An auxin signaling gene BnaA3.IAA7 contributes to improved plant architecture and yield heterosis in rapeseed

Plant architecture is the key factor affecting overall yield in many crops. The genetic basis underlying plant architecture in rapeseed (Brassica napus), a key global oil crop, is elusive. We characterized an ethyl methanesulfonate (EMS)-mutagenized rapeseed mutant, sca, which had multiple phenotypic alterations, including crinkled leaves, semi-dwarf stature, narrow branch angles and upward-standing siliques. We identified the underlying gene, which encodes an Aux/IAA protein (BnaA3.IAA7). A G-to-A mutation changed the glycine at the 84^th position to glutamic acid (G84E), disrupting the conserved degron motif GWPPV and reducing the affinity between BnaA3.IAA7 and TIR1 (TRANSPORT INHIBITOR RESPONSE 1) in an auxin dosage-dependent manner. This change repressed the degradation of BnaA3.IAA7 and therefore repressed auxin signaling at low levels of auxin that reduced the length of internodes. The G84E mutation reduced branch angles by enhancing the gravitropic response. The heterozygote +/sca closely resembled a proposed ideal plant architecture, displaying strong yield heterosis through single-locus overdominance by improving multiple component traits. Our findings demonstrate that a weak gain-of-function mutation in BnaA3.IAA7 contributes to yield heterosis by improving plant architecture and would be valuable for breeding superior rapeseed hybrid cultivars and such a mutation may increase the yield in other Brassica crops.

[Investigation on the status of multidrug-resistant gram-negative bacteria induced by occupational exposure among medical staff in ICU]

Objective: To understand the natural carriage status of multidrug resistant gram-negative bacteria in ICU medical personmel and control growp of 69 hospitals in Tianjin. Methods: From April 2007 to October 2016, 2902 samples of nasal vestibule and hand swabs were collected from 1296 ICU medical personmel and 155 non medical personmel (control group) , and 14 kinds of antimicrobial agents were used to test the sensitivity of gram-negative bacilli. Results: 332 Gram-negative bacteria were isolated from medical personmel, of which 139 were multidrug resistant; 70 gram-negative bacteria were isolated from control group, and 20 of which were multidrug resistant. There was no significant difference (P>0.05) in the incidence of nasal vestibular colonization between medical personmel group (231/1296) and control group (32/155) . The control group (38/155) had a higher rate of hand bacteria carriage than medical staff group (101/1296) (P<0.01) . The proportion of multidrug resistant gram-negative bacteria was 28.57% (20/70) in control group, which was significantly lower than medical personmel group (41.87%, 139/332) (P<0.05) . Conclusion: For the nasal vestibule, the medical personnel and control guoup have the same gram-negative bacteria carrying rate, but the multidrug resistant bacteria isolation rate from the medical staff group are significantly higher which may due to vocational contamination of pathogen in ICU; while the gram-negative bacteria in the hands of the medical staff group are significantly lower than those of the control group, which might attribute to the difference of hand sanitation technique of two groups.

[Skeletal muscle MRI of lower limbs in patients with facioscapulohumeral dystrophy]

Objective: To investigate MRI features of lower limbs in patients with facioscapulohumeral dystrophy(FSHD). Methods: The clinical manifestations, myopathological findings and MRI images of 5 FSHD patients were studied retrospectively from June 2016 to December 2017 at Department of Neurology, Henan Provincial People's Hospital, 3 of which had a family history. Analysis of T(1)WI images enabled us to describe muscle fatty infiltration and STIR images to describe muscle edema. Each muscle was scored according to its fatty degeneration (fat replacement score range from 0-4). Results: The 5 patients were all asymmetrically involved. At the thigh level, the hamstrings were more affected than anterior muscles in 4 patients, and anterior muscles were more affected than hamstrings in only 1 patient. The most affected thigh muscles were usually the adductor magnus, semimembranosus, semitendinosus, femoral biceps long head and vastus medialis muscles (average fat replacement score of each muscle was more than 3). The calves were less affected than thighs.The average fat replacement score of the calf muscles was 1.0 for soleus, 0.9 for medial gastrocnemius, 0.8 for tibialis anterior, and 0.4 for lateral gastrocnemius. There was no fatty infiltration in peroneus and tibialis posterior. 4 out of 5 patients had edema in the lower limb muscles. Conclusion: Asymmetric involvement is a definitely helpful clue suggesting FSHD, and edema is a common phenomenon. At the thigh level, no unique imaging pattern can be highlighted in all the FSHD patients, overall, the hamstring, adductor magnus and vastus medialis are usually the most severely affected muscles. The calf muscles are less affected than the thigh muscles or spared. Soleus, medial gastrocnemius, and tibialis anterior are preferentially involved at the calf level.

