Malformations Of Embryos Research Articles

Developmental toxicity of an emerging organophosphate ester Bis-(2-ethylhexyl)-phenyl phosphate on embryonic zebrafish: Comparison to 2-ethylhexyl diphenyl phosphate

Bis-(2-ethylhexyl)-phenyl phosphate (BEHPP) and its structural analog, 2-ethylhexyl diphenyl phosphate (EHDPP), are widely present in the environment. However, their toxic effects, particularly developmental toxicity, remain poorly understood. In this study, we evaluated the impacts of BEHPP and EHDPP on multiple developmental endpoints in zebrafish. BEHPP did not lead to mortality and malformations of embryos within the test concentration range (0.5–4.0 μM). In contrast, EHDPP had significant lethal effects, with an LC50 of 2.44 μM, and induced malformations, notably pericardial edema (PE), with an EC50 of 1.77 μM. In addition, BEHPP induced cardiac dysfunctions in embryos to a similar degree as EHDPP. Both stroke volume and cardiac output were significantly increased at BEHPP concentrations of 1.8 nM and above and at EHDPP concentrations of 4.3 nM and above. Transcriptomic analysis further corroborated the similar disturbance at the molecular level for both substances and revealed the Key Events (KEs) in the cardiac toxic regulation, including the focal adhesions, ECM-receptor interaction, cardiac muscle contraction, and the adrenergic signaling in cardiomyocytes. Taken together, the present study provided novel insights into the adverse effects of these emerging organophosphate esters and highlighted their potential risks to embryonic development in both ecosystems and humans.

Florfenicol induces malformations of embryos and causes altered lipid profile, oxidative damage, neurotoxicity, and histological effects on gonads of adult sea urchin, Paracentrotus lividus

The frequent occurrence of antibiotics in the aquatic environment has engendered negative impacts on non-target organisms. The effects of the veterinary antibiotic florfenicol (FLO) during the embryo-larval development of the sea urchin, Paracentrotus lividus was assessed using four increasing concentrations (1, 2, 5 and 10 mg/L). Furthermore, FLO toxicity to adults was investigated through the analysis of oxidative damage, histopathological alterations, lipid metabolism and acetylcholinesterase activity following an exposure period of 96 h. FLO induced embryotoxicity with estimated EC50 values of 5.75, 7.56 and 3.29 mg/L after 12 h, 24 h and 48 h, respectively. It generated oxidative stress assessed as lipid peroxidation in gonads despite the increased antioxidant activity of catalase (CAT). Neurotoxicity was also evident since the AChE activity significantly decreased. Moreover, FLO affected the lipid metabolism by increasing saturated fatty acid (SFA) and monounsaturated fatty acid proportions (MUFA), except in the group exposed to 5 mg/L. The increase in polyunsaturated fatty acid (PUFA) levels and docosahexaenoic acid (DHA, C22:6n-3) proportions were noted with all FLO concentrations. Eicosapentaenoic acid (EPA, C20:5n-3) decreased, while arachidonic acid (ARA, C20:4n-6) increased in sea urchins exposed to 5 and 10 mg/L FLO. Histopathological alterations of gonadal tissues represent an additional confirmation about the toxicity of this antibiotic that might decrease the reproductive performance of this species. Nevertheless, even if reproduction of sea urchins would be partially successful, the embryotoxicity would compromise the normal development of the embryos with consequences on the population.

Histopathological effects of retinol on blastocyst implantation in pregnant rats

Retinol is lipid soluble vitamin widely used during pregnancy as a food supplement.The study has been conducted in Animal House/Faculty of Sciences/University of Kufa between December 2021 and February 2022, fifteen female Albino Rats are used. The present study has been intended to show the histolopathologiacl effects of retinol on blastocyst implantation in female Albino Rats. The females Rats are randomly divided into three main groups, comprising five rats for each group. The control group is given orally injection of physiological normal saline and the second and third group are given orally injection of retinol doses ten, twenty μcg/kg/day respectively for seven days from the first day to the end of experimental allocated for each female.The rats are sacrificed in 7 th (dpc) to study the implantation of embryos in decidual tissues. Retinol doses ten, twenty μcg/kg/day caused macroscopic malformations in embryos of female rats compare to control group. The histopathlogical study of female rats embryos treated with ten, twenty μcg/kg/day of retinol have shown deformations of decidual tissues zonation.In conclusion; retinol caused malformations of embryos in 7 th (dpc) and histopathlogical effects in decidual tissue zonations of blastocyst.

