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Dozens of fresh active-layer detachments were observed on the Fosheim Peninsula in late-summer 2005 following one week of high air temperatures and nearly continuous bright sunshine. One of these shallow translational landslides started as a minor movement on an upper, steeper slope segment but over several days its front propagated 250 m downslope at velocities of 2–9 m h−1. A second, smaller active-layer detachment developed within less than 2 hours and subsequent movement was limited. Effective stress analyses can explain the initiation of these landslides on moderate gradients. Movements across extremely low-angled slope segments, however, likely require both dynamic loading from the moving mass and very low basal undrained shear strengths produced by high porewater pressures. The lengthy development of the large active-layer detachment helps explain stratigraphic and morphologic features previously observed in these slope failures. Copyright © 2007 John Wiley & Sons, Ltd.

As of 2003, the warmest year on record in Canada (and globally) was 1998. Extensive warming was observed over the Canadian Arctic during the summer of 1998. A collaborative, interdisciplinary project involving government, universities, and the private sector examined the effect of this unusual warmth on cryospheric conditions and documented the responses, placing them in a 30–40 year context. This paper represents a synthesis of these results. 1998 was characterized by a melt season of exceptional length, having both an unusually early start and late finish. Extremes were noted for cryospheric variables that included ground thaw penetration, snow‐free season, lake‐ice‐free season, glacier melt, and the duration and extent of marine open water. The warm conditions contributed to the break‐up of two long‐term, multi‐year ice plugs in the north‐west Canadian Arctic Archipelago, which allowed floe ice into the Northwest Passage. Synoptic events and preconditioning were observed to play an important r...

FGF-1 binds to and activates specific transmembrane receptors (FGFRs) and is subsequently internalized and translocated to the interior of the cell. To elucidate the role of the receptor in the translocation process, we studied the effects of the elimination of distinct sites of the ligand-receptor interaction. On the basis of the structure of the FGF-1-FGFR1 complex, we substituted four key amino acid residues of FGF-1 from the FGF-receptor binding site with alanines, constructing four point mutants and one double mutant. We determined by in vivo assays in NIH 3T3 cells the ability of the mutants to bind to specific FGF receptors, to stimulate DNA synthesis, and to activate downstream signaling pathways. We found that correct binding to the receptor is necessary for optimal stimulation of DNA synthesis. All four single mutants became phosphorylated to different extents, indicating that they were translocated to the cytosol/nucleus with varying efficiency. This indicates that despite a low affinity for FGFR, translocation to the cytosol/nucleus can still occur. However, simultaneous substitution in two of the positions led to a total loss of biological activity of the growth factor and prevented its internalization, implying that there is only one strongly receptor-dependent, productive way of translocating FGF-1. We also found that the process of translocation did not correlate with the thermal stability of the protein. Additionally, we observed a clear negative correlation between the stability of the FGF-1 mutants and the efficiency of their phosphorylation, which strongly suggests that protein kinases prefer the unfolded state of the protein substrate.

Members of the fibroblast growth factor family bind to one or more of the four closely related membrane-spanning FGF receptors. In addition to signaling through the receptors, exogenous FGF-1 and FGF-2 are endocytosed and translocated to the cytosol and nucleus where they stimulate RNA and DNA synthesis. Here we have studied the ability of the four FGF receptors to facilitate translocation of exogenous FGF-1 to the cytosol and nucleus. FGFR1 and FGFR4 were able to mediate translocation, whereas FGFR2 and FGFR3 completely lacked this ability. By analyzing mutant FGFRs we found that the tyrosine kinase domain could be deleted from FGFR1 without abolishing translocation, whereas the C-terminal tail of the FGFRs, constituted by approximately 50 amino acids downstream of the kinase domain, plays a crucial role in FGF-1 translocation. Three amino acids residues within the C-terminal tail were found to be of particular importance for translocation. For FGFR2, the two amino acid substitutions Q774M and P800H were sufficient to enable the receptor to support FGF-1 translocation. The results demonstrate a striking diversity in function of the four FGFRs determined by their C-terminal domain.

