature, which was reversed by WT RPS6KA3 mRNA. Interestingly, RPS6KA3 mRNA also partially reversed the phenotype induced by mapk7 morpholinos. Conclusion: Impaired osteogenesis is linked to mutant MAPK7-induced idiopathic scoliosis , and RPS6KA3 may play an important role in this process.

scholarly journals Direct Visualization of Live Zebrafish Glycan via Single-step Metabolic Labeling with Fluorophore-tagged Nucleotide Sugars

2019 ◽  
Author(s):  
Senlian Hong ◽  
Pankaj Sahai-Hernandez ◽  
David Traver ◽  
Peng Wu
Keyword(s):  
Developmental Stages ◽  
Single Step ◽  
Zebrafish Embryos ◽  
Metabolic Labeling ◽  
Cell Stage ◽  
Imaging Probes ◽  
Nucleotide Sugars ◽  
Living Organisms ◽  
The One

ABSTRACTDynamic turnover of cell-surface glycans is involved in a myriad of biological events, making this process an attractive target for in vivo molecular imaging. The metabolic glycan labeling coupled with ‘bioorthogonal chemistry’ has paved the way for visulizing glycans in living organisms. However, a two-step labeling sequence is required, which is prone to tissue penetration difficulties of the imaging probes. Here, by exploring the substrate promiscuity of endogenous glycosyltransferases, we developed a single-step fluorescent glycan labeling strategy by using fluorophore-tagged analogs of nucleotide sugars directly. Injecting the fluorophore-tagged sialic acid and fucose into the yolk of zebrafish embryos at the one-cell stage enables a systematic imaging of sialylation and fucosylation in live zebrafish embryos at various developmental stages. From these studies, we obtained insights into the role of sialylated and fucosylated glycans in zebrafish hematopoiesis.

THE RELATION BETWEEN THE HYPOTHALAMIC NEUROSECRETION AND THE CORTICOTROPHIN RELEASE IN EXPERIMENTAL CONDITIONS

1960 ◽  
Vol XXXIV (I) ◽  
pp. 8-18 ◽  
Author(s):  
E. Kivalo ◽  
U. K. Rinne
Keyword(s):  
Paraventricular Nucleus ◽  
Median Eminence ◽  
Supraoptic Nucleus ◽  
Acute Stress ◽  
Neurosecretory Material ◽  
Experimental Conditions ◽  
Hypothalamic Cells ◽  
The One ◽  
Hypophysial Portal ◽  
Acth Release

ABSTRACT Acute stress, chronic stress plus hydration, cortisone treatment, cortisone treatment plus dehydration were used as methods of investigation and the relation between the neurosecretory activity of the hypothalamic supraoptic nucleus and paraventricular nucleus and the neurosecretory material around the hypophysial portal vessels of the median eminence on the one hand and the corticotrophin release on the other hand, has been studied in the rat. Whereas stress stimulates both the activity of the above mentioned cells of the hypothalamus and the ACTH release, stress plus hydration causes a depression of these hypothalamic cells but nevertheless causes a marked ACTH release. Cortisone inhibits the activity of the cells in the supraoptic nucleus and the paraventricular nucleus as well as the ACTH release whereas cortisone plus dehydration causes stimulation but inhibits the ACTH release. In some stress and cortisone treatment groups the variations of the neurosecretory material around the hypophysial portal vessels and of the ACTH release were found to show a correlation. It is concluded that the activity of the cells of the supraoptic nucleus and the paraventricular nucleus and the ACTH release do not seem to have any definite connection, whereas some observations indicate that the neurosecretory material in the region of the median eminence around the hypophysial portal vessels may have some significance in ACTH release.

scholarly journals Alpha EEG Frontal Asymmetries during Audiovisual Perception in Cochlear Implant Users

2015 ◽  
Vol 54 (06) ◽  
pp. 500-504 ◽  
Author(s):  
A. G. Maglione ◽  
A. Scorpecci ◽  
P. Malerba ◽  
P. Marsella ◽  
S. Giannantonio ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Alpha Rhythm ◽  
Normal Hearing ◽  
Experimental Conditions ◽  
Audiovisual Perception ◽  
Audiovisual Stimuli ◽  
The Difference ◽  
Eeg Alpha ◽  
The One ◽  
Hearing Children

