Different Degrees Of Preservation Research Articles

Ediacaran biota from Ougnat Massif (Eastern Anti-Atlas, Morocco): Paleoenvironmental and stratigraphic constraints

The Ediacaran period records the appearance of the first multicellular and complex organisms in Earth's history. Within the West African Craton, just a few simple discoidal structures have been previously reported within the supposed Ediacaran successions. Here, we describe for the first time a slightly diversified Ediacaran assemblage of micro- and macro-fossils from Ediacaran volcano-sedimentary rocks of Northwest Africa. Fossils occur in shallow water carbonate-bearing siliciclastic sediments of the Izelf Formation (567–550 Ma), in the Moroccan Anti-Atlas. Macrofossils are represented by Aspidella, ivesheadiomorphs and other problematic structures with putative biotic origin. The macrofossil assemblage is dominated by taphomorphs that indicate different degrees of preservation due to progressive decaying processes, possibly extending the effacement preservation mode outside of Avalonia assemblages. Microbially induced sedimentary structures (MISS), stromatolites and spheroidal microfossils are also reported. In particular, spheroidal microfossils may occur as isolated individuals or as concatenated spheres with potentially cell-division processes and were preserved through carbonate and silica permineralization. Morphologically, spheroidal microfossils are compared to sphaeromorph acritarchs and sulfur-oxidizing bacteria such as genus Thiomargarita. The depositional environment and age interval provide new information concerning paleogeographic and paleoenvironmental conditions of Ediacaran biota living on the West African Craton; thus, fills a gap in the Precambrian fossil record from the WAC.

Діагностування та консекветний моніторинг стану збереження рукописних документів з Бібліотеки Наукового товариства імені Шевченка у Львові

The article analyzes the results of consistent monitoring of the state of preservation of collection of manuscripts and document sfrom the Shevchenko Scientific Society Library in Lviv, which are now stored in the V. Stefanyk LNNBU. Сonducted a comprehensive analysis of the key areas of formation of the NTSh Library fund and the results of qualimetric research in the field of preservation of its manuscript heritage. On the basis of studying the state of preservation of the manuscript fund and processing the results of qualimetric research, the analysis of the operational state of the whole collection and each specific storage unit in particular was carried out. In order to study the ecological and physical condition of the exceptionally valuable archival fund of the Library, a survey of manuscripts and documents from the fund of the Library of NTSh was performed. The safety of stock units has been studied using a modified qualimetric method, which allows you to analyze the performance of documents. The method consists in organoleptic research and assessment of physical safety of material components of manuscripts. It is established that the manuscript fund of the NTSh Library consists of documents created at different times, which are different in terms of material basis and with different degrees of preservation. Active use, the destructive effects of the environment, anthropogenic and natural factors have led to the deterioration of their condition. Qualimetric examinations of documents 14 – 18, 18-19 centuries. Fnd the data obtained during the analysis of the state of preservation of documents showed that the documents of good preservation in this part of the collection is less than 15%. More than 45% of medium-preserved documents, which require minor conservation and restoration interventions, and almost 40% of valuable manuscripts are low-preservation documents and require more complex restoration operation. The results of the study, obtained during the monitoring of the physical condition of the manuscript fund of the NTSh Library, will allow to plan and implement methods for the return of written monuments of operational properties, their further use and study by a wide range of scientists. For the first time surveys of the manuscript fund of the NTSh Library allowed to determine the necessity and priority of preventive and operative conservation and restoration measures for specific written monuments. The information obtained will help to plan and optimize the approach to the implementation of restoration processes at various sites. Keywords: NTSh library, storage, manuscripts, conservation, monitoring, qualimetry.

