[Factors affecting stability after fixed orthodontic treatment]

Objective: To analyze factors affecting stability after fixed orthodontic treatment. Methods: Five hundred and forty-four patients who had finished fixed orthodontic treatment more than two years in First Department of Orthodontics, China Medical University from January, 2000 to December, 2017 were investigated and the rate of regular revisit was counted. The data of 288 patients were successfully collected by calling or sending text messages and the rate of standard use of retainers as prescribed (patients wore retainers for 24 months or longer) was counted. According to the variation of peer assessment rating (PAR) index at the start of retention and the time the data collected, the patients were divided into relapse group (variation of PAR index >5) and non-relapse group (variation of PAR index ≤5). Difference significance analysis and multiple-factor logistic regression analysis were used. Sixty patients wearing retainers well were collected and the curative effects of Hawley retainer and vacuum formed retainer (VFR) were compared, which included overbite, overjet, maxillary irregularity index, mandibular irregularity index, width betwenn canine and width between first molar. Results: The rate of regular revisit was 41.0% (223/544). Two hundred and one of 288 patients (69.8%) who were visited successfully had regular revisit, and 60.4%(174/288) of the patients wore retainers well; 30.2% (87/288) of the patients who were visited successfully didn't have regular revisit, and 10.4% (30/288) of the patients wore retainers well. Difference significance analysis showed that there was highly significant difference between relapse group and non-relapse group in the type of retainer and duration of retention (P<0.01). One hundred and forty of 224 patients (62.5%) in non-relapse group and 37.5% (24/64) of the patients in relapse group used VFR, and the duration of retention in non-relapse group was significantly longer than that in relapse group (P<0.01). Multiple-factor Logistic regression analysis showed that wearing Hawley retainers (OR=3.067, P<0.05) was the risk factor influencing relapse. The duration of retention (OR=0.832, P<0.01) was the protective factor influencing relapse. Independent-sample t test indicated that the variations of maxillary [(0.82±0.36) mm] and mandibular [(1.05±0.22) mm] irregularity index in Hawley retainer group were larger than maxillary [(0.64±0.29) mm] and mandibular [(0.72±0.35) mm)] irregularity index in VFR group, respectively. The differences between the two groups were significant (P<0.05). Conclusions: Duration of retention was implicated in stability after orthodontic treatment. VFR had better effect in the aspects of irregularity index than Hawley retainer.

Involvement of Three CsRHM Genes from Camellia sinensis in UDP-Rhamnose Biosynthesis

UDP-Rhamnose synthase (RHM), the branch-point enzyme controlling the nucleotide sugar interconversion pathway, converts UDP-d-glucose into UDP-rhamnose. As a rhamnose residue donor, UDP-l-rhamnose is essential for the biosynthesis of pectic polysaccharides and secondary metabolites in plants. In this study, three CsRHM genes from tea plants ( Camellia sinensis) were cloned and characterized. Enzyme assays showed that three recombinant proteins displayed RHM activity and were involved in the biosynthesis of UDP-rhamnose in vitro. The transcript profiles, metabolite profiles, and mucilage location suggest that the three CsRHM genes likely contribute to UDP-rhamnose biosynthesis and may be involved in primary wall formation in C. sinensis. These analyses of CsRHM genes and metabolite profiles provide a comprehensive understanding of secondary metabolite biosynthesis and regulation in tea plants. Moreover, our results can be applied for the synthesis of the secondary metabolite rhamnoside in future studies.

Effects of vitro sucrose on quality components of tea plants (Camellia sinensis) based on transcriptomic and metabolic analysis

BACKGROUND

Tea plants [Camellia sinensis (L.) O. Kuntze] can produce one of the three most widely popular non-alcoholic beverages throughout the world. Polyphenols and volatiles are the main functional ingredients determining tea's quality and flavor; however, the biotic or abiotic factors affecting tea polyphenol biosynthesis are unclear. This paper focuses on the molecular mechanisms of sucrose on polyphenol biosynthesis and volatile composition variation in tea plants.

