Maternal transfer of IgE and subsequent development of IgE responses in the horse (Equus callabus)

Immunoglobulin E (IgE) mediates the immune response to parasites, but can also cause allergies. In humans maternal IgE is not transferred to cord blood and high levels of cord blood IgE are associated with subsequent allergy. In horses, both maternal IgG and IgE are transferred via colostrum; the IgE levels in the mare's serum, the colostrum and the foal's serum are correlated but the consequences of IgE transfer to foals are not known. By about 6 weeks of age the levels of IgE in foal serum have dropped to a nadir, at 6 months of age the level of IgE has risen only very slightly and is no longer correlated with the levels seen at birth, IgE(+) B-cells could be detected in lymphoid follicles of some foals at this age. Surprisingly, the levels of total IgE detected in a foals serum at 6 months of age are significantly correlated with the level in its serum at 1, 2 and even 3 years of age suggesting that by 6 months of age the foals are synthesizing IgE and that a pattern of relatively higher or lower total serum IgE has been established. The neonatal intestinal mucosa contained connective tissue mast cells which stained for bound IgE in foals up to 9 weeks of age but not mucosal mast cells, thereafter, the intestinal mast cells were IgE negative until 6 months of age. IgE antibodies to Culicoides nubeculosus salivary antigens were detected in Swiss born foals from imported Icelandic mares allergic to Culicoides spp. yet the foals showed no signs of skin sensitization and such second generation foals are known not to have an increased risk of developing allergy to Culicoides. Overall this evidence suggests there is a minimal effector role of maternal IgE also that maternal IgE has waned prior to the onset of IgE synthesis in foals and does not support maternal priming of IgE responses in foals. Furthermore the total levels of IgE in any given foal are seen to be relatively high or low from soon after the onset of IgE synthesis, and most likely they are determined by genetic factors.

Seven novel KIT mutations in horses with white coat colour phenotypes

White coat colour in horses is inherited as a monogenic autosomal dominant trait showing a variable expression of coat depigmentation. Mutations in the KIT gene have previously been shown to cause white coat colour phenotypes in pigs, mice and humans. We recently also demonstrated that four independent mutations in the equine KIT gene are responsible for the dominant white coat colour phenotype in various horse breeds. We have now analysed additional horse families segregating for white coat colour phenotypes and report seven new KIT mutations in independent Thoroughbred, Icelandic Horse, German Holstein, Quarter Horse and South German Draft Horse families. In four of the seven families, only one single white horse, presumably representing the founder for each of the four respective mutations, was available for genotyping. The newly reported mutations comprise two frameshift mutations (c.1126_1129delGAAC; c.2193delG), two missense mutations (c.856G>A; c.1789G>A) and three splice site mutations (c.338-1G>C; c.2222-1G>A; c.2684+1G>A). White phenotypes in horses show a remarkable allelic heterogeneity. In fact, a higher number of alleles are molecularly characterized at the equine KIT gene than for any other known gene in livestock species.

