Polyethyleneimine-coated MXene quantum dots improve cotton tolerance to Verticillium dahliae by maintaining ROS homeostasis.

Verticillium dahliae is a soil-borne hemibiotrophic fungal pathogen that threatens cotton production worldwide. In this study, we assemble the genomes of two V. dahliae isolates: the more virulence and defoliating isolate V991 and nondefoliating isolate 1cd3-2. Transcriptome and comparative genomics analyses show that genes associated with pathogen virulence are mostly induced at the late stage of infection (Stage II), accompanied by a burst of reactive oxygen species (ROS), with upregulation of more genes involved in defense response in cotton. We identify the V991-specific virulence gene SP3 that is highly expressed during the infection Stage II. V. dahliae SP3 knock-out strain shows attenuated virulence and triggers less ROS production in cotton plants. To control the disease, we employ polyethyleneimine-coated MXene quantum dots (PEI-MQDs) that possess the ability to remove ROS. Cotton seedlings treated with PEI-MQDs are capable of maintaining ROS homeostasis with enhanced peroxidase, catalase, and glutathione peroxidase activities and exhibit improved tolerance to V. dahliae. These results suggest that V. dahliae trigger ROS production to promote infection and scavenging ROS is an effective way to manage this disease. This study reveals a virulence mechanism of V. dahliae and provides a means for V. dahliae resistance that benefits cotton production.

The mother-daughter Shared Agency in Weight Management Scale (SAWMS): development, validation, and implications for body dissatisfaction.

BACKGROUND: Much research suggests that mothers play an important role in shaping daughters' body image, yet less is known about how mother-daughter relationship dynamics in weight management affect daughters' body dissatisfaction. The current paper described the development and validation of the mother-daughter Shared Agency in Weight Management Scale (SAWMS) and examined its associations with daughter's body dissatisfaction. METHODS: In Study 1 (N = 676 college students), we explored the factor structure of the mother-daughter SAWMS and identified three processes (control, autonomy support, and collaboration) whereby mothers work with daughters in weight management. In Study 2 (N = 439 college students), we finalized the factor structure of the scale by conducting two CFAs and assessing the test-retest reliability of each subscale. In Study 3 (same sample as Study 2), we examined the psychometric properties of the subscales and their associations with daughters' body dissatisfaction. RESULTS: Combining results from EFA and IRT, we identified three mother-daughter dynamics in weight management-maternal control, maternal autonomy support, and maternal collaboration. However, based on various empirical results indicating poor psychometric properties of the maternal collaboration subscale, we removed it from the mother-daughter SAWMS and only evaluated the psychometric properties of the remaining two subscales (i.e., control and autonomy support). They explained a significant amount of variance in daughters' body dissatisfaction over and above the effect of maternal pressure to be thin. Maternal control was a significant and positive predictor of daughters' body dissatisfaction; maternal autonomy support was a significant and negative predictor. CONCLUSIONS: Results suggested that maternal control in weight management was associated with daughters' increased body dissatisfaction, whereas maternal autonomy support in weight management was associated with daughters' lower body dissatisfaction. These specific ways in which mother work with daughters in weight management provide nuances in understanding young women's body dissatisfaction. Our SAWMS offers new ways to examine body image among young women through the mother-daughter relationship dynamics in weight management.

The current study described the procedure of developing a new measurement­the mother­daughter Shared Agency in Weight Management Scale (SAWMS). This scale aims to measure the different ways in which mothers work with their cisgender daughters in weight management. Based on self-reported survey data from cisgender female college students, we identified two ways whereby mothers work with their daughters in weight management­maternal control and maternal autonomy support. To better understand these mother­daughter dynamics, we also examined their relations with daughter's body dissatisfaction. We found that daughters whose mothers were more controlling when it comes to weight management reported higher levels of body dissatisfaction. On the other hand, daughters whose mothers were more autonomy-supportive in weight management reported lower levels of body dissatisfaction. Our results have important implications for understanding how mother­daughter relationship dynamics in weight management may contribute to the development of body image and perceptions among young women.

Responding to Children's Diverse Gender Expression: Validation of a Parent-Report Measure of Gender-Related Conditional Regard.