RESULTS

Metabolic analysis showed that the total content of anthocyanins, catechins, and proanthocyanidins(PAs) increased with sucrose, and they accumulated most significantly after 14 days of treatment. Transcriptomic analysis revealed 8384 and 5571 differentially expressed genes in 2-day and 14-day sucrose-treated tea plants compared with control-treated plants. Most of the structural genes and transcription factors (TFs) involved in polyphenol biosynthesis were significantly up-regulated after 2d. Among these transcripts, the predicted genes encoding glutathione S-transferase (GST), ATP-binding cassette transporters (ABC transporters), and multidrug and toxic compound extrusion transporters (MATE transporters) appeared up regulated. Correspondingly, ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-QQQ-MS/MS) analysis revealed that the content of non-galloylated catechins and oligomeric PAs decreased in the upper-stem and increased in the lower-stem significantly, especially catechin (C), epicatechin (EC), and their oligomeric PAs. This result suggests that the related flavonoids were transported downward in the stem by transporters. GC/MS data implied that four types of volatile compounds, namely terpene derivatives, aromatic derivatives, lipid derivatives, and others, were accumulated differently after in vitro sucrose treatment.

CONCLUSIONS

Our data demonstrated that sucrose regulates polyphenol biosynthesis in Camellia sinensis by altering the expression of transcription factor genes and pathway genes. Additionally, sucrose promotes the transport of polyphenols and changes the aroma composition in tea plant.

A WD40 Repeat Protein from Camellia sinensis Regulates Anthocyanin and Proanthocyanidin Accumulation through the Formation of MYB⁻bHLH⁻WD40 Ternary Complexes

Flavan-3-ols and oligomeric proanthocyanidins (PAs) are the main nutritional polyphenols in green tea (Camellia sinensis), which provide numerous benefits to human health. To date, the regulatory mechanism of flavan-3-ol biosynthesis in green tea remains open to study. Herein, we report the characterization of a C. sinensis tryptophan-aspartic acid repeat protein (CsWD40) that interacts with myeloblastosis (MYB) and basic helix-loop-helix (bHLH) transcription factors (TFs) to regulate the biosynthesis of flavan-3-ols. Full length CsWD40 cDNA was cloned from leaves and was deduced to encode 342 amino acids. An in vitro yeast two-hybrid assay demonstrated that CsWD40 interacted with two bHLH TFs (CsGL3 and CsTT8) and two MYB TFs (CsAN2 and CsMYB5e). The overexpression of CsWD40 in Arabidopsis thaliana transparent testa glabra 1 (ttg1) restored normal trichome and seed coat development. Ectopic expression of CsWD40 alone in tobacco resulted in a significant increase in the anthocyanins of transgenic petals. CsWD40 was then coexpressed with CsMYB5e in tobacco plants to increase levels of both anthocyanins and PAs. Furthermore, gene expression analysis revealed that CsWD40 expression in tea plants could be induced by several abiotic stresses. Taken together, these data provide solid evidence that CsWD40 partners with bHLH and MYB TFs to form ternary WBM complexes to regulate anthocyanin, PA biosynthesis, and trichome development.

Titanium dioxide nanoparticles induce in vitro autophagy

Aim:

Concerns about the possible toxicity to environment and human health of titanium dioxide nanoparticles (TiO2 NPs) are increasing. The aim of this study was to investigate the relationship between toxicology and autophage in vitro.

Methods:

RAW 264.7 cells were exposed to five concentrations (50, 100, 200, 300, and 400 μg/mL) and two particle size of TiO2 NPs (30 and 100 nm) for 24 h.

Results:

The results showed that TiO2 NPs decreased cell viability, phagocytic rate, and phagocytic index in a concentration-dependent manner, thereby inducing autophagy. TiO2 NPs-induced autophagy was indicated by monodansyl cadaverine staining and transmission electron microscopy. TiO2 NPs-induced messenger RNA expression of autophagy-related proteins LC3 and Beclin-1 was also significantly increased compared with those of the unexposed control cells. LC3 and Beclin-1 protein expression levels were markedly increased with the increase of TiO2 NPs concentrations.

