Tyrosine phosphorylation in human lymphomas

In a previous study, we showed that the high level of protein tyrosine phosphorylation present in lymphomas containing an anaplastic lymphoma kinase (ALK) can be demonstrated in routinely processed paraffin tissue sections using immunolabelling techniques. In the present study we investigated whether oncogenic tyrosine kinase activation also occurs in other categories of lymphoma by staining 145 cases of lymphoma covering those tumours with a range of different subtypes including those with morphological similarity to ALK-positive anaplastic large cell lymphoma (ALCL). Twelve cases of the borderline malignant disorder lymphomatoid papulosis were also studied. Twenty seven of the 28 cases of ALK-positive ALCL showed the extensive cytoplasmic labelling for phosphotyrosine in the neoplastic cells. The remaining case containing moesin-ALK exhibited membrane-associated phosphotyrosine expression. There was no nuclear phosphotyrosine labelling in any of the ALK-positive ALCL, even though ALK was present within the cell nuclei in 23 of the tumours. Variable degrees of phosphotyrosine labelling, usually membrane-restricted, were observed in 7/40 cases of ALK-negative ALCL, 9/29 cases of diffuse large B-cell lymphoma, 3/6 cases of mediastinal B-cell lymphoma, 2/7 cases of Hodgkin's lymphoma, 3/6 cases of peripheral T-cell lymphomas unspecified, 4/6 cases of B-cell chronic lymphocytic leukaemia, 2/6 cases of follicular lymphomas and 2/12 cases of lymphomatoid papulosis studied. However none of these phosphotyrosine-positive cases showed the strong cytoplasmic labelling comparable to that seen in ALK-positive lymphoma. We conclude that activation of a tyrosine kinase is probably not a major oncogenic event in lymphomas other than ALK-positive ALCL.     

Dissociation between skeletal muscle microvascular PO2 and hypoxia-induced microvascular inflammation.

Systemic hypoxia (SHx) produces microvascular inflammation in mesenteric, cremasteric, and pial microcirculations. In anesthetized rats, SHx lowers arterial blood pressure (MABP), which may alter microvascular blood flow and microvascular Po(2) (Pm(O(2))) and influence SHx-induced leukocyte-endothelial adherence (LEA). These experiments attempted to determine the individual contributions of the decreases in Pm(O(2)), venular blood flow and shear rate, and MABP to the hypoxia-induced increase in LEA. Cremaster microcirculation of anesthetized rats was visualized by intravital microscopy. Pm(O(2)) was measured by a phosphorescence-quenching method. SHx [inspired Po(2) of 70 Torr for 10 min, MABP of 65 +/- 3 mmHg, arterial Po(2) (Pa(O(2))) of 33 +/- 1 Torr] and cremaster ischemia (MABP of 111 +/- 7 mmHg, Pa(O(2)) of 86 +/- 3 Torr) produced similar Pm(O(2)): 7 +/- 2 and 6 +/- 2 Torr, respectively. However, LEA increased only in SHx (1.9 +/- 0.9 vs. 11.2 +/- 1.1 leukocytes/100 microm, control vs. SHx, P < 0.05). Phentolamine-induced hypotension (MABP of 55 +/- 4 mmHg) in normoxia lowered Pm(O(2)) to 26 +/- 6 Torr but did not increase LEA. Cremaster equilibration with 95% N(2)-5% CO(2) during air breathing (Pa(O(2)) of 80 +/- 1 Torr) lowered Pm(O(2)) to 6 +/- 1 Torr but did not increase LEA. On the other hand, when cremaster Pm(O(2)) was maintained at 60-70 Torr during SHx (Pa(O(2)) of 35 +/- 1 Torr), LEA increased from 2.1 +/- 1.1 to 11.1 +/- 1.5 leukocytes/100 microm (P < 0.05). The results show a dissociation between Pm(O(2)) and LEA and support the idea that SHx results in the release of a mediator responsible for the inflammatory response.     

Mesenteric microvascular inflammatory responses to systemic hypoxia are mediated by PAF and LTB4.

Systemic hypoxia produces a rapid microvascular inflammatory response characterized by increased reactive oxygen species (ROS) levels, leukocyte-endothelial adherence and emigration, and increased vascular permeability. The lipid inflammatory mediator leukotriene B(4) (LTB(4)) is involved in the early hypoxia-induced responses (ROS generation and leukocyte adherence). Whether other lipid inflammatory mediators participate in this phenomenon is not known. The objective of these experiments was to study the role of platelet-activating factor (PAF) in the microvascular inflammatory response to hypoxia and its potential interactions with LTB(4) in this response. Intravital microscopy was used to examine mesenteric venules of anesthetized rats. We found that WEB-2086, a PAF receptor antagonist, completely prevented the increase in ROS levels and leukocyte adherence during a brief reduction in inspired Po(2) to anesthetized rats; administration of either WEB-2086 or the LTB(4) antagonist LTB(4)-DMA attenuated leukocyte emigration and the increase in vascular permeability to the same extent during prolonged systemic hypoxia in conscious rats. Furthermore, no additive effect was observed in either response when both antagonists were administered simultaneously. This study demonstrates a role for PAF in the rapid microvascular inflammatory response to hypoxia, as well as contributions of PAF and LTB(4) to the slowly developing responses observed during sustained hypoxia. The incomplete blockade of the hypoxia-induced increases in vascular permeability and leukocyte emigration by combined administration of both antagonists indicates that factors in addition to LTB(4) and PAF participate in these phenomena.     

