Migration patterns of dendritic cells in the mouse. Homing to T cell-dependent areas of spleen, and binding within marginal zone.

Using quantitative techniques we have shown elsewhere that dendritic cells (DC) migrate from blood into the spleen, under the control of T cells. Here we traced the localization of DC within the spleen and sought to explain the means by which they entered. DC were labeled with a fluorochrome, Hoescht 33342, and injected intravenously. Spleens were removed 3 or 24 h later and DC were visualized within particular areas that were defined by mAbs and FITC anti-Igs. At 3 h most DC were in the red pulp, whereas by 24 h the majority had homed to T-dependent areas of the white pulp and may have become interdigitating cells. Lymphoid DC, isolated from spleen and perhaps normally present in blood, may thus be a migratory stage distinct from the relatively fixed interdigitating cells. We also developed a frozen section assay to investigate the interaction of DC with various lymphoid elements. When DC were incubated on sections of spleen, at 37 degrees C but not at 4 degrees C they attached specifically within the marginal zone and did not bind to T areas; in contrast, macrophages attached only to red pulp and T cells did not bind specifically. However, DC did not bind to sections of mesenteric lymph node, whereas T cells localized in particular regions at 4 degrees C but not at 37 degrees C, probably the high endothelial venules. DC may thus express "homing receptors," similar to those of T cells, for certain endothelia. We propose that T cells can modify the vascular endothelium in certain areas to allow egress of DC from the bloodstream

Thiomicrospira arctica sp nov and Thiomicrospira psychrophila sp nov., psychrophilic, obligately chemolithoautotrophic, sulfur-oxidizing bacteria isolated from marine Arctic sediments

Two psychrophilic, chemolithoautotrophic, sulfur-oxidizing bacteria were isolated from marine Arctic sediments sampled off the coast of Svalbard with thiosulfate as the electron donor and CO(2) as carbon source. Comparative analysis of 16S rRNA gene sequences suggested that the novel strains, designated SVAL-D(T) and SVAL-E(T), represent members of the genus Thiomicrospira. Further genotypic (DNA-DNA relatedness, DNA G+C content) and phenotypic characterization revealed that the strains represent members of two novel species. Both organisms are obligately autotrophic and strictly aerobic. Nitrate was not used as an electron acceptor. Chemolithoautotrophic growth was observed with thiosulfate, tetrathionate and sulfur. The temperature limits for growth of both strains were between -2 degrees C and 20.8 degrees C, with optima of 11.5-13.2 degrees C (SVAL-E(T)) and 14.6-15.4 degrees C (SVAL-D(T)), which is about 13-15 degrees C lower than the optima of all other recognized Thiomicrospira species. The maximum growth rate on thiosulfate at 14 degrees C was 0.14 h(-1) for strain SVAL-E(T) and 0.2 h(-1) for strain SVAL-D(T). Major fatty acids of SVAL-D(T) are C(16 : 1), C(18 : 0) and C(16 : 0), and those of SVAL-E(T) are C(16 : 1), C(18 : 1), C(16 : 0) and C(14 : 1). Cells of SVAL-D(T) and SVAL-E(T) are rods, like those of their closest relatives. To our knowledge the novel strains are the first psychrophilic, chemolithoautotrophic, sulfur-oxidizing bacteria so far described. The names Thiomicrospira arctica sp. nov. and Thiomicrospira psychrophila sp. nov. are proposed for SVAL-E(T) (=ATCC 700955(T)=DSM 13458(T)) and SVAL-D(T) (=ATCC 700954(T)=DSM 13453(T)), respectively

Biology and culture of the clown loach Chromobotia macracanthus (Cypriniformes, Cobitidae) : 4- Thermal biology of embryos and larvae

