Impacts of co-exposure to zearalenone and trifloxystrobin on the enzymatic activity and gene expression in zebrafish.

Although humans and animals are usually exposed to combinations of toxic substances, little is known about the interactive toxicity of mycotoxins and farm chemicals. Therefore, we can not precisely evaluate the health risks of combined exposure. In the present work, using different approaches, we examined the toxic impacts of zearalenone and trifloxystrobin on zebrafish (Danio rerio). Our findings showed that the lethal toxicity of zearalenone to embryonic fish with a 10-day LC50 of 0.59 mg L-1 was lower than trifloxystrobin (0.037 mg L-1). Besides, the mixture of zearalenone and trifloxystrobin triggered acute synergetic toxicity to embryonic fish. Moreover, the contents of CAT, CYP450, and VTG were distinctly altered in most single and combined exposures. Transcriptional levels of 23 genes involved in the oxidative response, apoptosis, immune, and endocrine systems were determined. Our results implied that eight genes (cas9, apaf-1, bcl-2, il-8, trb, vtg1, erß1, and tg) displayed greater changes when exposed to the mixture of zearalenone and trifloxystrobin compared with the corresponding individual chemicals. Our findings indicated that performing the risk assessment based on the combined impact rather than the individual dosage response of these chemicals was more accurate. Nevertheless, further investigations are still necessary to reveal the modes of action of mycotoxin and pesticide combinations and alleviate their effects on human health.

Reference genes for the study of herbicide stress responses in Leptochloa chinensis (L.) Nees and estimation of ACCase expression in cyhalofop-butyl resistant populations.

Cyhalofop-butyl resistance in Leptochloa chinensis (L.) Nees is a threat to rice production. Qualitative changes to the acetyl-CoA carboxylase gene (ACCase) have been reported to induce cyhalofop-butyl resistance in some weed species, but the role of ACCase in cyhalofop-butyl resistance through quantitative changes remains uncertain. The accurate assessment of transcriptional changes in the functional genes associated with herbicide resistance in L. chinensis is challenging owing to the lack of available reference genes for expression normalization. Here, we selected nine candidate reference genes in L. chinensis and assessed their transcription stability in populations susceptible and resistant to cyhalofop-butyl. Transcription stability was compared under conditions of herbicide stress and control conditions using BestKeeper, NormFinder, and geNorm. Elongation factor 1 alpha, eukaryotic initiation factor 4A, and cap-binding protein CBP20 were the most stable reference genes under cyhalofop-butyl treatment. Transcription levels of ACCase were evaluated in seven resistant populations, one of which showed higher transcription than the susceptible population after 24 h cyhalofop-butyl treatment. However, the slight up-regulation of ACCase (approximately 2.0-fold) is unlikely to be responsible for the high resistance levels in these populations of L. chinensis.

Assessment of Carbendazim Residues and Safety in Celery Under Different Cultivation Conditions.

Although the carbendazim is widely used to manage spot blight in celery cultivation, information on residues identified is of interest. In this study, we examined the dissipation and residual amounts of carbendazim in celery and soil under different cultivation methods when using the suggested dose and ten times of that and the bioconcentration factor of carbendazim for celery. The results showed that when celery leaves were sprayed with the suggested dose, the half-lives in a celery field and greenhouse were 2.75 days and 3.29 days, respectively. When the soil matrix was sprayed with the recommended dose before cultivation, the half-lives of carbendazim residues were 16.86 days and 11.97 days. We also conducted a long-term dietary risk assessment using the corresponding criteria. The results showed that, in China, the use of carbendazim at a dose of 0.022 g/m2 is safer and more reasonable when the harvest interval is 28 days.

Embryonic exposure to carbendazim induces the transcription of genes related to apoptosis, immunotoxicity and endocrine disruption in zebrafish (Danio rerio).

