The associated regulators and signal pathway in rIL-16／CD4 mediated growth regulation in Jurkat cells

IL-16 is a ligand and chemotactic factor for CD4 T cells. IL-16 inhibits the CD3 mediated lymphocyte activation and proliferation. The effects of IL-16 on the target cells are dependent on the cell type, the presence of co-activators etc. To understand the regulation function and mechanism of IL-16 on target cells, we used a 130 a.a. recombinant IL-16 to study its effects on the growth of Jurkat T leukemia cells in vitro. We found that the rIL-16 stimulated the proliferation of Jurkat cells at low dose (10^-9M), but inhibited the growth of the cells at higher concentration (10^-5M). Results showed that 10^-5 M of rIL-16 treatment induced an enhanced apoptosis in Jurkat cells. The treatment blocked the expression of FasL, but up-regulated the c-myc and Bid expression in the cells. Pre-treatment of PKC inhibitor or MEK1 inhibitor markedly increased or decreased the rIL-16 induced growth-inhibiting effects on Jurkat cells, respectively.The results suggested that the rIL-16 might be a regulator for the growth or apoptosis of Jurkat cells at a dose-dependent manner. The growth-inhibiting effects of rIL-16 might be Fas/FasL independent, but,associated with the activation of PKC, up-regulated expression of c-Myc and Bid, and the participation of the ERK signal pathway in Jurkat cells.     

Size mediated climate–growth relationships in Pinus halepensis and Pinus pinea

Functional processes in trees undergo changes as the tree size increases, which may affect the response of trees to environmental factors. We tested tree-ring response to climate in four groups of trees, including large and small Pinus halepensis and Pinus pinea trees using cluster, principal component (PC) and dendroclimatological analysis. The trees were of the same age and growing on a plantation in the semiarid coastal area of southern Spain. Cluster and PC analyses showed a clear separation into four groups of trees. Autocorrelation and mean sensitivity showed significant differences between the two size classes. PCA recognised four representative principal components where PC1 represented the tree-ring—climate variability common to both species and sizes, whereas PC2, PC3 and PC4 represented a species-specific and size-dependent response of trees to climate. The differences between the two size classes were greater than those between the two species. The results suggest that future tree-ring studies should include trees stratified by size. Only this would make it possible to produce unbiased predictions on the consequences of climate change and to devise suitable mitigation strategies for preserving Mediterranean forest ecosystems.     

Is auxin the repressor signal of branch growth in apical control?

"Apical control" is the repression of branch growth by a higher dominating branch or shoot. There has been some confusion in the literature concerning the meaning and causal mechanisms of this correlative phenomenon with those of "apical dominance," which term is often used in a strict sense to connote the repression of the initiation of axillary bud outgrowth by an active shoot apex. Although the term "apical control" is most commonly employed with respect to woody species, this phenomenon also widely occurs in herbaceous plants. Because of the strong evidence for a role of auxin as a repressor signal in apical dominance and partly because of this lack of distinction in terminology, a similar role for auxin in apical control is often assumed in spite of the obvious acropetal auxin transport difficulty and the lack of direct evidence for the acropetal transport of any inhibitor influence. In the present study with the herbaceous Ipomoea nil, it has been clearly demonstrated that while exogenous auxin (1% NAA) strongly restores apical dominance in the Thimann-Skoog experiment, auxin treatments to decapitated dominant shoots do not, in any observable way, restore apical control in lower dominated branches. Hence, in this fast-growing species, the hypothesis for the role of auxin as a repressor signal for apical control is not supported.     

β-Adrenoceptor mediated signal transduction in congestive heart failure in cardiomyopathic (UMX7.1) hamsters

In view of the lack of information regarding the status of -adrenoceptor mediated signal transduction mechanisms at severe stages of congestive heart failure, the status of -adrenoceptors, G-proteins and adenylyl cyclase activities was examined in 2202–275 day old cardiomyopathic hamster hearts. Although no changes in the Kd values for ₁- and ₂-adrenoceptors were seen, the number of ₁-adrenoceptors, unlike that of R2-adrenoceptors, was markedly decreased in cardiac membranes from failing hearts. The activation of adenylyl cyclase in the failing hearts by different concentrations of isoproterenol was also attenuated in comparison to the control preparations. The basal adenylyl cyclase activity in cardiac membranes from the failing hearts was not altered; however, the stimulated enzyme activities, when measured in the presence of forskolin, NaF or Gpp(NH)p were depressed significantly. The functional activity of Gs-proteins (measured by cholera toxin stimulation of adenylyl cyclase) was depressed whereas that of Gi-proteins (measured by pertussis toxin stimulation of adenylyl cyclase) was increased in the failing hearts. Not only were the Gs- and Gi-protein contents (measured by immunoblotting) increased, the bioactivities of these proteins as determined by ADP-ribosylations in the presence of cholera toxin and pertussis toxin, respectively, were also higher in failing hearts in comparison to the control values. Northern blot analysis revealed that the signals for Gs- and Gi-protein mRNAs were augmented at this stage of heart failure. These results indicate that the loss of adrenergic support at severe stages of congestive heart failure in cardiomyopathic hamsters may involve a reduction in the number of ₁-adrenoceptors, and an increase in Gi-protein contents as well as bioactivities in addition to an uncoupling of Gs-proteins from the catalytic site of adenylyl cyclase in cardiac membrane.     

