Correlation between different points on the face and the width of maxillary anterior teeth.

Statement of problem: There is currently no consensus on the relationship between maxillary anterior teeth and different facial anthropometric measurements. Additionally, whether these relationships vary by age and sex remains unreported. Purpose: This clinical study aimed to investigate the relationship between the intercanine distance (ICaD) and intercanthal distance (ICD), interpupillary distance (IPD), interalar width (IAW), and intercommissural width (ICW), and to compare whether these relationships differ between different age and sex populations. Material and methods: Participants (n = 409) were enrolled according to the inclusion criteria, and their standardized digital images were taken to measure facial and oral segments through an image processing program. The differences between ICaD and four facial measurements and the sexual differences for all measurements were compared using the 1-sample t-test. The differences among different age groups for all measurements were compared using the one-way analysis of variance (ANOVA) test, and a least significant difference (LSD) test was used for multiple comparisons. The association between ICaD and the four facial measurements was evaluated using Pearson correlation analysis. The correlation between ICaD and four facial measurements was evaluated using linear regression. Differences in regression equations among the subgroups were evaluated through subgroup regression analysis and the significance test of the difference between the two regression coefficients. Tests of significance were two-sided, with alpha level of 0.05. The reliability of the results was evaluated by calculating intraclass correlation coefficients. Results: The ICD, IPD, ICW, and IAW significantly differed from the ICaD in both sexes (P < 0.01). All measurements were significantly greater in men than in women (P < 0.01). The differences among the age groups were statistically significant for all measurements except IPD (P < 0.05). A significant positive correlation was found between all facial measurements (r = 0.258 [ICD], r = 0.334 [IPD], r = 0.389 [ICW], and r = 0.393 [IAW]) and the ICaD in both sexes. The highest correlation was found between ICW(r = 0.345) and ICAD in men and IAW (r = 0.285) and ICAD in women. Except for the 20-29 and 50-59 age groups, the mathematical equations of ICaD and facial anthropometric measurements differed among the other age groups and sexes. Conclusions: ICD, IPD, ICW, and IAW cannot be directly used to determine ICaD in both sexes. Nevertheless, when observed from the frontal aspect, by the use of digital images, all facial measurements correlated to the intercanine distance, with a high probability. The mathematical formulae combined with facial anthropological measurements can help ensure the combined width of the six maxillary anterior teeth, but the effects of sex and age differences should be considered.

Iva xanthiifolia leaf extract reduced the diversity of indigenous plant rhizosphere bacteria.

BACKGROUND: Iva xanthiifolia, native to North America, is now widely distributed in northeastern China and has become a vicious invasive plant. This article aims to probe the role of leaf extract in the invasion of I. xanthiifolia. METHODS: We collected the rhizosphere soil of Amaranthus tricolor and Setaria viridis in the invasive zone, the noninvasive zone and the noninvasive zone treated with extract from I. xanthiifolia leaf, and obtained I. xanthiifolia rhizosphere soil in the invasive zone. All wild plants were identified by Xu Yongqing. I. xanthiifolia (collection number: RQSB04100), A. tricolor (collection number: 831,030) and S. viridis (collection number: CF-0002-034) are all included in Chinese Virtual Herbarium ( https://www.cvh.ac.cn/index.php ). The soil bacterial diversity was analyzed based on the Illumina HiSeq sequencing platform. Subsequently, taxonomic analysis and Faprotax functional prediction were performed. RESULTS: The results showed that the leaf extract significantly reduced the diversity of indigenous plant rhizosphere bacteria. A. tricolor and S. viridis rhizobacterial phylum and genus abundances were significantly reduced under the influence of I. xanthiifolia or its leaf extract. The results of functional prediction showed that bacterial abundance changes induced by leaf extracts could potentially hinder nutrient cycling in native plants and increased bacterial abundance in the A. tricolor rhizosphere related to aromatic compound degradation. In addition, the greatest number of sensitive Operational Taxonomic Units (OTUs) appeared in the rhizosphere when S. viridis was in response to the invasion of I. xanthiifolia. It can be seen that A. tricolor and S. viridis have different mechanisms in response to the invasion of I. xanthiifolia. CONCLUSION: I. xanthiifolia leaves material has potential role in invasion by altering indigenous plant rhizosphere bacteria.

