Silica retention in the Three Gorges Reservoir

A mass balance of dissolved silica (DSi) based on daily measurements at the inflow and outflow of the Three Gorges Reservoir (TGR) in 2007 and a more precise budget, with inflow, outflow, primary production, biogenic silica (BSi) settlement, dissolution of BSi in the water column and flux of DSi at the sediment–water interface in the dry season (April) of 2007 were developed. We address the following question: How much does the Three Gorges Dam (TGD) affect silica transport in the TGR of the Changjiang River (Yangtze River)? The DSi varied from 71.1 to 141 μmol/l with an average of 108 μmol/l, and it ranged between 68.1 and 136 μmol/l, with an average of 107 μmol/l in inflow and outflow, respectively, in the TGR in 2007. The linear relationship of DSi between inflow and outflow water is significant (r = 0.87, n = 362, p < 0.01). Along the main stream of the TGR, the DSi concentration decreases with an average concentration of 84.0 μmol/l in the dry season. However, the stratification of DSi was not obvious in the main channel of the TGR in the dry season. The BSi is within the range of 0.04–5.00 μmol/l, with an average concentration of 2.1 μmol/l in the main channel of the TGR, while it is much higher in Xiangxi Bay (1.30–47.7 μmol/l, 13.1 μmol/l) than in the main stream of the TGR and the other bays. After the third filling of the TGR, approximately 3.8% of the DSi was retained by the TGR based on a 12-month monitoring scheme in 2007, which would slightly reduce nutrient fluxes of the Changjiang River to the East China Sea (2%). DSi was lost during January to June and November, whereas the additions of DSi were found during the other months in 2007. The budget results also indicate that there is a slight retention of DSi. The retention of DSi in the reservoir is approximately 2.9%, while BSi is approximately 44%. Compared with the total silica load, the retention of DSi and BSi in the reservoir is only 5.0% in the dry season. With its present storage capacity, the reservoir does not play an important role as a silica sink in the channel of the TGR. The DSi load is significantly related to discharge both in inflow and outflow waters (p < 0.01). DSi retention, to some extent, is the runoff change due to impoundment.     

Decreased levels of free d-aspartic acid in the forebrain of serine racemase (Srr) knock-out mice

d-Serine, an endogenous co-agonist of the N-methyl-d-aspartate (NMDA) receptor is synthesized from l-serine by serine racemase (SRR). A previous study of Srr knockout (Srr-KO) mice showed that levels of d-serine in forebrain regions, such as frontal cortex, hippocampus, and striatum, but not cerebellum, of mutant mice are significantly lower than those of wild-type (WT) mice, suggesting that SRR is responsible for d-serine production in the forebrain. In this study, we attempted to determine whether SRR affects the level of other amino acids in brain tissue. We found that tissue levels of d-aspartic acid in the forebrains (frontal cortex, hippocampus and striatum) of Srr-KO mice were significantly lower than in WT mice, whereas levels of d-aspartic acid in the cerebellum were not altered. Levels of d-alanine, l-alanine, l-aspartic acid, taurine, asparagine, arginine, threonine, γ-amino butyric acid (GABA) and methionine, remained the same in frontal cortex, hippocampus, striatum and cerebellum of WT and mutant mice. Furthermore, no differences in d-aspartate oxidase (DDO) activity were detected in the forebrains of WT and Srr-KO mice. These results suggest that SRR and/or d-serine may be involved in the production of d-aspartic acid in mouse forebrains, although further detailed studies will be necessary to confirm this finding.     