Teratogenic effects of vitamin A on embryos of pregnant rats

Vitamin A is lipid soluble vitamin widely used during pregnancy as a food supplement. The study has been conducted in Animal House/Faculty of Sciences/University of Kufa between December 2021 and February 2022, thirty female Albino Rats are used. The present study has been intended to show the teratogenic effects of Vitamin A on embryos in female Albino Rats. The females Rats are randomly divided into four main groups,The first and second control groups are given orally injection of physiological normal saline and the third group 15th (dpc) are given orally injection of vitamin A doses ten, twenty μcg/kg/day respectively for fifteen days from the first day to the end of experimental allocated for each female. The fouth group 20 th (dpc) are given orally injection of vitamin A doses ten, twenty μcg/kg/day respectively for tewnty days from the first day to the end of experimental allocated for each female. The rats are sacrificed in 15,20 th (dpc) to study the teratogenic effects on embryonic bodies.Retinol doses ten, twenty μcg/kg/day caused macroscopic malformations in embryos of female rats compare to control group.In conclusion; Vitamin A caused malformations of embryos in 15 th and 20 th (dpc).

Toxicity of boron and vanadium nanoparticles on Danio rerio embryos - Phenotypical, biochemical, and behavioral alterations.

Engineered nanoparticles (NPs) are emerging contaminants of concern and it is important to understand their environmental behavior and ecological risks to exposed organisms. Despite their ubiquitous presence in the environment, there is little information about the hazards of certain NPs, such as boron (BNPs) and vanadium (VNPs). The aim of the present research was to investigate the effects of commercial BNPs and VNPs (80 to 100 nm) to zebrafish embryos, at different levels of biological organization. A range of nominal concentrations for both NPs (0, 0.01, 0.1, 1, and 10mg/L) was tested. Due to the presence of triton X-100 in the NPs' stock dispersions, an additional control group was included (0.001% triton X-100). Survival, hatching, and malformations of embryos were assessed for 96 hours (h) exposure. Locomotor behavior was evaluated at 120 h. Furthermore, embryos were exposed to 0, 1, and 10 mg/L of NPs to evaluate a set of biomarker responses after 96 h: cholinesterase (ChE) and glutathione S-transferase (GST) activities, total glutathione (TG) and energy budgets levels. VNPs induced malformations (10 mg/L), hyperactivity (10 mg/L), erratic swimming (0.01 mg/L), altered swimming pattern (>0.01 mg/L), delayed hatching (10 mg/L) and altered biochemical responses involved in antioxidant defense (GST and TG at >1 mg/L), neurotransmission (ChE at 10 mg/L) and energy metabolism (lipids at >1 mg/L and carbohydrates at 10 mg/L). BNPs caused malformations (10 mg/L), affected swimming pattern (>0.01 mg/L), induced erratic swimming (10 mg/L) and decreased TG content and GST activity (>1 mg/L). At the same concentrations, VNPs affected a greater number of endpoints than BNPs, demonstrating a greater toxicity to zebrafish embryos. The present study shows that BNPs and VNPs may affect aquatic organisms, albeit at relatively great non-environmentally relevant concentrations, reinforcing the importance of the risk assessment of different NPs.