Active-layer detachment failures triggered weeks to months after forest fire in the central Mackenzie Valley (65°N, discontinuous permafrost zone) are compared to others generated almost immediately by summer meteorological conditions on the Fosheim Peninsula, Ellesmere Island (80°N, continuous permafrost zone). Preferred long-axis orientations in both zones vary in relation to valley geometry and ground ice distribution: differential insolation plays no direct role in detachment failure distribution. Rates of geomorphic work over periods of one to two centuries are of the same order of magnitude. Threshold meteorological conditions for initiating failures on the Fosheim Peninsula can be incorporated into a surface heating index, but pre-conditioning of the active layer remains important because rapid thaw does not always initiate activity. Slope pre-conditioning does not occur at the fire-affected sites because the failure zone is within formerly perennially frozen ground. Long-term rates of unit vertical transport at the most active site on the Fosheim Peninsula are similar to those due to debris flow and slushflow in a nearby mountain range. The frequency of potential triggering events at the Ellesmere Island sites is expected to increase if summer climate warms, providing low percentage cloud cover is maintained during periods of high air temperatures. Copyright © 2005 John Wiley & Sons, Ltd.

A turf-banked solifluction lobe was instrumented for the continuous recording of surface and internal movement, thaw settlement, soil volumetric moisture content and thermal conditions during the spring and summer of 2002. Strain probe measurements showed that gelifluction occurred as a series of discrete and abrupt displacements near the thaw plane, followed by retrograde movement. Most gelifluction events took place when thaw rates were high and the soil was saturated almost to the surface, but rain was also capable of inducing gelifluction at depth. The rapid and localized character of the observed displacements suggests that gelifluction results from micro-shearing of the soil, possibly along the interface of thawing ice lenses. Copyright © 2005 John Wiley & Sons, Ltd.

Fibroblast growth factor 1 is a powerful mitogen playing an important role in morphogenesis, angiogenesis and wound healing and is therefore of potential medical interest. Using homologous sequence and structure comparisons, we designed and constructed 16 mutants of FGF-1 with increased thermodynamic stability, as determined by chemical and heat denaturation. For multiple mutants, additive effects on stability were observed, providing mutants up to 7.8 degrees C more stable than the wild-type. None of the introduced mutations affected any FGF-1 biological activities, such as stimulation of DNA synthesis, MAP kinase activation and binding to the FGF receptor on the cell surface. Our study provides a good starting point to improve the stability of FGF-1 in the context of its wide potential therapeutic applications. We showed that a homology approach is an effective method to change the thermodynamic properties of the protein without altering its function.

The growth, longevity, and decay of mineral-cored palsas at an altitudinal treeline site in the southern Yukon all appear to be significantly affected by the activities of beaver (Castor canadensis). The palsas are composed of stratified, fine-grained, organic-rich, frost-susceptible deposits, which are interpreted as originating from sedimentation in beaver ponds. Peat development, which is a precondition for mound formation, takes place in the adjacent wetland, in part due to poor drainage because of dams. Palsa degradation over the past 55 yr preferentially followed flooding due to dam construction. Drainage of ponds by dam breach was succeeded by mound formation in aggrading permafrost. Unlike previous studies, therefore, it is impossible to infer a clear climate signal from palsa dynamics at this location.

The basal temperature of snow (BTS) method was used to predict the distribution of permafrost within a mountainous basin located in the southern Yukon Territory. A modelled BTS surface, based on several hundred measured values, was created within a Geographic Information System (GIS) environment using elevation and potential incoming solar radiation as independent variables. The distribution of frozen ground at 200 test sites was compared to the modelled BTS values using logistic regression. The resultant map of permafrost probability shows that all four conventional permafrost distribution classes (isolated patches, scattered and widespread discontinuous permafrost, and continuous permafrost) are present within the basin. Supplementary logistic regression analyses reveal that at certain elevations and aspects, the probability of permafrost occurrence varies markedly over short distances in response to snowpack depth. They also show that widespread alterations in snow cover would be expected to substantially affect permafrost distribution even if air temperatures were to remain unchanged. Copyright © 2004 John Wiley & Sons, Ltd.

