Phosphorus removal of rural wastewater by the paddy-rice-wetland system in Tai Lake Basin

A field experiment was conducted to remove the potential eutrophication effect of P from rural wastewater (RW) during the whole rice growing season of 2007. The experiments consisted of five treatments, namely black water (BW), domestic wastewater (DW), grey water (GW), surface lake water (SW) and surface lake water without P application as a check (CK), with three replicates in a randomized block design. Commercial fertilizer and RW were applied to furnish 40 kg Pha(-1) except CK. Results showed total P (TP) concentration had significantly declined after P application, from October 15 there were no significant increases in TP concentration in the floodwater. TP removal rates from RW was significantly higher (P<or=0.05) than those from fertilizer. TP load was in an overall gradual decline, whereupon it became approximately steady on October 1. The percentage of TP load from wastewater decreased, whereas that from fertilizer continued to increase. Meanwhile, the yield for CK was significantly less (P<or=0.05) than SW, GW, DW, and BW, with the yield of BW significantly greater (P<or=0.05) than other treatments. It is feasible to remove P from RW by the paddy-rice-wetland system and can be widely used to improve the yield of rice.

Effects of pharmacological concentrations of estrogens on growth of 3AO human ovarian cancer cells

During the past two decades, the knowledge of the molecular mechanism by which estrogens exert various functions in different tissues and organs has evolved rapidly. Recent reports demonstrated that estrogen could decrease the cell growth in several types of cancer cells, including ovarian cancer cells. Though experiments explored the possible mechanism of the inhibitory effect, the exact mechanism is responsible for the effect, which remains unclear. The ovary is the main source of the estrogen, estrogen receptor is expressed in several ovarian cell types, including ovarian surface epithelium, the tissue of origin of approximately 90% of the ovarian cancers. It was of great interest to analyze the effects of 17beta-estradiol (E2) on apoptosis of ovarian cancer cells, and the identification of E2-regulated specific genes involved in epithelial proliferation apoptosis, thus may be a clue for understanding the progression of ovarian cancer and for the design of new target therapies. To elucidate the mechanism involved, effects of pharmacological concentrations of estrogen were studied in human ovarian cancer cell line 3AO cells. Inhibition of cellular growth of 3AO cells was seen with E2 at concentrations higher than 0.1 micromol/L. The estrogen receptor inhibitor ICI 182780 cannot block the inhibitory effect of E2. It was surprising to find that ICI 182780 itself can inhibit the growth of 3AO cells, and had a collaborative effect with E2. The decreased cell growth induced by E2 was shown to be apoptosis as analyzed by flow cytometry. ERbeta was detected in the 3AO ovarian cancer cell line but not ERalpha. The expression of ERbeta was weak, which may partially explain why high but not low dose of E2 needed to induce the apoptosis of 3AO cells. We also observed that membrane impermeable E2, E2-BSA have lost growth inhibitory on 3AO cells, which excluded the membrane effect of E2 as previously reported by many investigators. The p38 kinase inhibitor, SB203580 were partially protected 3AO cells against growth inhibition by E2, while inhibitor of JNK, SP600125 enhanced cell death induced by E2. These results showed that MAPK is implicated in cellular processes involving apoptosis.

Primary ovarian choriocarcinoma mimicking ectopic pregnancy managed with laparoscopy -- case report

Nongestational ovarian choriocarcinomas are extremely rare and pose diagnostic challenges in reproductive-aged patients because of elevated human chorionic gonadotrophin (hCG). A 23-year-old nulliparous Chinese woman with nongestational ovarian choriocarcinoma escaped diagnostic testing and was initially treated for an ectopic pregnancy. Three months after her first visit, a diagnostic laparoscopy demonstrated a nongestational ovarian choriocarcinoma. Comprehensive surgical staging was performed by laparoscopy. The tumor was confined to the left ovary. The patient was categorized as FIGO Stage IA. She was given four courses of combined chemotherapy after laparoscopic surgery and has been disease-free for 36 months.

Vaginal paraganglioma presenting as a gynecologic mass: case report

Paragangliomas in the vagina are extremely rare. Unwitting surgical excision of a functional paraganglioma may precipitate life-threatening complications. We present a case of a 38-year-old woman with a vaginal mass 3.0 cm in diameter who experienced a hypertensive crisis during an unwitting attempted surgical excision of the vaginal mass. The diagnosis of a vaginal functional paraganglioma was then made based on to her 16-year history of paroxysmal headaches, chest distress, palpitation and elevated levels of urinary vannillylmandelic acid (VMA). Consequently, after thorough presurgical preparation, the patient again underwent excision of the vaginal mass uneventfully. She has been followed-up for three years since surgery without any evidence of recurrence. The clinical features and perioperative management of functional vaginal paraganglioma are described.

