Detection and Exclusion of False-Positive Molecular Formula Assignments via Mass Error Distributions in UHR Mass Spectra of Natural Organic Matter.

Ultrahigh resolution mass spectrometry (UHRMS) routinely detects and identifies thousands of mass peaks in complex mixtures, such as natural organic matter (NOM) and petroleum. The assignment of several chemically plausible molecular formulas (MFs) for a single accurate mass still poses a major problem for the reliable interpretation of NOM composition in a biogeochemical context. Applying sensible chemical rules for MF validation is often insufficient to eliminate multiple assignments (MultiAs)─especially for mass peaks with low abundance or if ample heteroatoms or isotopes are included - and requires manual inspection or expert judgment. Here, we present a new approach based on mass error distributions for the identification of true and false assignments among MultiAs. To this end, we used the mass error in millidalton (mDa), which was superior to the commonly used relative mass error in ppm. We developed an automatic workflow to group MultiAs based on their shared formula units and Kendrick mass defect values and to evaluate the mass error distribution. In this way, the number of valid assignments of chlorinated disinfection byproducts was increased by 8-fold as compared to only applying 37Cl/35Cl isotope ratio filters. Likewise, phosphorus-containing MFs can be differentiated against chlorine-containing MFs with high confidence. Further, false assignments of highly aromatic sulfur-containing MFs ("black sulfur") to sodium adducts in negative ionization mode can be excluded by applying our approach. Overall, MFs for mass peaks that are close to the detection limit or where naturally occurring isotopes are rare (e.g., 15N) or absent (e.g., P and F) can now be validated, substantially increasing the reliability of MF assignments and broadening the applicability of UHRMS analysis to even more complex samples and processes.

Staphylococcal enterotoxin B exposed to pregnant rats inhibits the hedgehog signaling pathway in thymic T lymphocytes of the offspring.

The Hedgehog (Hh) signaling pathway is involved in T cell differentiation and development and plays a major regulatory part in different stages of T cell development. A previous study by us suggested that prenatal exposure to staphylococcal enterotoxin B (SEB) changed the percentages of T cell subpopulation in the offspring thymus. However, it is unclear whether prenatal SEB exposure impacts the Hh signaling pathway in thymic T cells. In the present study, pregnant rats at gestational day 16 were intravenously injected once with 15 µg SEB, and the thymi of both neonatal and adult offspring rats were aseptically acquired to scrutinize the effects of SEB on the Hh signaling pathway. It firstly found that prenatal SEB exposure clearly caused the increased expression of Shh and Dhh ligands of the Hh signaling pathway in thymus tissue of both neonatal and adult offspring rats, but significantly decreased the expression levels of membrane receptors of Ptch1 and Smo, transcription factor Gli1, as well as target genes of CyclinD1, C-myc, and N-myc in Hh signaling pathway of thymic T cells. These data suggest that prenatal SEB exposure inhibits the Hh signaling pathway in thymic T lymphocytes of the neonatal offspring, and this effect can be maintained in adult offspring via the imprinting effect.

Temperature-Independent Sensor of the Magnetic Field Based on FBG and Terfenol-D.

Sensors based on Fiber Bragg Grating (FBG) have remarkable benefits like small size, fast response, wide sensing distribution, and immunity to electromagnetic interference, allowing for their widespread application in numerous domains of physical parameter measurement in industrial engineering. In this work, a temperature-independent sensor of the magnetic field based on FBG and the magnetostrictive material Terfenol-D is suggested. By exploiting the distributed sensing characteristic of FBG, a sensing structure that remains unaffected by temperature is designed. The results demonstrate that within the magnetic induction intensity range of 0 mT to 50 mT, the sensitivity of the sensor can reach 7.382 pm/mT, exhibiting good linearity and repeatability. Compared with the control experiment and other sensors of the magnetic field containing Terfenol-D, the sensor has higher sensitivity, better repeatability, and good temperature stability.

Prenatal Exposure of Rats to Staphylococcal Enterotoxin B Alters the Expression of Th1 and Th2 Cytokines via Decreased Methylation in the Spleen of Adult but not Neonatal Offspring.