Lambda-cyhalothrin-loaded nanocapsules pose an unacceptable acute toxicological risk to zebrafish (Danio rerio) at the adult and larval stages but present an acceptable risk to embryos

Recently, size-controlled pesticide microcapsule (MC) delivery systems have played an important role in precision farming development; however, the potential environmental hazards of MCs with different particle sizes have not been fully characterized. In this study, we prepared a series of lambda-cyhalothrin (LC)-MCs with nano and micron-scale capsule sizes (average diameters of 209.4 nm, MC-N; 2.41 µm, MC-S; 4.87 µm, MC-M; and 12.41 µm, MC-L). The assessment results showed that the release and sedimentation behavior of LC-MCs in water and toxicity to zebrafish at three life stages were all particle size-dependent. As the diameter distribution of approximately 100 nm extended to the micron scale (~27 µm), the capsules released more slowly and sunk more quickly in water. In addition, micron-sized LC-MC exposure resulted in significantly less fish mortality and malformations of larvae and embryos compared with nanosized LC-MC exposure. The highest accumulation of MC-N in the gill and the severest toxicity to larvae suggested that the smaller size and stronger permeability of nanocapsules would pose unpredictable consequences for nontargeted organisms. The obvious toxicological differences of LC-MCs toward aquatic organisms implies that regulating MC production in an appropriate size range is an important prerequisite for achieving efficient but safe pesticide applications.

Response of Human Glioblastoma Cells to Vitamin B12 Deficiency: A Study Using the Non-Toxic Cobalamin Antagonist.

Simple SummaryThe most important biological function of vitamin B12 (cobalamin) is to accomplish DNA synthesis, which is necessary for cell division. Cobalamin deficiency may be especially acute for rapidly dividing cells, such as glioblastoma cells. Therefore, cobalamin antagonists offer a medicinal potential for developing anti-glioma agents. In the present study, we revealed, for the first time, that the induction of cobalamin deficiency by vitamin B12 antagonist with affinity to key transporter of cobalamins, inhibited glioblastoma cells growth and promoted cell cycle arrest. The effect was observed for non-toxic concentration of the agent, as demonstrated on zebrafish. Moreover, as compared to our previous study, the cytostatic effect of the agent was more pronounced in glioblastoma cells than in normal astrocytes. We believe that the study may become the basis for further in vitro and in vivo experiments concerning cobalamin deprivation as a potential therapeutic strategy for glioblastoma.The most important biological function of vitamin B12 is to accomplish DNA synthesis, which is necessary for cell division. Cobalamin deficiency may be especially acute for rapidly dividing cells, such as glioblastoma cells. Therefore, cobalamin antagonists offer a medicinal potential for developing anti-glioma agents. In the present study, we developed an in vitro model of cobalamin deficiency in glioblastoma cells. Long-term treatment of cells with the cobalamin analogue, hydroxycobalamin [c-lactam] (HCCL) was applied to induce an increase of hypocobalaminemia biomarker. Cytometric assays demonstrated that vitamin B12 promoted glioblastoma cells proliferation, whereas the treatment of cells with HCCL caused a dramatic inhibition of cell proliferation and an induction of cell cycle arrest at the G2/M phase. Vitamin B12 counteracted all the observed effects of HCCL. In the in silico study, we characterized the molecular interactions between HCCL and transcobalamin II (TCII). We have demonstrated that HCCL shares similar interactions with TCII as naturally occurring cobalamins and therefore may act as a competitive inhibitor of this key transporter protein. We assessed the impact of HCCL on the mortality or developmental malformations of zebrafish embryos. Collectively, our findings suggest that the use of cobalamin transport antagonists as potential anti-glioma agents would be worth exploring further.

Individual and mixture toxicity of chromium and copper in development, oxidative stress, lipid metabolism and apoptosis of Bufo gargarizans embryos

