Satellite telemetry of the winter migration of Adélie penguins (Pygoscelis adeliae)

Adélie penguins (Pygoscelis adeliae), after breeding in Antarctica during the austral summer, undergo a winter migration before returning to the breeding grounds 8 months later. It is the major source of adult mortality, with about a quarter of them not returning. Here we describe the first attempt to track the winter migration of Adélie penguins using satellite telemetry. Transmitters were attached to two penguins on 16 February 1991 after their post-breeding moult at Cape Bird, Ross Island, Antarctica. Transmissions were received from one penguin (bird #1) for 4.4 months, during which time it travelled 2792.6 km from the rookery (nearly 1500 km straight-line distance). Transmissions were received from the other penguin (bird #2) for 2.5 months during which time it followed a path remarkably similar to that of bird #1. The penguins travelled northwards up the coast of Victoria Land, keeping within 100 km of the coast, rounding Cape Adare soon after 29 March and were midway between the Balleny Islands and the Antarctic coast on 3 May. Thereafter, the record from bird #1 shows that it travelled further westwards until, when opposite the Mastusevich Glacier Tongue of the Mastusevich Glacier, it turned due north and moved away from the coast. By 29 June, when transmissions ended, its progression had slowed and it was northwest of the Balleny Islands near a zone where pack ice covered 75% of the surface of the sea. Two novel points that arise from this study are: (1) that Adélie penguins from Cape Bird undergo winter migrations of not less than 5000 km, and (2) that they may be travelling to common overwinter feeding grounds.     

Maternal effects after sexual reproduction in Daphnia magna

In this study we investigated the relationship between maternalsize and size of ephippial hatchlings in Daphnia magna. We observedthat larger females produce larger ephippia; these larger ephippiahave a higher hatching probability, yield larger neonates, whichin turn yield larger adults, producing more eggs. We interpretthese observations as an explanation why older and larger femalesof D.magna continue to produce ephippia despite a higher predationrisk.     

ALS/FTD‐associated FUS activates GSK‐3β to disrupt the VAPB–PTPIP51 interaction and ER–mitochondria associations

Defective FUS metabolism is strongly associated with amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD), but the mechanisms linking FUS to disease are not properly understood. However, many of the functions disrupted in ALS/FTD are regulated by signalling between the endoplasmic reticulum (ER) and mitochondria. This signalling is facilitated by close physical associations between the two organelles that are mediated by binding of the integral ER protein VAPB to the outer mitochondrial membrane protein PTPIP51, which act as molecular scaffolds to tether the two organelles. Here, we show that FUS disrupts the VAPB–PTPIP51 interaction and ER–mitochondria associations. These disruptions are accompanied by perturbation of Ca²⁺ uptake by mitochondria following its release from ER stores, which is a physiological read‐out of ER–mitochondria contacts. We also demonstrate that mitochondrial ATP production is impaired in FUS‐expressing cells; mitochondrial ATP production is linked to Ca²⁺ levels. Finally, we demonstrate that the FUS‐induced reductions to ER–mitochondria associations and are linked to activation of glycogen synthase kinase‐3β (GSK‐3β), a kinase already strongly associated with ALS/FTD.     

Age related decline in functional T cell subsets in the mouse

The changes of two functions of regulatory T cells in mice of different ages were determined. Mice were immunized with SRBC. DTH responsiveness of spleen cells and the production of IL-2 after Concanavalin A stimulation of the same cell suspension was measured. Cell populations were analysed for expression of Lyt-2 and Thy-1 surface markers. The relationship between DTH responsiveness and T cell subset distribution in peripheral blood was analysed. A direct relationship between age related changes in DTH responsiveness and T cell subset distributions in peripheral blood was observed in most individual animals.     

Lidocaine block of cardiac sodium channels

Lidocaine block of cardiac sodium channels was studied in voltage-clamped rabbit purkinje fibers at drug concentrations ranging from 1 mM down to effective antiarrhythmic doses (5-20 μM). Dose-response curves indicated that lidocaine blocks the channel by binding one-to-one, with a voltage-dependent K(d). The half-blocking concentration varied from more than 300 μM, at a negative holding potential where inactivation was completely removed, to approximately 10 μM, at a depolarized holding potential where inactivation was nearly complete. Lidocaine block showed prominent use dependence with trains of depolarizing pulses from a negative holding potential. During the interval between pulses, repriming of I (Na) displayed two exponential components, a normally recovering component (τless than 0.2 s), and a lidocaine-induced, slowly recovering fraction (τ approximately 1-2 s at pH 7.0). Raising the lidocaine concentration magnified the slowly recovering fraction without changing its time course; after a long depolarization, this fraction was one-half at approximately 10 μM lidocaine, just as expected if it corresponded to drug-bound, inactivated channels. At less than or equal to 20 μM lidocaine, the slowly recovering fraction grew exponentially to a steady level as the preceding depolarization was prolonged; the time course was the same for strong or weak depolarizations, that is, with or without significant activation of I(Na). This argues that use dependence at therapeutic levels reflects block of inactivated channels, rather than block of open channels. Overall, these results provide direct evidence for the “modulated-receptor hypothesis” of Hille (1977) and Hondeghem and Katzung (1977). Unlike tetrodotoxin, lidocaine shows similar interactions with Na channels of heart, nerve, and skeletal muscle.     

