Critical role of Toll‐like receptor 2 in Bacteroides fragilis‐mediated immune responses in murine peritoneal mesothelial cells

In this study, the role of Toll‐like receptor 2 (TLR2) in immune responses of murine peritoneal mesothelial cells against Bacteroides fragilis was investigated. Enzyme linked immunosorbent assay was used to measure cytokines and chemokines. Activation of nuclear factor κB (NF‐κB‐α) and mitogen‐activated protein kinases (MAP kinases) was investigated by western blot analysis. B. fragilis induced production of interleukin‐6, chemokine (C‐X‐C motif) ligand 1 (CXCL1) and chemokine (C‐C motif) ligand 2 (CCL2) in wild type peritoneal mesothelial cells; this was impaired in TLR2‐deficient cells. In addition, in response to B. fragilis, phosphorylation of inhibitory NF‐κB‐α and c‐Jun N‐terminal kinase mitogen‐activated protein kinase (MAPK) was induced in wild type mesothelial cells, but not in TLR2‐deficient cells,. Inhibitor assay revealed that NF‐κB and MAPKs are essential for B. fragilis‐induced production of CXCL1 and CCL2 in mesothelial cells. These findings suggest that TLR2 mediates immune responses in peritoneal mesothelial cells in response to B. fragilis.     

MicroRNA-processing enzyme Dicer is required in epicardium for coronary vasculature development

The epicardium is a sheet of epithelial cells covering the heart during early cardiac development. In recent years, the epicardium has been identified as an important contributor to cardiovascular development, and epicardium-derived cells have the potential to differentiate into multiple cardiac cell lineages. Some epicardium-derived cells that undergo epithelial-to-mesenchymal transition and delaminate from the surface of the developing heart subsequently invade the myocardium and differentiate into vascular smooth muscle of the developing coronary vasculature. MicroRNAs (miRNAs) have been implicated broadly in tissue patterning and development, including in the heart, but a role in epicardium is unknown. To examine the role of miRNAs during epicardial development, we conditionally deleted the miRNA-processing enzyme Dicer in the proepicardium using Gata5-Cre mice. Epicardial Dicer mutant mice are born in expected Mendelian ratios but die immediately after birth with profound cardiac defects, including impaired coronary vessel development. We found that loss of Dicer leads to impaired epicardial epithelial-to-mesenchymal transition and a reduction in epicardial cell proliferation and differentiation into coronary smooth muscle cells. These results demonstrate a critical role for Dicer, and by implication miRNAs, in murine epicardial development.     

Sphingosine kinase regulates the sensitivity of Dictyostelium discoideum cells to the anticancer drug cisplatin

The drug cisplatin is widely used to treat a number of tumor types. However, resistance to the drug, which remains poorly understood, limits its usefulness. Previous work using Dictyostelium discoideum as a model for studying drug resistance showed that mutants lacking sphingosine-1-phosphate (S-1-P) lyase, the enzyme that degrades S-1-P, had increased resistance to cisplatin, whereas mutants overexpressing the enzyme were more sensitive to the drug. S-1-P is synthesized from sphingosine and ATP by the enzyme sphingosine kinase. We have identified two sphingosine kinase genes in D. discoideum--sgkA and sgkB--that are homologous to those of other species. The biochemical properties of the SgkA and SgkB enzymes suggest that they are the equivalent of the human Sphk1 and Sphk2 enzymes, respectively. Disruption of the kinases by homologous recombination (both single and double mutants) or overexpression of the sgkA gene resulted in altered growth rates and altered response to cisplatin. The null mutants showed increased sensitivity to cisplatin, whereas mutants overexpressing the sphingosine kinase resulted in increased resistance compared to the parental cells. The results indicate that both the SgkA and the SgkB enzymes function in regulating cisplatin sensitivity. The increase in sensitivity of the sphingosine kinase-null mutants was reversed by the addition of S-1-P, and the increased resistance of the sphingosine kinase overexpressor mutant was reversed by the inhibitor N,N-dimethylsphingosine. Parallel changes in sensitivity of the null mutants are seen with the platinum-based drug carboplatin but not with doxorubicin, 5-fluorouracil, and etoposide. This pattern of specificity is similar to that observed with the S-1-P lyase mutants and should be useful in designing therapeutic schemes involving more than one drug. This study identifies the sphingosine kinases as new drug targets for modulating the sensitivity to platinum-based drugs.     