In natural ecosystems, living organisms are always subjected to a mixture of multiple heavy metals exposure, yet it is more common to study the effect of individual, rather than combined exposure. This study assessed the impacts of single or combined exposure to Cr and Cu on embryonic development, oxidative stress, lipid metabolism and apoptosis in the early development of Bufo gargarizans embryos. The total length, development stage and malformations of embryos were measured, and the mRNA expression of genes related to oxidative stress, lipid metabolism and apoptosis at Gs 18 and Gs 22 were determined by RT-qPCR. The results showed that all treatments significantly reduced the total length of embryos, delayed the stage of embryonic development and increased the proportion of malformed embryos. The Cr-Cu mixture treatment showed the greatest suppression of embryonic development and induced the highest rate of embryo malformation, compared to individual Cr and Cu treatments. In addition, the expression levels of oxidative stress genes (HSP90, SOD and GPx) and fatty acid β-oxidation-related genes (ACOXL, ECHS1 and SCP) showed an up-regulated trend in treatments compared to control groups. Conversely, the lipid synthesis-related mRNA gene expressions (KAR, TECR, ACSL3 and ACSL4) were down-regulated. Among them, the Cr-Cu mixture had the greatest impact on lipid metabolism gene expression. The treatments showed significant effects on the expression of apoptosis genes (Bcl-1 and Bax), with Bcl-1 mRNA expression increasing and Bax mRNA expression decreasing. These results indicated that exposure to individual Cr, Cu and a Cr-Cu mixture can lead to oxidative stress, disrupt lipid metabolism and promote apoptosis, and the Cr-Cu mixture could cause more serious negative effects on B. gargarizans embryos than Cr or Cu individually.

ВЛИЯНИЕ ФАКТОРОВ ВНЕШНЕЙ СРЕДЫ НА РАЗВИТИЕ ЭМБРИОНА, ЕГО ИММУННЫЙ СТАТУС И РЕЗУЛЬТАТЫ ИНКУБАЦИИ

The article is devoted to the study of the problem of external factors influence on the development of the embryo and the immune status of chickens. This is primarily due to the fact that the sensitivity of embryos to the impact of various damaging agents of the external environment, primarily abiotic factors, such as oxygen deficiency, sharp temperature fluctuations beyond the optimum, mechanical damage and other influences, affect the course of morphogenetic processes, disrupting the rate of development of individual organs, causing the appearance of malformations of embryos and, in many cases, leading to death. The object of the study is chicken embryos and chickens up to ten days old. The aim of the work was to develop the most optimal incubation technology that would help stimulate the development of chicken embryos and did not require additional equipment and training costs. The work consists of an introduction, article materials, conclusions and a list of references. The introduction includes the relevance of the research, its goals and objectives, object, subject of research and research methods. The first section describes research on the correct selection, storage of eggs and the correct use of the incubator. The second section contains data on the study of the influence of various factors on the immune system of chicken embryos and chickens. In general, the analysis of factors given in the literature allows us to conclude about the influence of these factors on the development of chickens, increasing their safety and productivity. The material of the article shows that, while studying these factors, they primarily affect the immune system.

Acute Toxicity of Imidacloprid on the Developmental Stages of Common Carp Cyprinus carpio

The objective of the present study was to elucidate the toxic effects of imidacloprid on the embryonic and larval stages of common carp (Cyprinus carpio). Each of the 1000 fertilized eggs and larvae were exposed to six different concentrations (0, 10, 30, 100, 300, and 1000 µg/L) of imidacloprid in 30 plastic bowls. Each of the control and treatment was maintained in five replicates. Results showed that hatching rate of fertilized eggs and number of dead embryos and larvae significantly decreased with increasing imidacloprid concentrations. The 24-, 48-, and 72-h LC50 value of imidacloprid for common carp embryos were estimated to be 12,708.8, 611, and 274.9 µg/L, respectively and the 24-, 48-, 72-, and 96-h LC50 of imidacloprid for common carp larvae were estimated to be 93719, 21691, 2352.7, and 1292.6 µg/L, respectively. Furthermore, results showed several malformations of common carp embryos and larvae induced by the toxicity of imidacloprid when exposed to 300 and 1000 µg/L. The results suggest that the minimum concentration of 10 µg/L imidacloprid in the aquatic environment may have adverse effects on the embryonic and larval stages of common carp.

