Glaciers and climate in northern Sweden during the 19th and 20th century

Our understanding of the climate of northern Sweden during the late Holocene is largely dependent on proxy-data series. These datasets remain spatially and temporally sparse and instrumental series are rare prior to the mid 19th century. Nevertheless, the glaciology and paleo-glaciology of the region has a strong potential significance for the exploration of climate change scenarios, past and future. The aim of this thesis is to investigate the 19th and 20th century climate in the northern Swedish mountain range. This provides a good opportunity to analyse the natural variability of the climate before the onset of the industrial epoch. Developing a temporal understanding of fluctuations in glacier front positions and glacier mass balance that is linked to a better understanding of their interaction and relative significance to climate is fundamental in the assessment of past climate. I have chosen to investigate previously unexplored temperature data from northern Sweden from between 1802 and 1860 and combined it with a temperature series from a synoptic station in Haparanda, which began operation in 1859, in order to create a reliable long temperature series for the period 1802 to 2002. I have also investigated two different glaciers, Pårteglaciären and Salajekna, which are located in different climatic environments. These glaciers have, from a Swedish perspective, long observational records. Furthermore, I have investigated a recurring jökulhlaup at the glacier Sälkaglaciären in order to analyse glacier-climate relationships with respect to the jökulhlaups. A number of datasets are presented, including: glacier frontal changes, in situ and photogrammetric mass balance data, in situ and satellite radar interferometry measurements of surface velocity, radar measurements, ice volume data and a temperature series. All these datasets are analysed in order to investigate the response of the glaciers to climatic stimuli, to attribute specific behaviour to particular climates and to analyse the 19th and 20th century glacier/climate relationships in northern Sweden. The 19th century was characterized by cold conditions in northern Sweden, particularly in winter. Significant changes in the amplitude of the annual temperature cycle are evident. Through the 19th century there is a marked decreasing trend in the amplitude of the data, suggesting a change towards a prevalence of maritime (westerly) air masses, something which has characterised the 20th century. The investigations on Salajekna support the conclusion that the major part of the 19th century was cold and dry. The 19th century advance of Salajekna was probably caused by colder climate in the late 18th and early 19th centuries, coupled with a weakening of the westerly airflow. The investigations on Pårteglaciären show that the glacier has a response time of ~200 years. It also suggests that there was a relatively high frequency of easterly winds providing the glacier with winter precipitation during the 19th century. Glaciers have very different response times and are sensitive to different climatic parameters. Glaciers in rather continental areas of the Subarctic and Arctic can have very long response times because of mass balance considerations and not primarily the glacier dynamics. This is of vital importance for analyzing Arctic and Subarctic glacier behaviour in a global change perspective. It is far from evident that the behaviour of the glacier fronts today reflects the present climate.

Acclimatization to 4100 m does not change capillary density or mRNA expression of potential angiogenesis regulatory factors in human skeletal muscle

[EN] Increased skeletal muscle capillary density would be a logical adaptive mechanism to chronic hypoxic exposure. However, animal studies have yielded conflicting results, and human studies are sparse. Neoformation of capillaries is dependent on endothelial growth factors such as vascular endothelial growth factor (VEGF), a known target gene for hypoxia inducible factor 1 (HIF-1). We hypothesised that prolonged exposure to high altitude increases muscle capillary density and that this can be explained by an enhanced HIF-1alpha expression inducing an increase in VEGF expression. We measured mRNA levels and capillary density in muscle biopsies from vastus lateralis obtained in sea level residents (SLR; N=8) before and after 2 and 8 weeks of exposure to 4100 m altitude and in Bolivian Aymara high-altitude natives exposed to approximately 4100 m altitude (HAN; N=7). The expression of HIF-1alpha or VEGF mRNA was not changed with prolonged hypoxic exposure in SLR, and both genes were similarly expressed in SLR and HAN. In SLR, whole body mass, mean muscle fibre area and capillary to muscle fibre ratio remained unchanged during acclimatization. The capillary to fibre ratio was lower in HAN than in SLR (2.4+/-0.1 vs 3.6+/-0.2; P<0.05). In conclusion, human muscle VEGF mRNA expression and capillary density are not significantly increased by 8 weeks of exposure to high altitude and are not increased in Aymara high-altitude natives compared with sea level residents.

