Functional morphology of chloride cells in killifish Fundulus heteroclitus, a euryhaline teleost with seawater preference

ABSTRACT:   Recent advances in the functional morphology of chloride cells in killifish Fundulus heteroclitus , a euryhaline teleost with seawater (SW) preference, were reviewed. Immunocytochemical detection of chloride cells with anti-Na⁺/K⁺-ATPase revealed transitional processes of the chloride cell distribution during early life stages. Chloride cells first appear in the yolk-sac membrane at an early embryonic stage, followed by their appearance in the body skin in the later embryonic stages. The principal site for the chloride cell distribution then shifts from the yolk-sac membrane and body skin during embryonic stages to the gills and opercular membrane in larval and later developmental stages. Morphologically distinct SW- and freshwater (FW)-type chloride cells were identified in adult killifish adapted to SW and FW, respectively. Both types of chloride cells are equally active in the two environments, but exert different ion-transporting functions. Following direct transfer of killifish from SW to FW, SW-type chloride cells were transformed into FW-type cells as a short-term response, followed by the promotion of chloride cell replacement as a long-term response. In killifish acclimated to low NaCl (0.1 mM) FW, intense immunoreactivity for vacuolar-type proton pump (V-ATPase) was detected in the basolateral membrane of FW-type chloride cells, whereas the immunoreactivity was much weaker in fish acclimated to FW with higher NaCl concentrations (1.0 and 10.0 mM). These results suggest the occurrence of active ion absorption in FW-type chloride cells and the involvement of V-ATPase in ion-absorbing mechanisms. In view of recent advances in this field, future chloride cell research should be considered in relation to the functional diversity of chloride cells.     

浅谈水域岩土工程勘察及钻探工艺

本文作者根据自己多年的工程实践总结出在不同水深，不同地层中如何采用水上钻探的一些方法及工艺。     

运用现场测试技术合理确定泵站改造技术措施

通过实例，论述了运用泵站测试技术综合分析，找出泵站运行中存在的出流小、效率低、耗能高的问题。采取合理选取泵型、车削叶轮、调整叶片安装角度、出水管形成虹吸等不同的工程技术措施，提高了泵站装置效率。达到了降低成本、提高经济效益的目的。     

Effects of leptin on BSEP protein expression and signaling pathway in HepG2 cells

AIM: To investigate the effects of leptin on the expression of bile salt export pump (BSEP) and signaling pathway in human hepatocellular carcinoma cell line HepG2. METHODS: HepG2 cells were cultured in vitro. Leptin at concentrations of 10^-8, 10^-7 and 10^-6 mol/L was used as a stimulating factor. The protein levels of adenosine monophosphate-activated protein kinase alpha subunit (AMPKa), phosphorylated AMPKa (p-AMPKa) and BSEP in the HepG2 cells at 24 h, 48 h and 72 h were detected by Western blotting. The optimal culture time and leptin concentration were selected, and compound C at concentration of 10 μmol/L was added to this group. The protein expression of BSEP was detected by Western blotting. RESULTS: Intervention of HepG2 cells with leptin for 72 h increased the protein expression of AMPKa gradually in a concentration-dependent manner, and leptin at concentration of 10^-6 mol/L induced the strongest AMPKa expression (P<0.01). Intervention of HepG2 cells with leptin for 24 h increased the phosphorylation level of AMPKa gradually in a dose-dependent manner (P<0.01). The effect of leptin on the increase in the protein expression of p-AMPKa was also in a time-dependent manner (P<0.01). After intervention with different concentrations of leptin for 24 h, the protein expression of BSEP in the HepG2 cells was gradually increased by the stimulation of leptin in a concentration- and time-dependent manner (P<0.01). Compared with NC group, the protein expression of BSEP in 10^-6 mol/L leptin group and 10^-6 mol/L leptin+10 μmol/L compound C group was increased at 72 h (P<0.01), and that in 10^-6 mol/L leptin+10 μmol/L compound C group was lower than that in 10^-6 mol/L leptin group at 72 h (P<0.01). CONCLUSION: Leptin promotes the protein expression of BSEP in HepG2 cells by leptin-AMPK-BSEP signaling pathway. Leptin promotes the increases in AMPKa protein and the level of phosphorylation of AMPKa in HepG2 cells.     

AutoCAD环境下离心泵性能预测软件的开发

对AutoCAD图形系统进行了二次开发，将AutoCAD缓图资源和Windows编程风格进行了完美的结合，开发出了离心性能预测软件。简要介绍了该离心泵性能预测软件在实现过程中的特点和软件所具备的功能，深入阐述了离心泵性能预测的实现原理主性能曲线的绘制过程。     

潜水泵站选型中应注意的事项

为了解决由于泵站在设计中泵选型不合理而出现的水泵不能正常运行的问题,从水泵生产厂家的角度,通过具体实例,对泵站设计的各个环节进行分析,得出潜水泵运行时的工况点与潜水泵站设计形式及泵选型有关的结论,分析潜水泵站在选型中应注意的事项,给出了选型方法.     

液体射流泵内部三维流场的数值模拟

应用FLUENT6．0软件对液体射流泵三维流场进行了计算分析。在前处理软件GAMBIT2．1．6中将泵内的流场划分为71153个计算单元。计算中采用可实现K-6双方程模型，边界条件为压力进口、压力出口，速度、压力采用SIMPLEC算法。计算得出了射流泵内部的流场分布，其结果可以为射流泵的设计提供依据。     

解决大型排水泵站超驼峰运行问题

针对大型排水泵站在超驼峰水位下运行的工程问题，介绍了压缩空气及活页式快速闸门两种断流装置。根据大型排水泵站防洪特点，提出了完成超驼峰水位下，启动、停机及防止倒灌等一系列断流措施，快速、安全、经济地解决了各种大型排水泵站超驼峰水位运行问题。     

面积比原理和泵的性能

介绍了离心泵的面积比原理,在假设v_(u1)=0及在最高水力效率点处v_2=v_t时,对面积比Y作了理论推导,获得了在Y<1,Y=1和Y>1时扬程曲线及轴功率曲线的大致形状。在试验的基础上,对无过载离心泵,建议Y在1.0～2.0范围内选择。     

轴流泵出口能量分布特性与测定

试验发现，用常规方法测定的轴流泵出口能量偏小。为揭示其原因，用五孔探针测定轴流泵出口流场，结果表明，出流具有较大的周向流速，断面轴向流速分布很不均匀，各点单位势能不等，出水管内为螺旋流动，属急变流，简要分析了它的形成机理，并给出了用常规方法测定轴流泵出口能量的修正方法。