BACKGROUND: The methylation of IFN-γ and IL-4 genes is regarded as an epigenetic regulation that maintains the Th1 or Th2 phenotype. OBJECTIVE: To explore the influence of prenatal administration of the staphylococcal enterotoxin B (SEB) in pregnant rats, on the IFN-γ or IL-4 expression in the offspring spleen. METHODS: The SEB or PBS was administered intravenously to pregnant rats on the embryo-day 16. After normal delivery, the spleens from the fifth-day neonates and adult offspring were isolated under anesthesia. Quantitative PCR, western blot, ELISA and MeDIP-qPCR were applied to determine the levels of the splenic IFN-γ or IL-4 mRNAs, their protein levels, and methylation status, respectively. RESULTS: Prenatal administration of the SEB in pregnant rats decreased the levels of the splenic IFN-γ and IL-4 proteins in neonates, but increased their mRNA levels. However, prenatal administration of the SEB significantly augmented both mRNA and protein levels of the IFN-γ and IL-4 in the adult spleen. In addition, the prenatal SEB administration decreased the methylation of the splenic IFN-γ and IL-4 in adult but not neonatal offspring. CONCLUSION: The prenatal administration of SEB in pregnant rats can cause a mixed Th1 and Th2 cytokines response in the offspring spleen, and alter the cytokine expression of the Th1 and Th2 via decreasing the methylation in adult but, not neonatal offspring spleen.

Generation of atomic hydrogen by Ni-Fe hydroxides: Mechanism and activity for hydrodechlorination of trichloroethylene.

Atomic hydrogen (H•) is highly reactive for the hydrodechlorination of trichloroethylene (TCE). In this work, we found that the coprecipitation of Ni2+ and Fe2+ at neutral pH led to an unprecedented catalytic generation of H•. The generated H• effectively dechlorinate TCE to nontoxic ethylene and ethane, and Fe2+ is the only electron donor. The abundant adsorbed H• produced with a Ni/Fe ratio of 0.4 enhances hydrogen evolution reaction causing a low efficiency for hydrodechlorination. In contrast, the active absorbed H• is generated in the crystal lattice of Ni-Fe hydroxides with a Ni/Fe ratio of 3.0 causing highly efficient hydrodechlorination of TCE. This work not only reveals the mechanism of catalytic hydrodechlorination by Ni-Fe hydroxides at neutral pH, but also provides a novel approach to detoxify TCE in contaminated water using facile precipitated Ni-Fe hydroxides.

Molecular insight into the variation of dissolved organic phosphorus in a wastewater treatment plant.

To date, eutrophication becomes a great concern of vulnerable aquatic systems. Dissolved organic phosphorus (DOP) discharged from wastewater treatment plant (WWTP) holds a large source of phosphorus in receiving water. However, due to the complexity of DOP, their variation and fate in WWTP remain unknown at the molecular level, and are always overlooked. Here, the variation of DOP in a WWTP was uncovered via Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Results show that 95% of DOP in the influent could be removed by the secondary biological treatment processes. The removed DOP species were mainly lipids with the molecular characteristics of low oxygen content, low unsaturation and low aromaticity. Meanwhile, during biological treatments, some new DOP species, especially lignin/carboxylic rich alicyclic molecules (CRAM) that possessed high oxygen content, high unsaturation and high aromaticity, were produced and released into the secondary effluent. In the subsequent tertiary treatment, coagulation by aluminum salt tended to remove high molecular weight and high oxygen content DOP species in the secondary effluent, which was complementary to the biological treatment. However, the sand filter usually retained microorganisms, which would result in the generation of new DOP species in this process. During the final ultraviolet disinfection process, DOP was effectively mineralized to phosphate, especially the species with high molecular weight and highly unsaturated aromatic DOP species (e.g., lignin/CRAM and tannin), which had higher UV absorbance. The revealed variation of DOP in WWTP is beneficial to optimize the treatment processes to enhance the removal of DOP.

Exposure of pregnant rats to staphylococcal enterotoxin B increases offspring splenic Treg number and function via decreasing FoxP3 methylation.

