Assessment of cytochrome P450 1A in harbour seals (Phoca vitulina) using a minimally-invasive biopsy approach

Biomarkers of organochlorine exposure, such as the induction of cytochrome P450 1A (CYP1A), can be used to assess the impact of environmental contaminants on the health of free-ranging marine mammal populations. The objective of the present study was to measure CYP1A in skin and liver biopsies obtained from live harbour seals (Phoca vitulina). Twelve harbour seal pups, aged three to five weeks, were captured from the Fraser River estuary, British Columbia, Canada, and temporarily held in captivity. Skin ( approximately 60 mg) and liver ( approximately 40 mg) biopsies, obtained while seals were under general anaesthesia, yielded sufficient tissue for the measurement of CYP1A by immunoblot analysis and ethoxyresorufin O-deethylase activity. A short-term exposure experiment, in which harbour seals (n=3) were treated orally with beta-naphthoflavone (BNF), resulted in increased hepatic and cutaneous CYP1A protein levels, consistent with observations in other mammals. This study is the first to measure CYP1A in skin and liver biopsies from live harbour seals and to report in vivo BNF-associated CYP1A induction in a marine mammal. The results demonstrate that microsamples collected using minimally-invasive techniques can provide toxicologically-relevant information form marine mammals.     

Cycle anatomy and variability in the storm-dominated type cincinnatian (Upper Ordovician): coming to grips with cycle delineation and genesis

Although parasequence and sequence are scale-independent terms, they are frequently applied only to specific scales of cycles. For example, meter-scale cycles are commonly assumed to be parasequences or PACs. In the Upper Ordovician Kope and Fairview Formations of northern Kentucky, we examined a succession of 50 meter-scale cycles that have been variously interpreted as deepening-upward, shallowing-upward, or showing no relationship with water depth. Our analysis shows that these cycles, characterized by shifts in storm-bed proximality, are highly variable in their thickness and internal construction. Most cycles are best considered high-frequency sequences, because deepening-upward intervals are common, and many cycles contain evidence of abrupt basinward shifts in facies as expected at sequence boundaries. A minority fit the parasequence model of shallowing-upward cycles bounded by flooding surfaces. Larger, 20 m scale cycles are defined by systematic thickening and thinning trends of meter-scale cycles. However, meter-scale cycles do not display any systematic trends in cycle anatomy as a function of position within the 20 m cycles or position within the Kope and Fairview Formations. The high cycle variability and the lack of systematic stratigraphic organization with respect to longer-term cyclicity reflect either the irregularity of relative sea-level changes, the poor recording of sea-level changes in this deep-water setting, or the generation of these cycles by climate-induced cyclicity in storm intensity. These three mechanisms would generate similar patterns at the outcrop scale, so it is not possible at the present to distinguish between them.     

黑龙江依兰地区蓝片岩相变质作用及其演化

依兰地区蓝片岩作为黑龙江杂岩的重要组成部分,其变质作用演化问题一直存在较大争议。本文通过对依兰地区蓝片岩的岩相学及矿物微区化学成分的研究,并运用PERPLE_X软件,在Na_2O-CaO-K_2O-MnO-FeO-MgO-Al_2O_3-SiO_2-H_2O-TiO_2-O(Fe_2O_3)(NCKMnFMASHTO)体系下对石榴石冻蓝闪石片岩(g-brs-wnc-act-phn-chl-ep-ab-stlp)、绿泥绿帘蓝闪石片岩(gl-brs-wnc-act-chl-ep-stlp)和白云母蓝闪石片岩(gl-wnc-phn-ab-ep-chl-sph)进行了相平衡模拟,并分别获得了500~525℃/1.14~1.2GPa、480℃/1.4GPa、450~500℃/0.95~1.2GPa峰期变质作用的温压条件,其峰期变质级别都达到了绿帘-蓝片岩相。结合前人发表的地球化学和年代学数据,建立了蓝片岩相岩石的顺时针变质演化P-T轨迹。研究区蓝片岩的形成标志着新生洋壳的俯冲作用,同时代表古亚洲洋构造域的结束和环太平洋构造域的开始。相平衡模拟中,P-T轨迹记录了峰期前温压条件递增的过程,温度峰期与压力峰期同时到达,说明蓝片岩相变质作用是在俯冲过程中实现的,而不是折返过程中达到的。减压阶段的轨迹近于平行追溯进变质轨迹,揭示与进变质过程相似的地热体制下(11～14℃/km),相对缓慢的抬升过程     

变质流体研究的意义和途径

变质流体作为变质岩石的重要组成部分,以流体包裹体的形式被圈闭在矿物中。它是变质作用过程峰期变质阶段矿物结晶时而封存的与矿物处于平衡状态的流体相。流体包裹体是矿物结晶时流体环境的唯一真实和客观的记录。是唯一能够获得的变质过程流体性质和物化条件的实际样品。流体包裹体的观察和认识随着岩石学研究的进展早已开