Comparison of maxillary anterior mathematical proportions among 3 dental arch forms.

STATEMENT OF PROBLEM: Race and sex differences in the mathematical proportions of maxillary anterior teeth have been evaluated. However, studies exploring the relationship between the mathematical proportion of maxillary anterior teeth and maxillary dental arch form are lacking. PURPOSE: The purpose of this clinical study was to determine if a correlation exists between the mathematical proportions of maxillary anterior teeth and 3 dental arch forms. MATERIAL AND METHODS: Three hundred young participants were recruited according to predefined criteria, and images and maxillary casts were obtained. The perceived width and length of the maxillary anterior teeth were measured on the images by using a software program, and mathematical proportions, including width ratios and width-to-length ratios, were calculated for each. The casts were used to categorize each specimen into tapered, ovoid, or square groups by using a specific classification method, and the width ratios and width-to-height ratios of the 3 dental arch forms were compared. Statistical analysis was performed by using analysis of variance (ANOVA) or the Kruskal-Wallis H test to compare the mathematical proportions of maxillary anterior teeth among the 3 dental arch forms (α=.05). The intraclass correlation coefficient (ICC) was used to test the reliability of the investigators. RESULTS: Except for the width-to-length ratios of the central incisor, mathematical proportions were affected by the dental arch form. The perceived width ratios of the maxillary lateral incisor-to-central incisor gradually increased from the tapered arch to the ovoid arch and from the ovoid arch to the square arch, with mean ±standard deviation values of 0.71 ±0.04, 0.73 ±0.05, and 0.79 ±0.06, respectively. For the maxillary perceived width ratios of canine-to-lateral incisor, the ovoid arch had the maximum perceived width ratios (0.86 ±0.10), followed by the tapered (0.82 ±0.10) and square arches (0.77 ±0.11). The width-to-length ratios of the central incisor were not affected by the arch form (P=.075), and the width-to-length ratios of the lateral incisor increased as the arch form became flat, with respective values of 0.70 ±0.10, 0.74 ±0.10, and 0.76 ±0.10. For the width-to-length ratios of the canine, the ovoid arch had the maximum perceived width ratios (0.58 ±0.10), followed by the tapered (0.53 ±0.10) and square arches (0.52 ±0.10). CONCLUSIONS: The mathematical proportions varied among the 3 dental arch forms, and the dental arch form should be considered during the prosthodontic design of maxillary anterior teeth.

Relationship between phytoplankton community and water parameters in planted fringing mangrove area in South China.

Reforestation has been commonly adopted to increase the mangrove areas lost due to developments. A diverse phytoplankton community is critical to mangrove ecosystem functions; however, its compositions in planted mangrove habitats have seldom been reported. The present study, based on the temporal and spatial variations of phytoplankton community and water parameters, evaluated their relationships in a 20-year old artificially planted fringing mangrove in South China. Thirty-one phytoplankton taxa were identified from tidal water collected from three sites along a planted mangrove shoreline: within, and at the edge of mangroves, and at bare shoreline without mangroves. In all three sites, Bacillariophyta (diatom) was the most abundant phylum, dominated by Navicula and Nitzschia at 9.82-83.76% and 2.57-33.97%, respectively. The overall diversity ranged between 0.41 and 1.94. The temporal variations of phytoplankton and water parameters were more obvious than site differences. Higher phytoplankton diversity was found in summer, with increased green algae and cyanobacteria abundance accompanied by riverine discharge. There was site-specific dominance in some phyla between June and January, noticeably Chlorophyta, Cyanophyta, Dinophyta, and Euglenophyta. A potential toxic dinoflagellate Peridinium sp. was identified during fall and winter, serving as a warning to probable harmful bloom events. Multivariate statistical analyses revealed the abundance of major phytoplankton taxa significantly related to water physiochemical parameters, especially nitrate, ammonium, total phosphorous and orthophosphate. The present study suggests that mangrove vegetation may influence water quality and shape phytoplankton composition, but temporal differences were more significant. Compared with the protected natural mangroves in the National Nature Reserve nearby, this planted fringing mangrove habitat not only had lower nutrients, especially total nitrogen in tidal water, but also had different dominant phytoplankton species and lower species richness. The 20-year old artificially planted mangroves may still not serve the same ecological function as the protected natural mangrove forest.