Staphylococcus aureus is an infectious pathogen that is relatively common, but that can cause severe disease in pregnant women and their fetus. We previously demonstrated that exposing pregnant rats to staphylococcal enterotoxin B (SEB) altered splenic CD4/CD8 T cell frequencies in their offspring. Whether prenatal SEB exposure impacts Tregs in these offspring, however, remains to be determined. As such, in this study, we intravenously injected pregnant rats with 15 µg of SEB on gestational day 16. Splenic tissue was then harvested from 1-, 3-, and 5-day-old neonatal rats and analyzed via flow cytometry to assess Treg numbers. In addition, FoxP3 expression levels were assessed via qPCR and western blotting, while FoxP3 methylation status was evaluated via methyl-DNA immunoprecipitation qPCR. Immunosuppression assays were additionally used to gauge Treg suppressive functionality. We found that exposing pregnant rats to SEB resulted in a significant increase in Treg numbers, FoxP3 expression, and Treg suppressive capacity in the spleens of both neonatal and adult offspring. In addition, total T cell, CD4+T cell, and non-Treg CD4+ T cell numbers were elevated in the spleens of offspring following prenatal SEB exposure. We additionally determined that SEB exposure resulted in a significant reduction in FoxP3 DNA methylation. Together, our results indicate that prenatal SEB exposure can markedly enhance offspring splenic Treg numbers and functionality at least in part by decreasing FoxP3 methylation.

Effects of phenol on extracellular polymeric substances and microbial communities from aerobic granular sludge treating low strength and salinity wastewater.

The effects of phenol on aerobic granular sludge including extracellular polymeric substances (EPS) and microbial community were investigated for low strength and salinity wastewater treatment. Elevated phenol over 20 mg/L stimulated biological phosphorus removal mainly via co-metabolism with nearly complete phenol degradation, whereas resulted in significant accumulation of nitrate around 4 mg/L. Aerobic granules kept structural stability via enhancing production of extracellular polymeric substances (EPS), especially folds of polysaccharides (PS) and varying functional groups identified through EEM, FTIR and XPS spectral characterizations at increasing phenol loads. Illumina MiSeq sequencing results indicated that elevated phenol decreased the bacterial diversity and richness, and caused remarkable variations in structural and compositions of microbial population. Multiple halophilic bacteria including Stappia, Luteococcus, and Formosa laid the biological basis for stability of aerobic granules and efficient biological nutrients and phenol removal. Redundancy analysis (RDA) suggested the key role of phenol in shaping the relative abundances and predominant genera. This study proved that aerobic granular sludge was feasible for low-saline and phenol-laden low-strength wastewater treatment.

Interaction and removal of oxytetracycline with aerobic granular sludge.

Aerobic granular sludge as a promising technology showed great resistance to adverse conditions. However, the interaction between oxytetracycline (OTC) and granular sludge was not studied sufficiently. This study therefore investigated OTC-tolerance ability of incomplete and complete granulation sludge from aspects of simultaneous nutrients removal, sludge characteristics, microbial activity, community changes, and vice versa OTC removal performance. Incomplete granulation sludge showed better denitrification performance and resistance. Whereas, denitrification and phosphorus removal of complete granulation sludge suffered a permanent collapse under 5 mg/L OTC. OTC could be removed by rapid adsorption and slow biodegradation via granular sludge. The EPS, especially TB-PS, played a significant role during the operational period subjected to OTC. The major genera of Lysobacter and Candidatus_Competibacter laid the biological basis for stability and functionality of granules, which acted as the putative contributors for resisting and removing OTC. This study showed that incomplete-granulated sludge qualified more promising application prospect.

Exposure of pregnant rats to staphylococcal enterotoxin B attenuates the response of increased Tregs to re-exposure to SEB in the thymus of adult offspring.

Regulatory T cells (Tregs) play an essential role during homeostasis and tolerance of the immune system. Based on our previous study that exposure of pregnant rats to staphylococcal enterotoxin B (SEB) can alter the percentage of CD4/CD8 subsets in the thymus of the offspring, in this study, we focus on the influence of exposure of pregnant rats to SEB on number, function and response of Tregs in the thymus of the offspring. Pregnant rats at gestational day of 16 were intravenously injected with 15 µg SEB and the thymuses of the neonatal and adult offspring were harvested for this study. We found that exposure of pregnant rats to SEB could significantly increase the absolute number of Tregs and the FoxP3 expression level in the thymus of not only neonatal but also adult offspring. Re-exposure of adult offspring to SEB remarkably reduced the suppressive capacity of Tregs to CD4+ T cells and the expression levels of TGF-ß and IL-10 in the thymus, but had no effect on production of IL-4 and IFN-γ. Furthermore, it also notedly decreased the absolute number of Tregs and the FoxP3 expression level. These data suggest that prenatal exposure of pregnant rats to SEB attenuates the response of increased Tregs to re-exposure to SEB in the thymus of adult offspring.

