Over-expression of microRNA-494 up-regulates hypoxia-inducible factor-1 alpha expression via PI3K/Akt pathway and protects against hypoxia-induced apoptosis

Background

Hypoxia-inducible factor-1 alpha (HIF-1α) is one of the key regulators of hypoxia/ischemia. MicroRNA-494 (miR-494) had cardioprotective effects against ischemia/reperfusion (I/R)-induced injury, but its functional relationship with HIF-1α was unknown. This study was undertaken to determine if miR-494 was involved in the induction of HIF-1α.

Results

Quantitative RT-PCR showed that miR-494 was up-regulated to peak after 4 hours of hypoxia in human liver cell line L02. To investigate the role of miR-494, cells were transfected with miR-494 mimic or miR-negative control, followed by incubation under normoxia or hypoxia. Our results indicated that overexpression of miR-494 significantly induced the expression of p-Akt, HIF-1α and HO-1 determined by qRT-PCR and western blot under normoxia and hypoxia, compared to negative control (p < 0.05). While {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 treatment markedly abolished miR-494-inducing Akt activation, HIF-1α and HO-1 increase under both normoxic and hypoxic conditions (p < 0.05). Moreover, apoptosis detection using Annexin V indicated that overexpression of miR-494 significantly decreased hypoxia-induced apoptosis in L02 cells, compared to control (p < 0.05). MiR-494 overexpression also decreased caspase-3/7 activity by 1.27-fold under hypoxia in L02 cells.

Conclusions

Overexpression of miR-494 upregulated HIF-1α expression through activating PI3K/Akt pathway under both normoxia and hypoxia, and had protective effects against hypoxia-induced apoptosis in L02 cells. Thus, these findings suggested that miR-494 might be a target of therapy for hepatic hypoxia/ischemia injury.     

Serine O-acetyltransferase is important,but not essential for cysteine–methionine synthesis in Fusarium graminearum

O-acetyltransferase (SAT) is a key enzyme converting serine into O-acetylserine in the synthesis of sulphur-containing amino acids. To characterize the function of FgSAT in Fusarium graminearum, three deletion mutants of FgSAT (ΔFgSAT-1, -2 and -18) were obtained using a gene replacement strategy. The three mutants did not show recognizable phenotypic changes on potato dextrose agar medium, but exhibited a very weak growth on fructose gelatin agar (FGA) medium containing SO₄ ^2? as sole sulfur source. Supplementation of O-acetylserine, cysteine, or methionine, but not serine, rescued the defect of mycelial growth in FgSAT deletion mutants, indicating that FgSAT is involved in conversion of serine into O-acetylserine. The three mutants had a decrease in conidiation in mung bean liquid, but not in carboxymethyl cellulose. Virulence, deoxynivalenol production and fungicide sensitivity assays found that the three mutants showed no significant difference from wild-type progenitor PH-1. Real-time PCR assays detected an increase in expression levels of FgOAHS, FgCBS and FgCGL genes involved in the alternative pathway in FgSAT deletion mutants, suggesting that the alternative pathway in F. graminearum is present and can operate. Addition of homoserine, the upstream substrate of the alternative pathway, also restored the normal mycelial growth of FgSAT deletion mutants on FGA, indicating that the alternative pathway in F. graminearum might be positively regulated by homoserine.     

现代生物技术在乳品工业中的应用研究

随着细胞生物学和分子生物学的发展及对生物物理、生物化学、遗传学和免疫学研究的深入,培育了基因工程、细胞工程、酶工程、发酵工程等改变生物特性进行物质转化的现代生物技术,形成了DNA探针、PCR技术、分子标记、生物荧光技术、基因芯片技术等前沿性的生物检测技术,其在乳品工业中的广泛应用,推动了乳业的技术变革,对乳品生产、研究和乳品安全意义重大。     

Identification of two antagonists of the scavenger receptor CD36 using a high-throughput screening model

CD36, a class B scavenger receptor, is an integral membrane protein that mediates the endocytosis of modified lipoproteins. The functions of CD36 are complex and have been associated with atherosclerosis. In the current study, we developed a high-throughput screening (HTS) assay to identify small molecule antagonists by expressing human CD36 using a Bac-to-Bac baculovirus expression system in Spodoptera frugiperda (Sf9) cells. Uptake of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate-labeled acetylated low-density lipoprotein (DiI-AcLDL) revealed that the IC₅₀ values for the CD36 ligands oxidatively modified LDL (Ox-LDL), Ac-LDL, and high-density lipoprotein (HDL) were 0.039, 0.019, and 0.010 μg/ml, respectively. Using the HTS assay, two novel compounds, 2016481B and 2038751B, were found to inhibit DiI-AcLDL uptake in insect cells and exhibited IC₅₀ values of 17.4 and 23.7 μM, respectively. These two novel compounds also inhibited DiI-AcLDL uptake in cultured Chinese hamster ovary (CHO) cells permanently expressing human CD36. Furthermore, these two compounds inhibited lipid accumulation in RAW 264.7 murine macrophage cells in foam cell assays. This HTS assay represents a potential method for identifying more effective macrophage scavenger receptor antagonists, which may serve as starting points for the development of novel anti-atherosclerotic agents.     

