Prehistoric and Recent Land Use Effects on Poike Peninsula, Easter Island (Rapa Nui)

Since the first Polynesian settlers set foot on Rapa Nui, probably between AD 300 and AD 600, cultivation of plants and the development and adaptation of agriculture in the new environment became the key factor for a growing community and a flourishing culture. The biotic resources the people found on Rapa Nui were relatively poor due to the lack of diversity of edible and usable plants and animals, a consequence of its isolation in the Pacific Ocean. The people depended on the supplies they carried with them in their canoes as they did for hundreds of years while exploring the solitary Polynesian islands. And they depended of course on the abiotic resources as these set the limits for cultivation of plants and fruits. Key factors in this point of view were the availability of water and the fertility of the soils for growing plants, suitable climatic factor for the species cultivated, geomorphologic conditions that would allow farming and the availability of area for land use in relation to the population size.</p

The monumental landscape transformation of the Island of Babeldaob (Republic of Palau)

Babeldaob is the largest island of Palau. The landscape of this mostly volcanic island is dominated by monumental earthworks, like terraced hills, crown and moat constructions, and modified ridgelines. The majority of the Palau earthworks were built between 2400 and 1200 BP, making them the oldest examples of monumentality in Oceania according to the current state of research. Despite the degree of landscape transformation on Babeldaob, the monumental aspect of the earthworks, and the fact that oral traditions are of utmost importance in the Palauan society, little information about the construction, the function, and significance of them has been passed down. Notwithstanding several archaeological investigations in the last years, questions about the chronology, genesis, function, and use of the earthworks are still open. Did the terraces serve as settlement areas? Have they been used for horticulture? Did they have a ritual or political significance? Or were they used for defence? Using aerial photogrammetry, we generated 3D-models of 14 earthworks that served as a basis for placing test trenches to investigate the construction methods and function of the monuments. Detailed geoarchaeological, geomorphological, pedological, and sedimentological analysis showed many aspects of building techniques, ancient land use, and the high stability of the earthworks

CONNECTING GEOLOGY AND GEOPHYSICS: THE GEODYNAMIC EVOLUTION OF DRONNING MAUD LAND FROM RODINIA TO GONDWANA

East Antarctica consists of a number of cratonic fragments that amalgamated along distinct orogenic belts in late Neoproterozoic to early Palaeozoic times. These mobile belts include the c. 640 to 500 Ma old East African-Antarctic Orogen (EAAO) and the Kuunga Orogen, which seem to converge in Dronning Maud Land in the Atlantic sector of Antarctica. The polymetamorphic basement of Dronning Maud Land is characterized by rocks with Grenville-age protolith ages of c. 1130 to 1000 Ma in the west and rocks with early Neoproterozoic protolith ages of c. 1000 to 900 Ma in the east. These two provinces are separated by the prominent Forster Magnetic Anomaly, which is therefore interpreted to represent a suture zone. Four joint AWI-BGR international expeditions within the WEGAS (West-East Gondwana Amalgamation and Separation) and GEA (Geodynamic Evolution of East Antarctica) programmes between 2010 and 2015 have provided new combined geological and geophysical data that reveal a complex crustal architecture between central Dronning Maud Land and Lützow-Holm-Bay. The magnetic anomaly pattern changes significantly east of the Forster Magnetic Anomaly with apparently no indication of Maud-type crust. Particularly, the GEA II campaign (2011-12) targeted a series of previously unvisited nunataks in the largely ice- covered Borchgrevink-Isen between central Dronning Maud Land and Sør Rondane from Urna and Sørsteinen in the west to Blåklettane and Bergekongen in the east. This region is characterized by NW-SE trending distinct linear magnetic anomalies. This pattern is referred to as the SE Dronning Maud Land Province and was previously interpreted as a fragment of potentially older cratonic crust south of an Ediacaran to Cambrian mobile belt that crops out in Sør Rondane. New SHRIMP/SIMS U-Pb zircon ages and geochemical analyses, however, indicate that this region consists of Rayner-age (c. 1000 to 900 Ma) juvenile arc and metasedimentary cover rocks, which were intensely reworked by medium- to high-grade metamorphism and felsic melt injections between c. 630 and 520 Ma. The juvenile rocks are very similar to a gabbro-tonalite-trondhjemite-granodiorite (GTTG) suite in the southern SW Terrane of Sør Rondane, which yield crystallization ages of c. 1000 to 920 Ma based on U-Pb zircon geochronology. The juvenile character of this suite suggests a long-lived accretionary setting in early Neoproterozoic times. While the rocks in the Borchgrevink-Isen further west were intensely reworked in Pan-African times, the GTTG complex in Sør Rondane shows evidence of Pan-African up to lower amphibolite-facies thermal overprint, but still contains large domains with apparently only weak deformation. An exception is the northern margin of the GTTG complex where high-strain dextral shear is related to the prominent Main Shear Zone that is estimated to be of latest Ediacaran to early Cambrian age (c. 560 to 530 Ma). This structure, which we interpret as part of a fault system related to NE-directed lateral extrusion of the EAAO, separates the Rayner-age GTTG complex from a series of greenschist- to granulite-facies metasupracrustal rocks of mainly volcano-sedimentary origin. They in turn are separated from the amphibolite- to granulite-facies NE Terrane in the north and north-east by the Main Tectonic Boundary that is postulated by researches of the Japanese National Antarctic Programme. Available literature and our own new geochronological data indicate that peak and retrograde metamorphism in the NE and SW terranes was at c. 640 to 530 Ma. Both terranes were intruded by several granitoid magmatic pulses between c. 650 and 500 Ma. In contrast to “Indo-Antarctic” affinities of the GTTG complex south of the Main Shear Zone and the similar rocks of the SE Dronning Maud Land Province to the west, these units thus appear to have rather “East African” affinities. Furthermore, grey heterogeneous gneisses and augen-gneisses of the aforementioned meta-volcanosedimentary supracrustal rocks of the SW Terrane close to the Main Shear Zone gave zircon crystallization ages of c. 750 Ma. Such ages are unknown from the EAAO in central and western Dronning Maud Land west of the Forster Magnetic Anomaly. Taking all evidence together, we propose that the Forster Magnetic Anomaly separates distinctly different parts of the EAAO. These are (i) a reworked, mainly Grenville-age crust of the Maud Belt to the west representing the overprinted margin of the Kalahari Craton, and (ii) a part of the orogen dominated by early Neoproterozoic accretionary tectonics to the east, which we refer to as Tonian Ocean Arc Super Terrane (TOAST). The contrast between these two crustal units is also reflected in the geochemistry of voluminous late-tectonic granitoids across the whole belt. Based on our new geological and aerogeophysical evidence, the regional crustal structure of eastern Dronning Maud Land as a whole may tentatively be interpreted as reflecting large-scale lateral extrusion of the EAAO post-dating continental collision in the late Neoproterozoic and early Cambrian

