Asynchrone Replikation geprägter und nicht geprägter Chromosomenregionen und Expression relevanter Entwicklungsgene in Präimplantationsembryonen der Maus

Zum besseren Verständnis der epigenetischen Reprogrammierung nach der Befruchtung, wurde in der vorliegenden Studie unter Verwendung eines Interphase-FISH-Assays eine systematische Analyse des Replikationsverhaltens geprägter und nicht geprägter Chromosomenregionen in Präimplantationsembryonen der Maus durchgeführt. Dabei konnte erstmalig gezeigt werden, dass sowohl geprägte als auch nicht geprägte Chromosomen-regionen direkt nach der Befruchtung asynchron replizieren. Vier von fünf nicht geprägten Chromosomenregionen replizierten erst nach dem Zweizell-Embryostadium synchron. Eine asynchrone Replikation geprägter Regionen wurde während der gesamten Präimplantationsentwicklung und in differenzierten Zellen beobachtet. In Morula-Embryonen zeigten der in diesem Stadium nicht exprimierte Dlk1-Gtl2-Locus sowie der biallelisch exprimierte Igf2r-Locus jedoch eine Relaxation der asynchronen Replikation. In einem weiteren Projekt konnte mit Hilfe eines Multiplex-RT-PCR-Ansatzes die sensitive Detektion von multiplen Transkripten in einzelnen Zellen etabliert werden. Anschließend wurden Expressionsmuster von 17 für die epigenetische Reprogrammierung relevanten Entwicklungs-genen in Präimplantationsembryonen sowie in einzelnen Morula-Blastomeren analysiert. Der Transkriptionsfaktor Pou5f1 wurde in allen Präimplantationsembryonen und allen Morula-Blastomeren detektiert, was auf eine uniforme Reaktivierung der Pluripotenz hinweist. Dagegen variierte die mRNA-Expression verschiedener DNA-Cytosin-5-Methyltransferasen, 5-methyl-CpG-Bindeproteine sowie Enzyme der Basenexzisionsreparatur stark zwischen individuellen Zellen des gleichen Embryos und noch stärker zwischen Zellen verschiedener Embryonen. Diese Ergebnisse zeigen, dass sich das für die Reprogrammierungsmaschinerie kodierende Transkriptom zu bestimmten Entwicklungs-zeitpunkten zwischen einzelnen Blastomeren unterscheidet.

Comparative analysis of midline guidance and axon pathfinding in the chelicerates Achaearanea tepidariorum and Cupiennius salei