THE EFFECT OF CONVERGENCE ANGLE OF TOOTH PREPARATION IN PATIENTS WITH GENERAL PERIODONTITIS ACCORDING FINITE ELEMENT ANALYSIS

Purpose of the research. To study the character of displacement and stress distribution after prosthetics of the lower central incisor with the metal-ceramic crown, depending on the convergence angle of preparation and the degree of resorption of alveolar septa using finite element analysis. Research methods. The computer models have been studied using the calculated software complex “Lira 9.6” to reproduce intact (before preparation) and treated teeth, taking into account subsequent imposition of a metal-ceramic crown. Calculations have been made for different convergence angles, from 20 to the maximum possible, for four types of loads (constant from own weight; vertical from food biting off; at an angle of 300 to vertical; at an angle of 450 to vertical) and for different degrees of preservation of alveolar septa: 100 %, 75 % and 50 %. Scientific novelty. It has been established that in the calculated model the increase of the convergence angle of tooth surfaces, as well as the decrease in alveolar septa height, cause the increase in displacements in the biomechanical system “crown – tooth – alveolar bone”, the maximum of which are localized in the neck area of the tooth on its lingual surface. The increase in the angle of preparation causes the increase in stresses in the same area, while the increase in the degree of resorption of alveolar septa results with the displacement of the maximum stress zone from the tooth neck to the apical part of the root. Conclusions. The obtained results indicate the need for tooth preparation with the minimum convergence angle of surfaces in patients with general periodontitis. It could prevent the risks of the progression of the pathological process in periodontal tissues due to the increase of stresses and displacements.

THE RESTORATION OF KUFIC DIRHAMS IN THE LIGHT OF MODERN STUDIES

The article examines the restoration of Kufic dirhams from the collection of the National Museum of the History of Ukraine; it presents the interrelationship of chemical-physical, aesthetic and restorationethical components of identical exhibits and also structures the main formations of silver and copper according to their influence on the condition of the object. The problems of the background for further restoration measures of destructive processes of archaeological exhibits made of silver-based alloy are considered, and the nature of the aesthetic component of silver exhibits is outlined. Based on the analysis of modern methods of restoration of similar exhibits, the current limits of the range of approaches to solving similar problems are outlined. As a result of the study of exhibits – Kufic dirhams, ways of developing restoration methods of patination at museum restoration are revealed. The proper display appearance and, accordingly, the nature and depth of restoration treatments significantly differ all over the world. The above-mentioned issues are especially acute in the restoration of silver due to the significant contrast in the appearance of exhibits of different degrees of preservation. As a result of mineralization, the shape of the silver object is usually deformed, and the surface loses its metallic luster. It is difficult to distinguish exhibits with a significant copper content from copper ones by their appearance. The restoration approaches and conservation measures have significant differences, so they require a careful study. This study examines the processes of preliminary removal of persistent wax layering, a restoration measure rarely analyzed by researchers. Highlighting the restoration of Kufic dirhams from the collection of the National Museum of the History of Ukraine has a particular interest in working with similar exhibits and substantiating the prospects for the direction of further research.

СРБИ У ПОМОРИШЈУ: ИЗМЕЂУ СЕЛА И ГРАДА

Based on the fieldwork research of Serbs in Arad county (Romania) done in 2013– 2015, the paper analyzes narratives about personal relocation to the city of Arad and elements of biographical stories given in the form of digressions in narratives covering the themes of traditional Serbian culture. Collected material comes from the settlements of Nadjfala/Satu Mare, Felnak/Felnac, Monoštor/Mănăştur Munara/Munar, Tornja/Turnu, town of Arad, as well as from published memories of the victims of communism. The time period covered in the narratives starts from the period of communism, through the Revolution of 1989, all the way to the modern, parallel world and double life in the villages and Arad at the same time. The narratives are divided into five thematic units that cover the current situation in the settlement, memories of the Felnac tamburitza orchestra, trips to Arad from a children’s perspective, fragments about everyday life in Arad and today’s situation of emotional division between the village and the city. The attached transcripts are verbatim and reflect the different degrees of preservation of the Serbian language (Šumadija-Vojvodina dialect) and the corresponding influence of the Romanian language in each individual participant.