Conclusion:

These results suggest the possibility that TiO2 NPs-induced toxicology probably plays a key role in autophagy in RAW 264.7 cells, and further exhaustive research on the harmful effects of these NPs in relevant organisms is needed for their safe application.

Insight into Catechins Metabolic Pathways of Camellia sinensis Based on Genome and Transcriptome Analysis

Tea is an important economic crop with a 3.02 Gb genome. It accumulates various bioactive compounds, especially catechins, which are closely associated with tea flavor and quality. Catechins are biosynthesized through the phenylpropanoid and flavonoid pathways, with 12 structural genes being involved in their synthesis. However, we found that in Camellia sinensis the understanding of the basic profile of catechins biosynthesis is still unclear. The gene structure, locus, transcript number, transcriptional variation, and function of multigene families have not yet been clarified. Our previous studies demonstrated that the accumulation of flavonoids in tea is species, tissue, and induction specific, which indicates that gene coexpression patterns may be involved in tea catechins and flavonoids biosynthesis. In this paper, we screened candidate genes of multigene families involved in the phenylpropanoid and flavonoid pathways based on an analysis of genome and transcriptome sequence data. The authenticity of candidate genes was verified by PCR cloning, and their function was validated by reverse genetic methods. In the present study, 36 genes from 12 gene families were identified and were accessed in the NCBI database. During this process, some intron retention events of the CsCHI and CsDFR genes were found. Furthermore, the transcriptome sequencing of various tea tissues and subcellular location assays revealed coexpression and colocalization patterns. The correlation analysis showed that CsCHIc, CsF3'H, and CsANRb expression levels are associated significantly with the concentration of soluble PA as well as the expression levels of CsPALc and CsPALf with the concentration of insoluble PA. This work provides insights into catechins metabolism in tea and provides a foundation for future studies.

Effect of replacing calcium salts of palm oil with camelina seed at 2 dietary ether extract levels on digestion, ruminal fermentation, and nutrient flow in a dual-flow continuous culture system

Camelina is a drought- and salt-tolerant oil seed, which in total ether extract (EE) contains up to 74% polyunsaturated fatty acids. The objective of this study was to assess the effects of replacing calcium salts of palm oil (Megalac, Church & Dwight Co. Inc., Princeton, NJ) with camelina seed (CS) on ruminal fermentation, digestion, and flows of fatty acids (FA) and AA in a dual-flow continuous culture system when supplemented at 5 or 8% dietary EE. Diets were randomly assigned to 8 fermentors in a 2 × 2 factorial arrangement of treatments in a replicated 4 × 4 Latin square design, with four 10-d experimental periods consisting of 7 d for diet adaptation and 3 d for sample collection. Treatments were (1) calcium salts of palm oil supplementation at 5% EE (MEG5); (2) calcium salts of palm oil supplementation at 8% EE (MEG8); (3) 7.7% CS supplementation at 5% EE (CS5); and (4) 17.7% CS supplementation at 8% EE (CS8). Diets contained 55% orchardgrass hay, and fermentors were fed 72 g of dry matter/d. On d 8, 9, and 10 of each period, digesta effluent samples were taken for ruminal NH₃, volatile fatty acids, nitrogen metabolism analysis, and long-chain FA and AA flows. Statistical analysis was performed using the MIXED procedure (SAS Institute Inc., Cary, NC). We detected an interaction between FA source and dietary EE level for acetate, where MEG8 had the greatest molar proportion of acetate. Molar proportions of propionate were greater and total volatile fatty acids were lower on CS diets. Supplementation of CS decreased overall ruminal nutrient true digestibility, but dietary EE level did not affect it. Diets containing CS had greater biohydrogenation of 18:2 and 18:3; however, biohydrogenation of 18:1 was greater in MEG diets. Additionally, CS diets had greater ruminal concentrations of trans-10/11 18:1 and cis-9,trans-11 conjugated linoleic acid. Dietary EE level at 8% negatively affected flows of NH₃-N (g/d), nonammonia N, and bacterial N as well as the overall AA outflow. However, treatments had minor effects on individual ruminal AA digestibility. The shift from acetate to propionate observed on diets containing CS may be advantageous from an energetic standpoint. Moreover, CS diets had greater ruminal outflow of trans-10/11 18:1 and cis-9,trans-11 conjugated linoleic acid than MEG diets, suggesting a better FA profile available for postruminal absorption. However, dietary EE at 8% was deleterious to overall N metabolism and AA outflow, indicating that CS can be fed at 5% EE without compromising N metabolism.