How does a hypha grow? The biophysics of pressurized growth in fungi

The mechanisms underlying the growth of fungal hyphae are rooted in the physical property of cell pressure. Internal hydrostatic pressure (turgor) is one of the major forces driving the localized expansion at the hyphal tip which causes the characteristic filamentous shape of the hypha. Calcium gradients regulate tip growth, and secretory vesicles that contribute to this process are actively transported to the growing tip by molecular motors that move along cytoskeletal structures. Turgor is controlled by an osmotic mitogen-activated protein kinase cascade that causes de novo synthesis of osmolytes and uptake of ions from the external medium. However, as discussed in this Review, turgor and pressure have additional roles in hyphal growth, such as causing the mass flow of cytoplasm from the basal mycelial network towards the expanding hyphal tips at the colony edge.     

External tissue support and fluid–structure simulation in blood flows

The objective of this work is to address the formulation of an adequate model of the external tissue environment when studying a portion of the arterial tree with fluid–structure interaction. Whereas much work has already been accomplished concerning flow and pressure boundary conditions associated with truncations in the fluid domain, very few studies take into account the tissues surrounding the region of interest to derive adequate boundary conditions for the solid domain. In this paper, we propose to model the effect of external tissues by introducing viscoelastic support conditions along the artery wall, with two—possibly distributed—parameters that can be adjusted to mimic the response of various physiological tissues. In order to illustrate the versatility and effectiveness of our approach, we apply this strategy to perform patient-specific modeling of thoracic aortae based on clinical data, in two different cases and using a distinct fluid–structure interaction methodology for each, namely an Arbitrary Lagrangian–Eulerian (ALE) approach with prescribed inlet motion in the first case and the coupled momentum method in the second case. In both cases, the resulting simulations are quantitatively assessed by detailed comparisons with dynamic image sequences, and the model results are shown to be in very good adequacy with the data.     

The role of rock-phosphate-solubilizing fungi and vesicular–arbusular-mycorrhiza (VAM) in growth of wheat plants fertilized with rock phosphate

A total of 36 fungal species isolated from soil were tested for their ability to solubilize rock phosphate (RP) in agar plates. Most of these fungi were non-rock phosphate solubilizers, but two isolates, Aspergillus niger and Penicillium citrinum, had high activity. Liquid culture experiments revealed that both fungi caused a remarkable drop in pH of culture media and solubilized considerable amounts of phosphate. The effects on wheat of inoculation with vesicular–arbuscular mycorrhizal fungi and rock-phosphate-solubilizing fungi and fertilization with rock phosphate were studied in sterilized pot soils, nonsterilized pot trials and in field plot soils. Rock phosphate fertilization and inoculation with Glomus constrictum and rock-phosphate-solubilizing fungi (A. niger and P. citrinum) significantly increased dry matter yield of wheat plants under all experimental conditions. However, the effect was more evident in non- sterilized pot soils and in the field than in sterilized pots. Rock phosphate had no significant effect on the total phosphorus content of plants grown under pot conditions but it was significantly increased in field plots; the effect of inoculation with fungi (G. constrictum, A. niger and P. citrinum) on plant phosphorus was closely related to this in dry matter production. The greatest positive effect on growth and phosphorus contents of wheat plants was recorded in the treatments that received rock phosphate and were inoculated with a mixed inoculum of the three microorganisms used, followed by dual inoculation treatments of G. constrictum plus either A. niger or P. citrinum.     

The role of rock-phosphate-solubilizing fungi and vesicular–arbusular-mycorrhiza (VAM) in growth of wheat plants fertilized with rock phosphate

A total of 36 fungal species isolated from soil were tested for their ability to solubilize rock phosphate (RP) in agar plates. Most of these fungi were non-rock phosphate solubilizers, but two isolates, Aspergillus niger and Penicillium citrinum, had high activity. Liquid culture experiments revealed that both fungi caused a remarkable drop in pH of culture media and solubilized considerable amounts of phosphate. The effects on wheat of inoculation with vesicular–arbuscular mycorrhizal fungi and rock-phosphate-solubilizing fungi and fertilization with rock phosphate were studied in sterilized pot soils, nonsterilized pot trials and in field plot soils. Rock phosphate fertilization and inoculation with Glomus constrictum and rock-phosphate-solubilizing fungi (A. niger and P. citrinum) significantly increased dry matter yield of wheat plants under all experimental conditions. However, the effect was more evident in non- sterilized pot soils and in the field than in sterilized pots. Rock phosphate had no significant effect on the total phosphorus content of plants grown under pot conditions but it was significantly increased in field plots; the effect of inoculation with fungi (G. constrictum, A. niger and P. citrinum) on plant phosphorus was closely related to this in dry matter production. The greatest positive effect on growth and phosphorus contents of wheat plants was recorded in the treatments that received rock phosphate and were inoculated with a mixed inoculum of the three microorganisms used, followed by dual inoculation treatments of G. constrictum plus either A. niger or P. citrinum.     

