Bifidobacteria in disease: from head to toe

Bifidobacteria as a strictly anaerobic gram-positive bacteria, is widely distributed in the intestine, vagina and oral cavity, and is one of the first gut flora to colonize the early stages of life. Intestinal flora is closely related to health, and dysbiosis of intestinal flora, especially Bifidobacteria, has been found in a variety of diseases. Numerous studies have shown that in addition to maintaining intestinal homeostasis, Bifidobacteria may be involved in diseases covering all parts of the body, including the nervous system, respiratory system, genitourinary system and so on. This review collects evidence for the variation of Bifidobacteria in typical diseases among various systems, provides mild and effective therapeutic options for those diseases that are difficult to cure, and moves Bifidobacteria from basic research to further clinical applications.

M6A transcriptome-wide map of circRNAs identified in the testis of normal and AZ-treated Xenopus laevis

BACKGROUND

Evidence showed that N6-methyladenosine (m6A) is strongly associated with male germline development. However, the role of m6A methylation on circRNAs in amphibians remains unknown. In this study, we conducted m6A sequencing analysis to explore the m6A transcriptome-wide profile of circRNAs in testis tissues of Xenopus laevis (X. laevis) with and without treatment with 100 µg/L atrazine (AZ).

RESULTS

The analysis showed that m6A modification of circRNAs enriched in sense overlapping in testes of X. laevis. We identified the differential m6A modification sites within circRNAs in testes of AZ-exposed X. laevis and compared that with animals from control group. The results showed that a total of 1507 methylated m6A sites was induced by AZ (760 up-methylated and 747 down-methylated). The cross-analysis exhibited a negative correlation of differentially methylated m6A peaks and circRNAs expression level. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that 20 key pathways may be involved in the mechanism of testis damage of AZ-exposed X. laevis.

CONCLUSIONS

These findings indicated that differentially m6A-methylated circRNAs may play important roles in abnormal testis development of AZ-exposed X. laevis. This study is the first report about a map of m6A modification of circRNAs in male X. laevis and provides a basis for further studying on the function and mechanism of m6A methylation of circRNAs in the testis development of amphibian.

Baicalin alleviates silica-induced lung inflammation and fibrosis by inhibiting TLR4/NF-?B pathway in rats

Silicosis is an occupational lung disease caused by inhaling silica dust. The disease is characterized by early lung inflammation and late irreversible pulmonary fibrosis. Here we report the effect of Baicalin, a main flavonoid compound from the roots of Chinese herbal medicine Huang Qin on silicosis in a rat model. Results showed Baicalin (50 or 100 mg/kg/day) can mitigate the silica-induced lung inflammation and reduce the harm of alveolar structure and the blue region of collagen fibers in rat lung at 28 days after administration. At the same time, Baicalin also diminished the level of interleukin-1beta (IL-1beta, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) in lung tissues. The protein expression of collagen I (Col-1), alpha-smooth muscle actin (alpha-SMA) and vimentin were down-regulated while E-cadherin (E-cad) was increased in Baicalin-treated rats. In addition, the Toll Like Receptor 4 (TLR4)/ nuclear factor kappaB (NF-kappaB) pathway was enabled at 28 days after silica infusion, and the treatment of Baicalin diminished the expression of TLR4 and NF-?B in the lungs of rat with silicosis. These results suggested that Baicalin inhibited the pulmonary inflammatory and fibrosis in a rat model of silicosis, which could be attributed to inhibition of the TLR4/NF-kappaB pathway.