Diffusion kurtosis imaging in identifying the malignancy of lymph nodes during the primary staging of rectal cancer

AIM

The aim was to assess the diagnostic value of diffusion kurtosis imaging (DKI) for discriminating between benign and malignant lymph nodes in patients with rectal carcinoma.

METHOD

ighty-five patients with rectal adenocarcinoma who underwent total mesorectal excision of the rectum were studied. A total of 273 lymph nodes were harvested and subjected to histological analysis. Quantitative parameters [apparent diffusion parameter D_app of the Gaussian distribution, apparent kurtosis coefficient K_app and apparent diffusion coefficient (ADC)] of lymph nodes were derived from DKI. Differences and the diagnostic performance of these parameters were calculated by using the independent-samples t test and receiver operating characteristic curve analyses.

RESULTS

The median D_app and ADC values of metastatic lymph nodes were significantly greater than those of benign lymph nodes, whereas the median K_app of metastatic lymph nodes was statistically less than that of normal lymph nodes. D_app had the relatively highest area under the curve of 0.774. When 1126.15 × 10^-6  mm² /s was used as a D_app threshold value, the sensitivity and specificity were 96.97% and 41.82%, respectively.

CONCLUSION

DKI can help differentiate metastatic vs benign lymph nodes during the primary staging of rectal cancer.

Evolutionary and functional characterization of leucoanthocyanidin reductases from Camellia sinensis

MAIN CONCLUSION

LARs promoted the biosynthesis of catechin monomers and inhibited their polymerization. The accumulation of catechin monomers and polymers was increased by up-regulating the expression of NtLAR and NtANR s in CsMYB5b transgenic tobacco. Tea is rich in polyphenolic compounds, and catechins are the major polyphenols in tea. The biosynthesis of polyphenols is closely related to the expression of the leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) genes. In this paper, an evolutionary analysis and functional characterization of three CsLARs were performed. The phylogenetic tree showed that plant LARs could be grouped into three, including gymnosperms, monocotyledons and dicotyledons (clusters I and II). The eighth amino acid residue in a conserved LAR-specific motif is changeable due to a transversion (G → T) and transition (G → C) that occur in the corresponding codon. Therefore, plant LARs can be classified as G-type, A-type and S-type LARs due to this variable amino acid residue. Although (2R, 3S)-trans-flavan-3-ols were the products of recombinant CsLARs proteins expressed in Escherichia coli, both (2R, 3S)-trans and (2R, 3R)-cis-flavan-3-ols were detected in tobacco overexpressing CsLARs. However, a butanol/HCl hydrolysis assay indicated that overexpression of the CsLARs caused a decrease in polymerized catechins. A hybridization experiment with CsLARc + AtPAP1 also showed that no polymers other than epicatechin, catechin and glycoside were detected, although the accumulation of anthocyanins was markedly decreased. CsMYB5b promoted the biosynthesis of both flavan-3-ols and proanthocyanidins (PAs). Therefore, LARs promoted the biosynthesis of catechin monomers and inhibited their polymerization. The accumulation of catechin monomers and polymers was increased by up-regulating the expression of the NtLAR and NtANRs in CsMYB5b transgenic tobacco.