Morphological and compositional analyses of coprolites from the Upper Cretaceous Bauru Group reveal dietary habits of notosuchian fauna

The fluvial deposits of the Adamantina Formation (Upper Cretaceous, Bauru Group) have produced a rich fossil vertebrate record of fishes, amphibians, lizards, snakes, turtles, dinosaurs and mammals. However, the record of notosuchians (Crocodylomorpha) is remarkable in terms of both diversity and number of findings. Here, we report a large number of new coprolites found in association with skeletons of crocodylomorphs from the Adamantina Formation in the cities of Jales and Fernandópolis, São Paulo State, Brazil, and discuss their meaning for the understanding of feeding habits of their producers. The coprolites from Jales were found mostly together with adult skeletons of baurusuchids and crocodylomorph egg clutches, while the coprolites from Fernandópolis are associated with adult sphagesaurids and juvenile and adult baurusuchid skeletons, and rare crocodylomorph egg clutches. Forty-one coprolites were analysed encompassing different degrees of preservation. The X-ray diffraction showed the coprolites are comprised mainly of fluorapatite. The presence of bone fragments in some coprolites, together with their typical crocodylomorph cylindrical shape with rounded ends, strongly indicates that Baurusuchidae not only are carnivores, but that also ingested large bone fragments. On the other hand, the coprolites assigned to Sphagesauridae generally show a more complex chemical composition and present plant remains within which indicate this group, at least in part, fed on plants. Our results reinforce the importance of these ichnofossils as an independent source of information on the feeding habits of their producers and add new evidence these two groups of crocodylomorphs fed on different food sources.

Optimization of Method for Human Sex Determination Using Peptidome Analysis of Teeth Enamel from Teeth of Different Biological Generation, Archeological Age, and Degrees of Taphonomic Preservation.

Determination of biological sex to human remains is a fundamental requirement in anthropological, archeological, and forensic anthropological studies. Sex determination based on morphological criteria is significantly limited in the cases of juvenile remains and adult skeletons in a poor state of preservation. Regular attempts have been made to use alternative techniques to resolve this issue, including analysis of tooth enamel peptides by liquid chromatography/mass spectrometry. Optimization of this method involving acid etching of tooth enamel for 10 min followed by desalting of the products of etching on SDB-RPS StageTips microcolumns and analysis of desalted sample (1/3) by liquid chromatography/mass spectrometry allowed reliable sex determination to fossil remains within a wide range of archeological and biological ages without destructing analyzed teeth. Increasing the duration of enamel etching ensured a 2 to 3-fold increase in the total number of identified peptides and, more importantly, in the number of identified fragments of amelogenin Y isoform specific for male teeth, which facilitated reliable sex determination of fossil remains. The suggested technique was tested with 8 permanent and 15 deciduous teeth of different archaeological age and different degree of preservation. Two amelogenin Y-specific peptide sequences were identified. One of these peptides [SM(+15.99)IRPPYS)] was found in all male-derived samples without exception; the other peptide [IRPPYSS(+79.97)], which contained phosphorylated Ser66 residue, was found only in the enamel from deciduous teeth, which suggests that phosphorylation of Ser66 plays a role in the enamel formation in deciduous teeth.

Немецкие островные диалекты Томской и Новосибирской областей (на материале открытого онлайн-архива немецких диалектов Сибири)

The paper interprets the data from the open online archive of German dialects (https:// www.tomdeutsche.ru/dialects/). This work was started ten years ago in Tomsk by Prof. Z. M. Bogoslovskaya and her students. The archive provides the records of the native dialects and folklore of Russian Germans whose speech originates from different mother tongues and has different degrees of preservation. Archival materials were collected on the territory of Tomsk and Novosibirsk regions during linguistic expeditions of recent years. Many dialects of the upper German and middle German types appear to be mixed, containing (primarily in phonological terms) the features of different dialect systems, mixed as early as last century. These are secondary language formations that are exclusively spoken by older people. It is not the case in the German-Mennonite dialect (Plautdietsch), which is based on the Low German language substrate. This dialect has a higher degree of preservation and is spoken not only by older people but also by young people and children. The genre component of the collected samples of folklore and religious practices does not show much diversity. The archive contains only a few samples of songs, ditties, and jokes that old speakers can still perform in their native dialect. A special role is played by literary German – it is the language of liturgical practices, of prayers and spiritual singing. The paper presents a number of dialect material transcriptions.