Epidemiological studies suggest that more youth are identifying as gender expansive (e.g., transgender, gender nonconforming) than ever before. However, due to stressors like discrimination, gender minorities remain at significantly higher risk for mental and physical health problems than their cisgender peers. While initial research has shown that parental support of youth's minority gender identities may be protective, further research is needed regarding specific parenting practices and their impact on children. We propose that parental conditional regard-the selective provision of warmth and esteem when children's behavior conforms to parental standards or values - may be a critical component of parenting behaviors that predicts maladaptation in gender expansive children. Across three studies involving parents of cisgender and gender expansive children ages 3-15 (Study 1: N = 601, community sample; Study 2: N = 793, parents of gender expansive and cisgender children; Study 3, same sample as in Study 1), we describe the development of a novel measure of parental conditional regard for gender expression and test its validity and reliability. Finally, we demonstrate that conditional regard for gender expression is distinct from existing conditional regard measures, and is uniquely associated with children's psychopathology.

The relative importance of parent-child dynamics and minority stress on the psychological adjustment of LGBs in China.

This cross-sectional study examined how minority stress (i.e., internalized homonegativity, self-concealment, and rejection sensitivity) and positive parent-child relationship dynamics (i.e., respect for parents and perceived parental support for sexual orientation) were associated with the psychological adjustment of lesbian, gay, and bisexual (LGB) individuals in China. Based on survey responses from 277 self-identified Chinese LGB young adults, results from structural equation modeling showed that minority stress was not a significant predictor of psychological maladjustment, whereas respect for parents and perceived parental support for sexual orientation were associated with positive psychological adjustment. Tests of gender differences partially confirmed whether Confucian traditions may burden sexual minority men more than women. Gender differences were found in the correlations between minority stress and each measure of positive parent-child relationship dynamics. However, the associations between independent variables and psychological maladjustment were not different between men and women in the sample. Our results suggest that culture-specific variables, such as parent-child factors within the context of China, may be especially important when working with LGB individuals in research and clinical practice. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Ultraviolet-enhanced wettability and bioactivity of self-organized TiO2 nanotube layer.

TiO2 nanotube layers were prepared by anodic oxidation of commercial pure Ti in aqueous solutions containing 1 M (NH4)2SO4 and 0.15 M NH4F at 20 V for 2 h. The as-anodized layers were annealed at 450 degrees C for 3 h, and a part of the annealed layers were subsequently irradiated by Ultraviolet (UV) light in air for 2 h at room temperature. Hydrophilicity and the apatite-forming ability of TiO2 nanotube layers were evaluated. The results show that the as-anodized layer consists of self-organized TiO2 nanotubes with amorphous structure, which transforms to anatase after annealing at 450 degrees C for 3 h. The annealing treatment of the nanotube layer can significantly enhance its hydrophilicity and bioactivity. Furthermore, UV irradiation of the annealed TiO2 nanotube layer does not alter its surface morphology and phase component, however, can improve hydrophilicity and bioactivity. The enhanced hydrophilicity and bioactivity are thought to result from the abundant basic Ti-OH groups on the UV-irradiated TiO2 nanotube layer.

Biomedical research of novel biodegradable copoly(amino acid)s based on 6-aminocaproic acid and L-proline.

The biomedical properties of novel biodegradable copoly(amino acid)s based on 6-aminocaproic acid and L-proline were analyzed in this article. The cytotoxicity of the copolymer films was tested in vitro using human embryonic kidney (HEK) 293 cells. The cell proliferation, cell cycle, cell apoptosis, and hemolysis of the polymers were also investigated. No significant cytotoxic response was detected statistically by cytotoxicity assay, and the results of cell apoptosis and cell cycle showed that there were no statistically significant differences in them. Generally, the cells spread and grew well on polymer film. Meanwhile, the extent of hemolysis on the polymers was acceptable. Evaluation of cytotoxicity by cell cycle and apoptosis as a supplementary assay is correspondingly discussed in this article.

Evaluation of hepatic-metastasis risk of colorectal cancer upon the protein signature of PI3K/AKT pathway.

Liver is the most common organ of colorectal cancer (CRC) metastasis, and hepatic metastasis (HM) is regulated by complex protein network. Hence, we initiated a proteomic survey to seek interrelated multiplex markers related with HM. A total of 34 unique differential proteins were identified in the primary tumor tissues from 14 CRC patients with/without HM. A differential protein cluster, consisting of 17 proteins throughout PI3K/AKT pathway, was deduced and validated by Western blot. A three-protein signature elicited from the protein cluster, phosphorylated IkappaBalpha, TNFalpha and MFAP3L, was detected by immunohistochemistry on 105 pairs of CRC and normal samples. The positive protein signature was specifically correlated with HM (P < 0.001), and classified the HM risk of CRC patients with high sensitivity (92.85 +/- 4.87%) and specificity (94.94 +/- 2.5%). The high-risk group had significantly decreased overall survival (P < 0.001). Furthermore, RKO and HT29, two colon cancer cells with different expression status of the protein signature, were used to construct the nude mouse model of HM. And the HM occurrence of RKO cell (4/5) was dramatically higher than that of HT29 cell (1/5). Therefore, the protein signature derived from PI3K/AKT pathway is likely a promising multiplex biomarker for HM of CRC.