Azimuthal Anisotropy of Heavy-Flavor Decay Electrons in p-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

Angular correlations between heavy-flavor decay electrons and charged particles at midrapidity (|η|<0.8) are measured in p-Pb collisions at sqrt[s_{NN}]=5.02  TeV. The analysis is carried out for the 0%-20% (high) and 60%-100% (low) multiplicity ranges. The jet contribution in the correlation distribution from high-multiplicity events is removed by subtracting the distribution from low-multiplicity events. An azimuthal modulation remains after removing the jet contribution, similar to previous observations in two-particle angular correlation measurements for light-flavor hadrons. A Fourier decomposition of the modulation results in a positive second-order coefficient (v_{2}) for heavy-flavor decay electrons in the transverse momentum interval 1.5<p_{T}<4  GeV/c in high-multiplicity events, with a significance larger than 5σ. The results are compared with those of charged particles at midrapidity and those of inclusive muons at forward rapidity. The v_{2} measurement of open heavy-flavor particles at midrapidity in small collision systems could provide crucial information to help interpret the anisotropies observed in such systems.

[Characteristic and function of peripheral blood mononuclear cells-induced macrophages in patients with myelodysplastic syndrome]

目的

观察骨髓增生异常综合征（MDS）患者单个核细胞诱导的巨噬细胞的功能，分析其与MDS疾病发展的关系。

方法

以2014年9月至2015年12月天津医科大学总医院血液科24例MDS患者为病例组，以15名健康志愿者为正常对照组。收集外周血标本并分离单个核细胞，体外以GM-CSF诱导分化形成巨噬细胞。在光学显微镜下观察巨噬细胞的形态；使用流式细胞术检测巨噬细胞的数量及其表面受体CD206、SIRPα的表达水平；分别采用流式细胞术和免疫荧光显微镜检测巨噬细胞的吞噬功能。

结果

①MDS来源的巨噬细胞形态较正常对照差（形态不规则、细胞体积小、异形明显、无足突、数量减少），MDS外周血单个核细胞转化为巨噬细胞的转化率为（5.17±3.47）%，显著低于正常对照组的（66.18±13.43）%（t=3.529，P=0.001）；②MDS来源的巨噬细胞表面识别受体CD206的表达水平[（9.73±2.59）%]显著低于正常对照组[（51.15±10.82）%]（t=4.551，P<0.001），SIRPα的表达水平[（0.51±0.09）%]显著低于正常对照组[（0.77±0.06）%]（t=2.102，P=0.043）；③MDS来源的巨噬细胞吞噬免疫微球的吞噬指数、吞噬百分率分别为0.45±0.08、（23.69±3.22）%，显著低于正常对照组的0.92±0.07、（42.75±2.13）%（P值均<0.05），MDS来源的巨噬细胞吞噬单个核细胞的吞噬指数（0.24±0.04）显著低于正常对照组（0.48±0.96，t=3.464，P=0.001）。

结论

MDS患者外周血单个核细胞诱导形成巨噬细胞能力下降，吞噬识别受体减少，吞噬能力减弱。

[Prediction of pelvic floor muscle function in stress urinary incontinence]