SummaryObjectives: The aim of the present study is to investigate the variations of the electroencephalographic (EEG) alpha rhythm in order to measure the appreciation of bilateral and unilateral young cochlear implant users during the observation of a musical cartoon. The cartoon has been modified for the generation of three experimental conditions: one with the original audio, another one with a distorted sound and, finally, a mute version.Methods: The EEG data have been recorded during the observation of the cartoons in the three experimental conditions. The frontal alpha EEG imbalance has been calculated as a measure of motivation and pleasantness to be compared across experimental populations and conditions.Results: The EEG frontal imbalance of the alpha rhythm showed significant variations during the perception of the different cartoons. In particular, the pattern of activation of normal-hearing children is very similar to the one elicited by the bilateral implanted patients. On the other hand, results related to the unilateral subjects do not present significant variations of the imbalance index across the three cartoons.Conclusion: The presented results suggest that the unilateral patients could not appreciate the difference in the audio format as well as bilaterally implanted and normal hearing subjects. The frontal alpha EEG imbalance is a useful tool to detect the differences in the appreciation of audiovisual stimuli in cochlear implant patients.

scholarly journals Effects of embryo culture on global pattern of gene expression in preimplantation mouse embryos

Reproduction ◽  
2004 ◽  
Vol 128 (3) ◽  
pp. 301-311 ◽  
Author(s):  
Paolo Rinaudo ◽  
Richard M Schultz
Keyword(s):  
Gene Expression ◽  
Preimplantation Embryos ◽  
Expression Analysis Systematic Explorer ◽  
Cell Stage ◽  
Global Pattern ◽  
Preimplantation Mouse Embryos ◽  
Preimplantation Mouse ◽  
Global Patterns ◽  
The One

Culture of preimplantation embryos affects gene expression. The magnitude of the effect on the global pattern of gene expression, however, is not known. We compared global patterns of gene expression in blastocysts cultured from the one-cell stage in either Whitten’s medium or KSOM + amino acids (KSOM/AA) with that of blastocysts that developed in vivo, using the Affymetrix MOE430A chip. The analysis revealed that expression of 114 genes was affected after culture in Whitten’s medium, whereas only 29 genes were mis-expressed after culture in KSOM/AA. Expression Analysis Systematic Explorer was used to identify biological and molecular processes that are perturbed after culture and indicated that genes involved in protein synthesis, cell proliferation and transporter function were down-regulated after culture in Whitten’s medium. A common set of genes involved in transporter function was also down-regulated after culture in KSOM/AA. These results provide insights as to why embryos develop better in KSOM/AA than in Whitten’s medium, and highlight the power of microarray analysis to assess global patterns of gene expression.

The early development of haploid and aneuploid parthenogenetic embryos

Development ◽  
1975 ◽  
Vol 34 (3) ◽  
pp. 645-655
Author(s):  
Matthew H. Kaufman ◽  
Leo Sachs
Keyword(s):  
Early Development ◽  
Polar Body ◽  
Chromosome Counts ◽  
Cell Stage ◽  
Haploid Chromosome Number ◽  
Stage Of Development ◽  
Morula Stage ◽  
Second Polar Body ◽  
Similar Development ◽  
Parthenogenetic Embryos

The early development of parthenogenetically activated oocytes has been studied in C57BL × CBA-T6T6 (F1T6) translocation heterozygote mice and C57BL × CBA-LAC (F1LAC) mice. All F1T6 oocytes had either a quadrivalent or a univalent-trivalent configuration at meiosis I; no such chromosome configurations were observed in the F1LAC oocytes. At ovulation 36·5 % of the F1T6 oocytes had 19 or 21 chromosomes, whereas 97 % of the F1LAC had the normal haploid chromosome number of 20. After parthenogenetic activation, chromosome counts at metaphase of the first cleavage mitosis were made of the eggs with a single pronucleus following extrusion of the second polar body. These activated eggs had similar frequencies of 19, 20 and 21 chromosomes as had the oocytes at ovulation. The activated 1-cell eggs were transferred to the oviducts of pseudopregnant recipients and the embryos recovered 3 days later. At this stage of development, most of the F1T6 embryos with 19 chromosomes were no longer found, but the frequency of 21-chromosome embryos was similar to the frequency of 21-chromosome oocytes and activated eggs. There was a similar mean number of cells in the embryos with 20 and 21 chromosomes. The results indicate that nearly all the embryos with 19 chromosomes failed to develop, probably beyond the 2-cell stage, whereas oocytes with 21 chromosomes had a similar development to oocytes with 20 chromosomes up to the morula stage.