Proteomic analysis of differential proteins related to the neuropathic pain and neuroprotection in the dorsal root ganglion following its chronic compression in rats.

The aim of the study was to identify the differential protein expressions related to neuropathic pain and neuroprotection in the dorsal root ganglion (DRG) following chronic compression of DRG (CCD) in rats. We conducted a proteomics study of L(4) and L(5) DRG after CCD for 28 days. A total of 98 protein spots were detected with significant changes in their expression levels after CCD and 15 protein spots were identified by the matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. Of these proteins, annexin A2, protein kinase C epsilon (PKCepsilon), glyceraldehyde-3-phosphate dehydrogenases (GAPDH), and heat shock protein 70 (HSP70) were up-regulated significantly compared with the normal control. These four proteins and p11, which was annexin A2 light chain, were further examined by Western blotting. The results of Western blotting and the proteomic analysis showed consistent data. Moreover, real-time quantitative RT-PCR experiments indicated that CCD-induced increase in protein levels was associated with an up-regulation of annexin A2 and PKCepsilon gene expression. In conclusion, this study highlights the molecular process in DRG underlying neuropathic pain. CCD is associated with the up-regulation of annexin A2 and PKCepsilon and their related genes. The up-regulation of GAPDH and HSP70 suggests that there exist concurrent processes of nervous injury and neuroprotection in the course of neuropathic pain.

Comparative analysis of the protein profiles from primary gastric tumors and their adjacent regions: MAWBP could be a new protein candidate involved in gastric cancer.

The study of tumor biomarkers is generally facilitated by the adoption of proteomic strategies. With limitations of techniques and individual varieties of biological samples, the biomarkers for gastric cancer (GC) have not reached a common agreement derived from the proteomic investigations. Herein, we reported a new set of data for screening the biomarkers from the gastric tissues, on the basis of the proteomic strategy developed in our laboratory. Ten pairs of the clinic samples were collected and treated with protein extraction. The gastric proteins were well-resolved by 2-DE, and the GC-associated proteins were identified by MALDI-TOF/TOF MS following image analysis, including 12 up-regulated and 13 down-regulated unique ones. MAWBP was found to be one of the new GC proteins which appeared with lower expression in the GC tissues. We expanded a systematical examination to deeply pursue the relevance between MAWBP and GC. Quantitatively, we measured the expression of MAWBP with Western blot and Real-Time PCR. Extendedly, we estimated the existence of MAWBP with immunohistochemical staining in a large number of the GC cases. Specifically, we inquired whether MAWD, a protein with high affinity to MAWBP, could coexpress and interact with MAWBP in vivo. On the basis of all the results, we concluded that MAWBP could be a new GC-related protein even though its physiological roles remain unexplored.

A controversial tumor marker: is SM22 a proper biomarker for gastric cancer cells?

SM22, a dominant protein in smooth muscle cells (SMCs), has been widely reported to be abnormally expressed in many solid tumors. However, the expression patterns of SM22 are not consistent in all tumors, not even in the same ones. Whether SM22 should be considered a tumor biomarker is still debated in different laboratories. Herein, we have carried out a systematical investigation to validate SM22 expression in the primary tissues of gastric cancer (GC). Of eight cases, seven samples were found in the elevated expression of SM22 proteins through proteomic analysis. The observation was further verified by the approaches of Western blotting and quantitative RT-PCR. Surprisingly, the results achieved from tissue microarray in 126 GC cases appeared contrary to the proteomic conclusion, in which the highly expressed SM22 was mainly found in smooth muscle layers, blood vessels, and myofibroblasts. This suggested that the increased abundance of SM22 in the cancerous regions was not caused by the presence of the GC cells. Furthermore, the expression of SM22 was measured in different GC cell lines and SMCs with Western blotting and quantitative RT-PCR. The results revealed that SM22 expression in SMCs was dramatically higher than that of the GC cells, which indicates that SM22 is unlikely to be a proper biomarker for GC. Instead, it can be considered a potential indicator for the abnormal developments of smooth muscles, blood vessels, or myofibroblasts triggered by tumorigenesis.