Objective: To explore the predictive effect of pelvic floor muscle function on stress urinary incontinence (SUI) . Methods: A total of 258 women in gynecological outpatients at Fuzhou General Hospital were evaluated the pelvic floor muscle function by intravaginal manometery, then all of outpatients were divided into urinary incontinence group and non-incontinence group, and compared pelvic floor muscle function and clinical characteristic to establish prediction model of SUI by classification tree and analyse the predictive role of pelvic floor muscle function for SUI. Results: There were significant difference in body mass index [BMI; (22.8±2.9) vs (21.5±2.7) kg/m², P<0.05], maximum newborn weight [ (3 396±424) vs (3 284±384) g, P<0.05] between urinary incontinence group (n=114) and non-incontinence group (n=144) . However, there were no significant differences in age, parity and mode of delivery between two groups (all P>0.05) . There were significant differences (all P<0.01) in maximum vaginal pressure [ (21±7) vs (35±9) mmHg (1 mmHg=0.133 kPa) ], average pressure [ (13±7) vs (23±9) mmHg], fatigue [ (-65±20) % vs (-46±17) %] and collecting time [ (1.0±0.6) vs (0.8±0.5) s] between two groups. Prediction model, which obtained by classification tree analysis with the affecting factors of SUI (including BMI, maximum vaginal pressure, fatigue and collecting time) , suggested that the incidence of SUI was 88.6% (70/79) , when maximum vaginal pressure ≤26.2 mmHg. While, when maximum vaginal pressure was greater than 28.2 mmHg, there was no occurrence of SUI (0/7) . But it would increase, when BMI >22.6 kg/m². Conclusions: The occurrence of SUI is related to the BMI and pelvic floor muscles function. It would increase the risk of SUI with vaginal maximum pressure (≤26.2 mmHg) and BMI (>22.6 kg/m²) . While there is almost no SUI, while vaginal maximum pressure >28.2 mmHg. To select high-risk group of SUI and intervene early according to the prediction model, which may be make sense of reducing incidence of SUI.

[Investigation on the status of multidrug-resistant gram-negative bacteria induced by occupational exposure among medical staff in ICU]

Objective: To understand the natural carriage status of multidrug resistant gram-negative bacteria in ICU medical personmel and control growp of 69 hospitals in Tianjin. Methods: From April 2007 to October 2016, 2902 samples of nasal vestibule and hand swabs were collected from 1296 ICU medical personmel and 155 non medical personmel (control group) , and 14 kinds of antimicrobial agents were used to test the sensitivity of gram-negative bacilli. Results: 332 Gram-negative bacteria were isolated from medical personmel, of which 139 were multidrug resistant; 70 gram-negative bacteria were isolated from control group, and 20 of which were multidrug resistant. There was no significant difference (P>0.05) in the incidence of nasal vestibular colonization between medical personmel group (231/1296) and control group (32/155) . The control group (38/155) had a higher rate of hand bacteria carriage than medical staff group (101/1296) (P<0.01) . The proportion of multidrug resistant gram-negative bacteria was 28.57% (20/70) in control group, which was significantly lower than medical personmel group (41.87%, 139/332) (P<0.05) . Conclusion: For the nasal vestibule, the medical personnel and control guoup have the same gram-negative bacteria carrying rate, but the multidrug resistant bacteria isolation rate from the medical staff group are significantly higher which may due to vocational contamination of pathogen in ICU; while the gram-negative bacteria in the hands of the medical staff group are significantly lower than those of the control group, which might attribute to the difference of hand sanitation technique of two groups.

Early Focal Segmental Glomerulosclerosis as a Cause of Delayed Graft Function With Combined Acute Antibody Rejection: A Case Report

Focal segmental glomerulosclerosis (FSGS) is the most common form of post-transplant glomerulonephritis. We describe a case where a biopsy proved that early recurrence of FSGS on postoperative day 1 was the cause of delayed graft function. A 39-year-old man, on hemodialysis for 15 years due to polycystic kidney disease, received a cadaveric renal transplantation. On postoperative day 1, his hourly urine output decreased from 700-800 mL to 50 mL. The graft biopsy showed a mild acute kidney injury confusing nephrotic syndrome. On postoperative day 45, his creatinine level increased to 3.02 mg/dL with severe proteinuria. A kidney biopsy showed focal segmental glomerulosclerosis. On postoperative day 120, his creatinine level elevated again, concomitant with proteinuria. A kidney biopsy showed FSGS with antibody-mediated rejection. After plasmapheresis, his creatinine level decreased to 1.3 mg/dL with mild proteinuria. Once active in the allograft, de novo FSGS is a potentially aggressive process. In this case, it could be managed because of an accurate diagnosis and appropriate treatment.

