Transcriptome analysis of Fenneropenaeus merguiensis in response to Vibrio proteolyticus infection.

In recent years, due to the destruction of the culture environment and serious ecological pressure, especially in the process of culture, residual bait, faeces and fishery drug abuse will lead to the accumulation of harmful metabolites such as ammonia nitrogen and nitrite, and biological denitrification is the most economical and effective method to remove the single. Therefore, in this study, a nitrite removal strain XA19 was isolated and screened from a shrimp biofloc culture pond. This strain was identified as a clade of Vibrio proteolyticus because the homology between XA19 and V. proteolyticus WDVP was as high as 99.86% by using 16S rDNA gene sequence analysis and NCBI database comparison. Scanning electron microscopy images showed that V. proteolyticus is short-rod-shaped with a curved body and no budding spores, pods and flagella. Antimicrobial susceptibility test proved that V. proteolyticus was resistant to ampicillin, oxacillin, penicillin, vancomycin and clindamycin. In the median lethal concentration 50 (LC50 ) test, at 7-day post-infection (dpi), LC50 of V. proteolyticus for Fenneropenaeus merguiensis was 1.69 × 104 CFU/mL. Transcriptome sequencing analysis was carried out on hepatopancreas of F. merguiensis at 24 and 48 hpi. A total of 176 differentially expressed genes (DEGs) were screened at 24 hpi, including 104 up-regulated DEGs and 72 down-regulated DEGs, and a total of 52 DEGs were screened at 48 hpi, including 32 up-regulated DEGs and 20 down-regulated DEGs. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs, many immune-related signalling pathways were significantly enriched, including Hippo signalling pathway, phagosome, Toll and Imd signalling pathways and Wnt signalling pathway. In addition, some pathways related to Warburg effect were also enriched, including Glycolysis/Gluconeogenesis, Biosynthesis of amino acids, amino sugar and nucleotide sugar metabolism and so on. In this study, the toxicity and drug sensitivity of V. proteolyticus were systematically studied, and the immune response of hepatopancreas of F. merguiensis to V. proteolyticus infection was preliminarily revealed from the molecular level. The results may provide a reference for the prevention and control of V. proteolyticus.

Entomopathogenicity of Ascomycete Fungus Cordyceps militaris on the Cotton Bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae).

This study investigated the exposure of the cotton bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) to a novel pathogenic fungal agent historically associated with human medicinal value, a commercial strain of Cordyceps militaris ((L.) Fr.) Vuill. (Hypocreales). A series of comparative studies were conducted to evaluate the efficacy of two different exposure methods using four concentrations (n × 109, n × 108, n × 107, n × 106) of C. militaris, where n × 109 provided a concentration of approximately 420 ± 37 spores per mm2 with 398 ± 28 viable spores. Survival of cotton bollworms of all stages was not affected by C. militaris at any concentration 1 d post-exposure. The greatest reduction in survival and highest sporulation rates were observed primarily on or after 7 d post-exposure for early instars (first and second). Significant declines in the survival of early instars were observed for all concentrations at 7 d, and 95% mortality by 10 d, with the exception of the fifth instars that experienced a less severe reduction in survival (35%) when exposed to any concentrations used in the study. Survival of late instars (third to fifth) ranged from 44% to 68% on day 10, while adult survival was near 99% across the duration of the experiment. The relatively narrow range observed for both the lethal concentration and sporulation of second, third, and fifth instar cotton bollworms exposed to the C. militaris strain may demonstrate potential field application for control of larval populations of cotton bollworms.

Assessment of acute inhalation toxicity of citric acid and sodium hypochlorite in rats.

BACKGROUND: Citric acid (CA) and sodium hypochlorite (NaOCl) have been used to disinfect animals to protect them against avian influenza and foot-and-mouth disease. OBJECTIVES: We performed a good laboratory practice (GLP)-compliant animal toxicity study to assess the acute toxic effects of CA and NaOCl aerosol exposure in Sprague-Dawley rats. METHODS: Groups of five rats per sex were exposed for 4 h to four concentrations of the two chemicals, i.e., 0.00, 0.22, 0.67, and 2.00 mg/L, using a nose-only exposure. After a single exposure to the chemicals, clinical signs, body weight, and mortality was observed during the observation period. On day 15, an autopsy, and then gross findings, and histopathological analysis were performed. RESULTS: After exposure to CA and NaOCl, body weight loss was observed but recovered. Two males died in the CA 2.00 mg/L group and, two males and one female died in the 2.00 mg/L NaOCl group. In the gross findings and histopathological analysis, discoloration of the lungs was observed in the CA exposed group and inflammatory lesions with discoloration of the lungs were observed in the NaOCl exposed group. These results suggest that the lethal concentration 50 (LC50) of CA is 1.73390 mg/L for males and > 1.70 mg/L for females. For NaOCl, the LC50 was 2.22222 mg/L for males and 2.39456 mg/L for females. CONCLUSIONS: The Globally Harmonized System is category 4 for both CA and NaOCl. In this study, the LC50 results were obtained through a GLP-based acute inhalation toxicity assessment. These results provide useful data to reset safety standards for CA and NaOCl use.