Genome-wide identification of wheat (Triticum aestivum) expansins and expansin expression analysis in cold-tolerant and cold-sensitive wheat cultivars.

Plant expansins are proteins involved in cell wall loosening, plant growth, and development, as well as in response to plant diseases and other stresses. In this study, we identified 128 expansin coding sequences from the wheat (Triticum aestivum) genome. These sequences belong to 45 homoeologous copies of TaEXPs, including 26 TaEXPAs, 15 TaEXPBs and four TaEXLAs. No TaEXLB was identified. Gene expression and sub-expression profiles revealed that most of the TaEXPs were expressed either only in root tissues or in multiple organs. Real-time qPCR analysis showed that many TaEXPs were differentially expressed in four different tissues of the two wheat cultivars-the cold-sensitive 'Chinese Spring (CS)' and the cold-tolerant 'Dongnongdongmai 1 (D1)' cultivars. Our results suggest that the differential expression of TaEXPs could be related to low-temperature tolerance or sensitivity of different wheat cultivars. Our study expands our knowledge on wheat expansins and sheds new light on the functions of expansins in plant development and stress response.

Does energetic cost for leaf construction in Sonneratia change after introduce to another mangrove wetland and differ from native mangrove plants in South China?

Exotic species invasions are serious ecological problems. Leaf construction cost (CC) and growth traits of two Sonneratia (Sonneratia caseolaris and S. apetala) and four native species (Bruguiera gymnorrhiza, Kandelia obovata, Aegiceras corniculatum and Avicennia marina) in Hainan and Shenzhen mangrove wetlands were compared to evaluate invasive potentials of Sonneratia after introduced to Shenzhen, their new habitat. There were no significant differences in CC and growth traits between two wetlands, suggesting Sonneratia did not lose any advantage in the new habitat and were competitive in both wetlands. CC per unit mass (CCM), CC per unit area (CCA) and caloric values of Sonneratia were significantly lower than those of native mangrove species while specific leaf area (SLA) was just the opposite. CCM of S. caseolaris and S. apetala were 6.1% and 11.9% lower than those of natives, respectively. These findings indicated the invasive potential of Sonneratia in Shenzhen after their introduction.

Role of tRNA selenocysteine 1 associated protein 1 in the proliferation and apoptosis of cardiomyocyte­like H9c2 cells.

Transfer RNA selenocysteine 1 associated protein 1 (Trnau1ap) serves an essential role in the synthesis of selenoproteins, which have critical functions in numerous biological processes. Selenium deficiency results in a variety of diseases, including cardiac disease. However, the mechanisms underlying myocardial injury induced by selenium deficiency remain unclear. The present study examined the effects of Trnau1ap under­ and overexpression in cardiomyocyte­like H9c2 cells, by transfection with small interfering RNA and an overexpression plasmid, respectively. Expression levels of glutathione peroxidase, thioredoxin reductase and selenoprotein K were decreased in Trnau1ap­underexpressing cells, and increased in Trnau1ap­overexpressing cells. Using MTT, proliferating cell nuclear antigen, annexin V and caspase­3 activity assays, it was demonstrated that reducing Trnau1ap expression levels inhibited the proliferation of H9c2 cells and induced apoptosis. Conversely, increasing Trnau1ap expression levels promoted cell growth. Western blot analysis revealed that the phosphoinositide 3­kinase/protein kinase B signaling pathway was activated in Trnau1ap­underexpressing cells. Furthermore, the apoptotic pathway was activated in these cells, evidenced by relatively greater expression levels of B­cell lymphoma (Bcl­2)­associated X protein and reduced expression levels of Bcl­2. Taken together, these findings suggest that Trnau1ap serves a key role in the proliferation and apoptosis of H9c2 cells. The present study provides insight into the underlying mechanisms of myocardial injury induced by selenium deficiency.