Prenatal exposure of staphylococcal enterotoxin B attenuates the development and function of blood regulatory T cells to repeated staphylococcal enterotoxin B exposure in adult offspring rats.

Introduction. Staphylococcal enterotoxin B (SEB) is an extensively studied super-antigen. A previous study by us suggested that SEB exposure during pregnancy could alter the percentage of CD4+ and CD8+ T cells in the peripheral blood of neonatal offspring rats.Aim. It is unknown whether SEB exposure during pregnancy can influence the development of regulatory T cells (Tregs) in the peripheral blood of neonatal offspring rats.Methodology. Pregnant rats at gestational day 16 were intravenously injected with 15 µg SEB. Peripheral blood was acquired from neonatal offspring rats on days 1, 3 and 5 after delivery and from adult offspring rats for determination of Treg number by cytometry, cytokines by ELISA, and FoxP3 expression by real-time PCR and western blot.Results. SEB given to pregnant rats significantly increased the absolute number of Tregs and the expression levels of FoxP3, IL-10 and TGF-ß (P<0.05, P<0.01) in the peripheral blood of not only neonatal but also adult offspring rats. Furthermore, repeated SEB exposure in adult offspring rats significantly decreased the absolute number of Tregs (P<0.01), and the expression levels of FoxP3, IL-10 and TGF-ß (P<0.05, P<0.01) in their peripheral blood.Conclusion. Prenatal SEB exposure attenuates the development and function of Tregs to repeated SEB exposure in the peripheral blood of adult offspring rats.

Elevated salinity deteriorated enhanced biological phosphorus removal in an aerobic granular sludge sequencing batch reactor performing simultaneous nitrification, denitrification and phosphorus removal.

Hypersaline wastewater may pose threats to biological wastewater treatment processes. An aerobic granular sludge-based sequencing batch reactor (SBR) performing simultaneous nitrification, denitrification and phosphorus removal (SNDPR) was evaluated with increased salinity from 1 to 2 % (w/v). Nitrogen removal performance was unaffected by salinity up to 20 g/L in terms of reliable and efficient nitrification and denitrification. Enhanced biological phosphorus removal (EBPR) process was completely deteriorated at salinity up to 2 %, in contrast to excellent phosphorus removal at 1 %. Profiles of phosphorus over one cycle demonstrated that higher salinity not only inhibited anaerobic phosphorus release but also impeded aerobic/anoxic phosphorus uptake. Illumina MiSeq sequencing revealed multiple halophilic and non-halophilic bacteria within aerobic granules with family Anaerolineaceae being the predominant potential salt adapter. Besides, ammonia oxidizing bacteria (AOB), glycogen accumulating organisms (GAOs) were more tolerant to salt than nitrite oxidizing bacteria (NOB) and phosphorus accumulating organisms (PAOs) and denitrifying PAOs (DNPAOs). These results deciphered the resilience of aerobic granular sludge-based biological nitrogen and phosphorus removal processes to hypersaline stress.

Enhanced simultaneous nitrification, denitrification and phosphorus removal through mixed carbon source by aerobic granular sludge.

Aerobic granular sludge-based simultaneous nitrification, denitrification and phosphorus removal (SNDPR) systems were configured for the treatment of low-strength municipal wastewater. Granular characteristics, process performance, and the corresponding microbial ecology dynamics were comprehensively explored with sodium acetate and succinate as mixed carbon source. Results revealed that aerobic granules kept structural and functional resilience, while mixed carbon source largely altered and balanced the growth and competition of phosphorus/glycogen accumulating organisms (PAOs/GAOs). Appropriate ratio of mixed carbon source was vital for superb physiochemical behaviors and reliable removal performance by aerobic granules. Therefore, the aerobic granular SNDPR system could achieve deep-level nutrients removal through enhancing the anaerobic carbon uptake rate and strengthening the carbon usage efficiency. The present work could add some guiding sight into the application of aerobic granular SNDPR system for wastewater treatment.

Robustness of an aerobic granular sludge sequencing batch reactor for low strength and salinity wastewater treatment at ambient to winter temperatures.