The proteomic alterations of Thermoanaerobacter tengcongensis cultured at different temperatures.

Thermoanaerobacter tengcongensis, one of many thermophilic organisms, survives harsh living conditions in temperatures ranging from 50 to 80 degrees C. In this comprehensive analysis, we present a robust approach, 2-DE and MALDI-TOF MS, to compare and identify the bacterial proteins responding to the temperature stress. In total, 164 spots of 2-DE were found with the significant changes in spot volume at three culture temperatures, 55, 75, and 80 degrees C, respectively; furthermore, 87 unique proteins were characterized by MS. Our results reveal that the electrophoretic images of the bacterial proteins, extracted from two culture temperatures (55 and 75 degrees C), had similar patterns; however, the bacteria cultured at 80 degrees C had dramatically decreased their spot volumes. Additionally, the temperature-sensitive proteins are broadly divided into two groups: specific expression at certain temperatures and consistent changes of expression responsive to temperature. For instance, three proteins closely related with redox regulation, dihydrolipoamide acyltransferase, NADH:ubiquinone oxidoreductase, and ferredoxin, were only detected in the bacteria cultured at 55 degrees C. Whereas, two chaperonins, GroES and GroEL, were found to show a consistent increase during the elevated temperatures with the determinations, either by MS or Western blot. The proteomic information, thus expedites our understanding of the molecular mechanisms regarding how thermophilic bacteria adapt to the alterations in living environment.

Proteomic and transcriptomic analysis of rice mature seed-derived callus differentiation.

Callus differentiation is a key developmental process for rice regeneration from cells. To better understand this complex developmental process, we used a 2-D gel electrophoresis approach to explore the temporal patterns of protein expression at the early stages during rice callus differentiation. This global analysis detected 60 known proteins out of 79 gel spots identified by MS/MS, of which many had been shown to play a role in plant development. Two new proteins were revealed to be associated with the callus differentiation and have been confirmed by Western blot analysis. The results of proteomics experiments were further verified at the mRNA level using microarray and real-time PCR. Comparison of the differentially expressed protein levels with their corresponding mRNA levels at the two callus early differentiation stages showed a good correlation between them, indicating that a substantial proportion of protein changes is a consequence of changed mRNA levels, rather than post-transcriptional effects during callus differentiation, though microarray revealed more expression changes on RNA levels. These findings may contribute to further understanding of the mechanisms that lead to callus differentiation of rice and other plants as well.

Identification of phosphorylation sites in the nucleocapsid protein (N protein) of SARS-coronavirus.

After decoding the genome of SARS-coronavirus (SARS-CoV), next challenge is to understand how this virus causes the illness at molecular bases. Of the viral structural proteins, the N protein plays a pivot role in assembly process of viral particles as well as viral replication and transcription. The SARS-CoV N proteins expressed in the eukaryotes, such as yeast and HEK293 cells, appeared in the multiple spots on two-dimensional electrophoresis (2DE), whereas the proteins expressed in E. coli showed a single 2DE spot. These 2DE spots were further examined by Western blot and MALDI-TOF/TOF MS, and identified as the N proteins with differently apparent pI values and similar molecular mass of 50 kDa. In the light of the observations and other evidences, a hypothesis was postulated that the SARS-CoV N protein could be phosphorylated in eukaryotes. To locate the plausible regions of phosphorylation in the N protein, two truncated N proteins were generated in E. coli and treated with PKCα. The two truncated N proteins after incubation of PKCα exhibited the differently electrophoretic behaviors on 2DE, suggesting that the region of 1-256 aa in the N protein was the possible target for PKCα phosphorylation. Moreover, the SARS-CoV N protein expressed in yeast were partially digested with trypsin and carefully analyzed by MALDI-TOF/TOF MS. In contrast to the completely tryptic digestion, these partially digested fragments generated two new peptide mass signals with neutral loss, and MS/MS analysis revealed two phosphorylated peptides located at the "dense serine" island in the N protein with amino acid sequences, GFYAEGSRGGSQASSRSSSR and GNSGNSTPGSSRGNSPARMASGGGK. With the PKCα phosphorylation treatment and the partially tryptic digestion, the N protein expressed in E. coli released the same peptides as observed in yeast cells. Thus, this investigation provided the preliminary data to determine the phosphorylation sites in the SARS-CoV N protein, and partially clarified the argument regarding the phosphorylation possibility of the N protein during the infection process of SARS-CoV to human host.