Are Photosynthetic Characteristics and Energetic Cost Important Invasive Traits for Alien Sonneratia Species in South China?

A higher photosynthesis and lower energetic cost are recognized as important characteristics for invasive species, but whether these traits are also important for the ability of alien mangrove species to become invasive has seldom been reported. A microcosm study was conducted to compare the photosynthetic characteristics, energetic cost indices and other growth traits between two alien species (Sonneratia apetala and S. caseolaris) and four native mangrove species over four seasons in a subtropical mangrove nature reserve in Shenzhen, South China. The aim of the study was to evaluate the invasive potential of Sonneratia based on these physiological responses. The annual average net photosynthetic rate (Pn), stomatal conductance (Gs) and total carbon assimilation per unit leaf area (Atotal) of the two alien Sonneratia species were significantly higher than the values of the native mangroves. In contrast, the opposite results were obtained for the leaf construction cost (CC) per unit dry mass (CCM) and CC per unit area (CCA) values. The higher Atotal and lower CC values resulted in a 72% higher photosynthetic energy-use efficiency (PEUE) for Sonneratia compared to native mangroves, leading to a higher relative growth rate (RGR) of the biomass and height of Sonneratia with the respective values being 51% and 119% higher than those of the native species. Higher photosynthetic indices for Sonneratia compared to native species were found in all seasons except winter, whereas lower CC values were found in all four seasons. The present findings reveal that alien Sonneratia species may adapt well and become invasive in subtropical mangrove wetlands in Shenzhen due to their higher photosynthetic characteristics coupled with lower costs in energy use, leading to a higher PEUE. The comparison of these physiological responses between S. apetala and S. caseolaris reveal that the former species is more invasive than the latter one, thus requiring more attention in future.

Sex- and season-dependent differences in telomere length and telomerase activity in the leaves of ash and willow.

Telomeres and telomerase have important biological functions and can protect chromosome ends. In this study, sex- and season-dependent changes in telomere length and telomerase activity in ash and willow were analyzed. A statistical analysis showed that the telomere lengths of male and female trees differed significantly (P < 0.05). In ash, the telomere lengths of female trees were shorter than those of male trees. In willow, the telomere lengths of female trees were longer than those of male trees. During the annual developmental cycle, the telomere lengths of male and female ash and willow increased from April to May (P < 0.05), remained stable from May to August (P > 0.05), and decreased significantly in September and October (P < 0.05). Additionally, telomerase activities could be detected in both male and female ash and willow trees from April to October. Our results show that the telomere lengths changed according to season and sex in ash and willow. Telomere length did not have a direct positive correlation with telomerase activity.

Dishevelled-1 (Dvl-1) protein: a potential participant of oxidative stress induced by selenium deficiency.

Oxidative stress induced by selenium deficiency has been shown to be associated with cardiovascular diseases. Nevertheless, the mechanism associated with oxidative stress induced by selenium deficiency is poorly understood. In the present study, 36 weaning C57BL/6 mice were randomly divided into 4 groups as follows: control (n =9), 4-week selenium deficiency (n =9), 8-week selenium deficiency (n = 9), and 12-week selenium deficiency (n =9). The levels of myocardial glutathione peroxidase (GPx), superoxide dismutase (SOD), and malondialdehyde (MDA) were determined by Western blotting or commercial kits. Real-time PCR was performed to detect the mRNA expression of dishevelled-1 (Dvl-1) protein. Western blotting was conducted to evaluate the protein expression levels of Dvl-1 and ß-catenin. Our results demonstrated that the levels of GPx and SOD were significantly reduced, along with an increase in MDA in selenium-deficient mice. Importantly, Dvl-1 and ß-catenin were clearly upregulated under oxidative stress. Collectively, our findings indicate that Dvl-1 may be an underlying participant of oxidative stress induced by selenium deficiency.

Mmu-miR-702 functions as an anti-apoptotic mirtron by mediating ATF6 inhibition in mice.