Expression and cellular localization of Copper transporter 2 (Ctr2) in Mus musculus

The Ctr family is an essential part of the copper homeostasis machinery and its members share sequence homology and structural and functional features. Higher eukaryotes express two members of this family Ctr1 and Ctr2. Numerous structural and functional studies are available for Ctr1, the only high affinity Cu(I) transporter thus far identified. Ctr1 holigotrimers mediate cellular copper uptake and this protein was demonstrated to be essential for embryonic development and to play a crucial role in dietary copper acquisition. Instead very little is known about Ctr2, it bears structural homology to the yeast vacuolar copper transporter, which mediates mobilization of vacuolar copper stores. Recent studies using over-expressed epitope-tagged forms of human Ctr2 suggested a function as a low affinity copper transporter that can mediate either copper uptake from the extracellular environment or mobilization of lysosomal copper stores. Using an antibody that recognizes endogenous mouse Ctr2, we studied the expression and localization of endogenous mouse Ctr2 in cell culture and in mouse models to understand its regulation and function in copper homeostasis. By immunoblot we observed a regulation of mCtr2 protein levels in a copper and Ctr1 dependent way. Our observations in cells and transgenic mice suggest that lack of Ctr1 induces a strong downregulation of Ctr2 probably by a post-translational mechanism. By indirect immunofluorescence we observed an exclusive intracellular localization in a perinuclear compartment and no co-localization with lysosomal markers. Immunofluorescence experiments in Ctr1 null cells, supported by sequence analysis, suggest that lysosomes may play a role in mCtr2 biology not as resident compartment, but as a degradation site. In appendix a LC-mass method for analysis of algal biotoxins belonging to the family of PsP (paralytic shellfish poisoning) is described.

Untersuchungen zu ionenchemischen Reaktionen und Mobilitätsmessungen an schweren Elementen in einer Puffergaszelle

Untersuchungen zu ionenchemischen Reaktionen und Mobilitätsmessungen an schweren Elementen in einer Puffergaszelle Die vorgelegte Arbeit beschreibt vorbereitende Untersuchungen zu ionenchemischen Reaktionen und Mobilitätsmessungen schwerer Elemente (Z>100) in einer mit Argon gefüllten Puffergaszelle. Dazu wurden am Element Erbium (Z=68), dem chemischen Homolog von Fermium (Z=100), zunächst in einem Fourier-Transformations-Massenspektrometer (FT/MS) Reaktionen mit Sauerstoff (O₂), Methan (CH₄) und Butylen (C₄H₈) untersucht und deren Reaktionskonstanten zu k(Er+O2)=(3,6±0,3)•10^-10cm³/s, k(Er+C4H8)=(1,3±0,1)•10^-10cm³/s gemessen. Für die Reaktion Er⁺+CH₄ wurde eine Obergrenze der Reaktionskonstante von k(Er+CH4)?,3•10^-15cm³/s bestimmt. Dieselben Reaktionen wurden anschließend in einer mit 60 mbar Argon gefüllten Puffergaszelle am Tandembeschleuniger des Max-Planck-Instituts für Kernphysik in Heidelberg studiert.Das in die Zelle eingeschossene Erbium wurde nach der Thermalisierung in einem zweistufigen Laserprozess resonant ionisiert. Diese Messungen führten zu gleichen Ergebnissen wie die FT/MS-Messungen (k(Er+O2)=3,3±0,4)•10^-10cm³/s, k(Er+CH4)?2•10^-17cm³/s). Die Reaktion von Erbium mit Butylen wurde ebenfalls beobachtet, eine Reaktionskonstante konnte jedoch nicht bestimmt werden. Die Reaktion von Erbium mit Sauerstoff wurde auch mit den direkt in die Puffergaszelle eingeschossenen Ionen ohne Laserionisation untersucht. Eine reproduzierbare Reaktionskonstante konnte nicht bestimmt werden, mögliche Ursachen werden diskutiert.Aus der Driftzeit der Ionen im Puffergas können Ionenmobilitäten bestimmt werden. Dies erlaubt Rückschlüsse auf die Ionenradien und damit auch auf Bindungslängen in Molekülen. Zwischen Plutonium und Americium wurde bei einer Driftzeit von (1,88±0,01) ms ein Driftzeitunterschied von (0,07±0,02) ms gemessen und daraus eine relative Verringerung des Ionenradius von Americium gegenüber dem von Plutonium um (3,1±1,3)% bestimmt. Relativistische Rechnungen sagen für den atomaren Radius von Americium gegenüber Plutonium eine Kontraktion in gleicher Größenordnung voraus; für Ionenradien existieren zur Zeit noch keine Rechnungen. Aus den gemessenen Driftzeiten des Plutoniums von (1,85±0,01) ms und Plutoniumoxids von (2,38±0,01) ms wurde eine Zunahme des Ionenradius des Plutoniumoxids gegenüber dem Plutonium um (28±2)% bestimmt.Außerdem wurden Reaktionen von Ruthenium (Z=44) und Osmium (Z=76), beides chemische Homologe von Hassium (Z=108), mit Sauerstoff in der FT/MS-Apparatur untersucht, mit dem Ziel widersprüchliche Messungen der Reaktionskonstanten aufzuklären.

