Haplotype-resolved gapless genome and chromosome segment substitution lines facilitate gene identification in wild rice.

The abundant genetic variation harbored by wild rice (Oryza rufipogon) has provided a reservoir of useful genes for rice breeding. However, the genome of wild rice has not yet been comprehensively assessed. Here, we report the haplotype-resolved gapless genome assembly and annotation of wild rice Y476. In addition, we develop two sets of chromosome segment substitution lines (CSSLs) using Y476 as the donor parent and cultivated rice as the recurrent parents. By analyzing the gapless reference genome and CSSL population, we identify 254 QTLs associated with agronomic traits, biotic and abiotic stresses. We clone a receptor-like kinase gene associated with rice blast resistance and confirm its wild rice allele improves rice blast resistance. Collectively, our study provides a haplotype-resolved gapless reference genome and demonstrates a highly efficient platform for gene identification from wild rice.

Genome-wide selection and introgression of Chinese rice varieties during breeding.

China is the largest rice-producing country, but the genomic landscape of rice diversity has not yet been clarified. In this study, we re-sequence 1070 rice varieties collected from China (400) and other regions in Asia (670). Among the six major rice groups (aus, indica-I, indica-II, aromatic, temperate japonica, and tropical japonica), almost all Chinese varieties belong to the indica-II or temperate japonica group. Most Chinese indica varieties belong to indica-II, which consists of two subgroups developed during different phases of rice breeding. The genomic segments underlying the differences between these subgroups span 36.32 Mb. The Chinese japonica rice varieties fall into the temperate japonica group, consisting of two subgroups based on their geographical distribution. The genomic segments underlying the differences between these subgroups span 27.69 Mb. These differentiated segments in the Chinese indica varieties span 45 genes with nonsynonymous mutations that are closely related to variations in plant height and grain width. Fifty-four genes with nonsynonymous mutations are associated with the differences in heading date between the two Chinese japonica subgroups. These findings provide new insights into rice diversity in China that will facilitate the molecular breeding.

Overexpression of miR-99a Alleviates Intestinal Mucosal Barrier Injury in Rats with Severe Acute Pancreatitis.

Severe acute pancreatitis (SAP), which is characterized by acute onset and high mortality, is complicated with systemic inflammatory response syndrome. This study investigated the molecular mechanism underlying SAP-induced intestinal mucosal barrier injury. SAP was established in rats by retrograde injection of sodium taurocholate (STC) into biliopancreatic duct. Transfection of miR-99a mimic was conducted 24 h before the SAP establishment. Histological properties of pancreatic and intestinal tissues were observed by hematoxylin-eosin staining. The serum levels of interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, procalcitonin (PCT), endotoxin (ET), and diamine oxidase (DAO) were measured by enzyme-linked immunosorbent assay. The expressions of miR-99a, NADPH oxidase (NOX)4, zonula occludens (ZO)-1, occludin, and claudin-1 in pancreatic and the intestinal tissue were determined by quantitative reverse transcription polymerase chain reaction or Western blot. STC injection damaged pancreatic and intestinal tissues of the rats. During the model construction, the serum levels of IL-1ß, TNF-α, PCT, ET, and DAO were increased, whereas miR-99a expression in pancreatic and intestinal tissues of the rats was decreased. miR-99a mimic alleviated SAP-induced histological abnormality of pancreatic and intestinal tissues; moreover, it reversed the serum levels of IL-1ß, TNF-α, PCT, ET, and DAO increased by SAP, decreased SAP-increased NOX4 expression and increased the expressions of ZO-1, occludin, and claudin-1 previously decreased by SAP in pancreatic and the intestinal tissues. Thus, overexpressed miR-99a could alleviate intestinal mucosal barrier injury in rats with SAP.

A Novel Glycerol Kinase Gene OsNHO1 Regulates Resistance to Bacterial Blight and Blast Diseases in Rice.