Carbendazim is one of the most widespread environmental contaminant that can cause major concern to human and animal reproductive system. To date, very few studies have been conducted on the toxic effect of carbendazim in the non-target organism zebrafish (Danio rerio). The study presented here aimed to assess how carbendazim triggers apoptosis, immunotoxicity and endocrine disruption pathways in zebrafish during its embryo development. Our results demonstrated that the expression patterns of many key genes involved in cell apoptosis pathway (e.g. P53, Mdm2, Bbc3 and Cas8) were significantly up-regulated upon the exposure to carbendazim at the concentration of 500 µg/L, while the Bcl2 and Cas3 were down-regulated at the same concentration, interestingly, the expression level of Ogg1 decreased at all the exposure concentrations. It was also observed that the mRNA levels of CXCL-C1C, CCL1, IL-1b and TNFα which were closely related to the innate immune system, were affected in newly hatched zebrafish after exposed to different concentrations of carbendazim. Moreover, the expression of genes that are involved in the hypothalamic-pituitary-gonadal/thyroid (HPG/HPT) axis including VTG, ERα, ERß2, Dio1, Dio2, Thraa and Thrb were all down-regulated significantly after the exposure to carbendazim. The expression levels of two cytochrome P450 aromatases CYP19a and CYP19b were increased significantly after 20 and 100 µg/L carbendazim exposure, respectively. Taken together, our results indicated that carbendazim had the potential to induce cell apoptosis and cause immune toxicity as well as endocrine disruption in zebrafish during the embryo developmental stage. The information presented here also help to elucidate the environmental risks caused by the carbendazim-induced toxicity in aquatic organisms.

Combined toxicity of abamectin and carbendazim on enzymatic and transcriptional levels in the soil-earthworm microcosm.

To reveal the toxicological mechanisms of pesticide mixtures on soil organisms, this study concentrated on evaluating enzymatic activity and gene expression changes in the earthworm Eisenia fetida (Savigny 1826). Despite being frequently exposed to multiple pesticides, including the common combination of abamectin (ABA) and carbendazim (CAR), environmental organisms have primarily been studied for the effects of individual pesticides. Acute toxicity results exhibited that the combination of ABA and CAR caused a synergistic impact on E. fetida. The levels of MDA, ROS, T-SOD, and caspase3 demonstrated a significant increase across most individual and combined groups, indicating the induction of oxidative stress and cell death. Additionally, the expression of three genes (hsp70, gst, and crt) exhibited a significant decrease following exposure to individual pesticides and their combinations, pointing toward cellular damage and impaired detoxification function. In contrast, a noteworthy increase in ann expression was observed after exposure to both individual pesticides and their mixtures, suggesting the stimulation of reproductive capacity in E. fetida. The present findings contributed to a more comprehensive understanding of the potential toxicity mechanisms of the ABA and CAR mixture, specifically on oxidative stress, cell death, detoxification dysfunction, and reproductive capacity in earthworms. Collectively, these data offered valuable toxicological insights into the combined effects of pesticides on soil organisms, enhancing our understanding of the underlying risks associated with the coexistence of different pesticides in natural soil environments.

Enantioselective degradation of tebuconazole in cabbage, cucumber, and soils.

The enantioselective degradation of tebuconazole has been investigated to elucidate the behaviors in agricultural soils, cabbage, and cucumber fruit. Rac-tebuconazole was fortified into three types of agricultural soils and sprayed foliage of cabbage and cucumber, respectively. The degradation kinetics, enantiomer fraction and enantiomeric selectivity were determined by reverse-phase high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) on a Lux amylose-2 chiral column. The process of the degradation of tebuconazole enantiomers followed first-order kinetic in the test soils and vegetables. It has been shown that the degradation of tebuconazole was enantioselective. The results indicated that the (+)-S-tebuconazole showed a faster degradation in cabbage, while the (-)-R-tebuconazole dissipated faster than (+)-S-form in cucumber fruit and the test soils.

Comparative acute toxicity of twenty-four insecticides to earthworm, Eisenia fetida.

