Chromosomal Arrangement of Phosphorelay Genes Couples Sporulation and DNA Replication.

Genes encoding proteins in a common regulatory network are frequently located close to one another on the chromosome to facilitate co-regulation or couple gene expression to growth rate. Contrasting with these observations, here, we demonstrate a functional role for the arrangement of Bacillus subtilis sporulation network genes on opposite sides of the chromosome. We show that the arrangement of two sporulation network genes, one located close to the origin and the other close to the terminus, leads to a transient gene dosage imbalance during chromosome replication. This imbalance is detected by the sporulation network to produce cell-cycle coordinated pulses of the sporulation master regulator Spo0A∼P. This pulsed response allows cells to decide between sporulation and continued vegetative growth during each cell cycle spent in starvation. The simplicity of this coordination mechanism suggests that it may be widely applicable in a variety of gene regulatory and stress-response settings. VIDEO ABSTRACT.

The master regulator for entry into sporulation in Bacillus subtilis becomes a mother cell-specific transcription factor for forespore engulfment.

The Spo0A transcription factor is activated by phosphorylation in starving Bacillus subtilis cells. The activated Spo0A (Spo0A~P) regulates genes controlling entry into sporulation and appears to control mother-cell-specific gene expression after asymmetric division, but the latter remains elusive. Here, we found that Spo0A~P directly binds to three conserved DNA sequences (0A1-3) in the promoter region of the mother cell-specific lytic transglycosylase gene spoIID, which is transcribed by σE -RNA polymerase (RNAP) and negatively controlled by the SpoIIID transcription factor and required for forespore engulfment. Systematic mutagenesis of the 0A boxes revealed that the 0A1 and 0A2 boxes located upstream of the promoter positively control the transcription of spoIID. In contrast, the 0A3 box located downstream of the promoter negatively controls the transcription of spoIID. The mutated SpoIIID binding site located between the -35 and -10 promoter elements causes increased expression of spoIID and reduced sporulation. When the mutations of 0A1, 0A2, and IIID sites are combined, sporulation is restored. Collectively, our data suggest that the mother cell-specific spoIID expression is precisely controlled by the coordination of three factors, Spo0A~P, SpoIIID, and σE -RNAP, for proper sporulation. The conservation of this mechanism across spore-forming species was discussed.

Breeding of a Near-Isogenic Wheat Line Resistant to Wheat Blast at Both Seedling and Heading Stages Through Incorporation of Rmg8.

Wheat blast caused by Pyricularia oryzae pathotype Triticum (MoT) has been transmitted from South America to Bangladesh and Zambia and is now spreading in these countries. To prepare against its further spread to Asian countries, we introduced Rmg8, a gene for resistance to wheat blast, into a Japanese elite cultivar, Chikugoizumi (ChI), through recurrent backcrosses and established ChI near-isogenic lines, #2-1-10 with the Rmg8/Rmg8 genotype and #4-2-10 with the rmg8/rmg8 genotype. A molecular analysis suggested that at least 96.6% of the #2-1-10 genome was derived from the recurrent parent ChI. The #2-1-10 line was resistant to MoT not only in primary leaves at the seedling stage but also in spikes and flag leaves at the heading stage. The strength of the resistance in spikes of this Rmg8 carrier was comparable to that of a carrier of the 2NS segment, which has been the only genetic resource released to farmers' fields for wheat blast resistance. On the other hand, the 2NS resistance was not expressed on leaves at the seedling stage nor flag leaves at the heading stage. Considering that leaf blast has been increasingly reported and regarded as an important inoculum source for spike blast, Rmg8 expressed at both the seedling and heading stages, or more strictly in both leaves and spikes, is suggested to be useful to prevent the spread of MoT in Asia and Africa.

Comparison of the empirical linear ablation and low voltage area-guided ablation in addition to pulmonary vein isolation in patients with persistent atrial fibrillation: a propensity score-matched analysis.