Modeling transport and fate of nitrogen from urea applied to a near-trench paddy field

A simple but comprehensive model is developed to quantify N losses from urea applied to a near-trench paddy field, considering all the N-transformations such as urea hydrolysis, volatilization, nitrification, denitrification, and all the important transportations like runoff, lateral seepage, vertical leaching and crop uptake. Seasonal average data of field observations for three crop seasons were used for model calibration and validation, which showed that ammonia volatilization accounted for 26.5-29.4% of the applied N and N uptake by crop occupied 38.2-44.8%, while N losses via surface runoff, vertical leaching and lateral seepage varied from 5.6-7.7%, 4.0-4.9% to 5.0-5.3% of the applied N, respectively. These observed results were well predicted by our model, indicating that the model performed effectively at quantifying N losses via individual processes in a wide range of urea application rates and benefit for developing water and fertilizer management strategies for near-trench paddy fields.

Functional MR imaging of the spinal cord in cervical spinal cord injury patients by acupuncture at LI 4 (Hegu) and LI 11(Quchi)

PURPOSE

To investigate the cervical spinal cord mapping on acupuncture at LI 4 (Hegu) and LI 11 (Quchi) by using 'Signal Enhancement by Extravascular water Protons' (SEEP)-fMRI, and to establish the response of using acupuncture in the cervical spinal cord. This research may provide some laboratory evidences from the acupuncture treatment on the cervical spinal cord of injuried patients.

METHODS

Seven healthy volunteers (healthy group) and three cervical spinal cord injury patients (injury group) were underwent low-frequency electrical stimulation at LI 4 and LI 11. Meanwhile, a single-shot fast spin-echo (SSFSE) sequence was used to perform functional MR imaging on a 1.5 T GE Signa MR system. The signals from the cervical spinal cord activated was measured both in sagittal and transverse imaging planes and then analyzed by AFNI (Analysis of Functional Neuroimages) system.

RESULTS

It was found that in the sagittal view, two groups had an fMRI response in the cervical spinal cord after given acupuncture treatments at LI 4 and LI 11. The localizations of the segmental fMRI activation were focused at C6 and C2 cervical spinal cord level. In the transverse imaging plane, significant fMRI responses could be measured from the four of seven healthy volunteers and from two of three cervical spinal cord injury patients. They were located at C6/7 segments. The cross-sectional localization of the activity measured in the spinal cord was most in terms of the ipsilateral posterior direction. The signal amplitude varied mainly between 6.8%17.8%. However, the difference found between the two groups had no statistical meaning.

CONCLUSION

The fMRI technique had detected an activation focused at C6 and C2 cervical spinal cord levels by use of acupuncture at LI 4 and LI 11 on a 1.5T GE clinical system. This proved that the meridians and points are found to be in existence. The fMRI can be used as a harmless research method to discuss the mechanisms of acupuncture as well as study the mechanisms of spinal cord diseases. It can be used to direct or monitor the related therapy on the spinal cord injury patients.

Spin-dependent variable range hopping and magnetoresistance in Ti(1-x)Co(x)O(2) and Zn(1-x)Co(x)O magnetic semiconductor films

Magnetic transport properties in Ti(1-x)Co(x)O(2) and Zn(1-x)Co(x)O magnetic semiconductors have been studied experimentally and theoretically. A linear relation of lnρ versus T(-1/2) (ρ is sheet resistance and T is temperature), which shows different slopes and intersections at different magnetic fields, was observed experimentally in the low temperature range. The spin-dependent variable range hopping model has been proposed by taking into account the electron-electron Coulomb interaction and the spin-spin exchange interaction in the same frame, which can well describe the observed magnetic transport properties in Ti(1-x)Co(x)O(2) and Zn(1-x)Co(x)O magnetic semiconductors.

