O-GlcNAcylation: key regulator of glycolytic pathways

Elevated O-GlcNAcylation is emerging as a general characteristic of most cancers. Although O-GlcNAcylation can regulate many cell biological pathways, recent evidence suggests that it is a key regulator of metabolic pathways including glycolysis in cancer cells. This review summarizes our current understanding of how O-GlcNAcylation regulates glycolytic pathways and contributes to alterations in cancer cell metabolism.     

Using variation partitioning techniques to quantify the effects of invasive alien species on native urban bird assemblages

Quantifying the impacts that invasive alien species (IAS) cause on affected systems is not an easy task. Here, we explore the application of variation partitioning techniques to measure and control for the effects of possible confounding factors when studying the impact that feral pigeons, European starlings, and house sparrows cause on native urban bird communities in Mexico. We argue that these IAS are provoking a severe impact on whole assemblages of native passerines only if (a) their marginal effect is statistically significant, (b) it remains so after partialling out other explanatory variables, and (c) is larger than (or similar to) the conditional effect of these covariates. We censused passerine bird assemblages and measured habitat variables in a number of greenspaces in three replicate study areas. Then, by means of partial redundancy analyses, we decomposed the total variability in bird data as a function of IAS, physical variables and vegetation data. In one of the study areas the marginal effect of IAS on native assemblages was significant, but the conditional effect was not. We conclude that this IAS effect was confounded with other explanatory variables. In the other study areas, no (marginal or partial) significant effect was found. Without invoking interspecific competition, our results support the opportunistic hypothesis, according to which IAS can exploit ecological conditions in modern cities that native species cannot even tolerate. Finally, apart from the Precautionary Principle, we found no scientific justification to control the abundance of the three IAS in our study areas.     

How reliable are the Powell–Wetherall plot method and the maximum-length approach? Implications for length-based studies of growth and mortality

Length-based methods are the cornerstone of many population studies and stock assessments. This study tested two widely used methods: the Powell–Wetherall (P–W) plot and the L_max approach (i.e., estimating L_∞ directly from L_max). In most simulations, P–W estimates of the ratio total mortality/growth (Z/K ratio) were biased beyond acceptable limits (bias?>?30%). Bias in Z/K showed a complex behavior, without possible corrections. Estimates of asymptotic length (L_∞) were less biased than Z/K, but were very sensitive to intra-cohort variability in growth and to changes in the occurrence of large individuals in the sample. Exclusion of the largest size classes during the regression procedure or weighing by abundance does not solve these issues. Perfect linearization of the data and extremely narrow confidence intervals for Z/K will lead users to erroneous overconfidence in outputs. Clearly, the P–W method is not suitable for the assessment of Z/K ratios of natural populations. Estimation of L_∞ may be tentatively possible under very specific conditions, with necessary external verifications. Also, this study demonstrates that there is no way to estimate L_∞ directly from L_max, since there is no particular relationship to expect a priori between L_∞ and L_max. Errors in estimating L_∞ directly affect the estimate of the growth constant K and all other subsequent calculations in population studies, stock assessments and ecosystem models. New approaches are urgently needed for length-based studies of body growth (e.g., unconstrained curve fit with subsequent bootstrapping), that consider the inherent uncertainty regarding the underlying data and processes.     

Phylogenetic diversity is a better predictor of wetland community resistance to Alternanthera philoxeroides invasion than species richness

• Highly biodiversity communities have been shown to better resist plant invasions through complementarity effects. Species richness (SR) is a widely used biodiversity metric but lacks explanatory power when there are only a few species. Communities with low SR can have a wide variety of phylogenetic diversities (PD), which might allow for a better prediction of invasibility.
• We assessed the effect of diversity reduction of a wetland community assemblage typical of the Beijing area on biotic resistance to invasion of the exotic weed Alternanthera philoxeroides and compared the reduction in SR and PD in predicting community invasibility.
• The eight studied resident species performed similarly when grown alone and when grown in eight‐species communities together with the invasive A. philoxeroides. Variation partitioning showed that PD contributed more to variation in both A. philoxeroides traits and community indicators than SR. All A. philoxeroides traits and community indicators, except for evenness index, showed a linear relationship with PD. However, only stem length of A. philoxeroides differed between the one‐ and two‐species treatments, and the diversity index of the communities differed between the one‐ and two‐species treatments and between the one‐ and four‐species treatments.
• Our results showed that in natural or semi‐natural wetlands with relatively low SR, PD may be a better predictor of invasibility than SR. When designing management strategies for mitigating A. philoxeroides invasion, deliberately raising PD is expected to be more efficient than simply increasing species number.

