Macromolecular synthesis in organ cultures of neonatal rat lung

Organ cultures of newborn rat lungs synthesize and accumulate DNA, RNA, collagen and noncollagenous proteins almost at a linear rate for at least 5 days. During this period the synthesis of collagen consistently exceeds the synthesis of noncollagenous proteins in a pattern similar to neonatal lung growth in vivo. Although some morphological characteristics of lung architecture are distorted after culture, fundamental structural similarities to lungs growing in intact animals are retained. When these cultures are maintained in atmospheres rich in oxygen, increased collagen synthesis is observed, a response similar to that of lungs in intact animals exposed to high oxygen concentrations in vivo. Our studies suggest that lung organ cultures may be a suitable system for investigating the biochemical aspects of lung tissue-environmental interaction. These studies were supported in parts by NIH Grant HL-19668, a contract (68-03-2005) from the U.S. Environmental Protection Agency, and grants from the California Lung Association.     

Pollination biology of two species ofKielmeyera (Guttiferae) from Brazilian cerrado vegetation

The pollination biology and breeding systems ofKielmeyera coriacea andK. speciosa, two sympatric woody species common in the cerrado vegetation of C. Brazil, were studied. Both species have similar nectarless, polystemonous Papaver-type flowers which are visited by a similar spectrum of insects, though they bloom in different seasons and are thus phenologically isolated. Large carpenter bees seem to be the most important pollinators and these and other bees effect buzz pollen retrieval despite the fact that anthers are not poricidal. Both species ofKielmeyera possess strong xenogamous breeding systems. The presence of staminate flowers and andromonoecy inK. coriacea, as well as the longevity ofK. speciosa flowers are discussed as alternative strategies to improve pollination success and reproductive efficacy.     

The CD95 (Fas/APO-1) receptor is phosphorylatedin vitro andin vivo and constitutively associates with several cellular proteins

Different CD95 (Fas/APO-1) isoforms and phosphory lated CD95 species were identified in human T and B cell lines. We had shown previously that the CD95 intracellular domain (IC), expressed as a glutathione S-transferase (GST) fusion protein in murine L929 fibroblasts, was phosphorylatedin vivo. GST-CD95IC was phosphorylatedin vitro by a kinase present in extracts from the human lymphocytic cell lines Jurkat and MP-1 and from murine L929 cells. Phosphoamino acid analysis indicated that phosphorylation occurred at multiple threonine residues and also at tyrosine (Tyr232 and Tyr291) and serine. Amino acids 191 to 275 of CD95 were sufficient for phosphorylation at threonine, tyrosine and serine and also mediated interaction with a 35 kDa cellular protein. Immuno-precipitation of CD95 and chemical cross-linking revealed CD95-associated proteins of approximately 35, 45 and 75 kDa. GST-CD95IC affinity chromatography detected binding of the 35 and 75 kDa protein species. The 75 kDa species may correspond to the CD95-associated proteins RIP or FAF1 and the 35 kDa protein may represent a TRADD analogue. These data indicate that several cellular proteins interact with CD95, possibly in a multi-protein complex, and that a kinase activity is associated with CD95 not onlyin vitro but alsoin vivo. Therefore, receptor phosphorylation may play a role in CD95 signal transduction. This work was in part supported by a grant from the Health Research Council of New Zealand (to JW).     

Synapse maturation and structural plasticity at Drosophila neuromuscular junctions

The Drosophila larval neuromuscular junction has recently emerged as a powerful model system to characterize the cellular and molecular events involved in the formation and flexibility of synapses. The combination of molecular, genetic, electrophysiological and anatomical approaches has revealed, for example, the functional significance of the discs-large gene product (a novel synapse-organizing protein) in the nervous system. This protein is involved in the clustering of at least one ion channel and in the structural modification of glutamatergic synapses during target muscle growth. The manipulation of the genes encoding ion channels, components of second-messenger cascades, and cell adhesion molecules is beginning to tease apart the mechanisms underlying structural synaptic plasticity.     