Dramaturgie der Seuche. Zur Verarbeitung von Aids in Literatur, Theater und Film

Gegenstand / Untersuchungskorpus Die massenmediale Aufbereitung von Aids ist bereits seit den Anfängen der geisteswissenschaftlichen Beschäftigung mit diesem Thema ein zentraler Gegenstand kritischer Betrachtung. Demgegenüber stellt sich die systematische Erforschung des Beitrages von eher fiktionalen Gattungen zur gesellschaftlichen Verarbeitung von Aids ein Forschungsdesiderat dar. Die Dissertation „Dramaturgie der Seuche“ schliesst mit der Fokussierung auf Literatur, Theater und Film diese Lücke. Die dezidiert interdisziplinäre Auswahl des Untersuchungskorpus’ liefert eine Zusammenschau der Funktionen, die diese Gattungen im Laufe der Zeit innerhalb des Aids-Diskurses übernommen haben. Die Arbeit zeigt die komplexen Wechselverhältnisse zwischen den Massenmedien, den fiktionalen Gattungen sowie der medizinischen Kommunikation auf. Fragedesign auf der Höhe der aktuellen Forschung Gegenwärtig ist erneut ein Interesse kultur- und sozialwissenschaftlicher Disziplinen am Thema Aids zu beobachten. Eine junge Forschergeneration nimmt sich des Themas an und beleuchtet die Auseinandersetzung mit Aids an Hand neuer Fragestellungen und mit neuen Methoden. Im Mittelpunkt dieser wissenschaftlichen Auseinandersetzung stehen die reflektierte Historisierung und Kontextualisierung des Aids-Diskurses seit den 1980er-Jahren. Die Dissertation „Dramaturgie der Seuche“ positioniert sich mit ihrer Frage nach der Struktur und der Entwicklung der gesellschaftlichen Auseinandersetzung mit Aids seit den Anfängen bis zur Gegenwart innerhalb dieses aktuellen Forschungsfeldes. Die Herangehensweise unterscheidet sich damit deutlich von den Forschungen der 1990er-Jahre, die eher von Betroffenheit und/oder unmittelbarer Kritik am Aids-Diskurs in den Massenmedien geprägt war. Zugleich verschafft die kritische Re-Lektüre der zentralen Publikationen zum Thema Aids, etwa von Susan Sontag oder Sander L. Gilman, diesen eine kritische Aktualisierung. Innovatives Methodendesign Um dem interdiszplinären Korpus und der kulturwissenschaftlich inspirierten Fragestellung gerecht zu werden, entwirft die Dissertation ein innovatives Methodendesign, das diskursanalytische und systemtheoretische Ansätze mit theater-, literatur- und filmwissenschaftlichen Analyseinstrumenten synthetisiert. Dieses leistet in der Anwendung sowohl eine präzise und adäquate Tiefenanalyse der untersuchten Texte, Bilder und Filme als auch eine Auswertung dieser Ergebnisse auf einer abstrakteren Ebene, die die komplexe Struktur der Entwicklung des Aids-Diskurses seit den 1980er-Jahren bis heute überzeugend und anschaulich darlegt. Das entworfene Methodendesign lässt sich auf andere Gegenstände anwenden und verspricht ebenso präzise wie innovative Ergebnisse. Ergebnisse: Nutzen für die Öffentlichkeit Die analytische Auseinandersetzung mit der letzten grossen Seuche innerhalb der westlichen Welt birgt nicht nur in der Rückschau auf die letzten Dekaden einen Mehrwert für die Öffentlichkeit. Die regelmässige Wiederkehr von epidemischen Szenarien – BSE, SARS, Vogel- und Schweinegrippe und jüngst EHEC – zeigt, dass ein kritischer Blick auf die sich wiederholenden dramaturgischen Muster des Redens über ansteckende Krankheiten nottut. Die Dissertation „Dramaturgie der Seuche“ trägt dazu bei, die Muster des Seuchendiskurses zu erkennen und reflektiert und kritisch mit der Berichterstattung in den Medien wie auch mit den kursierenden Urban Legends umzugehen. Der Aufbau der Argumentation und der sprachliche Stil verbinden wissenschaftliche Genauigkeit mit Allgemeinverständlichkeit. Dadurch wird die Arbeit breit rezipierbar.

Genomic heterogeneity of small ruminant lentiviruses detected by PCR

In order to detect a large spectrum of small ruminant lentiviruses, primers for PCR were chosen in conserved parts of the LTR and GAG genes of Icelandic Visna virus 1514 and of the POL gene of caprine arthritis-encephalitis virus. This set of primers was tested in six different caprine arthritis-encephalitis virus (CAEV)- and Maedi-Visna virus isolates of Dutch, American and Swiss origin. The LTR primers allowed the detection of the corresponding fragments of all isolates. The GAG primers allowed amplification of the corresponding fragments of all but the Swiss Maedi-Visna virus strain OLV. Using the POL primers, one Maedi-Visna- and two caprine arthritis-encephalitis virus strains were detected after one round of amplification. Sequencing of the GAG and POL amplification products and comparison to Icelandic Visna virus and CAEV strain CO revealed total heterogeneity of 38% for the GAG- and 28% for the POL fragment. The virus strains studied fall into two groups which are more closely related to one another than to Icelandic Visna virus.