Muslime in Ruanda – von Marginalisierung zu Integration /// Arbeitspapiere / Institut für Ethnologie und Afrikastudien ; 74

Zwischen April und Juni 1994 wurden in dem kleinen zentralafrikanischen Land Ruanda ca. 800.000 Menschen ermordet worden. Die Mehrzahl der Opfer waren Tutsi, aber auch viele Hutu verloren ihr Leben. Nahezu jede internationale und nationale Organisation versagte im Angesicht des Ausmaßes der Tragödie. Auch die in Ruanda sehr einflussreiche katholische Kirche konnte oder wollte die Massaker nicht beenden. Einzig die in der ruandischen Geschichte bis zum Genozid immer marginalisierten Muslime verweigerten in der Mehrzahl eine Teilnahme an den Massakern. Warum es zu diesem Verhalten kam, steht als Ausgangsfrage zu Beginn der Untersuchung. Im Folgenden gliedert sich die Arbeit in drei Teile – Geschichte des Islam bis 1994, Verhalten der Muslime im Völkermord von 1994 und die Veränderungen in den zehn Jahren nach dem Genozid. Die Arbeit, welche sich auf die Ergebnisse einer zweimonatigen Feldforschung und einige ältere Arbeiten zum Thema stützt, macht deutlich, dass die Geschichte der ruandischen Muslime bis 1994 durch eine kontinuierliche Marginalisierung gekennzeichnet war. Als nach dem Völkermord das außergewöhnliche Verhalten der ruandischen Muslime langsam deutlich wurde, änderte sich bei vielen Menschen und auch bei offiziellen Stellen auch die Einstellung gegenüber Muslimen.

Measurement of the differential cross section of tt pairs in pp collision at sqrt(s) = 7TeV with the ATLAS detector at the LHC

In this thesis three measurements of top-antitop differential cross section at an energy in the center of mass of 7 TeV will be shown, as a function of the transverse momentum, the mass and the rapidity of the top-antitop system. The analysis has been carried over a data sample of about 5/fb recorded with the ATLAS detector. The events have been selected with a cut based approach in the "one lepton plus jets" channel, where the lepton can be either an electron or a muon. The most relevant backgrounds (multi-jet QCD and W+jets) have been extracted using data driven methods; the others (Z+ jets, diboson and single top) have been simulated with Monte Carlo techniques. The final, background-subtracted, distributions have been corrected, using unfolding methods, for the detector and selection effects. At the end, the results have been compared with the theoretical predictions. The measurements are dominated by the systematic uncertainties and show no relevant deviation from the Standard Model predictions.