Steroid hormones in plants and in animals are very important for physiological and developmental regulation. In animals steroid hormones are recognized by nuclear receptors, which transcriptionally regulate specific target genes following binding of the ligand. In addition, numerous rapid effects generated by steroids appear to be mediated by a mechanism not depending on the activation of nuclear receptors. Although the existence of separate membrane receptors was postulated many years ago and hundreds of reports supporting this hypothesis have been published, no animal membrane steroid receptor has been cloned to date. Meanwhile, a plant steroid receptor from Arabidopsis thaliana has been identified and cloned. It is a transmembrane protein which specifically recognizes plant steroids (brassinosteroids) at the cell surface and has a serine/threonine protein kinase activity. It seems that plants have no intracellular steroid receptors, since there are no genes homologous to the family of animal nuclear steroid receptors in the genome of A. thaliana. Since the reason of the rapid responses to steroid hormones in animal cells still remains obscure we show in this article two possible explanations of this phenomenon. Using 1,25-dihydroxyvitamin D(3) as an example of animal steroid hormone, we review results of our and of other groups concordant with the hypothesis of membrane steroid receptors. We also review the results of experiments performed with ovarian hormones, that led their authors to the hypothesis explaining rapid steroid actions without distinct membrane steroid receptors. Finally, examples of polypeptide growth factor that similarly to steroids exhibit a dual mode of action, activating not only cell surface receptors, but also intracellular targets, are discussed.

The expression of protein tyrosine phosphatase epsilon (PTPe) was studied in human tissues and blood cells. High mRNA expression was observed in peripheral blood leucocytes, particularly in monocytes and granulocytes which revealed at least four distinct transcripts. In lymphocytes, PTPe expression was induced after 12-O-tetradecanoylphorbol-13-acetate (TPA) or antigen-receptor stimulation, indicating that PTPe plays a role in the events taking place after antigen engagement. Previously, PTPe has been shown to be involved in regulating voltage-gated potassium channel activity, insulin-receptor signalling and Janus kinase-signal transducers and activators of transcription (STAT) signalling. Transfection of cells with different PTPe constructs and activator protein-1 reporter gene indicates that the catalytic activity of PTPe is involved in the regulation of the mitogen-activated protein kinase cascade. In particular, the extracellular signal-regulated kinases (ERK1/2) were shown to be inhibited in both phosphorylation status and enzymatic activity after overexpression of PTPe. Thus, PTPe emerges as a phosphatase with a potential to regulate the ERK1/2 pathway either directly or indirectly through its catalytic activity.

Surface wash erosion was measured at runoff plots on low to moderate slopes in clayey and sandy silts underlain by continuous permafrost on the Fosheim Peninsula, Ellesmere Island. Due to snow redistribution in winter, total precipitation on the plots varied from 34 to 150 mm, with corresponding surface runoff values of 0 to 102 mm. Where runoff occurred, at least 80% of it was derived from snowmelt. Suspended sediment removal was Plot data (precipitation, vegetation and surface grain-size) from the Fosheim Peninsula and Banks Island were used to develop a statistical model of suspended sediment removal by surface wash on undisturbed slopes. For any given grain-size, the model predicts a rise in erosion from zero precipitation (because of an absence of runoff) to a peak at about 50 mm, a decline as precipitation increases to 300 mm and a further increase in erosion beyond this inflection point. This non-linear response is due to the complex interaction of moisture (primarily snow) and vegetation cover. Erosion at any given precipitation value varies through three orders of magnitude depending on surface grain-size. The maximum erosion predicted is 1 kg m−2 a−1 for a runoff plot with 1100 mm of precipitation, a corresponding vegetation cover of 77% and a median surface grain-size of 7 φ.

Measurements of turf-banked solifluction lobes at a site in the Kluane Range, Yukon Territory, are compared to observations made by L.W. Price of similar features located 50 km to the north in the Ruby Range. Both studies show that a threshold depth of snow is necessary for lobes to develop. The relative importance of solifluction on slopes with different orientations, however, is not congruent. The largest lobes at our site are present on northeast-facing slopes and the smallest on northwest-facing slopes. Lobe dimensions increase downslope in association with a greater organic mat thickness, a higher soil fines content, and a reduced late-summer thaw depth. Riser heights that are large relative to tread length-to-width ratios are correlated with a thin organic mat, a thick active layer and a high coarse particle content. The lobe plan-form, described by the ratio of tread length to tread width, is significantly correlated with only one biophysical variable. Mean and median length-to-width ratios are below unity for all aspects at our site and in several other studies, suggesting a common evolutionary form. A cycle of solifluction lobe development is proposed, in which a lobe enlarges to a maximum size that depends on micro-site environmental characteristics. Copyright © 2002 John Wiley & Sons, Ltd.

Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson's tumor, is a rare nonneoplastic vascular lesion caused by the abnormal proliferation of endothelial cells. Clinically and radiologically, IPEH presents as a soft tissue mass that may simulate and be mistaken for a sarcomatous tumor. There have been reports of this entity involving the skin or subcutaneous tissues in normal blood vessels and vascular malformations. Herein, we present the first reported case of Masson's tumor arising from an arteriovenous hemodialysis fistula. We emphasize the imaging features of this lesion and briefly discuss its pathophysiology.

Near-surface rock temperatures were recorded hourly for more than one year around a sandstone tor located on a ridge-crest at an elevation of 270 m asl. There were significant differences between air and rock temperatures except during the polar night. The SSE- and WSW-facing sides experienced large amplitude diurnal temperature cycles in the late-winter and spring, and these crossed through 0 °C from mid-April to May, well before air temperatures rose above freezing. Rock temperatures at a depth of 15 mm on the SSE-face exceeded air temperature by up to 31 °C. During most of the summer, rock faces and air temperatures remained above 0 °C. Diurnal temperature cycles were smaller in amplitude in the autumn and few cycles through 0 °C were measured because of persistent cloud cover and the absence of a radiation-reflecting snowpack. Modelling using a constant environmental lapse rate shows that although the timing and number of temperature cycles through 0 °C are influenced by altitude, the importance of rock-face orientation on the relative numbers of cycles is independent of tor elevation. The average rate of micro-weathering measured on several tors over four years was 0.012 mm a−1. No loss of larger clasts was observed at the monitored tor over 11 years suggesting that the combined rate of all types of weathering is low. Copyright © 2001 John Wiley & Sons, Ltd. RESUME Tout autour d'un tor de gres localise sur une crete etroite a une altitude de 270 m, la temperature de la roche pres de la surface a ete enregistree toutes les heures pendant plus d'un an. Des differences significatives entre les temperatures de l'air et de la roche ont ete observees sauf pendant la nuit polaire. Les faces SSE et WSW ont montre les plus grands cycles de temperature diurnes a la fin de l'hiver et au printemps et la temperature de 0°C a ete franchie de la mi-avril jusqu'en mai, bien avant que les temperatures de l'air ne s'elevent au-dessus du gel. Les temperatures de la roche a une profondeur de 15 mm sur la face SSE ont depasse la temperature de l'air de plus de 31°C. Pendant la plus grande partie de l'ete, les temperatures des faces rocheuses et de l'air sont restees au-dessus de 0°C. L'amplitude des cycles diurnes de temperature a ete plus petite en automne et peu de cycles franchissant 0°C ont ete mesures du fait de la couverture persistante de nuages et de l'absence de neige reflechissant la radiation. Un modele utilisant un espace de temps constant a montre que bien que le moment et le nombre de cycles de temperature franchissant 0°C soit influence par l'altitude, l'importance de l'orientation de la face rocheuse sur le nombre de cycles relatifs est independant de l'altitude du tor. La vitesse moyenne de la micro-alteration mesuree sur plusieurs tors en quatre ans a ete de 0.012 mm a−1. Aucun detachement de bloc pendant 11 ans n'a ete observe sur le tor etudie, suggerant que la vitesse combinee de tous les types d'alteration est faible. Copyright © 2001 John Wiley & Sons, Ltd.

Endocytic uptake and intracellular transport of acidic fibroblast growth factor (aFGF) was studied in cells transfected with FGF receptor 4 with mutations in the cytoplasmic part. Endocytic uptake in HeLa cells was reduced but not abolished when the tyrosine kinase of the receptor was inactivated by mutations or deletions. The tyrosine kinase-dependent endocytosis of aFGF was prevented by the expression of a dominant negative dynamin mutant that blocks endocytosis from coated pits and caveolae. However, more than half of the total endocytic uptake of aFGF was not affected under these conditions, indicating an endocytic uptake mechanism not involving coated pits or caveolae. Mutation or deletion of a putative caveolin-binding sequence did not prevent the localization of part of the receptors to a low density, caveolin-containing subcellular fraction. Whereas wild-type receptor transfers the growth factor from early endosomes to the recycling compartment, kinase negative, full length receptors were inefficient in this respect and the growth factor instead accumulated in lysosomes. By contrast, when most of the intracellular part of the receptor, including the kinase domain, was removed, aFGF was transported to the recycling compartment, as in cells that express wild-type receptors, suggesting the presence of a kinase-regulated targeting signal in the cytoplasmic tail.