Baicalin alleviates silica-induced lung inflammation and fibrosis by inhibiting TLR4/NF-?B pathway in rats

Silicosis is an occupational lung disease caused by inhaling silica dust. The disease is characterized by early lung inflammation and late irreversible pulmonary fibrosis. Here we report the effect of Baicalin, a main flavonoid compound from the roots of Chinese herbal medicine Huang Qin on silicosis in a rat model. Results showed Baicalin (50 or 100 mg/kg/day) can mitigate the silica-induced lung inflammation and reduce the harm of alveolar structure and the blue region of collagen fibers in rat lung at 28 days after administration. At the same time, Baicalin also diminished the level of interleukin-1beta (IL-1beta, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) in lung tissues. The protein expression of collagen I (Col-1), alpha-smooth muscle actin (alpha-SMA) and vimentin were down-regulated while E-cadherin (E-cad) was increased in Baicalin-treated rats. In addition, the Toll Like Receptor 4 (TLR4)/ nuclear factor kappaB (NF-kappaB) pathway was enabled at 28 days after silica infusion, and the treatment of Baicalin diminished the expression of TLR4 and NF-?B in the lungs of rat with silicosis. These results suggested that Baicalin inhibited the pulmonary inflammatory and fibrosis in a rat model of silicosis, which could be attributed to inhibition of the TLR4/NF-kappaB pathway.

Comprehensive analysis of differences of N6-methyladenosine of lncRNAs between atrazine-induced and normal Xenopus laevis testis

Background

Increasing evidence suggested N⁶-methyladenosine (m⁶A) modification is crucial for male germline development. However, m⁶A modification of lncRNAs gains a little attention in amphibians in recent years. Xenopus laevis (X. laevis) was chosen to be an ideal model organism for testing environmental endocrine disrupting chemicals (EDCs) exposure and resultant effects. Atrazine (AZ) as an endocrine disrupt can effect development of testis in amphibians. Our previous study revealed that m⁶A is a highly conserved modification across the species.

Results

The results of m⁶A sequences showed that m⁶A-methylated lncRNAs enriched in intergenic region in testes of X. laevis. We further examined the differential expression of lncRNAs m⁶A sites in testes of AZ-exposed and compared with that in animals from control group. The results indicated that up to 198 differentially methylated m⁶A sites were detected within 188 lncRNAs, in which 89 significantly up-methylated sites and 109 significantly down-methylated sites. Data from KEGG pathway analysis indicated that AZ-affected lncRNAs m⁶A sites were mainly involved in 10 pathways in which 3 mutual pathways were found in the result of differentially m⁶A-methylated mRNAs.

Conclusions

These findings suggested that differentially m⁶A-methylated lncRNAs and these 3 pathways may act on regulatory roles in abnormal testis development of AZ-exposed X. laevis. This study for the first time provides insights into the profile of lncRNAs m⁶A modifications in amphibian species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41021-021-00223-0.

The role of HMGB1 on TDI-induced NLPR3 inflammasome activation via ROS/NF-κB pathway in HBE cells

To explore the potential role of HMGB1 on TDI-induced NLRP3 inflammasome activation, HBE cells were treated with TDI-HSA conjugate to observe the changes of HMGB1, TLR4, NF-κB, Nrf2 and NLRP3 inflammasome related proteins expressions, ROS release and MMP. NAC, TPCA-1 and Resatorvid pre-treatments were applied to explore the effects of ROS, NF-κB and TLR4 on TDI-induced NLRP3 inflammasome activation. The CRISPR/Cas9 system was used to construct HMGB1 gene knockout HBE cell line and then to explore the role of HMGB1 on TDI-HSA induced NLRP3 inflammasome activation. GL pre-treatment was applied to further confirm the role of HMGB1. Results showed that TDI increased HMGB1, TLR4, P-p65, Nrf2 proteins expressions and ROS release, decreased MMP level and activated NLRP3 inflammasome in HBE cells in a dose dependent manner. NAC, TPCA-1 and Resatorvid pre-treatments decreased the expression of P-p65 and inhibited NLRP3 inflammasome activation. Inhibition of HMGB1 decreased Nrf2 expression and ROS release, improved MMP level and reduced NLRP3 inflammasome activation. GL ameliorated NLRP3 inflammasome activation via inhibiting HMGB1 regulated ROS/NF-κB pathway. These results indicated that HMGB1 was involved in TDI-induced NLRP3 inflammasome activation as a positive regulatory mechanism. The study provided a potential target for early prevention and treatment of TDI-OA.