The response of perennial and temporary headwater stream invertebrate communities to hydrological extremes

The headwaters of karst rivers experience considerable hydrological variability, including spates and streambed drying. Extreme summer flooding on the River Lathkill (Derbyshire, UK) provided the opportunity to examine the invertebrate community response to unseasonal spate flows, flow recession and, at temporary sites, streambed drying. Invertebrates were sampled at sites with differing flow permanence regimes during and after the spates. Following streambed drying at temporary sites, dewatered surface sediments were investigated as a refugium for aquatic invertebrates. Experimental rehydration of these dewatered sediments was conducted to promote development of desiccation-tolerant life stages. At perennial sites, spate flows reduced invertebrate abundance and diversity, whilst at temporary sites, flow reactivation facilitated rapid colonisation of the surface channel by a limited number of invertebrate taxa. Following streambed drying, 38 taxa were recorded from the dewatered and rehydrated sediments, with Oligochaeta being the most abundant taxon and Chironomidae (Diptera) the most diverse. Experimental rehydration of dewatered sediments revealed the presence of additional taxa, including Stenophylax sp. (Trichoptera: Limnephilidae) and Nemoura sp. (Plecoptera: Nemouridae). The influence of flow permanence on invertebrate community composition was apparent despite the aseasonal high-magnitude flood events. Flow permanence was also critical in determining the community response to the spate flows. Following streambed drying at temporary sites, the surficial sediments overlying the karstic bedrock functioned as an effective refugium for several taxa. The development of aquatic insects following experimental rehydration indicated that these taxa survived in dewatered sediments as desiccation-resistant eggs. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: Sonja Stendera     

TEP on the tide in killifish (<Emphasis Type="Italic">Fundulus heteroclitus</Emphasis>): effects of progressively changing salinity and prior acclimation to intermediate or cycling salinity

Transepithelial potentials (TEP) were measured in killifish, acclimated to freshwater (FW), seawater (SW), 33% SW or cycling salinities relevant to tidal cycles in an estuary, and subsequently subjected to salinity changes in progressive or random order. Random compared to progressive salinity changes in an upward or downward direction in FW- and SW-acclimated fish, respectively, did not greatly influence responses to salinity change. Fish acclimated to SW or 33% SW as well as those acclimated to cycling salinities behaved similarly (TEP more positive than +15 mV in 100% SW, decreasing to ~0 mV at 20–40% SW, and more negative than −30 mV in FW). In contrast, FW-acclimated fish displayed a less pronounced TEP response to salinity (0 mV in FW through 20% SW, increasing thereafter to values more positive than +10 mV at 100% SW). We conclude that when evaluated under estuarine tidal conditions, the killifish gill exhibits adaptive electrical characteristics, opposing Na⁺ loss at low salinity and favouring Na⁺ extrusion at high salinity, changes explained at least in part by the Cl⁻ to Na⁺ permeability ratio. Thus animals living in the estuaries can move to lower and higher salinities for short periods with little physiological disturbance, but this ability is lost after acclimation to FW.     

城市化对杭州市鸟类营巢集团的影响

为了了解城市化对鸟类营巢集团的影响,2007年3月至2007年8月,沿城市化梯度在杭州地区的城区、城乡结合区、农田区、农林交错区和自然林区等类型栖息地内设置3 000 m长、100 m宽的样线各18条,共计90条;并对其鸟类物种与群落营巢集团进行调查。调查共记录到繁殖鸟类96种,根据鸟类营巢位置可将其分为林冠枝干营巢集团、灌草丛营巢集团、林冠枝干/灌草丛营巢集团、自然洞穴营巢集团、人工建筑营巢集团、自然洞穴/人工建筑营巢集团地面营巢集团、水面营巢集团和寄生集团共9种。进一步分析显示,随城市化程度提高,鸟类营巢集团的数目呈整体下降趋势,而各集团的物种数也基本呈下降趋势。但是,不同的营巢集团对城市化的反应存在差异,导致其物种组成在群落中比例的明显变化。城市化程度的提高使树冠筑巢鸟、灌丛筑巢鸟、地面筑巢鸟及自然洞穴筑巢鸟在群落中所占的比例明显下降,其中地面筑巢鸟最为敏感,灌丛筑巢鸟次之。同时,自然洞穴/人工建筑集团的鸟类在群落中的比例却随着城市化程度的提高明显上升。各营巢集团之所以对城市化做出不同反应,是因为它们对筑巢地资源利用方式不同。此外,还发现植被盖度、人工设施面积、至市中心距离以及人为干扰等因素均可对鸟类营巢集团结构产生影响,但不同类型的营巢集团对上述因素的反应各异。     