Die Neurogenese und axonale Wegfindung sind in den vergangenen Jahrzehnten Thema einer Vielzahl wissenschaftlicher Untersuchungen in den verschiedensten Organismen gewesen. Die zusammengetragenen Daten in Insekten und Crustaceen geben eine gute Übersicht darüber, wie das Nervensystem in Arthropoden aufgebaut wird. Die entwicklungsbiologischen Prozesse, die daran beteiligt sind, sind in den beiden genannten Gruppen sehr gut verstanden. In den Gruppen der Cheliceraten und Myriapoden jedoch wurden ähnliche Analysen bisher kaum durchgeführt. Das Hauptanliegen dieser Arbeit war es daher, Mechanismen in den Spinnen Achaearanea tepidariorum und Cupiennius salei, zwei Vertretern der Cheliceraten, zu untersuchen, die eine Rolle im Leitsystem der ventralen Mittellinie und bei der axonalen Wegfindung spielen. Eine Vorraussetzung hierfür sind Kenntnisse über die Architektur des Zentralnervensystems. In einem ersten Schritt beschrieb ich daher grundlegend die Morphologie des Nervensystems im Verlauf der gesamten Embryoalentwicklung. Ich konnte zeigen, dass in Spinnen ein für Arthropoden typisches Strickleiternervensystem gebildet wird. Dieses wird von segmental angelegten Neuronen geformt, wobei sowohl Gruppen von Zellen als auch einzelne Neurone daran beteiligt sind, die primären axonalen Trakte zu etablieren. Im Besonderen konnte ich eine Zelle identifizieren, die in Position, Projektionsmuster und der Expression des Markergens even-skipped vergleichbar zum PR2 Neuron in Drosophila ist, welches die posteriore Wurzel des Segmentalnervs anlegt.rnrnIn einem zweiten Ansatz untersuchte ich die ventrale Mittellinie in Spinnen im Bezug auf ihre mögliche Funktion in der axonalen Wegfindung. Es konnte gezeigt werden, dass es sich beim Epithel der Mittellinie, das die Lücke zwischen beiden Keimstreifhälften während des gesamten Prozesses der Inversion überspannt, um eine transiente Struktur handelt, die keine neuralen Zellen hervorbringt. Es ist daher vergleichbar mit der so genannten Floor plate in Vertebraten, die ebenfalls nur vorübergehend existiert. Die Untersuchung von single minded (sim) zeigte, dass es, anders als in Drosophila, wo sim ein wichtiges regulatorisches Gen für die korrekte Spezifizierung von Mittellinienzellen ist, nicht in den Zellen der Mittellinie, sondern in diesen benachbarten Zellen, exprimiert wird. Das ist vergleichbar mit Vertebraten. Zusätzlich konnte ich Expression von sim an den Basen der Gliedmassen und im Kopf nachweisen. Wie in Vertebraten könnte sim an der Musterbildung dieser Gewebe beteiligt sein. Dennoch spielt die Mittellinie in Spinnen eine wichtige Rolle als Organisator für auswachsende, kommissurale Axone. Diese Funktion teilt sie mit anderen Invertebraten und Vertebraten.rnrnDie Signaltransduktionskaskade, die an der axonalen Wegfindung an der Mittellinie beteiligt ist, ist in den verschiedensten Organismen hoch konserviert. In der vorliegenden Arbeit konnte ich sowohl in Achaearanea als auch in Cupiennius ein netrin Homolog identifizieren und eine konservierte Funktion des Wegfindungsmoleküls während der Bildung der Kommissuren aufzeigen. RNAi Experimente belegen, dass, wird die Funktion von netrin herunterreguliert, das Strickleiternervensystem nicht korrekt gebildet wird, ins Besondere die kommissuralen Faszikel. Des Weiteren konnte ich eine neue Funktion von netrin, die bisher in anderen Organsimen noch nicht beschrieben wurde, identifizieren. Neben seiner Rolle in der axonalen Wegfindung, scheint netrin auch an der epithelialen Morphogenese im zentralen Nervensystem beteiligt zu sein. In dieser Funktion scheint netrin in Gliazellen, die die epithelialen Vesikel der Invaginationsgruppen umhüllen, wichtig zu sein, um neurale Vorläuferzellen in einem undifferenzierten Zustand zu halten. Der Abbau von netrin Transkript durch RNA Interferenz führt zu einer verfrühten Segregation neuraler Vorläuferzellen aus dem epithelialen Verband der Invaginationsgruppen und zu einer Zunahme an Zellen, die den frühen Differenzierungsmarker islet exprimieren.

Role of Magnesium and its mitochondrial transporter MRS2 in the modulation of drug-induced apoptosis leading to multidrug resistance phenotype

Magnesium is an essential element for many biological processes crucial for cell life and proliferation. Growing evidences point out a role for this cation in the apoptotic process and in developing multi drug resistance (MDR) phenotype. The first part of this study aimed to highlight the involvement of the mitochondrial magnesium channel MRS2 in modulating drug-induced apoptosis. We generated an appropriate transgenic cellular system to regulate expression of MRS2 protein. The cells were then exposed to two different apoptotic agents commonly used in chemotherapy. The obtained results showed that cells overexpressing MRS2 channel are less responsiveness to pharmacological insults, looking more resistant to the induced apoptosis. Moreover, in normal condition, MRS2 overexpression induces higher magnesium uptake into isolated mitochondria respect to control cells correlating with an increment of total intracellular magnesium concentration. In the second part of this research we investigated whether magnesium intracellular content and compartmentalization could be used as a signature to discriminate MDR tumour cells from their sensitive counterparts. As MDR model we choose colon carcinoma cell line sensitive and resistant to doxorubicin. We exploited a standard-less approach providing a complete characterization of whole single-cells by combining X-Ray Fluorescence Microscopy , Atomic Force Microscopy and Scanning Transmission X-ray Microscopy. This method allows the quantification of the intracellular spatial distribution and total concentration of magnesium in whole dehydrated cells. The measurements, carried out in 27 single cells, revealed a different magnesium pattern for both concentration and distribution of the element in the two cellular strains. These results were then confirmed by quantifying the total amount of intracellular magnesium in a large populations of cells by using DCHQ5 probe and traditional fluorimetric technique.