Dynamic assessing silica particle-induced pulmonary fibrosis and associated regulation of long non-coding RNA expression in Wistar rats

BACKGROUND

Exposure to respirable crystalline silica (RCS) can induce accelerated silicosis (AS), a form of silicosis that is more progressive and severe form of silicosis. In this project we aimed to assess processes of silicosis in rats exposed to RCS with focus on the regulation of long noncoding RNAs (lncRNAs).

RESULTS

The results showed that RCS induced acute inflammatory response as indicated by the appearance of inflammatory cells in the lung from the first day and peaked on day 7 of exposure. The fibroblasts appeared along with the inflammatory cells decreasing gradually on day 14. Extensive fibrosis appeared in the lung tissue, and silicon nodules were getting larger on day 28. Interestingly, the number of altered lncRNAs increased with the exposure time with 193, 424, 455, 421 and 682 lncRNAs on day 1, 7, 14, 21, and 28 after exposure, respectively. We obtained 285 lncRNAs with five significant temporal expression patterns whose expressions might correlate with severity of silicosis. KEGG analysis showed that lncRNAs from short time-series expression miner (STEM)-derived data mainly involved in 17 pathways such as complement and coagulation cascades.

CONCLUSIONS

The differential expression profiles of lncRNAs may be potential biomarkers in silicosis through modulating expressions of their relevant genes in lungs of rat and thus warrant further investigation.

Effects of chlorpyrifos exposure on liver inflammation and intestinal flora structure in mice

Chlorpyrifos (CPF) is an organophosphate insecticide commonly used to treat fruit and vegetable crops. CPF can cause severe adverse effects on body organs including the liver and central nervous system. This study investigated the CPF-induced inflammation in mice and explored the role of intestinal flora changes in liver inflammation. Adult C57BL/6 male mice were exposed to a CPF of 0.01-, 0.1-, 1- and 10-mg/kg bodyweight for 12 weeks. The mice in experimental group given CPF solution dissolved in corn oil vehicle by gavage, was administered by intraoral gavage for 5 days per week for 12 weeks. Histopathological examination and inflammatory factor detection were performed on mice liver tissue. Faeces were used for 16S ribosomal RNA high-throughput sequencing to explore the impact of CPF on intestinal flora structure and diversity. The results showed that 1- and 10-mg/kg CPF caused different degrees of liver focal inflammation. The structure of intestinal flora changed significantly in mice including the decreased beneficial bacteria (Akkermansia, Prevotella and Butyricimonas) and increased pathogenic bacteria (Helicobacter and Desulfovibrio). Meanwhile, the results of Q-RT-PCR showed that there was more total bacterial DNA in the liver tissue of the mice treated with 10-mg/kg groups. In conclusion, the imbalance of intestinal flora, the decreased abundance of beneficial bacteria and the increased abundance of pathogenic bacteria, as well as the increase of total bacterial DNA in the liver tissues, maybe associated with the liver focal inflammation induced by CPF.

Comparative proteomic analysis of silica-induced pulmonary fibrosis in rats based on tandem mass tag (TMT) quantitation technology

Silicosis is a systemic disease characterized by chronic persistent inflammation and incurable pulmonary fibrosis with the underlying molecular mechanisms to be fully elucidated. In this study, we employed tandem mass tag (TMT) based on quantitative proteomics technology to detect differentially expressed proteins (DEPs) in lung tissues of silica-exposed rats. A total of 285 DEPs (145 upregulated and 140 downregulated) were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the biological pathway and functional classification of the proteins. Results showed that these DEPs were mainly enriched in the phagosome, lysosome function, complement and the coagulation cascade, glutathione metabolism, focal adhesion and ECM-receptor interactions. To validate the proteomics data, we selected and analyzed the expression trends of six proteins including CD14, PSAP, GM2A, COL1A1, ITGA8 and CLDN5 using parallel reaction monitoring (PRM). The consistent result between PRM and TMT indicated the reliability of our proteomic data. These findings will help to reveal the pathogenesis of silicosis and provide potential therapeutic targets. Data are available via ProteomeXchange with identifier PXD020625.