Endocrine disruption, oxidative stress and lipometabolic disturbance of Bufo gargarizans embryos exposed to hexavalent chromium

The aim of the current study was to determine the potential developmental and metabolic abnormalities caused by Cr (VI) exposure on Bufo gargarizans (B. gargarizans) embryos. B. gargarizans embryos were treated with different concentrations of Cr (VI) (13, 52, 104, 208, and 416 μg Cr6+ L−1) for 6 days. Morphological abnormalities, total length, weight and developmental stage were monitored. Malformations of embryos were also examined using scanning electron microscopy (SEM). In addition, the transcript levels of several genes associated with lipid metabolism, oxidative stress, and thyroid hormones signaling pathways were also determined. Our results showed a time-dependent inhibitory effect of Cr (VI) on the growth and development of B. gargarizans embryos. On day 4, total length, weight, and developmental stage were significantly lower at 416 μg Cr6+ L−1 relative to control embryos. On day 6, significant reductions in total length, weight, and developmental stage were observed at 104, 208, and 416 μg Cr6+ L−1. Malformed embryos were found in all Cr (VI) treatments, which were characterized by axial flexures, yolk sac edema and rupture, surface tissue hyperplasia, stunted growth, wavy fin and fin flexure. RT-qPCR results showed that exposure to Cr (VI) down-regulated TRβ and Dio2 mRNA expression and up-regulated Dio3 mRNA level at 416 μg Cr6+ L−1. The transcript levels of SOD and GPx were upregulated at 52, 208, and 416 μg Cr6+ L−1, while the transcript level of HSP90 was downregulated at 52, 208, and 416 μg Cr6+ L−1. Also, mRNA expression of lipid synthesis-related genes (FAE and ACC) were significantly downregulated in embryos treated with 208 and 416 μg Cr6+ L−1, but mRNA expression of fatty acid β-oxidation-related genes (ACOX, CPT, and SCP) was significantly upregulated at 416 μg Cr6+ L−1. Therefore, our results suggested that Cr (VI) could disrupt thyroid endocrine pathways and lipid synthesis, leading to the inhibition of growth and development in B. gargarizans embryos. Furthermore, the decreased ability of scavenging ROS induced by Cr (VI) might be responsible for the teratogenic effects of Cr (VI).

The importance of sediments in ecological quality assessment of stream headwaters: embryotoxicity along the Nidda River and its tributaries in Central Hesse, Germany

BackgroundAlthough the crucial importance of sediments in aquatic systems is well-known, sediments are often neglected as a factor in the evaluation of water quality assessment. To support and extend previous work in that field, this study was conducted to assess the impact of surface water and sediment on fish embryos in the case of a highly anthropogenically influenced river catchment in Central Hesse, Germany.ResultsThe results of 96 h post fertilisation fish embryo toxicity test with Danio rerio (according to OECD Guideline 236) revealed that river samples comprising both water and sediment exert pivotal effects in embryos, whereas surface water alone did not. The most prominent reactions were developmental delays and, to some extent, malformations of embryos. Developmental delays occurred at rates up to 100% in single runs. Malformation rates ranged mainly below 10% and never exceeded 25%.ConclusionA clear relationship between anthropogenic point sources and detected effects could not be established. However, the study illustrates the critical condition of the entire river system with respect to embryotoxic potentials present even at the most upstream test sites. In addition, the study stresses the necessity to take into account sediments for the evaluation of ecosystem health in industrialised areas.

PECULIARITIES OF THE TOXIC EFFECT OF DIISONONYL PHTHALATE PLASTICIZER PHTHALATE ON EXPERIMENTAL MODELS

Introduction. The purpose of the study was to determine the characteristics of the biological effect of diisononyl phthalate, a new plasticizer for polymer products. Material and methods. Toxic properties of the compound have been studied in various ways of its entering in the organism of laboratory animals, local irritating, cumulative and skin-resorptive actions have been established, the potential ability of the compound to induce remote effects in experimental models in vivo/in vitro has been revealed. Results and discussion. The obtained data show diisononyl phthalate do not pose a risk of the acute poisoning under intragastric, intraperitoneal, epicutaneous and inhalation modes of exposure, being incapable of inducing signs of the irritation of the skin and mucous membranes, is not allergic. With subchronic intragastric administration of diisononyl phthalate in doses from 10,000 to 100 mg/kg, the dose dependence of toxic effect and its ability to cause chronic polytropic poisoning of the action in the form of disturbance of the pattern of peripheral blood, calcium and phosphorus metabolism and changes in the functional state of internal organs are revealed. In the study of the reproductive toxicity against the background of the administration of the drug at a dose of 10,000 mg/kg, an increase in total postimplantation, embryonic and the postnatal mortality rate was established. Intragastric administration of diisononyl phthalate at the mentioned dose to female animals during pregnancy triggered the formation of multiple (combined), external and internal malformations of embryos that were single in response to a reduced dose of up to 100 mg/kg. Changes in the state of the reproductive function of males have not been established. In the study of mutagenic toxicity in the Ames test, the effect of the compound has not been established to lead to an increase in the number of revertant colonies, which indicates the lack of ability of diisononyl phthalate to induce point mutations. Conclusion. The results of the studies showed that further study of the toxic effect of diisononylphthalate in chronic exposure and in vitro tests is necessary.