Kinetics and kinematics of the tölt: effects of rider interaction and shoeing manipulations

Introduction . Compared to most equine horse breeds which are able to walk, trot and canter /gallop, the gait repertoire of the Icelandic horses additionally includes the lateral gait tölt and frequently also the pace. With respect to the tölt gait, special shoeing, saddling and riding techniques have been developed for Icelandic horses in order to enhance its expressiveness and regularity. Toes are left unnaturally long and heavy shoes and paddings, as well as weighted boots are used to enforce the individual gait predisposition. For the same reason, the rider is placed more caudally to the horse's centre of mass as compared to other riding techniques. The biomechanical impact of these methods on the health of the locomotor system has so far never been subject of systematic research. Objectives . The aims of the presented study are (1) to describe the kinetic and kinematic characteristics of the tölt performed on a treadmill, (2) to understand the mechanical consequences of shoeing manipulation (long hooves, weighted boots) on the loading and protraction movement of the limbs, as well as (3) to study the pressure distribution and effects on the gait pattern of 3 different saddle types used for riding Icelandic horses. Materials and methods . Gait analysis was carried out in 13 Icelandic horses at walk and at slow and medium tölting and trotting speeds on a high-speed treadmill instrumented for measuring vertical ground reaction forces as well as temporal and spatial gait variables. Kinematic data of horse, rider and saddle were measured simultaneously. Gait analysis was first carried out with high, long hooves (SH) without and in combination with weighted boots (ad aim (2)). Afterwards, horses were re-shod according to current horseshoeing standards (SN) and gait analysis was repeated (ad aims (1) and (2)). In a second trial, horses were additionally equipped with a pressure sensitive saddle mat and were ridden with a dressage-like saddle (SDres), an Icelandic saddle (Slcel) and a saddle cushion (SCush) in the standard saddle position (ad aim 3). Results and conclusions . Compared to trot at the same speed, tölting horses had a higher stride rate and lower stride impulses. At the tölt loading of the forelimbs was increased in form of higher peak vertical forces (Fzpeak) due to shorter relative stance durations (StDrel). Conversely, in the hindlimbs, longer StDrel resulted in lower Fzpeak. Despite the higher head-neck position at tölt, there was no measurable shift in weight to the hindlimbs. Footfall rhythm was in most horses laterally coupled at the tölt and frequently had a slight fourbeat and a very short suspension phase at trot; underlining the fact that performance of correct gaits in Icelandic horses needs special training. Gait performance as it is currently judged in competition could be improved using a shoeing with SH, resulting in a 21 ± 5 mm longer dorsal hoof wall, but also a weight gain of 273 ± 50 g at the distal limb due to heavier shoeing material. Compared to SN, SH led to a lower stride rate, a longer stride length and a higher, but not wider, forelimb protraction arc, which were also positively associated with speed. At the tölt, the footfall rhythm showed less tendency to lateral couplets and at the trot, the suspension phase was longer. However, on the long term, SH may have negative implications for the health of the palmar structures of the distal foot by increased limb impulses, higher torques at breakover (up to 20%); as well as peak vertical forces at faster speeds. Compared to the shoeing style, the saddle type had less influence on limb forces or movements. The slight weight shift to the rear with SCush and Slcel may be explained by the more caudal position of the rider relative to the horse's back. With SCush, pressure was highest under the cranial part of the saddle, whereas the saddles with trees had more pressure under the caudal area.