Toluene diisocyanate-induced inflammation and airway remodeling involves autophagy in human bronchial epithelial cells

Toluene-diisocyanate (TDI) is one of the main causes of occupational asthma. To study the role of autophagy in TDI-induced airway inflammation and airway remodeling in bronchial airway epithelial (16HBE) cells. We treated 16HBE cells with TDI-human serum albumin (TDI-HSA) conjugate to observe reactive oxygen species (ROS) release, autophagy activation, airway inflammation and airway remodeling. 3-Methyladenine (3-MA) and Rapamycin (Rapa) intervention were used to explore the effects of autophagy on inflammatory response and protein expression related to airway remodeling in 16HBE cells treated with TDI-HSA. Experimental results suggested that various concentrations of TDI-HSA (0, 40, 80 and 120 μg/mL) increased the release of ROS and the expression of Nrf2, activated autophagy and increased the expression of AMPK, Beclin-1, LC3 and decreased the expression of p62, promoted the levels of IL-5, IL-6 and IL-8 in 16HBE cells. Results also showed that E-cadherin expression decreased but an increase was observed in α-SMA and MMP-9 in the TDI-HSA group. The treatment of TDI-HSA combined with Rapa aggravated the above reaction whereas the inverse was true for TDI-HSA combined with 3-MA. These results indicated that autophagy is involved in TDI-induced airway inflammation and airway remodeling as a positive regulatory mechanism, inhibiting autophagy can significantly alleviate the TDI-induced inflammatory response and attenuate airway remodeling protein expression in 16HBE cells.

Genome-wide analysis of DNA methylation in testis of male rat exposed to chlorpyrifos

In our previous study, we found that subchronic exposure of chlorpyrifos (CPF) can cause reproductive damage in male rats. However, the mechanisms underlying the reproductive effects of CPF are not well understood. DNA methylation is essential for epigenetic gene regulation in development and disease. Therefore, we aim to compare DNA methylation profiles between controls and CPF-treated rats in order to identify the epigenetic mechanism of male reproductive toxicity induced by CPF. Methylated DNA immunoprecipitation with high-throughput sequencing (MeDIP-seq) was used to investigate the genome-wide DNA methylation pattern in testes of control and CPF-treated rats for 90 days. We identified 27 019 differentially methylated regions (DMRs) (14 150 upmethylated and 12 869 downmethylated) between CPF-exposed and control groups. The DMR-related genes are mainly involved in 113 pathways predicted by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The result showed that high methylation gene PIK3CD may play a key role in epigenetic regulation of multiple pathways, such as Ras signaling pathway, AGE-RAGE signaling pathway in diabetic complications, HIF-1 signaling pathway, VEGF signaling pathway, and glioma and Fc epsilon RI signaling pathway in rats exposed to CPF. Our study provides significant explanations for the epigenetic mechanism of male reproductive toxicology induced by CPF.

Distinct m6A methylome profiles in poly(A) RNA from Xenopus laevis testis and that treated with atrazine

Recent discovery of reversible N⁶-methyladenosine (m⁶A) methylation on messenger RNA (mRNA) and mapping of m⁶A methylomes in mammals, plant and yeast revealed potential regulatory functions of this RNA modification. However, the role of the m⁶A methylomes in amphibious is still poorly understood. Here, we examined the m⁶A transcriptome-wide profile in testis tissues of Xenopus laevis (X. laevis) with and without treatment with 100 μg/L atrazine (AZ) through m⁶A sequencing analysis using the latest Illumina HiSeq sequencer. The results revealed that m⁶A is a highly conserved modification of mRNA in X. laevis. Distinct from that in mammals, m⁶A in X. laevisis enriched around the stop codon and start codon, as is reported in plant. We then investigated the differential expression m⁶A in testes of AZ-exposed X. laevis and compared that with the X. laevis in the control group by m⁶A sequencing. The results indicated that AZ leads to altered expression profile in 1380 m⁶A modification sites (696 upregulated and 684 downregulated). KEGG pathway analysis indicates that the "NOD-like receptors", "tight junction", "Peroxisome proliferator-activated receptors", "adherens junctions", "Glycerophospholipid metabolism" and "Fatty acid biosynthesis" signaling pathways may be associated with abnormal testis development of X. laevis due to exposure to AZ. Analysis results showed a positive correlation between m⁶A modification and mRNA abundance, suggesting a regulatory role of m⁶A in amphibious gene expression. Our first report of m⁶A transcriptome-wide map of an amphibian species X. laevis presented here provides a starting roadmap for uncovering m⁶A functions that may affect/control amphibian testis development.

