Characterization of a Robust and pH-Stable Tannase from Mangrove-Derived Yeast Rhodosporidium diobovatum Q95.

Tannase plays a crucial role in many fields, such as the pharmaceutical industry, beverage processing, and brewing. Although many tannases derived from bacteria and fungi have been thoroughly studied, those with good pH stabilities are still less reported. In this work, a mangrove-derived yeast strain Rhodosporidium diobovatum Q95, capable of efficiently degrading tannin, was screened to induce tannase, which exhibited an activity of up to 26.4 U/mL after 48 h cultivation in the presence of 15 g/L tannic acid. The tannase coding gene TANRD was cloned and expressed in Yarrowia lipolytica. The activity of recombinant tannase (named TanRd) was as high as 27.3 U/mL. TanRd was purified by chromatography and analysed by SDS-PAGE, showing a molecular weight of 75.1 kDa. The specific activity of TanRd towards tannic acid was 676.4 U/mg. Its highest activity was obtained at 40 °C, with more than 70% of the activity observed at 25-60 °C. Furthermore, it possessed at least 60% of the activity in a broad pH range of 2.5-6.5. Notably, TanRd was excellently stable at a pH range from 3.0 to 8.0; over 65% of its maximum activity remained after incubation. Besides, the broad substrate specificity of TanRd to esters of gallic acid has attracted wide attention. In view of the above, tannase resources were developed from mangrove-derived yeasts for the first time in this study. This tannase can become a promising material in tannin biodegradation and gallic acid production.

Prevalence of the emerging novel Alongshan virus infection in sheep and cattle in Inner Mongolia, northeastern China.

BACKGROUND: Alongshan virus (ALSV) is a novel discovered segmented flavivirus associated with human febrile illness in northeastern China. Ixodes persulcatus is considered as a candidate vector of ALSV in the endemic regions. However, the role of domesticated animals in the circulation and transmission of ALSV have not been investigated. To evaluate the prevalence of ALSV infections in domesticated animals, viral RNA and viral specific antibodies were detected in sheep and cattle in Hulunbuir of northeastern Inner Mongolia. The findings contribute to the understanding of the ecology and transmission of ALSV among different natural hosts. METHODS: A total of 480 animal serum samples were collected in Hulunbuir of northeastern China in May, 2017. Viral specific antibodies were tested by indirect enzyme-linked immunosorbent assay (ELISA) with a purified E. coli recombinant capsid protein (VP2) of ALSV (strain H3) and further detected by viral neutralization test (VNT). RNA in serum samples were extracted and detected for ALSV sequence by quantitative real-time RT-PCR. ALSV RNA positive samples were used for virus isolation. RESULTS: ALSV-specific antibodies were detected in 9.2% (22/240) of examined sheep and 4.6% (11/240) of examined cattle by ELISA, while lower serological positivity with 4.2% (10/240) for sheep and 1.7% (4/240) for cattle was confirmed by VNT. In contrast, the prevalence of ALSV RNA was much higher, ranging from 26.3% (63/240) in sheep to 27.5% (66/240) in cattle. The partial S1 (NS5-like) and S3 (NS3-like) segments of ALSVs in sheep and cattle shared high identities of more than 98% to the human and tick isolates in the studied regions. CONCLUSIONS: These results suggest that the natural infection of ALSV can be found in sheep and cattle in the endemic regions.

Up-Regulation Thioredoxin Inhibits Advanced Glycation End Products-Induced Neurodegeneration.

BACKGROUND/AIMS: Diabetic retinopathy (DR) is one of the most serious complications of diabetes and is the leading cause of adult blindness in developed countries. Advanced glycation end products (AGEs) accumulation in diabetes is associated with its complications. Thioredoxin (Trx) is a small molecule (12kDa) antioxidant protein widely distributed in mammalian tissues, which has important biological functions including anti-apoptosis and transcriptional regulation. In a previous study, we found that Trx plays a key role in retinal neurodegeneration prior to the occurrence of endothelial damage in diabetic mice. In this study, our aim is to determine the effect of Trx on neurodegeneration induced by AGEs in order to identify new therapeutic targets for the clinical treatment and prevention of DR. METHODS: In vivo, a high-fat diet and Streptozotocin (STZ) injection were used to generate a mouse model of diabetes. Histology was utilized to examine tissue morphology and measure the outer nuclear layer (ONL) thickness. Electroretinography (ERG) was used to assess retinal function and Western blot was used to examine protein expression. In vitro, three methods of Trx up-regulation were used, including a stable cell line that overexpresses Trx, treatment with Sulforaphane, and shRNA down-regulation Txnip. Cells were treated with AGEs, and level of apoptosis was performed to quantify this by flow cytometry and TUNEL. Quantitative Reverse Transcription PCR (qRT-PCR), Western blotting and immunofluorescence were used to measure gene and protein expression. Transmission electron microscopy (TEM) was used to observe autophagosomes. RESULTS: We found that diabetic mice display decreased retinal function and reduced ONL thickness with AGEs accumulation and a reduction of Trx expression. Up-regulation Trx can prevent the ONL thickness decrease in diabetic mice, as observed by H&E staining. In vitro, up-regulation Trx resulted in decreased intracellular ROS generation, reduced apoptosis by inhibited autophagy. CONCLUSION: Up-regulating Trx inhibited neurodegeneration induced by AGEs. The underlying mechanism may be related to inhibit Txnip/mTOR pathway-mediated autophagy.