Glycerol-induced resistance to various pathogens has been reported in different plants. Glycerol kinase (GK), a vital rate-limiting enzyme that catalyzes glycerol conversion to glycerol-3-phosphate (G3P), participates in responses to both abiotic and biotic stresses. However, its physiological importance in rice defenses against pathogens remains unclear. In this research, quantification analysis revealed that GK levels were significantly induced in rice leaves infected by Xanthomonas oryzae pv. oryzae (Xoo) strain PXO99. A typical GK-encoding gene OsNHO1 was cloned in rice. The transcriptional levels of OsNHO1 were significantly induced by salicylic acid, jasmonic acid, and Xoo-PXO99. Ectopic expression of OsNHO1 partially rescued the resistance to P. s. pv. phaseolicola in the Arabidopsis nho1 mutant. In the overexpressing transgenic rice lines (OsNHO1-OE), the content of GK and the transcriptional level of OsNHO1 were increased and the resistance to bacterial blight and blast was improved, while reduced OsNHO1 expression impaired the resistance in OsNHO1-RNAi lines. The wax contents and expression of the wax synthesis regulatory genes were significantly increased in the overexpression lines but decreased in the OsNHO1-RNAi lines. We then confirmed the interaction partner of OsNHO1 using yeast two-hybrid and bimolecular fluorescence complementation assays. The transcription of the interaction partner-encoding genes OsSRC2 and OsPRs in OsNHO1-RNAi lines was downregulated but upregulated in OsNHO1-OE lines. Thus, we concluded that OsNHO1 provided disease resistance by affecting the wax content and modulating the transcription levels of PR genes.

Mir-421 in plasma as a potential diagnostic biomarker for precancerous gastric lesions and early gastric cancer.

OBJECTIVE: MicroRNA (miR)-421 plays a key role in cancer progression. It has been reported that circulating miR-421may be a potential tumor marker for the diagnosis of several cancers. However, the role of miR-421 in plasma as a potential biomarker in the diagnosis of precancerous gastric lesions (Pre) and early-stage gastric cancer (GC) remains poorly understood. In this study, we investigated miR-421 in plasma as a novel potential biomarker for the detection of precancerous gastric lesions and early-stage (GC). MATERIALS & METHODS: The miRNA content was determined by quantitative real-time polymerase chain reaction (qRT-PCR). MiR-421 content in all subjects was normalized by endogenous miRNA (miR-16). The diagnostic value of miR-421 for Pre and GC was assessed by comparing receiver operating characteristic (ROC) analysis with traditional tumor markers, including CEA, CA125, CA153, CA211 and CA50. The correlation between the expression of miR-421 and the pathological characteristics of Pre and GC was analyzed. RESULTS: Elevated expression of miR-421 in plasma can robustly distinguish the normal population from Pre and GC cases, especially in the early stages of gastric cancer cases (all p < 0.05). The ROC analyses showed that the area under the ROC curve (AUC), sensitivity, accuracy and Youden index of miR-421 were superior to traditional tumor markers (CEA, CA125, CA153, CA211, and CA50) in GC diagnosis, while its specificity was higher than CEA, CA153 and CA50 (all p < 0.05). MiR-421 in plasma had higher AUC value than AFP, CA153, CA211 and CA50 in the diagnosis of Pre (all p < 0.05), while specificity, accuracy and Youden index of miR-421 was only lower than CA211. The efficiency of miR-421 in the diagnosis of GC was significantly higher than that of CA211 and CA50, and it was significantly higher than CA153, CA211 and CA50 in the diagnosis of Pre (all p < 0.05). In addition, up-regulation of miR-421 occurred initially in precancerous gastric lesions as well as in the early stage of GC. CONCLUSIONS: Overexpression of plasma miR-421 is a novel biomarker for the detection of precancerous lesions and early gastric cancer.

MeBIK1, a novel cassava receptor-like cytoplasmic kinase, regulates PTI response of transgenic Arabidopsis.