Acclimation performances and characteristics of aerobic granular sludge to salt and temperature were investigated in a sequencing batch reactor (SBR) performing simultaneous nitrification, denitrification and phosphorus removal (SNDPR). The aerobic granular SNDPR system was firstly subjected to low salinity (0.5%, w/v) at moderate temperature (> 15 ℃) and subsequent low temperature (< 15 ℃). The shock loading of salinity temporarily deteriorated biological phosphorus removal, while dual stresses of salinity and low temperature induced temporary inhibition on both nitrogen and phosphorus removal. Both salinity and low temperature stimulated the settleability of aerobic granules, accompanied with decreased ratios of protein to polysaccharide (PN/PS). Illumina MiSeq sequencing revealed that salinity rarely affected bacterial richness, but significantly decreased the diversity. Whereas low temperature strengthened both bacterial richness and diversity. Phyla Proteobacteria, Chloroflexi and their sub-groups acted as the main halophilic bacteria while Proteobacteria was also psychrophilic. The functional bacteria such as nitrifiers, denitrifiers, and phosphorus removal bacteria exhibited greater tolerance to salt and low temperature than glycogen accumulating organisms (GAOs). Overall, the present study demonstrated the resilience and robustness of aerobic granular sludge toward salinity and low temperature, which could aid the knowledge of saline wastewater treatment by aerobic granular sludge.

Research on the aerobic granular sludge under alkalinity in sequencing batch reactors: Removal efficiency, metagenomic and key microbes.

Effects of additional alkalinity on the performance of aerobic granular sludge (AGS) in sequencing batch reactors (SBR) performing simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) were evaluated. Results showed that COD and ammonia-N (NH4+-N) were slightly stimulated and remained high and stable with the increase of alkalinity up to 750 mg/L, while denitrification was boosted and total inorganic nitrogen (TIN) removal efficiency increased from 60.46% to 98.62% with an additional alkalinity of 750 mg/L. However, total phosphorus (TP) removal stayed unaffected and efficient. Illumina MiSeq sequencing revealed that microbial diversity and richness shifted mostly with 500 mg/L exterior alkalinity addition. Additional alkalinity altered the bacterial compositions within aerobic granules at various levels and the enrichment of Thiothrix and Acinetobacter was accounted for the promotion of COD and TIN removal.

A comprehensive comparison between non-bulking and bulking aerobic granular sludge in microbial communities.

Filamentous sludge bulking poses great threats to operational stability of aerobic granular sludge. Exploration of the microbial community aids knowledge of the causative factors to sludge bulking and guides directions for corresponding actions for prevention and controlling. Detailed changes of bacterial community within the non-bulking and bulking were performed and compared with a non-specific method through 1‰ (v/v) hydrogen peroxide (H2O2) addition. Results revealed that non-bulking/bulking granules maintained effective carbon and nitrogen removal, while bulking completely deteriorated enhanced biological phosphorus removal (EBPR). Excess extracellular polymeric substances (EPS) especially polysaccharide (PS) were directly linked with sludge bulking and abundant PS contributed to subsequent granular re-stability. Filamentous bulking dramatically altered the bacterial populations and 1‰ H2O2 effectively controlled bulking by eliminating causative filaments Singulisphaera and Thiothrix. Together, this study provides new insights into the non-bulking/bulking granules and could direct the prevention and control of filamentous bulking in aerobic granules.

Mitigated membrane fouling and enhanced removal of extracellular antibiotic resistance genes from wastewater effluent via an integrated pre-coagulation and microfiltration process.

Antibiotic resistance genes (ARGs) have been regarded as an emerging pollutant in municipal wastewater treatment plant (WWTP) effluents due to their potential risk to human health and ecological safety when reused for landscape and irrigation. Conventional wastewater treatment processes generally fail to effectively reduce ARGs, especially extracellular ARGs (eARGs), which are persistent in the environment and play an important role in horizontal gene transfer via transformation. Herein, an integrated process of pre-coagulation and microfiltration was developed for removal of ARGs, especially eARGs, from wastewater effluent. Results show that the integrated process could effectively reduce the absolute abundances of total ARGs (tARGs) (>2.9 logs) and eARGs (>5.2 logs) from the effluent. The excellent performance could be mainly attributed to the capture of antibiotic resistant bacteria (ARB) and eARGs by pre-coagulation and co-rejection during subsequent microfiltration. Moreover, the integrated process exhibited a good performance on removing common pollutants (e.g., dissolved organic carbon and phosphate) from the effluent to improve water quality. Besides, the integrated process also greatly reduced membrane fouling compared with microfiltration. These findings suggest that the integrated process of pre-coagulation and microfiltration is a promising advanced wastewater treatment technology for ARGs (especially eARGs) removal from WWTP effluents to ensure water reuse security.