Bayesian modelling of response to therapy and drug-sensitivity in acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is a heterogeneous haematologic malignancy involving the abnormal proliferation of immature lymphocytes and accounts for most paediatric cancer cases. The management of ALL in children has seen great improvement in the last decades thanks to greater understanding of the disease leading to improved treatment strategies evidenced through clinical trials. Common therapy regimens involve a first course of chemotherapy (induction phase), followed by treatment with a combination of anti-leukemia drugs. A measure of the efficacy early in the course of therapy is the presence of minimal residual disease (MRD). MRD quantifies residual tumor cells and indicates the effiectiveness of the treatment over the course of therapy. MRD positivity is defined for values of MRD greater than 0.01%, yielding left-censored MRD observations. We propose a Bayesian model to study the relationship between patient features (leukemia subtype, baseline characteristics, and drug sensitivity profile) and MRD observed at two time points during the induction phase. Specifically, we model the observed MRD values via an auto-regressive model, accounting for left-censoring of the data and for the fact that some patients are already in remission after the first stage of induction therapy. Patient characteristics are included in the model via linear regression terms. In particular, patient-specific drug sensitivity based on ex vivo assays of patient samples is exploited to identify groups of subjects with similar profiles. We include this information as a covariate in the model for MRD. We adopt horseshoe priors for the regression coefficients to perform variable selection to identify important covariates. We fit the proposed approach to data from three prospective paediatric ALL clinical trials carried out at the St. Jude Children's Research Hospital. Our results highlight that drug sensitivity profiles and leukemic subtypes play an important role in the response to induction therapy as measured by serial MRD measures.

Lethal Concentration and Sporulation by Contact and Direct Spray of the Entomopathogenic Fungus Beauveria bassiana on Different Stages of Nezara viridula (Heteroptera: Pentatomidae).

The southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae) is the most significant pest of soybean worldwide. The present study was conducted to compare the effectiveness of a Delta native strain NI8 of Beauveria bassiana by contact and direct spray on nymphs (2nd to 5th instar) and adults of N. viridula. Water control and four concentrations of B. bassiana were used to evaluate the survival, mortality, and molting percentage and to estimate median lethal concentration (LC50), median lethal sporulation (LS50), and resistance ratio (RR50). Direct spray at all concentrations observed the greatest reduction in survival on all life stages. Mortality and sporulation were positively correlated by concentration, while molting was highly variable with a significantly lower negative correlation on insects that were directly sprayed. Pathogenicity exhibited reduction as young stages developed and emerged to adult. The LC50 (Contact: 612 spores/mm2; Direct spray: 179 spores/mm2) and LS50 (Contact: 1960 spores/mm2 Spray: 3.3 × 106) values showed that adults of N. viridula were highly resistant than any other life stage when exposed to either contact or direct spray. Fourth instar was the most susceptible (LC50: Contact: 18 spores/mm2; Direct spray: 23 spores/mm2) (LS50: Contact: 53 spores/mm2; Direct spray: 26 spores/mm2) followed by second, third, and fifth instars.

Susceptibility of Different Life Stages of Kudzu Bug Megacopta cribraria (F.) (Hemiptera: Plataspidae) to Two Different Native Strains of Beauveria bassiana.

