Visualization of Diabetes Progression by an Activatable NIR-IIb Luminescent Probe.

Developing NIR-IIb luminescence probes with rapid visualization and a high penetration depth is essential for diabetes research. Combining a sensitizing switch with lanthanide-doped nanoparticles (LnNPs) has been employed to fabricate the NIR-IIb probes. However, these probes mainly adopt heptamethine cyanine dye as the antenna, and the NIR-IIb signal is activated by inhibiting the photoinduced electron transfer (PET) of the dye. Due to limited recognition units, this strategy makes many biomolecules undetectable, such as cysteine (Cys), which is closely related to diabetes. Herein, in this article, hemicyanine dye, NFL-OH, was verified as a new antenna to sensitize NIR-IIb emission from LnNPs. Unlike traditional cyanine dyes, hemicyanine's fluorescence intensity can also be modulated by intramolecular charge transfer (ICT), thereby expanding the range of detectable targets for NIR-IIb probes based on sensitization mechanism. Through switching the hemicyanine-sensitized NIR-IIb emission, we successfully fabricated an NFL-Cys-LnNPs' nanoprobe, which can effectively monitor Cys concentration in the liver of diabetic mice during diabetes progression and evaluate the efficacy of diabetic drugs. Our work not only presents an excellent tool for Cys imaging but also introduces new concepts for designing NIR-IIb probes.

Nomogram predictive models for adult patients with acute lymphoblastic leukaemia based on real-world treatment outcomes.

This study aimed to analyse the characteristics and treatment outcomes of adult patients with acute lymphoblastic leukaemia (ALL) and construct nomogram predictive models for prognosis prediction. Between January 2017 and June 2022, 462 adult patients with ALL were included in this retrospective analysis. Patients' ages ranged from 14 to 84 years. B-cell origin was observed in 82.7% of these patients, while 17.3% of the cases were of T-cell origin. The BCR/ABL1 fusion gene was detected in 32.9% of those with B-ALL. Complete remission was achieved in 83.7% of the patients after induction chemotherapy. The median disease-free survival (DFS) and overall survival (OS) of patients were 19.0 and 39.1 months, respectively. The 5-year DFS and OS rates were 29.5% and 41.8%, respectively. The BCR/ABL1 fusion gene had a significant adverse impact on DFS and OS when patients were treated with tyrosine kinase inhibitors (TKIs) and chemotherapy; however, this effect was eliminated when patients underwent transplantation. Multivariate analysis identified that age ≥ 35 years, white blood cell count ≥ 30 × 109/L, platelet count < 100 × 109/L, failure to achieve complete remission after induction chemotherapy, positive measurable residual disease (MRD), and absence of transplantation were independent adverse prognostic factors for DFS and/or OS. Nomogram predictive models constructed by the rms package in R software based on these prognostic factors demonstrated precise predictive value. In conclusion, adult patients with ALL experience poor survival. TKIs in combination with transplantation can eliminate the adverse effects of BCR/ABL1 fusion genes on prognosis. Nomogram predictive models were accurate for prognostic prediction and will be useful in clinical practice.

Myelodysplasia-related gene mutations are associated with favorable prognosis in patients with TP53-mutant acute myeloid leukemia.

This study aimed to examine the characteristics and treatment outcomes of patients with TP53-mutant acute myeloid leukaemia (AML) and to explore potential prognostic factors. This retrospective analysis included 130 patients diagnosed with TP53-mutant AML at the Fujian Medical University Union Hospital between January 2016 and June 2023. Patients' ages ranged from 17 to 80 years, with a median age of 59 years. The proportions of de novo, therapy-related, and secondary AML cases were 71.5%, 7.7%, and 20.8%, respectively. Complex karyotypes were observed in 60.6% of patients, and the proportions of -5 or del(5q), -7 or del(7q), and - 17 or del(17p) were 41.7%, 27.9% and 14.4%, respectively. DNA methylation- and myelodysplasia-related (MR) gene mutations were observed in 36.9% and 25.4% of patients, respectively. These patients showed poor survival, with a median overall survival (OS) of 4.5 months, a 1-year OS rate of 32.5%, a 3-year OS rate of 18.8%, and a 5-year OS rate of 11.3%. The complete response rates for intensive chemotherapy (IC), hypomethylating agent (HMAs)-based therapies, and azacitidine plus venetoclax were 35.7%, 22.2%, and 37.5%, respectively. Patients who did or did not receive allogeneic haematopoietic stem cell transplantation (allo-HSCT) had similar prognoses (median OS: 6.0 vs. 3.9 months; P = 0.6415). Multivariate analysis indicated that MR gene mutations is an independent favorable prognostic factor of OS (HR = 0.366, 95% CI: 0.181-0.738, P = 0.005). In conclusion, patients with TP53-mutant AML have poor prognoses under current treatment strategies and MR gene mutations are associated with a more favorable survival. Therefore, further studies are needed to improve the survival rates in this population.