Magnetization dynamics in spin valves

Key technology applications like magnetoresistive sensors or the Magnetic Random Access Memory (MRAM) require reproducible magnetic switching mechanisms. i.e. predefined remanent states. At the same time advanced magnetic recording schemes push the magnetic switching time into the gyromagnetic regime. According to the Landau-Lifschitz-Gilbert formalism, relevant questions herein are associated with magnetic excitations (eigenmodes) and damping processes in confined magnetic thin film structures.rnObjects of study in this thesis are antiparallel pinned synthetic spin valves as they are extensively used as read heads in today’s magnetic storage devices. In such devices a ferromagnetic layer of high coercivity is stabilized via an exchange bias field by an antiferromagnet. A second hard magnetic layer, separated by a non-magnetic spacer of defined thickness, aligns antiparallel to the first. The orientation of the magnetization vector in the third ferromagnetic NiFe layer of low coercivity - the freelayer - is then sensed by the Giant MagnetoResistance (GMR) effect. This thesis reports results of element specific Time Resolved Photo-Emission Electron Microscopy (TR-PEEM) to image the magnetization dynamics of the free layer alone via X-ray Circular Dichroism (XMCD) at the Ni-L3 X-ray absorption edge.rnThe ferromagnetic systems, i.e. micron-sized spin valve stacks of typically deltaR/R = 15% and Permalloy single layers, were deposited onto the pulse leading centre stripe of coplanar wave guides, built in thin film wafer technology. The ferromagnetic platelets have been applied with varying geometry (rectangles, ellipses and squares), lateral dimension (in the range of several micrometers) and orientation to the magnetic field pulse to study the magnetization behaviour in dependence of these magnitudes. The observation of magnetic switching processes in the gigahertz range became only possible due to the joined effort of producing ultra-short X-ray pulses at the synchrotron source BESSY II (operated in the so-called low-alpha mode) and optimizing the wave guide design of the samples for high frequency electromagnetic excitation (FWHM typically several 100 ps). Space and time resolution of the experiment could be reduced to d = 100 nm and deltat = 15 ps, respectively.rnIn conclusion, it could be shown that the magnetization dynamics of the free layer of a synthetic GMR spin valve stack deviates significantly from a simple phase coherent rotation. In fact, the dynamic response of the free layer is a superposition of an averaged critically damped precessional motion and localized higher order spin wave modes. In a square platelet a standing spin wave with a period of 600 ps (1.7 GHz) was observed. At a first glance, the damping coefficient was found to be independent of the shape of the spin-valve element, thus favouring the model of homogeneous rotation and damping. Only by building the difference in the magnetic rotation between the central region and the outer rim of the platelet, the spin wave becomes visible. As they provide an additional efficient channel for energy dissipation, spin waves contribute to a higher effective damping coefficient (alpha = 0.01). Damping and magnetic switching behaviour in spin valves thus depend on the geometry of the element. Micromagnetic simulations reproduce the observed higher-order spin wave mode.rnBesides the short-run behaviour of the magnetization of spin valves Permalloy single layers with thicknesses ranging from 3 to 40 nm have been studied. The phase velocity of a spin wave in a 3 nm thick ellipse could be determined to 8.100 m/s. In a rectangular structure exhibiting a Landau-Lifschitz like domain pattern, the speed of the field pulse induced displacement of a 90°-Néel wall has been determined to 15.000 m/s.rn

Gespeicherte Ionen in der Paulfalle: Voruntersuchungen zur Lebensdauermessung des metastabilen 6D-3/2-Zustands des 226 Ra +, Speichereigenschaften von 138 Ba + und 28 N 2 + bei Variation des Puffergasdrucks