This is the first study that examined and compared the survival, LC50, and RR50 estimates of Megacopta cribraria F. (Hemiptera: Plataspidae) nymphs and adults that were exposed to two native Beauveria bassiana isolates (Previously codified as NI8 and KUDSC strains) at four concentrations. The greatest reduction in survival and mortality was observed primarily on or after 10 d post-exposure to B. bassiana isolates. Survival of early instars (2nd, 3rd) were not affected by either strains or concentration at 3 d and 5 d post-exposure. Survival of later instars (5th) and adults was significantly reduced when exposed to the KUDSC strain at all concentrations. Comparison of dose−mortality values (LC50) using resistance ratios (RR50) were significantly different between life stages of the kudzu bug for both strains of B. bassiana. The LC50 values showed that kudzu bug adults are more susceptible than any other life stage when exposed to either strain. The KUDSC strain was more pathogenic than NI8 10 d after exposure, but NI8 exhibited significantly higher pathogenicity than KUDSC 20 d after exposure. Our results suggest potential field application of B. bassiana for kudzu bug control and their integration into pest management strategies to suppress them before they cause economic damage to soybean crops.

Virulence of native isolates of entomopathogenic fungi (Hypocreales) against the "sweetpotato whitefly" Bemisia tabaci (Hemiptera: Aleyrodidae), including the effects of temperature and fungicides.

Hypocrella, Moelleriella and related species in the Hypocreales (Ascomycota, Sordariomycetes) cause epizootics of whiteflies and scale insects in nature. However, studies on their host specificity, virulence, infection cycles, optimal development under laboratory conditions, and compatibility with other control methods, are unexplored for most species. Under laboratory conditions, the virulence of several isolates of field-collected hypocrealean fungi (Hypocrella, Moelleriella, Regiocrella, and Verticillium) was determined on Bemisia tabaci eggs and 4th instar nymphs. In addition to virulence, the effect of temperature and two commercial fungicides on growth rates and germination of the isolates was evaluated. None of the isolates infected the eggs, while M. libera, M. ochracea, and M. turbinata caused high nymphal mortality. Moelleriella libera was the most virulent isolate. At all temperatures, M. libera, Regiocrella sp. (P17H20), and Verticillium cf. pseudohemipterigenum had the highest germination and growth rates. The optimal growth temperature depended on the isolate, but at 23 °C and 25 °C, the probability of spore germination was higher for most isolates. Finally, the fungicides azoxystrobin and chlorothalonil inhibited growth rates and conidial germination at 24 and 48 h of exposure. This research produces vital knowledge on the virulence and infection cycles of poorly studied native species of entomopathogenic fungi. In addition, the results provide information on the optimal temperature for development in laboratory conditions and susceptibility to fungicides, which could contribute to future biological control strategies.

Evaluation of the antiparasitic activity of the chitosan-silver nanocomposites in the treatment of experimentally infested pigeons with Pseudolynchia canariensis.

This study aimed to evaluate the efficacy of chitosan-silver nanocomposites in the treatment of experimentally infested pigeons with Pseudolynchia canariensis (P. canariensis) with evaluation of different immunological parameters before and after treatment. Therefore, fourteen birds were divided into 2 groups; group1(infested group including 12 birds) which subdivided into 6 sub-groups experimentally infested pigeons 2 pigeons each, and five group of them were treated with chitosan-silver nanocomposites and sub-group number 6 was treated with deltamethrin while, group 2 including two pigeons were kept as control negative ones. P. canariensis flies distributed under the wing and /or under the tail in infested group and these pigeons showed significantly lower RBCs and higher WBCs than that in non-infested pigeons. The cell mediated immune response against experimentally infested pigeons with P. canariensis was studied. P. canariensis infestation in pigeons have a negative impact on pigeon's blood parameters, increase TNF-α and IL-1ß cytokines levels. This study cleared out the role of P. canariensis in the induction of a case of oxidative stress indicated by high level of nitric oxide and malondialdehyde (MDA) with low antioxidant capacity in shape of reduced zinc concentration in the sera of experimentally infested pigeon. Chitosan-silver nanocomposite has a promising effect in the elimination of P. canariensis infestation in pigeons.

Gradual reduction of susceptibility and enhanced detoxifying enzyme activities of laboratory-reared Aedes aegypti under exposure of temephos for 28 generations.

