Dialect use in large assemblies: a study in European starling Sturnus vulgaris roosts

Dialects may signal social or population identity and increase tolerance within communities. We hypothesized that in European starling Sturnus vulgaris communal roosts, birds coming from the same breeding area, i.e. dialectal zone, might tend to stay together within the roost. Recordings were performed in the colonies, revealed in earlier studies, multiple dialects and small sectors where birds shared the same variants at the different levels. We also performed recordings in different locations within night roosts. The dialects recorded in the roosts were the same as those recorded at nest sites during the day and they were not distributed randomly within roosts: birds from the same geographical diurnal origin would gather and stay together, either because they arrived together or were attracted to their dialect. Although our results have to be confirmed by the study of identifiable individuals, we propose original lines of thought on roost structuring and on the role of song dialects.     

Chronic interleukin-6 (IL-6) treatment increased IL-6 secretion and induced insulin resistance in adipocyte: prevention by rosiglitazone

IL-6 has emerged as an important cytokine upregulated in states of insulin resistance such as type 2 diabetes. We evaluated the chronic effect of IL-6 on insulin signaling in 3T3-F442A and 3T3-L1 adipocytes. First, cells responded to a chronic treatment with IL-6 by initiating an autoactivation process that increased IL-6 secretion. Second, IL-6-treated adipocytes showed a decreased protein expression of IR-beta subunit and IRS-1 but also an inhibition of the insulin-induced activation of IR-beta, Akt/PKB, and ERK1/2. Moreover, IL-6 suppressed the insulin-induced lipogenesis and glucose transport consistent with a diminished expression of GLUT4. IL-6-treated adipocytes failed to maintain their adipocyte phenotype as shown by the downregulation of the adipogenic markers FAS, GAPDH, aP2, PPAR-gamma, and C/EBP-alpha. IL-6 also induced the expression of SOCS-3, a potential inhibitor of insulin signaling. Finally, the effects of IL-6 could be prevented by rosiglitazone, an insulin-sensitizing agent. Thus, IL-6 may play an important role in the set-up of insulin resistance in adipose cell.     

Nutrient limitation in rainforests and cloud forests along a 3,000-m elevation gradient in the Peruvian Andes

We report results from a large-scale nutrient fertilization experiment along a “megadiverse” (154 unique species were included in the study) 3,000-m elevation transect in the Peruvian Andes and adjacent lowland Amazonia. Our objectives were to test if nitrogen (N) and phosphorus (P) limitation shift along this elevation gradient, and to determine how an alleviation of nutrient limitation would manifest in ecosystem changes. Tree height decreased with increasing elevation, but leaf area index (LAI) and diameter at breast height (DBH) did not vary with elevation. Leaf N:P decreased with increasing elevation (from 24 at 200 m to 11 at 3,000 m), suggesting increased N limitation and decreased P limitation with increasing elevation. After 4 years of fertilization (N, P, N + P), plots at the lowland site (200 m) fertilized with N + P showed greater relative growth rates in DBH than did the control plots; no significant differences were evident at the 1,000 m site, and plots fertilized with N at the highest elevation sites (1,500, 3,000 m) showed greater relative growth rates in DBH than did the control plots, again suggesting increased N constraint with elevation. Across elevations in general N fertilization led to an increase in microbial respiration, while P and N + P addition led to an increase in root respiration and corresponding decrease in hyphal respiration. There was no significant canopy response (LAI, leaf nutrients) to fertilization, suggesting that photosynthetic capacity was not N or P limited in these ecosystems. In sum, our study significantly advances ecological understanding of nutrient cycling and ecosystem response in a region where our collective knowledge and data are sparse: we demonstrate N limitation in high elevation tropical montane forests, N and P co-limitation in lowland Amazonia, and a nutrient limitation response manifested not in canopy changes, but rather in stem and belowground changes.     

