Effects of Fcj1-Mos1 and mitochondrial division on aggregation of mitochondrial DNA nucleoids and organelle morphology

Mitochondrial DNA (mtDNA) is packaged into DNA–protein complexes called nucleoids, which are distributed as many small foci in mitochondria. Nucleoids are crucial for the biogenesis and function of mtDNA. Here, using a yeast genetic screen for components that control nucleoid distribution and size, we identify Fcj1 and Mos1, two evolutionarily conserved mitochondrial proteins that maintain the connection between the cristae and boundary membranes. These two proteins are also important for establishing tubular morphology of mitochondria, as mitochondria lacking Fcj1 and Mos1 form lamellar sheets. We find that nucleoids aggregate, increase in size, and decrease in number in fcj1∆ and mos1∆ cells. In addition, Fcj1 form punctate structures and localized adjacent to nucleoids. Moreover, connecting mitochondria by deleting the DNM1 gene required for organelle division enhances aggregation of mtDNA nucleoids in fcj1∆ and mos1∆ cells, whereas single deletion of DNM1 does not affect nucleoids. Conversely, deleting F1Fo-ATP synthase dimerization factors generates concentric ring-like cristae, restores tubular mitochondrial morphology, and suppresses nucleoid aggregation in these mutants. Our findings suggest an unexpected role of Fcj1-Mos1 and organelle division in maintaining the distribution and size of mtDNA nucleoids.     

Studies on Griseolic Acid Derivatives X. Synthesis and Phosphodiesterase Inhibitory Activity of 2-Substituted Derivatives of Griseolic Acid

Abstract

Griseolic acid derivatives which were modified at the 2-and/or 6-positions were first synthesized from griseolic acid by a ring opening—reclosure reaction of the adenine ring. Among these derivatives, the 2-amino-6-deamino-6-hydroxyl (guanine) derivative showed 3.3 and 45 times stronger inhibitory activity against cAMP and cGMP PDE, respectively, than those of griseolic acid. Structure-activity relationships among these derivatives are also discussed.     

Simultaneous increases in the levels of compatible solutes by cost-effective cultivation of Synechocystis sp. PCC 6803

Synechocystis sp. PCC 6803, a cyanobacterium widely used for basic research, is often cultivated in a synthetic medium, BG-11, in the presence of 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid (HEPES) or 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid buffer. Owing to the high cost of HEPES buffer (96.9% of the total cost of BG-11 medium), the biotechnological application of BG-11 is limited. In this study, we cultured Synechocystis sp. PCC 6803 cells in BG-11 medium without HEPES buffer and examined the effects on the primary metabolism. Synechocystis sp. PCC 6803 cells could grow in BG-11 medium without HEPES buffer after adjusting for nitrogen sources and light intensity; the production rate reached 0.54 g cell dry weight·L⁻¹·day⁻¹, exceeding that of commercial cyanobacteria and Synechocystis sp. PCC 6803 cells cultivated under other conditions. The exclusion of HEPES buffer markedly altered the metabolites in the central carbon metabolism; particularly, the levels of compatible solutes, such as sucrose, glucosylglycerol, and glutamate were increased. Although the accumulation of sucrose and glucosylglycerol under high salt conditions is antagonistic to each other, these metabolites accumulated simultaneously in cells grown in the cost-effective medium. Because these metabolites are used in industrial feedstocks, our results reveal the importance of medium composition for the production of metabolites using cyanobacteria.     

A Japanese child with geleophysic dysplasia caused by a novel mutation of FBN1

Geleophysic dysplasia (GD) is a rare disorder characterized by severe short stature, short hands and feet, limited joint mobility, skin thickening, characteristic facial features (e.g., a “happy” face), and cardiac valvular disorders that often result in an early death. The genes ADAMTSL2 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif-like 2) and FBN1 (fibrillin 1) were recently identified as causative genes for GD. Here, we describe a 10-year-old Japanese female with GD who was born to non-consanguineous parents. At the age of 11 months, she was referred to our hospital because of very short stature for her age (− 4.4 standard deviations of the age-matched value) and a “happy” face with full cheeks, a shortened nose, hypertelorism, and a long and flat philtrum, characteristic of GD. Her hands and feet were small, her skin was thickened, and her joint mobility was generally limited. She had cardiac valvular disorders and history of recurrent respiratory failure. Mutation analysis revealed no abnormalities in ADAMTSL2. However, analysis of FBN1 revealed a novel heterozygous mutation (c.5161T > T/G) in exon 41, which encodes transforming growth factor-β-binding protein-like domain 5 (TB5). GD is an extremely rare disorder and, to our knowledge, only one case of GD with an FBN1 mutation has been reported in Japan. Similar to the previously reported cases of GD, the mutation in the current patient was located in the TB5 domain, which suggests that abnormalities in this domain of FBN1 are responsible for GD.     

