Triangles in the graph of conjugacy classes of normal subgroups

[EN] Let G be a finite group and N a normal subgroup of G. We determine the structure of N when the graph G(N), which is the graph associated to the conjugacy classes of G contained in N, has no triangles and when the graph consists in exactly one triangle.The research of the first and second authors is supported by the Valencian Government, Proyecto PROMETEOII/2015/011. The first and the third authors are also partially supported by Universitat Jaume I, Grant P11B2015-77.Beltrán, A.; Felipe Román, MJ.; Melchor, C. (2017). Triangles in the graph of conjugacy classes of normal subgroups. Monatshefte für Mathematik. 182(1):5-21. https://doi.org/10.1007/S00605-015-0866-9S5211821Bertram, E.A., Herzog, M., Mann, A.: On a graph related to conjugacy classes of groups. Bull. London Math. Soc. 22(6), 569-575 (1990)Beltrán, A., Felipe, M.J., Melchor, C.: Graphs associated to conjugacy classes of normal subgroups in finite groups. J. Algebra 443, 335-348 (2015)Camina, A.R.: Arithmetical conditions on the conjugacy class numbers of a finite group. J. London Math. Soc. 2(5), 127-132 (1972)Deaconescu, M.: Classification of finite groups with all elements of prime order. Proc. Am. Math. Soc. 106(3), 625-629 (1989)Doerk, K., Hawkes, T.: Finite soluble groups. de Gruyter Expositions in Mathematics, vol. 4. Walter de Gruyter, Berlin (1992)Fang, M., Zhang, P.: Finite groups with graphs containing no triangles. J. Algebra 264(2), 613-619 (2003)Higman, G.: Finite groups in which every element has prime power order. J. London Math. Soc. 32, 335-342 (1957)Manz, O., Wolf, T.R.: Representations of solvable groups. Cambridge Univ. Press, Cambridge (1993)Riese, U., Shahabi, M.A.: Subgroups which are the union of four conjugacy classes. Commun. Algebra 29(2), 695-701 (2001)Shahryari, M., Shahabi, M.A.: Subgroups which are the union of three conjugate classes. J. Algebra 207(1), 326-332 (1998)The GAP Group.: GAP–groups, algorithms and programming, Vers. 4.4.12. (2008). http://www.gap-system.or

Inactivation of CREBBP expands the germinal center B cell compartment, down-regulates MHCII expression and promotes DLBCL growth

The genes encoding the histone acetyl-transferases (HATs) CREB binding protein (CREBBP) and EP300 are recurrently mutated in the activated B cell-like and germinal center (GC) B cell-like subtypes of diffuse large B cell lymphoma (DLBCL). Here, we introduced a patient mutation into a human DLBCL cell line using CRISPR and deleted Crebbp and Ep300 in the GC B cell compartment of mice. CREBBP-mutant DLBCL clones exhibited reduced histone H3 acetylation, expressed significantly less MHCII, and grew faster than wild-type clones in s.c. and orthotopic xenograft models. Mice lacking Crebbp in GC B cells exhibited hyperproliferation of their GC compartment upon immunization, had reduced MHCII surface expression on GC cells, and developed accelerated MYC-driven lymphomas. Ep300 inactivation reproduced some, but not all, consequences of Crebbp inactivation. MHCII deficiency phenocopied the effects of CREBBP loss in spontaneous and serial transplantation models of MYC-driven lymphomagenesis, supporting the idea that the mutational inactivation of CREBBP promotes immune evasion. Indeed, the depletion of CD4(+) T cells greatly facilitated the engraftment of lymphoma cells in serial transplantation models. In summary, we provide evidence that both HATs are bona fide tumor suppressors that control MHCII expression and promote tumor immune control; mutational inactivation of CREBBP, but not of EP300, has additional cell-intrinsic engraftment and growth-promoting effects

In Vivo Assessment of Cold Adaptation in Insect Larvae by Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy

Background Temperatures below the freezing point of water and the ensuing ice crystal formation pose serious challenges to cell structure and function. Consequently, species living in seasonally cold environments have evolved a multitude of strategies to reorganize their cellular architecture and metabolism, and the underlying mechanisms are crucial to our understanding of life. In multicellular organisms, and poikilotherm animals in particular, our knowledge about these processes is almost exclusively due to invasive studies, thereby limiting the range of conclusions that can be drawn about intact living systems. Methodology Given that non-destructive techniques like 1H Magnetic Resonance (MR) imaging and spectroscopy have proven useful for in vivo investigations of a wide range of biological systems, we aimed at evaluating their potential to observe cold adaptations in living insect larvae. Specifically, we chose two cold-hardy insect species that frequently serve as cryobiological model systems–the freeze-avoiding gall moth Epiblema scudderiana and the freeze-tolerant gall fly Eurosta solidaginis. Results In vivo MR images were acquired from autumn-collected larvae at temperatures between 0°C and about -70°C and at spatial resolutions down to 27 µm. These images revealed three-dimensional (3D) larval anatomy at a level of detail currently not in reach of other in vivo techniques. Furthermore, they allowed visualization of the 3D distribution of the remaining liquid water and of the endogenous cryoprotectants at subzero temperatures, and temperature-weighted images of these distributions could be derived. Finally, individual fat body cells and their nuclei could be identified in intact frozen Eurosta larvae. Conclusions These findings suggest that high resolution MR techniques provide for interesting methodological options in comparative cryobiological investigations, especially in vivo