[Effect of cordycepin on apoptosis and autophagy of tongue cancer cells in vitro and the molecular mechanism].

OBJECTIVE: To study the effect of cordycepin on cell cycle, apoptosis and autophagy of human tongue cancer TCA-8113 cells and explore the mechanism of cordycepin for inhibiting the occurrence of tongue cancer. METHODS: CCK-8 method was used to assess the inhibitory effect of cordycepin on TCA-8113 cell proliferation in vitro. The cell cycle and cell apoptosis of TCA-8113 cells treated with different concentrations of cordycepin were analyzed using flow cytometry. The expressions of apoptosis-related genes caspase-3, caspase-9, Bcl-2, and Bax were examined using quantitative real-time PCR and Western blotting, and immunohistochemistry was used to detect the expressions of autophagy-related proteins LC-3ß, P62, p-mTOR, and AMPK. RESULTS: CCK-8 assay showed that cordycepin significantly inhibited the proliferation of TCA-8113 cells in a concentration-dependent manner with an IC50 of 3.548 mg/mL at 24 h and an IC50 of 1.185 mg/mL at 48 h. Flow cytometric analysis showed that cordycepin caused cell cycle arrest at S phase and dose-dependently increased the apoptotic rate of TCA-8113 cells. Treatment of the cells with cordycepin enhanced the expressions of Bax, caspase-3 and caspase-9 at both the mRNA and protein levels and inhibited the expression of the antiapoptotic gene Bcl-2. Immunohistochemistry demonstrated that cordycepin promoted the expression of LC-3ß and AMPK and inhibited the expression of P62 and p-mTOR. CONCLUSION: Cordycepin inhibits the proliferation and induces apoptosis of HCT-116 cells through the mitochondrial pathway and induces autophagy via the AMPK/mTOR pathway.

Chronic responses of aerobic granules to zinc oxide nanoparticles in a sequencing batch reactor performing simultaneous nitrification, denitrification and phosphorus removal.

The reactor performance, granules characteristics and microbial population dynamics were investigated to assess the chronic responses of aerobic granules to zinc oxide nanoparticles (ZnO NPs) of 0, 5, 10 and 20mg/L for a period of 180days. The results showed that ZnO NPs stimulated COD removal, whereas caused inhibition to both nitrification and denitrification. However, biological phosphorus removal remained effective and stable. Introduction of ZnO NPs sharply decreased the respiration of granules, while did not change the settleability. Both content of extracellular polymeric substances (EPS) and the ratio of protein to polysaccharides (PN/PS) rose significantly. MiSeq pyrosequencing was employed to explore the microbial population dynamics. Results demonstrated that up to 20mg/L reduced the alpha-diversity of bacterial communities. Finally, phylogenetic classification of the dominant functional species involved in biological nutrients removal were identified to assess the effects of ZnO NPs to aerobic granules from the molecular level.

Staphylococcal enterotoxin B administration in pregnant rats alters the splenic lymphocyte response in adult offspring rats.

BACKGROUND: Our previous study suggested that SEB exposure in pregnant rats could lead to the change of T cells subpopulation in both peripheral blood and thymus of the offspring rats. However, rarely is known about the influence of SEB exposure in pregnant rats on T cell subpopulation in the spleens of offspring rats. RESULTS: SEB was intravenously administered to the pregnant rats at gestational day 16 in this study. The percentages, in vivo and in vitro responses of CD4 and CD8 T cells were investigated with flow cytometry. The prenatal SEB exposure obviously increased splenic CD4 T cell percentages of both neonates and adult offspring rats, and obviously reduced splenic CD8 T cell percentages of both the fifth day neonates and adult offspring rats. After spleens in the adult offspring rats were re-stimulated with SEB in vivo or in vitro, in vivo SEB stimulation could lead to the marked decrease of splenic CD4 T cell percentage and the marked increase of splenic CD8 T cell percentage. While in vitro SEB stimulation to the cultured splenocytes markedly decreased the proliferation of the splenic lymphocytes and the CD4 T cell percentage, and had no influence on CD8 T cell percentage. CONCLUSION: The prenatal SEB exposure could alter the percentages of CD4/CD8 T cell subpopulation and the response of CD4 and CD8 T cells to the in vivo and in vitro secondary SEB stimulation in the splenocytes of adult offspring rats.