A near-infrared fluorescent probe with a large Stokes shift for the detection and imaging of biothiols in vitro and in vivo.

In this study, a new near-infrared (NIR) fluorescent turn-on probe featuring a large Stokes shift (198 nm) was developed for the detection of biothiols. The probe was based on a dicyanoisophorone derivative serving as the fluorophore and a 2,4-dinitrobenzenesulfonyl (DNBS) group functioning as both a recognition site and a fluorescence quencher. In the absence of biothiols, the fluorescence of the probe was low due to the photoinduced electron transfer (PET) effect between the fluorophore and DNBS. Upon the presence of biothiols, the DNBS group underwent a nucleophilic aromatic substitution reaction with the sulfhydryl group of biothiols, leading to the release of the fluorophore and a notable emission peak at 668 nm. This developed probe exhibited exceptional selectivity and sensitivity to biothiols in solution, with an impressive detection limit of 28 nM for cysteine (Cys), 22 nM for homocysteine (Hcy), and 24 nM for glutathione (GSH). Furthermore, the probe demonstrated its applicability by successfully visualizing both endogenous and exogenous biothiols in living systems.

Arsenic trioxide replacing or reducing chemotherapy in consolidation therapy for acute promyelocytic leukemia (APL2012 trial).

As all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) are widely accepted in treating acute promyelocytic leukemia (APL), deescalating toxicity becomes a research hotspot. Here, we evaluated whether chemotherapy could be replaced or reduced by ATO in APL patients at different risks. After achieving complete remission with ATRA-ATO-based induction therapy, patients were randomized (1:1) into ATO and non-ATO groups for consolidation: ATRA-ATO versus ATRA-anthracycline for low-/intermediate-risk patients, or ATRA-ATO-anthracycline versus ATRA-anthracycline-cytarabine for high-risk patients. The primary end point was to assess disease-free survival (DFS) at 3 y by a noninferiority margin of -5%; 855 patients were enrolled with a median follow-up of 54.9 mo, and 658 of 755 patients could be evaluated at 3 y. In the ATO group, 96.1% (319/332) achieved 3-y DFS, compared to 92.6% (302/326) in the non-ATO group. The difference was 3.45% (95% CI -0.07 to 6.97), confirming noninferiority (P < 0.001). Using the Kaplan-Meier method, the estimated 7-y DFS was 95.7% (95% CI 93.6 to 97.9) in ATO and 92.6% (95% CI 89.8 to 95.4) in non-ATO groups (P = 0.066). Concerning secondary end points, the 7-y cumulative incidence of relapse (CIR) was significantly lower in ATO (2.2% [95% CI 1.1 to 4.2]) than in non-ATO group (6.1% [95% CI 3.9 to 9.5], P = 0.011). In addition, grade 3 to 4 hematological toxicities were significantly reduced in the ATO group during consolidation. Hence, ATRA-ATO in both chemotherapy-replacing and -reducing settings in consolidation is not inferior to ATRA-chemotherapy (https://www.clinicaltrials.gov/, NCT01987297).

Ancient Demographics Determine the Effectiveness of Genetic Purging in Endangered Lizards.

The purging of deleterious alleles has been hypothesized to mitigate inbreeding depression, but its effectiveness in endangered species remains debatable. To understand how deleterious alleles are purged during population contractions, we analyzed genomes of the endangered Chinese crocodile lizard (Shinisaurus crocodilurus), which is the only surviving species of its family and currently isolated into small populations. Population genomic analyses revealed four genetically distinct conservation units and sharp declines in both effective population size and genetic diversity. By comparing the relative genetic load across populations and conducting genomic simulations, we discovered that seriously deleterious alleles were effectively purged during population contractions in this relict species, although inbreeding generally enhanced the genetic burden. However, despite with the initial purging, our simulations also predicted that seriously deleterious alleles will gradually accumulate under prolonged bottlenecking. Therefore, we emphasize the importance of maintaining a minimum population capacity and increasing the functional genetic diversity in conservation efforts to preserve populations of the crocodile lizard and other endangered species.