Effects of Milk Proteins Supplementation in Older Adults Undergoing Resistance Training: A Meta-Analysis of Randomized Control Trials

BACKGROUND

Older adults experience age-related physiological changes that affect body weight and body composition. In general, nutrition and exercise have been identified as potent stimulators of protein synthesis in skeletal muscle. Milk proteins are excellent sources of all the essential amino acids and may represent an ideal protein source to promote muscle anabolism in older adults undergoing resistance training. However, several randomized control trials (RCTs) have yielded mixed results on the effects of milk proteins supplementation in combination with resistance training on body weight and composition.

METHODS

PubMed, Web of Science and Cochrane databases were searched for literature that evaluated the effects of milk proteins supplementation on body weight and composition among older adults (age ≥ 60 years) undergoing resistance training up to September 2016. A random-effects model was used to calculate the pooled estimates and 95% confidence intervals (CIs) of effect sizes.

RESULTS

The final analysis included 10 RCTs involving 574 participants (mean age range from 60 to 80.8 years). Overall, the combination of milk proteins supplementation and resistance training did not have significant effect on fat mass (0.30, 95% CI -0.25, 0.86 kg) or body weight (1.02, 95% CI: -0.01, 2.04 kg). However, a positive effect of milk proteins supplementation paired with resistance training on fat-free mass was observed (0.74, 95% CI 0.30, 1.17 kg). Greater fat-free mass gains were observed in studies that included more than 55 participants (0.73, 95% CI 0.30, 1.16 kg), and in studies that enrolled participants with aging-related medical conditions (1.60, 95% CI 0.92, 2.28 kg). There was no statistical evidence of publication bias among the studies.

CONCLUSION

Our findings provide evidence that supplementation of milk protein, in combination with resistance training, is effective to elicit fat-free mass gain in older adults.

Functional Analysis of an Uridine Diphosphate Glycosyltransferase Involved in the Biosynthesis of Polyphenolic Glucoside in Tea Plants (Camellia sinensis)

Polyphenols are one of the largest groups of compounds that confer benefits to the health of plants and humans. Flavonol glycosides are a major ingredient of polyphenols in Camellia sinensis. Flavonol-3-O-glycosides are characteristic astringent taste compounds in tea infusion. A polyphenolic glycosyltransferase (CsUGT72AM1) belonging to cluster IIIb was isolated from the tea plant. The full-length cDNA of CsUGT72AM1 is 1416 bp. It encodes 472 amino acids with a calculated molecular mass of 50.92 kDa and an isoelectric point of 5.21. The recombinant CsUGT72AM1 protein was expressed in Escherichia coli and exhibited catalytic activity toward multiple flavonoids and coniferyl aldehyde. The enzyme assay indicated that rCsUGT72AM1 could perform glycosidation of flavonols or coniferyl aldehyde in vitro to form 3-O-glucoside or 4-O-glucoside, respectively. Interestingly, this enzyme also had activities and performed multisite glycosidation toward flavanones. The consistent products were confirmed to be naringenin-7-O-glucoside and -4'-O-glucoside by the nuclear magnetism assay. In addition, in the enzyme assay with cyanidin as the substrate, the results suggested that the glycosylated activity of CsUGT72AM1 was remarkably inhibited by a high concentration of anthocyanins. The above results indicate that CsUGT72AM1 may be involved in the metabolism of flavonol, flavanone, anthocyanin, and lignin.

Effects of a short-term feed restriction on growth performance, blood metabolites and hepatic IGF-1 levels in growing rabbits