Thymic stromal lymphopoietin (TSLP) and Toluene-diisocyanate-induced airway inflammation: Alleviation by TSLP neutralizing antibody

Toluene-diisocyanate (TDI) is mainly used in the manufacturing process of polyurethane foams, and is a potent inducer of occupational asthma characterized by airway inflammation and airway hyperreactivity. Thymic stromal lymphopoietin (TSLP) plays an important role in the development of asthma, and correlating with the differentiation of Th2 and Th17 cells. However, the role of TSLP in TDI-induced asthma remains unclear. In this study, 96 TDI-exposed workers as well as a mouse model of TDI-induced asthma were investigated. The air exposure assessment result of TDI in the workplace showed that workers were exposed to inhalation of a very high concentration of TDI, approximately 8 times the recommended level, leading to a decrease in pulmonary function and an increase in inflammatory cells, as well as TSLP and IgE levels in the supernatant of sputum obtained from exposed workers. In order to further investigate the role of TSLP in the pathogenesis of TDI-induced asthma, a mouse model of TDI-induced asthma was also employed. Histopathological analysis of mouse lung and bronchus showed an obvious infiltration of inflammatory cells around the bronchus. The levels of inflammatory cells, IFN-γ, IL-4 and IL-17 in bronchoalveolar lavage fluid (BALF), the expression levels of TSLP protein and ROR-γt and IL-17 mRNA in mouse lung tissues were also significantly increased. However, after treatment with TSLP neutralizing antibody (TSLP-Ab), the degree of pulmonary and bronchial inflammation in mice was significantly alleviated, and the levels of inflammatory cells, IFN-γ, IL-4 and IL-17 in BALF, and the expression levels of ROR-γt and IL-17 mRNA in lung tissue were significantly decreased. Our data shows that TSLP plays an important role in the pathogenesis of TDI-induced asthma, and that TSLP-Ab can effectively alleviate TDI-induced airway inflammation of asthma.

Mechanism of cell death induced by silica nanoparticles in hepatocyte cells is by apoptosis

Silicon is one of the most widely used chemical materials, and the increasing use of silica nanoparticles (SNs) highlights the requirement for safety and biological toxicity studies. The damaging and adverse effects of SNs on human hepatocytes remain largely unknown, as do the mechanisms involved. In the present study, the mechanisms underlying SN‑induced toxicity in the human hepatocyte cell line HL‑7702 were investigated. An MTT assay revealed that following exposure to SNs in the concentration range of 25‑200 µg/ml, the viability of HL‑7702 cells decreased, and the viability decreased further with increasing exposure time. SNs induced a delay in the S and G2/M phases of the cell cycle, and also induced DNA damage in these cells. Western blot and flow cytometry analyses revealed that cell death was mediated by mitochondrial damage and the upregulated expression of a number of pro‑apoptotic proteins. In conclusion, exposure to SNs led to mitochondrial and DNA damage, resulting in apoptosis‑mediated HL‑7702 cell death. The study provided evidence for the cellular toxicity of SNs, and added to the growing body of evidence regarding the potential damaging effects of nanoparticles, indicating that caution should be exercised in their widespread usage.