Ligilactobacillus cholophilus sp. nov., isolated from pickled potherb mustard (Brassica juncea Coss.).

Strain BD7642T was isolated from Chinese pickled potherb mustard (Brassica juncea Coss.) purchased from a local market in Shanghai, PR China. A polyphasic approach, including 16S rRNA gene sequence, housekeeping gene, average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), G+C content and phenotypic analyses, was employed to characterize strain BD7642T. Cells of the bacterium were short round rods, Gram-stain-positive, non-spore-forming and catalase-negative. The strain grew at 30-45 °C and pH 4.0-8.0. Optimum growth occurred at 35-40 °C and pH 6.0-7.0. The strain exhibited growth with salt (NaCl) concentrations of up to 5 % (w/v). The G+C content of the strain's genomic DNA was 31.37 mol%. The major fatty acids were C16 : 0, C18 : 1 c9 and summed feature 10 (C18 : 1 c11/t9/t6). 16S rRNA gene sequencing revealed that strain BD7642T represents a member of the genus Ligilactobacillus and it had high sequence similarity to Ligilactobacillus aviarius NBRC 102162T (96.73 %), Ligilactobacillus araffinosus LGM 23560 (96.66 %) and Ligilactobacillus salivarius JCM 1231T (95.82 %). The dDDH values between strain BD7642T and its phylogenetically related species within the genus Ligilactobacillus ranged from 12.6 to 25.4 %. The ANI values between strain BD7642T and its closely related taxa were far lower than the threshold (95 %-96 %) used for species differentiation. Results of phylogenetic, physiological and phenotypic characterization confirmed that strain BD7642T represents a novel species within the genus Ligilactobacillus, for which the name Ligilactobacillus cholophilus sp. nov. is proposed. The type strain is BD7642T (=CCTCC AB 2022398T=JCM 36074T).

Identification of sex pheromone of red swamp crayfish Procambarus clarkii and exploration of the chemosensory mechanism of their antennae.

Red swamp crayfish, Procambarus clarkii, is a globally invasive species, which has caused great damage to biodiversity, agriculture, and fishing. Therefore, the development of effective management methods, such as pheromone control, is necessary for biological control and biodiversity protection. However, the components of P. clarkii sex pheromones have not yet been explored, and the chemosensory mechanism of the P. clarkii antennae after stimulation by sex pheromone also remains unknown. In this study, we isolated and identified the candidate bioactive component of the female P. clarkii sex pheromone using ultrafiltration centrifugation, semi-preparative liquid phase separation and omics technologies and conducted bioassays to determine its attraction ability. Meanwhile, RNA-Seq technology was used to analyze the potential chemosensory mechanism of antennae. Our results indicated that the male P. clarkii were uniaxially attracted to the female crude conditioned water (FCW), medium fraction (MF, isolated by ultrafiltration centrifugation), and preparative fragment 6 of females (PFF6, isolated by semi-preparative liquid phase separation). Metabolomic analysis revealed the presence of 18 differential metabolites between the PFF6 and PFM6 samples, among which 15 were significantly upregulated in the PFF6 sample. Bioassay test also showed that mestranol, especially at concentrations of 10-5-10-2 mol∙l-1, could significantly attract P. clarkii males; therefore, mestranol was identified as the candidate sex pheromone component of P. clarkii females. Furthermore, RNA-Seq results showed that most differentially expressed genes (DEGs) enriched in lipid metabolism and signal transduction pathways were up-regulated in P. clarkii males. In addition, high expressions of Ca2+-binding protein and ion transporting ATPases may enhance the sensitivity of the antennae of P. clarkii males towards sex pheromones. Our study provides data on P. clarkii sex pheromone composition and reveals the molecular mechanism of sex pheromone response in P. clarkii. Moreover, our study provides a referable method for the isolation of candidate bioactive molecules from the P. clarkii sex pheromone.

Levan from Leuconostoc citreum BD1707: production optimization and changes in molecular weight distribution during cultivation.