<p class="Abstract">A total of 144 weaned hybrid HYLA rabbits (40-day-old) were randomly divided into 4 groups, to investigate the effects of the intensity of one week’s feed restriction on short- and medium-term growth performance, blood metabolites and hepatic IGF-1 in growing rabbits. Restricted groups were fed with 30% (Group L30), 50% (Group L50) 70% (Group L70) of ad libitum feeding for 1 wk and then fed ad libitum until the end of the experiment (75 d of age). The control group (Group AL) was fed ad libitum throughout the experiment. Total feed intake (–15.8%) and feed conversion ratio (–13.2%) were lower in the L50 than in the AL group (P&lt;0.05), but no difference was found between the L30, L70 and AL groups (P&gt;0.05) for these parameters. Total weight gain did not significantly differ among the 4 experimental groups (38.5 g/d; P&gt;0.05). At the end of the feed restriction period, the total serum protein level (P=0.01) was higher in restricted rabbits than AL rabbits (P&lt;0.01), while the hepatic IGF-1 level was lower in L30 and L50 groups than in the 2 other groups (P&lt;0.001). However, no difference remained between groups at the end of the experiment. In contrast, calcium, triglycerides, alkaline phosphatase, urea nitrogen and total cholesterol levels were similar between groups (P&gt;0.05) throughout the experiment. In conclusion, a short-term feed restriction improves feed conversion ratio in a lasting way, transiently alters serum protein and IFG-1 levels and leads to compensatory growth in growing rabbits.</p>

Six phenylalanine ammonia-lyases from Camellia sinensis: Evolution, expression, and kinetics

Phenylalanine ammonia-lyase (PAL), the branch point enzyme controlling the flow of primary metabolism into second metabolism, converts the L-phenylalanine (L-Phe) to yield cinnamic acid. Based on the sequencing data available from eight transcriptome projects, six PAL genes have been screened out, cloned, and designated as CsPALa-CsPALf. The phylogenetic tree showed that CsPALs were divided into three subgroups, PALa and PALb, PALc and PALd, and PALe and PALf. All six CsPALs exhibited indiscriminate cytosolic locations in epidermis cells and mesophyll cells. Then, the expression profiles of six PAL genes were qualitatively investigated and they displayed tissue-/induced-expression specificity in several tissues or under different exogenous treatments. Furthermore, in vitro enzymatic assays showed that all six recombinant proteins were characterized by the strict substrate specificity toward L-Phe, but no activity toward L-Tyr, and they displayed subtle differences in kinetics and enzymatic properties. These results indicate that CsPALs play both distinct and overlapping roles in plant growth and responses to environmental cues.

Identification of a Flavonoid Glucosyltransferase Involved in 7-OH Site Glycosylation in Tea plants (Camellia sinensis)

Flavonol glycosides, which are often converted from aglycones in a process catalyzed by UDP-glycosyltransferases (UGTs), play an important role for the health of plants and animals. In the present study, a gene encoding a flavonoid 7-O-glycosyltransferase (CsUGT75L12) was identified in tea plants. Recombinant CsUGT75L12 protein displayed glycosyltransferase activity on the 7-OH position of multiple phenolic compounds. In relative comparison to wild-type seeds, the levels of flavonol-glucosides increased in Arabidopsis seeds overexpressing CsUGT75L12. In order to determine the key amino acid residues responsible for the catalytic activity of the protein, a series of site-directed mutagenesis and enzymatic assays were performed based on the 3D structural modeling and docking analyses. These results suggested that residue Q54 is a double binding site that functions as both a sugar receptor and donor. Residues H56 and T151, corresponding to the basic active residues H20 and D119 of VvGT1, were not irreplaceable for CsUGT75L12. In addition, residues Y182, S223, P238, T239, and F240 were demonstrated to be responsible for a ‘reversed’ sugar receptor binding model. The results of single and triple substitutions confirmed that the function of residues P238, T239, and F240 may substitute or compensate with each other for the flavonoid 7-O-glycosyltransferase activity.

[Dynamics of F1 antibody responses to Yersinia pestis infection in Rhombomys opimus]