The knowledge of how fish survive and grow at different temperatures, and how these traits vary between life stages, is essential to evaluate the effects of climate change on wild fish and implement effective strategies in aquaculture. These issues are addressed in this study through a series of experiments that evaluate the effect of temperature (23-34 degrees C) on the embryos and larvae of clown loach, Chromobotia macracanthus. This species is endemic to the rivers of Sumatra and Borneo, highly praised on the ornamental fish market, and has been reproduced in captivity recently. No embryo survived a 24-h exposure to 34 degrees C until the age of 3 days after hatching (dah); mortality was high at 32 degrees C at 2 and 3 dah, whereas it was low and similar from 1 to 4 dah at 23-29 degrees C (<10%). Yolk absorption was proportional to water temperature (Q(10 degrees C) of 1.69 in the 23-32 degrees C range), but fish reared at cold temperatures were larger than others at the start of exogenous feeding (5.7 vs. 5.5 mm TL, at 23 and 32 degrees C, respectively). The survival of larvae fed Artemia nauplii ad libitum was high at 23-32 degrees C (80-100%), but almost null at 34 degrees C. Growth models at different temperatures were produced from weekly measurements in two experiments, and tested by comparing their predictions with the results of a third experiment. Throughout the larval stage, the optimal temperature for growth (T. opt) was close to 29 degrees C, and departures from T. opt resulted in substantial growth penalties (-30% SGR for -5.1 degrees C and +3.1 degrees C). High survival, fast growth (0.7 mm day(-1)) and limited size dispersal at T. opt are encouraging perspectives for the aquaculture of clown loach. From an ecological perspective, the species has an atypical thermal biology, as it is less thermophilic than other tropical fishes, but more stenothermal than temperate fishes exhibiting similar values of T. opt, both traits being of particular concern in the context of global warming

Post-exercise Hot Water Immersion Elicits Heat Acclimation Adaptations in Endurance Trained and Recreationally Active Individuals

Hot water immersion (HWI) after exercise on 6 consecutive days in temperate conditions has been shown to provide heat acclimation adaptations in a recreationally active population. Endurance athletes experience frequent, sustained elevations in body temperature during training and competition; as a consequence, endurance athletes are considered to be partially heat acclimatized. It is therefore important to understand the extent to which endurance trained individuals may benefit from heat acclimation by post-exercise HWI. To this end, we compared the responses of eight endurance trained and eight recreationally active males (habitual weekly endurance exercise: 9 h vs. 3 h) to a 6-day intervention involving a daily treadmill run for 40 min (65% O2max) in temperate conditions followed immediately by HWI ( 0.05) for: the reduction in end-exercise rectal core temperature (T re, mean, endurance trained -0.36 degrees C; recreationally active -0.47 degrees C); the reduction in resting T re (endurance trained -0.17 degrees C; recreationally active -0.23 degrees C); the reduction in T re at sweating onset (endurance trained -0.22 degrees C; recreationally active -0.23 degrees C); and, the reduction in mean skin temperature (endurance trained -0.67 degrees C; recreationally active -0.75 degrees C: PRE to POST P < 0.01). Furthermore, training status did not significantly influence the observed reductions in mean O2, mean metabolic energy expenditure, end-exercise physiological strain index, perceived exertion or thermal sensation (PRE to POST P < 0.05). Only end-exercise heart rate was influenced by training status (P < 0.01, interaction); whereby, recreationally active but not endurance trained individuals experienced a significant reduction in end-exercise heart rate from PRE to POST (P < 0.01). In summary, these findings demonstrate that post-exercise HWI presents a practical strategy to reduce thermal strain during exercise-heat-stress in endurance trained and recreationally active individuals

Static and dynamic precipitation phenomena in laser powder bed-fused Ti6Al4V alloy

The present paper investigates static and dynamic precipitation phenomena in the Ti6Al4V alloy produced via laser-powder bed fusion, solubilized at 1050 degrees C and aged in the range of 450-650 degrees C. In relation to the distance from the platform on which the samples are disposed during the solution heat treatment, the microstructure varies from alpha-laths to alpha-colonies arranged in a Widmanstatten structure. The aging heat treatment at 450 degrees C promotes the formation of stacking faults into alpha-laths and the precipitation of alpha(2)-Ti3Al phases. SEM and TEM observations reveal that the density of precipitates increases after aging at 500 degrees C, while coarsening of the alpha-phase occurs only after aging heat treatment at 600 degrees C. Vickers microhardness measurements reveal different peak-aging conditions and show that the alloy is unstable at high temperatures (T &gt; 450 degrees C), both in the case of static and dynamic precipitation phenomena. Only the aging profile at 450 degrees C shows a constant trend of Vickers microhardness after 4 h of treatment

Lack of Metabolic Acclimation to Different Thermal Histories by Tadpoles of Limnodynastes Peroni (Anura: Leptodactylidae) 1