The use of electromyography interference pattern analysis to determine muscle force of the deep digital flexor muscle in healthy and laminitic horses

BACKGROUND: In equine laminitis, the deep digital flexor muscle (DDFM) appears to have increased muscle force, but evidence-based confirmation is lacking. OBJECTIVES: The purpose of this study was to test if the DDFM of laminitic equines has an increased muscle force detectable by needle electromyography interference pattern analysis (IPA). ANIMALS AND METHODS: The control group included six Royal Dutch Sport horses, three Shetland ponies and one Welsh pony [10 healthy, sound adults weighing 411 ± 217 kg (mean ± SD) and aged 10 ± 5 years]. The laminitic group included three Royal Dutch Sport horses, one Friesian, one Haflinger, one Icelandic horse, one Welsh pony, one miniature Appaloosa and six Shetland ponies (14 adults, weight 310 ± 178 kg, aged 13 ± 6 years) with acute/chronic laminitis. The electromyography IPA measurements included firing rate, turns/second (T), amplitude/turn (M) and M/T ratio. Statistical analysis used a general linear model with outcomes transformed to geometric means. RESULTS: The firing rate of the total laminitic group was higher than the total control group. This difference was smaller for the ponies compared to the horses; in the horses, the geometric mean difference of the laminitic group was 1.73 [geometric 95% confidence interval (CI) 1.29-2.32], and in the ponies this value was 1.09 (geometric 95% CI 0.82-1.45). CONCLUSION AND CLINICAL RELEVANCE: In human medicine, an increased firing rate is characteristic of increased muscle force. Thus, the increased firing rate of the DDFM in the context of laminitis suggests an elevated muscle force. However, this seems to be only a partial effect as in this study, the unchanged turns/second and amplitude/turn failed to prove the recruitment of larger motor units with larger amplitude motor unit potentials in laminitic equids.

[The treatment of arterial hypertension in elderly men in Iceland].

The choice of antihypertensive therapy in elderly Icelanders is unknown. In the database of the Icelandic Heart Association 1145 men, aged 70-84 were alive in 1994. Eight hundred thirty-four came to the Heart Association Clinic, 429 of whom either had hypertension or were found to be hypertensive on examination. The prevalence of hypertension in elderly Icelandic men was therefore about 50%. One hundred fifty-seven men took drugs for hypertension. Ninety-five of them were treated with a single drug, 49 with two drugs and five with three drugs. The type of drugs was unknown concerning eight men. Diuretics and ß-blockers were dominant. Although the comparison between those two classes of drugs was uncontrolled the blood pressure was significantly lower in systole on diuretics. The most common combination was ß-blockers and diuretics, then angiotensin converting enzyme inhibitors and diuretics, finally ß-blockers and calcium blockers. It is suggested that the use of diuretics should be increased in this age group.

Deep-sea sediment core PS2644 record from the southern Greenland Sea

The PS2644 deep-sea core sequence, retrieved from the northwestern margin of Iceland and covering the last 86 ka, exhibits high sedimentation rates during the last glacial cycle that allow the clear distinction of Greenland stadial (GS)/ interstadial (GI) cycles in the various proxy records. Abundance records of rhyolitic, basaltic and tachylytic tephra grains reveal several maxima. Tephra grains of all types were geochemically analyzed in 44 levels. A total of 92 tephras with a distinctive character have been defined within the glacial sequence of gravity core PS2644-5, whereas the Holocene record is dominated by reworked Vedde Ash grains and not suitable for tephra stratigraphic work. Of the 92 tephras only 19 geochemical populations have been linked with confidence to previously defined tephras such as from the Vedde Ash, Faeroe Marine Ash Zones (FMAZ) II and III and North Atlantic Ash Zone (NAAZ) II. For the glacial period informal names were given to 78 new tephras, most of which are basaltic tephras. Several of these layers have a unique geochemical character and might become new chronostratigraphic markers in the North Atlantic region. Linking the tephra populations to the volcanic system producing them, respectively, revealed that Icelandic eruptions dominate with 83 tephra geochemical populations and Jan Mayen with 9. Around 48% of the informal tephra layers linked to the Icelandic volcanic province are produced from either the Grimsvötn or the Veidivötn-Bardarbunga volcanic systems. The intervals spanning from Greenland Stadial (GS) 3 to Greenland Interstadial (GI) 4 (24.5-29 ka BP), from GI 8 to GS 10 (36.9-40.5 ka BP) and from GI 14 to GI 15.2 (50-56 ka BP) are the periods with the highest number of eruptions, all of which are associated with known tephra zones.