Ergosterol — A measure of fungal growth in wood for staining and pitch control fungi

Summary A modified ergosterol analysis method, including a simultaneous saponification and refluxing extraction procedure along with HPLC quantification, was used to measure fungal colonization rate in wood. In liquid media the ergosterol content of the mycelia was measured and correlated to the fungal dry weight. In work on investigating staining fungal proteinase production on wood, ergosterol values were used to monitor fungal growth and to determine when maximum proteinase activity occurred. Similarly, we correlated ergosterol values with the decrease of wood lipids during pitch control fungal colonization.     

γ-Aminobutyric acid (GABA) homeostasis regulates pollen germination and polarized growth in Picea wilsonii

γ-Aminobutyric acid (GABA) is a four-carbon non-protein amino acid found in a wide range of organisms. Recently, GABA accumulation has been shown to play a role in the stress response and cell growth in angiosperms. However, the effect of GABA deficiency on pollen tube development remains unclear. Here, we demonstrated that specific concentrations of exogenous GABA stimulated pollen tube growth in Picea wilsonii, while an overdose suppressed pollen tube elongation. The germination percentage of pollen grains and morphological variations in pollen tubes responded in a dose-dependent manner to treatment with 3-mercaptopropionic acid (3-MP), a glutamate decarboxylase inhibitor, while the inhibitory effects could be recovered in calcium-containing medium supplemented with GABA. Using immunofluorescence labeling, we found that the actin cables were disorganized in 3-MP treated cells, followed by the transition of endo/exocytosis activating sites from the apex to the whole tube shank. In addition, variations in the deposition of cell wall components were detected upon labeling with JIM5, JIM7, and aniline blue. Our results demonstrated that calcium-dependent GABA signaling regulates pollen germination and polarized tube growth in P. wilsonii by affecting actin filament patterns, vesicle trafficking, and the configuration and distribution of cell wall components.     

Bcl-2 blocks apoptotic signal of transforming growth factor-β in human hepatoma cells

Transforming growth factor- (TGF-) has been shown to induce apoptosis on normal hepatocytes and hepatoma cells both in vitro and in vivo. However, how the TGF- induces apoptosis is still not clear. We examined the expression of anti-apoptosis proteins and sensitivity to TGF- in three well differentiated human hepatoma cell lines. Two TGF- sensitive cell lines Hep3B and HuH7 totally lacked Bcl-2. In contrast, the TGF- resistant HepG2 cells expressed a substantial amount of Bcl-2. All three cell lines expressed equal amounts of Bcl-X_L, Bcl-X_S and Bax. Overexpression of Bcl-2 in Hep3B and HuH7 cells protected them from TGF--induced apoptosis. TGF- treatment increased intracellular peroxide production and suppressed the expression of glutathione-S-transferase in the Hep3B cells, and these effects were partially suppressed by the overexpression of Bcl-2. These results suggest that Bcl-2 may protect cell from TGF--F-induced apoptosis by interfering TGF- generated signals leading to induce reactive oxygen species production.     

Degradation and corrosive activities of fungi in a diesel–mild steel–aqueous system

The fungi Aspergillus fumigatus, Hormoconis resinae and Candida silvicola were isolated from the fuel/water interfacial biomass in diesel storage tanks in Brazil. Their corrosive activities on mild steel ASTM A 283-93-C, used in storage tanks for urban diesel, were evaluated after various times of incubation at 30 °C in a modified Bushnell–Haas mineral medium (without chlorides) with diesel oil as sole source of carbon. Their ability to degrade diesel oil was evaluated after growth for 30 and 60 days. The fungus Aspergillus fumigatus and the consortium of all three organisms showed the highest production of biomass; A. fumigatus gave the greatest value for steel weight loss and produced the greatest reduction in pH of the aqueous phase. Solid phase microextraction (SPME) showed that the main acid present in the aqueous phase after 60 days incubation with A. fumigatus was propionic acid. Polarization curves indicated that microbial activity influenced the anodic process, probably by the production of corrosive metabolites, and that this was particularly important in the case of A. fumigatus. This fungus preferentially degraded aliphatic hydrocarbons of chain lengths C₁₁--C₁₃ in the diesel, producing 47.7, 37.5 and 51% reductions in C₁₁, C₁₂ and C₁₃, respectively. It produced more degradation than the consortium after 60 days incubation. It is likely that the presence of other species in the consortium inhibited the growth of A. fumigatus, thus resulting in a lower rate of diesel fuel degradation.