Local strain distribution in real three-dimensional alveolar geometries

Mechanical ventilation is not only a life saving treatment but can also cause negative side effects. One of the main complications is inflammation caused by overstretching of the alveolar tissue. Previously, studies investigated either global strains or looked into which states lead to inflammatory reactions in cell cultures. However, the connection between the global deformation, of a tissue strip or the whole organ, and the strains reaching the single cells lining the alveolar walls is unknown and respective studies are still missing. The main reason for this is most likely the complex, sponge-like alveolar geometry, whose three-dimensional details have been unknown until recently. Utilizing synchrotron-based X-ray tomographic microscopy, we were able to generate real and detailed three-dimensional alveolar geometries on which we have performed finite-element simulations. This allowed us to determine, for the first time, a three-dimensional strain state within the alveolar wall. Briefly, precision-cut lung slices, prepared from isolated rat lungs, were scanned and segmented to provide a three-dimensional geometry. This was then discretized using newly developed tetrahedral elements. The main conclusions of this study are that the local strain in the alveolar wall can reach a multiple of the value of the global strain, for our simulations up to four times as high and that thin structures obviously cause hotspots that are especially at risk of overstretching.

Role of intra- and peritumoral budding in the interdisciplinary management of rectal cancer patients

The presence of tumor budding (TuB) at the invasive front of rectal cancers is a valuable indicator of tumor aggressiveness. Tumor buds, typically identified as single cells or small tumor cell clusters detached from the main tumor body, are characterized by loss of cell adhesion, increased migratory, and invasion potential and have been referred to as malignant stem cells. The adverse clinical outcome of patients with a high-grade TuB phenotype has consistently been demonstrated. TuB is a category IIB prognostic factor; it has yet to be investigated in the prospective setting. The value of TuB in oncological and pathological practice goes beyond its use as a simple histomorphological marker of tumor aggressiveness. In this paper, we outline three situations in which the assessment of TuB may have direct implications on treatment within the multidisciplinary management of patients with rectal cancer: (a) patients with TNM stage II (i.e., T3/T4, N0) disease potentially benefitting from adjuvant therapy, (b) patients with early submucosally invasive (T1, sm1-sm3) carcinomas at a high risk of nodal positivity and (c) the role of intratumoral budding assessed in preoperative biopsies as a marker for lymph node and distant metastasis thus potentially aiding the identification of patients suitable for neoadjuvant therapy.

Epidermal caspase-3 cleavage associated with interferon-gamma-expressing lymphocytes in acute atopic dermatitis lesions

Keratinocyte apoptosis mediated by Fas/Fas ligand molecular interactions and subsequent caspase activation is believed to play an important role in the pathogenesis of atopic dermatitis (AD), in particular for the formation of spongiosis. To estimate epidermal caspase activation in normal and AD skin under in vivo conditions, we analysed caspase-3 cleavage by immunohistology. In normal skin as well as non-lesional AD skin, we detected caspase-3 cleavage in single cells of the basal layer. In contrast, in acute lesional AD skin, we not only obtained evidence for increased expression of cleaved caspase-3 in keratinocytes of the basal layer but also observed caspase-3 cleavage in one or more layers of the spinous cell layer, in particular in spongiotic areas. Short-term topical treatment of the skin lesions with tacrolimus or pimecrolimus abolished the expression of cleaved caspase-3 in the spinous layer. Moreover, epidermal caspase-3 cleavage correlated with the numbers of dermal interferon-gamma (IFN-gamma)-expressing CD4+ and CD8+ lymphocytes in skin lesions of AD patients, supporting the view that IFN-gamma is important for the activation of proapoptotic pathways in keratinocytes. This is also confirmed by the observation of increased Fas expression on keratinocytes in acute AD lesions that was markedly reduced following topical calcineurin inhibitor treatment. These data suggest that caspase-3 cleavage in the spinous layer of the epidermis is a pathologic event contributing to spongiosis formation in AD, whereas cleavage of caspase-3 in basal cells might represent a physiologic mechanism within the process of epidermal renewal.