BACKGROUND: The efficacy of pulmonary vein isolation (PVI) alone is not guaranteed for persistent atrial fibrillation (PeAF), and it is unclear which type of ablation approach should be applied in addition to PVI. This study aimed to compare outcomes and prognosis between empirical linear ablation and low-voltage area (LVA) ablation after PVI for PeAF. METHODS: We enrolled 128 patients with PeAF who were assigned to the linear ablation group (n = 64) and the LVA ablation group (n = 64) using a propensity score-matched model. After PVI and cardioversion, the patients underwent either empirical linear ablation or LVA ablation during sinus rhythm. All patients in the linear ablation group underwent both roof line and mitral valve isthmus (MVI) ablations. An electrical-guided ablation targeting LVA (< 0.5 mV) was performed in the LVA group. When there was no LVA in the LVA group, only PVI was applied. We compared the procedural outcomes and recurrence after ablation between the two groups. RESULTS: The baseline characteristics were well-balanced between the two groups. Fifty patients had LVA (22 and 28 patients in the linear and LVA groups). The roof and MVI lines were completed in 100% and 96.9% of the patients. During the mean follow-up of 279.5 ± 161.3 days, the LVA group had significantly lower recurrence than the linear group (15 patients [23%] vs. 29 patients [45%], p = 0.014). Thirty-five patients were prescribed antiarrhythmic drugs during the follow-up period (linear group, n = 17; LVA group, n = 18); amiodarone and bepridil were administered to most of the patients (15 and 17 patients, respectively). The difference in the prognosis was relevant among the patients with LVA, while this trend was not observed in those without LVA. The LVA ablation group demonstrated significantly lower radiofrequency energy and shorter procedural time compared to the linear ablation group. The recurrence of atrial flutter was more likely to occur in the linear group than in the LVA group (14 [22%] vs. 6 [9.4%], p = 0.052). CONCLUSION: The electrophysiological-guided LVA ablation is more effective than empirical linear ablation in PeAF patients with LVA. Unnecessary empirical linear ablation might have a risk of iatrogenic gap and atrial flutter recurrence.

Allelic variations of Vrn-1 and Ppd-1 genes in Japanese wheat varieties reveal the genotype-environment interaction for heading time.

The timing of heading is largely affected by environmental conditions. In wheat, Vrn-1 and Ppd-1 have been identified as the major genes involved in vernalization requirement and photoperiod sensitivity, respectively. To compare the effects of Vrn-1 and Ppd-1 alleles on heading time under different environments, we genotyped Vrn-1 and Ppd-1 homoeologues and measured the heading time at Morioka, Tsukuba and Chikugo in Japan for two growing seasons. A total of 128 Japanese and six foreign varieties, classified into four populations based on the 519 genome-wide SNPs, were used for analysis. Varieties with the spring alleles (Vrn-D1a or Vrn-D1b) at the Vrn-D1 locus and insensitive allele (Hapl-I) at the Ppd-D1 locus were found in earlier heading varieties. The effects of Vrn-D1 and Ppd-D1 on heading time were stronger than those of the other Vrn-1 and Ppd-1 homoeologues. Analysis of variance revealed that heading time was significantly affected by the genotype-environment interactions. Some Vrn-1 and Ppd-1 alleles conferred earlier or later heading in specific environments, indicating that the effect of both alleles on the timing of heading depends on the environment. Information on Vrn-1 and Ppd-1 alleles, together with heading time in various environments, provide useful information for wheat breeding.

Genetic mechanisms determining grain number distribution along the spike and their effect on yield components in wheat.