Distribution of antimicrobial‐resistant lactic acid bacteria in natural cheese in Japan

To determine and compare the extent of contamination caused by antimicrobial‐resistant lactic acid bacteria (LAB) in imported and domestic natural cheeses on the Japanese market, LAB were isolated using deMan, Rogosa and Sharpe (MRS) agar and MRS agar supplemented with six antimicrobials. From 38 imported and 24 Japanese cheeses, 409 LAB isolates were obtained and their antimicrobial resistance was tested. The percentage of LAB resistant to dihydrostreptomycin, erythromycin, and/or oxytetracycline isolated from imported cheeses (42.1%) was significantly higher than that of LAB resistant to dihydrostreptomycin or oxytetracycline from cheeses produced in Japan (16.7%; P = 0.04). Antimicrobial resistance genes were detected in Enterococcus faecalis (tetL, tetM, and ermB; tetL and ermB; tetM) E. faecium (tetM), Lactococcus lactis (tetS), Lactobacillus (Lb.), casei/paracasei (tetM or tetW), and Lb. rhamnosus (ermB) isolated from seven imported cheeses. Moreover, these E. faecalis isolates were able to transfer antimicrobial resistance gene(s). Although antimicrobial resistance genes were not detected in any LAB isolates from Japanese cheeses, Lb. casei/paracasei and Lb. coryniformis isolates from a Japanese farm‐made cheese were resistant to oxytetracycline (minimal inhibitory concentration [MIC], 32 µg/mL). Leuconostoc isolates from three Japanese farm‐made cheeses were also resistant to dihydrostreptomycin (MIC, 32 to > 512 µg/mL). In conclusion, the present study demonstrated contamination with antimicrobial‐resistant LAB in imported and Japanese farm‐made cheeses on the Japanese market, but not in Japanese commercial cheeses.     

Age-related effects of major and trace element concentrations in rat liver and their mutual relationships

The concentrations of 22 major and trace elements in livers from rats aging from 5 to 113 weeks old were determined. The rats investigated were the same rats previously reported with respect to 29 elements in bones (femur) and 26 elements in kidneys. The samples were decomposed with high-purity nitric acid and hydrogen peroxide. Seven elements (Na, Mg, P, K, Ca, Fe and Zn) were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and 15 elements (Mn, Co, Cu, As, Se, Rb, Sr, Mo, Cd, Sn, Sb, Cs, Ba, Pb and Bi) were determined by inductively coupled plasma mass spectrometry (ICP-MS). Analysis of variance (ANOVA) for age variations indicated that the concentrations of many elements, such as Mg, P, K, Mn, Fe, Cu, Zn, Sr, Mo and Cd, were almost constant across the ages of the rats with the exception of 5 weeks old (p > 0.05). Arsenic, Pb and Bi showed significant increasing trends, while Na and Co showed decreasing trends (p < 0.01). Selenium showed a decreasing trend except at the initial stage of 5–9 weeks old. Calcium, Rb, Sn, Sb, Cs and Ba showed significant age-related variations, but their patterns were not monotonic. The liver clearly contrasts with the kidneys, in which many elements showed significant age-related variations with increasing trends. The concentration ranges of Mg, P, K, Mn, Cu, Zn, and Mo were controlled within 15% across all ages of rats. The homeostasis of the aforementioned elements may be well established in the liver. The toxic elements, such as Cd, Pb and Bi, showed a narrow concentration range among age-matched rats.     

Release,Regeneration and Mutant Induction of Pleurotus cornucopiae (‘Tamogitake’) Protoplasts

Both enantiomers of aliphatic and aromatic cyanohydrins were hydrolyzed with the aid of Rhodococcus butanica ATCC 21197 to afford optically active α-hydroxy acids. The usefulness of this reaction is demonstrated by the synthesis of optically pure (R)-4-dodecanolide, a defensive secretion of rove beetles, starting from (R)-2-hydroxydecanenitrile.     

Rapid Purification and Crystallization of Thermostable Malate Dehydrogenase Isolated from a Thermophilic Bacterium,Thermus flavus AT 62

A structural study of the water-soluble dextran made by Leuconostoc mesenteroides strain C (NRRL B-1298) was conducted by enzymic degradation and subsequent ¹³C-NMR analysis of the native dextran and its limit dextrins. The α-l,2-debranching enzyme removed almost all of the branched D-glucose residues, and gave a limit dextrin having a much longer sequence of the internal chain length (degree of linearity: n = 24.5 compared with the value of n = 3.3 for the native dextran). The degree of hydrolysis with debranching enzyme corresponded to the content of α-1,2-linkages determined by chemical methods, which suggested that most of the α-l,2-linkages in the dextran B-1298 constituted branch points of a single D-glucose residue. A synergistic increase of susceptibility of the dextran B-1299 was observed by simultaneous use of debranching enzyme and endodex-tranase. ¹³C-NMR spectral analysis indicated the similarity of structure of dextran B-1298 to that of B-1396, rather than that of B-1299. Occurrence of α-l,3-linkages in the limit dextrin was supported by a newly visualized chemical shift at 83.7 ppm.