In this study, we used two different types of bioassay, a contact filter paper toxicity bioassay and a soil toxicity bioassay, to compare the acute toxicity of twenty-four insecticides belonging to six chemical categories on earthworm species, Eisenia fetida. Results of the contact filter paper toxicity bioassay indicated that neonicotinoids were super toxic to E. fetida (48 h-LC(50) value ranged from 0.0088 to 0.45 µg cm(-2)), pyrethroids were very toxic (48 h-LC(50) values ranged from 10.55 to 25.7 µg cm(-2)) and insect growth regulators (IGRs) were moderately toxic (48 h-LC(50) values ranged from 117.6 to 564.6 µg cm(-2)) to the worms. However, antibiotics, carbamates and organophosphates induced variable toxicity responses in E. fetida, and were very to extremely toxic (48 h-LC(50) values ranged from 3.64 to 75.75 µg cm(-2)). Results of the soil toxicity bioassays showed a different pattern of toxicity except that neonicotinoids were the most toxic even under the soil toxicity bioassay system. The acute toxicity of neonicotinoids was higher than those of antibiotics, carbamates, IGRs and organophosphates. In contrast, pyrethroids were the least toxic to the worms under the soil toxicity bioassay system. It was concluded that irrespective of bioassay systems, earthworms were more susceptible to neonicotinoids than other modern synthetic insecticides.

Assessment of toxicity risk of insecticides used in rice ecosystem on Trichogramma japonicum, an egg parasitoid of rice lepidopterans.

Both chemical and biological methods are essential for control of insects, for example, lepidopterans, on rice. Thus, it is important to know the effect of chemicals on the biological control agents. In this study, we assessed the toxicity of commonly used insecticides on a biological control agent, Trichogramma japonicum Ahmead (an egg parasitoid of rice lepidopterans) by using a dry film residue method. Results showed that thirty insecticides from seven chemical classes exhibited various degree of toxicity to this parasitoid. Among the seven classes of chemicals tested, organophosphates (chlorpyrifos, fenitrothion, phoxim, profenofos, and triazophos) and carbamates (carbaryl, carbsulfan, isoprocarb, metolcarb, and promecarb) exhibited the highest intrinsic toxicity to T. japponicum, with an LC50 of 0.035 (0.029-0.044) to 0.49 (0.34-0.87) mg active ingredient (a.i.) L(-1), followed by antibiotics (abamectin, emamectin benzoate, and ivermectin), phenylpyrazoles (butane-fipronil, ethiprole, and fipronil), pyrethroids (cyhalthrin, cypermethrin, fenpropathrin, and lambda-cyhaothrin), and neonicotinoids (acetamiprid, imidacloprid, imidaclothiz, nitenpyram, thiacloprid, and thiamethoxam). Moreover, the insect growth regulator insecticides (chlorfluazuron, fufenozide, hexaflumuron and tebufenozide) exhibited the lowest toxicity to the wasps with an LC50 of 3,383 (2406-5499) to 30206 (23107-41008) mg ai. L(-1). Risk quotient analysis showed that phenylpyrazoles, pyrethroids, insect growth regulators, neonicotinoids (with the exception of thiamethoxam), and antibiotics (with the exception of abamectin) are classified as safe agents to the parasitoid, while organophosphates and carbamates are classified as slightly, moderately, or highly toxic agents to the parasitoid. The data presented in this paper provided useful information on the selection of compatible insecticides with T. japonicum.

Diverse mechanisms associated with cyhalofop-butyl resistance in Chinese sprangletop (Leptochloa chinensis (L.) Nees): Characterization of target-site mutations and metabolic resistance-related genes in two resistant populations.