Cassava bacterial blight is the most destructive disease in cassava, causing a significant reduction in its production. The innate immunity response, which has a broad spectrum and a persistent effect, is the basal defence of plants in response to pathogens. Isolation and identification of innate immune-related genes in cassava will contribute to understanding the disease resistance mechanism. In Arabidopsis, the receptor-like cytoplasmic kinase (RLCK) AtBIK1 is known to be an important signal mediator in pathogen-associated molecular pattern-triggered immunity (PTI) response, forming a signal complex from various receptors including the flagellin receptor FLS2, the chitin receptor CERK1 and the receptor for bacterial EF-Tu EFR (Zhang et al. 2010). In the present study, we selected a candidate receptor-like cytoplasmic kinase gene, MeBIK1, from the cassava genome. MeBIK1 encodes a 409 amino acid polypeptide comprising a typical serine/threonine protein kinase domain, and is located on the cell membrane. MeBIK1 gene expression was significantly increased upon stimulation with flagellin (flg22) and peaked at 1h. In vitro genetic complementation experiment showed that MeBIK1 complemented the reduced pathogen-associated molecular pattern-triggered immunity (PTI) response in Arabidopsis bik1 mutant. Arabidopsis MeBIK1 overexpression lines OX1 demonstrated a strong resistance to Xanthomonas axonopodis pv. manihotis HN01, whereas its sensitivity to Pseudomonas syringae pv. tomato DC3000 was enhanced. The peak level of reactive oxygen species (ROS) burst was reached in different Arabidopsis plants (bik1, OX1 and wild type) at 12min after induction with flg22. However, the OX1 showed significantly higher ROS levels than the control and mutant, whereas the lowest level of ROS burst was found in the bik1 mutant. These results indicate that cassava MeBIK1 has a similar function as Arabidopsis AtBIK1 and improves disease resistance in transgenic Arabidopsis by regulating the PTI response.

GWAS in childhood acute lymphoblastic leukemia reveals novel genetic associations at chromosomes 17q12 and 8q24.21.

Childhood acute lymphoblastic leukemia (ALL) (age 0-14 years) is 20% more common in Latino Americans than non-Latino whites. We conduct a genome-wide association study in a large sample of 3263 Californian children with ALL (including 1949 of Latino heritage) and 3506 controls matched on month and year of birth, sex, and ethnicity, and an additional 12,471 controls from the Kaiser Resource for Genetic Epidemiology Research on Aging Cohort. Replication of the strongest genetic associations is performed in two independent datasets from the Children's Oncology Group and the California Childhood Leukemia Study. Here we identify new risk loci on 17q12 near IKZF3/ZPBP2/GSDMB/ORMDL3, a locus encompassing a transcription factor important for lymphocyte development (IKZF3), and at an 8q24 region known for structural contacts with the MYC oncogene. These new risk loci may impact gene expression via local (four 17q12 genes) or long-range (8q24) interactions, affecting function of well-characterized hematopoietic and growth-regulation pathways.

Overexpressing OsMAPK12-1 inhibits plant growth and enhances resistance to bacterial disease in rice.

Mitogen-activated protein kinases (MAPKs) play important roles in plant growth and development, plant abiotic stresses signalling pathway and plant-pathogen interactions. However, little is known about the roles of MAPKs in modulating plant growth and pathogen resistance. In this study, we found that OsMAPK12-1, an alternatively spliced form of BWMK1 in rice (Oryza sativa L.), was induced by various elicitors, such as jasmonic acid, salicylic acid, melatonin and bacterial pathogens. To further investigate the involvement of OsMAPK12-1 in plant growth and stress responses to bacterial pathogens, we constructed OsMAPK12-1 overexpression and knockdown (RNAi) transgenic rice lines. Interestingly, overexpressing OsMAP12-1 inhibited seed germination and seedling growth. Additionally, the OsMAP12-1-overexpression lines displayed enhanced disease resistance against Xanthomonas oryzae pv. oryzae PXO99 and Xanthomonas oryzae pv. oryzicola RS105, whereas the OsMAPK12-1-RNAi lines were more susceptible to these pathogens than wild type. These results suggest that OsMAPK12-1 plays a negative role in plant growth and positively modulates disease resistance against bacterial blight and streak in rice.