Tadpoles of Limnodynastes peroni show no evidence of any ability to undergo thermal metabolic acclimation when kept at 15 degrees C and 25 degrees C for periods up to 75 days. When kept for 90-120 days, small differences were seen between rate-temperature curves of 15 degrees C and 25 degrees C history tadpoles. The reality of these differences as evidence for thermal metabolic acclimation is difficult to assess. An overall equation to describe the effect of temperature (T, C) and weight (W, grams) on oxygen consumption (QO2, ml g-1 h-1) is log10 QO2 = -2.13 + 0.05T - 0.48 log10 W, for which r2 = 0.86 (no. = 360). Q10 is 3.16 and in the relationship M +/- Wb (where M = oxygen consumption, ml h-1), the exponent b = 0.52. The results suggest that in tadpoles of L. peroni any adaptations to fluctuating temperatures may be behavioral rather than physiological or biochemical

Optimization of deposition parameters for thin silicon films on flexible substrates in a hot-wire chemical vapor deposition reactor

This paper studies the deposition of thin silicon films from silane on plastic substrates in a recently build hot-wire chemical vapor deposition reactor. Hydrogen dilution of silane was used to induce amorphous-to-nanocrystalline phase transition. Thin-film deposition rate, r(d), is roughly proportional to silane concentration during deposition but the proportionality factor depends on filament temperature, T-fil. At T-fil similar to 2500 degrees C (1900 degrees C), r(d) increases from 2.1 angstrom/s (1.2 angstrom/s) at 97% H-2 dilution to 14.5 angstrom/s (10.7 angstrom/s) for films deposited from pure silane. At T-fil similar to 2500 degrees C, films deposited under 80% H-2 dilution were amorphous, under 90% H-2 dilution the crystalline fraction was X-C = 49.4% and under 95% H-2 dilution, X-C = 52.8%. At T-fil similar to 1900 degrees C, samples were amorphous up to similar to 95% H-2 dilution where a crystalline fraction of 22.3% was measured. Films with amorphous structure have sigma(d) similar to 10(-10)-10(-9) Omega(-1.)cm(-1) while those with a measured crystalline fraction have sigma(d)similar to 10(-7)-10(-5) Omega(-1)cm(-1), depending on the amount of crystalline fraction and grain size. Films with lower sigma(d) have optical band gap in the range similar to 1.85-1.9 eV, typical of hydrogenated amorphous silicon, while those with higher sigma(d) have larger optical band gap (similar to 2 eV), typical of hydrogenated nanocrystalline silicon. Adhesion of the films to the plastic substrate was good, as they survived bending to small radius of curvature (< 1 mm) without peeling. Structural, optical and transport properties were similar on films deposited both on PEN and on glass under the same deposition conditions.Fundação para a Ciência e a Tecnologia (FCT

Thiomicrospira kuenenii sp. nov., and Thiomicrospira frisia sp. nov., two mesophilic obligately chemolithoautotrophic sulfur-oxidizing bacteria isolated from an intertidal mud flat

Two new members of the genus Thiomicrospira were isolated from an intertidal mud flat sample with thiosulfate as the electron donor and CO2 as carbon source. On the basis of differences in genotypic and phenotypic characteristics, it is proposed that strain JB-A1(T) (= DSM 12350(T)) and strain JB-A2(T) (= DSM 12351(T)) are members of two new species, Thiomicrospira kuenenii and Thiomicrospira frisia, respectively. The cells were Gram-negative vibrios or slightly bent rods. Strain JB-A1(T) was highly motile, whereas strain JB-A2(T) showed a much lower degree of motility combined with a strong tendency to form aggregates. Both organisms were obligately autotrophic and strictly aerobic. Nitrate was not used as electron acceptor. Chemolithoautotrophic growth was observed with thiosulfate, tetrathionate, sulfur and sulfide. Neither isolate was able to grow heterotrophically. For strain JB-A1(T), growth was observed between pH values of 4.0 and 7.5 with an optimum at pH 6.0, whereas for strain JB-A2(T), growth was observed between pH 4.2 and 8.5 with an optimum at pH 6.5. The temperature limits for growth were between 3.5 and 42 degrees C and 3.5 and 39 degrees C, respectively. The optimum growth temperature for strain JB-A1(T) was between 29 and 33.5 degrees C, whereas strain JB-A2(T) showed optimal growth between 32 and 35 degrees C. The mean maximum growth rate on thiosulfate was 0.35 h(-1) for strain JB-A1(T) and 0.45 h(-1) for strain JB-A2(T)