Teratogenic hazard of BPEI-coated silver nanoparticles to Xenopus laevis

Silver nanoparticles (AgNPs) are among the most exploited antimicrobial agents and are used in many consumer products. Size and surface reactivity are critical physico-chemical properties responsible for NPs toxicity, and surface coatings, often used to functionalize or stabilize AgNPs, can influence their toxic profile and biocompatibility. In the current study the developmental toxicity of (1) negatively charged citrate-coated AgNPs (Cit-AgNPs), (2) positively charged branched polyethylenimine-coated AgNPs (BPEI-AgNPs), and (3) Ag+ (from 0.0625 to 0.75 mg Ag/L) was investigated by the standard Frog Embryo Teratogenesis Assay – Xenopus (FETAX). In order to identify the most sensitive developmental phase, embryos were also exposed during different embryonic stages. Morphological and bio-physical studies were performed to characterize tissue lesions and NP uptake. The results suggest that Ag+ was strongly embryo-lethal. Contrary to Cit-AgNPs, the positively charged BPEI-AgNPs exert a concentration-dependent effect on lethality and malformations of embryos. The BPEI-AgNPs showed the highest teratogenic index (TI = 1.6), pointing out the role of functional coating in determining the developmental hazard. The highest susceptibility to BPEI-AgNPs was during early embryogenesis, when embryos are still enclosed in the fertilization envelope, and the post-stomodeum opening stages, when NPs ingestion occurs. In BPEI-AgNPs treated larvae, the histological examination revealed irregular intestinal diverticula coupled with edematous connective tissue. Small NPs aggregates are mapped throughout the intestinal mucosa and secondary target organs by two-photon excitation microscopy. We conclude that a teratogenic risk may be associated with BPEI-AgNPs exposure, but the modality of NP-tissue interactions and the teratogenic mechanism need further investigations to be better defined.

Assessment of sediment toxicity in the Lagoon of Venice (Italy) using a multi-species set of bioassays

Within the framework of a Weight of Evidence (WoE) approach, a set of four toxicity bioassays involving the amphipod Corophium volutator (10 d lethality test on whole sediment), the sea urchin Paracentrotus lividus (fertilization and embryo toxicity tests on elutriate) and the pacific oyster Crassostrea gigas (embryo toxicity test on elutriate) was applied to sediments from 10 sampling sites of the Venice Lagoon (Italy). Sediments were collected during three campaigns carried out in May 2004 (spring campaign), October 2004 (autumn campaign) and February 2005 (winter campaign). Toxicity tests were performed on all sediment samples. Sediment grain-size and chemistry were measured during spring and autumn campaigns. This research investigated (i) the ability of toxicity tests in discriminating among sites with different contamination level, (ii) the occurrence of a gradient of effect among sampling sites, (iii) the possible correlation among toxicity tests, sediment chemistry, grain size and organic carbon, and (iv) the possible occurrence of toxicity seasonal variability. Sediment contamination levels were from low to moderate. No acute toxicity toward amphipods was observed, while sea urchin fertilization was affected only in few sites in just a single campaign. Short-term effects on larval development of sea urchin and oyster evidenced a clear spatial trend among sites, with increasing effects along the axis connecting the sea-inlets with the industrial area. The set of bioassays allowed the identification of a spatial gradient of effect, with decreasing toxicity from the industrial area toward the sea-inlets. Multivariate data analysis showed that the malformations of oyster embryos were significantly correlated to the industrial contamination (metals, polynuclear aromatic hydrocarbons, hexachlorobenzene and polychlorinated biphenyls), while sea urchin development to sediment concentrations of As, Cr and organic carbon. Both embryo toxicity tests were significantly affected by high ammonia concentrations found in the elutriates extracted from some mudflat and industrial sediments. No significant temporal variation of the toxicity was observed within the experimental period. Amendments to the set of bioassays, with inclusion of chronic tests, can certainly provide more reliability and consistency to the characterization of the (possible) toxic effects.