Human alveolar progenitors generate dual lineage bronchioalveolar organoids

Mechanisms of epithelial renewal in the alveolar compartment remain incompletely understood. To this end, we aimed to characterize alveolar progenitors. Single-cell RNA-sequencing (scRNA-seq) analysis of the HTII-280+/EpCAM+ population from adult human lung revealed subclusters enriched for adult stem cell signature (ASCS) genes. We found that alveolar progenitors in organoid culture in vitro show phenotypic lineage plasticity as they can yield alveolar or bronchial cell-type progeny. The direction of the differentiation is dependent on the presence of the GSK-3β inhibitor, CHIR99021. By RNA-seq profiling of GSK-3β knockdown organoids we identified additional candidate target genes of the inhibitor, among others FOXM1 and EGF. This gives evidence of Wnt pathway independent regulatory mechanisms of alveolar specification. Following influenza A virus (IAV) infection organoids showed a similar response as lung tissue explants which confirms their suitability for studies of sequelae of pathogen-host interaction

Pneumolysin induced mitochondrial dysfunction leads to release of mitochondrial DNA

Abstract Streptococcus pneumoniae (S.pn.) is the most common bacterial pathogen causing community acquired pneumonia. The pore-forming toxin pneumolysin (PLY) is the major virulence factor of S.pn. and supposed to affect alveolar epithelial cells thereby activating the immune system by liberation of danger-associated molecular patterns (DAMP). To test this hypothesis, we established a novel live-cell imaging based assay to analyse mitochondrial function and associated release of mitochondrial DNA (mtDNA) as DAMP in real-time. We first revealed that bacterially released PLY caused significant changes of the cellular ATP homeostasis and led to morphologic alterations of mitochondria in human alveolar epithelial cells in vitro and, by use of spectral live-tissue imaging, in human alveoli. This was accompanied by strong mitochondrial calcium influx and loss of mitochondrial membrane potential resulting in opening of the mitochondrial permeability transition pore and mtDNA release without activation of intrinsic apoptosis. Moreover, our data indicate cellular mtDNA liberation via microvesicles, which may contribute to S.pn. related pro-inflammatory immune activation in the human alveolar compartment

Diminution and Degradation of Environmental Resources by Prehistoric Land Use on Poike Peninsula

Interactions between ancient environmental conditions, natural resources, prehistoric land use and culture on Rapa Nui have been much discussed since Bahn and Flenley published Easter Island - Earth Island in 1992. Investigations on prehistoric agriculture on Rapa Nui were intensified in the last decade (Stevenson and Haoa 1998; Stevenson et al. 1999, 2002; Wozniak 1999, 2001). The relationships between environmental resources, land use and the cultural development on Rapa Nui were recently summarized and discussed by Martinsson-Wallin (2002). Despite intensive research on Rapa Nui's prehistory, from a scientific point of view, "forgotten" areas on the island remain, for example Poike peninsula. It was commonly believed that Poike peninsula, as the oldest part of Rapa Nui, did not have importance for agriculture. Recent research by Mieth et al. (2002) in eastern Poike showed evidence of intensive agriculture and settlement in this area. Furthermore it was proved that in eastern Poike, at around AD 1280, a dramatic change of the ecosystem took place, accompanied by the expansion of agriculture. An ancient Jubaea palm forest was cleared within a short period of time with the aim to open the landscape in the downslope areas for new ceremonial places, dwellings and agriculture.</p

The Key Role of Jubaea Palm Trees in the History of Rapa Nui

This paper presents an estimate of the number of Jubaea palm trees on Rapa Nui prior to the last clearance of the palm forest: more than 16 million palm trees. The labor requirements for clearance were enormous (a few hundred people were probably employed in this task for six to eight centuries), as well a the acquired amount of wood and the potential volume of the palm's sap (approx. 1,600,000 liter per year?). Possible uses of the palm's sap are discussed.</p

Catastrophe on an Enchanted Island

The Humboldt Current fIrst runs toward the equator parallel to the South American Pacific coast and then, near the equator, it is driven westwards to the Galapagos Islands. These waters possibly bring about the highest biological productivity on earth. The current around the Galapagos Islands became known as "La Nina".</p