The number of wheat grains is one of the major determinants of yield. Many quantitative trait loci (QTLs) and some causal genes such as GNI-A1 and WAPO-A1 that are associated with grain number per spike (GNS) have been identified, but the underlying mechanisms remain largely unknown. We analyzed QTLs for grain number and other related traits using 188 doubled haploid lines derived from the Japanese high-yield variety, Kitahonami, as a parent to elucidate the genetic mechanism determining grain number. The major QTLs for grain number at the apical, central, and basal parts of the spike were identified in different chromosomal regions. We considered GNI-A1 and WAPO-A1 as candidate genes controlling grain number at the central and basal parts of the spike, respectively. Kitahonami had the favorable 105Y allele of GNI-A1 and WAPO-A1b allele and unfavorable alleles of QTLs for grain number at the apical part of spikes. Pyramiding the favorable alleles of these QTLs significantly increased GNS without significantly reducing thousand-grain weight (TGW). In contrast, the accumulation of favorable alleles of QTLs for TGW significantly decreased GNS, whereas days to heading positively correlated with GNS. Late heading increased the spikelet number per spike, resulting in a higher GNS. Pyramiding of the QTLs for TGW and days to heading also altered the GNS. In conclusion, GNS is a complex trait controlled by many QTLs, and it is essential for breeding to design. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-021-01255-8.

A revised model for the control of fatty acid synthesis by master regulator Spo0A in Bacillus subtilis.

In starving Bacillus subtilis cells, the accDA operon encoding two subunits of the essential acetyl-CoA carboxylase (ACC) has been proposed to be tightly regulated by direct binding of the master regulator Spo0A to a cis element (0A box) in the promoter region. When the 0A box is mutated, biofilm formation and sporulation have been reported to be impaired. Here, we present evidence that two 0A boxes, one previously known (0A-1) and another newly discovered (0A-2) in the accDA promoter region are positively and negatively regulated by Spo0A∼P respectively. Cells with mutated 0A boxes experience slight delays in sporulation, but eventually sporulate with high efficiency. In contrast, cells harboring a single mutated 0A-2 box are deficient for biofilm formation, while cells harboring either a mutated 0A-1 box or both mutated 0A boxes form biofilms. We further show that the essential ACC enzyme localizes on or near the cell membrane by directly observing a functional GFP fusion to one of the enzyme's subunits. Collectively, we propose a revised model in which accDA is primarily transcribed by a major σA -RNA polymerase, while Spo0A∼P plays an additional role in the fine-tuning of accDA expression upon starvation to support proper biofilm formation and sporulation.

DdvK, a Novel Major Facilitator Superfamily Transporter Essential for 5,5'-Dehydrodivanillate Uptake by Sphingobium sp. Strain SYK-6.

The microbial conversion of lignin-derived aromatics is a promising strategy for the industrial utilization of this large biomass resource. However, efficient application requires an elucidation of the relevant transport and catabolic pathways. In Sphingobium sp. strain SYK-6, most of the enzyme genes involved in 5,5'-dehydrodivanillate (DDVA) catabolism have been characterized, but the transporter has not yet been identified. Here, we identified SLG_07710 (ddvK) and SLG_07780 (ddvR), genes encoding a putative major facilitator superfamily (MFS) transporter and MarR-type transcriptional regulator, respectively. A ddvK mutant of SYK-6 completely lost the capacity to grow on and convert DDVA. DdvR repressed the expression of the DDVA O-demethylase oxygenase component gene (ligXa), while DDVA acted as the gene inducer. A DDVA uptake assay was developed by employing this DdvR-controlled ligXa transcriptional regulatory system. A Sphingobium japonicum UT26S transformant expressing ddvK acquired DDVA uptake capacity, indicating that ddvK encodes the DDVA transporter. DdvK, probably requiring the proton motive force, was suggested to be a novel MFS transporter on the basis of the amino acid sequence similarity. Subsequently, we evaluated the effects of ddvK overexpression on the production of the DDVA metabolite 2-pyrone-4,6-dicarboxylate (PDC), a building block of functional polymers. A SYK-6 mutant of the PDC hydrolase gene (ligI) cultured in DDVA accumulated PDC via 5-carboxyvanillate and grew by utilizing 4-carboxy-2-hydroxypenta-2,4-dienoate. The introduction of a ddvK-expression plasmid into a ligI mutant increased the growth rate in DDVA and the amounts of DDVA converted and PDC produced after 48 h by 1.35- and 1.34-fold, respectively. These results indicate that enhanced transporter gene expression can improve metabolite production from lignin derivatives.IMPORTANCE The bioengineering of bacteria to selectively transport and metabolize natural substrates into specific metabolites is a valuable strategy for industrial-scale chemical production. The uptake of many substrates into cells requires specific transport systems, and so the identification and characterization of transporter genes are essential for industrial applications. A number of bacterial major facilitator superfamily transporters of aromatic acids have been identified and characterized, but many transporters of lignin-derived aromatic acids remain unidentified. The efficient conversion of lignin, an abundant but unutilized aromatic biomass resource, to value-added metabolites using microbial catabolism requires the characterization of transporters for lignin-derived aromatics. In this study, we identified the transporter gene responsible for the uptake of 5,5'-dehydrodivanillate, a lignin-derived biphenyl compound, in Sphingobium sp. strain SYK-6. In addition to characterizing its function, we applied this transporter gene to the production of a value-added metabolite from 5,5'-dehydrodivanillate.