A proteomic investigation into a human gastric cancer cell line BGC823 treated with diallyl trisulfide.

Garlic is generally used as a therapeutic reagent against various diseases worldwide. Although a great effort is made to understand the pharmaceutical mechanisms of garlic and its derivatives, there are many mysteries to be uncovered. Using proteomic means, herein we have systematically studied the responses of protein expression in BGC823 cells, a gastric cancer cell line, induced by diallyl trisulfide (DATS), a major component of garlic derivatives. A total of 41 unique proteins in BGC823 were detected with significant changes in their expression levels corresponding with DATS administration. Of these proteins, five typical ones, glutathione S-transferase-pi (GST-pi), voltage-dependent anion channel-1 (VDAC-1), Annexin I, Galectin and S100A11, were further examined by Western blotting, resulting in coincident data with the proteomic evidence. Moreover quantitative real-time RT-PCR experiments offered dynamic data of mRNA expression, indicating the responses of Annexin I and GST-pi expression within a short period after DATS treatment. Interestingly, approximately 50% of DATS-sensitive proteins (19/41) in BGC823 are tightly associated with apoptotic pathways. These proteomic results presented, therefore, provide additional support to the hypothesis that garlic is a strong inducer of apoptosis in tumor cells.

Pedigree analysis of an elite rice hybrid using proteomic approach.

The definition of dominance or epistasis is generally on the basis of a descriptive characterization for these crops in the field, such as yield per hectare and the weight of grain. Since these trait examinations lack molecular information, how to precisely predict the phenotypic changes in filial generation is still a problem in heterosis studies. For rice, the genetic information caused by hybridization can be archived through analyzing of proteomes of rice seeds. Differential analysis of proteomes was introduced for the rice seeds of three cultivars, 9311, PA64S and LYP9, an elite rice hybrid from cross between 9311 and PA64S. In the three rice endosperms, the expression profiles of proteins were similar with the stained spots of 47 +/- 1, 46 +/- 0.6 and 44 +/- 0.6, for 9311, PA64S and LYP9, respectively; however, the number of proteins expressed in the rice embryos was significantly increased with the stained spots of 395.3 +/- 12.9, 350 +/- 9.2, and 389.3 +/- 16.4, for 9311, PA64S and LYP9, respectively. Importantly, the image comparisons and protein identifications have revealed in significantly different embryo protein spots among the three rice cultivars. By carefully analyzing these different 2-DE spots, many of them from the three embryos were shown to display a mirrored relationships between parents and the first filial generation. Furthermore, all of stained spots in LYP9 embryo were found on the 2-DEs from its parents, indicating that there was a genetic linkage. These results suggest that proteomic approach is able to serve pedigree analysis and functional prediction for new rice breeds.

Proteomic changes in rice leaves during development of field-grown rice plants.

Of the numerous factors affecting rice yield, how solar radiation is transformed into biomass through rice leaves is the most important. We have analyzed proteomic changes in rice leaves collected from six different developing stages (vegetative to ripening). We studied protein expression profiles of rice leaves by running two-dimensional gel electrophoresis. Differential protein expression among the six phases were analyzed by image analysis, which allowed the identification of 49 significantly different gel spots. The spots were further verified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry, in which 89.8% of them were confirmed to be rice proteins. Finally, we confirmed some of the interesting rice proteins by immunoblotting. Three major conclusions can be drawn from these experimental results. (i) Protein expression in rice leaves, at least for high or middle abundance proteins, is attenuated during growth (especially some chloroplast proteins). However, the change is slow and the expression profiles are relatively stable during rice development. (ii) Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), a major protein in rice leaves, is expressed at constant levels at different growth stages. Interestingly, a high ratio of degradation of the RuBisCO large subunit was found in all samples. This was confirmed by two approaches, mass spectrometry and immunoblotting. The degraded fragments are similar to other digested products of RuBisCO mediated by free radials. (iii) The expression of antioxidant proteins such as superoxide dismutase and peroxidase decline at the early ripening stage.

[Relationship between acute dipterex poisoning and oxidative stress and free radical damage].

