Language：English   Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science (PLoS)  

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy (HAM) after a long latent period in a fraction of infected individuals. These HTLV-1-infected cells typically have phenotypes similar to that of CD4⁺T cells, but the cell status is not well understood. To extract the inherent information of HTLV-1-infected CD4⁺ cells, we integratively analyzed the ATAC-seq and RNA-seq data of the infected cells. Compared to CD4⁺T cells from healthy donors, we found anomalous chromatin accessibility in HTLV-1infected CD4⁺ cells derived from ATL cases in terms of location and sample-to-sample fluctuations in open chromatin regions. Further, by focusing on systematically selected genes near the open chromatin regions, we quantified the difference between the infected CD4⁺ cells in ATL cases and healthy CD4⁺T cells in terms of the correlation between the chromatin structures and the gene expressions. Based on a further analysis of chromatin accessibility, we detected TLL1 (Tolloid Like 1) as one of the key genes that exhibit unique gene expressions in ATL cases. A luciferase assay indicated that TLL1 has an isoform-dependent regulatory effect on TGF-β. Overall, this study provides results about the status of HTLV-1-infected cells, which are qualitatively consistent across the different scales of chromatin accessibility, transcription, and immunophenotype.

DOI： 10.1371/journal.pcbi.1012690

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Publisher：Tokyo Journal of Mathematics  

An integral binary quartic form is said to be locally soluble (resp. soluble) if the corresponding genus one curve has a rational point over Qv for every place v of Q (resp. over Q). We consider the proportion of soluble integral binary quartic forms in locally soluble forms. Bhargava showed the proportion is positive when one considers all binary quartics, and Bhargava–Ho proved the proportion is zero for a subfamily. In this paper, we estimate the proportions for some other subfamilies. It relies on results for elliptic curves y2 = x3 − n2x by Heath-Brown, Xiong–Zaharescu and Smith.

DOI： 10.3836/tjm/1502179411

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：World Scientific Pub Co Pte Ltd  

We study a variant of the Hasse principle for finite Galois modules, allowing exceptional sets of positive density. For a Galois module whose underlying abelian group is isomorphic to [Formula: see text] ([Formula: see text]), we show that the product of the restriction maps for places in a set of places [Formula: see text] is injective if the Dirichlet density of [Formula: see text] is strictly larger than [Formula: see text]. We give applications to the local–global divisibility problem for elliptic curves and the Hasse principle for flexes on plane cubic curves.

DOI： 10.1142/S179304212250097X

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Language：English   Publishing type：Research paper (scientific journal)  

The aim of this short note is to report some progress on numerical computations of algebraic Witt
vectors over imaginary quadratic fields K based on a previous work of the second author. In partic-
ular, when K is of class number one, we describe an effective procedure to decide whether a given
algebraic Witt vector ξ∈EK =K ⊗WaOK (O ̄K)is an integral Witt vector ξ∈WaOK (O ̄K).

DOI： https://doi.org/10.35011/risc.21-16

Language：Japanese   Publishing type：Research paper (scientific journal)  

The huge amount of data acquired by high-throughput sequencing requires data reduction for effective analysis. Here we give a clustering algorithm for genome-wide open chromatin data using a new data reduction method. This method regards the genome as a string of 1s and 0s based on a set of peaks and calculates the Hamming distances between the strings. This algorithm with the systematically optimized set of peaks enables us to quantitatively evaluate differences between samples of hematopoietic cells and classify cell types, potentially leading to a better understanding of leukemia pathogenesis.

DOI： 10.1371/journal.pcbi.1008422

Language：English   Publishing type：Research paper (scientific journal)  

We give two algorithms to compute linear determinantal representations of
smooth plane curves of any degree over any field. As particular examples, we
explicitly give representatives of all equivalence classes of linear
determinantal representations of two special quartics over the field
$mathbb{Q}$ of rational numbers, the Klein quartic and the Fermat quartic.
This paper is a summary of third author's talk at the JSIAM JANT workshop on
algorithmic number theory in March 2018. Details will appear elsewhere.

DOI： 10.14495/jsiaml.11.9

Language：English   Publishing type：Research paper (scientific journal)  

The local-global principle for symmetric determinantal representations of smooth plane curves in characteristic two
We give an application of Mumford's theory of canonical theta characteristics to a Diophantine problem in characteristic two. We prove that a smooth plane curve over a global field of characteristic two is defined by the determinant of a symmetric matrix with entries in linear forms in three variables if and only if such a symmetric determinantal representation exists everywhere. locally. It is a special feature in characteristic two because analogous results are not true in other characteristics. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jpaa.2016.09.013

Language：English   Publishing type：Research paper (scientific journal)  

The local-global principle for symmetric determinantal representations of smooth plane curves
A smooth plane curve is said to admit a symmetric determinantal representation if it can be defined by the determinant of a symmetric matrix with entries in linear forms in three variables. We study the local-global principle for the existence of symmetric determinantal representations of smooth plane curves over a global field of characteristic different from two. When the degree of the plane curve is less than or equal to three, we relate the problem of finding symmetric determinantal representations to more familiar Diophantine problems on the Severi-Brauer varieties and mod 2 Galois representations, and prove that the local-global principle holds for conics and cubics. We also construct counterexamples to the local-global principle for quartics using the results of Mumford, Harris, and Shioda on theta characteristics.

DOI： 10.1007/s11139-016-9775-3

Language：English   Publishing type：Research paper (scientific journal)  

We prove that the defining equations of the Fermat curves of prime degree cannot be written as the determinant of symmetric matrices with entries in linear forms in three variables with rational coefficients. In the proof, we use a relation between symmetric matrices with entries in linear forms and non-effective theta characteristics on smooth plane curves. We also use some results of Gross-Rohrlich on the rational torsion points on the Jacobian varieties of the Fermat curves of prime degree.

DOI： 10.1142/S1793042116500597

Language：Japanese  

Complete intersection of two quadrics and Galois cohomology : a research announcement (Algebraic Number Theory and Related Topics 2012)
In this paper, we give an overview of a method of explicit 2-descent for hyperelliptic Jacobian varieties ([1]), and relate it to the set of complete intersections of two quadrics. This is an announcement of the results contained in the paper [4].

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.2748/tmj/1365452627

Event date： 2021.9

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Arithmetic geometry of some plane quartics, Yasuhiro Ishitsuka, Kyushu university algebra seminar

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Arithmetic of rotationally symmetric determinantal representations

Language：English  

Country：Other  

Language：English  

Country：Other  

Computation on linear determinantal representations

Language：English  

Country：Other  

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：1