213 research outputs found
The space of non-extendable quasimorphisms
For a pair of a group and its normal subgroup , we consider
the space of quasimorphisms and quasi-cocycles on non-extendable to . To
treat this space, we establish the five-term exact sequence of cohomology
relative to the bounded subcomplex. As its application, we study the spaces
associated with the kernel of the (volume) flux homomorphism, the
IA-automorphism group of a free group, and certain normal subgroups of Gromov
hyperbolic groups.
Furthermore, we employ this space to prove that the stable commutator length
is equivalent to the stable mixed commutator length for certain pairs of a
group and its normal subgroup.Comment: 58 pages, 1 figure. Major revision. Theorem 1.12 in v3 has been
generalized to Theorem 1.2 in the current version: this new theorem treats
hyperbolic mapping tori in general cases, and it serves as a leading
application of our main theore
Effects of Imipramine and Lithium on the Suppression of Cell Proliferation in the Dentate Gyrus of the Hippocampus in Adrenocorticotropic Hormone-treated Rats
We examined the influence of chronic adrenocorticotropic hormone (ACTH) treatment on the number of Ki-67-positive cells in the dentate gyrus of the hippocampus in rats. ACTH treatment for 14 days decreased the number of such cells. The administration of imipramine or lithium alone for 14 days had no effect in saline-treated rats. The effect of ACTH was blocked by the administration of imipramine. Furthermore, the coadministration of imipramine and lithium for 14 days significantly increased the number of Ki-67-positive cells in both the saline and ACTH-treated rats. The coadministration of imipramine and lithium normalized the cell proliferation in the dentate gyrus of the hippocampus in rats treated with ACTH
Coarse group theoretic study on stable mixed commutator length
Let be a group and a normal subgroup of . We study the large scale
behavior, not the exact values themselves, of the stable mixed commutator
length on the mixed commutator subgroup ; when ,
equals the stable commutator length on the commutator
subgroup . For this purpose, we regard not only as a
function from to , but as a bi-invariant metric
function from to .
Our main focus is coarse group theoretic structures of
. Our preliminary result (the absolute version)
connects, via the Bavard duality, and the quotient
vector space of the space of -invariant quasimorphisms on over one of
such homomorphisms. In particular, we prove that the dimension of this vector
space equals the asymptotic dimension of .
Our main result is the comparative version: we connect the coarse kernel,
formulated by Leitner and Vigolo, of the coarse homomorphism ; , and a certain
quotient vector space of the space of invariant quasimorphisms. Assume
that and that is finite dimensional with dimension .
Then we prove that the coarse kernel of is isomorphic to
as a coarse group. In contrast to the absolute version, the
space is finite dimensional in many cases, including all with
finitely generated and nilpotent . As an application of our result,
given a group homomorphism between finitely generated
groups, we define an -linear map `inside' the groups, which is dual
to the naturally defined -linear map from to
induced by .Comment: 69 pages, no figure. Minor revision (v2): some symbols change
Affleck-Dine leptogenesis via multiscalar evolution in a supersymmetric seesaw model
A leptogenesis scenario in a supersymmetric standard model extended with
introducing right-handed neutrinos is reconsidered. Lepton asymmetry is
produced in the condensate of a right-handed sneutrino via the Affleck-Dine
mechanism. The LH_u direction develops large value due to a negative effective
mass induced by the right-handed sneutrino condensate through the Yukawa
coupling of the right-handed neutrino, even if the minimum during the inflation
is fixed at the origin. The lepton asymmetry is nonperturbatively transfered to
the LH_u direction by this Yukawa coupling.Comment: 19 pages, 3 figures. Revised version for publication. The model was
modified to fix some problem
Specific Recognition of Linear Ubiquitin Chains by NEMO Is Important for NF-κB Activation
Activation of nuclear factor-κB (NF-κB), a key mediator of inducible transcription in immunity, requires binding of NF-κB essential modulator (NEMO) to ubiquitinated substrates. Here, we report that the UBAN (ubiquitin binding in ABIN and NEMO) motif of NEMO selectively binds linear (head-to-tail) ubiquitin chains. Crystal structures of the UBAN motif revealed a parallel coiled-coil dimer that formed a heterotetrameric complex with two linear diubiquitin molecules. The UBAN dimer contacted all four ubiquitin moieties, and the integrity of each binding site was required for efficient NF-κB activation. Binding occurred via a surface on the proximal ubiquitin moiety and the canonical Ile44 surface on the distal one, thereby providing specificity for linear chain recognition. Residues of NEMO involved in binding linear ubiquitin chains are required for NF-κB activation by TNF-α and other agonists, providing an explanation for the detrimental effect of NEMO mutations in patients suffering from X-linked ectodermal dysplasia and immunodeficiency
Structural Basis of the Autophagy-Related LC3/Atg13 LIR Complex: Recognition and Interaction Mechanism
SummaryAutophagy is a bulk degradation pathway that removes cytosolic materials to maintain cellular homeostasis. The autophagy-related gene 13 (Atg13) and microtubule associate protein 1 light chain 3 (LC3) proteins are required for autophagosome formation. We demonstrate that each of the human LC3 isoforms (LC3A, LC3B, and LC3C) interacts with Atg13 via the LC3 interacting region (LIR) of Atg13. Using X-ray crystallography, we solved the macromolecular structures of LC3A and LC3C, along with the complex structures of the LC3 isoforms with the Atg13 LIR. Together, our structural and binding analyses reveal that the side-chain of Lys49 of LC3 acts as a gatekeeper to regulate binding of the LIR. We verified this observation by mutation of Lys49 in LC3A, which significantly reduces LC3A positive puncta formation in cultured cells. Our results suggest that specific affinity of the LC3 isoforms to the Atg13 LIR is required for proper autophagosome formation
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