PDZ/PDZ interaction between PSD‐95 and nNOS neuronal proteins

N‐Methyl‐D‐aspartate (NMDA) receptors are key components in synaptic communication and are highly relevant in central nervous disorders, where they trigger excessive calcium entry into the neuronal cells causing harmful overproduction of nitric oxide by the neuronal nitric oxide synthase (nNOS) protein. Remarkably, NMDA receptor activation is aided by a second protein, postsynaptic density of 95 kDa (PSD95), forming the ternary protein complex NMDA/PSD95/nNOS. To minimize the potential side effects derived from blocking this ternary complex or either of its protein components, a promising approach points to the disruption of the PSD‐95/nNOS interaction which is mediated by a PDZ/PDZ domain complex. Since the rational development of molecules targeting such protein‐protein interaction relies on energetic and structural information herein, we include a thermodynamic and structural analysis of the PSD95‐PDZ2/nNOS‐PDZ. Two energetically relevant events are structurally linked to a “two‐faced” or two areas of recognition between both domains. First, the assembly of a four‐stranded antiparallel β‐sheet between the β hairpins of nNOS and of PSD95‐PDZ2, mainly enthalpic in nature, contributes 80% to the affinity. Second, binding is entropically reinforced by the hydrophobic interaction between side chains of the same nNOS β‐hairpin with the side chains of α2‐helix at the binding site of PSD95‐PDZ2, contributing the remaining 20% of the total affinity. These results suggest strategies for the future rational design of molecules able to disrupt this complex and constitute the first exhaustive thermodynamic analysis of a PDZ/PDZ interaction.     

miRNA-95靶向FOXD1基因对结直肠癌LoVo细胞放射敏感性的影响及其机制*

目的: 探讨miRNA-95靶向FOXD1基因对结直肠癌loVo细胞放射敏感性的影响及其机制。方法: 结直肠癌LoVo细胞购自武汉普诺赛生命科技有限公司,将LoVo细胞分为三组接种于6孔板中,每组3个复孔,实验重复3次,C组(对照组正常LoVo细胞),M组(miRNA-95-mimics转染LoVo细胞),I组(miRNA-95-inhibitions转染LoVo细胞),利用直线加速器6 MV/8 Gy的X射线垂直照射细胞,剂量率3 Gy/min,持续照射12 h后收集细胞。采用RT-PCR法检测LoVo细胞中FOXD1的表达情况,流式细胞术检测LoVo细胞凋亡情况,Western blot检测细胞中FOXD1蛋白的水平,细胞克隆测定细胞存活率,裸鼠成瘤实验取转染未经X射线照射的C组、M组、I组LoVo细胞细胞悬液,各取0.2 ml分别接种于C组、M组、I组BALB/C-nu雄性裸鼠左下肢足部皮上1次,每组10只,注射2周后,各组选取5只裸鼠进行X射线照射,每天4 Gy 照射一次,连续照射15 d,其余小鼠不照射,处死裸鼠并取出肿瘤进行称重。结果: 与C组比对,M组FOXD1水平明显升高,I组FOXD1水平明显低于M组、C组(P＜0.05);在同样8 Gy 照射后,与I组比对,C组和M组loVo细胞凋亡率显著下降(P＜0.05);在8 Gy照射后,与I组比对,M组和C组loVo细胞单克隆存活率有上升趋势(P＜0.05)。无照射条件下,与M组相比,C组和I组肿瘤体积减少(P均＜0.05),与C组比较,I组肿瘤体积减少(P＜0.05)。X射线照射15 d后,与无照射组各组裸鼠相比肿瘤体积显著减小(P均＜0.05),与M组相比,C组和I组肿瘤体积减少(P＜0.05)。结论: miRNA-95低表达可提高LoVo细胞的放射敏感性,促进细胞凋亡,其作用机制可能抑制FOXD1蛋白的活性有关。     

樟子松人工林营建对土壤颗粒组成变化的影响

植被恢复是退化生态系统的主要恢复措施,也是人类改善区域生态环境较为重要和直接的活动。目前,针对不同植被恢复方式对干旱半干旱地区土壤理化性质及生物特征开展了大量研究。然而,关于科尔沁沙地樟子松人工林营建对土壤颗粒组成变化的影响却鲜有报道。因此,以辽宁省章古台地区不同生长阶段(包括幼龄林、中龄林、成熟林和过熟林)的20块樟子松人工林样地为研究对象(以临近的7块天然草地为对照),研究了沙地樟子松人工林营建对0—100 cm土层土壤颗粒组成变化的影响。结果表明:沙质草地营建樟子松人工林后,不同土层土壤细颗粒(0.05 mm)含量均呈增加趋势,并且在0—10 cm层增加趋势明显,随土层深度增加土壤细颗粒增加量逐渐降低(除幼龄林外),但樟子松林地土壤颗粒组成仍以砂粒为主,土壤粘粒和粉粒含量极低(仅占5%左右)。随着樟子松人工林林龄的增加,土壤细颗粒变化量在0—10 cm层逐渐升高,而在10—100 cm层并无显著变化趋势。土壤细颗粒含量的变化在10—100 cm层与土壤含水量呈显著正相关,在0—10、20—40 cm和80—100 cm层与土壤全钾极显著负相关,在20—60 cm层与土壤有机碳呈显著正相关,在10—40 cm和80—100 cm层分别与土壤全磷呈显著正相关和负相关。综上所述,樟子松人工林营建可有效提高土壤细颗粒含量且在土壤表层效果明显,但短期内并不会使土壤颗粒组成发生显著变化,樟子松林改善土壤颗粒组成的同时也会使其他土壤因子发生相应的变化。     