Motivation for physical activity and the moderating effect of cancer diagnosis: A nationally representative cross-sectional study

The aim of this study was to investigate associations between types of motivation for physical activity and self-reported weekly aerobic moderate-to-vigorous physical activity (MVPA) in the 2012 and 2014 waves of the nationally representative Health Information National Trends Survey 4 (n = 7307). We further explored differential associations between MVPA and types of motivation for physical activity by cancer survivor status. We found that those who were more motivated by "getting enjoyment from exercise" reported 26.4% more MVPA (+49.8 min/week) than those who were less motivated by this factor, adjusting for covariates (p = 0.025). Conversely, those who were more motivated by "concern over the way you look" reported 22.1% less MVPA (-55.5 min/week) than those who were less motivated by this factor, adjusting for covariates (p = 0.002). We found no evidence for a relationship between motivation from either "pressure from others" or "feeling guilty when you skip exercising" and MVPA. We identified a significant interaction for "feeling guilty when you skip exercising" and cancer survivor status, adjusting for covariates (p = 0.034). Cancer survivors who reported being more motivated by "feeling guilty when you skip exercising" reported 36.2% less MVPA (-71.75 min/week) than those who were less motivated by this factor; there was no statistically reliable difference in those without a history of cancer. Findings are concordant with previous literature highlighting the primacy of enjoyment for physical activity adherence. There is a need for further inquiry into guilt-related motivation for physical activity among cancer survivors, as it may have a unique, negative impact in this population.

Sustained pain hypersensitivity in the stressed colon: Role of mast cell-derived nerve growth factor-mediated enteric synaptic plasticity

BACKGROUND

Sustained pain hypersensitivity is the hallmark of stressed colon which could be partially explained by central sensitization with synaptic plasticity, the key mechanism of memory. We previously identified that synaptic plasticity of enteric nerve system (ENS) contributed to peripheral pain maintaining in the gut. However, the mechanisms of enteric "memory" formation remain elusive.

METHODS

In this study, rats were exposed to water avoidance stress (WAS) or sham stress (SS), with cromolyn sodium or physiological saline injected intraperitoneally 30 minutes before stress every day. The abdominal withdrawal reflex scores, mesenteric afferent nerve activity, enteric neural c-fos expression, and enteric synaptic plasticity were assessed, and mast cell infiltration and degranulation. Furthermore, colonic mucosal mediators-induced enteric synaptic plasticity and the role of mast cell-derived nerve growth factor (NGF), tryptase, and histamine were investigated via ex vivo longitudinal muscle-myenteric plexus (LMMP) organotypic culture.

KEY RESULTS

It is shown that mast cell stabilizing inhibited WAS-induced visceral hypersensitivity through enhancing visceral pain threshold, decreasing spontaneous and distention-induced mesenteric afferent firing, and downregulating enteric neural activation (c-fos). Importantly, WAS led to evident enteric synaptic plasticity, but decreased by cromolyn. Water avoidance stress-derived mucosal supernatants markedly enhanced the c-fos expression and enteric synaptic plasticity in LMMP tissues, which could be eliminated by mast cell inhibition or NGF neutralization, but not tryptase or histamine blocking.

CONCLUSIONS & INFERENCES

In conclusion, mast cells/NGF pathway may be the key regulator of synaptic plasticity of ENS and participate in the formation of chronic stress-induced sustained visceral hypersensitivity.

ELF3 is an antagonist of oncogenic-signalling-induced expression of EMT-TF ZEB1

Background: Epithelial-to-mesenchymal transition (EMT) is a key step in the transformation of epithelial cells into migratory and invasive tumour cells. Intricate positive and negative regulatory processes regulate EMT. Many oncogenic signalling pathways can induce EMT, but the specific mechanisms of how this occurs, and how this process is controlled are not fully understood. Methods: RNA-Seq analysis, computational analysis of protein networks and large-scale cancer genomics datasets were used to identify ELF3 as a negative regulator of the expression of EMT markers. Western blotting coupled to siRNA as well as analysis of tumour/normal colorectal cancer panels was used to investigate the expression and function of ELF3. Results: RNA-Seq analysis of colorectal cancer cells expressing mutant and wild-type β-catenin and analysis of colorectal cancer cells expressing inducible mutant RAS showed that ELF3 expression is reduced in response to oncogenic signalling and antagonizes Wnt and RAS oncogenic signalling pathways. Analysis of gene-expression patterns across The Cancer Genome Atlas (TCGA) and protein localization in colorectal cancer tumour panels showed that ELF3 expression is anti-correlated with β-catenin and markers of EMT and correlates with better clinical prognosis. Conclusions: ELF3 is a negative regulator of the EMT transcription factor (EMT-TF) ZEB1 through its function as an antagonist of oncogenic signalling.