Auf Paulfallen basierende Experimente spielen eine wichtige Rolle in verschiedenen Bereichen der Physik, z.B. der Atomphysik zum Test theoretischer Modelle und der Massenspektroskopie. Die vorliegende Arbeit widmet sich beiden Themengebieten und gliedert sich entsprechend in zwei Teilbereiche: 1) Erdalkali-Ionen sind aufgrund ihrer Energieniveaus optimale Kandidaten für Laserspektroskopie-Experimente mit Ionenfallen und bestens geeignet, um mittels der spektroskopischen Daten die theoretischen Modelle zu testen. Lediglich für Ra+ fehlen bislang als einzigem Erdalkali-Ion diese Daten wie z.B. die Lebensdauern der metastabilen Niveaus. Diese wären auch von Interesse für bereits geplante Radium-Experimente zur Paritätsverletzung. Im ersten Teil dieser Arbeit wird der Aufbau eines Laser-Paulfallenexperiments zur Messung der Lebensdauer des 6D3/2 Zustands von 226Ra+ dokumentiert und es werden Testmessungen mit 138Ba+ vorgestellt. 2) Für die Verwendung der Paulfalle in der Massenspektroskopie und zur Analyse von Reaktionsprodukten ist die Kenntnis der Lage der im Speicherbereich auftretenden nichtlinearen Resonanzen wesentlich, ebenso wie deren Veränderung durch Dämpfung und Raumladung. Im zweiten Teil dieser Arbeit werden detaillierte Untersuchungen der Speicherung großer puffergasgekühlter Ionenwolken an zwei unterschiedlichen Paulfallen-Experimenten vorgestellt. Am ersten wurden 138Ba+-Ionenwolken kontinuierlich durch Laserspektroskopie bzw. über einen elektronischen Nachweis beobachtet, während das zweite N2+-Molekülionen automatisiert destruktiv nachwies. Am N2+-Experiment wurden zwei hochaufgelöste Messungen des ersten Speicherbereichs durchgeführt, die erstmals eine direkte Überprüfung der theoretisch berechneten Verläufe der Resonanzen mit experimentellen Daten erlauben. Die Nachweiseichung ermöglichte dabei zum ersten Mal die Angabe absoluter Ionenzahlen. Im Gegensatz zu vergleichbaren früheren Messungen wurden hierbei die sich überlagernden Speicherbereiche von 4 simultan gespeicherten Ionensorten beobachtet und zur Analyse der Resonanzen herangezogen. Die nichtlinearen Resonanzen wurden untersucht bei Variation von Puffergasdruck und Ionenzahl, wobei kollektive Resonanzen ohne zusätzliche externe Anregung beobachtet wurden. Die gemessenen Raumladungsverschiebungen wurden mit theoretischen Modellen verglichen. Bei Variation des Puffergasdrucks wurde mit Bariumionen die räumliche Ausdehnung der Ionenwolke gemessen und mit Stickstoffionen die Verschiebung des Punktes optimaler Speicherung bestimmt. Dabei wurde festgestellt, daß der zum Ioneneinfang optimale Puffergasdruck kleiner ist als der, bei dem die längsten Speicherdauern erzielt werden. Mit gespeicherten N2+-Ionen wurde die Position extern angeregter kollektiver und individueller Resonanzen im Frequenzspektrum bei Änderung der Parameter Ionenzahl, Puffergasdruck und Dauer der Anregung untersucht, ebenso wie die Resonanzform, die mit theoretischen Linienformen verglichen wurde. Bei Änderung der Fallenparameter wurden verstärkende Effekte zwischen nahen kollektiven Resonanzen festgestellt. Die Beobachtung, welche der im Frequenzspektrum vorher identifizierten Bewegungs-Resonanzen sich bei Variation der Fallenparameter a bzw. q überlagern, ermöglicht eine bislang nicht beschriebene einfache Methode der Bestimmung von nichtlinearen Resonanzen im Stabilitätsdiagramm.