A new mRNA coding for the heparin-binding EGF-like growth factor (HB-EGF) was found in Vero cells. The corresponding cDNA had C-156 in place of T, which resulted in a loss of the NheI site and replacement of Leu-33 with Pro in the HB-EGF precursor. The known and new forms of the precursor were accordingly termed L and P. A conformational change in the corresponding propeptide region was assumed to affect the processing of soluble secreted HB-EGF. The L and P mRNAs are differently expressed in various cell lines, have identical 5"-untranslated sequences, and are probably transcribed from one promoter and then alternatively spliced. Stimulation of resting Vero cells with tetraphorbol ester (TPA) substantially increased the production of the L form, decreased the production of the P form, and did not affect the expression of total HB-EGF mRNA. This was associated with increased binding of the diphtheria toxin, suggesting that the L HB-EGF precursor acts as its receptor.

The paper investigates the effect of associational membership on trustworthiness by using panel data at a regional level. The proxy of trustworthiness is based on indicators of opportunistic behaviour in a cooperative framework. This proxy is analysed in relation to many socio-economic variables, in particular focusing on different types of horizontal associations usually considered as «Putnam groups»: A) cultural; b) ecological, human rights and peace and c) volunteer. The paper shows that: i) volunteer associations positively affect the level of trustworthiness; ii) cultural and ecological, human rights and peace associations have no positive effects on trustworthiness. On the contrary, they show a negative (even though only in some model specifications significant) correlation to trustworthiness. Not all the associations usually considered «Putnam groups» seem to reflect the theoretical approach of this author. The analysis of the trustworthiness' determinants has important economic implications. The absence of opportunistic behaviour decreases transaction costs and promotes cooperation, positively affecting socio-economic development. The empirical analysis uses region fixed effects, random effects and instrumental variables to consider endogeneity problems and it is based on an original panel dataset collected by the author from existing national sources

Active-layer detachment slides are locally common on Fosheim Peninsula, Ellesmere Island, where permafrost is continuous, the active layer is 0.5-0.75 m thick, and summer temperatures are unusually high in comparison with much of the Canadian High Arctic. In this paper we report pore-water pressures at the base of the active layer, recorded in situ on two slopes in late July and early August 1995. These data form the basis for slope stability analyses based on effective stress conditions. During fieldwork, the factor of safety within an old detachment slide on a slope at Hot Weather Creek was slightly greater than unity. At "Big Slide Creek," on a slope showing no evidence of earlier detachment failures, the factor of safety was less than unity on a steep basal slope section but greater than unity elsewhere. In the upper slope, pore-water pressures were only just subcritical. Sensitivity analyses demonstrate that the stability of the shallow active layer is strongly influenced by changes in soil shear strength. Possible mechanisms for reduction in shear strength through time include weathering of soils and gradual increases in basal active layer ice content. However, we suggest here that soil shearing during annual gelifluction movements is most likely to progressively reduce shear strengths at the base of the active layer from peak values to close to residual, facilitating the triggering of active-layer detachment failures.Key words: detachment slides, Ellesmere Island, pore-water pressures, gelifluction.

L'objectif de cette etude est de determiner le potentiel de l'utilisation des images panchromatiques SPOT a 10 m de resolution pour detecter et identifier les caracteristiques indicatrices de pergelisol pour 16 sites sur l'Ile Ellesmere. Une image satellite SPOT acquise au cours de l'ete 1990 a ete rehaussee numeriquement par etalement de contraste et comparee aux donnees de terrain et a des photographies aeriennes pour des localites du nord et du centre de la Peninsule Fosheim. La recherche montre que l'on peut utiliser les images SPOT dans cette region pour detecter : (1) de grands polygones delimites par des coins de glace avec centre bombe bien developpes et sureleves (d'un diametre de 30-60 m) et de grands polygones avec centre en depression parsemes d'etangs peu profonds, (2) des thermokarts d'origine anthropogenique 40 ans apres la perturbation originale de terrain; (3) des decrochements recents du mollisol de>500 m de long; et (4) des secteurs actifs de decollement par paquet dont on connaissait la presence anterieurement. L'application d'algorithmes de detection de contour a l'image SPOT a permis de delimiter des sols polygonaux sur certains sites. Toutefois, l'analyse d'image a ete limitee par la dimension des pixels en fonction de la dimension de ces caracteristiques et, dans un test a l'aveuglette sur des polygones de 10-15 m, on constate une sous-estimation significative des sols polygonaux.