Feasibility, Safety, and Periprocedural Complications Associated with Endovascular Treatment of Ruptured Intracranial Aneurysms according to the Depth of Anesthesia

BACKGROUND AND PURPOSE

The aim of the present study was to report the feasibility, safety, and periprocedural complications associated with EVT of ruptured intracranial aneurysms according to the depth of anesthesia. In most centers, endovascular treatment of intracranial aneurysm is performed under general anesthesia.

MATERIALS AND METHODS

Between March 2011 and December 2016, a total of 183 consecutive patients with 183 aneurysms were treated endovascularly at the authors' center. The data about the depth of anesthesia (local anesthesia, conscious sedation, deep sedation, and general anesthesia), procedural details, and clinical and radiologic outcomes were reviewed.

RESULTS

A total of 183 consecutive patients with 183 aneurysms (mean age, 60.2 ± 14.8 years; 54 men and 129 women) were successfully treated. Of these, 70 (38.3%) patients underwent endovascular treatment under local anesthesia, 33 (18.0%) patients underwent endovascular treatment under conscious sedation, 78 (42.6%) patients underwent endovascular treatment under deep sedation, and only 2 (1.1%) patients underwent endovascular treatment under general anesthesia. For patients who presented with Hunt and Hess grades 1, 2, 3, 4, and 5, 75%, 59.6%, 59.1%, 53.3%, and 35.3% were treated under local anesthesia or conscious sedation, respectively. The procedure-related complication rates amounted to 8.7% (16/183, with 11 thromboembolic complications and 5 intraprocedural ruptures) overall, and 7.7% (14/183) of complications were symptomatic events. In the patients with good clinical grade (Hunt and Hess 1 or 2), the procedure-related complication rate was 4.1% (4/97), and all complications were symptomatic events under local anesthesia or conscious sedation.

CONCLUSIONS

In the authors' experience, local anesthesia or conscious sedation seemed safe and feasible for the patients with good clinical grade SAH.

Pressure-Induced Superconductivity in Elemental Ytterbium Metal

Ytterbium (Yb) metal is divalent and nonmagnetic (4f^{14} configuration). Under pressure its valence increases significantly leading to the expectation that magnetic instabilities and other highly correlated electron effects may appear before a stable trivalent state is reached (4f^{13} configuration). We carried out electrical resistivity and ac magnetic susceptibility measurements to 179 GPa over the temperature range 1.4-295 K. No evidence for magnetic order is observed. However, Yb becomes a superconductor at 86 GPa with T_{c}≃1.4  K, increasing to 4.6 K at 179 GPa. X-ray absorption spectroscopy shows that Yb remains mixed valent to at least 125 GPa, pointing to an active role of f electrons in the emergence of superconductivity in this simple, elemental solid.

Core-shell patterning of synthetic hydrogels via interfacial bioorthogonal chemistry for spatial control of stem cell behavior

A new technique is described for the patterning of cell-guidance cues in synthetic extracellular matrices (ECM) for tissue engineering applications. Using s-tetrazine modified hyaluronic acid (HA), bis-trans-cyclooctene (TCO) crosslinkers and monofunctional TCO conjugates, interfacial bioorthogonal crosslinking was used to covalently functionalize hydrogels as they were synthesized at the liquid-gel interface. Through temporally controlled introduction of TCO conjugates during the crosslinking process, the enzymatic degradability, cell adhesivity, and mechanical properties of the synthetic microenvironment can be tuned with spatial precision. Using human mesenchymal stem cells (hMSCs) and hydrogels with a core-shell structure, we demonstrated the ability of the synthetic ECM with spatially defined guidance cues to modulate cell morphology in a biomimetic fashion. This new method for the spatially resolved introduction of cell-guidance cues for the establishment of functional tissue constructs complements existing methods that require UV-light or specialized equipment.

Virtual Planning and 3D printing modeling for mandibular reconstruction with fibula free flap

Background

This study was to evaluate the use of virtual planning and 3D printing modeling in mandibular reconstruction and compare the operation time and surgical outcome of this technique with conventional method.

Material and Methods

Between 2014 and 2017, 15 patients underwent vascularized fibula flap mandibular reconstruction using virtual planning and 3D printing modeling. Titanium plates were pre-bent using the models and cutting guides were used for osteotomies. 15 patients who underwent mandibular reconstruction using fibula flap without aid of virtual planning and 3D printing models were selected as control group. The operation time was recorded and compared in two groups. Accuracy of reconstruction was measured by superimposing the preoperative image onto the postoperative image of mandible. The selected bony landmark, distance and angle were measured.