OBJECTIVE: To study relationship between acute dipterex poisoning and oxidative stress and free radical damage. METHODS: Eighty-two patients with acute dipterex poisoning (ADPP) and ninety-two healthy adult volunteers (HAV) were enrolled in the study with randomized controlled trial design. Plasma levels of vitamin C (VC) and vitamin E (VE), as well as level of lipoperoxide (LPO) and activities of superoxide dismutase (SOD) and acetylcholinesterase (AChE) in the red blood cells (RBC), were determined by spectrophotometry. RESULTS: Levels of VC and VE, and activities of SOD and AChE were (37.35 +/- 9.98) micromol/L, (16.57 +/- 4.54) micromol/L, (1 785 +/- 154) U/g Hb and (213.1 +/- 57.6) U/g Hb, respectively, in the ADPP group, significantly lower than those in the HAV group, (55.34 +/- 15.98) micromol/L, (25.66 +/- 7.24) micromol/L, (2 124 +/- 185) U/g Hb and (305.3 +/- 83.6) U/g Hb, respectively. Plasma level of LPO was (35.20 +/- 5.29) nmol/g Hb in the ADPP group, significantly higher than that in the HAV group, (27.87 +/- 4.66) nmol/g Hb. Partial correlation analysis suggested that there existed negative correlation between activity of AChE in the RBC and plasma level of LPO (r = -0.274, P = 0.013) and positive correlation between activity of AChE in the RBC and plasma levels of VC and VE, and activity of SOD in the RBC (r = 0.333, P = 0.002, r = 0.269, P = 0.015 and r = 0.248, P = 0.026, respectively) in the ADPP, adjusted for age. Coefficient of reliability alpha was 0.682 (P < 0.001), with a standardized alpha of 0.868 (P < 0.001). CONCLUSION: There exist severe oxidative stress and free radical damage in patients with acute dipterex poisoning.

Proteomic characterization of two snake venoms: Naja naja atra and Agkistrodon halys.

Snake venom is a complex mixture of proteins and peptides, and a number of studies have described the biological properties of several venomous proteins. Nevertheless, a complete proteomic profile of venom from any of the many species of snake is not available. Proteomics now makes it possible to globally identify proteins from a complex mixture. To assess the venom proteomic profiles from Naja naja atra and Agkistrodon halys, snakes common to southern China, we used a combination strategy, which included the following four different approaches: (i) shotgun digestion plus HPLC with ion-trap tandem MS, (ii) one-dimensional SDS/PAGE plus HPLC with tandem MS, (iii) gel filtration plus HPLC with tandem MS and (iv) gel filtration and 2DE (two-dimensional gel electrophoresis) plus MALDI-TOF (matrix-assisted laser desorption ionization-time-of-flight) MS. In the present paper, we report the novel identification of 124 and 74 proteins and peptides in cobra and viper venom respectively. Functional analysis based upon toxin categories reveals that, as expected, cobra venom has a high abundance of cardio- and neurotoxins, whereas viper venom contains a significant amount of haemotoxins and metalloproteinases. Although approx. 80% of gel spots from 2DE displayed high-quality MALDI-TOF-MS spectra, only 50% of these spots were confirmed to be venom proteins, which is more than likely to be a result of incomplete protein databases. Interestingly, these data suggest that post-translational modification may be a significant characteristic of venomous proteins.

The epitope study on the SARS-CoV nucleocapsid protein.

The nucleocapsid protein (N protein) has been found to be an antigenic protein in a number of coronaviruses. Whether the N protein in severe acute respiratory syndrome-associated coronavirus (SARS-CoV) is antigenic remains to be elucidated. Using Western blot and Enzyme-linked Immunosorbent Assay (ELISA), the recombinant N proteins and the synthesized peptides derived from the N protein were screened in sera from SARS patients. All patient sera in this study displayed strong positive immunoreactivities against the recombinant N proteins, whereas normal sera gave negative immunoresponses to these proteins, indicating that the N protein of SARS-CoV is an antigenic protein. Furthermore, the epitope sites in the N protein were determined by competition experiments, in which the recombinant proteins or the synthesized peptides competed against the SARS-CoV proteins to bind to the antibodies raised in SARS sera. One epitope site located at the C-terminus was confirmed as the most antigenic region in this protein. A detailed screening of peptide with ELISA demonstrated that the amino sequence from Codons 371 to 407 was the epitope site at the C-terminus of the N protein. Understanding of the epitope sites could be very significant for developing an effective diagnostic approach to SARS.