Contribution of inoculation with azolla combined with nitrogen,phosphorus and zinc to rice in Nile Delta

Rice performance, in terms of plant height, productive tillering, yield and N-contents of grain and straw, harvest index (grain yield as a percentage of grain plus straw yields) and relative fertilizer N-use efficiency (kg grain yield/kg fertilizer-N) was enhanced by urea, ZnSO₄ and green manuring withAzolla caroliniana. Unlike urea fertilizer, calcium superphosphate increased the rate of azolla field colonization and promoted a thick, healthy dark-green mat of the fern. Response to ZnSO₄ was higher in the azolla-free sub-subplots. Application of ZnSO₄ corrected symptoms of Zn deficiency in rice but the addition of calcium superphosphate in the absence of Zn intensified the symptoms of Zn deficiency.     

Nucleolar delocalization of human topoisomerase I in response to topotecan correlates with sumoylation of the protein.

DNA topoisomerase (topo) I is an essential nuclear protein and a target for anticancer drug camptothecin derivatives. As a nuclear protein, topo I is concentrated in the nucleolus. However, this nucleolar distribution of topo I is dynamic. It has been shown recently that topo I rapidly moves out of the nucleolus (nucleolar delocalization) in response to topo I inhibitors. In the present study, we demonstrated that nucleolar delocalization of topo I is associated with its conjugation by SUMOs (small ubiquitin-like modifiers) in response to the topo I inhibitor topotecan. Time-course experiments revealed that SUMO-topo I conjugation occurred at as early as 5 min after drug treatment, which was earlier than its observed nucleolar delocalization. Furthermore, heat shock blocked sumoylation of topo I; it also blocked the nucleolar delocalization of topo I fusion proteins. UBC9 is an E2 (ubiquitin carrier protein)-conjugating enzyme essential for sumoylation. Although overexpression of wild-type UBC9 enhanced both sumoylation and nuclear delocalization of topo I, overexpression of a UBC9 dominant negative mutant attenuated topo I sumoylation and its nucleolar delocalization. Taken together, our results suggest that sumoylation of topo I might serve as an addressing tag for its nucleolar delocalization in response to topo I inhibitors.     

Urinary Retention,Incontinence, and Dysregulation of Muscarinic Receptors in Male Mice Lacking Mras

Here we show that male, but not female mice lacking expression of the GTPase M-Ras developed urinary retention with distention of the bladder that exacerbated with age but occurred in the absence of obvious anatomical outlet obstruction. There were changes in detrusor morphology in Mras ^-/- males: Smooth muscle tissue, which exhibited a compact organization in WT mice, appeared disorganized and became increasingly ‘layered’ with age in Mras ^-/- males, but was not fibrotic. Bladder tissue near the apex of bladders of Mras ^-/- males exhibited hypercontractility in response to the cholinergic agonist carbachol in in vitro, while responses in Mras ^-/- females were normal. In addition, spontaneous phasic contractions of detrusors from Mras ^-/- males were increased, and Mras ^-/- males exhibited urinary incontinence. We found that expression of the muscarinic M2 and M3 receptors that mediate the cholinergic contractile stimuli of the detrusor muscle was dysregulated in both Mras ^-/- males and females, although only males exhibited a urinary phenotype. Elevated expression of M2R in young males lacking M-Ras and failure to upregulate M3R with age resulted in significantly lower ratios of M3R/M2R expression that correlated with the bladder abnormalities. Our data suggests that M-Ras and M3R are functionally linked and that M-Ras is an important regulator of male bladder control in mice. Our observations also support the notion that bladder control is sexually dimorphic and is regulated through mechanisms that are largely independent of acetylcholine signaling in female mice.     

红外相机技术在鼠类密度估算中的应用

2009年5月至2011年7月,在古田山国家自然保护区24 hm2(600 m×400 m)样地中用分层随机抽样法布置20台红外相机,监测样地内的鼠类密度.利用红外相机技术,引用物理学中气体分子碰撞率原理,在不对鼠类进行个体识别的情况下,估算样地内鼠类密度.结果表明,以此估算的样地内鼠类密度D3与标志重捕法估算的鼠类密度D之间不存在显著差异(P＞0.05),两者契合程度高,说明此模型具有相当高的精确性.而在较高的相机分布密度(0.83台/hm2)下得出的鼠类密度季节消长状况也验证了该模型的可靠程度.     

A super pan-genomic landscape of rice

Pan-genomes from large natural populations can capture genetic diversity and reveal genomic complexity. Using de novo long-read assembly, we generated a graph-based super pan-genome of rice consisting of a 251-accession panel comprising both cultivated and wild species of Asian and African rice. Our pan-genome reveals extensive structural variations (SVs) and gene presence/absence variations. Additionally, our pan-genome enables the accurate identification of nucleotide-binding leucine-rich repeat genes and characterization of their inter- and intraspecific diversity. Moreover, we uncovered grain weight-associated SVs which specify traits by affecting the expression of their nearby genes. We characterized genetic variants associated with submergence tolerance, seed shattering and plant architecture and found independent selection for a common set of genes that drove adaptation and domestication in Asian and African rice. This super pan-genome facilitates pinpointing of lineage-specific haplotypes for trait-associated genes and provides insights into the evolutionary events that have shaped the genomic architecture of various rice species.Subject terms: Structural variation, Comparative genomics