Different fates of the chloroplast tufA gene following its transfer to the nucleus in green algae

Previous work suggested that the tufA gene, encoding protein synthesis elongation factor Tu, was transferred from the chloroplast to the nucleus within the green algal lineage giving rise to land plants. In this report we investigate the timing and mode of transfer by examining chloroplast and nuclear DNA from the three major classes of green algae, with emphasis on the class Charophyceae, the proposed sister group to land plants. Filter hybridizations reveal a chloroplast tufA gene in all Ulvophyceae and Chlorophyceae, and in some but not all Charophyceae. One charophycean alga, Coleochaete orbicularis, is shown to contain an intact but highly divergent chloroplast tufA gene, whose product is predicted to be nonfunctional in protein synthesis. We propose that a copy of the tufA gene was functionally transferred from the chloroplast to the nucleus early in the evolution of the Charophyceae, with chloroplast copies of varying function being retained in some but not all of the subsequently diverging lineages. This proposal is supported by the demonstration of multiple tufA-like sequences in Coleochaete nuclear DNA and in nuclear DNA from all other Charophyceae examined

Ostracode-based aminostratigraphy and aminochronology of a tufa system in central Spain

In the Priego area, central Spain, extensive tufa deposits are located in three small tributaries located at the head of the 1000 kmlong Tagus River. The deposits are originated after karst-origin running waters emerged from the confines of the canyons and expanded outward. Old tufa deposits of Priego are mainly present as terraced alluvial plain deposits where different autochthonous and allochthonous facies appear. Extraclastic deposits of quartzite and limestone clasts derived from Mesozoic rocks are interbedded with the tufa marking pulsatory high-flow periods. Using the geomorphologic analysis six terraced levels were differentiated and sampled for ostracode amino acid racemization analysis. D/L ratios of aspartic acid and glutamic acid were used for dating purposes. Cluster analysis defined six aminozones (AMI-AM7) which were dated as follows: AMI: 407 ± 12 ka oxygen isotope stages (OIS 11); AM2: 263 ± 14 ka (OIS 7e); AM3: 181 ± 17 ka (OIS 7a); AM4: 136± 13 ka (OIS 5-6); AM5: 108 ± 14 ka (OIS 5); AM7: 11 ± 4 ka (OIS 1), indicating that tufa deposition took place during warm periods. Models of riverine and riverinebarrage tufa accumulation indicate that their maximum build-up took place between the canyon mouth and the point of depletion of dissolved CO2, and this affected the elevation of the top of the deposits and their relative chronology

Constructive waterfalls

The excavation of valleys by waterfalls is one of the best known and most effective processes by which rivers cut down the surface of the earth. The influence of waterfalls is usually regarded as solely destructive, and as always helping to lower the land. They undermine and cut backward the rock faces over which they fall : by this recession they excavate deep gorges ; and the existence of these gorges enables the adjacent country to be lowered to the level of the valIey floors. The waterfalls, moreover, empty any lakes they rnay reach in their retreat, while the ravines below the falls may drain the springs and thus desiccate the neighbouring hihlands. Observations in various countries had suggested to me that waterfalls may sometimes be constructive in stead of destructive, and that they may reserse their usual procedure, advancing instead of retreating, filling valleys instead of excavating them, and forrning alluvial plains and lakes instead of destroying them. The best illustrations I have seen of such advancing, constructive waterfalls are on some rivers of Dalmatia and Bosnia, where they occur in various stages of development. ..

Floodplain environmental change during the younger dryas and holocene: Evidence from the lower kennet valley, south central England