Slowdown of growth controls cellular differentiation.

How can changes in growth rate affect the regulatory networks behavior and the outcomes of cellular differentiation? We address this question by focusing on starvation response in sporulating Bacillus subtilis We show that the activity of sporulation master regulator Spo0A increases with decreasing cellular growth rate. Using a mathematical model of the phosphorelay-the network controlling Spo0A-we predict that this increase in Spo0A activity can be explained by the phosphorelay protein accumulation and lengthening of the period between chromosomal replication events caused by growth slowdown. As a result, only cells growing slower than a certain rate reach threshold Spo0A activity necessary for sporulation. This growth threshold model accurately predicts cell fates and explains the distribution of sporulation deferral times. We confirm our predictions experimentally and show that the concentration rather than activity of phosphorelay proteins is affected by the growth slowdown. We conclude that sensing the growth rates enables cells to indirectly detect starvation without the need for evaluating specific stress signals.

Transcriptional Profile during Deoxycholate-Induced Sporulation in a Clostridium perfringens Isolate Causing Foodborne Illness.

UNLABELLED: Clostridium perfringens type A is a common source of foodborne illness (FBI) in humans. Vegetative cells sporulate in the small intestinal tract and produce the major pathogenic factor C. perfringens enterotoxin. Although sporulation plays a critical role in the pathogenesis of FBI, the mechanisms inducing sporulation remain unclear. Bile salts were shown previously to induce sporulation, and we confirmed deoxycholate (DCA)-induced sporulation in C. perfringens strain NCTC8239 cocultured with human intestinal epithelial Caco-2 cells. In the present study, we performed transcriptome analyses of strain NCTC8239 in order to elucidate the mechanism underlying DCA-induced sporulation. Of the 2,761 genes analyzed, 333 were up- or downregulated during DCA-induced sporulation and included genes for cell division, nutrient metabolism, signal transduction, and defense mechanisms. In contrast, the virulence-associated transcriptional regulators (the VirR/VirS system, the agr system, codY, and abrB) were not activated by DCA. DCA markedly increased the expression of signaling molecules controlled by Spo0A, the master regulator of the sporulation process, whereas the expression of spo0A itself was not altered in the presence or absence of DCA. The phosphorylation of Spo0A was enhanced in the presence of DCA. Collectively, these results demonstrated that DCA induced sporulation, at least partially, by facilitating the phosphorylation of Spo0A and activating Spo0A-regulated genes in strain NCTC8239 while altering the expression of various genes. IMPORTANCE: Disease caused by Clostridium perfringens type A consistently ranks among the most common bacterial foodborne illnesses in humans in developed countries. The sporulation of C. perfringens in the small intestinal tract is a key event for its pathogenesis, but the factors and underlying mechanisms by which C. perfringens sporulates in vivo currently remain unclear. Bile salts, major components of bile, which is secreted from the liver for the emulsification of lipids, were shown to induce sporulation. However, the mechanisms underlying bile salt-induced sporulation have not yet been clarified. In the present study, we demonstrate that deoxycholate (one of the bile salts) induces sporulation by facilitating the phosphorylation of Spo0A and activating Spo0A-regulated genes using a transcriptome analysis. Thus, this study enhances our understanding of the mechanisms underlying sporulation, particularly that of bile salt-induced sporulation, in C. perfringens.