[Distribution of fimA genotype of Porphyromonas gingivalis in Chinese periodontitis patients and its relationship with chronic periodontitis].

OBJECTIVE: To investigate the distribution of fimA genotype of Porphyromonas gingivalis in Chinese periodontitis patients and try to find the relationship between fimA genotype and chronic periodontitis. METHODS: Subgingival plaque samples were collected from 101 periodontitis patients. P. gingivalis 16S rRNA primer and fimA type-specific primer were designed. The distribution of fimA genotype in periodontitis patients was detected by PCR. Clinical periodontal indices (PPD, CAL and BOP) were measured at the sample tooth's six points; namely, the mesio-, mid-, distobuccal and mesio-, mid-, distolingual points. RESULTS: P. gingivalis was detected in 89 periodontitis patients (88.1%). Among them, a single fimA genotype was detected in most subgingival plaque samples (65.1%), and the most prevalent fimA genotype was type II (43.8%), followed by type IV (40.4%); Type II fimA and IV fimA were more frequently detected in mild/moderate periodontitis group and severe periodontitis group. CONCLUSION: The findings indicate that P. gingivalis with type II fimA and IV fimA are more predominant in Chinese periodontitis, and the organisms are involved in the destructive progression of periodontitis in Chinese.

Transcriptome Analysis of Ceriops tagal in Saline Environments Using RNA-Sequencing.

Identification of genes involved in mangrove species' adaptation to salt stress can provide valuable information for developing salt-tolerant crops and understanding the molecular evolution of salt tolerance in halophiles. Ceriops tagal is a salt-tolerant mangrove tree growing in mudflats and marshes in tropical and subtropical areas, without any prior genome information. In this study, we assessed the biochemical and transcriptional responses of C. tagal to high salt treatment (500 mmol/L NaCl) by hydroponic experiments and RNA-seq. In C. tagal root tissues under salt stress, proline accumulated strongly from 3 to 12 h of treatment; meanwhile, malondialdehyde content progressively increased from 0 to 9 h, then dropped to lower than control levels by 24 h. These implied that C. tagal plants could survive salt stress through biochemical modification. Using the Illumina sequencing platform, approximately 27.39 million RNA-seq reads were obtained from three salt-treated and control (untreated) root samples. These reads were assembled into 47,111 transcripts with an average length of 514 bp and an N50 of 632 bp. Approximately 78% of the transcripts were annotated, and a total of 437 genes were putative transcription factors. Digital gene expression analysis was conducted by comparing transcripts from the untreated control to the three salt treated samples, and 7,330 differentially expressed transcripts were identified. Using k-means clustering, these transcripts were divided into six clusters that differed in their expression patterns across four treatment time points. The genes identified as being up- or downregulated are involved in salt stress responses, signal transduction, and DNA repair. Our study shows the main adaptive pathway of C. tagal in saline environments, under short-term and long-term treatments of salt stress. This provides vital clues as to which genes may be candidates for breeding salt-tolerant crops and clarifying molecular mechanisms of salt tolerance in C. tagal. The expression levels of 20 candidate genes measured by RNA-Seq were validated via qRT-PCR. Eighteen genes showed consistent expression patterns in RNA-Seq and qRT-PCR results, suggesting that the RNA-seq dataset was dependable for gene expression pattern analysis.

Effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria in vitro.