Visualization and quantitative analysis of nanoparticles in the respiratory tract by transmission electron microscopy

ABSTRACT: Nanotechnology in its widest sense seeks to exploit the special biophysical and chemical properties of materials at the nanoscale. While the potential technological, diagnostic or therapeutic applications are promising there is a growing body of evidence that the special technological features of nanoparticulate material are associated with biological effects formerly not attributed to the same materials at a larger particle scale. Therefore, studies that address the potential hazards of nanoparticles on biological systems including human health are required. Due to its large surface area the lung is one of the major sites of interaction with inhaled nanoparticles. One of the great challenges of studying particle-lung interactions is the microscopic visualization of nanoparticles within tissues or single cells both in vivo and in vitro. Once a certain type of nanoparticle can be identified unambiguously using microscopic methods it is desirable to quantify the particle distribution within a cell, an organ or the whole organism. Transmission electron microscopy provides an ideal tool to perform qualitative and quantitative analyses of particle-related structural changes of the respiratory tract, to reveal the localization of nanoparticles within tissues and cells and to investigate the 3D nature of nanoparticle-lung interactions.This article provides information on the applicability, advantages and disadvantages of electron microscopic preparation techniques and several advanced transmission electron microscopic methods including conventional, immuno and energy-filtered electron microscopy as well as electron tomography for the visualization of both model nanoparticles (e.g. polystyrene) and technologically relevant nanoparticles (e.g. titanium dioxide). Furthermore, we highlight possibilities to combine light and electron microscopic techniques in a correlative approach. Finally, we demonstrate a formal quantitative, i.e. stereological approach to analyze the distributions of nanoparticles in tissues and cells.This comprehensive article aims to provide a basis for scientists in nanoparticle research to integrate electron microscopic analyses into their study design and to select the appropriate microscopic strategy.

Follicle-forming cat thyroid cell lines synthesizing extracellular matrix and basal membrane components: a new tool for the study of thyroidal morphogenesis

Interactions between follicular epithelial cells and extracellular matrix (ECM) are supposed to play an important role in the development and maintenance of thyroid tissue architecture. In the present study we have therefore investigated the synthesis of ECM components by a feline thyroid cell line which is able to form follicle-like structures in vitro, and also in v-ras-transfected and control-transfected sublines. Transfections were performed by lipofection with pZSR (viral Harvey ras gene; neo) and pSV2-neo (control, neo only) plasmids. We have adapted a semisolid culture system composed exclusively of polymerized alginate and therefore devoid of ECM components. Feline cells embedded in alginate gels as single cells and cultured for up to 90 days formed cell clusters within 10 days. Follicle-like structures were formed in the original cell lines and also in the v-ras- and control-transfected cells. Differences in proliferation rates were observed, the v-ras-transfected cells growing up to two to three times faster than the non-transfected cells. Immunostaining was done using rabbit first antibodies directed against mouse collagen IV, human fibronectin, laminin (tumor Engelbreth-Holm-Swarm laminin), perlecan and other ECM components. For comparison, immunostaining was also performed on cryosections of nodular goiters of six hyperthyroid cats. The cell lines and their transfected clones stained strongly positive for collagen IV and fibronectin, and positively but less strongly for laminin and perlecan. The cat goiter tissue stained positively for collagen IV, laminin, perlecan, and fibronectin, and positive staining for S-laminin (containing the beta2-chain) was seen in blood vessel walls in this tissue. In conclusion, cat cell lines grow three-dimensionally in alginate beads over several weeks, they form follicle-like structures and express the same ECM components as the native cat goiter tissue. Transfection with v-ras does increase proliferation rate, but does not fundamentally alter formation of follicle-like structures and ECM expression. Alginate gel culture is a promising new tool for the study of follicular morphogenesis, polarity, the expression pattern of ECM components and of the interaction between thyrocytes and ECM. It avoids interference caused by gels composed of ECM components.

Melan-a-positive "pseudomelanocytic nests": a pitfall in the histopathologic and immunohistochemical diagnosis of pigmented lesions on sun-damaged skin

We encountered recently 3 cases with a histopathologic diagnosis of melanoma in situ on sun-damaged skin (male = 2, female = 1; median age: 59 years; range: 52-60 years). The diagnosis was based mainly on the finding of actinic elastosis in the dermis and increased number of melanocytes in the epidermis and was confirmed by strong positivity for Melan-A in single cells and in small nests ("pseudomelanocytic nests"), located at the dermoepidermal junction. Indeed, examination of slides stained with hematoxylin and eosin revealed the presence of marked hyperpigmentation and small nests of partially pigmented cells at the dermoepidermal junction, positive for Melan-A. The histologic and especially the immunohistochemical features were indistinguishable from those of melanoma in situ on chronic sun-damaged skin. In addition, a variably dense lichenoid inflammation was present. Clinicopathologic correlation, however, showed, in all patients, the presence of a lichenoid dermatitis (phototoxic reaction, 1 case; lichen planus pigmentosus, 1 case; and pigmented lichenoid keratosis, 1 case). Our cases clearly show the histopathologic pitfalls represented by lichenoid reactions on chronic sun-damaged skin. Immunohistochemical investigations, especially if performed with Melan-A alone, may lead to confusing and potentially disastrous results. The unexpected staining pattern of Melan-A in cases like ours raises concern about the utility of this antibody in the setting of a lichenoid tissue reaction on chronic sun-damaged skin. It should be underlined that pigmented lesions represent a paradigmatic example of how immunohistochemical results should be interpreted carefully and always in conjunction with histologic and clinical features.