Sampling estuarine fish using multi-mesh gill nets: Effects of panel length and soak and setting times

Experiments on the effects of soak (1, 3 and 6 h) and setting times (18:00, 22:00 and 3:00 h), and panel length (20, 50, 120 m) on catches of fish in multi-mesh (38, 54 and 89 mm) gill nets were done in a south-east Australian estuary to develop an optimal, representative and standardized sampling methodology for future fishery-independent surveys of estuarine icthyofauna. Univariate analysis revealed that while the longest soak times and panels often caught significantly more numbers and species of fish, there were no differences between short and intermediate soak times. Further, where differences between soak time and panel length treatments were detected, fish were often being caught in the same relative proportions. Standardized catch-per-unit-of-effort (CPUE) (numbers of fish caught 20 m^− 1 of net h^− 1) decreased significantly with increasing soak time, but there were no differences in CPUE between different panel lengths for the total numbers of fish and key species caught. Multivariate analyses failed to detect any differences in fish assemblages between soak times and panel lengths for 38 and 89 mm mesh. However, inconsistent and species-specific differences in the abundances of common species accounted for differences in assemblage structure for the 54 mm mesh. Similarly, while the size ranges of most species of economic importance were comparable between different panel lengths and soak times, there were inconsistent differences in the proportions of fish captured across size classes for some species. Setting time had no effect on the mean numbers of fish or species caught, structure of assemblages or size-ranges of most species investigated. Based on these results, the use of 20-m panels soaked for 1 h at any time during the night was considered optimal for future surveys. The benefits of this uniform sampling methodology are discussed in terms of increased replication, reduced costs and the potential for lower fish mortality.     

SC5 mAb represents a unique tool for the detection of extracellular vimentin as a specific marker of Sezary cells

Circulating malignant Sézary lymphocytes result from a clonal proliferation of memory/activated CD4(+)CD45RO(+) T lymphocytes primarily involving the skin. Recently, the CD158k/KIR3DL2 cell surface receptor has been identified to phenotypically characterize these cells. We previously described a mAb termed SC5 that identifies an unknown early activation cell membrane molecule. It is expressed selectively by T lymphocytes isolated from healthy individuals upon activation, and by circulating Sézary syndrome lymphocytes. In addition, we found that SC5 mAb was reactive with all resting T lymphocytes once permeabilized, indicating that SC5 mAb-reactive molecule might present distinct cellular localization according to the T cell activation status. In this study, we show for the first time that SC5 mAb recognizes the intermediate filament protein vimentin when exported to the extracellular side of the plasma membrane of viable Sézary malignant cells. We demonstrate that SC5 mAb is unique as it reacts with both viable malignant lymphocytes and apoptotic T cells. As vimentin is also detected rapidly at the cell membrane surface after normal T lymphocyte activation, it suggests that its extracellular detection on Sézary cells could be a consequence of their constitutive activation status. Finally, as a probable outcome of vimentin cell surface expression, autoantibodies against vimentin were found in the sera of Sézary syndrome patients.     

Arabidopsis thaliana expresses multiple lines of defense to counterattack Erwinia chrysanthemi

Many taxonomically diverse plant species are attacked by Erwinia chrysanthemi, a member of the causal agents of soft-rotting diseases. Symptom development is due to the collective action of pectin-degrading enzymes secreted by the bacterium through a type II secretion system (T2SS). Using Arabidopsis thaliana as a susceptible host, we show that plants respond to E. chrysanthemi 3937 by expressing cell-wall reactions, production of an oxidative burst, and activation of salicylic acid (SA) and jasmonic acid (JA) or ethylene (ET) signaling pathways. We found that the oxidative burst is mainly generated via the expression of the AtrbohD gene, constitutes a barrier of resistance to bacterial attack, and acts independently of the SA-mediated response. To determine the importance of T2SS-secreted proteins in elicitation of these defenses, we used a T2SS deficient mutant and purified enzymatic preparations of representative members of strain 3937 pectate lyase activity. The T2SS-secreted proteins were responsible only partially for the activation of SA and JA or ET signaling pathways observed after infection with the wild-type bacterium and were not involved in the expression of other identified defense reactions. Our study shows the differential role played by pectate lyases isoenzymes in this process and highlights the complexity of the host immune network, which is finely controlled by the bacterium.     