BACKGROUND: Levan is a well-known homopolymer of fructose composed predominantly of ß-(2, 6) fructofuranosyl linkages in the backbone with occasional ß-(2, 1) linkages in the branch chains with varied applications. However, high production cost due to low yield of microbial levan has become a bottleneck for its practical applications. Furthermore, factors affecting the molecular mass of the synthesized levan by Leuconostoc spp. during prolonged cultivation is not fully elucidated. METHODS: The cultivation condition for Leuconostoc citreum BD1707 to synthesize levan was optimized by single-factor experiments and subsequently with response surface methodology (RSM). The average molecular weight (Mw) of levan synthesized by the strain L.citreum BD1707 under the optimized cultivation conditions was monitored by high-performance size exclusion chromatography (HPSEC). Finally, the enzyme with levan-degrading activity was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). RESULTS: The levan yield of BD1707 reached 34.86 g/L with a corresponding productivity of 7.47 g/L/d under the optimal cultivation conditions deduced by RSM, i.e., cultivation at 26 °C and 200 rpm for 112 h in tomato juice supplemented with 172 g/L sucrose with an initial pH value of 6.12. The Mw of levan reached a peak value of 2.320 × 107 Da at 6 h of cultivation under the optimized cultivation conditions and then gradually decreased to 8.809 × 106 Da after 120 h of cultivation. CONCLUSION: The levan yield of the strain L.citreum BD1707 could be sufficiently enhanced via cultivation condition optimization. The decrease in molecular mass of the synthesized levan was attributed predominantly to the hydrolytic activity of levansucrase secreted by L.citreum BD1707 during cultivation, with an estimated Mw of 130 KD by SDS-PAGE, while the effect of acid hydrolysis could be nearly neglected.

Isolation and Characterization of a New Fusaricidin-Type Antibiotic Produced by Paenibacillus bovis sp. nov BD3526.

Paenibacillus bovis sp. nov BD3526, isolated from raw yak (Bos grunniens) milk, was able to produce antibacterial substances against Micrococcus luteus. The antibacterial substances produced by the strain BD3526 in 3% (w/v) wheat bran broth under aerobic conditions were precipitated from the cultivated broth with ammonium sulfate at 60% saturation. Two antibacterial compounds were obtained by Sephadex LH-20 chromatography and semi-preparative reverse-phase high-performance liquid chromatography (Semi-Pre RP-HPLC). The chemical structures of the two antibacterial compounds were further elucidated by means of ultra high-performance liquid chromatography-mass spectrometer/mass spectrometer (UHPLC-MS/MS). One compound, with a molecular mass of 883.56195 Da (M + H)+, was determined to be identical in chemical structure with that of the well-known compound fusaricidin A. The other antimicrobial compound with a molecular mass of 911.59393 Da (M + H)+ was determined to be a derivative of fusaricidin A by tandem mass spectrometry and amino acid composition analysis and was designed as bovisin. Bovisin possessed the stability against acid/alkali, heat and some proteases treatment, the same with the fusaricidin A. However, the minimal inhibition concentration (MIC) of bovisin on the tested indicator including Staphylococcus aureus, Micrococcus luteus, Listeria monocytogenes and Bacillus subtilis were 50, 50, 50, 50 µg/mL, respectively, slightly higher than those of fusaricidin A (6.25, 6.25, 6.25, 12.5 µg/mL), indicating bovisin with a weaker inhibitory activity.

Effect of nucleolin on adriamycin resistance via the regulation of B-cell lymphoma 2 expression in Burkitt's lymphoma cells.