Testing LA-ICP-MS analysis of archaeological bones with different diagenetic histories for paleodiet prospect

LA-ICP-MS is a powerful technique requiring minimal sample preparation and providing high spatial resolution which may offer the possibility of analysing trace elements in targeted pristine areas of archaeological bone sections. This would provide invaluable information about an individual's life if combined with the geochemical composition of the teeth from the same individual. However, there is no consensus regarding the calibration to be used for LA-ICP-MS analysis of bone, which is a highly complex organo-mineral tissue. In this study, we tested different calibration approaches (NIST and USGS glass series, synthetic phosphate glass and synthetic phosphate pellet from USGS) on a modern bone. The best method was applied to three Precolumbian skeletons (Lerma Valley, Mexico). These individuals show different degrees of preservation (crystallinity, calcite, F and organic matter content) which have been previously explored at the intra-skeletal level. A bone sample with exceptional preservation from the Dogon Country (Mali) was analysed for comparison.Based on BSE SEM images and element distribution of the bone sections obtained via LA-ICP-MS mapping, quantification of Ca, P, Li, Zn, V, U, Na, Mg, Sr and Ba was performed using LA-ICP-MS spot analysis on areas displaying varying concentration profiles and histological preservation. Although avoiding sampling at the external margin of the bone sections may minimize diagenetic Li, Zn, V, U, Sr and Ba, it was not possible to discriminate biological from diagenetic Sr adsorbed onto the bone crystallites of the best preserved Precolumbian skeleton, whose low crystallinity favored adsorption efficiency. In contrast, the well preserved Dogon sample, as well as the most altered Precolumbian skeletons provided Sr and Ba content roughly similar to concentrations obtained using bulk analysis. LA-ICP-MS can therefore not substitute solution analysis for paleodiet prospect, especially for bones in relatively early state of diagenetic transformations.

Influence of Deforestation on the Community Structure of Sand Flies (Diptera: Psychodidae) in Eastern Amazonia.

Variation in the structure of phlebotomine (sand fly) communities in forest fragments with different degrees of preservation and human occupation (peridomicile) in eastern Amazonia was studied. We identified 43 species of sand flies in our study, of which 38 occurred in both preserved forest areas and in the peridomiciles of short-term settlements, while another 28 species occurred in altered forest fragments and long-term settlements. The composition of the community at each site changed with the type of environment (forest or peridomicile), with the species Lutzomyia evandroi, L. whitmani, L. choti, L. serrana, L. triacantha, L. migonei, L. hirsuta, L. shannoni, and L. brachyphylla accounting for more than 54% of the differences among environments. The quality of the environment exerted a significant influence on the structure of phlebotomine communities, and affected their species composition, richness, and abundance.

Preservation and Significance of Extracellular DNA in Ferruginous Sediments from Lake Towuti, Indonesia.

Extracellular DNA is ubiquitous in soil and sediment and constitutes a dominant fraction of environmental DNA in aquatic systems. In theory, extracellular DNA is composed of genomic elements persisting at different degrees of preservation produced by processes occurring on land, in the water column and sediment. Extracellular DNA can be taken up as a nutrient source, excreted or degraded by microorganisms, or adsorbed onto mineral matrices, thus potentially preserving information from past environments. To test whether extracellular DNA records lacustrine conditions, we sequentially extracted extracellular and intracellular DNA from anoxic sediments of ferruginous Lake Towuti, Indonesia. We applied 16S rRNA gene Illumina sequencing on both fractions to discriminate exogenous from endogenous sources of extracellular DNA in the sediment. Environmental sequences exclusively found as extracellular DNA in the sediment originated from multiple sources. For instance, Actinobacteria, Verrucomicrobia, and Acidobacteria derived from soils in the catchment. Limited primary productivity in the water column resulted in few sequences of Cyanobacteria in the oxic photic zone, whereas stratification of the water body mainly led to secondary production by aerobic and anaerobic heterotrophs. Chloroflexi and Planctomycetes, the main degraders of sinking organic matter and planktonic sequences at the water-sediment interface, were preferentially preserved during the initial phase of burial. To trace endogenous sources of extracellular DNA, we used relative abundances of taxa in the intracellular DNA to define which microbial populations grow, decline or persist at low density with sediment depth. Cell lysis became an important additional source of extracellular DNA, gradually covering previous genetic assemblages as other microbial genera became more abundant with depth. The use of extracellular DNA as nutrient by active microorganisms led to selective removal of sequences with lowest GC contents. We conclude that extracellular DNA preserved in shallow lacustrine sediments reflects the initial environmental context, but is gradually modified and thereby shifts from its stratigraphic context. Discrimination of exogenous and endogenous sources of extracellular DNA allows simultaneously addressing in-lake and post-depositional processes. In deeper sediments, the accumulation of resting stages and sequences from cell lysis would require stringent extraction and specific primers if ancient DNA is targeted.