Up-regulation of RhoB by glucocorticoids and its effects on the cell proliferation and NF-kappaB transcriptional activity

Although there is ample evidence that glucocorticoids (GCs) have an antiproliferative effect on many cell types, the molecular mechanism remains elusive. We reported in our previous study that Dex treatment led to cell growth arrest in a human ovarian cancer cell HO-8910. RhoB, as a member of Rho GTPases, have been implicated to be a negative regulator of cell proliferation. In this study, we provided novel evidence that Dex induced the expressions of small GTPase RhoB mRNA and protein, but not RhoA and RhoC mRNA in a dose- and time-dependent fashion via glucocorticoid receptor (GR). Over-expression of RhoB increased while inhibition of RhoB expression by RNA interference reversed Dex-induced growth arrest, indicating that RhoB signaling is involved in Dex-induced proliferation inhibition. We also presented the novel observation that over-expression or activation of RhoB signaling elevated the basal transcriptional activity of the transcription factor NF-kappaB in HO-8910 cells. Furthermore, elevating RhoB signaling enhanced the inhibitory effect of Dex on NF-kappaB activity, while attenuating RhoB signaling almost abrogated Dex suppression of NF-kappaB signaling, indicating that RhoB pathway is involved in the regulation of NF-kappaB activity and is essential for Dex transcriptional repression on NF-kappaB signaling in HO-8910 cells.

Enhanced dissipation of phenanthrene and pyrene in spiked soils by combined plants cultivation

Polycyclic aromatic hydrocarbons (PAHs), a class of POPs, are widely distributed in the environment. Phytoremediation has long been recognized as a cost-effective method for removal of PAHs pollutants from soil. This study was conducted to investigate the capability of three plant species separately and their combination to promote the degradation of phenanthrene and pyrene in soil. The performance of three plant species, maize, ryegrass and white clover for phenanthrene and pyrene removal was also compared. The result showed that the presence of vegetation significantly enhances the dissipation of phenanthrene and pyrene in the soil environment. This effect was especially marked with maize. At the end of 60 days treatment, phenanthrene and pyrene concentrations in treated soils declined from an initial 52.52 mg kg-1 and 58.19 mg kg-1 to 4.15 mg kg-1 and 6.77 mg kg-1, respectively, indicating that phenanthrene and pyrene was successfully removed by maize. Around 92.10% of phenanthrene and 88.36% of pyrene were removed from soils planted with maize. Within approximately two months experimental period, the dissipation extent showed that the 4-ring pyrene was more recalcitrant than 3-ring phenanthrene. Although the extents did not differ significantly among three tested species, the rates of degradation were different. The maize treatment had the highest rate of contaminant removal after two months, followed by white clover and annual ryegrass. As compare to single plant cultivation, combined plants cultivation significantly enhanced the destruction rate and extent of phenanthrene and pyrene in soils. Around 98.22% of phenanthrene and 95.81% of pyrene were removed from soils planted with maize and ryegrass. This research indicates the potential for phenanthrene and pyrene mineralization in combined plants cultivation, which may be especially useful for phytoremediation of soils contaminated with PAHs.

Analysis of the Relationship Between Nm23-H1 Gene and Human Chronic Myeloblastic Leukemia Using SiRNA

To investigate the relationship between nm23-H1 gene and human chronic myeloblastic leukemia we designed siRNAs which target nm23-H1 gene. According to the principles of designing siRNA, we selected three siRNAs and transfected them into K562 cells by lipofectamine2000. The expression levels of nm23-H1 mRNA were detected by reverse transcriptase polymerase chain reaction after transfection for 24 hours. The expression levels of nm23-H1 protein were assayed by immunocytochemical method after transfection for 48 hours. And after transfection for 24, 48 and 72 hours, cell proliferation was determined by MTT method. Among the three siRNAs, siNM526 can effectively inhibit the expression of nm23-H1 on mRNA and protein levels. The growth of K562 cells was suppressed after transfection of siNM526. These results suggest that low expression level of nm23-H1 in K562 cells inhibited cell proliferation, namely reduced malignant degree of them. Therefore nm23-H1 gene might be a potential target of leukemia treatment.

Effect of pH, ionic strength and fulvic acid on the sorption and desorption of cobalt to bentonite

Humic substances and bentonite have attracted great interest in radioactive waste management. Here the sorption of cobalt on bentonite in the presence and absence of fulvic acid (FA) under ambient conditions was studied. The effects of pH, ionic strength, FA and solution concentrations on cobalt sorption to bentonite were also investigated using batch techniques. The results indicate that the sorption of cobalt is strongly dependent on pH and is independent of ionic strength under our experimental conditions. Surface complexation is considered the main mechanism of cobalt sorption to bentonite. In the presence of FA, little effect of FA on cobalt sorption was found at pH<6; a positive effect of FA on cobalt sorption was found for pH 6-8; and a negative effect of FA on cobalt sorption was found at pH>8. The addition sequences of FA/Co(2+) to the bentonite suspension on the sorption of cobalt to FA-coated bentonite were also studied. The results indicated that the sorption is not influenced by the addition sequences. Some possible mechanisms are discussed.