Stable oxygen isotope record from Greenland ice cores

Twenty ice cores drilled in medium to high accumulation areas of the Greenland ice sheet have been used to extract seasonally resolved stable isotope records. Relationships between the seasonal stable isotope data and Greenland and Icelandic temperatures as well as atmospheric flow are investigated for the past 150-200 years. The winter season stable isotope data are found to be influenced by the North Atlantic Oscillation (NAO) and very closely related to SW Greenland temperatures. The linear correlation between the first principal component of the winter season stable isotope data and Greenland winter temperatures is 0.71 for seasonally resolved data and 0.83 for decadally filtered data. The summer season stable isotope data display higher correlations with Stykkisholmur summer temperatures and North Atlantic SST conditions than with SW Greenland temperatures. The linear correlation between Stykkisholmur summer temperatures and the first principal component of the summer season stable isotope data is 0.56, increasing to 0.66 for decadally filtered data. Winter season stable isotope data from ice core records that reach more than 1400 years back in time suggest that the warm period that began in the 1920s raised southern Greenland temperatures to the same level as those that prevailed during the warmest intervals of the Medieval Warm Period some 900-1300 years ago. This observation is supported by a southern Greenland ice core borehole temperature inversion. As Greenland borehole temperature inversions are found to correspond better with winter stable isotope data than with summer or annual average stable isotope data it is suggested that a strong local Greenland temperature signal can be extracted from the winter stable isotope data even on centennial to millennial time scales.

Age determination and stable isotope record of foraminifera of sediment core SO82_5-2

Surface and deepwater paleoclimate records in Irminger Sea core SO82-5 (59°N, 31°W) and Icelandic Sea core PS2644 (68°N, 22°W) exhibit large fluctuations in thermohaline circulation (THC) from 60 to 18 calendar kyr B.P., with a dominant periodicity of 1460 years from 46 to 22 calendar kyr B.P., matching the Dansgaard-Oeschger (D-O) cycles in the Greenland Ice Sheet Project 2 (GISP2) temperature record [Grootes and Stuiver, 1997, doi:10.1029/97JC00880]. During interstadials, summer sea surface temperatures (SSTsu) in the Irminger Sea averaged to 8°C, and sea surface salinities (SSS) averaged to ~36.5, recording a strong Irminger Current and Atlantic THC. During stadials, SSTsu dropped to 2°-4°C, in phase with SSS drops by ~1-2. They reveal major meltwater injections along with the East Greenland Current, which turned off the North Atlantic deepwater convection and hence the heat advection to the north, in harmony with various ocean circulation and ice models. On the basis of the IRD composition, icebergs came from Iceland, east Greenland, and perhaps Svalbard and other northern ice sheets. However, the southward drifting icebergs were initially jammed in the Denmark Strait, reaching the Irminger Sea only with a lag of 155-195 years. We also conclude that the abrupt stadial terminations, the D-O warming events, were tied to iceberg melt via abundant seasonal sea ice and brine water formation in the meltwater-covered northwestern North Atlantic. In the 1/1460-year frequency band, benthic ?18O brine water spikes led the temperature maxima above Greenland and in the Irminger Sea by as little as 95 years. Thus abundant brine formation, which was induced by seasonal freezing of large parts of the northwestern Atlantic, may have finally entrained a current of warm surface water from the subtropics and thereby triggered the sudden reactivation of the THC. In summary, the internal dynamics of the east Greenland ice sheet may have formed the ultimate pacemaker of D-O cycles.