A tale of two gorges: Late Quaternary site formation and surface dynamics in the Mula basin (Murcia, Spain)

We present a case-study in Palaeolithic archaeology focusing on formation processes at cave- and rock-shelter-sites in a Mediterranean context and on the correlation between site deposits, Quaternary surface sediments and the morphology of the surrounding land. We study three sites located in the basin of River Mula (Murcia, Spain): the cave-site of Cueva Antón and the rock-shelters of Finca Doña Martina and Abrigo de la Boja, in the Rambla Perea valley. They are examined through an integrated geoarchaeological approach that takes into account geomorphological, stratigraphic and soil micromorphological data. The three sites are found within a short distance and cover similar time spans within the Upper Pleistocene but have different formations and show distinct degrees of preservation of the archaeological record. Cueva Antón features a densely-stratified, mostly alluvial succession, with excellent preservation of stratigraphic layout and sedimentary facies. The succession represents a well-preserved record of past activity of the River Mula and can be correlated to its open-air alluvial system. The Rambla Perea sites, despite their immediate vicinity, underwent distinct formation dynamics, with a complex interaction among the site deposits and the hillslope along which they are found, and exhibit different degrees of preservation of archaeological layers and features. We summarise the evidence from these sites and then discuss its implications for site formation, for the preservation of the archaeological record and for the correlation between the ‘inside’ (the archaeological successions preserved within caves and in rock-shelters) and the ‘outside’ (the geomorphological setting of the land and the evolution of Quaternary surface dynamics through time).

Germinal Center-Derived Lymphomas and Plasmacytomas in Mice with Targeted Deletion of MiR-15a/16-1 in Activated B Cells

