Dust Size Growth and Settling in a Protoplanetary Disk

We have studied dust evolution in a quiescent or turbulent protoplanetary disk by numerically solving coagulation equation for settling dust particles, using the minimum mass solar nebular model. As a result, if we assume an ideally quiescent disk, the dust particles settle toward the disk midplane to form a gravitationally unstable layer within 2x10^3 - 4x10^4 yr at 1 - 30 AU, which is in good agreement with an analytic calculation by Nakagawa, Sekiya, & Hayashi (1986) although they did not take into account the particle size distribution explicitly. In an opposite extreme case of a globally turbulent disk, on the other hand, the dust particles fluctuate owing to turbulent motion of the gas and most particles become large enough to move inward very rapidly within 70 - 3x10^4 yr at 1 - 30 AU, depending on the strength of turbulence. Our result suggests that global turbulent motion should cease for the planetesimal formation in protoplanetary disks.Comment: 27 pages, 8 figures, accepted for publication in the Ap

Heme-dependent autophosphorylation of a heme sensor kinase, ChrS, from Corynebacterium diphtheriae reconstituted in proteoliposomes

AbstractCorynebacterium diphteriae employs the response regulator, ChrA, and the sensor kinase, ChrS, of a two-component signal transduction system to utilize host heme iron. Although ChrS is predicted to encode a heme sensor, the sensing mechanism remains to be characterized. In this report, ChrS expressed in Eshcherichia coli membranes was solubilized and purified using decylmaltoside. ChrS protein incorporated into proteoliposomes catalyzed heme-dependent autophosphorylation by ATP. Other metalloporphyrins and iron did not stimulate kinase activity. The UV–Vis spectrum of hemin in the ChrS–proteoliposomes indicated that heme directly interacts with ChrS. This is the first functional reconstitution of a bacterial heme-sensing protein

Evolutionary histories of breast cancer and related clones

乳がん発生の進化の歴史を解明 --ゲノム解析による発がんメカニズムの探索--. 京都大学プレスリリース. 2023-07-28.Tracking the ol' mutation trail: Unraveling the long history of breast cancer formation. 京都大学プレスリリース. 2023-08-31.Recent studies have documented frequent evolution of clones carrying common cancer mutations in apparently normal tissues, which are implicated in cancer development1, 2, 3. However, our knowledge is still missing with regard to what additional driver events take place in what order, before one or more of these clones in normal tissues ultimately evolve to cancer. Here, using phylogenetic analyses of multiple microdissected samples from both cancer and non-cancer lesions, we show unique evolutionary histories of breast cancers harbouring der(1;16), a common driver alteration found in roughly 20% of breast cancers. The approximate timing of early evolutionary events was estimated from the mutation rate measured in normal epithelial cells. In der(1;16)(+) cancers, the derivative chromosome was acquired from early puberty to late adolescence, followed by the emergence of a common ancestor by the patient’s early 30s, from which both cancer and non-cancer clones evolved. Replacing the pre-existing mammary epithelium in the following years, these clones occupied a large area within the premenopausal breast tissues by the time of cancer diagnosis. Evolution of multiple independent cancer founders from the non-cancer ancestors was common, contributing to intratumour heterogeneity. The number of driver events did not correlate with histology, suggesting the role of local microenvironments and/or epigenetic driver events. A similar evolutionary pattern was also observed in another case evolving from an AKT1-mutated founder. Taken together, our findings provide new insight into how breast cancer evolves

Genomic characterization of biliary tract cancers identifies driver genes and predisposing mutations