Fast and accurate numerical solutions in some problems of particle and radiation transport: synthetic acceleration for the method of short characteristics, Doppler-broadened scattering kernel, remote sensing of the cryosphere

The aim of this work is to present various aspects of numerical simulation of particle and radiation transport for industrial and environmental protection applications, to enable the analysis of complex physical processes in a fast, reliable, and efficient way. In the first part we deal with speed-up of numerical simulation of neutron transport for nuclear reactor core analysis. The convergence properties of the source iteration scheme of the Method of Characteristics applied to be heterogeneous structured geometries has been enhanced by means of Boundary Projection Acceleration, enabling the study of 2D and 3D geometries with transport theory without spatial homogenization. The computational performances have been verified with the C5G7 2D and 3D benchmarks, showing a sensible reduction of iterations and CPU time. The second part is devoted to the study of temperature-dependent elastic scattering of neutrons for heavy isotopes near to the thermal zone. A numerical computation of the Doppler convolution of the elastic scattering kernel based on the gas model is presented, for a general energy dependent cross section and scattering law in the center of mass system. The range of integration has been optimized employing a numerical cutoff, allowing a faster numerical evaluation of the convolution integral. Legendre moments of the transfer kernel are subsequently obtained by direct quadrature and a numerical analysis of the convergence is presented. In the third part we focus our attention to remote sensing applications of radiative transfer employed to investigate the Earth's cryosphere. The photon transport equation is applied to simulate reflectivity of glaciers varying the age of the layer of snow or ice, its thickness, the presence or not other underlying layers, the degree of dust included in the snow, creating a framework able to decipher spectral signals collected by orbiting detectors.

Study of 3 Lambda H and 4 Lambda H in the reaction of 6 Li + 12 C at 2 A GeV

Die Produktion von Hyperkernen wurde in peripheren Schwerionenreaktionen untersucht, bei denen eine Kohlenstofffolie mit $^6$Li Projektilen mit einer Strahlenergie von $2 A$~GeV bestrahlt wurde. Es konnten klare Signale f{"{u}}r $Lambda$, $^3_{Lambda}$H, $^4_{Lambda}$H in deren jeweiligen invarianten Massenverteilungen aus Mesonenzerfall beobachtet werden.rnrnIn dieser Arbeit wird eine unabh{"{a}}ngige Datenauswertung vorgelegt, die eine Verifizierung fr"{u}herer Ergebnisse der HypHI Kollaboration zum Ziel hatte. Zu diesem Zweck wurde eine neue Track-Rekonstruktion, basierend auf einem Kalman-Filter-Ansatz, und zwei unterschiedliche Algorithmen zur Rekonstruktion sekund"{a}rer Vertices entwickelt.rn%-Rekonstruktionsalgorithmen .rnrnDie invarianten Massen des $Lambda$-Hyperon und der $^3_{Lambda}$H- und $^4_{Lambda}$H-Hyperkerne wurden mit $1109.6 pm 0.4$, $2981.0 pm 0.3$ und $3898.1 pm 0.7$~MeV$/c^2$ und statistischen Signifikanzen von $9.8sigma$, $12.8sigma$ beziehungsweise $7.3sigma$ bestimmt. Die in dieser Arbeit erhaltenen Ergebnisse stimmen mit der fr{"{u}}heren Auswertung {"{u}}berein.rnrnDas Ausbeutenverh{"{a}}ltnis der beiden Hyperkerne wurde als $N(^3_{Lambda}$H)/$N(^4_{Lambda}$H)$ sim 3$ bestimmt. Das deutet darauf hin, dass der Produktionsmechanismus f{"{u}}r Hyperkerne in Schwerionen-induzierten Reaktionen im Projektil-Rapidit{"{a}}tsbereich nicht allein durch einen Koaleszenzmechanismus beschrieben werden kann, sondern dass auch sekund{"{a}}re Pion-/Kaon-induzierte Reaktionen und Fermi-Aufbruch involviert sind.rn