Synthesis and phosphorylation of uvomorulin during mouse early development

Development ◽  
1992 ◽  
Vol 115 (1) ◽  
pp. 313-318 ◽  
Author(s):  
M. Sefton ◽  
M.H. Johnson ◽  
L. Clayton
Keyword(s):  
Cell Adhesion ◽  
Early Development ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Blastocyst Stage ◽  
Embryonic Stage ◽  
Cell Stage ◽  
Mouse Oocytes ◽  
Maternal Mrna ◽  
Embryonic Genome

The cell adhesion molecule, uvomorulin, is synthesised in both the 135 × 10(3) M(r) precursor and 120 × 10(3) M(r) mature forms on maternal mRNA templates in unfertilized and newly fertilized mouse oocytes. Synthesis on maternal message ceases during the 2-cell stage to resume later on mRNA encoded presumptively by the embryonic genome. Uvomorulin is detectable by immunoblotting at all stages upto the blastocyst stage, but shows variations in its total amount and processing with embryonic stage. Whilst only trace levels of phosphorylated uvomorulin are detectable in early and late 4-cell embryos, uvomorulin in 8-cell embryos is phosphorylated.

scholarly journals MALARIAL PIGMENT (HEMATIN) AS A FACTOR IN THE PRODUCTION OF THE MALARIAL PAROXYSM

1912 ◽  
Vol 15 (6) ◽  
pp. 579-597 ◽  
Author(s):  
Wade H. Brown
Keyword(s):  
Human Subject ◽  
Toxic Substance ◽  
Malarial Parasite ◽  
Striking Similarity ◽  
Conservative Estimate ◽  
Experimental Conditions ◽  
Malarial Infection ◽  
Sequence Of Events ◽  
Abundant Evidence ◽  
The One

The paroxysm of hematin intoxication in the rabbit undoubtedly presents many features of striking similarity to the paroxysm of human malaria; still one must hesitate to apply such results unreservedly in an attempt to identify the causative agent of the malarial paroxysm. When, in addition to the character of the paroxysm, we consider the sequence of events in the two instances, the analogy becomes so close that it seems impossible to regard the matter as a mere coincidence. The injection of hematin, especially in fractional doses, is in a measure comparable to the liberation of hematin into the human circulation by the malarial parasite. In these experiments, See PDF for Structure both solution and finely divided suspensions of hematin have been found equally effective in eliciting the phenomena of the paroxysm, and while it seems possible that a portion of the malarial pigment might be dissolved in the alkaline human serum, such an assumption is probably not essential. It might be objected that the toxic action of foreign hematin thus injected into the circulation would probably be greater than that of hematin derived from an animal's own blood, but as far as I have been able to determine, this objection does not seem valid, as rabbit hematin, dog hematin, and ox hematin produce in the rabbit effects that are alike in both character and degree. The dose of hematin remains as the one factor to which it is possible to attach some degree of uncertainty, but even here the author feels that the range of experimental conditions has been kept within the bounds of legitimate analogy with conditions existing in the human subject of malarial infection. Finally, the most conservative estimate of the value of such experiments points strongly to the fact that we have at least a potentially toxic substance in the pigment hematin as liberated by the malarial parasite into the circulation of the human host. There is also abundant evidence to show that the action of hematin is not confined to the paroxysmal phenomena of malaria, but that other features of the disease may find their explanation in the action of this pigment. For the present, however, it seems advisable to confine the discussion to this one phase of the question.

Mouse one-cell embryos undergoing a radiation-induced G2 arrest may re-enter S-phase in the absence of cytokinesis

2002 ◽  
Vol 80 (7) ◽  
pp. 618-624 ◽  
Author(s):  
P Jacquet ◽  
J Buset ◽  
J Vankerkom ◽  
S Baatout ◽  
L de Saint-Georges ◽  
...  
Keyword(s):  
Calyculin A ◽  
Embryonic Cells ◽  
G2 Arrest ◽  
Cell Stage ◽  
Chromosome Fragments ◽  
X Irradiation ◽  
Radiation Induced ◽  
Mouse Zygotes ◽  
The One

PCC (premature chromosome condensation) can be used for visualizing and scoring damage induced by radiation in the chromatin of cells undergoing a G1 or G2 arrest. A method involving the fusion of irradiated single embryonic cells with single MI oocytes was used to induce PCC in mouse zygotes of the BALB/c strain, which suffer a drastic G2 arrest after X-irradiation (dose used 2.5 Gy). Other G2-arrested embryos were exposed in vitro to the phosphatase inhibitor calyculin A. Both methods furnished excellent chromosome preparations of the G2-arrested embryos. The mean number of chromosome fragments did not change significantly during G2 arrest, suggesting that zygotes of this strain are unable to repair DNA damage leading to such aberrations. Forty to fifty percent of the irradiated embryos were unable to cleave after G2 arrest and remained blocked at the one-cell stage for a few days before dying. PCC preparations obtained from such embryos suggested that about 30% of them had undergone a late mitosis not followed by cytokinesis and had entered a new DNA synthesis. These results are discussed in the light of recent observations in irradiated human cells deficient in the p53/14-3-3sigma pathway.Key words: PCC, embryo, oocyte, calyculin A, G2 arrest, cytokinesis.

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