3,675 research outputs found
Developmental Acquisition of Regulomes Underlies Innate Lymphoid Cell Functionality
Innate lymphoid cells (ILCs) play key roles in host defense, barrier integrity, and homeostasis and mirror adaptive CD4(+) T helper (Th) cell subtypes in both usage of effector molecules and transcription factors. To better understand the relationship between ILC subsets and their Th cell counterparts, we measured genome-wide chromatin accessibility. We find that chromatin in proximity to effector genes is selectively accessible in ILCs prior to high-level transcription upon activation. Accessibility of these regions is acquired in a stepwise manner during development and changes little after in vitro or in vivo activation. Conversely, dramatic chromatin remodeling occurs in naive CD4(+) T cells during Th cell differentiation using a type-2-infection model. This alteration results in a substantial convergence of Th2 cells toward ILC2 regulomes. Our data indicate extensive sharing of regulatory circuitry across the innate and adaptive compartments of the immune system, in spite of their divergent developing pathways
The potency of the broad spectrum bacteriocin, bactofencin A, against staphylococci is highly dependent on primary structure, N-terminal charge and disulphide formation
Bactofencin A is a novel class IId bacteriocin, produced by the intestinal isolate Lactobacillus salivarius DPC6502, which has potent activity against medically significant pathogens including Staphylococcus aureus. This bacteriocin is unusual in that it has a highly cationic N terminus and a single disulfide bond between Cys7 and Cys22, resulting in a large C terminal loop. In this study, a library of synthetic bactofencin A variants were screened against the mastitis isolate, S. aureus DPC5246, to identify key residues responsible for activity. It was apparent that substituting either cysteine of the disulfide bond with either serine or alanine significantly reduced the activity of the bacteriocin, confirming the importance of the C terminal loop. Substituting N terminal amino acids with alanine had no effect on activity, whereas sequential removal of the N terminal positively charged residues resulted in an increasingly inactive peptide. A complete (synthetic) alanine scanning analysis revealed that the residues between Val9 and Gly17 were most affected by substitution suggesting that this area has a major influence on the potency of the bacteriocin. Substituting residues in the loop region between Cys7 and Cys22 for D-amino acid equivalents had a more detrimental effect on activity than L-alanine substitutions. Specifically Y10A, N11A, P15A and T16A are active at 4, 16, 1 and 16 μM respectively while their D equivalents were inactive at 1000 μM, the highest concentration tested. Ultimately, this study identifies the critical features in the primary structure of the bacteriocin which gives it such potent activity against pathogenic staphylococci
The application of a Trous wave filtering and Monte Carlo analysis on SECIS 2001 solar eclipse observations
8000 images of the Solar corona were captured during the June 2001 total
Solar eclipse. New software for the alignment of the images and an automated
technique for detecting intensity oscillations using multi scale wavelet
analysis were developed. Large areas of the images covered by the Moon and the
upper corona were scanned for oscillations and the statistical properties of
the atmospheric effects were determined. The a Trous wavelet transform was used
for noise reduction and Monte Carlo analysis as a significance test of the
detections. The effectiveness of those techniques is discussed in detail.Comment: 17 pages, 8 figures, accepted by Solar Physics Journal for
publication in Topical Issue: "Frontiers in Solar Image Processing
Ants show a leftward turning bias when exploring unknown nest sites
Behavioural lateralization in invertebrates is an important field of study because it may provide insights into the early origins of lateralization seen in a diversity of organisms. Here, we present evidence for a leftward turning bias in Temnothorax albipennis ants exploring nest cavities and in branching mazes, where the bias is initially obscured by thigmotaxis (wall-following) behaviour. Forward travel with a consistent turning bias in either direction is an effective nest exploration method, and a simple decision-making heuristic to employ when faced with multiple directional choices. Replication of the same bias at the colony level would also reduce individual predation risk through aggregation effects, and may lead to a faster attainment of a quorum threshold for nest migration. We suggest the turning bias may be the result of an evolutionary interplay between vision, exploration and migration factors, promoted by the ants' eusociality
Quantum Fluctuations Driven Orientational Disordering: A Finite-Size Scaling Study
The orientational ordering transition is investigated in the quantum
generalization of the anisotropic-planar-rotor model in the low temperature
regime. The phase diagram of the model is first analyzed within the mean-field
approximation. This predicts at a phase transition from the ordered to
the disordered state when the strength of quantum fluctuations, characterized
by the rotational constant , exceeds a critical value . As a function of temperature, mean-field theory predicts a range of
values of where the system develops long-range order upon cooling, but
enters again into a disordered state at sufficiently low temperatures
(reentrance). The model is further studied by means of path integral Monte
Carlo simulations in combination with finite-size scaling techniques,
concentrating on the region of parameter space where reentrance is predicted to
occur. The phase diagram determined from the simulations does not seem to
exhibit reentrant behavior; at intermediate temperatures a pronounced increase
of short-range order is observed rather than a genuine long-range order.Comment: 27 pages, 8 figures, RevTe
First star formation with dark matter annihilation
We include an energy term based on Dark Matter (DM) self-annihilation during
the cooling and subsequent collapse of the metal-free gas, in halos hosting the
formation of the first stars in the Universe. We have found that the feedback
induced on the chemistry of the cloud does modify the properties of the gas
throughout the collapse. However, the modifications are not dramatic, and the
typical Jeans mass within the halo is conserved throughout the collapse, for
all the DM parameters we have considered. This result implies that the presence
of Dark Matter annihilations does not substantially modify the Initial Mass
Function of the First Stars, with respect to the standard case in which such
additional energy term is not taken into account. We have also found that when
the rate of energy produced by the DM annihilations and absorbed by the gas
equals the chemical cooling (at densities yet far from the actual formation of
a proto-stellar core) the structure does not halt its collapse, although that
proceeds more slowly by a factor smaller than few per cent of the total
collapse time.Comment: 12 pages, 8 figures, 3 tables; replaced with published version after
minor change
MicroRNA-221 and -222 modulate intestinal inflammatory Th17 cell response as negative feedback regulators downstream of interleukin-23
Mikami et al. examine the role of miR-221/222 in helper T cells in the gut. MiR-221/222 are induced by IL-23 and suppressed by TGFβ, targeting Maf and IL23r for degradation. During inflammation, these miRNAs serve as a negative feedback rheostat to constrain IL23-Th17 cell responses
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