Nutritional Ecology of <Emphasis Type="Italic">Ateles chamek</Emphasis> in lowland Bolivia: How Macronutrient Balancing Influences Food Choices

All free-living animals must make choices regarding which foods to eat, with the choices influencing their health and fitness. An important goal in nutritional ecology is therefore to understand what governs animals’ diet selection. Despite large variation in the availability of different food items, Peruvian spider monkeys (Ateles chamek) maintain a relatively stable daily protein intake, but allow total energy intake to vary as a function of the composition of available food items. This is referred to as protein-dominated macronutrient balancing. Here we assess the influence of this nutritional strategy on daily and seasonal nutritional intakes, estimate the nutritional value of different foods, and interpret unusual food choices. We conducted continuous all-day observations of focal spider monkeys inhabiting a semideciduous forest in Bolivia. We recorded feeding events, collected foods, and analyzed their nutrient content. By using the Geometric Framework for nutrition, we show that individuals reached their daily end-point in nutrient space —balance between protein and nonprotein energy intake— by consuming nutritionally balanced foods or by alternating between nutritionally complementary foods. The macronutritionally balanced figs of Ficus boliviana were their primary staple food and therefore dominated their overall nutritional intake. Our results also demonstrate that spider monkeys consumed a diverse array of ripe fruits to overcome periods of fig scarcity rather than vice versa; they could obtain sufficient protein on a diet of pure fruit; and unripe figs constituted a nutritionally rewarding and reliable food resource. We hope that the approaches taken and the conclusions reached in this study will catalyze further inquiries into the nutritional ecology of frugivorous primates.     

The Upper Cretaceous belemnite <Emphasis Type="Italic">Praeactinocamax plenus</Emphasis> (Blainville, 1827) from Lower Saxony (Upper Cenomanian,northwest Germany) and its distribution pattern in Europe

Occurrences of the Upper Cenomanian (Upper Cretaceous) belemnite Praeactinocamax plenus from the plenus Bed of northwest Germany (Söhlde-Loges working quarry near Salzgitter, Lower Saxony) are documented and described for the first time on the basis of two in situ finds. The find horizon and its surrounding beds are re-evaluated in a sequence stratigraphical context. In contrast to the interpretations of other authors, the plenus Bed is seen as a pelagization event in a parasequence of transgressively stacked beds, delimited by two significant erosion surfaces below and above. The exclusive occurrence of P. plenus in the top part of the plenus Bed and its absence from the post-plenus Bed succession, in the equivalent of which (higher part of the Plenus Marls Member) it is very common in southern England (Anglo-Paris Basin), is explained by ecological factors in stratigraphically complete sections (intra-shelf depressions) and by gaps in the stratigraphic records in swell settings. The distribution pattern of P. plenus suggests a preference for nearshore settings and a demersal mode of life.     

Use of cell wall stress to characterize σ22 (AlgT/U) activation by regulated proteolysis and its regulon in Pseudomonas aeruginosa

MucA sequesters extracytoplasmic function (ECF) σ²² ( algT/U encoded) from target promoters including P algD for alginate biosynthesis. We have shown that cell wall stress (e.g. d -cycloserine) is a potent inducer of the algD operon. Here we showed that MucB, encoded by the algT-mucABCD operon, interacts with MucA in the sigma–sequestration complex. We hypothesized that AlgW protease (a DegS homologue) is activated by cell wall stress to cleave MucA and release σ²². When strain PAO1 was exposed to d -cycloserine, MucA was degraded within just 10 min, and σ²² was activated. However, in an algW mutant, MucA was stable with no increased σ²² activity. Studies on a yaeL mutant, defective in an RseP/YaeL homologue, suggest that YaeL protease cleaves MucA only after cleavage by AlgW. A defect in mucD , encoding a periplasmic HtrA/DegP homologue, caused MucA instability, suggesting MucD degrades cell wall stress signals. Overall, these data indicate that cell wall stress signals release σ²² by regulated intramembrane proteolysis (RIP). Microarray analyses identified genes of the early and late cell wall stress stimulon, which included genes for alginate production. The subset of genes in the σ²² regulon was then determined, which included gene products predicted to contribute to recovery from cell wall stress.