Breast cancer-derived K172N,D301V mutations abolish Na/H exchanger regulatory factor 1 inhibition of platelet-derived growth factor receptor signaling

Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) is a scaffold protein known to interact with a number of cancer-related proteins. nherf1 Mutations (K172N and D301V) were recently identified in breast cancer cells. To investigate the functional properties of NHERF1, wild-type and cancer-derived nherf1 mutations were stably expressed in SKMES-1 cells respectively. NHERF1-wt overexpression suppressed the cellular malignant phenotypes, including proliferation, migration, and invasion. nherf1 Mutations (K172N and D301V) caused complete or partial loss of NHERF1 functions by affecting the PTEN/NHERF1/PDGFRβ complex formation, inactivating NHERF1 inhibition of PDGF-induced AKT and ERK activation, and attenuating the tumor-suppressor effects of NHERF1-wt. These results further demonstrated the functional consequences of breast cancer-derived nherf1 mutations (K172N and D301V), and suggested the causal role of NHERF1 in tumor development and progression.     

酸雨背景下缙云山典型林分凋落物量和营养元素含量及其释放特征

选取缙云山针阔混交林、常绿阔叶林、楠竹林和灌木林作为研究对象,对4种林分的凋落物储量和营养元素释放量等进行观测,并应用室内模拟酸雨实验对4种林分凋落物进行淋溶模拟。结果表明:缙云山各林分现存凋落物厚度为1.4～4.5 cm,具有明显的分层结构;林分未分解U层、半分解S层和分解D层现存凋落物量分别为1.97～8.59、2.84～10.18和3.58～17.43 t·hm-2,林分年凋落物量为2.17～9.86 t·hm-2·a-1,凋落物总储量为14.21～32.42 t·hm-2,凋落物分解常数为0.15～0.31,林下凋落物分解95%时所需时间针阔混交林和楠竹林均在10年以上,凋落物分解速率比较缓慢;林下凋落物层营养元素含量以Ca、N为主,Fe、K、Mg次之;凋落物总的营养元素释放率表现为常绿阔叶林(0.80)>灌木林(0.72)>针阔混交林(0.50)>楠竹林(-0.17);与叶片相比,凋落物中N、K、Mn 3种营养元素含量明显降低;为探明酸雨影响营养元素循环的作用机理,对模拟酸雨的离子含量与凋落物淋滤液盐基离子含量进行了分析,其相关性大小表现为楠竹林(相关系数0.895)>针阔混交林(0.826)>灌木(0.700)>常绿阔叶林(0.699),楠竹林凋落物营养元素的淋滤受酸雨影响最大,常绿阔叶林受其影响最弱;推测在这一过程中以凋落物的吸附作用为主。     

FKBP52对小鼠前列腺发育的影响

目的通过FKBP52基因敲除小鼠模型探索FKBP52在小鼠前列腺发育过程中的作用。方法分别对胚胎第17．5天、新生的和出生后3周的野生型和FKBP52基因敲除小鼠的前列腺进行切片HE染色,观察不同发育时期里野生型和FKBP52基因敲除小鼠前列腺发育的异同。结果（1）小鼠前列腺发育的起始不依赖于FKBP52基因的参与;（2）随着胚胎的发育,FKBP52在雄鼠前列腺发育中的作用逐渐显现出来,即FKBP52的缺失会导致前列腺叶发育受阻,最终不能形成成熟的前列腺。结论FKBP52在小鼠前列腺的发育过程中具有重要作用,它不参与前列腺的发育起始过程,但其缺失会导致前列腺发育受阻,即不能形成成熟的前列腺。     

