木聚糖酶生产菌Saccharothrix variisporea YJ的筛选、发酵条件及酶学性质研究

以Azo-xylan为底物,利用双层平板法从堆肥中筛选到可降解木聚糖的菌株,16S rRNA测序分析显示该菌株与糖丝菌属（Saccharothrix variisporea）的同源性最高（99.33%）,命名为S. variisporea YJ。研究发现以酵母提取物或(NH₄)₂SO₄作为氮源、甘蔗叶作为碳源、初始pH值 7.0、发酵温度40 ℃、发酵时间5 d时,发酵液中木聚糖酶的酶活性最高。酶学性质研究表明该木聚糖酶的最适反应温度及pH值分别为55 ℃和8.0,在55 ℃以下及pH值 4.0~10.0的范围内保持较高稳定性。Na⁺能有效提高木聚糖酶活性,Mg²⁺和Mn²⁺没有明显影响,Cu²⁺则严重抑制木聚糖酶活性。此外,发酵液还可以直接对天然底物玉米芯进行降解。     

The PDZ-GEF Gef26 regulates synapse development and function via FasII and Rap1 at the Drosophila neuromuscular junction

Guanine nucleotide exchange factors (GEFs) are essential for small G proteins to activate their downstream signaling pathways, which are involved in morphogenesis, cell adhesion, and migration. Mutants of Gef26, a PDZ-GEF (PDZ domain-containing guanine nucleotide exchange factor) in Drosophila, exhibit strong defects in wings, eyes, and the reproductive and nervous systems. However, the precise roles of Gef26 in development remain unclear. In the present study, we analyzed the role of Gef26 in synaptic development and function. We identified significant decreases in bouton number and branch length at larval neuromuscular junctions (NMJs) in Gef26 mutants, and these defects were fully rescued by restoring Gef26 expression, indicating that Gef26 plays an important role in NMJ morphogenesis. In addition to the observed defects in NMJ morphology, electrophysiological analyses revealed functional defects at NMJs, and locomotor deficiency appeared in Gef26 mutant larvae. Furthermore, Gef26 regulated NMJ morphogenesis by regulating the level of synaptic Fasciclin II (FasII), a well-studied cell adhesion molecule that functions in NMJ development and remodeling. Finally, our data demonstrate that Gef26-specific small G protein Rap1 worked downstream of Gef26 to regulate the level of FasII at NMJs, possibly through a βPS integrin-mediated signaling pathway. Taken together, our findings define a novel role of Gef26 in regulating NMJ development and function.     

Recent advances in TMEM16A: Structure,function, and disease

TMEM16A (also known as anoctamin 1, ANO1) is the molecular basis of the calcium-activated chloride channels, with ten transmembrane segments. Recently, atomic structures of the transmembrane domains of mouse TMEM16A (mTMEM16A) were determined by single-particle electron cryomicroscopy. This gives us a solid ground to discuss the electrophysiological properties and functions of TMEM16A. TMEM16A is reported to be dually regulated by Ca²⁺ and voltage. In addition, the dysfunction of TMEM16A has been found to be involved in many diseases including cystic fibrosis, various cancers, hypertension, and gastrointestinal motility disorders. TMEM16A is overexpressed in many cancers, including gastrointestinal stromal tumors, gastric cancer, head and neck squamous cell carcinoma (HNSCC), colon cancer, pancreatic ductal adenocarcinoma, and esophageal cancer. Furthermore, overexpression of TMEM16A is related to the occurrence, proliferation, and migration of tumor cells. To date, several studies have shown that many natural compounds and synthetic compounds have regulatory effects on TMEM16A. These small molecule compounds might be novel drugs for the treatment of diseases caused by TMEM16A dysfunction in the future. In addition, recent studies have shown that TMEM16A plays different roles in different diseases through different signal transduction pathways. This review discusses the topology, electrophysiological properties, modulators and functions of TMEM16A in mediates nociception, gastrointestinal dysfunction, hypertension, and cancer and focuses on multiple regulatory mechanisms regarding TMEM16A.     

Silencing of PTGS2 exerts promoting effects on angiogenesis endothelial progenitor cells in mice with ischemic stroke via repression of the NF-κB signaling pathway

The objective of the current study is to investigate the effect of PTGS2 on proliferation, migration, angiogenesis and apoptosis of endothelial progenitor cells (EPCs) in mice with ischemic stroke through the NF-κB signaling pathway. Middle cerebral artery occlusion (MCAO) model was established in mice. EPCs were identified, in which ectopic expression and depletion experiments were conducted. The mRNA and protein expression of related factors in tissues and cells were measured. Besides, proliferation, migration, angiogenesis, and apoptosis, as well as cell cycle distribution, of cells were determined. MCAO mice showed overexpression of interleukin-6 (IL-6), IL-17, and IL-23, and increased positive protein expression of PTGS2, as well as expression of PTGS2, nuclear factor-κB (NF-κB), tumor suppressor region 1 (TSP-1) and Bcl-2-associated X protein (Bax), but underexpression of vascular endothelial growth factor (VEGF), S-phase kinase associated protein 2 (Skp2), and B-cell lymphoma 2 (Bcl-2). Moreover, ectopic expression of tumor necrosis factor-α significantly elevated the expression of PTGS2, NF-κB, TSP-1, and Bax, as well as cell apoptosis and cell cycle arrest, but decreased the expression of VEGF, Skp2, and Bcl-2, as well as proliferation, migration and angiogenesis of EPCs, and the PTGS2-siRNA group showed an opposite trend. Taken together, we conclude that the specific knockdown of PTGS2 expression could repress the NF-κB signaling pathway, thereby inhibits apoptosis and promotes proliferation, migration and angiogenesis of EPCs, providing protective effect on mice with ischemic stroke.     