BACKGROUND: Cecropin-XJ belongs to cecropin-B, which is the most potent antibacterial peptide found naturally. The aim of this study was to investigate the effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria. METHODS: Four oral cariogenic bacteria (Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus and Actinomyces naeslundii) were chosen for this experiment. The minimal inhibitory concentrations (MICs) and reductive percent of bacterial growth were used to assay the antibacterial activity of cecropin-XJ. Mammalian cytotoxicity of cecropin-XJ was tested with human periodontal membrane fibroblasts by tetrazolium (MTT) colorimetric assay. The bacterial morphological changes induced by cecropin-XJ were examined on scanning electron microscope (SEM). The influence of cecropin-XJ on bacterial adhesion to saliva-coated hydroxyapatite (S-HA) was measured by scintillation counting. RESULTS: The MICs of cecropin-XJ for inhibition of the growth of four bacteria ranged from 4.0 to 42.8 micromol/L with the highest susceptible to A. naeslundii and the lowest susceptible to L. acidophilus. At pH 6.8, 5.5 and 8.2, 1/2 MIC of cecropin-XJ reduced the number of viable bacteria by 40.9%, 67.8% and 32.8% for S. mutans and by 28.1%, 57.2% and 37.9% for L. acidophilus. The activities against S. mutans and L. acidophilus increased at pH 5.5 compared with pH 6.8 (P < 0.01, respectively). In present of 50% saliva, 1/2 MIC of the peptide decreased the direct count of viable cells by 29.2% and 14.4% for S. mutans and L. acidophilus, respectively (P < 0.01 and P > 0.05, respectively), whereas almost no reduction counts were detected in the presence of 20% serum for both bacteria (P > 0.05, respectively). Mammalian cytotoxicity of cecropin-XJ from 1.0 to 100 micromol/L exhibited no cytotoxicity against human periodontal membrane fibroblasts (P > 0.05). Bacterial morphological changes induced by MIC of cecropin-XJ examined on SEM showed cell surface disruption. Furthermore, the ability of A. naeslundii adhesion to S-HA decreased significantly with MIC of cecropin-XJ for 10 and 20 minutes (P = 0.001 and 0.000, respectively), and S. mutans, A. viscosus to S-HA decreased significantly with MIC of cecropin-XJ for 20 minutes (P = 0.000, respectively). CONCLUSIONS: Cecropin-XJ exhibited bactericidal action against cariogenic pathogens, and the antibacterial activity enhanced in the acid environment. The results also demonstrate that cecropin-XJ prevents S. mutans and actinomyces adsorption to S-HA. These findings suggest that Cecropin-XJ may have potential to prevent caries.

[Effect of para-aminobenzonic acid on cell-surface hydrophobicity of Actinomyces viscosus].

OBJECTIVE: To study the effect of Para-aminobenzonic acid (PABA) on cell-surface hydrophobicity of Actinomyces viscosus. METHODS: Microbial adhesion to hydrocarbons (MATH) was used to measure the cell-surface hydrophobicity of Actinomyces viscosus which grew in modified Carlsson medium with different dilution of PABA. RESULTS: Following the increase of concentration of PABA, the value of cell-surface hydrophobicity of Actinomyces viscosus decreased, which were 0.38900 +/- 0.00026, 0.25462 +/- 0.00168, 0.16360 +/- 0.00026 respectively(P < 0.05). CONCLUSION: PABA could inhibit the adherence of Actinomyces viscosus by way of changing its cell-surface hydrophobicity.

[Effect of Radix scutellariae on the growth and form of Porphyromanus endodontics in vitro].

OBJECTIVE: To provide scientific evidence for underpinning the use of Radix Scutellariae in the treatment of pulp and periapical diseases. METHODS: Using minute amount serial dilution test, this study assessed the minimal inhibitory concentration of Radix Scutellariae extreact against Porphyromanus Endodontics. The forms of Porphyromanus endodontics treated with Radix Scutellariae extract at different concentrations were observed by use of SEM. RESULTS: The MIC of Radix Scutellariae extract was determined to be 1 mg/ml. Radix Scutellariae changed the forms of Porphyromanus endodontics, making them become bigger, longer and crumbled. CONCLUSION: Radix Scutellariae could inhibit the growth of Porphyromanus Endodontics.

[Acquisition of Mutans streptococci by children of 3-4 years with possible source of the pathogen from their mothers].

