(Table 2) Stable isotope analysis of Nuttallides truempyi and Rugoglobigerina rugosa from DSDP Site 62-463

Strong climatic and temperature fluctuations mark the Late Campanian and Maastrichtian as indicated by stable isotope records from the equatorial Pacific (Site 463) and middle and high latitude South Atlantic (Sites 525, 689 and 690). The first major global cooling decreased intermediate water temperatures (IWT) by 5-6°C between 73-70 Ma. At the same time, sea surface temperature (SST) decreased by 4-5°C in middle and high latitudes. Intermediate waters (IW) temporarily warmed by 2°C in low and middle latitudes between 70-68.5 Ma. Global cooling resumed between 68.5-65.5 Ma when IWT decreased by 3-4°C and SST by 5°C in middle latitudes. About 450 ka before the Cretaceous-Tertiary boundary rapid global warming increased IWT and SST by 3-4°C, though SST in the tropics changed little. During the last 200 ka of the Maastrichtian, climate cooled rapidly with IWT and SST decreasing by 2-3°C. During the global cooling at 71-70 Ma and possibly at 67-65.5 Ma, the sources of cold intermediate waters in the equatorial Pacific, Indo-Pacific and South Atlantic were derived from the high latitude North Pacific. In contrast, during the global climate warming between 65.2-65.4 Ma, the middle latitude South Atlantic was closest to the source of IW production and implies that the low latitude Tethys played a major role in global climate change. Climate changes, sea-level fluctuations and associated restricted seaways appear to be the most likely mechanisms for the alternating sources of IW production.

Rare element concentrations measured on filtered seawater of water bottle samples during POLARSTRERN cruise ANT-XXIV/3 (GIPY5)

The concentrations of rare earth elements (REEs) in seawater display systematic variations related to weathering inputs, particle scavenging and water mass histories. Here we investigate the REE concentrations of water column profiles in the Atlantic sector of the Southern Ocean, a key region of the global circulation and primary production. The data reveal a pronounced contrast between the vertical profiles in the Antarctic Circumpolar Current (ACC) and those to the south of the ACC in the Weddell Gyre (WG). The ACC profiles exhibit the typical increase of REE concentrations with water depth and a change in the shape of the profiles from near linear for the light REEs to more convex for the heavy REEs. In contrast, the WG profiles exhibit high REE concentrations throughout the water column with only the near surface samples showing slightly reduced concentrations indicative of particle scavenging. Seawater normalised REE patterns reveal the strong remineralisation signal in the ACC with the light REEs preferentially removed in surface waters and the mirror image pattern of their preferential release in deep waters. In the WG the patterns are relatively homogenous reflecting the prevalence of well-mixed Lower Circumpolar Deep Water (LCDW) that follows shoaling isopycnals in the region. In the WG particle scavenging of REEs is comparatively small and limited to the summer months by light limitation and winter sea ice cover. Considering the surface water depletion compared to LCDW and that the surface waters of the WG are replaced every few years, the removal rate is estimated to be on the order of 1 nmol/m3/yr for La and Nd. The negative cerium anomalies observed in deep waters are some of the strongest found globally with only the deepest waters in parts of the Pacific having stronger anomalies. These deep waters have been isolated from fresh continental REE inputs during their long journey through the abyssal Indo-Pacific ocean and suggests that the high REE concentrations found in the ACC and WG reflect contributions from old deep waters.

(Table 1) Stable-isotope and eolian grain size data across the Paleocene/Eocene boundary from DSDP Hole 22-215

Deep Sea Drilling Project (DSDP) Site 215 provides an expanded section across the Paleocene/Eocene boundary, the most complete mid-latitude sequence from a Southern Hemisphere location in the Indo-Pacific area. The events of this transition occurred during a span of about 1.2 m.y. Oxygen isotope values derived from benthic foraminiferal calcite decrease by about 1.0 per mil, a decrease most likely related to warming of deep ocean waters. Turnovers of benthic foraminifera accompany d18O changes and culminate in the predominant extinction event at the end of the Paleocene Epoch. Carbon isotope ratios also shift dramatically toward lighter values near the end of the Paleocene, beginning about 0.45 m.y. after oxygen isotope values start to change. The intensity of Southern Hemisphere atmospheric circulation as recorded by grain sizes of eolian particles shows a large and rapid reduction beginning another 0.45 m.y. later. A significant reduction of zonal wind strength at the Paleocene/Eocene boundary, until now observed only at Northern Hemisphere locations, appears to have been a global phenomenon related to decreased latitudinal thermal gradients occasioned by more effective poleward heat transport via the deep ocean.

