表面活性剂对嗜盐嗜碱硫碱弧菌D301生成及利用硫颗粒的影响

【背景】微生物脱硫是脱除气体中硫化氢的一种有效方法,其中,硫颗粒的生成与代谢是控制生物脱硫效率的关键,但目前相应的控制方法很少。【目的】研究不同种类表面活性剂对硫碱弧菌D301生成及利用硫颗粒的影响。【方法】通过摇床培养,利用X射线衍射、冷场发射扫描电镜、能谱分析及傅里叶红外光谱对硫颗粒进行表征。【结果】单质硫主要以S8形式存在,吐温-80和十二烷基磺酸钠(Sodium Dodecyl Sulfate,SDS)的添加对硫颗粒的形态及生成量影响明显。对照组中生成的硫颗粒呈规则球形,光滑完整,其表面附着蛋白质等生物大分子;加入0.01 g/L吐温-80后,硫颗粒呈长杆状、颗粒增大、利用速率减慢;加入0.3g/L的SDS后,硫颗粒呈短棒状、生成量减少、利用速率加快,同时延缓了硫碱弧菌D301的衰亡。【结论】添加表面活性剂可以改变硫颗粒形态并且影响其利用,是一种调控硫颗粒生成和代谢的有效手段。     

DAZL regulates proliferation of human primordial germ cells by direct binding to precursor miRNAs and enhances DICER processing activity

Understanding the molecular and cellular mechanisms of human primordial germ cells (hPGCs) is essential in studying infertility and germ cell tumorigenesis. Many RNA-binding proteins (RBPs) and non-coding RNAs are specifically expressed and functional during hPGC developments. However, the roles and regulatory mechanisms of these RBPs and non-coding RNAs, such as microRNAs (miRNAs), in hPGCs remain elusive. In this study, we reported a new regulatory function of DAZL, a germ cell-specific RBP, in miRNA biogenesis and cell proliferation. First, DAZL co-localized with miRNA let-7a in human PGCs and up-regulated the levels of >100 mature miRNAs, including eight out of nine let-7 family, miR21, miR22, miR125, miR10 and miR199. Purified DAZL directly bound to the loops of precursor miRNAs with sequence specificity of GUU. The binding of DAZL to the precursor miRNA increased the maturation of miRNA by enhancing the cleavage activity of DICER. Furthermore, cell proliferation assay and cell cycle analysis confirmed that DAZL inhibited the proliferation of in vitro PGCs by promoting the maturation of these miRNAs. Evidently, the mature miRNAs up-regulated by DAZL silenced cell proliferation regulators including TRIM71. Moreover, DAZL inhibited germline tumor cell proliferation and teratoma formation. These results demonstrate that DAZL regulates hPGC proliferation by enhancing miRNA processing.     

The role of the Wnt signalling pathway in the energy metabolism of bone remodelling

ObjectivesBone remodelling is necessary to repair old and impaired bone caused by aging and its effects. Injury in the process of bone remodelling generally leads to the development of various bone diseases. Energy metabolism plays crucial roles in bone cell formation and function, the disorder of which will disrupt the balance between bone formation and bone resorption.Materials and MethodsHere, we review the intrinsic interactions between bone remodelling and energy metabolism and the role of the Wnt signalling pathway.ResultsWe found a close interplay between metabolic pathways and bone homeostasis, demonstrating that bone plays an important role in the regulation of energy balance. We also discovered that Wnt signalling is associated with multiple biological processes regulating energy metabolism in bone cells.ConclusionsThus, targeted regulation of Wnt signalling and the recovery of the energy metabolism function of bone cells are key means for the treatment of metabolic bone diseases.

As a critical physiological process, bone remodelling is necessary to repair impaired bone caused by daily physical load and to prevent the effects of ageing. The homeostasis of bone remodelling largely depends on the balance of energy metabolism, such as glucose, glutamine, and fatty acid metabolism, and the disturbance of which will disrupt the balance between bone formation and bone resorption. Wnt signalling pathway including critical Wnt molecules (Wnt3a, Wnt7b, Wnt10b) is significant in these life processes, which links the intrinsic interactions between bone remodelling and energy metabolism, making it a promising target for the treatment of metabolic bone diseases.     

Plant biomechanics and resilience to environmental changes are controlled by specific lignin chemistries in each vascular cell type and morphotype

The biopolymer lignin is deposited in the cell walls of vascular cells and is essential for long-distance water conduction and structural support in plants. Different vascular cell types contain distinct and conserved lignin chemistries, each with specific aromatic and aliphatic substitutions. Yet, the biological role of this conserved and specific lignin chemistry in each cell type remains unclear. Here, we investigated the roles of this lignin biochemical specificity for cellular functions by producing single cell analyses for three cell morphotypes of tracheary elements, which all allow sap conduction but differ in their morphology. We determined that specific lignin chemistries accumulate in each cell type. Moreover, lignin accumulated dynamically, increasing in quantity and changing in composition, to alter the cell wall biomechanics during cell maturation. For similar aromatic substitutions, residues with alcohol aliphatic functions increased stiffness whereas aldehydes increased flexibility of the cell wall. Modifying this lignin biochemical specificity and the sequence of its formation impaired the cell wall biomechanics of each morphotype and consequently hindered sap conduction and drought recovery. Together, our results demonstrate that each sap-conducting vascular cell type distinctly controls their lignin biochemistry to adjust their biomechanics and hydraulic properties to face developmental and environmental constraints.