MicroRNA (miR)-mediated gene regulation plays critical roles in B-cell development and dysregulated expression of miRs has been implicated in the pathogenesis of various types of B-cell malignancies. Somatic deletions of chromosome 13q14, harboring miR-15a/16-1, occurs frequently in B-cell lymphomas suggesting that members of this miR family are tumor suppressors. Consistently, mice with CD19-Cre-induced deletion of miR-15a/16-1 in early B-cells and follicular B-cells develop chronic lymphocytic leukemia (CLL). Since the 13q14 deletion is observed in a broader range of B-cell malignancies, we hypothesized that the type of B-cell malignancy resulting from miR-15a/16-1 down-regulation may depend on the stage of B-cell development at which this deletion occurs. Therefore, we generated a transgenic mouse model in which conditional deletion of miR-15a/16-1 takes place at later stages of B-cell development. To delete miR-15a/16-1 in activated B-cells, miR-15a/16-1fl/fl mice were mated with AID-Cre+/+ mice to obtain AID-Cre+/-; miR-15a/16-1fl/fl compound mice that expressed Cre recombinase from the Activation-induced Cytidine Deaminase (AID promoter) gene - a gene needed for generation of somatic hypermutations in the immunoglobulin (Ig) variable region (V) genes that is highly expressed in activated B-cells and is a well-known marker for germinal center (GC) B-cells. Expression levels of both miR-15a and miR-16-1, but not miR-15b were decreased in GC B-cells of AID-Cre+/-; miR-15a/16-1fl/fl mice as compared with control AID-Cre+/- mice when evaluated by In Situ Hybridization (ISH) analysis. Given that in humans miR-15a, b and 16 are also expressed in GC B-cells, these results demonstrate the validity of this mouse model in which the biological consequences of miR-15a/16-1 deletion can be studied. Next we assessed whether miR-15a/16-1 deletion could affect proliferation and/or survival of GC B-cells. GCs in the spleens of AID-Cre+/-; miR-15a/16-1fl/fl mice at 10 weeks of age were significantly increased in both number and size, and contained a larger number of Ki-67-positive B-cells as compared with spleens of AID-Cre+/- mice. No significant differences in the number of apoptotic cells, neither in the expression of the miR-15a/16-1 putative target BCL2 were detected, indicating that miR-15a/16-1 may play important roles in the proliferation, but not survival of GC B-cells. Apart from mild splenic enlargement and increased number and size of GCs, AID-Cre+/-, miR-15a/16-1fl/fl mice where indistinguishable from AID-Cre+/- mice between 8 and 40 weeks of age as assessed by weight and posture. However, after 48 weeks of age and at variable times thereafter, 80% (32/40) of AID-Cre+/-, miR-15a/16-1fl/fl mice but none from control cohorts (0/30) showed signs of disease. Gross pathologic examination of euthanized AID-Cre+/-; miR-15a/16-1fl/fl mice revealed enlargement of the spleen and lymph nodes. Detailed histological examination revealed in most instances an effacement of normal tissue architecture by a nodular or diffuse population of atypical lymphoid cells, or less commonly by sheets of plasma cells in interfollicular areas. Two distinct patterns of B220+BCL6+BCL2- B-cell lymphomas were identified after detailed analysis. The most common (47%) resembled human follicular lymphoma (FL) and the next in frequency (28%) resembled human diffuse large B-cell lymphoma (DLBCL). The other group of tumors (25%) resembled human plasmacytoma (PC). All three tumor subtypes were clonal, hypermutated and associated with different degrees of preservation of the dendritic meshwork in the lymph nodes. The comparison of lymphomas arising in AID-Cre+/-; miR-15a/16-1fl/fl mice and CD19-Cre+/-; miR-15a/16-1fl/fl mice corroborated that deletion of miR-15a/16-1 at different stages of B-cell development leads to distinct subtypes of B-cell malignancies. Finally, we investigated miR-15a/16-1 expression in human FL and PC and showed that miR-15a/16-1 abundance is significantly decreased in those malignancies when compared with nodal B-cells in reactive GCs and normal plasma cells in interfollicular areas respectively, suggesting that miR-15a/16-1 may play important roles in normal GC B-cell development as well as in the pathogenesis of FL and PC in humans. DisclosuresGhobrial:BMS: Honoraria, Research Funding; Novartis: Honoraria; Celgene: Honoraria, Research Funding; Takeda: Honoraria; Noxxon: Honoraria; Amgen: Honoraria. Anderson:Oncoprep: Equity Ownership; Acetylon: Equity Ownership; Oncoprep: Equity Ownership; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Acetylon: Equity Ownership; Millennuim: Membership on an entity's Board of Directors or advisory committees; Millennuim: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Equity Ownership; C4 Therapeutics: Equity Ownership; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees.

Systematic and taphonomic insights of fossilized feathers: A new occurrence from the Oligocene of Taubaté Basin (SE, Brazil)

Feathers are rare in the fossil record because they have a low fossilization potential. Despite their palaeobiological significance, they also provide important palaeoecological and taphonomic information. Here, we report a new occurrence of three isolated feathers from the shales of the Oligocene Tremembé Formation (Taubaté Basin, SE Brazil). Their possible taxonomic affinities and taphonomic features are also discussed. Analyses identified the specimens as representatives of two pennaceous morphotypes (i.e., a contour and a rectrice feather). Both are preserved as carbonized traces, although, due taphonomic processes, they show different degrees of preservation. Since the Tremembé Formation is responsible for the most diverse record of Cenozoic birds, and because water-adapted birds (e.g., anseriformes and phoenicopteriformes) occur in this unit, it is highly possible that these feathers belonged to these aquatic taxa. Further investigations should concentrate on geochemical and microscopic techniques in order to reveal additional taxonomic and paleoecological features currently unknown in Paleogene birds of Brazil.

Recording of climate and diagenesis through sedimentary DNA and fossil pigments at Laguna Potrok Aike, Argentina