FGF-1 stimulated DNA synthesis and induced expression of IL-2 receptors in the murine fibrosarcoma cell line, F69-3. Concomitant treatment with IL-2 abolished the stimulation of DNA synthesis, but not binding of FGF-1 to the FGF-receptors or subsequent endocytosis of the bound growth factor. Also, it did not inhibit activation of the FGF-receptor tyrosine kinase or stimulation of the downstream effector, MAP kinase. Treatment with IL-2 prevented transport of FGF-1 to the nuclear fraction in a time- and dose-dependent manner that parallelled the inhibition of FGF-1 stimulated DNA synthesis. The data support our earlier finding that transport of FGF-1 to the nucleus is an important event in the mechanism of stimulation of DNA synthesis induced by the growth factor, and they demonstrate that treatment with a cytokine can modulate the cellular response to FGF-1.

In a previous study, we have isolated and characterized cDNA encoding a novel `short form' of heparin-binding EGF-like growth factor (SF HB-EGF) ( Loukianov et al., 1997 ). In the present work, we have found that cDNA for SF HB-EGF and for full-length HB-EGF are each represented by two variants, which we refer to as L and P forms. The L form is the previously known form of HB-EGF cDNA and encodes a leucine in position 33. The P form described in this report, encodes a proline in codon 33. The L33P substitution is predicted to cause a significant alteration in the proregion structure of SF HB-EGF and HB-EGF.

Producción Científica, Acidic fibroblast growth factor (aFGF) is a potent mitogen. It acts through activation of specific cell surface receptors leading to intracellular tyrosine phosphorylation cascades, but several reports also indicate that aFGF enters cells and that it has an intracellular function as well. The aFGF(K132E) mutant binds to and activates fibroblast growth factor receptors equally strongly as the wild-type, but it is a poor mitogen. We demonstrate that aFGF(K132E) enters NIH 3T3 cells and is transported to the nuclear fraction like wild-type aFGF. A fusion protein of aFGF(K132E) and diphtheria toxin A-fragment (aFGF(K132E)-DT-A) and a similar fusion protein containing wild-type aFGF (aFGF-DT-A) were reconstituted with diphtheria toxin B-fragment. Both fusion proteins were translocated to the cytosol by the diphtheria toxin pathway and subsequently recovered from the nuclear fraction. Whereas translocation of aFGF-DT-A stimulated DNA synthesis in U2OSDR1 cells lacking functional fibroblast growth factor receptors, aFGF(K132E)-DT-A did not. The mutation disrupts a protein kinase C phosphorylation site in the growth factor making it unable to be phosphorylated. The data indicate that a defect in the intracellular action of aFGF(K132E) is the reason for its strongly reduced mitogenicity, possibly due to inability to be phosphorylated.

Northerly winds of 25 m s−1, and possibly in excess of 40 m s−1, occurred for about one hour in the Eureka area on 18 February 1991. In the valley of Black Top Creek, the effects of these winds were dominantly (1) deflation of fine sediments on north-east-facing slopes, leaving a patchy soil crust perched up to 28 mm above the surrounding surface, and (2) deposition of up to 125 mm of fine and coarse sediments over snow on south-west-facing slopes, particularly in rough microtopography within detachment slides. The importance of wind erosion in this arid environment was shown by surface soil loss on a north-east-facing slope of 4·8 kg m−2 (4 mm), an amount equivalent to more than 20 years of denudation by water. The maximum size (45 mm long) and weight (25 g) of particles transported during this storm demonstrate that aeolian transportation in the Canadian Arctic, like the Antarctic, is not confined to sand-sized materials. © 1998 John Wiley & Sons, Ltd. Des vents du nord de 25 m s−1, et probablement atteignant 40 m s−1, se sont exerces pendant une heure dans la region d'Eureka, la 18 fevrier 1991. Dans la vallee du Black Top Creek, ces vents ont entraine principalement 1) la deflation de sediments fins sur les pentes exposees au nord, laissant une croute de sol discontinue perchee a plus de 28 mm au-dessus de la surface voisine, et 2) le depot de plus de 125 mm de sediments fins et grossiers au dessus de la neige sur les pentes exposees au sud-ouest, surtout lorsque la microtopographie etait rugueuse. L'importance de l'erosion eolienne dans cet environnement aride est montree par une perte du sol de 4,8 Kg/m2 (4 mm) sur la pente exposee au nord, ce qui represente un total equivalent a plus de 20 ans de denudation par l'eau courante. La taille maximum (45 mm) et le poids (25 g) des particules transportees pendant cette tempete, demontrent que le transport eolien dans l'arctique comme dans l'antarctique, n'est pas seulement confine aux materiaux de granulometrie sableuse. © 1998 John Wiley & Sons, Ltd.

