可口革囊星虫(Phascolosoma esculenta)铁结合

以克隆获得的可口革囊星虫(Phasolosma esculenta)、枝吻纽虫(Dendrorhynchus zhejiangensis)、泥蚶(Tegillarca granosa)、缢蛏(Sinonovacula constricta)、仿刺参(Apostichopus japonicus)和白肛海地瓜(Acaudina leucoprocta)6种无脊椎动物的铁结合蛋白基因为基础, 通过NCBI检索下载相应的氨基酸序列, 采用SingalP程序查找信号肽, 用TMHMM程序搜寻预测跨膜区, 采用Clustal W程序多序列比对, 构建进化树。对其编码蛋白的信号肽、跨膜区以及磷酸化位点等进行分析。结果表明, 6种动物的铁结合蛋白都没有信号肽, 也无跨膜区, 不可能是膜上的受体或定位于膜上, 均为胞外蛋白。泥蚶的ferritin有4个磷酸化位点, 仿刺参ferritin有10个, 枝吻纽虫有8个, 白肛海地瓜有9个, 可口革囊星虫和缢蛏的ferritin未搜寻到磷酸化位点。6种铁结合蛋白的疏水性有一定的差异, 最大值在1.0—1.6之间, 最小值在?3.3—?2.8之间。可口革囊星虫和仿刺参的铁结合区域特征序列完全相同, 与文昌鱼、缢蛏、泥蚶、牡蛎、盘鲍有2个氨基酸差异, 与人、小家鼠和叉尾有1个氨基酸差异。     

Marine debris review for Latin America and the wider Caribbean region: from the 1970s until now, and where do we go from here?

The available literature on marine debris from Latin America and the Wider Caribbean Region was collected and linked, reviewing their methodologies and principal results (quantities, composition and spatial-temporal patterns). The study region comprises 52 coastal countries of which only 14 had registers of works on marine debris. A total of 70 works were available and 69 had their full contents accessed. Brazil dominated the available literature with 70% of the documents. Beaches were the most studied environment, and plastics the prevalent form of contamination in the whole region. The exposure of marine biota (species, type of contact, consequences) was highlighted. The studied region, although still little exploited by this sort of research, shows the same contamination patterns observed world-wide. We also contacted 40 researchers in the area, collecting scientific contributions, opinions and suggestions for improvement of this research field. Further advances and new (urgently needed) lines of research are also discussed.     

Oxygen and carbon isotope ratios in the martian atmosphere

Oxygen and carbon isotope ratios in the martian CO₂ are key values to study evolution of volatiles on Mars. The major problems in spectroscopic determinations of these ratios on Mars are uncertainties associated with: (1) equivalent widths of the observed absorption lines, (2) line strengths in spectroscopic databases, and (3) thermal structure of the martian atmosphere during the observation. We have made special efforts to reduce all these uncertainties. We observed Mars using the Fourier Transform Spectrometer at the Canada–France–Hawaii Telescope. While the oxygen and carbon isotope ratios on Mars were byproducts in the previous observations, our observation was specifically aimed at these isotope ratios. We covered a range of 6022 to 6308 cm⁻¹ with the highest resolving power of ν/δν=3.5×10⁵ and a signal-to-noise ratio of 180 in the middle of the spectrum. The chosen spectral range involves 475 lines of the main isotope, 184 lines of ¹³CO₂, 181 lines of CO¹⁸O, and 119 lines of CO¹⁷O. (Lines with strengths exceeding 10⁻²⁷ cm at 218 K are considered here.) Due to the high spectral resolution, most of the lines are not blended. Uncertainties of retrieved isotope abundances are in inverse proportion to resolving power, signal-to-noise ratio, and square root of the number of lines. Laboratory studies of the CO₂ isotope spectra in the range of our observation achieved an accuracy of 1% in the line strengths. Detailed observations of temperature profiles using MGS/TES and data on temperature variations with local time from two GCMs are used to simulate each absorption line at various heights in each part of the instrument field of view and then sum up the results. Thermal radiation of Mars' surface and atmosphere is negligible in the chosen spectral range, and this reduces errors associated with uncertainties in the thermal structure on Mars. Using a combination of all these factors, the highest accuracy has been achieved in measuring the CO₂ isotope ratios: ¹³C/¹²C = 0.978 ± 0.020 and ¹⁸O/¹⁶O = 1.018 ± 0.018 times the terrestrial standards. Heavy isotopes in the atmosphere are enriched by nonthermal escape and sputtering, and depleted by fractionation with solid-phase reservoirs. The retrieved ratios show that isotope fractionation between CO₂ and oxygen and carbon reservoirs in the solid phase is almost balanced by nonthermal escape and sputtering of O and C from Mars.     