Abstract. Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. In theory, benthic microbial community composition should depend on environmental features and geochemical conditions of surrounding sediments, as well as ontogeny of the subsurface environment as sediment degraded. In principle, DNA in sediments should be composed of ancient and extant microbial elements persisting at different degrees of preservation, although to date few studies have quantified the relative influence of each factor in regulating final composition of total sedimentary DNA assemblage. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two climatic intervals (Mid-Holocene, 5 ka BP; Last Glacial Maximum, 25 ka BP) whose sediments harbored active microbial populations were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. The genetic assemblage recovered from the Holocene record revealed a microbial community displaying metabolic complementarities that allowed prolonged degradation of organic matter to methane. The series of Archaea identified throughout the Holocene record indicated an age-related stratification of these populations brought on by environmental selection during early diagenesis. These characteristics were associated with sediments resulting from endorheic lake conditions and stable pelagic regime, high evaporative stress and concomitant high algal productivity. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. Comparison of sedimentary DNA composition with that of fossil pigments suggested that post-depositional diagenesis resulted in a rapid change in the initial nucleic acid composition and overprint of phototrophic communities by heterotrophic assemblages with preserved pigment compositions. Long DNA sequences (1400–900 bp) appeared to derive from intact bacterial cells, whereas short fragments (290–150 bp) reflected extracellular DNA accumulation in ancient sediments. We conclude that sedimentary DNA obtained from lacustrine deposits provides essential genetic information to complement paleoenvironmental indicators and trace post-depositional diagenetic processes over tens of millennia. However, it remains difficult to estimate the time lag between original deposition of lacustrine sediments and establishment of the final composition of the sedimentary DNA assemblage.

Iceberg ploughmarks on Rockall Bank, NE Atlantic

The largest icebergs delivered at present to the North Atlantic are calved primarily from fast-flowing outlet glaciers of the Greenland Ice Sheet. However, recent studies of palaeo-iceberg ploughmarks across the North Atlantic reveal multiple sources of gigantic icebergs with keels as deep as 1 km that were calved from former circum-North Atlantic ice-sheet margins, including the Greenland and Laurentide ice sheets, as well as Iceland, the Faroe Islands and Svalbard. Rockall Bank, between Europe, Greenland and North America (Fig. 1a, e), received icebergs from multiple sources during past glacial maxima, as revealed by seafloor imagery showing its extensively ploughed surface (Sacchetti et al. 2012). Fig. 1. Multibeam shaded-relief bathymetry of iceberg ploughmarks on Rockall Bank. ( a ) Ploughmarks on the southern Rockall Bank. Rose diagrams show ploughmark directions for the three sides of the bank shown. ( b ) Image from the western side of Rockall Bank. Numerous ploughmarks of variable width and length cross-cut each other and show different degrees of preservation. Sparse grounding pits are also visible. ( c ) Different types of ploughmarks are observed in the western part of Rockall Bank, from long and wide isolated furrows (up to 800 m wide) to a mix of smaller furrows with different amounts of cross-cutting. ( d ) A mix …

Structure of potamoplankton along a gradient of preservation of riparian vegetation in subtropical streams

Water quality in lotic and lentic systems is greatly influenced by the land use in the adjacent areas. This study was conducted in order to assess whether different degrees of preservation of riparian forest (from well preserved with 30m wide up to degraded with < 5 m wide) influence potamoplankton community structure. The study was conducted in three streams in the upper region of the Rio dos Sinos basin, at four sampling sites, with different width of the forest. Samplings were gathered for abiotic and biological analysis in winter (August 2010) and summer (January/February 2011). The analysis of environmental and biotic variables indicated that seasonality was the main determinant of biomass patterns, regardless of the width of riparian vegetation. The potamoplankton community of the studied streams responded to environmental conditions, although lack of significant difference among the different degrees of riparian vegetation preservation has been observed. Increasing trends on biomass, richness and diversity of species, and higher concentrations of total phosphorus and nitrogen in the non-preserved areas might indicate that the different gradients of preservation of riparian vegetation are related with the water quality in subtropical streams and consequently with the potamoplankton structure.

Study of archaeological nits/eggs of Pediculus humanus capitis by scanning electron microscopy

This paper presents and discusses archaeological samples of Pediculus humanus capitis nits/eggs in Arica, northern Chile, dating between 2000 B.C. and A.D. 500. Eight samples of nits/eggs taken directly from seven mummified bodies of both the valley and the coast of Arica, were collected and studied. Samples were analysed with scanning electron microscopy (SEM), uncoated, using low and variable pressure modes. The aim was to study the morphology of the nits/eggs, the different degrees of preservation and their research potential. All samples were in good external condition and due to manipulation before SEM analysis, the oldest ones were fractured allowing the observation in situ of the hatching ad portas of an embryo. This inside view of the egg allowed observation and identification of microstructures of the embryo such as abdominal and thoracic spiracles and claws. In the most recent and best preserved samples, external structures characteristic of the egg such as aeropyles and operculum were observed. SEM can contribute significantly to the study of ectoparasites that affected ancient American populations and in this particular case to illustrate the stages and morphology of Andean archaeological specimens of P. humanus capitis.