     

High-speed broadband monitoring of cell viscoelasticity in real time shows myosin-dependent oscillations

Study of the dynamic evolutions of cell viscoelasticity is important as during cell activities such as cell metastasis and invasion, the rheological behaviors of the cells also change dynamically, reflecting the biophysical and biochemical connections between the outer cortex and the intracellular structures. Although the time variations of the static modulus of cells have been investigated, few studies have been reported on the dynamic variations of the frequency-dependent viscoelasticity of cells. Measuring and monitoring such dynamic evolutions of cells at nanoscale can be challenging as the measurement needs to meet two objectives inherently contradictory to each other—the measurement must be broadband (to cover a large frequency spectrum) but also rapid (to capture the time-elapsed changes). In this study, we exploited a recently developed control-based nanomechanical protocol of atomic force microscope to monitor in real time the dynamic evolutions of the viscoelasticity of live human prostate cancer cells (PC-3 cells) and study its dependence on myosin activities. We found that the viscoelasticity of PC-3 cells, followed the power law, and oscillated at a period of about 200 s. Both the amplitude and the frequency of the oscillation strongly depended on the intracellular calcium and blebbistatin-sensitive motor proteins.     

Notch pathway plays a novel and critical role in regulating responses of T and antigen-presenting cells in aGVHD

Graft-versus-host disease (GVHD) induced by host antigen-presenting cells (APCs) and donor-derived T cells remains the major limitation of allogeneic bone marrow transplantation (allo-BMT). Notch signaling pathway is a highly conserved cell-cell communication that is important in T cell development. Recently, Notch signaling pathway is reported to be involved in regulating GVHD. To investigate the role of Notch inhibition in modulating GVHD, we established MHC-mismatched murine allo-BMT model. We found that inhibition of Notch signaling pathway by γ-secretase inhibitor in vivo could reduce aGVHD, which was shown by the onset time of aGVHD, body weight, clinical aGVHD scores, pathology aGVHD scores, and survival. Inhibition of Notch signaling pathway by DAPT ex vivo only reduced pathology aGVHD scores in the liver and intestine and had no impact on the onset time and clinical aGVHD scores. We investigated the possible mechanism by analyzing the phenotype of host APCs and donor-derived T cells. Notch signaling pathway had a broad effect on both host APCs and donor-derived T cells. The expressions of CD11c, CD40, and CD86 as the markers of activated dendritic cells (DCs) were decreased. The proliferative response of CD8+ T cell decreased, while CD4⁺ Notch-deprived T cells had preserved expansion with increased expressions of CD25 and Foxp3 as markers of regulatory T cells (Tregs). In conclusion, Notch inhibition may minimize aGVHD by decreasing proliferation and activation of DCs and CD8⁺ T cells while preserving Tregs expansion.     

Site,trigger, quenching mechanism and recovery of non-photochemical quenching in cyanobacteria: recent updates

Femtosecond transient absorption was used to study excitation decay in monomeric and trimeric cyanobacterial Photosystem I (PSI) being prepared in three states: (1) in aqueous solution, (2) deposited and dried on glass surface (either conducting or non-conducting), and (3) deposited on glass (conducting) surface but being in contact with aqueous solvent. The main goal of this contribution was to determine the reason of the acceleration of the excitation decay in dried PSI deposited on the conducting surface relative to PSI in solution observed previously using time-resolved fluorescence (Szewczyk et al., Photysnth Res 132(2):111–126, 2017). We formulated two alternative working hypotheses: (1) the acceleration results from electron injection from PSI to the conducting surface; (2) the acceleration is caused by dehydration and/or crowding of PSI proteins deposited on the glass substrate. Excitation dynamics of PSI in all three types of samples can be described by three main components of subpicosecond, 3–5, and 20–26 ps lifetimes of different relative contributions in solution than in PSI-substrate systems. The presence of similar kinetic components for all the samples indicates intactness of PSI proteins after their deposition onto the substrates. The kinetic traces for all systems with PSI deposited on substrates are almost identical and they decay significantly faster than the kinetic traces of PSI in solution. We conclude that the accelerated excitation decay in PSI-substrate systems is caused mostly by dense packing of proteins.     

Trainmasters or Easyjet pilots? Historical production,labor organizing,and the Spanish engine drivers’ union

This article presents an analysis of the relationship between historical memory and the emergence and reproduction of a specific model of unionism. I argue that in order to understand the militant particularism of the Spanish engine drivers, we need to look at the historical representations that it is embedded in. Recourse to a generational framework makes possible the sustained presentation of the union as a case of successful workers’ organizing, in spite of evidence to the contrary. The historical ethnographic analysis of SEMAF, the Spanish engine drivers’ union, contributes to the analysis of historical memory within the contemporary anthropology of class. The article contributes to theoretical debates in the anthropology of class by reclaiming Michel Trouillot’s conceptualization of the historical process. Two aspects of Trouillot’s work are singled out: his dynamic understanding of the process of historical production and the corollary formulation of the overlapping capacities in which people participate in it (as agents, actors, and subjects) and his emphasis on the importance of expanding scholarly views of the field of historical production.