Low concentrations of metal mixture exposures have adverse effects on selected biomarkers of Xenopus laevis tadpoles

2015 ◽  
Vol 168 ◽  
pp. 19-27 ◽  
Author(s):  
Ertan Yologlu ◽  
Murat Ozmen
Keyword(s):  
Adverse Effects ◽  
Xenopus Laevis ◽  
Metal Mixture ◽  
Low Concentrations

scholarly journals Developmental changes of purinergic control of intestinal motor activity during metamorphosis in the African clawed frog, Xenopus laevis

2007 ◽  
Vol 292 (5) ◽  
pp. R1916-R1925 ◽  
Author(s):  
Monika Sundqvist
Keyword(s):  
Xenopus Laevis ◽  
Motor Activity ◽  
Receptor Antagonist ◽  
Circular Muscle ◽  
Developmental Changes ◽  
Disulfonic Acid ◽  
Developmental Phase ◽  
African Clawed Frog ◽  
Low Concentrations ◽  
Clawed Frog

Little is known about the purinergic regulation of intestinal motor activity in amphibians. Purinergic control of intestinal motility is subject to changes during development in mammals. The aim of this study was to investigate purinergic control of intestinal smooth muscle in the amphibian Xenopus laevis and explore possible changes in this system during the developmental phase of metamorphosis. Effects of purinergic compounds on mean force and contraction frequency in intestinal circular muscle strips from prometamorphic, metamorphic, and juvenile animals were investigated. Before metamorphosis, low concentrations of ATP reduced motor activity, whereas the effects were reversed at higher concentrations. ATP-induced relaxation was not inhibited by the P2-receptor antagonist pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS) but was blocked by the ecto-nucleotidase inhibitor 6- N, N-diethyl-d-β,γ-dibromomethylene ATP ( ARL67256 ), indicating that an ATP-derived metabolite mediated the relaxation response at this stage. Adenosine induced relaxation before, during, and after metamorphosis, which was blocked by the A1-receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). The stable ATP-analog adenosine 5′-[γ-thio]-triphosphate (ATPγS) and 2-methylthioATP (2-MeSATP) elicited contractions in the circular muscle strips in prometamorphic tadpoles. However, in juvenile froglets, 2-MeSATP caused relaxation, as did ATPγS at low concentrations. The P2Y11/P2X1-receptor antagonist NF157 antagonized the ATPγS-induced relaxation. The P2X-preferring agonist α-β-methyleneadenosine 5′-triphosphate (α-β-MeATP) evoked PPADS-sensitive increases in mean force at all stages investigated. This study demonstrates the existence of an adenosine A1-like receptor mediating relaxation and a P2X-like receptor mediating contraction in the X. laevis gut before, during, and after metamorphosis. Furthermore, the development of a P2Y11-like receptor-mediated relaxation during metamorphosis is shown.

scholarly journals Upstream domains of the Xenopus laevis rDNA promoter are revealed in microinjected oocytes.

1986 ◽  
Vol 6 (4) ◽  
pp. 1228-1234 ◽  
Author(s):  
J Windle ◽  
B Sollner-Webb
Keyword(s):  
Xenopus Laevis ◽  
Dna Sequences ◽  
Promoter Region ◽  
Core Promoter ◽  
Rrna Genes ◽  
Deletion Mutants ◽  
Low Concentrations ◽  
Upstream Promoter ◽  
Polymerase I ◽  
Vector Dna

The DNA sequences involved in promoting transcription of the Xenopus laevis rRNA genes were determined by microinjecting a series of deletion mutants into oocyte nuclei. A very small promoter region is sufficient to direct efficient transcription when templates are microinjected at high rDNA concentration, since 5'delta- 9 and 3'delta +6 templates are fully active. However, as the concentration of injected template is decreased, an increasing requirement for upstream domains, extending to nucleotide approximately -170, is observed. The major downstream border of the required region does not change. This apparently expanding 5' promoter border results from the fact that, as the rDNA concentration is decreased, transcription from templates lacking the upstream promoter domain falls off much more sharply than does transcription from a complete promoter. In fact, the deleted promoters are virtually inactive below a threshold rDNA concentration. It is indeed the rDNA concentration that is important, for coinjected vector DNA does not increase the level of transcription obtained from low concentrations of the 5' deletions. From these data we conclude that polymerase I transcription factors can recognize and initiate transcription from a small core promoter domain, but that sequences extending upstream to nucleotide approximately -170 increase the efficiency of initiation. A model is presented that could account for these results.

scholarly journals Joint Toxicity of a Multi-Heavy Metal Mixture and Chemoprevention in Sprague Dawley Rats

2020 ◽  
Vol 17 (4) ◽  
pp. 1451 ◽  
Author(s):  
Yafei Wang ◽  
Yuqing Tang ◽  
Zhou Li ◽  
Qihang Hua ◽  
Li Wang ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Adverse Effects ◽  
Inductively Coupled Plasma ◽  
Trisodium Citrate ◽  
Morris Water Maze Test ◽  
Spatial Learning And Memory ◽  
Joint Toxicity ◽  
Sprague Dawley ◽  
Metal Mixture