Background & Aims Biliary tract cancers (BTCs) are clinically and pathologically heterogeneous and respond poorly to treatment. Genomic profiling can offer a clearer understanding of their carcinogenesis, classification and treatment strategy. We performed large-scale genome sequencing analyses on BTCs to investigate their somatic and germline driver events and characterize their genomic landscape. Methods We analyzed 412 BTC samples from Japanese and Italian populations, 107 by whole-exome sequencing (WES), 39 by whole-genome sequencing (WGS), and a further 266 samples by targeted sequencing. The subtypes were 136 intrahepatic cholangiocarcinomas (ICCs), 101 distal cholangiocarcinomas (DCCs), 109 peri-hilar type cholangiocarcinomas (PHCs), and 66 gallbladder or cystic duct cancers (GBCs/CDCs). We identified somatic alterations and searched for driver genes in BTCs, finding pathogenic germline variants of cancer-predisposing genes. We predicted cell-of-origin for BTCs by combining somatic mutation patterns and epigenetic features. Results We identified 32 significantly and commonly mutated genes including TP53 , KRAS , SMAD4 , NF1 , ARID1A , PBRM1 , and ATR , some of which negatively affected patient prognosis. A novel deletion of MUC17 at 7q22.1 affected patient prognosis. Cell-of-origin predictions using WGS and epigenetic features suggest hepatocyte-origin of hepatitis-related ICCs. Deleterious germline mutations of cancer-predisposing genes such as BRCA1 , BRCA2 , RAD51D , MLH1 , or MSH2 were detected in 11% (16/146) of BTC patients. Conclusions BTCs have distinct genetic features including somatic events and germline predisposition. These findings could be useful to establish treatment and diagnostic strategies for BTCs based on genetic information. Lay summary We here analyzed genomic features of 412 BTC samples from Japanese and Italian populations. A total of 32 significantly and commonly mutated genes were identified, some of which negatively affected patient prognosis, including a novel deletion of MUC17 at 7q22.1 . Cell-of-origin predictions using WGS and epigenetic features suggest hepatocyte-origin of hepatitis-related ICCs. Deleterious germline mutations of cancer-predisposing genes were detected in 11% of patients with BTC. BTCs have distinct genetic features including somatic events and germline predisposition

モモのさし木繁殖に関する基礎的研究 II : 緑枝ざしにおける IBA の発根促進効果(農学部門)

モモの緑枝ざしにおいて, 化学物質ならびにさし穂の形態的処理を行なったところ, IBA 25 p. p. m.処理で発根率は62.8%と最も優れ, さらにさし穂を10cm長・半分剪除の4葉に調整した場合, 83.3%の発根率を得たが, 平均根乾物重は10cm長・4葉に調整したさし穂に劣った。置床期間中のさし穂内全炭水化物はIBA処理区で顕著な減少傾向がみられ, 無処理区とは対照的に基部含量が上部含量を上回って推移した。でん粉も同様な傾向がうかがえたが, シュクローズおよびソルビトールはIBA処理区のさし穂基部において, 置床直後より増加したのが顕著であった。^CO_2を置床期間中漸次さし穂最上葉に取り込ませ, ^C標識同化産物の転流を調査した結果, IBA処理はさし木当初より同化産物の基部転流を促すのではなく, 同処理区においては発根の一週間前ころよりさし穂基部でのラベル比が高くなった。Treating the bases of cuttings with 25p.p.m. IBA promoted rooting, 62.8% rooted, on the softwood cuttings of peach. A rooting of 83.3% was obtained with the cuttings prepared 10cm length・four leaves cut off half, whereas less average of dry weight of root were produced rather than the cuttings prepared 10cm length・four leaves. The total carbohydrate content in the cuttings decreased, remarkably when IBA treated, throughout planting period and it was observed on IBA-treated cuttings that the basal stem content was higher than the upper stem in contrast with untreated cuttings. Changes in starch in the cuttings during planting period was similar, although contents of sucrose and sorbitol on the basal stem increased rapidly at the first stage of planting period. Investigating the translocation of photosynthate after administration of ^CO_2 to the upper leaf of IBA-treated and untreated cuttings at different times during planting period, IBA did not accelerate the basipetal translocation of ^C-photosynthate immediately after planting. ^C-labeled assimilate, however, enhanced on the basal stem of IBA-treated cuttings since a week before root appearance

ゲンシタイヨウケイニオケルビショウワクセイシュウダンノトウケイテキフルマイ

京都大学0048新制・課程博士理学博士甲第2113号理博第539号新制||理||289(附属図書館)5972UT51-53-M93京都大学大学院理学研究科物理学第二専攻(主査)教授 林 忠四郎, 教授 長谷川 博一, 教授 玉垣 良三学位規則第5条第1項該当Kyoto UniversityDA