Results

The mean total operation time and reconstruction time were 1.60±0.37 and 5.54±0.50 hours in computer-assisted group, respectively; These were 2.58±0.45 and 6.54±0.70 hours in conventional group, respectively. Both operation time and reconstruction time were shorter in computer-assisted group. The difference between the preoperative and postoperative intercondylar distances, intergonial angle distances, anteroposterior distances and gonial angles were 2.92±1.15 and 4.48±1.41mm, 2.93±1.19 and 4.79±1.48mm, 4.31±1.24 and 5.61±1.41mm, 3.85±1.68° and 5.88±2.12° in the computer-assisted and conventional group, respectively. The differences between the preoperative and postoperative mandible is smaller in the computer-assisted group.

Conclusions

Virtual planning and 3D printing modeling have the potential to increase mandibular reconstruction accuracy and reduce operation time. we believe that this technology for mandibular reconstruction in selected patients will become a used method and improve the quality of reconstruction.

Key words:Mandibular reconstruction, fibula flap, virtual planning, computer-assisted design, 3D printing.

D-Meson Azimuthal Anisotropy in Midcentral Pb-Pb Collisions at sqrt[s]_{NN}=5.02 TeV

The azimuthal anisotropy coefficient v_{2} of prompt D^{0}, D^{+}, D^{*+}, and D_{s}^{+} mesons was measured in midcentral (30%-50% centrality class) Pb-Pb collisions at a center-of-mass energy per nucleon pair sqrt[s_{NN}]=5.02  TeV, with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays at midrapidity, |y|<0.8, in the transverse momentum interval 1<p_{T}<24  GeV/c. The measured D-meson v_{2} has similar values as that of charged pions. The D_{s}^{+} v_{2}, measured for the first time, is found to be compatible with that of nonstrange D mesons. The measurements are compared with theoretical calculations of charm-quark transport in a hydrodynamically expanding medium and have the potential to constrain medium parameters.

Conjugated π electron engineering of generalized stacking fault in graphene and h-BN

Generalized-stacking-fault energy (GSFE) serves as an important metric that prescribes dislocation behaviors in materials. In this paper, utilizing first-principle calculations and chemical bonding analysis, we studied the behaviors of generalized stacking fault in graphene and h-BN. It has been shown that the π bond formation plays a critical role in the existence of metastable stacking fault (MSF) in graphene and h-BN lattice along certain slip directions. Chemical functionalization was then proposed as an effective means to engineer the π bond, and subsequently MSF along dislocation slips within graphene and h-BN. Taking hydrogenation as a representative functionalization method, we demonstrated that, with the preferential adsorption of hydrogen along the slip line, π electrons along the slip would be saturated by adsorbed hydrogen atoms, leading to the moderation or elimination of MSF. Our study elucidates the atomic mechanism of MSF formation in graphene-like materials, and more generally, provides important insights towards predictive tuning of mechanic properties in two-dimensional nanomaterials.

Impact of carbohydrates on autoinducer-2 secretion of Bifidobacterium longum subsp. longum BBMN68

In this study, the regularity of autoinducer-2 (AI-2) secretion during growth and the effect of the addition of various carbohydrates on AI-2 secretion in Bifidobacterium longum subsp. longum BBMN68 were investigated. The results indicated that the AI-2 concentration reached its highest level (2536·60 nmol l^-1 ) at the early stationary growth phase, and then decreased to 1263·72 nmol l^-1 at the late stationary growth phase in Bifidobacterium cultures. When the density of the cultures which mannose, fructose, sucrose and lactose had been added to reached an OD_600 nm of 1·0, the AI-2 concentrations in the cultures were 1953·84, 1637·34, 1200·99 and 1077·60 nmol l^-1 , respectively. These concentrations were all significantly higher than that of the control culture (1031·33 nmol l^-1 ). Similarly, the addition of fructooligosaccharide significantly increased the AI-2 concentrations to 2094·29 nmol l^-1 . This study provides the advanced evidence that certain carbohydrates promote the secretion of AI-2, and that this occurs at the single cell level and is therefore unaffected by cell density.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provided the advanced data of the regularity of autoinducer-2 (AI-2) secretion during growth and the promotion on AI-2 secretion of different added carbohydrates in Bifidobacterium, which may be a new potential strategy to improve the acid resistance of Bifidobacterium applied in the food industry.