Profiling long non-coding RNA changes in silica-induced pulmonary fibrosis in rat

Silicosis is a kind of chronic and incurable lung fibrotic disease with pathogenesis and molecular mechanisms largely unknown. Mounting evidence suggests that long non-coding RNAs (lncRNAs) are involved in the pathogenesis of silicosis. However, how many lncRNAs involved in the pulmonary fibrosis remains to be elucidated. In this study, Wistar rats were exposed to silicon dioxide by an improved tracheal intubation method. Rats in the control group were treated with normal saline solution. Results showed that 28 days after exposure, there were significant differences in body weight and lung coefficient of rats treated with silica compared with control rats. The formation of lung fibrosis in silica-induced rats was confirmed by histologic examination. We then investigated the lncRNAs expression changes in lung tissues of silica-exposed rats and compared that with the rats in the control group using microarray. The results indicated that silica exposure leads to altered expression profile in 682 lncRNAs (300 upregulated and 382 downregulated). Seventy-three ceRNA pairs were acquired by predicted analysis. Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology analyses were used to predict the biological pathway and functional classification of lncRNAs. The results showed that silica exposure affected 13 lncRNAs pathways. The functional classification mainly involved in protein binding, cell shape and extracellular exosome. This study indicated that alteration of lncRNAs may play a role in silica-induced pulmonary fibrosis through regulation of expressions of functional genes in lungs of rat. Our results provide more insights into the mechanism of silicosis.

Analysis of long non-coding RNA involved in atrazine-induced testicular degeneration of Xenopus laevis

Long non-coding RNA (lncRNA) plays a critical role in male germline development. Atrazine (AZ) as an environmental endocrine disrupting chemical (EDCs) can induce male reproductive toxicity in amphibians. Our previous studies demonstrated that AZ can alter gene and circular RNA (circRNA) expression of damaged testes in Xenopus laevis (X. laevis). We furthered to investigate the lncRNA expression profiling in the testis of X. laevis. Over 3559 lncRNAs were detected by lncRNA sequencing. AZ induced 40 upregulated and 46 downregulated differentially expressed lncRNAs. KEGG analysis showed that AZ-affected lncRNAs mainly involve in 19 pathways among which 12 pathways are found in circRNA analysis. This study for the first time demonstrated that AZ can alter lncRNAs which may play a role in testicular degeneration through regulating expressions of functional genes in X. laevis. Our data may provide more insights on the mechanism about male reproductive toxicity of EDCs.

Validation and bioinformatics analysis of differentially expressed circRNAs involved in developing male Xenopus laevis chronically exposed to atrazine

The data presented here are related to the research article titled “Identification of circular RNAs and their alterations involved in developing male Xenopus laevis chronically exposed to atrazine” (Sai et al., 2018) [1]. Circular RNAs (circRNAs) are implicated in multiple developmental anomalies (Bachmayr-Heyda et al., 2015; Li et al., 2015) [2], [3]. This report describes the differentially expressed circRNAs involved in developing male Xenopus laevis (X. laevis) chronically exposed to atrazine (AZ) database. The database contains the validation of differentially expressed circRNAs, KEGG analysis of differentially expressed circRNA-associated target genes and prediction of miRNA binding sites. These data may help to further evaluate the role of circRNAs in male X. laevis chronically exposed to AZ.

Identification of circular RNAs and their alterations involved in developing male Xenopus laevis chronically exposed to atrazine

Atrazine (AZ) is an environmental endocrine disrupting chemical which can affect the development of amphibians. In our past studies, we demonstrated that chronical exposure to 100 μg/L AZ can cause abnormalities in development and related genes expression of gonads in developing male Xenopus laevis (X. laevis) tadpoles. Recent studies by others have demonstrated that circular RNAs (circRNAs) are implicated in multiple developmental anomalies. However, whether circRNAs involve in the effects in AZ-exposed X. laevis remains unknown. In this study, over 68575 circRNAs were detected by circRNA sequencing of testis tissues from control groups (n = 3) and AZ-treated X. laevis (n = 3). Treatment of AZ led to 405 circRNAs differentially expressed including 44 upregulated and 361 downregulated compared with froglets in the control groups. Two upregulated and 6 downregulated circRNAs were further validated by real-time PCR assay which displayed consistent regulation patterns as shown by the transcriptome sequencing results. Two hundreds and eighty two differentially expressed circRNAs played miRNA sponges roles. Kyoto Encyclopedia of Genes and Genomes pathway analysis of miRNA targets showed that AZ-affected circRNAs are mainly involved in 19 pathways. The Wnt signaling pathway and progesterone-mediated oocyte maturation pathway may be two involved signal pathways. This study for the first time provides evidence that AZ can alter circRNAs which play a role in AZ-induced testicular degeneration of developing male X. laevis through regulation of expressions of functional genes in the testes of X. laevis.