Scanning Electron Microscope Study of Ancient Parasite Eggs Recovered From Korean Mummies of the Joseon Dynasty

We have previously shown that parasite eggs have been identified in the coprolites of Korean mummies. These eggs have shed light on parasitic infection patterns in Korean populations living several hundred years ago. We conducted a scanning electron microscopy (SEM) study on ancient Trichuris trichiura, Ascaris lumbricoides, Metagonimus yokogawai, Paragonimus westermani, and Gymnophalloides seoi eggs recovered from Korean mummies of the Joseon Dynasty. We anticipated that the taphonomic conditions of mummification would alter the eggs of certain species but not of others. Our SEM data show that each species of ancient egg exhibited different degrees of preservation. Thus, some of them, for example, M. yokogawai, exhibited a better preservation status than others, suggesting that they should be the first candidates considered when choosing subjects for future paleoparasitological studies.

Mechanism and kinetics of pseudomorphic mineral replacement reactions: A case study of the replacement of pentlandite by violarite

Although pseudomorphic mineral replacement reactions are common in all geological environments, and have long been considered important to many geological processes such as metamorphism, metasomatism, diagenesis, and chemical weathering, their mechanisms are still not well known. We present a combined textural and kinetic study of the replacement of pentlandite, (Fe,Ni) 9S 8, by violarite (NiFe) 3S 4, and describe the mechanisms and kinetic behavior of this reaction by considering the role of the fluid phase, the causes of coupling between pentlandite dissolution and violarite precipitation, the rate-limiting steps controlling the kinetic behavior, and the origin of the length scale of the features preserved during pseudomorphism. The experiments were conducted under mild hydrothermal conditions (80–210 °C, vapor saturated pressures). Reaction kinetics shows a complex behavior depending on various physical and chemical parameters including temperature, pH, concentrations of various reaction species, solid-weight-to-fluid-volume-ratio and specific surface area. The rate of replacement (i) increases with temperature from 80 to 125 °C, then decreases as temperature further increases to 210 °C, (ii) first increases then decreases with decreasing pH from pH 6 to 1, (iii) increases with increasing concentration of oxidants such as O 2(aq), H 2O 2, and KMnO 4, but decreases with increasing concentration of Ni 2+ and Fe 3+, and with increasing solid-weight-to-fluid-volume ratio, (iv) increases linearly with the specific surface area. This kinetic behavior as well as the resulting textures revealed a coupled dissolution–reprecipitation reaction mechanism. Nanometer-scale pseudomorphic replacement, through which the crystallographic orientation of pentlandite is inherited by violarite, occurs only between 1 < pH < 6, and spatial coupling between dissolution and reprecipitation is controlled by the local solution chemistry as well as by epitaxial nucleation mediated by the pentlandite substrate. The kinetic results show that pentlandite dissolution is rate-limiting under mild acidic to neutral conditions (1 < pH < 6), while violarite precipitation is rate-limiting under strong acidic conditions (pH 1). The difference in rate-limiting steps influences the coupling mechanism and causes the different degrees of preservation (length scale of pseudomorphism) and different morphologies observed at high and low pHs: pentlandite dissolution being rate-limiting results in nanoscale coupling between dissolution and precipitation and thus nanoscale pseudomorphism (length scale <20 nm), in which the replacement precisely preserves the morphology and internal details, resembling remarkably the natural pentlandite/violarite assemblages. In contrast, violarite precipitation being rate-limiting results in microscale pseudomorphism (length scale ∼10 μm): the morphology of the pentlandite grains is only roughly preserved and internal details are not preserved. This case study illustrates some general principles of replacement reactions proceeding via the coupled dissolution–reprecipitation mechanism: (i) primary mineral dissolution needs to be rate-limiting compared to the secondary mineral precipitation in order to achieve a high degree pseudomorphic replacement; (ii) the effects of solution composition on reaction kinetics can be qualitatively rationalized by considering the rate-limiting step reaction.