Nucleolin (NCL, C23) is an important nucleocytoplasmic multifunctional protein. Due to its multifaceted profile and high expression in cancer, NCL is considered to be a marker of drug resistance associated with chemotherapy. However, the biochemical mechanisms in which NCL suppresses drug sensitivity in several cancers have yet to be fully elucidated. This study aims to explore the effect of NCL on drug sensitivity and its potential mechanism in CA46 Burkitt's lymphoma (BL) cells. CA46 BL cells were transfected with lentiviruses carrying the NCL gene (CA46-NCL-overexpression, CA46-NCL-OE), or shRNA sequences that target the endogenous NCL gene (CA46-NCL-knockdown, CA46-NCL-KD). Adriamycin (ADM) IC50 levels for CA46-NCL-overexpressed (OE), CA46-NCL-OE control (OEC), CA46-NCL-knockdown (KD), and CA46-NCL-KD control (KDC) cells were 0.68 ± 0.06 µg/ml, 0.68 ± 0.06 µg/ml, 0.68 ± 0.06 µg/ml, and 0.30 ± 0.04 µg/ml, respectively. Apoptosis rates were significantly increased following NCL KD, whereas the opposite effect was noted in OE cells. A significant reduction of B-cell lymphoma 2 (Bcl-2) mRNA and protein levels in KD cells was observed, while OE cells displayed the opposite effect. The stability of Bcl-2 mRNA was influenced by NCL levels, the half-life of which was extended after NCL-OE, whereas it was reduced in KD cells. Finally, results of RNA-immunoprecipitation assays indicated that NCL could bind to Bcl-2 mRNA in CA46 cells. Taken together, these results suggested that NCL could mediate Bcl-2 expression and stability, and thus enhance ADM resistance in CA46 BL cells.

Impacts of maternal characteristics and temperature on juvenile survival in the crocodile lizard: Implications for conservation.

Captive breeding is an important conservation measure that may restore and enhance wild populations of rare and endangered species. Multiple anthropogenic hazards have brought the crocodile lizard, Shinisaurus crocodilurus, to the brink of extinction. We initiated a captive breeding program and quantified female reproductive traits, including reproductive timing, litter size, litter mass, and neonate size. To identify the internal and external factors affecting female reproductive function, we then analyzed how maternal age is related to body size, temperature, and female reproductive traits. We found that larger female crocodile lizards produced more offspring than smaller ones, as both litter size and litter mass were positively related to maternal body size. In contrast, neonate size was independent of maternal body size. Maternal reproductive output varied among different age groups. Young and old females had significantly smaller living litter size and mass than middle-aged females. Among captive females, one-third exhibited early parturition in autumn and winter instead of the following spring, a pattern probably associated with higher ambient temperatures in captivity. Although female reproductive output and neonatal body size did not differ between early- and normal-parturition females, offspring from the former group died earlier than those from the latter. Our study highlights the danger of climate change in hastening parturition, a phenomenon that could significantly hamper neonate survival and impede population recruitment.

Molecular and Functional Study of a Branching Sucrase-Like Glucansucrase Reveals an Evolutionary Intermediate between Two Subfamilies of the GH70 Enzymes.

Glucansucrases (GSs) in glycoside hydrolase family 70 (GH70) catalyze the synthesis of α-glucans from sucrose, a reaction that is widely seen in lactic acid bacteria (LAB). These enzymes have been implicated in many aspects of microbial life. Products of GSs have great commercial value as food supplements and medical materials; therefore, these enzymes have attracted much attention from both science and industry. Certain issues concerning the origin and evolution of GSs are still to be addressed, although an increasing number of GH70 enzymes have been characterized. This study describes a GS enzyme with the appearance of a branching sucrase (BrS). Structural analysis indicated that this GS enzyme produced a type of glucan composed of an α-(1→6) glucosidic backbone and α-(1→4) branches, as well as a considerable amount of α-(1→3) branches, distinguishing it from the GSs identified so far. Moreover, sequence-based analysis of the catalytic core of this enzyme suggested that it might be an evolutionary intermediate between the BrS and GS subgroups. These results provide an evolutionary link between these subgroups of GH70 enzymes and shed new light on the origination of GSs.IMPORTANCE GH70 GSs catalyze the synthesis of α-glucans from sucrose, a reaction that is widely seen in LAB. Products of these enzymes have great commercial value as food supplements and medical materials. Moreover, these enzymes have attracted much attention from scientists because they have potential in tailored synthesis of α-glucans with desired structures and properties. Although more and more GSs have been characterized, the origin and evolution of these enzymes have not been well addressed. This study describes a GS with the appearance of a BrS (i.e., high levels of similarity to BrSs in sequence analysis). Further analysis indicated that this enzyme synthesized a type of insoluble glucan composed of an α-(1→6) glucosidic backbone and many α-(1→4)- and α-(1→3)-linked branches, the linkage composition of which has rarely been reported in the literature. This BrS-like GS enzyme might be an evolutionary intermediate between BrS and GS enzymes.

The Construction and Identification of Induced Pluripotent Stem Cells Derived from Acute Myelogenous Leukemia Cells.

