Abnormal fertilization is responsible for reduced fecundity following thiram-induced ovulatory delay in the rat

Molecular mechanism of thiram-induced abnormal chondrocyte proliferation via lncRNA MSTRG.74.1-BNIP3 axis

Thiram, a widely used organic pesticide in agriculture, exhibits both bactericidal and insecticidal effects. However, prolonged exposure to thiram has been linked to bone deformities and cartilage damage, contributing to the development of tibial dyschondroplasia (TD) in broilers and posing a significant threat to global agricultural production. TD, a prevalent nutritional metabolic disease, manifests as clinical symptoms like unstable standing, claudication, and sluggish movement in affected broilers. In recent years, there has been growing recognition of the regulatory role of long non-coding RNA (lncRNA) in tibial cartilage formation among broilers through diverse signaling pathways. This study employs in vitro experimental models, growth performance analysis, and clinical observation to assess broilers' susceptibility to thiram pollution. Transcriptome sequencing analysis revealed a significant elevation in the expression of lncRNA MSTRG.74.1 in both the con group and the thiram-induced in vitro group. The results showed that lncRNA MSTRG.74.1 plays a pivotal role in influencing the proliferation and abnormal differentiation of chondrocytes. This regulation occurs through the negative modulation of apoptotic genes, including Bax, Cytc, Bcl2, Apaf1, and Caspase3, along with genes Atg5, Beclin1, LC3b, and protein p62. Moreover, the overexpression of lncRNA MSTRG.74.1 was found to regulate broiler chondrocyte development by upregulating BNIP3. In summary, this research sheds light on thiram-induced abnormal chondrocyte proliferation in TD broilers, emphasizing the significant regulatory role of the lncRNA MSTRG.74.1-BNIP3 axis, which will contribute to our understanding of the molecular mechanisms underlying TD development in broilers exposed to thiram.

Thiram exposure in environment: A critical review on cytotoxicity

Thiram is used in large quantities in agriculture and may contaminate the environment by improper handling or storage in chemical plants and warehouses. A review of the literature has shown that thiram can affect different organs in animals and its toxic mechanisms can be elucidated in more detail at molecular level. We have summarized several impacts of thiram on animals: the effects of the perspectives of oxidative stress, mitochondrial damage, autophagy, apoptosis, and the IHH/PTHrP pathway on regulating abnormal skeletal development in particular tibial dyschondroplasia and kyphosis; angiogenesis inhibition was investigated from the perspective of angiogenesis factor inhibition, PI3K/AKT signaling pathway and CD147; the inhibition effect of thiram on fibroblasts and erythrocytes via the perspective of oxidative stress, mitochondrial damage and inhibition of growth factors in animal skin fibroblasts and erythrocytes; studied fertilized egg size, reduced fertility, neurodegeneration, and immune damage from the perspectives of CYP51 inhibition and dopamine-b-hydroxylase inhibition in the reproductive system, vitamin D deficiency in the nervous system, and inflammatory damage in the immune system; embryonic dysplasia in terms of thyroid hormone repression in animal embryonic development and repression of the SOX9a transcription factor. The elucidation of the mechanisms of toxicity of thiram on various organs of animals at molecular level will enable a more detailed understanding of the mechanisms of toxicity of thiram in animals and will facilitate the exploration of the treatment of thiram poisoning at molecular level.

Mancozeb exposure during development and lactation periods results in decreased oocyte maturation, fertilization rates, and implantation in the first-generation mice pups: Protective effect of vitamins E and C

