The YlmG protein has a conserved function related to the distribution of nucleoids in chloroplasts and cyanobacteria

<p>Abstract</p> <p>Background</p> <p>Reminiscent of their free-living cyanobacterial ancestor, chloroplasts proliferate by division coupled with the partition of nucleoids (DNA-protein complexes). Division of the chloroplast envelope membrane is performed by constriction of the ring structures at the division site. During division, nucleoids also change their shape and are distributed essentially equally to the daughter chloroplasts. Although several components of the envelope division machinery have been identified and characterized, little is known about the molecular components/mechanisms underlying the change of the nucleoid structure.</p> <p>Results</p> <p>In order to identify new factors that are involved in the chloroplast division, we isolated <it>Arabidopsis thaliana </it>chloroplast division mutants from a pool of random cDNA-overexpressed lines. We found that the overexpression of a previously uncharacterized gene (<it>AtYLMG1-1</it>) of cyanobacterial origin results in the formation of an irregular network of chloroplast nucleoids, along with a defect in chloroplast division. In contrast, knockdown of <it>AtYLMG1-1 </it>resulted in a concentration of the nucleoids into a few large structures, but did not affect chloroplast division. Immunofluorescence microscopy showed that AtYLMG1-1 localizes in small puncta on thylakoid membranes, to which a subset of nucleoids colocalize. In addition, in the cyanobacterium <it>Synechococcus elongates</it>, overexpression and deletion of <it>ylmG </it>also displayed defects in nucleoid structure and cell division.</p> <p>Conclusions</p> <p>These results suggest that the proper distribution of nucleoids requires the YlmG protein, and the mechanism is conserved between cyanobacteria and chloroplasts. Given that <it>ylmG </it>exists in a cell division gene cluster downstream of <it>ftsZ </it>in gram-positive bacteria and that <it>ylmG </it>overexpression impaired the chloroplast division, the nucleoid partitioning by YlmG might be related to chloroplast and cyanobacterial division processes.</p

Assessment of skin inflammation using near-infrared Raman spectroscopy combined with artificial intelligence analysis in an animal model

Raman spectroscopy is a powerful method for estimating the molecular structure of a target that can be adapted for biomedical analysis given its non-destructive nature. Inflammatory skin diseases impair the skin’s barrier function and interfere with the patient’s quality of life. There are limited methods for non-invasive and objective assessment of skin inflammation. We examined whether Raman spectroscopy can be used to predict skin inflammation with high sensitivity and specificity when combined with artificial intelligence (AI) analysis. Inflammation was chemically induced in mouse ears, and Raman spectra induced by a 785 nm laser were recorded. A principal component (PC) analysis of the Raman spectra was performed to extract PCs with the highest percentage of variance and to estimate the statistical score. The accuracy in predicting inflammation based on the Raman spectra with or without AI analysis was assessed using receiver operating characteristic (ROC) curves. We observed some typical changes in the Raman spectra upon skin inflammation, which may have resulted from vasodilation and interstitial oedema. The estimated statistical scores based on spectral changes correlated with the histopathological changes in the skin. The ROC curve based on PC2, which appeared to include some spectral features, revealed a maximum accuracy rate of 80.0% with an area under the curve (AUC) of 0.864. The AI analysis improved the accuracy rate to 93.1% with an AUC of 0.972. The current findings demonstrate that the combination of Raman spectroscopy with near-infrared excitation and AI analysis can provide highly accurate information on the pathology of skin inflammation

Effects of Bepridil on Spiral Reentry

Bepridil is effective for conversion of atrial fibrillation to sinus rhythm and in the treatment of drug-refractory ventricular tachyarrhythmias. We investigated the effects of bepridil on electrophysiological properties and spiral-wave (SW) reentry in a 2-dimensional ventricular muscle layer of isolated rabbit hearts by optical mapping. Ventricular tachycardia (VT) induced in the presence of bepridil (1 μM) terminated earlier than in the control. Bepridil increased action potential duration (APD) by 5% – 8% under constant pacing and significantly increased the space constant. There was a linear relationship between the wavefront curvature (κ) and local conduction velocity: LCV = LCV0 − D·κ (D, diffusion coefficient; LCV0, LCV at κ = 0). Bepridil significantly increased D and LCV0. The regression lines with and without bepridil crossed at κ = 20 – 40 cm−1, resulting in a paradoxical decrease of LCV at κ > 40 cm−1. Dye transfer assay in cultured rat cardiomyocytes confirmed that bepridil increased intercellular coupling. SW reentry in the presence of bepridil was characterized by decremental conduction near the rotation center, prominent drift, and self-termination by collision with boundaries. These results indicate that bepridil causes an increase of intercellular coupling and a moderate APD prolongation, and this combination compromises wavefront propagation near the rotation center of SW reentry, leading to its drift and early termination