Galig, a novel cell death gene that encodes a mitochondrial protein promoting cytochrome c release

Galectin-3 internal gene (Galig) was recently identified as an internal gene transcribed from the second intron of the human galectin-3 gene that is implicated in cell growth, cell differentiation, and cancer development. In this study, we show that galig expression causes morphological alterations in human cells, such as cell shrinkage, cytoplasm vacuolization, nuclei condensation, and ultimately cell death. These alterations were associated with extramitochondrial release of cytochrome c, a known cell death effector. Furthermore, Bcl-xL co-transfection significantly reduced the release of cytochrome c induced by galig expression, suggesting a common pathway between the cytotoxic activity of galig and the anti-apoptotic activity of Bcl-xL. This antagonism was not observed upon co-transfection of Bcl-2 and galig. Galig encodes a mitochondrial-targeted protein named mitogaligin. Structure-activity relationship studies showed that the mitochondrial addressing of mitogaligin relies on an internal sequence that is required and sufficient for the release of cytochrome c and cell death upon cell transfection. Moreover, incubation of isolated mitochondria with peptides derived from mitogaligin induces cytochrome c release. Altogether, these results show that galig is a novel cell death gene encoding mitogaligin, a protein promoting cytochrome c release upon direct interaction with the mitochondria.     

Identification of the cytoplasmic domains of CXCR4 involved in Jak2 and STAT3 phosphorylation

The chemokine SDF-1alpha transduces G(i)-dependent and -independent signals through CXCR4. Activation of Jak2/STAT3, a G(i)-independent signaling pathway, which plays a major role in survival signals, is known to be activated after SDF-1alpha binding to CXCR4 but the domains of CXCR4 involved in this signaling remain unexplored. Using human embryonic kidney HEK-293 cells stably expressing wild-type or mutated forms of CXCR4, we demonstrated that STAT3 phosphorylation requires the N-terminal part of the third intracellular loop (ICL3) and the tyrosine 157 present at the end of the second intracellular loop (ICL2) of CXCR4. In contrast, neither the conserved Tyr(135) in the DRY motif at the N terminus of ICL2 nor the Tyr(65) and Tyr(76) in the first intracellular loop (ICL1) are involved in this activation. ICL3, which does not contain any tyrosine residues, is needed to activate Jak2. These results demonstrate that two separate domains of CXCR4 are involved in Jak2/STAT3 signaling. The N-terminal part of ICL3 is needed to activate Jak2 after SDF-1alpha binding to CXCR4, leading to phosphorylation of only one cytoplasmic Tyr, present at the C terminus of ICL2, which triggers STAT3 activation. This work has profound implications for the understanding of CXCR4-transduced signaling.     

Piggy-BACing the human genome II. A high-resolution, physically anchored, comparative map of the porcine autosomes

Using the INRA-Minnesota porcine radiation hybrid panel, we have constructed a human-pig comparative map composed of 2274 loci, including 206 ESTs and 2068 BAC-end sequences, assigned to 34 linkage groups. The average spacing between comparative anchor loci is 1.15 Mb based on human genome sequence coordinates. A total of 51 conserved synteny groups that include 173 conserved segments were identified. This radiation hybrid map has the highest resolution of any porcine map to date and its integration with the porcine linkage map (reported here) will greatly facilitate the positional cloning of genes influencing complex traits of both agricultural and biomedical interest. Additionally, this map will provide a framework for anchoring contigs generated through BAC fingerprinting efforts and assist in the selection of a BAC minimal tiling path and assembly of the first sequence-ready map of the porcine genome.