Resistance of Chinese sprangletop (Leptochloa chinensis (L.) Nees) to the herbicide cyhalofop-butyl has recently become a severe problem in rice cultivation. However, the molecular mechanisms of target-site resistance (TSR) in cyhalofop-butyl-resistant L. chinensis as well as the underlying non-target-site resistance (NTSR) have not yet been well-characterized. This study aimed to investigate cyhalofop-butyl resistance mechanisms using one susceptible population (LC-S) and two resistant populations (LC-1701 and LC-1704) of L. chinensis. We analyzed two gene copies encoding the entire carboxyltransferase (CT) domain of chloroplastic acetyl-CoA carboxylase (ACCase) from each population. Two non-synonymous substitutions were detected in the resistant L. chinensis populations (Trp2027-Cys in the ACCase1 of LC-1701 and Leu1818-Phe in the ACCase2 of LC-1704), which were absent in LC-S. As Trp2027-Cys confers resistance to ACCase-inhibiting herbicides, the potential relationship between the novel Leu1818-Phe mutation and cyhalofop-butyl resistance in LC-1704 was further explored by single-nucleotide polymorphism (SNP) detection. Metabolic inhibition assays indicated that cytochrome P450 monooxygenases (P450s) and glutathione S-transferases (GSTs) contributed to cyhalofop-butyl resistance in specific resistant populations. RNA sequencing showed that the P450 genes CYP71Z18, CYP71C4, CYP71C1, CYP81Q32, and CYP76B6 and the GST genes GSTF11, GSTF1, and GSTU6 were upregulated in at least one resistant population, which indicated their putative roles in cyhalofop-butyl resistance of L. chinensis. Correlation analyses revealed that the constitutive or inducible expression patterns of CYP71C4, CYP71C1, GSTF1, and GSTU6 in L. chinensis were strongly associated with the resistant phenotype. For this reason, attention should be directed towards these genes to elucidate metabolic resistance to cyhalofop-butyl in L. chinensis. The findings of this study improve the understanding of mechanisms responsible for resistance to ACCase-inhibiting herbicides in grass-weed species at the molecular level, thus aiding in the development of weed management strategies that delay the emergence of resistance to this class of pest control products.

Carbendazim has the potential to induce oxidative stress, apoptosis, immunotoxicity and endocrine disruption during zebrafish larvae development.

Increasing evidence have suggested deleterious effects of carbendazim on reproduction, apoptosis, immunotoxicity and endocrine disruption in mice and rats, however, the developmental toxicity of carbendazim to aquatic organisms remains obscure. In the present study, we utilized zebrafish as an environmental monitoring model to characterize the effects of carbendazim on expression of genes related to oxidative stress, apoptosis, immunotoxicity and endocrine disruption during larval development. Different trends in gene expression were observed upon exposing the larvae to 4, 20, 100, and 500 µg/L carbendazim for 4 and 8d. The mRNA levels of catalase, glutathione peroxidase and manganese superoxide dismutase (CAT, GPX, and Mn/SOD) were up-regulated after exposure to different concentrations of carbendazim for 4 or 8d. The up-regulation of p53, Apaf1, Cas8 and the down-regulation of Bcl2, Mdm2, Cas3 in the apoptosis pathway, as well as the increased expression of cytokines and chemokines, including CXCL-C1C, CCL1, IL-1b, IFN, IL-8, and TNFα, suggested carbendazim might trigger apoptosis and immune response during zebrafish larval development. In addition, the alteration of mRNA expression of VTG, ERα, ERß1, ERß2, TRα, TRß, Dio1, and Dio2 indicated the potential of carbendazim to induce endocrine disruption in zebrafish larvae. These data suggested that carbendazim could simultaneously induce multiple responses during zebrafish larval development, and bidirectional interactions among oxidative stress, apoptosis pathway, immune and endocrine systems might be present.

Toxicity risk of insecticides to the insect egg parasitoid Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae).

BACKGROUND: Natural populations of Trichogramma evanescens contribute to the control of lepidopterous pests. The toxic effects of insecticides have been extensively reported on trichogrammatids, but are largely unknown on T. evanescens. In this study, the toxicities of seven classes of chemicals against the parasitoid were investigated. RESULTS: Among these classes, organophosphates and carbamates exhibited the highest levels of intrinsic toxicity, with LC50 values ranging from 0.025 (0.023-0.028) to 2.20 (1.71-3.09) and from 0.040 (0.032-0.053) to 1.84 (1.53-2.30) mg AI L(-1) respectively. Among the phenylpyrazoles, only ethiprole can be considered to be less toxic in the group. Avermectins, pyrethroids and neonicotinoids were less toxic, with LC50 values ranging from 1.29 to 2.57, from 2.26 to 14.03 and from 1.12 to 239.1 mg AI L(-1) respectively. In contrast, insect growth regulators (IGRs) showed the lowest toxicity to the parasitoid, with LC50 values ranging from 3383 (2406-5499) to 5650 (4228-8579) mg AI L(-1) . CONCLUSION: The results of risk quotient analysis indicated that neonicotinoids, avermectins, pyrethroids and IGRs were less hazardous, but phenylpyrazoles (except for ethiprole), organophosphates and carbamates were slightly to moderately or dangerously toxic to T. evanescens. The present results provide informative data for implementing biological and chemical control strategies in integrated pest management of lepidopterans.