OBJECTIVE: The present study aimed to establish an induced pluripotent stem cell (iPSC) line from acute myelogenous leukemia (AML) cells in vitro and identify their biological characteristics. METHODS: Cells from the AML-infiltrated skin from an M6 patient were infected with a lentivirus carrying OCT4, SOX2, KLF4 and C-MYC to induce iPSCs. The characteristics of the iPSCs were confirmed by alkaline phosphatase (ALP) staining. The proliferation ability of iPSCs was detected with a CCK-8 assay. The expression of pluripotency markers was measured by immunostaining, and the expression of stem cell-related genes was detected by qRT-PCR; distortion during the induction process was detected by karyotype analysis; the differentiation potential of iPSCs was determined by embryoid body-formation and teratoma-formation assays. ALP staining confirmed that these cells exhibited positive staining and had the characteristics of iPSCs. RESULTS: The CCK-8 assay showed that the iPSCs had the ability to proliferate. Immunostaining demonstrated that iPSC clones showed positive expression of NANOG, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. qRT-PCR results revealed that the mRNA expression of Nanog, Lin28, Cripto, FOX3, DNMT3b, DPPA2, and DPPA4 significantly increased in iPSCs. Karyotype analysis found no chromosome aberration in the iPSCs. The results of the embryoid body-formation and teratoma-formation assays indicated that the iPSCs had the potential to differentiate into all three germ layers. CONCLUSION: Our study provided evidence that an iPSC line derived from AML cells was successfully established.

Paenibacillus bovis sp. nov., isolated from raw yak (Bos grunniens) milk.

Strain BD3526T, isolated from raw yak milk collected in Tibet, China, was studied to determine its taxonomic status. The strain was Gram-reaction positive, motile, catalase-positive, aerobic or facultatively anaerobic. The DNA G+C content of the strain was 47.5 mol% and its peptidoglycan contained meso-diaminopimelic acid. The predominant menaquinone was MK-7. The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and C16 : 0. Based on 16S rRNA gene sequence analysis, similarities among strain BD3526T and its most closely related species, Paenibacillus shenyangensis A9T, 'Paenibacillus dauci' H9, 'Paenibacillus wulumuqiensis' Y24 and Paenibacillus hunanensis DSM 22170T were 99.0, 98.5, 97.3 and 96.7 %, respectively. Levels of DNA-DNA relatedness among strain BD3526T and P. hunanensis DSM 22170T and Paenibacillus polymyxa ATCC 842T ( = DSM 36T), the type species of the genus, were 41.2 and 45.6 %, respectively. In silico genome-to-genome comparison showed that the DNA-DNA hybridization values among strain BD3526T and P. shenyangensis A9T, 'P. dauci' H9 and 'P. wulumuqiensis' Y24 were lower than 70 %. Based on its molecular and physiological properties, strain BD3526T ( = DSM 28815T = CGMCC 8333T) is identified as the type strain of a novel species within the genus Paenibacillus, for which the name Paenibacillus bovis is proposed.

High Milk-Clotting Activity Expressed by the Newly Isolated Paenibacillus spp. Strain BD3526.

Paenibacillus spp. BD3526, a bacterium exhibiting a protein hydrolysis circle surrounded with an obvious precipitation zone on skim milk agar, was isolated from raw yak (Bos grunniens) milk collected in Tibet, China. Phylogenetic analysis based on 16S rRNA and whole genome sequence comparison indicated the isolate belong to the genus Paenibacillus. The strain BD3526 demonstrated strong ability to produce protease with milk clotting activity (MCA) in wheat bran broth. The protease with MCA was predominantly accumulated during the late-exponential phase of growth. The proteolytic activity (PA) of the BD3526 protease was 1.33-fold higher than that of the commercial R. miehei coagulant. A maximum MCA (6470 ± 281 SU mL(-1)) of the strain BD3526 was reached under optimal cultivation conditions. The protease with MCA was precipitated from the cultivated supernatant of wheat bran broth with ammonium sulfate and purified by anion-exchange chromatography. The molecular weight of the protease with MCA was determined as 35 kDa by sodium dodecyl sulfate-polyacrylamide gels electrophoresis (SDS-PAGE) and gelatin zymography. The cleavage site of the BD3526 protease with MCA in κ-casein was located at the Met106-Ala107 bond, as determined by mass spectrometry analysis.