During the development of each vascular cell, specific lignin chemistries control their biomechanics and water conduction properties to face environmental changes.

IN A NUTSHELL Background: Lignin comprises multiple cell wall–localized aromatic polymers that are essential for vascular plants to conduct water and strengthen their organs. It has long been thought that lignin was randomly and nonspecifically assembled to provide mechanical strengthening and waterproofing to cells by filling-up the empty spaces in the cell walls. However, the different cell types and morphotypes forming the different sap-conducting pipes and their cell wall layers (inner vs. outer layer) exhibit specific lignin chemistries that are conserved among plant species. We, therefore, investigated the function of these specific lignin chemistries at the cell and cell wall layer levels for the different sap-conducting pipes in plants. Question: What is the function of a specific lignin chemistry for the different plant sap-conducting pipe cells? Can changes in the lignin chemistry of sap-conducting cells affect their hydraulic capacity when facing environmental conditions such as drought? Findings: We answered these questions by changing lignin levels and composition, using drugs to block lignin formation, and/or genetic engineering to switch off genes, in three complementary systems: (1) isolated cells grown in test tubes that we can trigger to become sap conduits, (2) annual plants, and (3) hardwood trees. We show that lignin chemistry is specific to each cell morphotype and changes during cell maturation, modifying the amount of lignin, the chemical composition of lignin units, and the position of these units in the longer polymer. These specific lignin chemistries are required for the proper function of each cell morphotype to properly conduct the sap and strengthen plant organs. Modifying the amount, the composition, and the time when specific units with distinct chemistry are incorporated in lignin of each cell morphotype has dramatic effects, causing defects in sap conduit hydraulic and biomechanical properties. The ratio between the different chemical units of lignin needs to be fine-tuned to adjust plant sap conduction and mechanical strengthening. Thus, changes in the proportion of lignin units with distinct chemistries confer different hydraulic and mechanical properties enabling plants to better resist and/or recover from drought. We also revealed that increases in the proportion of lignin units with aldehyde modulate plant pipe hydraulic and mechanical properties. Next steps: We are now working to identify and understand the molecular mechanisms that control the formation of specific lignin chemistries in distinct sites and times during the development of the different cell wall layers in each cell type and morphotype.     

Thioredoxin 1 supports colorectal cancer cell survival and promotes migration and invasion under glucose deprivation through interaction with G6PD

Overcoming energy stress is a critical step for cells in solid tumors. Under this stress microenvironment, cancer cells significantly alter their energy metabolism to maintain cell survival and even metastasis. Our previous studies have shown that thioredoxin-1 (Trx-1) expression is increased in colorectal cancer (CRC) and promotes cell proliferation. However, the exact role and mechanism of how Trx-1 is involved in energy stress are still unknown. Here, we observed that glucose deprivation of CRC cells led to cell death and promoted the migration and invasion, accompanied by upregulation of Trx-1. Increased Trx-1 supported CRC cell survival under glucose deprivation. Whereas knockdown of Trx-1 sensitized CRC cells to glucose deprivation-induced cell death and reversed glucose deprivation-induced migration, invasion, and epithelial-mesenchymal transition (EMT). Furthermore, we identified glucose-6-phosphate dehydrogenase (G6PD) interacting with Trx-1 by HuPortTM human protein chip, co-IP and co-localization. Trx-1 promoted G6PD protein expression and activity under glucose deprivation, thereby increasing nicotinamide adenine dinucleotide phosphate (NADPH) generation. Moreover, G6PD knockdown sensitized CRC cells to glucose deprivation-induced cell death and suppressed glucose deprivation-induced migration, invasion, and EMT. Inhibition of Trx-1 and G6PD, together with inhibition of glycolysis using 2-deoxy-D-glucose (2DG), resulted in significant anti-tumor effects in CRC xenografts in vivo. These findings demonstrate a novel mechanism and may represent a new effective therapeutic regimen for CRC.     

Phosphorus Regulates the Level of Signaling Molecules in Rice to Reduce Cadmium Toxicity

Phosphorus treatment can reduce Cd accumulation and Cd toxicity in rice, but alterations in the internal regulatory network of rice during this process have rarely been reported. We have removed the effect of cadmium phosphate precipitation from the hydroponic system, treated a pair of different Cd-response rice varieties with different levels of phosphorus and cadmium and examined the changes in physiological indicators and regulatory networks. The results demonstrated that phosphorus treatment significantly reduced Cd accumulation in both types of rice, although the antioxidant systems within the two types of rice produced opposite responses. Overall, 3 mM phosphorus treatment to Cd-N decreased the expression of OsIAA17 and OsACO1 by 32% and 37%, respectively, while increasing the expression of OsNR2 by 83%; these three genes regulate the synthesis of auxin, ethylene, and nitric oxide in rice. IAA and NO levels in rice shoots increased by 24% and 96%, respectively, and these changes contribute to Cd detoxification. The cadmium transporter genes OsHMA2, OsIRT1, and OsABCC1 were significantly down-regulated in Cd-N roots after triple phosphorus treatment. These data suggest that phosphorus treatment can reduce Cd accumulation and enhance Cd resistance in rice by affecting the expression of signaling molecules.