Different molecular and structural adaptations with eccentric and conventional strength training in elderly men and women

Reprogramming of gene expression contributes to structural and functional adaptation of muscle tissue in response to altered use. The aim of this study was to investigate mechanisms for observed improvements in leg extension strength, gain in relative thigh muscle mass and loss of body and thigh fat content in response to eccentric and conventional strength training in elderly men (n = 14) and women (n = 14; average age of the men and women: 80.1 ± 3.7 years) by means of structural and molecular analyses. Biopsies were collected from m. vastus lateralis in the resting state before and after 12 weeks of training with two weekly resistance exercise sessions (RET) or eccentric ergometer sessions (EET). Gene expression was analyzed using custom-designed low-density PCR arrays. Muscle ultrastructure was evaluated using EM morphometry. Gain in thigh muscle mass was paralleled by an increase in muscle fiber cross-sectional area (hypertrophy) with RET but not with EET, where muscle growth is likely occurring by the addition of sarcomeres in series or by hyperplasia. The expression of transcripts encoding factors involved in muscle growth, repair and remodeling (e.g., IGF-1, HGF, MYOG, MYH3) was increased to a larger extent after EET than RET. MicroRNA 1 expression was decreased independent of the training modality, and was paralleled by an increased expression of IGF-1 representing a potential target. IGF-1 is a potent promoter of muscle growth, and its regulation by microRNA 1 may have contributed to the gain of muscle mass observed in our subjects. EET depressed genes encoding mitochondrial and metabolic transcripts. The changes of several metabolic and mitochondrial transcripts correlated significantly with changes in mitochondrial volume density. Intramyocellular lipid content was decreased after EET concomitantly with total body fat. Changes in intramyocellular lipid content correlated with changes in body fat content with both RET and EET. In the elderly, RET and EET lead to distinct molecular and structural adaptations which might contribute to the observed small quantitative differences in functional tests and body composition parameters. EET seems to be particularly convenient for the elderly with regard to improvements in body composition and strength but at the expense of reducing muscular oxidative capacity.

Purification, cDNA structure and biological significance of a single insulin-like growth factor-binding domain protein (SIBD-1) identified in the hemocytes of the spider Cupiennius salei

Cupiennius salei single insulin-like growth factor-binding domain protein (SIBD-1), which exhibits an IGFBP N-terminal domain-like profile, was identified in the hemocytes of the spider C. salei. SIBD-1 was purified by RP-HPLC and the sequence determined by a combination of Edman degradation and 5'-3'- RACE PCR. The peptide (8676.08 Da) is composed of 78 amino acids, contains six intrachain disulphide bridges and carries a modified Thr residue at position 2. SIBD-1 mRNA expression was detected by quantitative real-time PCR mainly in hemocytes, but also in the subesophageal nerve mass and muscle. After infection, the SIBD-1 content in the hemocytes decreases and, simultaneously, the temporal SIBD-1 expression seems to be down-regulated. Two further peptides, SIBD-2 and IGFBP-rP1, also exhibiting IGFBP N-terminal domain variants with unknown functions, were identified on cDNA level in spider hemocytes and venom glands. We conclude that SIBD-1 may play an important role in the immune system of spiders.

Wild immunology: converging on the real world

Recently, the Centre for Immunity, Infection and Evolution sponsored a one-day symposium entitled "Wild Immunology." The CIIE is a new Wellcome Trust-funded initiative with the remit to connect evolutionary biology and ecology with research in immunology and infectious diseases in order to gain an interdisciplinary perspective on challenges to global health. The central question of the symposium was, "Why should we try to understand infection and immunity in wild systems?" Specifically, how does the immune response operate in the wild and how do multiple coinfections and commensalism affect immune responses and host health in these wild systems? The symposium brought together a broad program of speakers, ranging from laboratory immunologists to infectious disease ecologists, working on wild birds, unmanaged animals, wild and laboratory rodents, and on questions ranging from the dynamics of coinfection to how commensal bacteria affect the development of the immune system. The meeting on wild immunology, organized by Amy Pedersen, Simon Babayan, and Rick Maizels, was held at the University of Edinburgh on 30 June 2011.