This study aimed to evaluate the mancozeb (MNZ) impact on oocyte maturation of first-generation mice pups as well as their fertilization rate, embryo development, and implantation along with the preventative effect of vitamins E and C. Pregnant mice were randomly divided into six groups: control, vehicle, and MNZ (500 mg/kg body weight (BW)), vitamin E (200 mg/kg BW), MNZ plus vitamin E, MNZ plus vitamin C (100 mg/kg BW), and MNZ plus two vitamins. All treatments were conducted by oral gavage every 2 days from the second day of gestation until the end of lactation. Vitamin treatment was initiated 30 min before receiving MNZ. After birth, first-generation mice pups were kept until adulthood (8-10 W). Adult female mice pups superovulated and then the collected oocytes were examined for nuclear maturity status. After in vitro fertilization of metaphase II oocytes with sperm of the first-generation male mice pups, fertilization rate and embryo development were evaluated over 24 h. Also, the fecundity rate and the number of implanted embryos in vivo were studied on the eighth day of pregnancy. MNZ exposure during embryo development and lactation significantly decreased the total number of collected oocytes, oocyte maturation, fertilization rate, implantation rate, fecundity rate, and embryo development compared with the control group in the first-generation pups. In contrast, vitamin treatments significantly increased these parameters compared to the MNZ group. Reduction in the quality of oocyte, the rate of fertilization, embryo implantation, and development following MNZ exposure could decrease female reproductive success, while coadministration of vitamins E and C could prevent these complications.

A rapid and efficient method for the collection of highly developmental murine immature oocytes using cilostazol, a phosphodiesterase 3A inhibitor

AIMS

The present study aims to define maturation, yield, health, and ease of collection of murine immature oocytes recovered using the conventional method or from mice treated with cilostazol.

MAIN METHODS

The conventional method included the superovulation of mice and the recovery of germinal vesicle (GV) or metaphase (MI) oocytes from preovulatory follicles. The cilostazol method included the oral treatment of superovulated mice with 7.5 mg cilostazol once or twice to result in the ovulation of MI or GV oocytes, respectively.

KEY FINDINGS

The cilostazol method resulted in >95% of GV or MI oocytes with a diameter range of 60-90 μm or 50.1-70 μm in comparison to <60.0% of GV or MI oocytes resulting from the conventional method, respectively (P < 0.0001). The cilostazol method resulted in GV oocytes having higher levels of co-occurrence of peripheral cortical granules (CG) and chromatin configuration of surrounded nucleolus and MI oocytes having higher levels of co-occurrence of normally organized spindles/chromosomes and peripheral CG with free domains than did the conventional method (P < 0.001). The cilostazol method was more time and labor efficient and resulted in higher oocyte yields of normal morphology than did the conventional method (P < 0.01).

SIGNIFICANCE

The presented method provides not only oocytes with uniform size and synchronized developmental maturation but also a technique of oocyte collection that is efficient and resourceful. It is possible that not all immature oocytes resulting from the conventional method are from preovulatory follicles nor have been developed adequately and consequently ovulated as opposed to the presented method.

The protective effects of silybin on the cytotoxicity of thiram in human, rat and chicken cell cultures

The study objective was a determination of thiram cytotoxicity and silybin cytoprotective activity in course of the fungicide impact on cell metabolism and membrane integrity. Firstly, human, rat, chicken hepatoma cells and rat myoblasts cultures were incubated with thiram. The results showed higher sensitivity of myoblasts on thiram exposure than the hepatoma cells. Among hepatoma cells, the chicken cultures were the most sensitive on the fungicide endangering. The mitochondrial activity was the most thiram affected function within all types the cell lines used. When silybin co-acted with thiram, an increase of the cell viability was recorded. The EC₅₀-values were higher for thiram subjected to interaction with silybin than the effect of alone thiram action. The interaction mode between the studied compounds shown by combination index (CI) represented an antagonistic or an additive nature and was depended on thiram concentration, type of the cells and the assay used. Moreover, the morphology changes were dependent on silybin presence in the cell cultures subjected to thiram impact at the same time. Staining with Hoechst 33342 and propidium ioidium revealed the apoptosis cell death in the incubation cultures. Definitely, the results have shown a potential of silybin to protect the cultured cells in course of cytotoxicity induced by thiram. However, future studies taking into account other endpoints of thiram cytotoxicity pathways including species differences and the cytoprotection efficacy could be of interest.