角蛋白HGTP及其对羊毛发育的影响

羊毛的主要成分是角蛋白,其组分高甘氨酸-酪氨酸蛋白(HGTP)家族成员KAP6、KAP7和KAP8基因表达对羊毛细度和弯曲等特性具有重要影响。本文从羊毛的组成、角蛋白的生物学特征以及HGTP基因定位和表达对细度的影响等方面进行了综述,旨在为羊毛发育调控研究提供理论参考。     

大鼠脑缺血-再灌注前后血浆TXB2及6-Keto-PGF1α含量的变化

目的:本实验旨在揭示脑缺血-再灌注损伤前后大鼠血浆血栓素B2(TXB2)及6-酮前列腺环素F1(6-Keto-PGF1α)的动态变化.方法:制作脑缺血-再灌注大鼠模型,45只健康SD大鼠随机分为正常对照组、模型组和假手术组大鼠.在术后1天、3天、5天和7天分别观察大鼠血浆TXB2和6-Keto-PGF1α含量.结果:线栓大脑中动脉后造成脑缺血,血浆TXB2含量和TXB2/6-Keto-PGF1α比值明显高于假手术组和正常对照组(p＜0.05或0.01),在缺血第1天最显著.结论:脑缺血-再灌注损伤后,血浆TXB2和TXB2/6-Keto-PGF1α的变化规律可为临床缺血性脑损伤治疗提供重要参考.     

Hydrological regulation drives regime shifts: evidence from paleolimnology and ecosystem modeling of a large shallow Chinese lake

Quantitative evidence of sudden shifts in ecological structure and function in large shallow lakes is rare, even though they provide essential benefits to society. Such ‘regime shifts’ can be driven by human activities which degrade ecological stability including water level control (WLC) and nutrient loading. Interactions between WLC and nutrient loading on the long‐term dynamics of shallow lake ecosystems are, however, often overlooked and largely underestimated, which has hampered the effectiveness of lake management. Here, we focus on a large shallow lake (Lake Chaohu) located in one of the most densely populated areas in China, the lower Yangtze River floodplain, which has undergone both WLC and increasing nutrient loading over the last several decades. We applied a novel methodology that combines consistent evidence from both paleolimnological records and ecosystem modeling to overcome the hurdle of data insufficiency and to unravel the drivers and underlying mechanisms in ecosystem dynamics. We identified the occurrence of two regime shifts: one in 1963, characterized by the abrupt disappearance of submerged vegetation, and another around 1980, with strong algal blooms being observed thereafter. Using model scenarios, we further disentangled the roles of WLC and nutrient loading, showing that the 1963 shift was predominantly triggered by WLC, whereas the shift ca. 1980 was attributed to aggravated nutrient loading. Our analysis also shows interactions between these two stressors. Compared to the dynamics driven by nutrient loading alone, WLC reduced the critical P loading and resulted in earlier disappearance of submerged vegetation and emergence of algal blooms by approximately 26 and 10 years, respectively. Overall, our study reveals the significant role of hydrological regulation in driving shallow lake ecosystem dynamics, and it highlights the urgency of using multi‐objective management criteria that includes ecological sustainability perspectives when implementing hydrological regulation for aquatic ecosystems around the globe.     

人骨髓间充质干细胞在成年大鼠脑内的迁移及分化

骨髓间充质干细胞 (mesenchymalstemcells,MSCs)是目前备受关注的一类具有多向分化潜能的组织干细胞 ,体外可以分化为骨、软骨、脂肪等多种细胞。因此 ,MSCs是细胞治疗和基因治疗的种子细胞之一。为了探索MSCs的迁移和分化趋势 ,为帕金森病 (Parkinsondisease,PD)的干细胞治疗提供理论和实验依据 ,本实验将体外扩增并转染增强型绿色荧光蛋白 (enhancedgreenfluorescentprotein ,EGFP)的人骨髓MSCs注入PD大鼠脑内纹状体 ,观察了人骨髓MSCs在大鼠脑内的存活、迁移、分化以及注射MSCs前后大鼠的行为变化。结果表明 ,人骨髓MSCs在大鼠脑内可存活较长时间 ( 10周以上 ) ;随着时间的延长 ,MSCs迁移范围扩大 ,分布于纹状体、胼胝体、皮质以及脑内血管壁 ;免疫组化法检测证实MSCs在大鼠脑内表达人神经丝蛋白 (neurofilament,NF)、神经元特异性烯醇化酶 (neuron specificeno lase,NSE)以及胶质原纤维酸性蛋白 ( glialfibrillaryacidprotein ,GFAP) ;PD大鼠的异常行为有所缓解 ,转圈数由 8 86±2 0 9r/min下降到 4 87± 2 0 6r/min ,统计学分析P <0 0 5为差异显著。以上观察结果表明 ,骨髓MSCs有望成为治疗PD的种子细胞     

17个新的C2H2型锌指基因片段的分离与克隆

按照Ｃ２Ｈ２型锌指基因保守结构域的ＤＮＡ序列设计一对简并引物,以人基因组ＤＮＡ为模板进行ＰＣＲ同源扩增,将由此获得的锌指基因片段为探针,从人胎肾、骨骼肌、骨骼组织的ｃＤＮＡ分子库中筛选到２２个Ｃ２Ｈ２型锌指蛋白ｃＤＮＡ片段,经国际ＮＣＢＩ数据库查询检索,其中１７个为新的锌指基因片段。对从胎肾ｃＤＮＡ分子库中分离到的Ｋ３－４和Ｋ５－１２克隆进行了表达谱分析,发现Ｋ３－４在肾脏中的表达量明显高于其他几