Evidence for the presence of the trimannosyl-di-N-acetyl-chitobiose core in the carbohydrate chains of human-parotid,proline-rich glycoprotein

The carbohydrate chains of the human-parotid, proline-rich glycoprotein are linked through a single type of carbohydrate-peptide linkage (asparaginyl-N-acetyl-glucosamine). The structure of the internal part of the carbohydrate chains, determined by chemical, enzymic, and g.l.c.-m.s. methods, includes the trimannosyl-di-N-acetylchitobiose core involved in the carbohydrate-peptide linkage. Furthermore, an L-fucose residue is linked to the 2-acetamido-2-deoxy-d-glucosyl residue linked to the L-asparaginyl residue. The sequence of the peripheral part of the chains has also been determined as α-L-Fucp→β-d-Galp→β-d-GlcpNAc→α-d-Manp, suggesting a double-branched, basic carbohydrate structure.     

Isolation and characterization of human urinary colony-stimulating factor

CSF-1 was isolated from a large volume of human normal urine (10,000 l), using the following 5 stages of purification: concentration by dialysis, silica gel adsorption, hydrophobic chromatography on phenyl-Sepharose CL-6B, fast protein liquid chromatography (FPLC) and finally preparative electrophoresis on polyacrylamide gels. We have isolated 8 mg of purified CSF-1 which migrated as a single band under non-reducing conditions in SDS-PAGE (staining with Coomassie Blue and the sensitive silver techniques). But in the presence of dithiothreitol, the SDS-PAGE pattern revealed a minor second band with a molecular mass of 50,000 Da. CSF-1 was purified 100,000-fold and has a specific activity of 2.16 X 10(7) units/mg protein. Its apparent molecular mass is 57,000 Da with an isoelectric point, pI = 5.8-6.0. The amino-acid composition is reported and compared with that of murine CSF-1. The carbohydrate content (sialic acid, sulphate groups, N-acetylglucosamine, N-acetylgalactosamine) was also determined, and it shows that CSF is a glycoprotein.     

Effects of essential fatty acids on the reproduction of a generalist herbivore

We studied direct and indirect effects of essential fatty acids(EFA) on Daphnia magna reproduction. Daphnia females that receivedEFA enriched algae over their entire lifespan produced largerbroods than females fed control algae. However, EFA-enrichedfemales were also 91% heavier than control females, which potentiallyexplain the larger investment in reproduction. Thus, with sucha large difference in female mass, it is difficult to differentiatethe direct effect of the EFA addition from the indirect (maternalsize) effects on reproduction. To assess the direct effectson reproduction, we performed two experiments in which we enrichedfemale diets with a range of fatty acids. To minimize maternalsize differences, we applied the EFA enrichments only to maturedaphniids and studied the effects on reproduction during andafter two time intervals (15–16 and 7 days). Limitingthe enrichment phase until after maturity decreased the maternalsize differences over the enrichment phase among the fatty acidtreatments from an average of 91% (for life time enrichment)to 29% after 15–16 days maternal enrichment interval,to 18% after the 7 day interval. Minimizing size differencesbetween differently enriched females decreased the differencesin brood size and offspring size. Neonates from control femaleswere more severely affected by starvation than offspring fromfemales that received saturated and polyunsaturated fatty acidenrichments. Under low food concentrations, only neonates thathad access to polyunsaturated fatty acids had positive growthrates, thus showing that although dietary fatty acids can beused for energy purposes, specific fatty acids are requiredto build new biomass. One consequence of our findings is thatoffspring size does not serve as a good estimate of offspringquality when feeding on different resource qualities.     

Fixation of cryo-sections under HIV-1 inactivating conditions: integrity of antigen binding sites and cell surface antigens

Cryostat-sections of biopsies from HIV-infected patients or HIV/SIV-infected experimental animals pose a biohazard risk to laboratory workers. The objective of this study was to select a procedure that appropriately fixes cryo-sections and reduces the risk of HIV-1 infectivity. This inactivation procedure should preserve antigen binding capacity of host-produced antibodies and the antigenic structure of epitopes present in these tissues, while retaining sufficient morphologic detail. We tested the effect of seven different established fixation-inactivation procedures for HIV-1 on the detection of specific antibodies and membrane markers, compared to acetone fixation as a reference. Frozen sections of spleens from mice immunized with trinitrophenyl (TNP)-Ficoll were incubated with TNP-alkaline phosphatase to detect specific antibody-forming cells and follicular immune complexes containing TNP-specific antibodies. In addition, sections were stained with monoclonal antibodies directed against IgM (187-1), T-cells (anti Thy-1), and marginal metallophilic macrophages (MOMA-1). Five procedures proved useful as they gave results similar to regular acetone fixation. In contrast, two procedures with a methanol-containing fixative obscured both antigen binding sites and membrane antigens. Subsequently, these five selected procedures were tested on glass slide preparations of HIV-1 infected cell lines, expressing HIV-1 determinants defined by monoclonal antibodies. Finally, the procedures were tested on sections of an HIV-1 infected human lymph node, for detection of HIV-specific B-cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Selection strategies for improved biocatalysts

Enzymes have become an attractive alternative to conventional catalysts in numerous industrial processes. However, their properties do not always meet the criteria of the application of interest. Directed evolution is a powerful tool for adopting the characteristics of an enzyme. However, selection of the evolved variants is a critical step, and therefore new strategies to enable selection of the desired enzymatic activity have been developed. This review focuses on these novel strategies for selecting enzymes from large libraries, in particular those that are used in the synthesis of pharmaceutical intermediates and pharmaceuticals.