Quantification of oocyte-specific transcripts in follicle-enclosed oocytes during antral development and maturation in vitro

Oocyte cytoplasmic maturation is influenced by the quantity of synthesized RNA and proteins accumulated and stored during growth. Transcriptional repression and degradation of transcripts occur during oocyte nuclear maturation, and prolonged transcriptional arrest might compromise RNA stores for early development. RNA quantification of key genes in oocytes might be valuable when setting up in vitro cultures that lack the normal hormonal interplay found in vivo. This study quantifies gene expression levels in relation to follicle culture time and time of oocyte maturation in a mouse model. RNA levels of Gdf-9, Bmp-15, Mater, Zar-1, Npm-2 and Fgf-8 were measured in germinal vesicle oocytes along fixed times during in vitro follicle development. For all genes, the highest mRNA levels were detected in oocytes in the pre-antral follicle stage. Antrum formation was associated with a progressive shutdown in transcription leading to mRNA values lower than those in vivo preovulatory oocytes by extending period of in vitro culture. In contrast to in vitro-matured oocytes, the in vivo oocytes from 22- and 29-day-old prepubertal animals obtained after pregnant mare's serum gonadotrophin and human chorionic gonadotrophin priming did not down-regulate transcripts upon maturation stimulus except for Mater. These findings show that oocyte gene expression patterns under in vitro conditions can, at certain times, mimic what is reported to occur under in vivo conditions. Moreover, they also show that meiotically competent oocytes kept in a prolonged transcriptionally inactive stage express altered levels of key transcripts compared with in vivo in both immature and mature oocytes.

Nitric oxide extends the oocyte temporal window for optimal fertilization

Deteriorating oocyte quality is a critical hurdle in the management of infertility, especially one associated with advancing age. In this study, we explore the role of nitric oxide (NO) on the sustenance of oocyte quality postovulation. Sibling oocytes from superovulated mice were subjected to intracytoplasmic sperm injection (ICSI) with cauda-epididymal spermatozoa following exposure to either the NO donor, S-nitroso-N-acetylpenicillamine (SNAP, 0.23 microM/min), an NO synthase (NOS) inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 1 mM), or an inhibitor of soluble guanylyl cyclase (sGC), 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, 100 microM); while their sibling oocytes were subjected to ICSI either before (young) or after culture for the corresponding period of time (old). Outcomes of normal fertilization, cleavage, and development to the morula and blastocyst stages were compared. Embryos from each subgroup were also subjected to TUNEL assay for apoptosis. A significant deterioration in the ability of the oocytes to undergo normal fertilization and development to morula and blastocyst stages occurred among oocytes aged in culture medium compared to their sibling cohorts subjected to ICSI immediately after ovulation (P<0.05). This deterioration was prevented in oocytes exposed to SNAP. In contrast, exposure to L-NAME or ODQ resulted in a significant compromise in fertilization and development to the morula and blastocyst stages (P<0.05). Finally, apoptosis was noted in embryos derived from aged oocytes and those exposed to L-NAME or ODQ, but not in embryos derived from young oocytes or oocytes exposed to SNAP. Thus, NO is essential for sustenance of oocyte quality postovulation.

Effect of diet with thiram on liver antioxidant capacity and tibial dyschondroplasia in broilers

1. An experiment was conducted to study the effect of thiram on liver antioxidant capacity and incidence of tibial dyschondroplasia in broilers. 2. One hundred and twenty Avian commercial broilers were allotted at random to three treatments: control group, low thiram group (50 mg/kg) and high thiram group (100 mg/kg). 3. Blood samples were collected to determine the activity of AST (aspartate aminotransferase). At the end of the trial, broilers were killed and liver samples were collected to determine the activity of SOD (superoxide dismutase), GSH-Px (glutathione peroxidase) and MDA (malondialdehyde) content, while the right proximal tibiotarsi were dissected in longitudinal section for assessment of tibial dyschondroplasia (TD) incidence and TD score. 4. The results showed that thiram increased the incidence of TD and TD scores, increased serum AST activity and MDA content of liver, and decreased the activity of SOD and GSH-Px in the liver. 5. They suggest that thiram causes TD in broilers by reducing liver antioxidation capability and damaging liver function; this may be one of the mechanisms by which thiram causes TD in broilers.