[Advances in targeted therapy for childhood acute myeloid leukemia].

At present, acute myeloid leukemia (AML) accounts for about 15%-20% of childhood acute leukemia. Although overall survival rate is increasing with the help of risk stratification, stratification of chemotherapy, and supportive treatment, conventional pharmacotherapy still has a limited clinical effect and certain limitations in improving remission rate in previously untreated patients and reducing recurrence after remission. With the development of precision medicine, the mechanisms of targeted therapy, including abnormal activation of AML-related signaling pathways and epigenetic modification, have been found in recent years. Molecular-targeted drugs can therefore act on specific receptors and target genes to improve clinical effect and the prognosis of AML patients.

Comparative study between original and traditional method in establishing a chronic sinus node damage model in rabbit.

Sick Sinus Syndrome is a common and refractory arrhythmia, needing further study in which setting up a credible sinus node damage model is important. To explore the feasibility and superiority of an original formaldehyde pinpoint pressing permeation (FPPP) method for building a chronic sinus node damage (CSND) model, 5 rabbits were chosen from 35 as a sham-operation group, and the remaining were randomly divided into two groups: the formaldehyde wet compressing (FWC) group, in which models were established by applying a cotton bud dipped in 20% formaldehyde onto the sinus node (SN) area, and the FPPP group, in which models were established by injecting formaldehyde into the SN area through a self-made pinpointing and injecting electrode. We found that in both groups, the HR at 2 h, 24 h, 1 wk, and 2 wk after modeling decreased compared with premodeling; sinoatrial conduction time, sinus node recovery time, and corrected sinus node recovery time were prolonged compared with premodeling. The indexes mentioned shortened by 2 wk after modeling compared with 2 h in the FWC group, whereas they were stable after modeling in the FPPP group. The modeling achievement ratio in the FPPP group was higher and the death rate was lower. Under light microscope, paraffin sections of the SN tissue and cells showed severe injury in both groups. The results indicate that the CSND models in rabbits can be successfully established by the FPPP method, with higher achievement ratio, lower death rate, better stabilization effect, and less damaging comparing with the traditional method.

[Effect of kangxin fulu recipe on electrophysiological functions of the sinoatrial node in rabbits with sick sinus syndrome].

OBJECTIVE: To study the effect of Kangxin Fulu Recipe (KFR) on electrophysiological functions of the sinoatrial node in rabbits with sick sinus syndrome (SSS). METHODS: Sixty big ears white rabbits were randomly divided into six groups, i.e., the normal group, the model group, the atropine group, the high dose KFR group, the middle dose KFR group, and the low dose KFR group, ten in each group. SSS model was established by injecting formaldehyde to the sinoatrial node except those in the normal group. Changes in AA interval, the sinoatrial conduction time (SACT), the sinus node recovery time (SNRT), and the corrected sinus node recovery time (CSNRT) were measured before and after modeling, seven days before and after gastrogavage. RESULTS: (1) The AA interval and SACT could be significantly shortened in the high dose KFR group, the middle-dose KFR group, and the atropine group (P<0.05, P<0.01). Better effects were obtained in the former two groups (P<0.05). (2) SNRT and CSNRT could be shortened in the high dose KFR group and the atropine group, with no statistical difference between the two groups (P>0.05). CONCLUSION: The electrophysiological mechanism of KFR might possibly be correlated with accelerating the recovery of sinus node autorhythmicity and conduction functions.

Differentiation of Wharton's jelly primitive stromal cells into insulin-producing cells in comparison with bone marrow mesenchymal stem cells.

Primitive stromal cells can be isolated from umbilical cord Wharton's jelly (UC-PSCs). Umbilical cord can be easily obtained without causing pain to donors, and the procedure avoids ethical and technical issues. UC-PSCs are more primitive than mesenchymal stem cells (MSCs) isolated from some other tissue sources. In this study, UC-PSCs were induced to differentiate into insulin-producing cells, and compared with bone marrow-derived MSCs (BM-MSCs) for their pancreatic differentiation potential. UC-PSCs showed significantly higher proliferation than BM-MSCs. During pancreatic induction, UC-PSCs formed larger islet-like cell clusters than BM-MSCs. Immunocytochemical analysis showed that higher expression of the pancreatic-specific transcription factor PDX-1 was detected in differentiated UC-PSCs than in differentiated BM-MSCs. Flow cytometry analysis demonstrated that the percentage of differentiated UC-PSCs expressing pancreatic-specific marker C-peptide was 72% higher than differentiated BM-MSCs. Radioimmunoassay revealed that differentiated UC-PSCs secreted significantly more insulin than differentiated BM-MSCs. These results demonstrated that UC-PSCs had higher pancreatic differentiation potential than BM-MSCs. Therefore, UC-PSCs are more suitable for pancreatic tissue engineering in the treatment of type I diabetes than BM-MSCs.