Crafting divine personae in Julian’s Oration 7

Peer reviewed

Aluminum Induces a Decrease in Cytosolic Calcium Concentration in BY-2 Tobacco Cell Cultures1

Al toxicity is a major problem that limits crop productivity on acid soils. It has been suggested that Al toxicity is linked to changes in cellular Ca homeostasis and the blockage of plasma membrane Ca2+-permeable channels. BY-2 suspension-cultured cells of tobacco (Nicotiana tabacum L.) exhibit rapid cell expansion that is sensitive to Al. Therefore, the effect of Al on changes in cytoplasmic free Ca concentration ([Ca2+]cyt) was followed in BY-2 cells to assess whether Al perturbed cellular Ca homeostasis. Al exposure resulted in a prolonged reduction in [Ca2+]cyt and inhibition of growth that was similar to the effect of the Ca2+ channel blocker La3+ and the Ca2+ chelator ethyleneglycol-bis(β-aminoethyl ether)-N,N′-tetraacetic acid. The Ca2+ channel blockers verapamil and nifedipine did not induce a decrease in [Ca2+]cyt in these cells and also failed to inhibit growth. Al and La3+, but not verapamil or nifedipine, reduced the rate of Mn2+ quenching of Indo-1 fluorescence, which is consistent with the blockage of Ca2+- and Mn2+-permeable channels. These results suggest that Al may act to block Ca2+ channels at the plasma membrane of plant cells and this action may play a crucial role in the phytotoxic activity of the Al ion.

Molecular phylogeny analysis of fiddler crabs: test of the hypothesis of increasing behavioral complexity in evolution.

The current phylogenetic hypothesis for the evolution and biogeography of fiddler crabs relies on the assumption that complex behavioral traits are assumed to also be evolutionary derived. Indo-west Pacific fiddler crabs have simpler reproductive social behavior and are more marine and were thought to be ancestral to the more behaviorally complex and more terrestrial American species. It was also hypothesized that the evolution of more complex social and reproductive behavior was associated with the colonization of the higher intertidal zones. Our phylogenetic analysis, based upon a set of independent molecular characters, however, demonstrates how widely entrenched ideas about evolution and biogeography led to a reasonable, but apparently incorrect, conclusion about the evolutionary trends within this pantropical group of crustaceans. Species bearing the set of "derived traits" are phylogenetically ancestral, suggesting an alternative evolutionary scenario: the evolution of reproductive behavioral complexity in fiddler crabs may have arisen multiple times during their evolution. The evolution of behavioral complexity may have arisen by coopting of a series of other adaptations for high intertidal living and antipredator escape. A calibration of rates of molecular evolution from populations on either side of the Isthmus of Panama suggest a sequence divergence rate for 16S rRNA of 0.9% per million years. The divergence between the ancestral clade and derived forms is estimated to be approximately 22 million years ago, whereas the divergence between the American and Indo-west Pacific is estimated to be approximately 17 million years ago.

Sphingosine: a mediator of acute renal tubular injury and subsequent cytoresistance.

The goal of this study was to determine whether sphingosine and ceramide, second messengers derived from sphingolipid breakdown, alter kidney proximal tubular cell viability and their adaptive responses to further damage. Adult human kidney proximal tubular (HK-2) cells were cultured for 0-20 hr in the presence or absence of sphingosine, sphingosine metabolites (sphingosine 1-phosphate, dimethylsphingosine), or C2, C8, or C16 ceramide. Acute cell injury was assessed by vital dye exclusion and tetrazolium dye transport. Their subsequent impact on superimposed ATP depletion/Ca2+ ionophore-induced damage was also assessed. Sphingosine (> or = 10 microM), sphingosine 1-phosphate, dimethylsphingosine, and selected ceramides (C2 and C8, but not C16) each induced rapid, dose-dependent cytotoxicity. This occurred in the absence of DNA laddering or morphologic changes of apoptosis, suggesting a necrotic form of cell death. Prolonged exposure (20 hr) to subtoxic sphingosine doses (< or = 7.5 microM) induced substantial cytoresistance to superimposed ATP depletion/Ca2+ ionophore-mediated damage. Conversely, neither short-term sphingosine treatment (< or = 8.5 hr) nor 20-hr exposures to any of the above sphingosine/ceramide derivatives/metabolites or various free fatty acids reproduced this effect. Sphingosine-induced cytoresistance was dissociated from the extent of cytosolic Ca2+ loading (indo-1 fluorescence), indicating a direct increase in cell resistance to attack. We conclude that sphingosine can exert dual effects on proximal renal tubular viability: in high concentrations it induces cell necrosis, whereas in low doses it initiates a cytoresistant state. These results could be reproduced in human foreskin fibroblasts, suggesting broad-based relevance to the area of acute cell injury and repair.