IKs Block and Spiral-Wave Reentry

We tested a hypothesis that an enhancement of IKs may play a pivotal role in ventricular proarrhythmia under high sympathetic activity. A 2-dimensional ventricular muscle layer was prepared in rabbit hearts, and action potential signals were analyzed by optical mapping. During constant stimulation, isoproterenol (ISP, 0.1 μM) significantly shortened action potential duration (APD); chromanol 293B (30 μM), a selective IKs-blocker, reversed the APD shortening. VTs induced in the presence of ISP lasted longer than in the control, and this was reversed by 293B. E-4031 (0.1 μM), a selective IKr-blocker, did not cause such reversal. Spiral-wave (SW) reentry with ISP was characterized by more stable rotation around a shorter functional block line (FBL) than in the control. After application of 293B, SW reentry was destabilized, and rotation around a longer FBL with prominent drift reappeared. The APD abbreviation by ISP close to the rotation center was more pronounced than in the periphery, leading to an opposite APD gradient (center < periphery) compared with controls. This effect was also reversed by 293B. In conclusion, β-adrenergic stimulation stabilizes SW reentry most likely though an enhancement of IKs. Blockade of IKs may be a promising therapeutic modality in prevention of ventricular tachyarrhythmias under high sympathetic activity

RiceFOX: A Database of Arabidopsis Mutant Lines Overexpressing Rice Full-Length cDNA that Contains a Wide Range of Trait Information to Facilitate Analysis of Gene Function

Identification of gene function is important not only for basic research but also for applied science, especially with regard to improvements in crop production. For rapid and efficient elucidation of useful traits, we developed a system named FOX hunting (Full-length cDNA Over-eXpressor gene hunting) using full-length cDNAs (fl-cDNAs). A heterologous expression approach provides a solution for the high-throughput characterization of gene functions in agricultural plant species. Since fl-cDNAs contain all the information of functional mRNAs and proteins, we introduced rice fl-cDNAs into Arabidopsis plants for systematic gain-of-function mutation. We generated >30,000 independent Arabidopsis transgenic lines expressing rice fl-cDNAs (rice FOX Arabidopsis mutant lines). These rice FOX Arabidopsis lines were screened systematically for various criteria such as morphology, photosynthesis, UV resistance, element composition, plant hormone profile, metabolite profile/fingerprinting, bacterial resistance, and heat and salt tolerance. The information obtained from these screenings was compiled into a database named ‘RiceFOX’. This database contains around 18,000 records of rice FOX Arabidopsis lines and allows users to search against all the observed results, ranging from morphological to invisible traits. The number of searchable items is approximately 100; moreover, the rice FOX Arabidopsis lines can be searched by rice and Arabidopsis gene/protein identifiers, sequence similarity to the introduced rice fl-cDNA and traits. The RiceFOX database is available at http://ricefox.psc.riken.jp/

Chronic Reduction of GIP Secretion Alleviates Obesity and Insulin Resistance Under High-Fat Diet Conditions.

Gastric inhibitory polypeptide (GIP) exhibits potent insulinotropic effects on β-cells and anabolic effects on bone formation and fat accumulation. We explored the impact of reduced GIP levels in vivo on glucose homeostasis, bone formation, and fat accumulation in a novel GIP-GFP knock-in (KI) mouse. We generated GIP-GFP KI mice with a truncated prepro-GIP gene. The phenotype was assessed in heterozygous and homozygous states in mice on a control fat diet and a high-fat diet (HFD) in vivo and in vitro. Heterozygous GIP-GFP KI mice (GIP-reduced mice [GIP(gfp/+)]) exhibited reduced GIP secretion; in the homozygous state (GIP-lacking mice [GIP(gfp/gfp)]), GIP secretion was undetectable. When fed standard chow, GIP(gfp/+) and GIP(gfp/gfp) mice showed mild glucose intolerance with decreased insulin levels; bone volume was decreased in GIP(gfp/gfp) mice and preserved in GIP(gfp/+) mice. Under an HFD, glucose levels during an oral glucose tolerance test were similar in wild-type, GIP(gfp/+), and GIP(gfp/gfp) mice, while insulin secretion remained lower. GIP(gfp/+) and GIP(gfp/gfp) mice showed reduced obesity and reduced insulin resistance, accompanied by higher fat oxidation and energy expenditure. GIP-reduced mice demonstrate that partial reduction of GIP does not extensively alter glucose tolerance, but it alleviates obesity and lessens the degree of insulin resistance under HFD conditions, suggesting a potential therapeutic value