Many lowland rivers across northwest Europe exhibit broadly similar behavioural responses to glacial-interglacial transitions and landscape development. Difficulties exist in assessing these, largely because the evidence from many rivers remains limited and fragmentary. Here we address this issue in the context of the river Kennet, a tributary of the Thames, since c. 13,000 cal. BP). Some similarities with other rivers are present, suggesting that regional climatic shifts are important controls. The Kennet differs from the regional pattern in a number of ways. The rate of response to sudden climatic change, particularly at the start of the Holocene and also mid-Holocene forest clearance, appears very high. This may reflect abrupt shifts between two catchment scale hydrological states arising from contemporary climates, land use change and geology. Stadial hydrology is dominated by nival regimes, with limited winter infiltration and high spring and summer runoff. Under an interglacial climate, infiltration is more significant. The probable absence of permafrost in the catchment means that a lag between the two states due to its gradual decay is unlikely. Palaeoecology, supported by radiocarbon dates, suggests that, at the very start of the Holocene, a dramatic episode of fine sediment deposition across most of the valley floor occurred, lasting 500-1000 years. A phase of peat accumulation followed as mineral sediment supply declined. A further shift led to tufa deposition, initially in small pools, then across the whole floodplain area, with the river flowing through channels cut in tufa and experiencing repeated avulsion. Major floods, leaving large gravel bars that still form positive relief features on the floodplain, followed mid-Holocene floodplain stability. Prehistoric deforestation is likely to be the cause of this flooding, inducing a major environmental shift with significantly increased surface runoff. Since the Bronze Age, predominantly fine sediments were deposited along the valley with apparently stable channels and vertical floodplain accretion associated with soil erosion and less catastrophic flooding. The Kennet demonstrates that, while a general pattern of river behaviour over time, within a region, may be identifiable, individual rivers are likely to diverge from this. Consequently, it is essential to understand catchment controls, particularly the relative significance of surface and subsurface hydrology

Are climate warming and enhanced atmospheric deposition of sulfur and nitrogen threatening tufa landscapes in Jiuzhaigou National Nature Reserve, Sichuan, China?

Massive deposition of calcium carbonate in ambient temperature waters (tufa) can form magnificent tufa landscapes, many of which are designated as protected areas. However, tufa landscapes in many areas are threatened by both local anthropogenic activities and climate change. This study, for the first time, posed the question whether the tufa landscape degradation (characterized by tufa degradation and increased biomass of green algae) in Jiuzhaigou National Nature Reserve of China is partially caused by regional air pollution and climate warming. The results indicate that wet deposition (including rain and snow) polluted by anthropogenic SO2, NOx, and NH3 emissions dissolves exposed tufa and may considerably reduce tufa deposition rate and even cause tufa dissolution within shallow waters. These effects of wet deposition on tufa enhanced as pH of wet deposition decreased from 8.01 to 5.06. Annual Volume Weighted Mean concentration of reactive nitrogen (including NH4+ and NO3-) in wet deposition (26.1 μmol L-1) was 1.8 times of the corresponding value of runoff (14.8 μmol L-1) and exceeded China's national standard of total nitrogen in runoff for nature reserves (14.3 μmol L-1), indicating a direct nitrogen fertilization effect of wet deposition on green algae. As water temperature is the major limiting factor of algal growth in Jiuzhaigou and temperature in the top layer (0-5 cm) of runoff (depth < 1 m, no canopy coverage of trees and shrubs) was significantly higher at the sites with increased biomass of green algae (p < 0.05), climate warming in this region would favor algal growth. In sum, this study suggests that climate warming and enhanced sulfur and nitrogen deposition have contributed to the current degradation of tufa landscape in Jiuzhaigou, but in order to quantify the contributions, further studies are needed, as many other anthropogenic and natural processes also influence tufa landscape evolution

Palaeoclimate changes in the Afyon province, Sw-Turkey, during the Middle-Late Pleistocene: Signals from calcareous tufa pollen and stable isotope records

The calcareous tufas of Sarikavak located in the northern part of NE-SW trending Acigöl Graben in SW-Turkey are investigated in detail. For this aim, various analyses (stable isotopes, U/Th dating, palynology) have been carried out on samples obtained from both outcrops and drilling logs in and surrounding Sarikavak Village. U/Th dating shows that these carbonates precipitated from 400 ka up to 80 ka. Preliminary pollen data, document climatic variability between MIS 11 and MIS 8 in the studied area. © 2010 AIQUA - Associazione Italiana per lo Studio del Quaternario e EMMEVI - Servizio Congressi SPA

Further expansion of the alien seaweed Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procacini (Ulvophyceae, Bryopsidales) in the Eastern Mediterranean Sea

