A metabolome genome-wide association study implicates histidine N-pi-methyltransferase as a key enzyme in N-methylhistidine biosynthesis in Arabidopsis thaliana

A genome-wide association study (GWAS), which uses information on single nucleotide polymorphisms (SNPs) from many accessions, has become a powerful approach to gene identification. A metabolome GWAS (mGWAS), which relies on phenotypic information based on metabolite accumulation, can identify genes that contribute to primary and secondary metabolite contents. In this study, we carried out a mGWAS using seed metabolomic data from Arabidopsis thaliana accessions obtained by liquid chromatography–mass spectrometry to identify SNPs highly associated with the contents of metabolites such as glucosinolates. These SNPs were present in genes known to be involved in glucosinolate biosynthesis, thus confirming the effectiveness of our analysis. We subsequently focused on SNPs detected in an unknown methyltransferase gene associated with N-methylhistidine content. Knockout and overexpression of A. thaliana lines of this gene had significantly decreased and increased N-methylhistidine contents, respectively. We confirmed that the overexpressing line exclusively accumulated histidine methylated at the pi position, not at the tau position. Our findings suggest that the identified methyltransferase gene encodes a key enzyme for N-methylhistidine biosynthesis in A. thaliana

解体新書に描かれた図譜の現代解釈 : 肝胆膵編

　解体新書は当時の日本において最先端の医学書であったが，改めて観察すると，現代医学との相違点がいくつか存在する。そこで解体新書の図譜を現代医学の視点から考察し，原図に沿って現代医学の要素をメディカルイラストレーションの手法を用いて加筆修正した。また江戸時代と現代において各臓器の見せ方の違いを考察した。本論文では解体新書の「肝臓篇」「膵臓，脾臓篇」の２章の中の，肝臓，胆嚢，膵臓の３臓器の図譜について現代医学の視点から考察して相違点を抽出した。それを基に，原図に沿って現代医学の要素を加筆修正した。加筆修正するポイントとして，臓器の構造や機能を，強調や省略を駆使して的確に表現した。また，臓器は生体的構図で描画し，関連する周囲組織も含めた構図を作成した。肝臓前面の図譜では，形状を整理し，間膜と肝円索を加筆した。肝門の図譜では，脈管を修正し，間膜と圧痕を加筆した。胆嚢の図譜では，形状と層の表現を修正し，胆嚢管の表現を修正した。膵臓の図譜では，前面と背面の２枚の図を作成した。また，肝門部を加筆，胆管と膵管を修正，胃と膵臓の前後関係を修正，脾臓の脈管を修正したうえで，腎臓を削除し，横行結腸を加筆した。Kaitai-Shinsho was one of the state-of-the-art medical books in Japan during the Edo period.However, on closer observation, there are several differences between the illustrations and modern medicine. Therefore, we nvestigated the illustrations in the Kaitai-Shinsho from a modern medical point of view, and retouched them using medical illustration techniques in accordance with the original figures. We also discussed the differences in how to show each organ in the Edo and modernperiods. Regarding the three organs of the liver, gallbladder, and pancreas, we extracted the differences and discussed from a modern medical point of view. The structures and functions of these organs that have been scientifically proven were adequately drawn through the use of emphasis and omission techniques. These organs were drawn with anatomical composition, which can be easily understood, including the relevant surrounding tissues. For the figure of “Liver: front", we 1) organized the shape of the entire liver, 2) retouched the surrounding membrane, and 3) retouched the round ligament. For the figure of “Liver: hilum", we 1) modified the vessels flowing into the liver, 2) retouched the surrounding membrane, and 3) retouched the impressions on the surface. For the figure of “Gallbladder", we 1) modified the layers of the wall, 2) retouched the shape, and 3) retouched the cystic duct. For the figure of “Pancreas", we drew two views of the pancreas front and pancreas back. In addition, we 1) retouched the hepatic hilum, 2) modified the bile duct and pancreatic duct, 3) modified the position of stomach and pancreas, 4) modified the vessels of the spleen, 5) removed the kidney, and 6) retouched the transverse colon

OAZ-t/OAZ3 Is Essential for Rigid Connection of Sperm Tails to Heads in Mouse

Polyamines are known to play important roles in the proliferation and differentiation of many types of cells. Although considerable amounts of polyamines are synthesized and stored in the testes, their roles remain unknown. Ornithine decarboxylase antizymes (OAZs) control the intracellular concentration of polyamines in a feedback manner. OAZ1 and OAZ2 are expressed ubiquitously, whereas OAZ-t/OAZ3 is expressed specifically in germline cells during spermiogenesis. OAZ-t reportedly binds to ornithine decarboxylase (ODC) and inactivates ODC activity. In a prior study, polyamines were capable of inducing a frameshift at the frameshift sequence of OAZ-t mRNA, resulting in the translation of OAZ-t. To investigate the physiological role of OAZ-t, we generated OAZ-t–disrupted mutant mice. Homozygous OAZ-t mutant males were infertile, although the polyamine concentrations of epididymides and testes were normal in these mice, and females were fertile. Sperm were successfully recovered from the epididymides of the mutant mice, but the heads and tails of the sperm cells were easily separated in culture medium during incubation. Results indicated that OAZ-t is essential for the formation of a rigid junction between the head and tail during spermatogenesis. The detached tails and heads were alive, and most of the headless tails showed straight forward movement. Although the tailless sperm failed to acrosome-react, the heads were capable of fertilizing eggs via intracytoplasmic sperm injection. OAZ-t likely plays a key role in haploid germ cell differentiation via the local concentration of polyamines

Hierarchical

prevention