Inhibition of tumor growth and metastasis in vitro and in vivo by targeting macrophage migration inhibitory factor in human neuroblastoma

Macrophage migration inhibitory factor (MIF) has been defined as a novel oncogene. Our previous results have shown that MIF may contribute to the progression of neuroblastoma by (a) inducing N-Myc expression and (b) upregulating the expression of angiogenic factors. The aim of this study was to test whether tumor growth could be inhibited by reduction of endogenous MIF expression in neuroblastoma and clarify the molecular mechanisms underlying MIF reduction on the control of neuroblastoma growth. We established human neuroblastoma cell lines stably expressing antisense MIF (AS-MIF) cDNA. These stable transfectants were characterized by cell proliferation, gene expression profile, tumorigenicity and metastasis in vitro and in vivo. Decreased MIF expression was observed after transfection with AS-MIF in neuroblastoma cells and downregulation of MIF expression significantly correlated with decreased expression of N-Myc, Ras, c-Met and TrkB at protein level. Affymetrix microarray analysis revealed that expression of IL-8 and c-met was inhibited and neuroblastoma-favorable genes such as EPHB6 and BLU were upregulated in MIF reduced cells. Neuroblastoma cell growth exhibited a nearly 80% reduction in AS-MIF transfectants in vitro. Furthermore, mice in which tumors formed after subcutaneous injection of AS-MIF transfectants showed a 90% reduction in tumor growth compared to control. Metastasis in mice was also suppressed dramatically. Our data demonstrate that targeting MIF expression is a promising therapeutic strategy in human neuroblastoma therapy, and also identifies the MIF target genes for further study.

SRXRF microprobe as a technique for studying elements distribution in Elsholtzia splendens

Elsholtzia splendens is a copper tolerant plant growing in copper mine areas in south of China and accumulates considerable heavy metals in plant tissue. In this study, synchrotron radiation X-ray fluorescence spectroscopy (SRXRF) microprobe was used to study the Cu and other elements distribution in E. splendens. The element (P, S, Cl, K, Ca, Mn, Fe, Cu, Zn) in the leaf epidermis and cross-sections of the stem and leaf could be checked by SRXRF which was considered a sensitive technique for trace element analysis. The highest Cu levels were measured in the vascular tissues of stem and petiole, while Cu levels in mesophyll were higher than in leaf epidermis. The levels of most elements were not higher in trichomes than in other tissues. It seems that the celluar compartmentation of heavy metals in epidermis and epidermal trichomes was not the general feature of all plants. There was a significant correlation between Cu and P, S, Ca in distribution, which suggested P, S, and Ca played an important role in Cu accumulation of E. splendens. Based on the significant correlation between Cu and elements Mn, Fe, and Zn in distribution, it seemed that Cu, Mn, Fe, and Zn could be transported by the same transporters with a broad substrate range.

Manganese uptake and accumulation by the hyperaccumulator plant Phytolacca acinosa Roxb. (Phytolaccaceae)

The perennial herb Phytolacca acinosa Roxb. (Phytolaccaceae), which occurs in Southern China, has been found to be a new manganese hyperaccumulator by means of field surveys on Mn-rich soils and by glasshouse experiments. This species not only has remarkable tolerance to Mn but also has extraordinary uptake and accumulation capacity for this element. The maximum Mn concentration in the leaf dry matter was 19,300 microg/g on Xiangtan Mn tailings wastelands, with a mean of 14,480 microg/g. Under nutrient solution culture conditions, P. acinosa could grow normally with Mn supplied at a concentration of 8000 micromol/l, although with less biomass than in control samples supplied with Mn at 5 micromol/l. Manganese concentration in the shoots increased with increasing external Mn levels, but the total mass of Mn accumulated in the shoots first increased and then decreased. At an Mn concentration of 5000 micromol/l in the culture solution, the Mn accumulation in the shoot dry matter was highest (258 mg/plant). However, the Mn concentration in the leaves reached its highest value (36,380 microg/g) at an Mn supply level of 12,000 micromol/l. These results confirm that P. acinosa is an Mn hyperaccumulator which grows rapidly, has substantial biomass, wide distribution and a broad ecological amplitude. This species provides a new plant resource for exploring the mechanism of Mn hyperaccumulation, and has potential for use in the phytoremediation of Mn-contaminated soils.