Temephos, an organophosphate insecticide, is widely accepted for the control of Aedes aegypti, vector of infectious diseases such as dengue, chikungunya, yellow fever, and zika. However, there are claims that repeated and indiscriminate use of temephos has resulted in resistance development in exposed mosquito populations. The present study attempts to evaluate the continuous performance of temephos on the Ae. aegypti population, in laboratory conditions, in terms of toxicity and the effect on marker enzymes associated with metabolic resistance. Results of the toxicity bioassay showed that after the initial exposure, toxicity increased till F4 generation by 1.65 fold, and continuous exposure resulted in a 7.83 fold reduction in toxicity at F28 generation. Percent mortality result showed a marked reduction in mortality with the passage of generations while using the same series of concentrations, viz. 2 ppm, which was 100 % lethal at the initial nine generations, could kill only 22.66 % at F28. Resistance to organophosphates is mainly governed by metabolic detoxifying enzyme families of esterases, glutathione-s-transferase, and cytochrome P450. Analysis of these metabolic detoxifying enzymes showed an inverse trend to toxicity (i.e. toxicity increased in early generations as enzyme activity dropped and then dropped as enzyme activity increased). At the initial exposure, enzyme activity decreased in 2-4 generations, however, repeated exposure led to a significant increase in all the metabolic detoxifying enzymes. From the toxicity level as well as marker enzyme bioassay results, it can be inferred that mosquitoes showed increased detoxification in generational time with an increase in enzymes associated with metabolic detoxification. In conclusion, repeated application of temephos led to resistance development in Ae. aegypti which may be associated with the increase in metabolic detoxifying enzyme activities.

Determination of chemical structure and anti-Trypanosoma cruzi activity of extracts from the roots of Lonchocarpus cultratus (Vell.) A.M.G. Azevedo & H.C. Lima.

Trypanosoma cruzi is the agent of Chagas disease, an infection that affects around 8 million people worldwide. The search for new anti-T. cruzi drugs are relevant, mainly because the treatment of this disease is limited to two drugs. The objective of this study was to investigate the trypanocidal and cytotoxic activity and elucidate the chemical profile of extracts from the roots of the Lonchocarpus cultratus. Roots from L. cultratus were submitted to successive extractions with hexane, dichloromethane, and methanol, resulting in LCH, LCD, and LCM extracts, respectively. Characterization of extracts was done using 1H-RMN, 13C-RMN, CC and TLC. Treatment of T. cruzi forms (epimastigotes, trypomastigotes, and amastigotes) with crescent concentrations of LCH, LCD, and LCM was done for 72, 48, and 48 h, respectively. After this, the percentage of inhibition and IC50/LC50 were calculated. Benznidazole was used as a positive control. Murine macrophages were treated with different concentrations of both extracts for 48 h, and after, the cellular viability was determined by the MTT method and CC50 was calculated. The chalcones derricin and lonchocarpine were identified in the hexane extract, and for the first time in the genus Lonchocarpus, the presence of a dihydrolonchocarpine derivative was observed. Other chalcones such as isocordoin and erioschalcone B were detected in the dichloromethane extract. The dichloromethane extract showed higher activity against all tested forms of T. cruzi than the other two extracts, with IC50 values of 10.98, 2.42, and 0.83 µg/mL, respectively; these values are very close to those of benznidazole. Although the dichloromethane extract presented a cytotoxic effect against mammalian cells, it showed selectivity against amastigotes. The methanolic extract showed the lowest anti-T. cruzi activity but was non-toxic to peritoneal murine macrophages. Thus, the genus Lonchocarpus had demonstrated in the past action against epimastigotes forms of T. cruzi but is the first time that the activity against infective forms is showed, which leading to further studies with in vivo tests.

Unveiling pharmacological studies provide new insights on Mangifera longipes and Quercus gomeziana.

Mangifera longipes and Quercus gomeziana both is an ethnomedicinally important Asian herb that has been known for numerous healing activity of tribal people. The present research aims to investigate the phytochemical analysis with in vitro, in vivo possibilities of the soluble ethanol extract of M. longipes root (EEMLR) and Q. gomeziana leaves (EEQGL) by an experimental approach. The plant extract of EEMLR and EEQGL was found secondary metabolites, notably steroids, glycosides, tannins, flavonoids, saponins, gums, and alkaloids. Additionally, the extract showed significant activity in antioxidant, antipyretic, anti-inflammatory, membrane stabilization, cytotoxic, thrombolytic, and analgesic activities while no response in antibacterial activity. Our findings reveal that soluble ethanol extract of EEMLR and EEQGL is safe, which can be an effective source for exploring new medicinal products. This research's outcomes may provide potentials for mitigating pyrexia, inflammation, pain, cellular toxicity, and coagulation.

A Laboratory Diet-Overlay Bioassay to Monitor Resistance in Lygus lineolaris (Hemiptera: Miridae) to Insecticides Commonly Used in the Mississippi Delta.