Continued Studies on the Effects of Simazine on the Liver Histological Structure and Metamorphosis in the Developing Xenopus laevis

This study continued our previous work (Sai et al. in Bull Environ Contam Toxicol 95:157-163, 2015a) by analysing the effects of simazine on the liver histological structure and metamorphosis in the developing Xenopus laevis. Tadpoles (Nieuwkoop-Faber stage 46) were exposed to simazine at 0.1, 1.2, 11.0 and 100.9 μg/L for 100 days. When tadpoles were exposed to simazine at 11.0 and 100.9 µg/L, an increased mortality and damaged liver tissues were observed together with significant inhibition of percent of X. laevis completing metamorphosis on days 80 and 90 and prolonged time of completing metamorphosis. On the other hand, we found that simazine has no significant effects on liver weight and altered hepatosomatic index. Results of this study may be considered to inform risk assessment of the effects of simazine on the development of X. laevis.

Gene expression profiles in testis of developing male Xenopus laevis damaged by chronic exposure of atrazine

As a widely used herbicide, atrazine (AZ) has been extensively studied for its adverse effects on the reproductive system, especially feminization in male animals. However, the relationship of gene expression changes and associated toxicological endpoints remains unclear. In this study, developing Xenopus laevis tadpoles were exposed to concentration of AZ at 0.1, 1, 10 or 100 μg/L continuously. Compared with froglets in the control group, there were no significant differences in body length, body weight, liver weight and hepatosomatic index (HSI) of males in groups treated with AZ for 90 d. At 100 μg/L AZ treatment caused a significant reduction of gonad weight and gonadosomatic index (GSI) of males (p < 0.01). In addition, AZ at all dose levels caused testicular degeneration, especially in froglets from the groups with 0.1 and 100 μg/L which exhibited U-shaped dose-response trend. We further investigated the gene expression changes associated with the testicular degeneration induced by AZ. We found that the expression of 1165 genes was significantly altered with 616 upregulated and 549 downregulated compared to the expression profile of the control animals. KEGG analysis showed that genes which were significantly affected by AZ are mainly involved in arginine and proline metabolism, cell cycle, riboflavin metabolism, spliceosome, base excision repair and progesterone-mediated oocyte maturation pathway. Our results show that AZ may affect reproductive and immune systems by interference with the related gene expression changes during the male X. laevis development. The findings may help to clarify the feminization mechanisms of AZ in male X. laevis.

Effects of α-zearalanol on spermatogenesis and sex hormone levels of male mice

AIMS

To investigate the mechanisms of α-zearalanol (Zeranol)-induced male reproductive toxicity, the effects of Zeranol on spermatogenesis and sex hormone levels of male mice were studied.

METHODS

Forty healthy sexually mature male Kunming mice were randomly divided into four groups. The mice were mock-treated or treated with Zeranol 25, 50 or 100 mg/kg via oral gavage for 35 days. The epididymal sperms were counted and their morphology and motility were analyzed. The testicles were examined by light and electron microscopy. The levels of serum/testicular testosterone (T), serum follicle stimulating hormone (FSH) and serum luteinizing hormone (LH) were determined by radioimmunoassay.