RH locus contraction in a novel Dc-/D-- genotype resulting from separate genetic recombination events

BACKGROUND

The rare phenotypes Dc- and D-- lack the expression of E/e and CcEe antigens, respectively; their cotransmission in a single family has not been reported.

STUDY DESIGN AND METHODS

Six members of a Chinese family with two exhibiting the Dc- phenotype were studied using standard serologic methods. Rh genotypes were analyzed by Southern blot, and RH loci, by exon PCR. Rh transcripts were characterized by gene-specific RT-PCR and sequencing.

RESULTS

Although Rh typing detected two members as Dc- homozygotes, RFLP analysis and exon PCR showed them to be Dc- heterozygotes with a partial deletion of RHCE. cDNA sequencing showed the expression in the family of normal RHD and RHCe as well as hybrid transcripts, RHD(1-9)/RHCE(10) and RHCE(1-3)/RHD(4-10). Thus, the Dc- members had the genotype of Dc-/ D-- and expressed both hybrid genes that were inherited from their parents, respectively.

DISCUSSION

This is the first demonstration in a family that the Dc- and D-- complexes neither are linked with a normal RHD or RHCE gene. The segregation of these two different hybrid genes with single break points suggests their independent genetic origin and provides molecular insights into the dynamic nature of genomic rearrangements leading to RH locus contraction.

Deletion of arginine codon 229 in the Rhce gene alters e and f but not c antigen expression

BACKGROUND

Rh CcEe antigens occur as ce, Ce, cE, or CE alleles in the RBC membrane. Their epitope structures and the location of their cis interacting products remain to be defined.

MATERIALS AND METHODS

A rare blood sample from a white male whose parents are first cousins was identified. Hemagglutination was performed using standard methods. RH structure and genotype was assessed by Southern blots. Rh transcripts were obtained by gene-specific RT-PCR and sequenced. The mutation was verified by genomic PCR assays.

RESULTS

The donor's RBCs typed D+C-c+E-e-f(Rh6)- with a normal c dose, suggesting the Dc- phenotype. Further tests revealed a weak and qualitatively altered e expression. Southern blots indicated a genotype of Dce/dce without other gross changes. RT-PCR detected a triplet deletion (Delta685AGA687) in the Rhce gene that specifies codon 229 for arginine (Arg229). Sequencing of the region around the mutated exon 5 confirmed the donor to be homozygous for the AGA deletion.

DISCUSSION

Arg229 is invariant on external loop 4 and close to the Ala226Pro change specific for e/E polymorphism. The qualitative and quantitative alteration of e antigen defines Arg229 as a crucial component for e/E epitope presentation. Given a normal dose of c antigen, the disruption of f (Rh6) by Arg229 deletion suggests that external loop 4 is a major structural element contributing to the expression of RHCE cis interacting antigenic products.

Hydrogen-based tubular catalytic membrane for removing nitrate from groundwater

A porous tubular ceramic membrane coated with palladium-cupper (Pd-Cu) catalyst on its surface was prepared and evaluated for catalytic reduction of nitrate from groundwater. Nitrate reduction activity and selectivity with the catalytic membrane were compared with Pd-Cu/Al2O3 catalyst particles. The catalytic membrane reactor exhibited a better selectivity by enabling an effective control of hydrogen gas, thus minimizing ammonium production. No leaching of palladium and copper into aqueous phase was observed, thereby indicating a high chemical stability of the metallic ions on the carrier support. This was also evidenced by the X-ray photoelectron spectroscopy (XPS) profiles of fresh and used catalysts, which showed no significant difference in surface compositions. Due to its higher selectivity in nitrate reduction and better flexibility in terms of operating conditions, the tubular catalytic ceramic membrane could be useful in removing nitrate from groundwater.