OBJECTIVE: The aim of this study was to investigate the prevalence of Mutans streptococci (MS) in children of 3-4 years and thus reveal the relationship between the children's acquisition of MS and their mothers' pathogen. METHODS: Fifty mother-child pairs were selected, examined and divided into three groups according to the children's caries. MS in plaque and mothers' salivary samples were detected by MSB medium. Then 200 MS strains from 20 mothers-children were analyzed by AP-PCR. RESULTS: Acquisition of MS was identified in 37 of 50 children (74%), including 11 of 24 caries-free children and all 26 children with caries. The difference was significant (P<0.01). Genotypes showed that 16 of 37 children (43.2%) had the same fingerprint as their mothers'. The level of MS identified in mothers' salivary sample was lower than that in mothers' plaque sample (32% and 56%). CONCLUSION: These results suggested that caries in children of 3-4 years are closely related with MS acquisition. Mothers are still their important source of MS. The sensitivity of mothers' salivery samples is much lower than that of plaque samples in studying the transmission of MS.

[A comparative study utilizing different methods for establishing an experimental periodontitis model in rats].

OBJECTIVE: To evaluate the experimental periodontitis in rats induced by ligature plus high sugar water with and without infection of periodontopathic bacteria. METHODS: Forty SD rats (5 weeks of age) were randomly divided into a control group (N) and three experimental groups (P1, P2 and P3). All experimental groups were given silk ligatures around the cervix of the second maxillary molars and were provided with drinking water containing 10% glucose. Group P2 was inoculated with P. gingivalis, three times; group P3 was inoculated with P. gingivalis and F. nucleatum, three times. At weeks 0, 2 and 4, microbiological and histological examinations were made; alveolar bone loss was stereoscopically measured as the distance from the cement-enamel junction to the alveolar crest. RESULTS: Microbiological examination indicated that the bacteria inoculated in groups P2 and P3 were successfully colonized and both of P. gingivalis and F. nucleatum were predominant among the bacterial colonies of the examined sites. At week 2, histological examination showed gingival erosion and alveolar bone loss in all experimental groups and periodontal pockets in groups P2 and P3. The most serious lesions were observed in group P3. At week 4, the periodontal destruction in all experimental groups became more severe. CONCLUSION: Ligature, high sugar water combined with mixed infection of periodontopathic bacteria can successfully induce experimental periodontitis in rats.

[Purification and characterization of sanguicin--a bacteriocin produced by Streptococcus sanguis].

OBJECTIVE: Streptococcus sanguis plays an important Role in maintaining the periodontal microecological balance. Previous studies have demonstrated that sanguicin--a kind of bacteriocin produced by S. sanguis has a prominent function of inhibiting the growth of putative periodontopathic bacteria (PPB). The aim of this study was to purify sanguicin and investigate its characters. METHODS: The raw extract of sanguicin was obtained from cells of S. sanguis by ultrasonication, salting out and dialysis. Then the diethyl-aminoethyl-sepharose gradual washing was done in conjunction with glucosan gel filtration for in the purfication of sanguicin. The characters of purified sanguicin were determined and its inhibitiory effect on PPB was measured by agar diffusion test. RESULTS: The purifed sanguicin was obtained; it was heat labile and proteinaceous; and by SDS-PAGE, it showed a main band with the relative molecular mass of 65 x 10(3). The purifed sanguicin had a strong inhibitory effect on P. gingivalis, P. intermedia and F. nucleatum in vitro. CONCLUSION: Our methods are useful for the purification of sanguicin. Sanguicin has inhibitory effect on PPB obviously and will have a good prospect in periodontal ecological therapy.

Effects of salt stress on antioxidant defense system in the root of Kandelia candel.