MicroRNAs (miRNAs) are a group of endogenous, small, noncoding RNAs that function as key post-transcriptional regulators. miRNAs are involved in many biological processes including apoptosis. In this study, mouse miR-702 (mmu-miR-702), a mirtron derived from the 13th intron of the Plod3 gene, was identified as a regulator of anti-apoptosis. mmu-miR-702 was down-regulated after treatment with the apoptosis-inducer isoproterenol both in vivo and in vitro. According to over-expression experiments, mmu-miR-702 inhibited apoptosis as well as the expression levels of a subset of apoptosis-related genes including activating transcription factor 6 (ATF6). An interaction between mmu-miR-702 and the ATF6 3'-UTR binding site was confirmed using luciferase reporter and western blot assays. This is the first report of ATF6 interaction with miRNA. Although the possible existence of miR-702 in the human genome is low, our results indicate that mirtrons also participate in the process of apoptosis and may provide a novel study strategy for apoptosis.

Two novel diacylglycerol acyltransferase genes from Xanthoceras sorbifolia are responsible for its seed oil content.

Xanthoceras sorbifolia is an excellent model system for studying triacylglycerol (TAG) biosynthesis in woody oilseed plants due to the high amount of seed oil, which is important for food and industrial uses. TAG is the major form of stored lipids in seeds and diacylglycerol acyltransferase (DGAT; EC 2. 3. 1. 20) catalyzes the final and critical step of TAG synthesis. Here, two novel DGAT genes, designated XsDGAT1 and XsDGAT2, were cloned from developing X. sorbifolia embryos. Sequence analysis showed that XsDGAT1 had little sequence homology to XsDGAT2. Heterologous expression of XsDGAT1 and XsDGAT2 in TAG-deficient yeast mutants restored TAG synthesis, confirming their biological activity. Expression of the two genes in wild-type Arabidopsis led to TAG synthesis and an increase in total seed oil in transgenic plants, with XsDGAT1 appearing to contribute to TAG synthesis at a greater level. Comparison of the expression patterns revealed that both XsDGAT1 and XsDGAT2 were expressed in the examined tissues and had similar spatiotemporal expression patterns with higher expression in embryos than in leaves and petals. The expression patterns of both XsDGAT1 and XsDGAT2 correlated with oil accumulation in developing X. sorbifolia embryos. These data suggest that XsDGAT1 and XsDGAT2 are both responsible for TAG synthesis in X. sorbifolia seeds.

Recombinant Escherichia coli Trx-JZTX-III represses the proliferation of mouse hepatocellular carcinoma cells through induction of cell cycle arrest.

The aim of the present study was to investigate the effects of recombinant Escherichia coli (E. coli) Trx-jingzhaotoxin (JZTX)-III on cell growth in the mouse hepatocellular carcinoma (HCC) cell line Hepa1-6. The JZTX-III gene sequence was synthesized and cloned into the pET-32a(+) vector to construct the recombinant fusion protein Trx-JZTX-III, which was subsequently purified. Hepa1-6 cells were treated with 0 to 1,000-µg/ml concentrations of Trx-JZTX-III; this was demonstrated to affect cell viability, as determined by the 3-(4,5-dimethylthiazol­2-yl)-2,5-diphenyltetra-zolium bromide (MTT) assay. The expression of the proliferating cell nuclear antigen (PCNA) protein was investigated using western blot analysis. A colony formation assay was used to determine Hepa1-6 cell proliferation, and the migration ability of cells was determined using a wound­healing assay. Additionally, flow cytometry was employed to observe changes in the cell cycle. The MTT assay and quantification of PCNA expression indicated that recombinant E. coli Trx-JZTX-III significantly repressed the proliferation of Hepa1-6 cells. Colony formation and the migration of malignant cells was inhibited following treatment with recombinant E. coli Trx-JZTX-III. Flow cytometry showed that recombinant E. coli Trx-JZTX-III induced G0/G1 cell cycle arrest. In conclusion, recombinant E. coli Trx-JZTX-III functions as a tumor suppressor drug in mouse HCC and its underlying mechanism may involve the induction of G0/G1 cell cycle arrest.

MicroRNA-30b-5p is involved in the regulation of cardiac hypertrophy by targeting CaMKIIδ.