Identification and mRNA expression profile of glutamate receptor-like gene in quinclorac-resistant and susceptible Echinochloa crus-galli.

Animal ionotropic glutamate receptors (iGluRs) function as Ca(2+) ion channels during excitatory neurotransmission in nerve cells. Here, a glutamate receptor-like gene (GLR) was identified and characterized from a plant - Echinochloa crus-galli. The GLR gene was designated EcGLR1 with GenBank no: JX518597. It has a 2,793 bp open reading frame predicted to encode a 101.7 kDa protein. Sequence alignment showed that EcGLR1 is a GLR homologue. Its expression in response to quinclorac treatment was assessed by real-time PCR in near-isogenic lines of quinclorac-resistant (R) and susceptible (S) biotypes of E. crus-galli. The expression of EcGLR1 in the seedling leaf and root at least increased 5 times in the S plants and 22 times in the R plants after exposure to quinclorac. In the adult plant leaves, roots and stems, its expression increased 11-14 times in the S plants and 23-25 times in the R plants after quinclorac stimulation. In the seed, its expression was 4 times less in the S plants than that in the R plants, but after treatment, the levels all increased by about 24 times in the two biotypes. EcGLR1 expression was 1-4 times greater in the R plants than in that in the S plants, and after treatment by quinclorac, the difference increased to a ratio of 4 to 9. Its expression was higher in all tissues tested of R biotypes than in that of S plants before or after quinclorac treatment. The results of this study provide basic information for the further research of function of the EcGLR1 in resistance to quinclorac in E. crus-galli.

Toxicity assessment of 45 pesticides to the epigeic earthworm Eisenia fetida.

This study was conducted to investigate comparative toxicity of 45 pesticides, including insecticides, acaricides, fungicides, and herbicides, toward the epigeic earthworm Eisenia fetida. Results from a 48-h filter paper contact test indicated that clothianidin, fenpyroximate, and pyridaben were supertoxic to E. fetida with LC(50) values ranging from 0.28 (0.24-0.35) to 0.72 (0.60-0.94) µg cm(-2), followed by carbaryl, pyridaphenthion, azoxystrobin, cyproconazole, and picoxystrobin with LC(50) values ranging from 2.72 (2.22-0.3.19) to 8.48 (7.38-10.21) µg cm(-2), while the other pesticides ranged from being relatively nontoxic to very toxic to the worms. When tested in artificial soil for 14 d, clothianidin and picoxystrobin showed the highest intrinsic toxicity against E. fetida, and their LC(50) values were 6.06 (5.60-6.77) and 7.22 (5.29-8.68) mg kg(-1), respectively, followed by fenpyroximate with an LC(50) of 75.52 (68.21-86.57) mgkg(-1). However, the herbicides fluoroglycofen, paraquat, and pyraflufen-ethyl exhibited the lowest toxicities with LC(50) values>1000 mg kg(-1). In contrast, the other pesticides exhibited relatively low toxicities with LC(50) values ranging from 133.5 (124.5-150.5) to 895.2 (754.2-1198.0) mg kg(-1). The data presented in this paper provided useful information for evaluating the potential risk of these chemicals to soil invertebrates.

Insecticide toxic effects on Trichogramma ostriniae (Hymenoptera: Trichogrammatidae).