Flow and diffusion measurements on complex fluids using dynamic NMR microscopy : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physics at Massey University

This thesis deals with the measurement of fluid motion by NMR methods and the relationship of that motion both to the molecular organisation and to the fluid boundary conditions. The theory and technique of dynamic NMR microscopy are presented. A specially designed high gradient probe for Pulsed Gradient Spin Echo (PGSE) experiments is described. First, the time evolution of electroosmotic flow in a capillary is measured. With increasing time after the application of an electrophoretic pulse a transition from plug flow to parabolic flow is found. The agreement of the measured flow profiles with theory is excellent. Next, a two-dimensional velocity exchange experiment (VEXSY) is described. Experiments on unrestricted Brownian motion, laminar circular flow in a Couette cell and flow through microspheres are performed. A major aspect of the thesis concerns molecular dynamics in semi-dilute polymer solutions close to a de-mixing transition. Therefore, a description of the Flory-Huggins model for the phase behaviour of polymer solutions is given along with a review of the literature on shear-induced effects in semi-dilute polymer solutions. PGSE experiments were performed in order to measure the temperature dependence of the self-diffusion coefficient of polystyrene in semi-dilute cyclohexane solutions near the de-mixing transition over a wide range of molar masses. The temperature dependence can be described by a Williams-Landel-Ferry (WLF) equation, characteristic of a glass transition. From the self-diffusion coefficients the values for the tube disengagement times were obtained. NMR rheology experiments were performed on semi-dilute polystyrene/cyclohexane solutions near the de-mixing transition. The flow profiles exhibit power law behaviour, and from the power law index the entanglement formation times are extracted. A consistency of the values for the entanglement formation times and tube disengagement times was found. As part of the study of polymer solutions at elevated temperatures, strong convectional effects were observed. In order to carry out diffusion measurements these effects were suppressed using better thermal equilibration. However, the convection process itself was subject to NMR investigation. Conventional flow in a capillary was measured using PGSE NMR, VEXSY and dynamic NMR microscopy. The VEXSY experiment shows that the flow is stationary. The velocity propagator measured using dynamic NMR microscopy was used to calculate the echo attenuation function E(q). It was found that the pronounced minima and maxima in the Stejskal-Tanner plots agree well with the measured E(q) values. Flow profiles of lyotropic liquid crystals are presented. Using deuterium NMR spectroscopy it is shown that the shear-induced alignment of molecules can be measured using NMR microscopy

Synthesis and characterization of cationic copolymers of butylacrylate and [3-(methacryloylamino)-propyl]trimethylammonium chloride

Cationic copolymers of butylacrylate (BA) and [3-(methacryloylamino)-propyl]trimethylammonium chloride (MAPTAC) were synthesized by free-radical-solution polymerization in methanol and ethanol. An FT-Raman Spectrometer and NMR were used to monitor the polymerization process. The copolymers were characterized by light scattering, NMR, DSC, and thermogravimetric analysis. It was found that random copolymers could be prepared, and the molar fractions of BA and cationic monomers in the copolymers were close to the feed ratios. The copolymer prepared in methanol had a higher molecular weight than that prepared in ethanol. As the cationic monomer content increased, the glass-transition temperature (Tg) of the copolymer also increased, whereas the thermal stability decreased. The reactivity ratios for the monomers were evaluated. The copolymerization of BA (M1) with MAPTAC (M2) gave reactivity ratios such as r1 = 0.92 and r2 = 2.61 in ethanol as well as r1 = 0.79 and r2 = 0.90 in methanol. This study indicated that a random copolymer containing a hydrophobic monomer (BA) and a cationic hydrophilic monomer (MAPTAC) could be prepared in a proper polar solvent such as methanol or ethanol. © 2001 John Wiley & Sons, Inc

The tumor suppressive TGF-β/SMAD1/S1PR2 signaling axis is recurrently inactivated in diffuse large B-cell lymphoma

The sphingosine-1-phosphate receptor S1PR2 and its downstream signaling pathway is commonly silenced in diffuse large B-cell lymphoma (DLBCL), either by mutational inactivation or through negative regulation by the oncogenic transcription factor FOXP1. In this study, we have examined the upstream regulators of S1PR2 expression and have newly identified the TGF-β/TGF-βR2/SMAD1 axis as critically involved in S1PR2 transcriptional activation. Phosphorylated SMAD1 directly binds to regulatory elements in the locus as assessed by chromatin immunoprecipitation, and the CRISPR-mediated genomic editing of , or in DLBCL cell lines renders cells unresponsive to TGF-β-induced apoptosis. DLBCL clones lacking any one of the three factors have a clear growth advantage in vitro, as well as in subcutaneous xenotransplantation models, and in a novel model of orthotopic growth of DLBCL cells in the spleens and bone marrow of MISTRG mice expressing various human cytokines. The loss of induces hyper-proliferation of the germinal center B-cell compartment of immunized mice and accelerates -driven lymphomagenesis in spontaneous and serial transplantation models. The specific loss of in murine GC B-cells phenocopies the effects of loss on GC B-cell hyper-proliferation. Finally, we show that SMAD1 expression is aberrantly downregulated in >85% of analyzed DLBCL patients. The combined results uncover an important novel tumor suppressive function of the TGF-β/TGF-βR2/SMAD1/S1PR2 axis in DLBCL, and show that DLBCL cells have evolved to inactivate the pathway at the level of SMAD1 expression