两个八仙花品种花色苷的提取、鉴定和理化稳定性

为优化八仙花花色苷提取条件，探究具有不同花色可调性的八仙花花色苷组分和理化稳定性差异，初步解释八仙花花色可调性存在差异的原因，该文以花色不可调的‘蒂亚娜(Tijana)’和花色可调的‘拉维布兰(Ravi Brent)’八仙花(Hydrangea macrophylla)为材料，通过L₉(3³)正交试验确定超声波法提取花色苷的最优条件，利用UPLC-Q-TOF-MS法进行花色苷组分的鉴定，分析离体条件下温度、光照、金属离子和糖类对八仙花花色苷理化稳定性的影响。结果表明：(1)花色苷提取的最优条件是‘蒂亚娜’和‘拉维布兰’的乙醇浓度分别为70%和80%,料液比均为1∶20,提取时间均为20 min。(2)二者的主要花色苷组分均为飞燕草素-3-O-葡萄糖苷。(3)八仙花花色苷在温度≤70℃暗处保存效果更好。(4)花色不可调的‘蒂亚娜’八仙花花色苷对光照、糖类和大多金属离子更稳定；只有花色可调的‘拉维布兰’八仙花花色苷加入中低浓度(10～30 mmol·L^-1)Al³⁺后由粉色变为蓝色且稳定性提高，而‘蒂亚...     

Microvesicles Derived from Human Wharton's Jelly Mesenchymal Stem Cells Promote Human Renal Cancer Cell Growth and Aggressiveness through Induction of Hepatocyte Growth Factor

In our previous study, microvesicles (MVs) released from human Wharton''s jelly mesenchymal stem cells (hWJ-MSCs) retard the growth of bladder cancer cells. We would like to know if MVs have a similar effect on human renal cell carcinoma (RCC). By use of cell culture and the BALB/c nu/nu mice xeno-graft model, the influence of MVs upon the growth and aggressiveness of RCC (786-0) was assessed. Cell counting kit-8 (CCK-8) assay, incidence of tumor, tumor size, Ki-67 or TUNEL staining was used to evaluate tumor cell growth in vitro or in vivo. Flow cytometry assay (in vitro) or examination of cyclin D1 expression (in vivo) was carried out to determine the alteration of cell cycle. The aggressiveness was analyzed by Wound Healing Assay (in vitro) or MMP-2 and MMP-9 expression (in vivo). AKT/p-AKT, ERK1/2/p-ERK1/2 or HGF/c-MET expression was detected by real-time PCR or western blot. Our data demonstrated that MVs promote the growth and aggressiveness of RCC both in vitro and in vivo. In addition, MVs facilitated the progression of cell cycle from G_0/1 to S. HGF expression in RCC was greatly induced by MVs, associated with activation of AKT and ERK1/2 signaling pathways. RNase pre-treatment abrogated all effects of MVs. In summary, induction of HGF synthesis via RNA transferred by MVs activating AKT and ERK1/2 signaling is one of crucial contributors to the pro-tumor effect.     

Mutations derived from horseshoe bat ACE2 orthologs enhance ACE2-Fc neutralization of SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein mediates infection of cells expressing angiotensin-converting enzyme 2 (ACE2). ACE2 is also the viral receptor of SARS-CoV (SARS-CoV-1), a related coronavirus that emerged in 2002–2003. Horseshoe bats (genus Rhinolophus) are presumed to be the original reservoir of both viruses, and a SARS-like coronavirus, RaTG13, closely related to SARS-CoV-2, has been identified in one horseshoe-bat species. Here we characterize the ability of the S-protein receptor-binding domains (RBDs) of SARS-CoV-1, SARS-CoV-2, pangolin coronavirus (PgCoV), RaTG13, and LyRa11, a bat virus similar to SARS-CoV-1, to bind a range of ACE2 orthologs. We observed that the PgCoV RBD bound human ACE2 at least as efficiently as the SARS-CoV-2 RBD, and that both RBDs bound pangolin ACE2 efficiently. We also observed a high level of variability in binding to closely related horseshoe-bat ACE2 orthologs consistent with the heterogeneity of their RBD-binding regions. However five consensus horseshoe-bat ACE2 residues enhanced ACE2 binding to the SARS-CoV-2 RBD and neutralization of SARS-CoV-2 pseudoviruses by an enzymatically inactive immunoadhesin form of human ACE2 (hACE2-NN-Fc). Two of these mutations impaired neutralization of SARS-CoV-1 pseudoviruses. An hACE2-NN-Fc variant bearing all five mutations neutralized both SARS-CoV-2 pseudovirus and infectious virus more efficiently than wild-type hACE2-NN-Fc. These data suggest that SARS-CoV-1 and -2 originate from distinct bat species, and identify a more potently neutralizing form of soluble ACE2.     