To explore the joint toxicity and bio-accumulation of multi-heavy metals and potential chemoprevention strategies, Male Sprague Dawley (SD) rats (n = 30) were treated orally once a week for six months with 500mg/kg•bw of eight heavy metals which were commonly identified in aquatic products in the Ningbo area including chromium, manganese, nickel, copper, zinc, cadmium, mercury, and lead. At the same time, 200mg/kg•bw of epigallocatechin-3-gallate (EGCG), trisodium citrate dihydrate (TCD) or glutathione (GSH) were administered to evaluate their antagonistic effects against adverse effects of multi-heavy metal mixture. The Morris water maze test was used to evaluate spatial learning and memory in the treated rats. Then the rats were anesthetized by pentobarbital sodium (40 mg/kg•bw) to obtain blood samples for biochemical analysis and organs (heart, liver, spleen, lungs, kidneys, brain, testis) to be conducted for biopsy and organ coefficients. Inductively coupled plasma mass spectrometer (ICP-MS) was used to analyze the concentrations of heavy metals. Results indicated that six months of exposure to a multi-heavy metal mixture under this experimental dosage resulted in accumulation in organs and adverse effects on the blood, reproductive system, and liver function. EGCG, TCD or GSH all showed certain chemoprevention effects against the joint toxicity induced by the multi-heavy metal mixture and indicated alleviation and the potential mechanism that also included the promotion of excretion of metals to which animals were exposed.

Identification of the oestrogenic isoflavones in fresh and fermented berseem clover (Trifolium alexandrinum)

1982 ◽  
Vol 33 (6) ◽  
pp. 951 ◽  
Author(s):  
MN Shehata ◽  
A Hassan ◽  
K El-Shazly
Keyword(s):  
Adverse Effects ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Rumen Fluid ◽  
Farm Animals ◽  
Biochanin A ◽  
Trifolium Alexandrinum ◽  
Low Concentrations ◽  
Berseem Clover ◽  
Layer Chromatography

A thin layer chromatography technique was used to identify and semiquantitate the oestrogenic isoflavones in berseem clover (Trifolium alexandrinum). Biochanin A and genistein were the most prominent isoflavones in all the three cuts of fresh berseem clover. Low concentrations of formononetin and daidzein were also detected. The concentrations of the all oestrogenic isoflavones gradually decreased in the successive cuts. Fermentation of all three fresh cuts in silo or in rumen fluid increased the concentrations of these isoflavones. Incubation of the silage materials with rumen fluid had little effect on the concentrations of the isoflavones. The concentrations of the oestrogenic isoflavones in fresh or fermented materials considered were too small to have any adverse effects on growth or reproduction of farm animals.

The effect of nicotine and cotinine on human gingival fibroblasts attachment to root surfaces

2015 ◽  
Vol 26 (5) ◽  
Author(s):  
Zeinab Rezaei Esfahrood ◽  
Amirhosein Zamanian ◽  
Maryam Torshabi ◽  
Maryam Abrishami
Keyword(s):  
Cell Adhesion ◽  
Adverse Effects ◽  
Control Group ◽  
Human Gingival Fibroblast ◽  
Gingival Fibroblast ◽  
Initial Cell ◽  
Low Concentrations ◽  
High Concentrations ◽  
Root Surfaces ◽  
Initial Cell Adhesion

AbstractDifferent compounds of smoking (e.g., nicotine and cotinine) are risk factors for various diseases such as oral cancer and periodontal diseases. Some studies reported the negative effects of nicotine on cell proliferation and differentiation. The present in vitro study assessed the effects of nicotine and cotinine (long-acting metabolite of nicotine) on the attachment and viability of human gingival fibroblast (HGF) cells to tooth root surfaces.A total of 70 teeth specimens were placed into 48-well culture plates and covered with HGF cell suspension, in complete Dulbecco’s modified Eagle’s medium culture medium containing 1 nM, 1 μm, 1 mM, and 5 mM of nicotine and cotinine concentrations. Cellular attachment and viability measured using an MTT assay and a scanning electron microscope were used for cell morphological evaluation.After 24 h, low (nanomolar and micromolar) and high concentrations (millimolar) of nicotine and cotinine caused a significant reduction in the initial cell adhesion in comparison with the control group, but no significant difference was observed between the nicotine and the cotinine groups (p<0.05). Dentally attached cells with low concentrations of nicotine and cotinine proliferated 48 h after exposure, the same as the control group. However, dentally attached cells with high concentrations of nicotine and cotinine (especially 5 mM) did not proliferate 24 h after exposure (p<0.05).Low concentrations of nicotine and cotinine caused a reduction in the initial cell adhesion. However, no significant adverse effects on the proliferation of attached cells were seen in the longer period. High concentrations of nicotine and cotinine have adverse effects on the cell adhesion and proliferation of HGF cells.

Thyroid disruption by technical decabromodiphenyl ether (DE-83R) at low concentrations in Xenopus laevis

2010 ◽  
Vol 22 (5) ◽  
pp. 744-751 ◽  
Author(s):  
Xiaofei Qin ◽  
Xijuan Xia ◽  
Zhongzhi Yang ◽  
Shishuai Yan ◽  
Yaxian Zhao ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Decabromodiphenyl Ether ◽  
Low Concentrations ◽  
Thyroid Disruption
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