BACKGROUND: MicroRNAs (miRNAs) participate in the regulation of cardiac hypertrophy. However, it remains largely unknown as to how miRNAs are integrated into the hypertrophic program. Ca/calmodulin-dependent protein kinase II (CaMKII) is a hypertrophic signaling marker. It is not yet clear which miRNAs can regulate CaMKIIδ. PURPOSE: In this study, we identified which miRNAs could regulate CaMKIIδ and how to regulate CaMKIIδ. METHODS: Through computational and expression analyses, miR-30b-5p was identified as a candidate regulator of CaMKIIδ. Quantitative expression analysis of hypertrophic models demonstrated significant down-regulation of miR-30b-5p compared with control groups. Luciferase reporter assay showed that miR-30b-5p could significantly inhibit the expression of CaMKIIδ. Moreover, through gain-of-function and loss-of-function approaches, we found miR-30b-5p could negatively regulate the expression of CaMKIIδ and miR-30b-5p was a regulator of cardiac hypertrophy. CONCLUSION: Our study demonstrates that the expression of miR-30b-5p is down-regulated in cardiac hypertrophy, and restoration of its function inhibits the expression of CaMKIIδ, suggesting that miR-30b-5p may act as a hypertrophic suppressor.

Tetrodotoxin attenuates isoproterenol-induced hypertrophy in H9c2 rat cardiac myocytes.

Cardiac hypertrophy is often associated with an increased sympathetic drive, and both in vitro and in vivo studies have demonstrated the development of cardiomyocyte hypertrophy in response to either α- or ß- adrenergic stimulation. The present study was carried out to determine whether the reversible sodium channel blocker tetrodotoxin (TTX) exerts a direct anti-hypertrophic effect on isoproterenol (ISO)-induced cell hypertrophy and find the underlying mechanism that regulate [Na(+)]( i ). The experiments were performed on cultured H9c2 cells exposed to ISO (10 µM) alone or combined with TTX (1 µM) for 48 h. Our results showed that ISO significantly increased cell surface area by 30 % and atrial natriuretic peptide gene expression by nearly twofold (p < 0.05 for both). These effects were associated with a significant reduction in the gene expression of Na(+)/K(+)-ATPase isoforms α2 and α3, whereas the α1 isoform was unaffected. Conversely, ISO increased Na(+)-H(+) exchanger 1 (NHE-1) gene expression by approximately 40 % and significantly increased [Na(+)]( i ) level by 50 % (p < 0.05 for both). ISO was also found to significantly increase aquaporin 4 gene expression by nearly ninefold (p < 0.05). All these effects were prevented when identical experiments were carried out in the presence of TTX, but the expression of NHE-1. The expression of sodium channel protein type 5 subunit alpha was unaffected by either ISO or TTX. When taken together, these studies show that TTX attenuates the hypertrophic effect of ISO and suggest a possible approach to limiting ISO-induced hypertrophy in clinical treatment.

NtCP56, a new cysteine protease in Nicotiana tabacum L., involved in pollen grain development.

Proteinases play a critical role in developmental homeostasis and in response to environ-mental stimuli. Our present research reports that a new cysteine protease, NtCP56, is involved in the development of pollen grains in Nicotiana tabacum L. The NtCP56 gene, which encodes a protein of 361 amino acid residues with a calculated molecular mass of 40 kDa, is strongly expressed in anthers. The recombinant NtCP56 showed a high activity towards casein. Kinetic analysis revealed a K(m) of 2.20 mg ml(-1) and V(max) of 11.07 microg ml(-1) min(-1). The recombinant NtCP56 retained more than 50% of its maximum enzymatic activity from 20 degrees C to 60 degrees C with an optimum Tm range of 30-50 degrees C. The enzyme had a maximum activity at approximately pH 6.5. Suppression of the NtCP56 gene in anti-sense transgenic tobaccos resulted in the sterility of pollen grains. Our data indicated that, as a cysteine protease, NtCP56 might play an important role in pollen development.

[Effect of surface treatment on the bonding of silicone elastomer to acrylic resin].