Improved pulse transit time estimation by system identification analysis of proximal and distal arterial waveforms

We investigated the system identification approach for potentially improved estimation of pulse transit time (PTT), a popular arterial stiffness marker. In this approach, proximal and distal arterial waveforms are measured and respectively regarded as the input and output of a system. Next, the system impulse response is identified from all samples of the measured input and output. Finally, the time delay of the impulse response is detected as the PTT estimate. Unlike conventional foot-to-foot detection techniques, this approach is designed to provide an artifact robust estimate of the true PTT in the absence of wave reflection. The approach is also applicable to arbitrary types of arterial waveforms. We specifically applied a parametric system identification technique to noninvasive impedance cardiography (ICG) and peripheral arterial blood pressure waveforms from 15 humans subjected to lower-body negative pressure. We assessed the technique through the correlation coefficient (r) between its 1/PTT estimates and measured diastolic pressure (DP) per subject and the root mean squared error (RMSE) of the DP predicted from these estimates and measured DP. The technique achieved average r and RMSE values of 0.81 ± 0.16 and 4.3 ± 1.3 mmHg. For comparison, the corresponding values were 0.59 ± 0.37 (P < 0.05) and 5.9 ± 2.5 (P < 0.01) mmHg for the conventional technique applied to the same waveforms and 0.28 ± 0.40 (P < 0.001) and 7.2 ± 1.8 (P < 0.001) mmHg for the conventional technique with the ECG waveform substituted for the ICG waveform. These results demonstrate, perhaps for the first time, that the system identification approach can indeed improve PTT estimation.     

Biology and Biochemistry of Plant Phospholipases

Phospholipases are a complex group of enzymes that hydrolyze phospholipids. The plant phospholipase family is composed of multiple members with varying positional specificity, and each type is represented by multiple isoforms distinguishable by their structural, catalytic, and physiological characteristics. A large number of phospholipase genes and gene families have been identified and the biochemical properties of several members have been characterized, revealing considerable molecular and catalytic diversity. Forward and reverse genetics has further revealed that phospholipases are widely involved in physiological processes including lipid metabolism, cell signaling, and responses to biotic and abiotic stresses. Such studies have highlighted the potential biotechnological value of phospholipases as targets for improving stress tolerance. The catalytic diversity of various phospholipase isoforms is also of increasing interest for industrial biocatalysis. This review focuses on recently acquired information on biochemical, molecular and functional aspects of plant phospholipases.     

Efficient expression of an alkaline pectate lyase gene from Bacillus subtilis and the characterization of the recombinant protein

The gene encoding a novel alkaline pectate lyase (Apel) from Bacillus subtilis was cloned and expressed in B. subtilis WB600. Apel contained an ORF of 1,260 bp, encoding a signal peptide of 21 amino acids and a mature protein of 399 amino acids with a calculated molecular mass of 45497.9 Da. The mature Apel was structurally related to the enzymes in the polysaccharide lyase family 1. After purification, the recombinant Apel had a specific activity of 445 U mg⁻¹. The enzyme was optimally active at 50°C and pH 9.     

The role of SDF-1-CXCR4/CXCR7 axis in the therapeutic effects of hypoxia-preconditioned mesenchymal stem cells for renal ischemia/reperfusion injury

In vitro hypoxic preconditioning (HP) of mesenchymal stem cells (MSCs) could ameliorate their viability and tissue repair capabilities after transplantation into the injured tissue through yet undefined mechanisms. There is also experimental evidence that HP enhances the expression of both stromal-derived factor-1 (SDF-1) receptors, CXCR4 and CXCR7, which are involved in migration and survival of MSCs in vitro, but little is known about their role in the in vivo therapeutic effectiveness of MSCs in renal ischemia/reperfusion (I/R) injury. Here, we evaluated the role of SDF-1-CXCR4/CXCR7 pathway in regulating chemotaxis, viability and paracrine actions of HP-MSCs in vitro and in vivo. Compared with normoxic preconditioning (NP), HP not only improved MSC chemotaxis and viability but also stimulated secretion of proangiogenic and mitogenic factors. Importantly, both CXCR4 and CXCR7 were required for the production of paracrine factors by HP-MSCs though the former was only responsible for chemotaxis while the latter was for viability. SDF-1α expression was upregulated in postischemic kidneys. After 24 h systemical administration following I/R, HP-MSCs but not NP-MSCs were selectively recruited to ischemic kidneys and this improved recruitment was abolished by neutralization of CXCR4, but not CXCR7. Furthermore, the increased recruitment of HP-MSCs was associated with enhanced functional recovery, accelerated mitogenic response, and reduced apoptotic cell death. In addition, neutralization of either CXCR4 or CXCR7 impaired the improved therapeutic potential of HP-MSCs. These results advance our knowledge about SDF-1-CXCR4/CXCR7 axis as an attractive target pathway for improving the beneficial effects of MSC-based therapies for renal I/R.