Formation and function of phosphatidylserine and phosphatidylethanolamine in mammalian cells

Phosphatidylserine (PS) and phosphatidylethanolamine (PE) are metabolically related membrane aminophospholipids. In mammalian cells, PS is required for targeting and function of several intracellular signaling proteins. Moreover, PS is asymmetrically distributed in the plasma membrane. Although PS is highly enriched in the cytoplasmic leaflet of plasma membranes, PS exposure on the cell surface initiates blood clotting and removal of apoptotic cells. PS is synthesized in mammalian cells by two distinct PS synthases that exchange serine for choline or ethanolamine in phosphatidylcholine (PC) or PE, respectively. Targeted disruption of each PS synthase individually in mice demonstrated that neither enzyme is required for viability whereas elimination of both synthases was embryonic lethal. Thus, mammalian cells require a threshold amount of PS. PE is synthesized in mammalian cells by four different pathways, the quantitatively most important of which are the CDP-ethanolamine pathway that produces PE in the ER, and PS decarboxylation that occurs in mitochondria. PS is made in ER membranes and is imported into mitochondria for decarboxylation to PE via a domain of the ER [mitochondria-associated membranes (MAM)] that transiently associates with mitochondria. Elimination of PS decarboxylase in mice caused mitochondrial defects and embryonic lethality. Global elimination of the CDP-ethanolamine pathway was also incompatible with mouse survival. Thus, PE made by each of these pathways has independent and necessary functions. In mammals PE is a substrate for methylation to PC in the liver, a substrate for anandamide synthesis, and supplies ethanolamine for glycosylphosphatidylinositol anchors of cell-surface signaling proteins. Thus, PS and PE participate in many previously unanticipated facets of mammalian cell biology. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.     

microRNA-95 knockdown inhibits epithelial–mesenchymal transition and cancer stem cell phenotype in gastric cancer cells through MAPK pathway by upregulating DUSP5

This study investigated the role of microRNA-95 (miR-95) in gastric cancer (GC) and to elucidate the underlying mechanism. Initially, bioinformatic prediction was used to predict the differentially expressed genes and related miRNAs in GC. miR-95 and DUSP5 expression was altered in GC cell line (MGC803) to evaluate their respective effects on the epithelial–mesenchymal transition (EMT) process, cellular processes (cell proliferation, migration, invasion, cell cycle, and apoptosis), cancer stem cell (CSC) phenotype, as well as tumor growth ability. It was further predicted in bioinformatic prediction and verified in GC tissue and cell line experiments that miR-95 was highly expressed in GC. miR-95 negatively regulated DUSP5, which resulted in the MAPK pathway activation. Inhibited miR-95 or overexpressed DUSP5 was observed to inhibit the levels of CSC markers (CD133, CD44, ALDH1, and Lgr5), highlighting the inhibitory role in the CSC phenotype. More important, evidence was obtained demonstrating that miR-95 knockdown or DUSP5 upregulation exerted an inhibitory effect on the EMT process, cellular processes, and tumor growth. Together these results, miR-95 knockdown inhibited GC development via DUSP5-dependent MAPK pathway.     

Association of genetic polymorphisms in ADH and ALDH2 with risk of coronary artery disease and myocardial infarction: A meta-analysis

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are the major enzymes responsible for alcohol metabolism in humans. Emerging evidences have shown that functional polymorphisms in ADH and ALDH genes might play a critical role in increasing coronary artery disease (CAD) and myocardial infarction (MI) risks; however, individually published studies showed inconclusive results. The aim of this meta-analysis is to evaluate the associations between the genetic polymorphisms of ADH and ALDH genes with susceptibility to CAD and MI. A literature search was conducted on PubMed, Embase, Web of Science and Chinese BioMedical databases from inception through December 1st, 2012. Crude relative risks (RRs) with 95% confidence intervals (CIs) were calculated. Twelve case–control studies were included with a total of 9616 subjects, including 2053 CAD patients, 1436 MI patients, and 6127 healthy controls. Meta-analysis showed that mutant genotypes (GA + AA) of the rs671 polymorphism in the ALDH2 gene were associated with increased risk of both CAD and MI (CAD: RR = 1.20, 95%CI: 1.03–1.40, P = 0.021; MI: RR = 1.32, 95%CI: 1.11–1.57, P = 0.002). However, there were no significant associations of ADH genetic polymorphisms to CAD and MI risks (CAD: RR = 0.92, 95%CI: 0.73–1.15, P = 0.445; MI: RR = 0.93, 95%CI: 0.84–1.03, P = 0.148). In conclusion, this meta-analysis provides strong evidence that ALDH2 rs671 polymorphism may be associated with increased risks of CAD and MI. However, further studies are still needed to accurately determine whether ADH genetic polymorphisms are associated with susceptibility to CAD and MI.