We are grateful to Andreas Antoniou (Dep. of Environment, Ministry of Agriculture, Rural Development & Environment, Cyprus) for his assistance in the preparation of the illustrations. We would also like to thank Dr. Sotiris Orfanidis (NAGREF – Fisheries Research Institute, Kavala, Greece) for his valuable advice and both the DFMR and HSR / HCMR Rhodes crew and George Hatiris for their help in samplings. Special thanks are due to Dinos Leonidou (SeaQuest Divers Cyprus) for accompanying the deep dive for sampling Caulerpa at Cavo Greco. We are grateful to the Total Foundation (Paris) for its funding support to this study within the framework of the project “Brown algal ecology and biodiversity in the eastern Mediterranean Sea” and to the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011).Peer reviewedPublisher PD

Mg/Ca ratios in freshwater microbial carbonates: Thermodynamic, kinetic and vital effects

The ratio of magnesium to calcium (Mg/Ca) in carbonate minerals in an abiotic setting is conventionally assumed to be predominantly controlled by (Mg/Ca)solution and a temperature dependant partition coefficient. This temperature dependence suggests that both marine (e.g. foraminiferal calcite and corals) and freshwater (e.g. speleothems and surface freshwater deposits, “tufas”) carbonate deposits may be important archives of palaeotemperature data. However, there is considerable uncertainty in all these settings. In surface freshwater deposits this uncertainty is focussed on the influence of microbial biofilms. Biogenic or “vital” effects may arise from microbial metabolic activity and/or the presence of extracellular polymeric substances (EPS). This study addresses this key question for the first time, via a series of unique through-flow microcosm and agitated flask experiments where freshwater calcite was precipitated under controlled conditions. These experiments reveal there is no strong relationship between (Mg/Ca)calcite and temperature, so the assumption of thermodynamic fractionation is not viable. However, there is a pronounced influence on (Mg/Ca)calcite from precipitation rate, so that rapidly forming precipitates develop with very low magnesium content indicating kinetic control on fractionation. Calcite precipitation rate in these experiments (where the solution is only moderately supersaturated) is controlled by biofilm growth rate, but occurs even when light is excluded indicating that photosynthetic influences are not critical. Our results thus suggest the apparent kinetic fractionation arises from the electrochemical activity of EPS molecules, and are therefore likely to occur wherever these molecules occur, including stromatolites, soil and lake carbonates and (via colloidal EPS) speleothems

Pengukuran Electrical Logging pada Pemboran Air Tanah dalam di Daerah Pacciro Kecamatan Balusu Kabupaten Barru

Metode pengukuran logging geofisika merupakan salah satu metode geofisika yang biasa digunakan untuk melihat potensi penyebaran lapisan tanah atau batuan secara vertikal yang merupakan lapisan pembawa air tanah (akuifer) atau bukan lapisan pembawa air yang dilakukan setelah kegiatan pemboran. Tujuannya yaitu untuk mengetahui gambaran vertikal sekitar lubang bor dari hasil pengukuran logging geofisika. Penelitian dilakukan di daerah Pacciro Kecamatan Balusu, Kabupaten Barru. Metode logging geofisika yang digunakan yaitu metode electrical logging baik itu metode resistvitas (tahanan jenis) maupun self potential (SP). Alat yang digunakan dalam pengukuran electrical logging yaitu mini logger Naniura Model ND 112 P. Adapun data-data yang digunakan yaitu nilai tahanan jenis (resistivitas) dan nilai potensial dari material sekitar lubang bor yang hasil akhirnya menunjukkan kurva kuantitas dari nilai tahanan jenis dan potensial. Dari kurva tersebut maka dapat diinterpretasi lapisan tanah dan batuan sekitar lubang. Hasil penelitian menunjukkan pada kedalaman 0-2 m merupakan tanah penutup (top soil), kedalaman 2-11 m merupakan pasir lanauan, kedalaman 11-18 m merupakan lempung pasiran, kedalaman 18-22 m merupakan pasir lempungan, kedalaman 22-35 m merupakan lapisan tufa pasiran, kedalaman 35-39 m merupakan lapisan tufa agak halus, kedalaman 39-49 m merupakan lapisan tufa pasiran, kedalaman 49-53 m merupakan lapisan tufa kasar, kedalaman 53-61 m merupakan lapisan tufa, kedalaman 61-68 m merupakan lapisan tufa