S-Nitrosoglutathione-induced mouse thymocyte apoptosis studied by fluorescence near-field scanning optical microscopy

This study is an attempt to deeply understand the mechanisms ensuring self-tolerance of T cells via clonal deletion of thymocytes and exploring T lymophocyte homeostasis by observing the apoptosis of single mouse thymocyte induced by S-nitrosoglutathione (GSNO, a nitric oxide donor) using fluorescence near-field scanning optical microscopy (NSOM) in illumination mode. The GSNO-induced thymocytes were stained with propidium iodide containing 0.01% Triton X-100 and excited with light of 488 nm and the emitting fluorescence at 525 nm. According to the NSOM fluorescence image and the simultaneously obtained topography image, the feature of mouse thymocyte apoptosis was characterized by scattering pattern of the fluorescence spots with the size 0.2-2.1 micro m at the full width at half-maximum of fluorescence intensity 78-80 kHz in the GSNO-treated thymocyte nucleus. Whereas there is no fluorescence from the untreated thymocyte. The intensity of the fluorescence from the dexamethasone-treated thymocyte was much stronger than that from GSNO-induced thymocytes. Furthermore, the fluorescence distribution in the latter were concentrated in the nucleus. Those results also demonstrate the advantages of NSOM such as high spatial resolution and the topography of biology samples.

The role of citric acid on the phytoremediation of heavy metal contaminated soil

Adsorption and hydroponics experiments were conducted to study the role of citric acid on the phytoremediation of heavy metal contaminated soil. The results show that addition of citric acid decreased the adsorption of both lead and cadmium, such an effect was bigger for cadmium than for lead. The decrease in the adsorption of Pb and Cd was mainly due to a decrease of pH in the presence of citric acid. The presence of citric acid could alleviate the toxicity of Pb and Cd to radish, and stimulate their transportation from root to shoot. The studies of heavy metal forms using sequential extraction demonstrated that lead was mainly existed as FHAC (a lower bioavailable form) in the root, while F(HCl) was the dominant form in the leaf. The addition of citric acid to the soil changed the concentration and relative abundance of all the forms. The detoxifying effect of citric acid to Pb in shoots might result from the transformation of higher toxic forms into lower toxic forms. Cadmium was mainly present as F(NaCl), therefore, it had higher toxicity than lead. The addition of citric acid increased the abundance of F(H2O) + F(NaCl), indicating that citric acid treatment could transform cadmium into more transportable forms.

Rapid degradation of butachlor in wheat rhizosphere soil

The degradative characteristics of butachlor in non-rhizosphere, wheat rhizosphere, and inoculated rhizosphere soils were measured. The rate constants for the degradation of butachlor in non-rhizosphere, rhizosphere, and inoculated rhizosphere soils were measured to be 0.0385, 0.0902, 0.1091 at 1 mg/kg, 0.0348, 0.0629, 0.2355 at 10 mg/kg, and 0.0299, 0.0386, 0.0642 at 100 mg/kg, respectively. The corresponding half-lives for butachlor in the soils were calculated to be 18.0, 7.7, 6.3 days at 1 mg/kg, 19.9, 11.0, 2.9 days at 10 mg/kg, and 23.2, 18.0, 10.8 days at 100 mg/kg, respectively. The experimental results show that the degradation of butachlor can be enhanced greatly in wheat rhizosphere, and especially in the rhizosphere inoculated with the bacterial community designated HD which is capable of degrading butachlor. It could be concluded that rhizosphere soil inoculated with microorganisms-degrading target herbicides is a useful pathway to achieve rapid degradation of the herbicides in soil.

Effect of cadmium on nodulation and N2-fixation of soybean in contaminated soils

The effects of cadmium stress on nodulation, N2-fixation capabilities of the root nodule, the change in ultrastructure of the root nodule, soybean growth, and the distribution of cadmium in plants were studied. The results obtained show that the nodulation of soybean roots was greatly inhibited by the addition of Cd, especially at the addition level of 10 and 20 mg kg(-1) soil. The inhibition of plant growth, especially the root growth, increased as the cadmium concentration increased, with deleterious effects observed for the roots. The weight ratio of soybean root/leaf decreased as the Cd concentration increased, which might explain the reason for nodulation decreases. The results also indicate that N2-fixation of root nodule was stimulated to some extent at the low levels of Cd addition, but decreased sharply with further increase of the Cd concentration. High Cd levels were also associated with changes in the ultrastructure of root nodule, in which the effective N2-fixing area was reduced and the N2-fixing cells in the area also reduced. In addition, the results also reveal that the content of Cd in different parts of the plants was as follows: roots >> stems > seeds, indicating that the accumulation of Cd by roots is much larger than that by any other part of the soybean plant, and might cause deleterious effects to root systems.