RESULTS

Zeranol decreased the epididymal sperm count and sperm motility in a dose depend manner. While there were not significant differences in the sperm malformation rates between the Zeranol treated groups and the control group. Furthermore, Zeranol could decrease the weight and the organ coefficient of the seminal vesicles and the testicles and lead to significant pathological changes of the testicles. Zeranol could also decrease the levels of serum T, FSH, LH as well as the levels of testicular T of male mice.

CONCLUSIONS

Zeranol induced reproductive toxicity in adult male mice. It could damage spermatogenesis via its direct effects on the testicles and interfere with sex hormone levels of male mice through its effects on the hypothalamic-pituitary-testicular axis.

The Effects of Simazine, a Chlorotriazine Herbicide, on the Expression of Genes in Developing Male Xenopus laevis

Simazine was investigated for gene expression concurrent with simazine-induced phenotype changes during development of male Xenopus laevis. X. laevis tadpoles (Nieuwkoop-Faber stage 46) were exposed to 0.1, 1.2, 11.0 and 100.9 μg/L simazine for 100 days. The results showed that an increased mortality of X. laevis, decreased gonad weight and altered gonadosomatic index of males significantly (p<0.05) when exposed to simazine at 11.0 and 100.9 µg/L. Significant degeneration in testicular tissues was observed when tadpoles were exposed to simazine at 100.9 µg/L. To investigate the molecular mechanisms behind the testicular degeneration by simazine, we evaluated gene expression in animals treated with 100.9 µg/L simazine and found that 1,315 genes were significantly altered (454 upregulated, 861 downregulated). Genes involved in the cell cycle control, and amino acid metabolism pathways were significantly downregulated. These results indicate that simazine affects the related gene expressions which may be helpful for the understanding of the reason for the reproductive toxicity of simazine on male X. laevis.

Assessing atrazine-induced toxicities in Bufo bufo gargarizans Cantor

Atrazine (AZ), a widely used herbicide has drawn attentions for its potential impacts on amphibians. This study aims to investigate the toxicity of AZ in Bufo bufo gargarizans Cantor (B. bufo gargarizans), a species of toad commonly found in China and countries in East Asia. We treated tadpoles with 0.1, 1, 10 and 100 μg/L AZ for 85 days and examined related parameters. The results showed that the mortality of the toads in the treatment group increased dramatically in a U-shaped dose-response relationship. The hindlimb extension and metamorphosis rate of the toads were significantly inhibited by AZ at 10 and 100 μg/L. Under the same condition, there were significant progressive changes in the testicular structures. Moreover, we found that AZ has no significant effects on growth, sex ratios, gonadal morphology, forelimb emergence and histology in the ovaries. Our results support the idea that environmental contaminants including AZ may be relevant to global amphibian decline.

Effects of chlorpyrifos on reproductive toxicology of male rats

The aim of this study is to investigate the effects of subchronic exposure to chlorpyrifos on reproductive toxicology of male rats. Forty healthy male rats were divided into four groups: three exposure groups and a control group. Chlorpyrifos was administered orally to male rats at 0, 2.7, 5.4, and 12.8 mg/kg for 90 days to evaluate the toxic alterations in testicular histology, testicular marker enzyme activities and related genes expression levels, sperm dynamics, and testosterone levels. The body weight and the testis weight of animals did not show any significant changes. Chlorpyrifos brought about marked reduction in testicular sperm counts, sperm motility, and significant growth of sperm malformation rate in exposed males. Histopathological examination of testes showed mild to severe degenerative changes in seminiferous tubules at various dose levels. The levels of testosterone (T) showed a decreasing tendency, and there was a statistical difference between the 5.4, 12.8 mg/kg groups, and the control group. The levels of follicle stimulating hormone (FSH) were significantly increased in 5.4 and 12.8 mg/kg groups, but there were no obvious effects on the levels of luteinizing hormone (LH) and estradiol (E2 ). A significant increase in the activities of LDH and LDH-x was observed in chlorpyrifos exposed rats in 5.4 and 12.8 mg/kg groups, but the expression levels of related genes had no significant differences between chlorpyrifos exposure groups and the control group. These results suggest that chlorpyrifos has adverse effects on reproductive system of male rats.