A representative retinoid X receptor antagonist UVI3003 induced teratogenesis in zebrafish embryos.

Retinoid X receptor (RXR) interfering activity has been detected in different water resources. To study RXR disruptor-induced toxicological effects on vertebrates, embryos of zebrafish (Danio rerio) were exposed to a representative RXR antagonist UVI3003. Results showed that the teratogenic index (LC50 /EC50 ) of UVI3003 was as high as 5.4. UVI3003 induced multiple malformations of embryos, including deformed fins, reduced brains, small jaws, bent tails and edema in hearts, the degree of which became more severe with increasing exposure concentration. Although no significant difference was observed in the hatching rates between the exposure group and control, the whole body length was significantly reduced by 6.5% and 8.9% when exposed to 200 and 300 µg l(-1) of UVI3003, respectively. The heart rate also significantly decreased by 8.8-50.2% during exposure. Further experiments revealed that the pharyngula stage was the most sensitive development phase in terms of embryo response to UVI3003. The results demonstrated severe teratogenicity of RXR antagonist in zebrafish embryos and provided important data for ecotoxicological evaluation of RXR antagonists.

Involvement of JNK in the Embryonic Development and Organogenesis in Zebrafish

c-Jun N-terminal kinase (JNK) is one of the mitogen-activated protein kinases. Previous studies showed that the JNK is involved in signaling pathways initiating cell cycle, and eventually, causing apoptosis through persistent activation in mammals. In this article, it is further revealed that the jnk1 gene is closely related with the embryonic development and organogenesis in zebrafish. RT-PCR and Western blot analysis show that there were distinct expression patterns of JNK at the different developmental stages as well as in the various tissues in zebrafish. Knockdown of jnk1 by RNA interference (RNAi) resulted in high lethal, serious retardation and malformations of embryos in zebrafish. SP600125, a JNK-specific inhibitor, gives rise to high mortality in zebrafish, similar to that caused by the jnk1 RNA interference. SP600125 is also responsible for the severe abnormality of organs, especially the skeletal system, such as skull, mandible deficiency, and cyrtosis heterauxesis. The results also indicate that the inhibition of JNK by SP600125 suppresses the ovarian differentiation during the embryo development in zebrafish. Overall, our study demonstrates that the jnk1 gene is required for ovary differentiation and development in the zebrafish, and down-regulated JNK directly inhibits ovary differentiation during early ontogenetic stages.

Exogenous Nucleotides Antagonize the Developmental Toxicity of EthanolIn Vitro

The objective of this study was to assess whether nucleotides supplementation in vitro could suppress ethanol-induced developmental toxicity in mouse. The models of whole embryo culture (WEC) and midbrain (MB) cell micromass culture were used in this study. In WEC system, exposure to 4.0 mg/mL ethanol for 48 h yielded various developmental malformations of the mice embryos. Nucleotides supplementation (0.16, 0.80, 4.00, 20.00, and 100.00 mg/L) improved the growth parameters to some extent, and the protective effects peaked at 4.00 mg/L. In MB cell micromass culture system, exposure to 4.0 mg/mL ethanol for 5 days resulted in suppression of proliferation and differentiation. Supplementation of nucleotides (0.16, 0.80, 4.00, 20.00, and 100.00 mg/L) showed some protective effects, which peaked at 4.00 mg/L, too. The present research indicated that nucleotides supplementation might be of some benefit in the prevention of ethanol-induced birth defects; however, appropriate dosage requires attention.