BACKGROUND: The parasitoid Trichogramma ostriniae (Pang and Chen) is a major natural enemy of many lepidopterans, but only a few studies have been conducted on the compatibility of biological and chemical controls. In this study, the selectivity of 30 insecticides to T. ostriniae adults was evaluated. RESULTS: Among the seven classes of chemicals tested, organophosphates and carbamates had the highest intrinsic toxicity to the wasp, with LC(50) values ranging from 0.032 (0.029-0.038) to 2.38 (1.91-3.15) mg AI L(-1). They are followed by phenylpyrazoles, avermectins, neonicotinoids and pyrethroids, which induce variable toxicity responses, with LC(50) values ranging from 0.14 (0.11-0.21) to 56.67 (48.94-67.24) mg AI L(-1), from 2.57 (1.85-4.28) to 4.48 (3.34-6.83) mg AI L(-1), from 2.48 (1.80-4.03) to 503.6 (457.6-557.5) mg AI L(-1) and from 5.44 (3.95-8.84) to 104.2 (92.48-119.7) mg AI L(-1) respectively. The insect growth regulators (IGRs) exhibited least toxicity to the parasitoid. CONCLUSION: Risk quotient analysis classifies neonicotinoids, avermectins, pyrethroids, IGRs and phenylpyrazoles (with the exception of butane-fipronil and fipronil) as safe agents to the parasitoid, but categorises organophosphates and carbamates as slightly to moderately toxic or dangerous to T. ostriniae.

Enantioselective residue dissipation of hexaconazole in cucumber (Cucumis sativus L.), head cabbage (Brassica oleracea L. var. caulorapa DC.), and soils.

In this study, the enantioselective dissipation behavior of hexaconazole was investigated in cucumber fruit, head cabbage, and two different types of agricultural soils. The dissipation kinetics was determined by reverse-phase liquid chromatography-tandem mass spectrometry on a cellulose tris (3-chloro-4-methylphenylcarbamate) chiral column. Dissipation rates of hexaconazole enantiomers followed first-order kinetics; the residues of (+)-enantiomer decreased more rapidly than (-)-enantiomer in cucumber and head cabbage, resulting in relative enrichment of the (-)-form, while the two enantiomers showed similar degradation rates in the tested soils. These results indicate substantial enantioselectivity in the residue dissipation of hexaconazole enantiomers in cucumber and head cabbage; however, nonenantioselective dissipation was observed in the tested soils.

Complete sequence of the yak (Bos grunniens) mitochondrial genome and its evolutionary relationship with other ruminants.

The yak (Bos grunniens) is the most important domesticated species in the Qinhai-Tibetan Plateau. In present study, the complete sequence of the yak mitochondrial genome was determined. Sequence analysis revealed that there are no differences with cattle in the yak mitochondrial genome organization. Interestingly, within the D-loop, the conserved sequence blocks are less conserved than surrounding regions. Neighbor-Joining (NJ) trees based on single genes, gene sets and concatenated genes of mitochondrial genome were constructed. The analysis identified the yak as a sister group of a cattle/zebu clade. Based on substitutions in 22 tRNA genes, 12S rRNA gene and 16S rRNA gene, the dating of divergence between yak and cattle/zebu, and yak and water buffalo, was proposed to have occurred 4.38-5.32 and 10.54-13.85 million years before present, respectively. This is consistent with the paleontologyical data. Yak and sheep/goat divergent dating predicts that their divergence occurred at 13.14-27.99 million years before the present day.

[Effects of Chinese herbal medicine for supplementing Shen and strengthening the bone on rat distal femur cancellous bone in simulated weightlessness: an observation with scanning electron microscope].

OBJECTIVE: To observe the effect of Chinese herbal medicine for supplementing Shen and strengthening the bone on distal femoral trabecular ultrastructure of male rats subjected to simulated weightlessness. METHODS: Fifteen male SD rats were randomized equally into 3 groups, including a control group (group A, in which the rats were allowed free movement) and two simulated weightlessness (via tail suspension) groups (group B and C). The rats in group C were treated with the commercially available Chinese herbal preparation, and those in the other two groups received normal saline at the same dose, for a treatment course of 28 days. Observation of trabeculae was performed with scanning electron microscopy. RESULTS: In group B, the trabeculae of the femur became thinner, fragile, discontinuous with reduced quantity as compared with those in group A. The rats in group C had greater number of the trabeculae than those in group B. Resorption surface decreased and the collagenous fiber were much more regular in group B. CONCLUSION: The Chinese herbal medicine may produce beneficial effect on bone microstructure of rats subjected to simulated weightlessness.