Transforming growth factor-beta inhibits the expression of clock genes

Disturbances of sleep-wake rhythms are an important problem in Alzheimer's disease (AD). Circadian rhythms are regulated by clock genes. Transforming growth factor-beta (TGF-β) is overexpressed in neurons in AD and is the only cytokine that is increased in cerebrospinal fluid (CSF). Our data show that TGF-β2 inhibits the expression of the clock genes Period (Per)1, Per2, and Rev-erbα, and of the clock-controlled genes D-site albumin promoter binding protein (Dbp) and thyrotroph embryonic factor (Tef). However, our results showed that TGF-β2 did not alter the expression of brain and muscle Arnt-like protein-1 (Bmal1). The concentrations of TGF-β2 in the CSF of 2 of 16 AD patients and of 1 of 7 patients with mild cognitive impairment were in the dose range required to suppress the expression of clock genes. TGF-β2-induced dysregulation of clock genes may alter neuronal pathways, which may be causally related to abnormal sleep-wake rhythms in AD patients.

Metacommunity Dynamics Of Benthic Macroinvertebrates In A Large River

Metacommunity ecology focuses on the interaction between local communities and is inherently linked to dispersal as a result. Within this framework, communities are structured by a combination of in-site responses to the immediate environment (species sorting), stochasticity (patch dynamics), and connections to other communities via distance between communities and dispersal (neutrality), and source-sink dynamics (mass effects; see Chapter 1 for a detailed description of metacommunity theory, the study site, and macroinvertebrate communities found). In Chapter 2 I describe spatial scale of study and dispersal ability as both have the ability to influence the degree to which communities interact. However, little is known about how these factors influence the importance of all metacommunity dynamics. I compared dispersal mode of immature aquatic insects and dispersal ability of winged adults across multiple spatial scales in a large river. The strongest drivers of river communities were patch dynamics, followed by species sorting, then neutrality. Active dispersers during aquatic lifestages on average exhibited lower patch dynamics, higher species sorting, and significant mass effects compared to passive dispersers. Active and strong dispersers also had a scale-independent influence of neutrality, while neutrality was stronger at broader spatial scale for passive and weak dispersers. These results indicate as dispersal ability increases patch dynamics decreases, species sorting increases, and neutrality should decrease. The perceived influence of neutrality may also be dependent on spatial scale and dispersal ability. In Chapter 3 I describe how river benthic macroinvertebrate communities may influence tributary invertebrate communities via adult flight and tributaries may influence mainstem communities via immature drift. This relationship may also depend on relative mainstem and tributary size, as well as abiotic tributary influence on mainstem habitat. To investigate the interaction between a larger river and tributary I sampled mainstem benthic invertebrate communities and quantified habitat of a 7th order river (West Branch Susquehanna River) above and below a 5th order tributary confluence, as well as 0.95-3.2 km upstream in the tributary. Non-metric multidimensional scaling showed similar patterns of clustering between sampling locations for both habitat characteristics and invertebrate communities. In addition, mainstem river communities and habitat directly downstream of the tributary confluence cluster tightly together, intermediate between tributary and mid-channel river samples. In Bray-Curtis dissimilarity comparisons between tributary and mainstem river communities the furthest upstream tributary communities were least similar to river communities. Middle tributary samples were also closest by Euclidean distance to the upstream mainstem riffle and exhibited higher similarity to mid-channel samples than the furthest downstream tributary communities. My results indicate river and tributary benthic invertebrate communities may interact and likely result in direct and indirect mass effects of a tributary on the downstream mainstem community by invertebrate drift and habitat restructuring via material delivery from the tributary. I also showed likely direct effects of adult dispersal from the river and oviposition in proximal tributary locations where Euclidian, rather than river, distance may be more important in determining river-tributary interactions.