OBJECTIVE: To evaluate the effects of surface treatments on the bonding of silicone elastomer to acrylic resin. METHODS: Ninety acrylic resin specimens were randomly divided into 9 groups which were assigned to 9 different surface treatments: finished by 80-, 240-, 400-, 600-, 800-, 1000-, 1500-grit silicon carbide paper under running water, or polished or sandblasted. Roughness of the specimen surface was tested in each group, and the microstructure was observed with scanning electron microscopy (SEM). ZY-1 silicone elastomer, ZA-1 primer and acrylic resin specimens were prepared. Shear bond strength were tested and failure modes were assessed for all specimens. RESULTS: The roughness of all 9 groups showed significant difference (P < 0.05). The sandblasted group showed the highest roughness [(2.97 + or - 0.48) microm], the 1500-grit silicon carbide paper finished group showed the lowest roughness [(0.21 + or - 0.14) microm]. The sandblasted groups showed the lowest bonding strength [(0.98 + or - 0.11) MPa] (P < 0.05) while the 600-grit silicon carbide paper finished group showed the highest strength [(2.13 + or - 0.14) MPa]. CONCLUSIONS: Over high surface roughness does not improve the shear bond strength between silicone elastomer and acrylic resin. Treatment of acrylic resin surface with 600-grit silicon carbide paper can increase the shear bond strength between silicone elastomer and acrylic resin.

Isolation and differentiation of embryonic stem cells from BALB/c mouse / 神经科学通报·英文版

Objective To investigate the efficient method which can culture and induce embryonic stem cells to neurocyte in vitro. Methods Isolate the blastula of 3.5 d from BALB/c species mouse. Culture the cells from inner cell mass (ICM) which were isolated by mechanical method on the mouse embryonic fibroblaste cell (MEF) feeder layer or 0.1% gelatin coated dishes. The stem cells were identified by characterized morphology, alkaline phosphatase stain, differential potency in vivo and immunochemistry stain. The isolated cells were differentiated by serial induction method that mimicking the intrinsic developmental process of the neural system. Results The isolated cells were positive for alkaline phosphatatse and SSEA-1 (stage specific embryonic antigen 1). Moreover they were identified pluripotent by differentiation in vivo. Therefore the isolated cells presented the characters of ESCs. Then the isolated cells were able to differentiate into neurocytes in vitro. Conclusion Mouse embryonic stem cells isolation, culture and differentiation system has been established.

[Effects of cold-hardening on freezing tolerance and antioxidant enzyme activities in plantlets of Saussurea laniceps Hand.-Mazz].

Living conditions for plants in the mountains become increasingly less favorable with increasing altitude. In the alpine region, the plants are commonly exposed to daily rather than seasonal temperature fluctuations and by frequent freezing temperature. To elucidate the freezing tolerance mechanism of alpine plants, Saussurea laniceps Hand.-Mazz. was used as a model plant. It is a perennial herbal plant distributed in alpine regions of Yunnan and Tibet of China. It can survive on mountains with elevations over 4000 m. Wild S. laniceps plants are propagated only by seeds in the alpine areas. Micropropagation of S. laniceps through seed was a desirable method to get enough seedlings for freezing research. Micropropagation through plantlets derived from germinated S. laniceps seeds collected from Tibet was achieved successfully. Activities of antioxidant enzyme and solute contents were investigated in plantlets of S. laniceps. Freezing tolerance in plantlets increased after 7 or 15 d of cold-hardening (Table 1). Cold-hardening (2 degrees C) increased the activities of SOD, peroxidase, and catalase (Fig.1) in plantlets. A similar increase was also observed in the protein and proline content (Fig.1), whereas soluble carbohydrates changed little (Fig.1). These results obtained suggest that the higher activities of SOD, peroxidase, and catalase, as well as the higher protein and proline content may be biochemical adaptation for freezing toleranc in cold-hardened S. laniceps plantlets. Interestingly, deacclimation was slow; even after the plants were placed again under a temperature of 21-23 degrees C for 5 d, the higher freezing hardiness, enzyme activities, protein and proline content acquired after cold acclimation remained. In conclusion, our plantlet cultures have proved to be good materials for experimentation on freezing resistance in study of freezing-resistance mechanism in the alpine plant S. laniceps.