Biochemical Engineering Symposium Proceedings (June 4, 1971)

This report presents the proceedings of the Biochemical Engineering Symposium held at Kansas State University, June 4, 1971. Since most of the papers will be published elsewhere, only very brief papers are included here. Moreover, several of the projects are still in progress at this time. Request for additional information on projects conducted at the University of Nebraska should be directed to Dr. Peter J. Reilly and for Kansas State University to Dr. L. E. Erickson. ContentsChao, Chih-Cheng, University of Nebraska, "Symbiotic Growth of Actobacter suboxydans and Saccharomyces carlsbergensis in a Chemostat" S.Y. Chiu, Kansas State University, "Model Identification in Mixed Populations Using Continuous Culture Data" Shinji Goto, University of Nebraska, "Symbiotic Growth of Bacteria and Blue Green Algae in a Chemostat" I.C. Kao, Kansas State University, "ATP as a Parameter of Mixed Culture Interaction" Indravadan R. Kothari, University of Nebraska, "Growth of Single Cells of Schizocaccharomyces pombe under Nutrient Limitation" G.C.Y. Chu, Kansas State University, "Experimental Optimization of Biological Waste Treatment Processes" Mark Young, University of Nebraska, "Aerobic Fermentation of Paunch Liquor" P.S. Shah, Kansas State University, "Optimal Control of Growth Processes"

Behavioral and cellular analysis of classical conditioning of feeding behavior in Aplysia

In classical conditioning, an associative form of learning, animals learn to associate two stimuli. Cellular and molecular mechanisms for the induction and consolidation of associative learning and memory at the level of single cells and synaptic connections have been studied in both vertebrate and invertebrate animals. The majority of studies, however, relied on aversive stimuli to induce learning. This bias may limit the extent to which identified mechanisms generalize to other forms of associative learning and memory, such as appetitive forms. The goal of the present study was to develop a classical conditioning procedure for the marine mollusk Aplysia californica using appetitive reinforcement, and to analyze associative learning using behavioral and electrophysiological techniques. ^ Using tactile stimulation of the lips as the conditional stimulus (CS) and food as the unconditional stimulus (US) a training protocol was developed that reliably induced classical conditioning of feeding behavior. Memory persisted for at least 24 hours. The gross organization of reinforcement-mediating pathways was analyzed in additional behavioral experiments. Moreover, neurophysiological correlates of classical conditioning were identified and characterized in an in vitro preparation containing the circuitry for feeding behavior. In vitro stimulation of a nerve (AT4) that may mediate the CS during training, resulted in a greater number of buccal motor patterns (BMPs) in brains from conditioned animals, as compared to control animals. The majority of these BMPs were ingestion-like, consistent with the increased number of bites in response to the CS after classical conditioning. Moreover, classical conditioning correlated with increased excitatory synaptic input to BMP-initiating neuron B31/32, in response to stimulation of AT 4, as compared to controls. The expression of the correlates of classical conditioning identified in this study was specific to stimulation of AT 4, which is consistent the stimulus specificity that is characteristic for classical conditioning. ^ The identification of cellular correlates of classical conditioning documented here provides the basis for future, more detailed analyses of an appetitive form of associative learning and memory, that may extend the working knowledge of the cellular and molecular mechanisms for associative plasticity in general. ^

Abundance of phytoplankton, heterotrophic nanoflagellates and bacteria through the water column at time series station L4 in the Western English Channel. 2007-2011