Dithiocarbamate fungicide thiram detection: comparison of bioluminescent and fluorescent whole-cell bioassays based on hsp22 stress promoter induction

Detection of toxic substances interfering with endocrine system is one of the major preoccupations of the European community. A whole-cell bioassay for pollution detection based on stress induction has been designed. Well characterized toxicants, cadmium chloride and thiram (a dithiocarbamate fungicide), were used to optimize the detection conditions such as time-course conditions, cell line and reporter gene to be used. HeLa cells containing the firefly luciferase (luc) reporter gene under the control of the Drosophila melanogaster hsp22 promoter were compared to liver cells (HepG2) containing the same stress gene promoter fused either to the luc or the EGFP (Enhanced-Green Fluorescent Protein) gene. The sensitivity of the obtained bioassay was found to be enhanced by the concomitant use of liver cells and EGFP reporter gene. The detection limits of the toxicants were then lowered from 1 to 0.1 microM and from 1 to 0.01 microM for CdCl(2) and thiram, respectively.

Mancozeb exposure in vivo impairs mouse oocyte fertilizability

Mancozeb is known to alter reproductive performance in exposed animals, but its specific mechanism of action is still unclear. We investigated whether in female mice of the F1 generation, mancozeb could affect oocyte ability to undergo complete meiotic maturation and fertilization. Female mice were treated with 50 and 500 mg/kg of mancozeb (or vehicle in the controls) from gestational day 2 to postnatal day 20. Results demonstrated that only at the highest dose, mancozeb induced a significant decrease in the number of ovulated eggs. Moreover, at this dose mancozeb caused a significant decrease of fertilizability related to a reduction of the formation of male and female pronuclei.

Mancozeb adversely affects meiotic spindle organization and fertilization in mouse oocytes

In this study the effects of mancozeb, a widely used ethylenebisdithiocarbamate fungicide, on mouse oocyte meiotic maturation and fertilization were analyzed. Oocyte cumulus cell-complexes were matured in vitro with or without increasing concentrations of the fungicide (from 0.001 to 1 microg/ml) that, due to its different stability in organic solvents and in water, was resuspended either in dimethyl sulfoxide or in culture medium. Although, about 95% of oocytes reached the metaphase II stage; mancozeb-exposed oocytes showed a dose-dependent increase of alterations in spindle morphology, and this negative effect was more evident when the fungicide was resuspended in culture medium. Under the latter culture condition, oocytes matured in the presence of 0.1 and 1 microg/ml mancozeb showed a significant reduction also in the formation of male and female pronuclei. These results indicate that mancozeb can adversely affect mammalian reproductive performance, likely by perturbing microtubular organization during meiotic maturation.

Guidance on setting of acute reference dose (ARfD) for pesticides

This paper summarises and extends the work developed over the last decade by the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) for acute health risk assessment of agricultural pesticides. The general considerations in setting of acute reference doses (ARfDs) in a step-wise process, as well as specific considerations and guidance regarding selected toxicological endpoints are described in detail. The endpoints selected are based on the practical experience with agricultural pesticides by the JMPR and are not a comprehensive listing of all possible relevant endpoints. Haematotoxicity, immunotoxicity, neurotoxicity, liver and kidney toxicity, endocrine effects as well as developmental effects are taken into account as acute toxic alerts, relevant for the consideration of ARfDs for pesticides. The general biological background and the data available through standard toxicological testing for regulatory purposes, interpretation of the data, conclusions and recommendations for future improvements are described for each relevant endpoint. The paper also considers a single dose study protocol. This type of study is not intended to be included in routine toxicological testing for regulatory purposes, but rather to guide further testing when the current database indicates the necessity for an ARfD but does not allow a reliable derivation of the value.