Effect of acidification on the protection of alginate-encapsulated probiotic based on emulsification/internal gelation.

BACKGROUND: The method of emulsification/internal gelation is commonly used to prepare alginate microspheres for lactic acid bacteria (LAB). This paper focused on the influence of acidification parameters, i.e. acid/Ca molar ratio and acidification time, on the physical properties and cell protection efficiency of microspheres and their correlations. RESULTS: With increasing acid/Ca molar ratio and acidification time, the average diameter of microspheres decreased and their mechanical strength increased. Interestingly, wet alginate microspheres shrank in simulated gastric juice (SGJ) while they swelled in bile salts solution (BS). The shrinkage or swelling ratio decreased with increasing mechanical strength. Correlation analysis showed that the encapsulated cell survivals in both SGJ and BS were positively correlated with the mechanical strength of microspheres but negatively with the shrinkage or swelling ratio. BacLight LIVE/DEAD assay suggested that the viability of encapsulated cells in fresh, SGJ-treated and BS-treated microspheres was closely related to cell membrane integrity. CONCLUSION: Acidification is a key step during microsphere preparation, which strongly affected the physical properties of alginate microspheres, resulting in different cell protection efficiency. The resulting well-protected LAB can be applied in probiotics foods. © 2016 Society of Chemical Industry.

Levan-Producing Leuconostoc citreum Strain BD1707 and Its Growth in Tomato Juice Supplemented with Sucrose.

A levan-producing strain, BD1707, was isolated from Tibetan kefir and identified as Leuconostoc citreum. The effects of carbon sources on the growth of L. citreum BD1707 and levan production in tomato juice were measured. The changes in pH, viable cell count, sugar content, and levan yield in the cultured tomato juice supplemented with 15% (wt/vol) sucrose were also assayed. L. citreum BD1707 could synthesize more than 28 g/liter of levan in the tomato juice-sucrose medium when cultured at 30°C for 96 h. Based on the monosaccharide composition, molecular mass distribution, Fourier transform infrared (FTIR) spectra, and nuclear magnetic resonance (NMR) spectra, the levan synthesized by L. citreum BD1707 was composed of a linear backbone consisting of consecutive ß-(2→6) linked d-fructofuranosyl units, with an estimated average molecular mass of 4.3 × 10(6) Da.

An immune sandwich assay of carcinoembryonic antigen based on the joint use of upconversion phosphors and magnetic beads.

We herein report a sensitive and selective immunosensor for carcinoembryonic antigen (CEA) based on the joint use of upconversion phosphors (UCPs) and magnetic beads (MBs). UCPs as the signal probe were designed with a core-shell structure which provided a 40-fold enhancement of the luminescence intensity. Poly(acrylic acid) (PAA)-modified UCPs were covalently conjugated with the anti-CEA antibody (coating), and streptavidin functionalized magnetic beads were combined with another biotin-tagged anti-CEA antibody. With the assistance of a magnet, the as-formed immune sandwich in the presence of CEA can be readily separated from the assay matrix. The immunosensor showed a linear dynamic range for CEA within 0.05-20 ng mL(-1) in a buffered aqueous solution, and 0.1-20 ng mL(-1) in a human serum sample. The sensor was highly specific to CEA. Our results have suggested the potential application of the UCP-MB based immunoassay for CEA in clinical analysis.

Construction of an upconversion nanoprobe with few-atom silver nanoclusters as the energy acceptor.

Herein we report that few-atom silver nanoclusters (Ag NCs) can be effective energy acceptors for upconversion phosphors (UCPs). A luminescence resonance energy transfer (LRET) probe for biothiols was constructed by decorating UCPs with dithiol-stabilized Ag NCs. Owing to the unique properties of ultrasmall NCs, properties which bridge the gap between those of small molecules and those of nanoparticles, the use of approximately 1.9 nm Ag NCs as energy acceptors endows the probe with high energy-transfer efficiency, good biocompatibility, and flexibility. The UCP-Ag NC nanoprobe enables rapid and robust target assay in solutions. It was also uploaded into living cells and used to detect intracellular biothiol levels with high discrimination. Moreover, the probe shows transportability in vivo and can be used for tissue imaging. The facile growth of few-atom metal NCs on diverse templates may enable the development of various nanoprobes combining UCPs and metal NCs.