BACKGROUND: This study aimed to explore the active oxygen scavenging mechanism of Kandelia candel, in order to provide a theoretical basis for further analysis on the physiological mechanism of salt tolerance in mangrove plants. Different concentrations of NaCl solution (0, 150, 300 and 450 mmol/L) were used for salt stress treatments on Kandelia candel, physiological indicators in the root of Kandelia candel were measured in different processing time. RESULTS: With the increase of salt concentrations and processing time, the contents of total proteins in the root of Kandelia candel were reduced; the CAT activity, SOD activity, ASA content and MDA content all had decreased with the increase of salt concentrations and shown a trend from ascent to descent with the increase of processing time, the peak of ASA and MDA contents were observed at 6 h, that of SOD activity was observed at 9 h and that of CAT activity was at 12 h; POD activity had shown an overall upward trend with the increase of salt concentrations and processing time, which reached the maximum at 24 h; the variations of these physiological indicators were more significant in high concentrations of NaCl solution (450 mmol/L). CONCLUSIONS: A certain salt concentration (<300 mmol/L) was required for the growth of Kandelia candel seedlings. At the early stage of high-salt stress, Kandelia candel can rapidly activate antioxidant defense system to resist the salt induced oxidative stress, thus reducing the damages of oxidative stress to plasma membrane, which might be an effective means for Kandelia candel to resist high salt stress.

[The novel species and genus discovered and nominated from the human oral cavity in 2009--2012].

Bacterium is dominant microflora population in human oral cavity, and the novel species and novel genus were discovered and named one after another. This article reviewed the major biological characteristics of 5 novel genus and 16 novel species isolated from the human oral cavity from 2009 to 2012.

[The antagonistic effect of the oral Streptococcus on the Saccharomyces albicans in vitro].

OBJECTIVE: To investigate the antagonistic effects of three species of oral Streptococcus on the growth of oral Saccharomyces albicans in vitro. METHODS: Direct inoculation method, reverse inoculation method and mixed culture methods were respectively chosen to observe the changes of Saccharomyces albicans colony formation on the effects of Streptococcus mutans, Streptococcus sanguis and Streptococcus salivarius. RESULTS: 1) No clear inhibition zone was observed in each of the groups by direct inoculation method. 2) Compared with the control groups, Saccharomyces albicans colony formation on soft agar of Streptococcus sanguis decreased significantly (P < 0.05). 3) Mixed culture method results showed that Streptococcus mutans could inhibit the growth of Saccharomyces albicans significantly at different time points (P = 0.001). 4) Under the action of bacteria culture supernatant, the count of Saccharomyces albicans in experiment groups showed statistical significance when compared with the control groups at 24, 48, 72 h (P = 0.001); The differences among the experimental groups were of no statistical significance at majority times (P > 0.05). CONCLUSION: Streptococcus mutans, Streptococcus sanguis, and Streptococcus salivarius could obviously inhibit the growth of Saccharomyces albicans in vitro. However, it is still unclear that among which the inhibition effects is stronger. The antagonistic effects is weakened gradually.

[The disinfection efficiency observation of a compound disinfectant spray on dental impression and plaster].

OBJECTIVE: The disinfection efficiency of a compound disinfectant spray with trichioro hydroxyl diphenyl ether on dental impression and plaster model, which have been contaminated by pathogens, were evaluated in this study. METHODS: As experimental group, germ-free alginate impressions and plaster models were sprayed with the compound disinfectant of different density trichloro hydroxyl diphenyl ether or indophors for 5, 10 and is mm, after which were smeared with five tested pathogens, including Staphylococcus acre us, Escherichia cali, Saccharomyces albicans, Streptococcus mutans and black spore variants of Bacillus subtilis. The colonies were counted after sampling, inoculate and culture, which were used to deduce the killing logarithm value as the standard of the disinfecting efficiency. RESULTS: the compound disinfectant spray with 3000 mg x L(-1) triebloro hydroxyl diphenyl ether was effective to all tested pathogens for 10 mm whatever on the impressions or the plaster models. The disinfectant spray with tame concentration was more effective on the alginate impression than on the plaster model in the same time (P = 0.000). CONCLUSION: The compound disinfectant spray with trichioro hydroxyl diphenyl ether is an effective antiseptics for alginate impressions and plaster models.