Pericarp Characteristics of the F(1) Hybrid Medium-Fruited Tomato between the Male Sterile Mutant (T-4) of the Large-Fruited 'First' and a Small-Fruited Pure Line with Soft Pericarp

Breeding for a soft pericarp in medium-sized tomato fruit was conducted by crossing the male sterile mutant (T-4) of the large-fruited 'First' and a small-fruited pure line with a soft pericarp (S). Pericarp characteristics of the F(1) hybrid (named MS-II) were compared with the parents and two similar medium-fruited tomato cultivars, 'Red ore' and 'Frutica'. Pericarp firmness in MS-II was lower as compared with that of both T-4 and S. Differences in pericarp firmness among MS-II, 'Red ore' and 'Frutica' were dependent on truss. In the first truss, MS-II developed fruits with a softer pericarp than 'Red ore', but with a firmer pericarp than 'Frutica'. In the second and third trusses, pericarp firmness of the fruit in MS-II tended to be lower than those of the other two cultivars. The thickness of the exocarp cuticle in MS-II was lower than that in 'Red ore', but was no different to that in 'Frutica'. Thus genotypic differences in pericarp firmness among MS-II, 'Red ore' and 'Frutica' seem to be derived from differences in the degree of cutin development in the epidermal perimeter. A thinner cuticle can explain pericarp softness in the fruits above the second truss in MS-II.薄皮果柔の中玉トマト品種育成を目的とし，‘ファースト’花粉非崩壊型雄性不稔系統 (T-4) を種子親，果皮の軟らかい小果固定系統 (S) を花粉親とするF(1)雑種 (MS-II) の特性について，両親系統および既存の中玉F(1)品種‘レッドオーレ’，‘フルティカ’のそれと比較した．両親系統と比較したところ，MS-IIの果実硬度は花粉親である軟果皮Sと同等となり，果皮硬度はSよりも低い値となった．3段摘心栽培において，MS-IIの果実硬度は第1段では2品種と差は無かったが，上位果房ほど両品種よりも低くなる傾向を示した．果皮硬度は，第1果房では‘レッドオーレ’よりも低く，‘フルティカ’よりも高かったが，上位果房ほど両品種よりも低い値となる傾向を示した．MS-IIの外果皮におけるクチクラ厚を測定したところ，‘フルティカ’と同等となり，‘レッドオーレ’よりも低かった．また，MS-IIのクチクラ層の発達程度が2品種よりも低いことが観察され，MS-IIの果皮硬度が2品種よりも低い傾向を示すのは，外果皮におけるクチクラ層の発達程度が低いためと推測された

Systematic phenome analysis of Escherichia coli multiple-knockout mutants reveals hidden reactions in central carbon metabolism

Central carbon metabolism is a basic and exhaustively analyzed pathway. However, the intrinsic robustness of the pathway might still conceal uncharacterized reactions. To test this hypothesis, we constructed systematic multiple-knockout mutants involved in central carbon catabolism in Escherichia coli and tested their growth under 12 different nutrient conditions. Differences between in silico predictions and experimental growth indicated that unreported reactions existed within this extensively analyzed metabolic network. These putative reactions were then confirmed by metabolome analysis and in vitro enzymatic assays. Novel reactions regarding the breakdown of sedoheptulose-7-phosphate to erythrose-4-phosphate and dihydroxyacetone phosphate were observed in transaldolase-deficient mutants, without any noticeable changes in gene expression. These reactions, triggered by an accumulation of sedoheptulose-7-phosphate, were catalyzed by the universally conserved glycolytic enzymes ATP-dependent phosphofructokinase and aldolase. The emergence of an alternative pathway not requiring any changes in gene expression, but rather relying on the accumulation of an intermediate metabolite may be a novel mechanism mediating the robustness of these metabolic networks

Enzymatic measurement of short-chain fatty acids and application in periodontal disease diagnosis.

Periodontal disease is a chronic inflammatory condition caused by periodontal pathogens in the gingival sulcus. Short-chain fatty acids (SCFAs) produced by causal bacteria are closely related to the onset and progression of periodontal disease and have been reported to proliferate in the periodontal sulcus of patients experiencing this pathology. In such patients, propionic acid (C3), butyric acid (C4), isobutyric acid (IC4), valeric acid (C5), isovaleric acid (IC5), and caproic acid (C6), henceforth referred to as [C3-C6], has been reported to have a detrimental effect, while acetic acid (C2) exhibits no detrimental effect. In this study, we established an inexpensive and simple enzymatic assay that can fractionate and measure these acids. The possibility of applying this technique to determine the severity of periodontal disease by adapting it to specimens collected from humans has been explored. We established an enzyme system using acetate kinase and butyrate kinase capable of measuring SCFAs in two fractions, C2 and [C3-C6]. The gingival crevicular fluid (GCF) and saliva of 10 healthy participants and 10 participants with mild and severe periodontal disease were measured using the established enzymatic method and conventional gas chromatography-mass spectrometry (GC-MS). The quantification of C2 and [C3-C6] in human GCF and saliva was well correlated when using the GC-MS method. Furthermore, both C2 and [C3-C6] in the GCF increased with disease severity. However, while no significant difference was observed between healthy participants and periodontal patients when using saliva, [C3-C6] significantly differed between mild and severe periodontal disease. The enzymatic method was able to measure C2 and [C3-C6] separately as well as using the GC-MS method. Furthermore, the C2 and [C3-C6] fractions of GCF correlated with disease severity, suggesting that this method can be applied clinically. In contrast, the quantification of C2 and [C3-C6] in saliva did not differ significantly between healthy participants and patients with periodontal disease. Future studies should focus on inflammation rather than on tissue destruction