Boedo y Florida en las páginas de Los Pensadores

En la Argentina tuvo lugar entre 1924 y 1930 una polémica literario–política centrada en las revistas Martín Fierro, por un lado y Los Pensadores y Claridad por el otro, referente al objetivo de la literatura y su papel en la sociedad, aspectos que ejemplifican posiciones diferentes frente a lo real, la literatura como tarea y la obra como comunicación y portadora de significado. Los dos grupos intentaron legitimar sus objetivos frente a lo canónico: Florida atacó los modelos modernista, realista y los residuos románticos, y Boedo trató de ampliar la noción de público literario. Sin embargo, la disputa motivó más leyendas que vanguardias. En esta oportunidad nos interesa analizar, desde la perspectiva de la historia de la ideas y centrados en Los Pensadores, la mencionada polémica como expresión propia de la época.

Bestiarios medievales e imaginario social

Los historiadores medievalistas se concentran, en la actualidad, en descubrir y penetrar el sistema de valores, creencias y sentimientos de hombres y mujeres de aquella época, cómo se representaban el mundo y el espíritu de una sociedad para la cual lo invisible merecía tanto interés como lo visible. Los Bestiarios fueron considerados en su época libros de historia natural y sus autores pretendieron darles características científicas, pero al dotarlos de un tono moralizante, acudir a las leyendas y apelar a los animales más inverosímiles y fantásticos concebidos por el hombre medieval, pasaron a formar parte «de aquel dominio de lo maravilloso donde se expresa el imaginario de una época». Por consiguiente, al recurrir a la alegoría como procedimiento expresivo privilegiado y procurar educar las conciencias en las reglas de la ecumenidad cristiana, de ser pretendidos textos científicos se convirtieron en una de las más sorprendentes páginas de la literatura medieval. En ellos pesa más la valoración alegórica de las criaturas descriptas que la veracidad de las descripciones. La literatura didáctica fue uno de los mecanismos que se emplearon para lograr la adhesión al ideal cristiano. Los autores de los Bestiarios describían las bestias y usaban esa descripción como base de una enseñanza alegórica. De este modo, al mismo tiempo que algunos animales representaron a Cristo, otros simbolizaron el Mal o se convirtieron en proyección de los vicios y defectos humanos. Este trabajo se propone analizar la representación literaria de algunos de estos animales como expresión del imaginario de una época.

A Middle Pleistocene nannofossil record of sediment core MD03-2699

Changes in paleoclimate and paleoproductivity patterns have been identified by analysing, in conjunction with other available proxy data, the coccolithophore assemblages from core MD03-2699, located in the Portuguese margin in the time interval from the Marine Isotope Stage (MIS) 13/14 boundary to MIS 9 (535 to 300 ka). During the Mid-Brunhes event, the assemblages associated with the eccentricity minima are characterised by higher nannoplankton accumulation rate (NAR) values and by the blooming of the opportunistic genus Gephyrocapsa. Changes in coccolithophore abundance are also related to glacial-interglacial cycles. Higher NAR and numbers of coccoliths/g mainly occurred during the interglacial periods, while these values decreased during the glacial periods. Superimposed on the glacial/interglacial cycles, climatic and paleoceanographic variability has been observed on precessional timescales. The structure of the assemblages highlights the prevailing long-term influence of the Portugal (PC) and Iberian Poleward (IPC) Currents, following half and full precession harmonics, related to the migration of the Azores High (AH) Pressure System. Small Gephyrocapsa and Coccolithus pelagicus braarudii are regarded as good indicators for periods of prevailing PC influence. Gephyrocapsa caribbeanica, Syracosphaera spp., Rhabdosphaera spp. and Umbilicosphaera sibogae denote periods of IPC influence. Our data also highlights the increased percentages of Coccolithus pelagicus pelagicus during the occurrence of episodes of very cold and low salinity surface water, probably related to abrupt climatic events and millennial-scale oscillations of the AH/Icelandic Low (IL) System.