Widespread clastic deposits, 80n1800 m long, on the eastern side of the Sawtooth Range are the result of debris flow and slushflow. Small hillslope debris flows (10n10 3 m 3 ), originating on talus slopes at the mountain front and not associated with preexisting gullies, and large channelized debris flows (10 3 n10 4 m 3 ), debouching from basins within the mountains, are comparable morphologically to those in other high-latitude and high-altitude environments. Channelized deposits are often modified by the effects of slushflow and fluvial activity. Provisional lichen growth curves for the area were produced by correlation of thallus size with the enlargement of ice-wedge polygon troughs. Lichenometry and aerial photograph interpretation were used to estimate the age of deposits so that event frequencies and rates of geomorphic work could be calculated. Vertical transport by rapid mass movements during the 20th Century averaged 17 × 10 3 Mg·m·a n1 ·km n2 (± half an order of magnitude), corresponding to a rock denudation rate of 0.05 mm·a n1 for the basins and peaks feeding the east-facing slopes. Channelized debris flow produced more than 70% of this transport. Several of these large flows occurred in each of the three periods of 30n35 years examined, so their recurrence intervals are substantially shorter than values reported from locations in northern Scandinavia and Spitzbergen. Resume : Les dOpUts clastiques largement rOpandus, 80 ‡ 1800 m de longueur, sur le versant oriental du chaOnon Sawtooth, sont le rOsultat diOvnements de coulOes de dObris et de coulOes de bouillie neigeuse. De petites coulOes de dObris sur le versant (10n10 3 m 3 ), engendrOes sur les pentes de talus au front des montagnes et sans Œtre associOes ‡ des ravins prOexistants, et de volumineuses coulOes de dObris chenalisOes (10 3 n10 4 m 3 ) qui ont OtO OvacuOes des bassins localisOs ‡ liintOrieur des montagnes, sont morphologiquement comparables ‡ celles formOes en milieux de haute latitude et haute altitude. Les dOpUts chenalisOs sont frOquemment modifiOs par les effets crOOs par les coulOes de bouillie neigeuse et par liactivitO fluviale. Les courbes provisionnelles de croissance des lichens pour la rOgion ont OtO OlaborOes sur la base diune corrOlation de la dimension du thalle avec liOlargissement des fentes de polygones formOes par les coins de glace. La lichOnomOtrie et liinterprOtation de photos aOriennes ont OtO utilisOes pour Ovaluer li‚ge des dOpUts, et ainsi il a OtO possible de calculer les

Producción Científica, Acidic fibroblast growth factor (aFGF) binds to specific transmembrane receptors and is partly transported to a nuclear location. To study this transport we made a kinase-negative mutant of FGF receptor 4 as well as one where the major part of the cytoplasmic receptor domain was deleted, and expressed them in U2OSDr1 cells that lack functional FGF receptors. All receptors mediated endocytic uptake of aFGF. Translocation of the growth factor across cellular membranes was assayed using aFGF with a C-terminal CAAX-motif, which signals addition of a farnesyl group onto the protein once in the cytosol. CAAX-tagged aFGF was farnesylated when incubated with cells containing wild-type or kinase-negative receptors. It was not farnesylated in cells expressing the deleted receptor, or when the incubation was in the presence of genistein. aFGF incubated with cells transfected with wild-type or kinase-negative receptors, but not with the deleted receptor, was partly recovered from the nuclear fraction in the absence, but not in the presence of genistein. The data indicate that the cytoplasmic receptor domain, but not the active kinase, is required for transport of the growth factor into cells, and that genistein inhibits the process., Ministerio de Educación y Formación Profesional - Unión Europea (grant ERB4001GT954487)