The marine laboratories in Plymouth have sampled at two principle sites in the Western English Channel for over a century in open-shelf (station E1; 50° 02'N, 4° 22'W) and coastal (station L4; 50° 15'N, 4° 13'W) waters. These stations are seasonally stratified from late-April until September, and the variable biological response is regulated by subtle variations in temperature, light, nutrients and meteorology. Station L4 is characterized by summer nutrient depletion, although intense summer precipitation, increasing riverine input to the system, results in pulses of increased nitrate concentration and surface freshening. The winter nutrient concentrations at E1 are consistent with an open-shelf site. Both stations have a spring and autumn phytoplankton bloom; at station E1, the autumn bloom tends to dominate in terms of chlorophyll concentration. The last two decades have seen a warming of around 0.6°C per decade, and this is superimposed on several periods of warming and cooling over the past century. In general, over the Western English Channel domain, the end of the 20th century was around 0.5°C warmer than the first half of the century. The warming magnitude and trend is consistent with other stations across the north-west European Shelf and occurred during a period of reduced wind stress and increased levels of insolation (+20%); these are both correlated with the larger scale climatic forcing of the North Atlantic Oscillation.

Mats of psychrophilic thiotrophic bacteria associated with cold seeps of the Barents Sea

This study focused on the bacterial diversity associated with microbial mats of deep-sea cold seeps at the Norwegian continental margin. Study sites included the Storegga and Nyegga areas as well as the Håkon Mosby mud volcano, where the mats occurred at temperatures permanently close to the freezing point of seawater. Two visually different mat types, i.e. small gray mats and extensive white mats, were studied with the aim to determine the identity of the mat-forming sulfide oxidizers, and to investigate which environmental factors (e.g. sulfate reduction and methane oxidation rates) shown here could explain the observed diversity. Sequence data have been submitted to the EMBL database under accession No. FR847864-FR847887 (giant sulfur bacteria), No. FR827864 (Menez Gwen filament; see Supplementary Material) and No. FR875365-FR877509 (except FR875905; remaining partial sequences).

Biogeochemical measurements associated to deep-sea wood falls

Large organic food falls to the deep sea - such as whale carcasses and wood logs - support the development of reduced, sulfidic niches in an otherwise oxygenated, oligotrophic deep-sea environment. These transient hot spot ecosystems may serve the dispersal of highly adapted chemosynthetic organisms such as thiotrophic bivalves and siboglinid worms. Here we investigated the biogeochemical and microbiological processes leading to the development of sulfidic niches. Wood colonization experiments were carried out for the duration of one year in the vicinity of a cold seep area in the Nile deep-sea fan (Eastern Mediterranean) at depths of 1690 m. Wood logs were deployed in 2006 during the BIONIL cruise (RV Meteor M70/2 with ROV Quest, Marum, Germany) and sampled in 2007 during the Medeco-2 cruise (RV Pourquoi Pas? with ROV Victor 6000, Ifremer, France). Wood-boring bivalves played a key role in the initial degradation of the wood, the dispersal of wood chips and fecal matter around the wood log, and the provision of colonization surfaces to other organisms. Total oxygen uptake measured with a ROV-operated benthic chamber module was higher at the wood (0.5 m away) in contrast to 10 m away at a reference site (25 mmol m-2 d-1 and 1 mmol m-2 d-1, respectively), indicating an increased activity of sedimentary communities around the wood falls. Bacterial cell numbers associated with wood increased substantially from freshly submerged wood to the wood chip/fecal matter layer next to the wood experiments, as determined with Acridine Orange Direct Counts (AODC) and DAPI-stained counts. Microsensor measurements of sulfide, oxygen and pH were conducted ex situ. Sulfide fluxes were higher at the wood experiments when compared to reference measurements (19 and 32 mmol m-2 d-1 vs. 0 and 16 mmol -2 d-1, respectively). Sulfate reduction (SR) rates at the wood experiments were determined in ex situ incubations (1.3 and 2.0 mmol m-2 d-1) and fell into the lower range of SR rates previously observed from other chemosynthetic habitats at cold seeps. There was no influence of wood deposition on phosphate, silicate and nitrate concentrations, but ammonium concentrations were elevated at the wood chip-sediment boundary layer. Concentrations of dissolved organic carbon were much higher at the wood experiments (wood chip-sediment boundary layer) in comparison to measurements at the reference sites, which may indicate that cellulose degradation was highest under anoxic conditions and hence enabled by anaerobic benthic bacteria, e.g. fermenters and sulfate reducers. Our observations demonstrate that, after one year, the presence of wood at the seafloor had led to the creation of sulfidic niches, comparable to what has been observed at whale falls, albeit at lower rates.