Data from PhD thesis

The ocean quahog, Arctica islandica is the longest-lived non-colonial animal known to science. A maximum individual age of this bivalve of 405 years has been found in a population off the north western coast of Iceland. Conspicuously shorter maximum lifespan potentials (MLSPs) were recorded from other populations of A. islandica in European waters (e.g. Kiel Bay: 30 years, German Bight: 150 years) which experience wider temperature and salinity fluctuations than the clams from Iceland. The aim of my thesis was to identify possible life-prolonging physiological strategies in A. islandica and to examine the modulating effects of extrinsic factors (e.g. seawater temperature, food availability) and intrinsic factors (e.g. species-specific behavior) on these strategies. Burrowing behavior and metabolic rate depression (MRD), tissue-specific antioxidant and anaerobic capacities as well as cell-turnover (= apoptosis and proliferation) rates were investigated in A. islandica from Iceland and the German Bight. An inter-species comparison of the quahog with the epibenthic scallop Aequipecten opercularis (MLSP = 8-10 years) was carried out in order to determine whether bivalves with short lifespans and different lifestyles also feature a different pattern in cellular maintenance and repair. The combined effects of a low-metabolic lifestyle, low oxidative damage accumulation, and constant investment into cellular protection and tissue maintenance, appear to slow-down the process of physiological aging in A. islandica and to afford the extraordinarily long MLSP in this species. Standard metabolic rates were lower in A. islandica when compared to the shorter-lived A. opercularis. Furthermore, A. islandica regulate mantle cavity water PO2 to mean values < 5 kPa, a PO2 at which the formation of reactive oxygen species (ROS) in isolated gill tissues of the clams was found to be 10 times lower than at normoxic conditions (21 kPa). Burrowing and metabolic rate depression (MRD) in Icelandic specimens were more pronounced in winter, possibly supported by low seawater temperature and food availability, and seem to be key energy-saving and life-prolonging parameters in A. islandica. The signaling molecule nitric oxide (NO) may play an important role during the onset of MRD in the ocean quahog by directly inhibiting cytochome-c-oxidase at low internal oxygenation upon shell closure. In laboratory experiments, respiration of isolated A. islandica gills was completely inhibited by chemically produced NO at low experimental PO2 <= 10 kPa. During shell closure, mantle cavity water PO2 decreased to 0 kPa for longer than 24 h, a state in which ROS production is supposed to subside. Compared to other mollusk species, onset of anaerobic metabolism is late in A. islandica in the metabolically reduced state. Increased accumulation of the anaerobic metabolite succinate was initially detected in the adductor muscle of the clams after 3.5 days under anoxic incubation or in burrowed specimens. A ROS-burst was absent in isolated gill tissue of the clams following hypoxia (5 kPa)-reoxygenation (21 kPa). Accordingly, neither the activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), nor the specific content of the ROS-scavenger glutathione (GSH) was enhanced in different tissues of the ocean quahog after 3.5 days of self-induced or forced hypoxia/anoxia to prepare for an oxidative burst. While reduced ROS formation compared to routine levels lowers oxidative stress during MRD and also during surfacing, the general preservation of high cellular defense and the efficient removal and replacement of damaged cells over lifetime seem to be of crucial importance in decelerating the senescent decline in tissues of A. islandica. Along with stable antioxidant protection over 200 years of age, proliferation rates and apoptosis intensities in most investigated tissues of the ocean quahog were low, but constant over 140 years of age. Accordingly, age-dependent accumulations of protein and lipid oxidation products are lower in A. islandica tissues when compared to the shorter-lived bivalve A. opercularis. The short-lived swimming scallop is a model bivalve species representing the opposite life and aging strategy to A. islandica. In this species permanently high energy throughput, reduced investment into antioxidant defense with age, and higher accumulation of oxidation products are met by higher cell turnover rates than in the ocean quahog. The only symptoms of physiological change over age ever found in A. islandica were decreasing cell turnover rates in the heart muscle over a lifetime of 140 years. This may either indicate higher damage levels and possibly ongoing loss of functioning in the heart of aging clams, or, the opposite, lower rates of cell damage and a reduced need for cell renewal in the heart tissue of A. islandica over lifetime. Basic physiological capacities of different A. islandica populations, measured at controlled laboratory conditions, could not explain considerable discrepancies in population specific MLSPs. For example, levels of tissue-specific antioxidant capacities and cell turnover rates were similarly high in individuals from the German Bight and from Iceland. Rather than genetic differences, the local impacts of environmental conditions on behavioral and physiological traits in the ocean quahog seem to be responsible for differences in population-specific MLSPs.