Inhibition of BAP31 expression inhibits cervical cancer progression by suppressing metastasis and inducing intrinsic and extrinsic apoptosis

Cervical cancer is reported as one of the most lethal types of cancer among female. However, extensive studies of the molecular mechanisms that regulate the progression of cervical cancer are still required. B-cell associated protein (BAP)-31 is a 28-kDa integral membrane protein in the endoplasmic reticulum (ER), playing essential role in modulating various physiological processes. The present study indicated that BAP31 was a novel gene associated with cervical cancer development. Here, we demonstrated that BAP31 was significantly increased in human cervical cancer specimens, which was positively correlated to histological grade of the cancer. BAP31 knockdown suppressed cell proliferation, clonogenic ability and metastasis-associated traits in vitro, as well as carcinogenesis and pulmonary metastasis in vivo. Further studies indicated that the expression levels of transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-2, MMP-9, Rho-associated protein kinase 1 (ROCK1), α-smooth muscle actin (α-SMA), Vimentin and N-cadherin were markedly reduced by BAP31 knockdown in cervical cancer cells. In addition, intrinsic and extrinsic apoptosis was significantly induced in BAP31 knockdown cells, as evidenced by the increased expression of cleaved Caspase-8/-9/-3 and poly (ADP-ribose) polymerases (PARP). Notably, suppressing the activities of Caspase-8/-9 and ?3 obviously diminished BAP31 silence-triggered apoptosis. Together, these findings highlighted an essential role for BAP31 in the modulation of tumorigenesis and metastatic potential of cervical cancer, and demonstrated a promising application of BAP31 in cancer prevention.     

Effects of myeloid sirtuin 1 deficiency on hypothalamic neurogranin in mice fed a high-fat diet

Hypothalamic inflammation has been known as a contributor to high-fat diet (HFD)-induced insulin resistance and obesity. Myeloid-specific sirtuin 1 (SIRT1) deletion aggravates insulin resistance and hypothalamic inflammation in HFD-fed mice. Neurogranin, a calmodulin-binding protein, is expressed in the hypothalamus. However, the effects of myeloid SIRT1 deletion on hypothalamic neurogranin has not been fully clarified. To investigate the effect of myeloid SIRT1 deletion on food intake and hypothalamic neurogranin expression, mice were fed a HFD for 20 weeks. Myeloid SIRT1 knockout (KO) mice exhibited higher food intake, weight gain, and lower expression of anorexigenic proopiomelanocortin in the arcuate nucleus than WT mice. In particular, KO mice had lower ventromedial hypothalamus (VMH)-specific neurogranin expression. However, SIRT1 deletion reduced HFD-induced hypothalamic neurogranin. Furthermore, hypothalamic phosphorylated AMPK and parvalbumin protein levels were also lower in HFD-fed KO mice than in HFD-fed WT mice. Thus, these findings suggest that myeloid SIRT1 deletion affects food intake through VMH-specific neurogranin-mediated AMPK signaling and hypothalamic inflammation in mice fed a HFD.     

The auxin influx carrier,OsAUX3, regulates rice root development and responses to aluminium stress

In rice, there are five members of the auxin carrier AUXIN1/LIKE AUX1 family; however, the biological functions of the other four members besides OsAUX1 remain unknown. Here, by using CRISPR/Cas9, we constructed two independent OsAUX3 knock‐down lines, osaux3‐1 and osaux3‐2, in wild‐type rice, Hwayoung (WT/HY) and Dongjin (WT/DJ). osaux3‐1 and osaux3‐2 have shorter primary roots (PRs), decreased lateral root (LR) density, and longer root hairs (RHs) compared with their WT. OsAUX3 expression in PRs, LRs, and RHs further supports that OsAUX3 plays a critical role in the regulation of root development. OsAUX3 locates at the plasma membrane and functions as an auxin influx carrier affecting acropetal auxin transport. OsAUX3 is up‐regulated in the root apex under aluminium (Al) stress, and osaux3‐2 is insensitive to Al treatments. Furthermore, 1‐naphthylacetic acid accented the sensitivity of WT/DJ and osaux3‐2 to respond to Al stress. Auxin concentrations, Al contents, and Al‐induced reactive oxygen species‐mediated damage in osaux3‐2 under Al stress are lower than in WT, indicating that OsAUX3 is involved in Al‐induced inhibition of root growth. This study uncovers a novel pathway alleviating Al‐induced oxidative damage by inhibition of acropetal auxin transport and provides a new option for engineering Al‐tolerant rice species.     

The Barnes Maze Task Reveals Specific Impairment of Spatial Learning Strategy in the Intrahippocampal Kainic Acid Model for Temporal Lobe Epilepsy

Neurochemical Research - Temporal lobe epilepsy (TLE) is an acquired form of focal epilepsy, in which patients not only suffer from unprovoked, devastating seizures, but also from severe...