Genetics and the origin of European languages.

A new set of European genetic data has been analyzed to dissect independent patterns of geographic variation. The most important cause of European genetic variation has been confirmed to correspond to the migration of Neolithic farmers from the area of origin of agriculture in the Middle East. The next most important component of genetic variation is apparently associated with a north-south gradient possibly due to adaptation to cold climates but also to the differentiation of the Uralic and the Indo-European language-speaking people; however, the relevant correlations are not significantly different from zero after elimination of the spatial autocorrelation. The third component is highly correlated with the infiltration of the Yamna ("Kurgan") people, nomadic pastoralists who domesticated the horse and who have been claimed to have spread Indo-European languages to Europe; this association, which is statistically significant even when taking spatial autocorrelations into account, does not completely exclude the hypothesis of Indo-European as the language of Neolithic farmers. It is possible that both expansions were responsible for the spread of different subfamilies of Indo-European languages, but our genetic data cannot resolve their relative importance.

Interações moleculares no mecanismo de ação da galectina-4 humana

A galectina-4 humana (HGal-4), pertencente à família das galectinas, possui dois domínios de reconhecimento de carboidratos (CRDs) com alta afinidade para β-galactosídeos e se encontra amplamente distribuída em células normais e neoplásicas de diferentes organismos. Suas funções snglobam uma grande variedade de eventos celulares, tais como processos inflamatórios, neoplásicos, progressão tumoral e metástase. Entretanto, muitas perguntas sobre suas interações com diferentes carboidratos, a especificidade destas interações e o papel específico das galectinas permanecem ainda sem resposta. No presente trabalho, propomos a investigação das interações galectina-glicano da galectina-4 humana e de seus domínios CRDs independentes (CRD-I e CRD-II) através de um conjunto de métodos biofísicos. Através do método de dicroísmo circular (CD), usando várias regiões espectrais, e fluorescência fomos capazes de entender mudanças ocorrentes na estrutura secundária e terciária das protéinas quando da interação com lactose/sacarose. Estes dados, juntamente com testes de hemaglutinação, mostraram que a glectina-4 e os CRDs respondem de forma distinta à ligação com açúcar. Por diferentes técnicas (fluorescência, ITC e MST) determinamos as constantes de dissociação para os domínios CRDs (Kd ~0,5 mM) e para HGal-4 e, de forma qualitativa, os valores obtidos indicaram possíveis estados oligoméricos dessas proteínas. A investigação da interação proteína-membrana da HGal-4 foi feita, primeiramente, com miméticos de membranas e monitorada pela técnica de RPE em crescente complexidade de composição de tais miméticos, indo desde composições mais simples, passando por lipid rafts na presença de diferentes glicolipídeos (GM1, LPS) e chegando-se à interação com células tumorais (U87MG, T98G e HT-29). Tais experimentos mostraram que galectina-4 reconhece e se liga naqueles modelos onde existem glicanos complexos na superfície. Investigamos também a participação de HGal-4 endógena e exógena no tratamento quimioterápico de células tumorais e verificamos um papel importante de HGal-4 para células HT-29. Finalizando esta tese, apresentamos o trabalho realizado em um ano de estágio na University of Oxford, durante o qual, investigamos a estrutura da região C-terminal de um receptor da família GPCR, qual seja o receptor de neurotensina NTS1. Aqui, mais uma vez, foi empregada a técnica de RPE que aliada à produção/marcação de mutantes do receptor, permitiu determinar que a hélice H8 se estabiliza quando em proteolipossomos.