H<Emphasis Type="Italic">α</Emphasis> survey of the local volume: Isolated southern galaxies

We present our Hα observations of 11 isolated southern galaxies: SDIG, PGC 51659, E 222-010, E 272-025, E 137-018, IC 4662, Sag DIG, IC 5052, IC 5152, UGCA 438, and E 149-003, with distances from 1 to 7 Mpc. We have determined the total Hα fluxes from these galaxies. The star formation rates in these galaxies range from 10^?1 (IC 4662) to 10^?4 M _⊙ yr^?1 (SDIG) and the gas depletion time at the observed star formation rates lies within the range from 1/6 to 24 Hubble times H ₀ ^?1 .     

湖南城步火成岩锆石SHRIMP U-Pb年龄及其对江南造山带新元古代构造演化的约束

目前对新元古代中期江南造山带构造演化及钦杭结合带南西段构造性质存在不同认识。本文对湘西南城步地区新元古代火山岩和花岗岩进行了锆石SHRIMPU-Pb年龄测定并厘定其构造环境,从而为区域构造演化提供了约束。城步新元古代花岗岩侵入于云场里组变质火山-沉积地层中。云场里组变质火山岩与花岗岩的锆石SHRIMPU-Pb年龄分别为828±10Ma和805.7±9.2Ma。构造环境的地球化学判别图解表明花岗岩形成于岛弧环境;区域地质背景指示云场里组可能形成于活动陆缘弧前盆地。以城步火山岩和花岗岩研究为基础,结合区域地质资料,提出新元古代中期江南造山带西段构造演化过程:872～835Ma期间为陆缘盆地;835～820Ma期间俯冲造山,江南造山带形成基性—超基性岩和早阶段岛弧花岗闪长岩,东侧的城步地区为弧前盆地;820～810Ma期间江南造山带发生弧-陆碰撞;810～800Ma期间江南造山带进入后碰撞环境并形成晚阶段强过铝(黑云母)花岗岩,东侧城步地区因华南洋洋壳俯冲而形成新的岛弧;800Ma后华南进入伸展裂陷盆地演化阶段。上述认识揭示出扬子陆块东南缘的连续岛弧增生过程,同时为钦杭结合带南西段雪峰期"残留洋盆"属性提供了新证据。     

福建南平花岗伟晶岩中的电气石研究

电气石是南平伟晶岩和围岩中分布广泛的一种副矿物,根据化学成分,它们属于镁铁锂电气石亚族,其端员为铁(黑)电气石、镁电气石和锂电气石,其间还有一系列过渡矿物。南平伟晶岩中除未发现端员锂电气石外,其他端员及过渡系列电气石均十分发育,这在国内外同类伟晶岩中十分少见。不同成分电气石分布于不同类型伟晶岩及同一伟晶岩分异演化的不同阶段。本文在对电气石的化学成分、物理性质、产状等较详阐述基础上,对它们的演变规律及形成环境进行了讨论,这对于探讨南平伟晶岩的形成及寻找稀有金属伟晶岩有重要意义。     

Distribution and Forming Model of Fluvial Terrace in the Huangshui Catchment and its Tectonic Indication

<正>The Huang Shui River,a main tributary of the Yellow River,crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation.The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping.Three terraces in the Haiyan Basin,four terraces in the Huangyuan Basin,19 terraces in the Xi'ning Basin(the four high terraces may belong to another river),nine terraces in the Ping'an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized.Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River,which is located at the margin of Tibet,are different from that of the rivers at other regions.The formation process of the terrace is more complicated at the Huang Shui catchment:both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins,indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins.A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper.First,the equilibrium state of the river is broken because of climatic change and/or tectonic movement,and the river incises in all basins in the whole catchment until reaching a new equilibrium state.Then,the downstream basin subsides quickly and the equilibrium state is broken again,and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again.Finally,the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins.The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment.These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin.Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau.     

三峡蓄水后典型河段分形维数的变化分析

针对三峡工程蓄水后下游河道河床表面形态的变化,采用分形维数对河床表面形态进行量化,并分析河道冲淤调整特点,对河床表面分形维数(BSD)的变化特点及物理意义进行探讨。结果表明,BSD与河床各个剖面形态之间的关系是整体与部分的关系,BSD能全面地反映床面形态的复杂程度。三峡蓄水后,宜昌-虎牙滩和宜都河段BSD明显增大,关洲河段增大幅度较小,而芦家河河段BSD值略有减小,同时,各河段BSD的变化可在一定程度上表征三峡蓄水后下游河道河床综合阻力的调整结果。可通过对各河段演变趋势的分析,来预测其BSD的变化,进而为分析其阻力和水位的变化趋势提供依据。