The Effect of β-Carotene Against Adriamycin Toxicity on the Embryo Formation

Adriamycin is an anthracycline antibiotic widely used for the treatment of many types of cancer. The cytotoxic effect of Adriamycin occurs by a free radical-mediated mechanism. Thus, to prevent or reduce the toxic effect of Adriamycin, it is possible to use it in combination with antioxidants. The aim of this study was to evaluate a potential effect of β-carotene against Adriamycin-induced toxicity on the embryo formation. Pregnant rats were treated with Adriamycin, β-carotene, and their combination during the critical stages of embryogenesis. The first group was control group. Adriamycin was administered on day 9 (group 2a) and day 12 (group 2b) of gestation by a single intraperitoneal injection at a dose of 5 mg/kg. β-Carotene was given at a dosage of 0.6 mg/(kg·day) from day 6 to 10 or from day 9 (group 3a) to 13 (group 3b) of gestation 5 times per os; in the case of their combination, β-carotene was given per os 3 times before Adriamycin injection, one time simultaneously with Adriamycin and one time after its injection (groups 4a and 4b). Animals were euthanized on day 21 of gestation. Embryo resorptions and alive fetuses were counted, weighed, and measured. The embryos of each litter were examined macroscopically after the Buen solution fixation for the embryo defects. In order to render the skeleton visible, the soft tissues were macerated using caustic soda, stained with alizarin red, and cleared with glycerin. Adriamycin induced embryotoxicity; the combination of Adriamycin and β-carotene decreased the number of Adriamycin-induced embryo resorptions about two times. A gavage with Adriamycin alone decreased fetal body weights (P<0.05), while giving it in combination, the fetal body weight was similar to that in the control group. Adriamycin induced the retardation of skeletogenesis and external fetal malformations (microphthalmia, hydrocephaly, anencephaly, and others). After an exposure to β-carotene, external malformations (diaphragmatic hernia) of embryos were found only occasionally. β-Carotene in combination with Adriamycin produced no positive effect on Adriamycin-induced skeletodysgenesis or external malformations. Antioxidant β-carotene in combination with Adriamycin slightly reduced the Adriamycin-induced embryotoxicity, but produced no positive effect on Adriamycin-induced skeleto-dysgenesis or external malformations.

Developmental toxicity, uptake and distribution of sodium chromate assayed by frog embryo teratogenesis assay- Xenopus(FETAX)

The embryotoxicity and teratogenicity of Cr(VI) on the survival and morphology of the anuran Xenopus laevis have been assessed by frog embryo teratogenesis assay- Xenopus (FETAX). The lethal median (LC 50) and teratogenic median (TC 50) concentration values of Cr(VI) were 890 µM and 260 µM, respectively. The calculated teratogenic index (TI) value was 3.42, suggesting that hexavalent chromium has a teratogenic potential. Malformations of embryos included lifting of the body, coiling of the tail and body oedema. Furthermore, the chromium salt caused significant growth retardation at 25 µM exposure concentrations. The use of radiolabelled 51Cr(VI) allowed the determination of the time course uptake of Cr in Xenopus exposed to concentrations ranging from 0.025 to 500 µM. The evaluation of its distribution into the body (head–abdomen–tail) was evaluated at different exposure times. Chromium is taken up at 24 h by Xenopus embryos for all concentrations tested. At 48 h post fertilization (stage of larva) the amount of Cr accumulated by the two-day-old larva ranged from 0.42 to 580 pg mg − 1 wet weight at 0.025 and 500 µM respectively. These amounts were lower than those at 24 h (2.77 to 11016 pg mg − 1 wet weight embryo) reaching values of the same order of magnitude at 120 h (five-days-old larva). Since at 48 h Xenopus development leads to a swimming embryo, the observed uptake at 24 h could be the result of the binding of Cr to jelly coat compounds surrounding the embryo body as confirmed by gel filtration experiments on 51Cr-jelly coat. The interaction of Cr with jelly coat is in agreement with the role of jelly coat in protecting the embryo against pathogen and chemical toxins to ensure fertilization. This work further supports the hypothesis that Cr contamination of surface waters could contribute to explain the reported worldwide depletion of frog population.