A laboratory, diet-overlay pesticide bioassay was developed using a susceptible population of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), to study its susceptibility to neonicotinoid, sulfoxamine, organophosphate, and pyrethroid insecticides (thiamethoxam, sulfoxaflor, acephate, and permethrin, respectively). The diet-overlay bioassay was compared to the traditional glass-vial surface residue bioassay. We measured LC50 values by feeding tarnished plant bug adults known doses of insecticides dispensed on top of diet in a 10% solution of honey water for thiamethoxam and 10% acetone in water solutions for permethrin, acephate, and sulfoxaflor. Both the diet-overlay and glass-vial bioassays used dose-response (mortality) regression lines to calculate LC50 values for each insecticide at 6-, 24-, 48-, and 72-h post-exposure. Data variability from the glass-vial bioassay was higher for permethrin, sulfoxaflor, and thiamethoxam than the diet-overlay bioassay, for all evaluation times. In contrast, there was lower variability among replicates to acephate in the glass-vial assay compared to the diet-overlay assay. Control mortalities observed on diet-overlay bioassay were lower (0-5%) than those observed on the glass-vial bioassay (4-27%). The use of green beans, floral-foam, rolling glass vials, and insect handling made the existing standard method tedious to manipulate and difficult to handle large numbers of individuals. The nonautoclaved solid diet provides an opportunity to significantly reduce cost and variability associated with procedures of other bioassay methods. In general, the baseline data provide a basis for future comparison to determine changes in resistance over time.

Pharmacological and computer-aided studies provide new insights into Millettia peguensis Ali (Fabaceae).

Millettia peguensis, popular for its ethnopharmacological uses, was employed to evaluate its different pharmacological properties in this study. The analgesic studies of the plant have been performed by acetic acid-induced writhing and formalin-induced licking tests respectively, whereas the antidiarrheal experiment was done by castor oil-induced diarrheal test. Besides, antioxidant, cytotoxic, antimicrobial, thrombolytic evaluations were performed by DPPH scavenging with phenol content determination, brine shrimp lethality, disc diffusion and clot lysis methods respectively. Moreover, in silico study of the phytoconstituents was carried out by molecular docking and ADME/T analysis. The methanol extract of Millettia peguensis (MEMP) revealed significant biological activity in the analgesic and antidiarrheal test (p < 0.001) compared to the standards. Antioxidant assay displayed promising IC50 values (15.96 µg/mL) with the total phenol content (65.27 ± 1.24 mg GAE/g). In the cytotoxicity study, the LC50 value was found to be 1.094 µg/mL. Besides, MEMP was highly sensitive to the bacteria but less liable to clot lysis. Furthermore, phytoconstituents exposed potential binding affinity towards the selected receptors, whereas the ADME/T properties indicated the drug likeliness of the plant. The outcomes of these findings suggest the therapeutic potential of this plant against pain, diarrhea, inflammation, and tissue toxicity.

Investigation of PPCPs in wastewater treatment plants in Greece: occurrence, removal and environmental risk assessment.

In the present work, an extensive study on the presence of eighteen pharmaceuticals and personal care products (PPCPs) in eight wastewater treatment plants (WWTPs) of Greece has been conducted. The study covered four sampling periods over 1-year, where samples (influents; effluents) from eight WWTPs of various cities in Greece were taken. All WWTPs investigated are equipped with conventional activated sludge treatment. A common pre-concentration step based on SPE was applied, followed by LC-UV/Vis-ESI-MS. Further confirmation of positive findings was accomplished by using LC coupled to a high resolution Orbitrap mass spectrometer. The results showed the occurrence of all target compounds in the wastewater samples with concentrations up to 96.65 µg/L. Paracetamol, caffeine, trimethoprim, sulfamethoxazole, carbamazepine, diclofenac and salicylic acid were the dominant compounds, while tolfenamic acid, fenofibrate and simvastatin were the less frequently detected compounds with concentrations in effluents below the LOQ. The removal efficiencies showed that many WWTPs were unable to effectively remove most of the PPCPs investigated. Finally, the study provides an assessment of the environmental risk posed by their presence in wastewaters by means of the risk quotient (RQ). RQs were more than unity for various compounds in the effluents expressing possible threat for the aquatic environment. Triclosan was found to be the most critical compound in terms of contribution and environmental risk, concluding that it should be seriously considered as a candidate for regulatory monitoring and prioritization on a European scale on the basis of realistic PNECs. The results of the extensive monitoring study contributed to a better insight on PPCPs in Greece and their presence in influent and effluent wastewaters. Furthermore, the unequivocal identification of two transformation products of trimethoprim in real wastewaters by using the advantages of the LTQ Orbitrap capabilities provides information that should be taken into consideration in future PPCP monitoring studies in wastewaters.