Objective: To observe the dynamics of antibody response in great gerbils infected with Yersinia pestis in experiment. Method: A total of 211 great gerbils were captured in the southern margin of plague natural focus of Junggar Basin of the Xinjiang Uygur Autonomous Region in 2011. Among them, there were 167 great gerbils without infection of Y. pestis and 44 great gerbils infected by Y.pestis. Y.pestis No. 2504 was employed for this experimental strain, which was strong toxic strain with negativity in the reduction experiment of nitrate. 35 great gerbils without the infection of Y. pestis were divided randomly and averagely into 7 groups including 6 experimental groups and 1 control group. Great gerbils in the 1st to 6th experimental groups were exposed first with 1 × 10(6)-1 × 10(11) CFU/ml of bacterial fluid with 10 times of gradient dilution; groin areas of great gerbils in the control group were injected subcutaneously with physiological saline; and the amount of infection was all 1 ml. 17 great gerbils infected with Y. pestis and the first detection of F1-antibody titer in 1∶256-1∶4 096 were grouped according to F1-antibody titer: group 1∶4 096 (n=4), group 1∶2 048 (n=4), group 1∶1 024 (n=3), group 1∶512 (n=3) and group 1∶256 (n=3); and blood in caudal regions was collected in asepsis for the detection of F1-antibody, with a total of 5 times. 9 great gerbils which were selected from the remaining great gerbils infected with Y. pestis and detected F1-antibody negative 2 times were exposed 1×10(6) CFU/ml of bacterial fluid for the second infection, with the amount of infection being 1 ml. Blood in caudal regions of great gerbils after the first and second infection were collected for the detection of plague F1-antibody on the 3rd, 5th, 7th, 15th, 30th, 60th, 90th and 120th day after infection. Declined regression models for great gerbils' antibodies were established with unary linear regression equation; declined change diagrams for the antibodies were drawn to observe the declined F1-antibody after great gerbils were exposed to Y. pestis. Results: In great gerbils with the first infection of Y. pestis, antibodies were detected in the 1 × 10(6)-1 × 10(8) CFU/ml of group on the 30th, 15th and 15th day, respectively; the positive rates of antibody were 1/4, 3/4 and 4/5, respectively; the group 1×10(7) and 1× 10(8) CFU/ml reached to the highest antibody titer with 1∶256 on the 120th day; antibodies were revealed in the group 1×10(9), 1×10(10) and 1×10(11) CFU/ml from the 5th to 7th day when the seroconversion of all antibodies was observed; group 1×10(11) CFU/ml reached to the highest antibody titer on the 120th day with 1∶4 096. In the great gerbils with the second exposure to Y.pestis, positive antibodies were detected on the 3rd day with the positive rate being 2/9; and the highest antibody titer with 1∶2 048 was noted on the 90th day. Unary linear regression equation of declined F1 antibody of great gerbils was y=0.045x- 0.321 (F=115.40, P< 0.001), and the shortest duration for F1-antibody titer declining from 1∶4 096 to 0 was 140 d and the longest duration 200 d. Conclusion: Great gerbils infected with the high concentration of Y. pestis fluid show shorter duration in producing F1-antibody, the antibody positive rate is also higher, and the highest antibody titer can reach 1∶4 096. The great gerbils could hold the plague F1 antibodies for a long time which was about 140 to 200 days from the highest titer.

Superconductivity in HfTe5 across weak to strong topological insulator transition induced via pressures

Recently, theoretical studies show that layered HfTe₅ is at the boundary of weak & strong topological insulator (TI) and might crossover to a Dirac semimetal state by changing lattice parameters. The topological properties of 3D stacked HfTe₅ are expected hence to be sensitive to pressures tuning. Here, we report pressure induced phase evolution in both electronic & crystal structures for HfTe₅ with a culmination of pressure induced superconductivity. Our experiments indicated that the temperature for anomaly resistance peak (Tp) due to Lifshitz transition decreases first before climbs up to a maximum with pressure while the Tp minimum corresponds to the transition from a weak TI to strong TI. The HfTe₅ crystal becomes superconductive above ~5.5 GPa where the Tp reaches maximum. The highest superconducting transition temperature (Tc) around 5 K was achieved at 20 GPa. Crystal structure studies indicate that HfTe₅ transforms from a Cmcm phase across a monoclinic C2/m phase then to a P-1 phase with increasing pressure. Based on transport, structure studies a comprehensive phase diagram of HfTe₅ is constructed as function of pressure. The work provides valuable experimental insights into the evolution on how to proceed from a weak TI precursor across a strong TI to superconductors.