人参皂甙Rb1对心力衰竭大鼠蛋白激酶R样内质网激酶途径的影响

目的探讨人参皂甙Rbl（Gs—Rbl）改善阿霉素所致心力衰竭（HF）效应是否与调整蛋白激酶R样内质网激酶（PERK）通路有关。方法阿霉素（Adr）诱导的HF大鼠随机分为HF组（n=15）和Gs．Rbl组（70rng／kg／d,n=17）,另随机选取同龄大鼠作为对照组（n=10）。干预结束并进行心脏超声检查后,TUNNEL检测心肌细胞凋亡率（AR）,Western blot和Rt-PCR检测葡萄糖调节蛋白78（GRP78）、PERK、p-PERK、真核细胞起始因子2-（elF2a）、p-elF2a、C／EBP同源蛋白（CHOP）和cleavedcaspase-12。结果1．Adr干预成功构建HF模型,Gs—Rbl显著提高左室射血分数（LVEF）和降低心肌细胞AR（P〈O．01）;2．HF组GRP78mRNA和蛋白均显著高于对照组,Gs—Rbl显著低于HF组和对照组二组的表达（P〈0．01）;3．Gs—Rbl显著降低HF大鼠PERK和p-PERK表达（P〈0．01）;4．HF导致elF2amRNA和蛋白、p-elF2a显著升高,Gs—Rbl显著下调三者的表达（P〈O．01）;5．HF组CHOPmRNA和蛋白显著高于对照组,Gs—Rbl组显著抑制其表达（P〈0．01）;6．Gs—Rbl显著抑制阿霉素所致的caspase-121TIRNA和cleaved caspase-12蛋白表达（P〈0．01）。结论Gs—Rbl通过调节PERK内质网通路介导其改善HF效应。     

Altitudinal variation in growth, photosynthetic capacity and water use efficiency of Abies faxoniana Rehd. et Wils. seedlings as revealed by reciprocal transplantations

Altitudinal variation in morphological, physiological and biochemical characteristics between two provenances of Abies faxoniana Rehd. et Wils. from contrasting elevations (3,500 and 2,850 m) was investigated by reciprocal transplantations in the eastern Qinghai-Tibetan Plateau. From each altitude, 54 seedlings were selected, of which 27 seedlings were simply transplanted at their original altitude, while the other 27 seedlings were reciprocally transplanted to another altitude. The results showed that there is evident altitudinal variation in growth, photosynthetic capacity and water use efficiency among A. faxoniana seedlings. Transplantation of seedlings to a lower altitude decreased the leaf pigment content, leaf N content and water use efficiency, but increased CE, P _n, LMR and PNUE, consequently promoting NAR, the biomass accumulation and branchlet length increment. Besides, the increase in the C/N ratio reduced the risk of pathogen attack. Based on the substantial plasticity in the responses of the seedlings, we infer that the ongoing climate warming might facilitate the growth of A. faxoniana seedlings at high altitudes.     

Optimization of human umbilical cord mesenchymal stem cell isolation and culture methods

Human umbilical cord mesenchymal stem cells (hUCMSCs) are considered to be an ideal replacement for bone marrow MSCs. However, up to date, there is no convenient and efficient method for hUCMSC isolation and culture. The present study was carried out to explore the modified enzyme digestion for hUCMSC in vitro. Conventional enzyme digestion, modified enzyme digestion, and tissue explant were used on hUCMSCs to compare their efficiencies of isolation and culture, to observe primary cell growth and cell subculture. The results show that the cells cultured using the tissue explant method had a longer culture cycle (P < 0.01) and lower yield of primary cells per centimetre of umbilical cord (P < 0.01) compared with the two enzyme digestion methods. Subculture adherence and cell doubling took significantly less time with the tissue explant method (P < 0.05) than with the conventional enzyme digestion method; however, there was no significant difference between the tissue explant method and the modified enzyme digestion method (P > 0.05). Comparing two enzyme digestion methods, the modified method yielded more cells than did the conventional method (P < 0.01), and primary cell adherence took significantly less time with the modified method than with the conventional method (P < 0.05). Cell cycle analysis of the third-generation hUCMSCs cultured by modified enzyme digestion method indicated that most cells were quiescent. Immunofluorescence staining showed that these cells expressed MSC markers CD44 and CD90. And Von Kossa and oil red O staining detection showed that they could be differentiated into osteoblasts and adipocytes with induction medium in vitro. This study suggests that hUCMSC isolation and culture using 0.2 % collagenase II at 37 °C for digestion of 16–20 h is an effective and simple modified enzyme digestion method.