The identification and characterisation of a new deltamethrin resistance-associated gene, UBL40, in the diamondback moth, Plutella xylostella (L.).

Differential expression of ubiquitin was previously reported between Plutella xylostella strains that are resistant or susceptible to the pesticide deltamethrin (DM). This finding hinted at the potential involvement of ubiquitin in deltamethrin resistance, a theory that demanded further testing. Real-time PCR analyses revealed that one of the ubiquitin genes, UBL40, was overexpressed in the deltamethrin-resistant strain during the fourth instar. To investigate the functional relationship between this gene and deltamethrin resistance, RNA interference (RNAi) and cell transfection were utilised. UBL40 knockdown was observed to significantly reduce the level of resistance in RNAi-treated larvae after 48 h. Conversely, overexpression of UBL40 in Drosophila Kc cells conferred a degree of protection against deltamethrin. These results represent the first evidence that UBL40 plays a role in the regulation of deltamethrin resistance in P. xylostella.

Chronic cadmium exposure in vitro induces cancer cell characteristics in human lung cells.

Cadmium is a known human lung carcinogen. Here, we attempt to develop an in vitro model of cadmium-induced human lung carcinogenesis by chronically exposing the peripheral lung epithelia cell line, HPL-1D, to a low level of cadmium. Cells were chronically exposed to 5 µM cadmium, a noncytotoxic level, and monitored for acquired cancer characteristics. By 20 weeks of continuous cadmium exposure, these chronic cadmium treated lung (CCT-LC) cells showed marked increases in secreted MMP-2 activity (3.5-fold), invasion (3.4-fold), and colony formation in soft agar (2-fold). CCT-LC cells were hyperproliferative, grew well in serum-free media, and overexpressed cyclin D1. The CCT-LC cells also showed decreased expression of the tumor suppressor genes p16 and SLC38A3 at the protein levels. Also consistent with an acquired cancer cell phenotype, CCT-LC cells showed increased expression of the oncoproteins K-RAS and N-RAS as well as the epithelial-to-mesenchymal transition marker protein Vimentin. Metallothionein (MT) expression is increased by cadmium, and is typically overexpressed in human lung cancers. The major MT isoforms, MT-1A and MT-2A were elevated in CCT-LC cells. Oxidant adaptive response genes HO-1 and HIF-1A were also activated in CCT-LC cells. Expression of the metal transport genes ZNT-1, ZNT-5, and ZIP-8 increased in CCT-LC cells culminating in reduced cadmium accumulation, suggesting adaptation to the metal. Overall, these data suggest that exposure of human lung epithelial cells to cadmium causes acquisition of cancer cell characteristics. Furthermore, transformation occurs despite the cell's ability to adapt to chronic cadmium exposure.

Toxicity of Methylcyclohexane and Its Effect on the Reproductive System in SD Rats.

OBJECTIVES: There is limited data regarding the toxicity of methylcyclohexane, despite its wide use in rubber adhesives, paint diluents, and cleansing agents. This study aimed to verify the toxicity and influence on the reproductive system of methylcyclohexane after its repeated injection in Sprague Dawley (SD) rats. METHODS: Methylcyclohexane was injected subcutaneously into male and female SD rats once a day, five times a week, for 13 weeks at different doses (0, 10, 100, and 1,000 mg/kg/day) for each group. The toxicity of testing material was verified by observing the change in body and organ weight, hematological change, pathological findings, and effect on the reproductive system at each different concentration. RESULTS: In the 1,000 mg/kg/day group, there were cases of animal deaths. In animals that survived, hematological changes, including a decrease in the red blood cell count, were observed. A considerable weight gain or loss and pathological abnormalities in the liver, kidney, and other organs were found. However, the 10 and 100 mg/kg/day groups did not cause deaths or other specific abnormalities. In terms of reproductive toxicity, there were changes in hormone levels, including a significant decrease in hormones such as estradiol and progesterone (p < 0.001) in male animals. Menstrual cycle change for female animals did not show concentration dependency. CONCLUSION: When injected repeatedly for 13 weeks, methylcyclohexane proved to be toxic for the liver, heart, and kidney at a high dose. The absolute toxic dose was 1,000 mg/kg/day, while the no observed adverse effect level was less than 100 mg/kg/day. The substance exerted little influence on the reproductive system.