Textos y contextos en narraciones orales de migrantes provincianos

La tesis se centra en el estudio de las narraciones orales de migrantes provincianos, afincados en el conurbano platense, desde 1940. Las narraciones orales se denominan, en esta tesis, de retroalimentación ya que narradores y receptores recrean su origen, sus estrategias de reinserción en una nueva comunidad y de supervivencia de sus tradiciones. Estos textos han sido considerados de acuerdo con su problemática genérica (Bajtin; 1979) como narraciones de ficción (cuentos, chistes, fábulas) y de no-ficción (crónicas personales, anécdotas) y, asimismo, observar procesos de entextualización, cuando una misma narración presenta caracteres de ambas clasificaciones. De este modo, cada texto delimita su género en la situación de narración (Bauman y Briggs: 2003) Dichas narraciones deben ser analizadas por sus contextos de enunciación (Bausinger: 1988, 8-28). Los contextos de enunciación, según Hermann Bausinger, son textual, la conversación en sí misma, situacional, las circunstancias de emisores y receptores, social, del grupo de narración, de su grupo de pertenencia y de los grupos con los que interactúa, y societal, en cuanto a las relaciones con la sociedad mayoritaria son fundamentales al punto de que dos versiones de una misma narración se analizan de acuerdo con contextos de enunciación diferentes, con significaciones sociales disímiles. Dentro de los contextos de enunciación, la tesis propone el análisis del contexto ideológico (Coto: 2008), como signo de la intersubjetividad entre narradores y receptores. El contexto ideológico se analiza a partir de la selección de lexemas relevantes con sus definiciones contextuales, para constituir redes de enunciados, que revelan la ideología de narradores y receptores. La tesis propone establecer una matriz ideológica individual y grupal, observando los lexemas recurrentes en versiones de una misma narración, sus adiciones, supresiones y cambios de significación. Además, los textos puede compararse de acuerdo con sus relaciones intratextuales, intertextuales y extratextuales, en el marco de la genética textual (Palleiro: 2004). Finalmente, la tesis propone una metodología de análisis de las narrativas orales, en el marco de la cultura popular, tradicional y folklórica, con la observación de estrategias narrativas y macrorreglas (Van Dijk: 1983), estilo y (Kerbrat-Orecchioni: 1983) y representatividad sociolingüística. (Van Dijk: 1999 y Magariños: 1993). Estas consideraciones prueban la importancia de esta tesis para los intelectuales dedicados al análisis del discurso y a la interpretación de discursos sociales de grupos minoritarios, es decir, docentes, narradores orales, sociólogos y antropólogos. Asimismo, puede ser muy útil para animadores culturales y comunicadores sociales. La tesis postula continuar estos estudios, observando las relaciones entre narrativas de ficción y de no ficción, como el rumor, la leyenda urbana y la crónica periodística