Evidence that Autophosphorylation of the Major Sporulation Kinase in Bacillus subtilis Is Able To Occur in trans.

UNLABELLED: Entry into sporulation in Bacillus subtilis is governed by a multicomponent phosphorelay, a complex version of a two-component system which includes at least three histidine kinases (KinA to KinC), two phosphotransferases (Spo0F and Spo0B), and a response regulator (Spo0A). Among the three histidine kinases, KinA is known as the major sporulation kinase; it is autophosphorylated with ATP upon starvation and then transfers a phosphoryl group to the downstream components in a His-Asp-His-Asp signaling pathway. Our recent study demonstrated that KinA forms a homotetramer, not a dimer, mediated by the N-terminal domain, as a functional unit. Furthermore, when the N-terminal domain was overexpressed in the starving wild-type strain, sporulation was impaired. We hypothesized that this impairment of sporulation could be explained by the formation of a nonfunctional heterotetramer of KinA, resulting in the reduced level of phosphorylated Spo0A (Spo0A∼P), and thus, autophosphorylation of KinA could occur in trans. To test this hypothesis, we generated a series of B. subtilis strains expressing homo- or heterogeneous KinA protein complexes consisting of various combinations of the phosphoryl-accepting histidine point mutant protein and the catalytic ATP-binding domain point mutant protein. We found that the ATP-binding-deficient protein was phosphorylated when the phosphorylation-deficient protein was present in a 1:1 stoichiometry in the tetramer complex, while each of the mutant homocomplexes was not phosphorylated. These results suggest that ATP initially binds to one protomer within the tetramer complex and then the γ-phosphoryl group is transmitted to another in a trans fashion. We further found that the sporulation defect of each of the mutant proteins is complemented when the proteins are coexpressed in vivo. Taken together, these in vitro and in vivo results reinforce the evidence that KinA autophosphorylation is able to occur in a trans fashion. IMPORTANCE: Autophosphorylation of histidine kinases is known to occur by either the cis (one subunit of kinase phosphorylating itself within the multimer) or the trans (one subunit of the multimer phosphorylates the other subunit) mechanism. The present study provided direct in vivo and in vitro evidence that autophosphorylation of the major sporulation histidine kinase (KinA) is able to occur in trans within the homotetramer complex. While the physiological and mechanistic significance of the trans autophosphorylation reaction remains obscure, understanding the detailed reaction mechanism of the sporulation kinase is the first step toward gaining insight into the molecular mechanisms of the initiation of sporulation, which is believed to be triggered by unknown factors produced under conditions of nutrient depletion.

In vivo functional characterization of the transmembrane histidine kinase KinC in Bacillus subtilis.

In response to starvation, Bacillus subtilis cells differentiate into different subsets, undergoing cannibalism, biofilm formation or sporulation. These processes require a multiple component phosphorelay, wherein the master regulator Spo0A is activated upon phosphorylation by one or a combination of five histidine kinases (KinA-KinE) via two intermediate phosphotransferases, Spo0F and Spo0B. In this study, we focused on KinC, which was originally identified as a sporulation kinase and was later shown to regulate cannibalism and biofilm formation. First, genetic experiments using both the domesticated and undomesticated (biofilm forming) strains revealed that KinC activity and the membrane localization are independent of both the lipid raft marker proteins FloTA and cytoplasmic potassium concentration, which were previously shown to be required for the kinase activity. Next, we demonstrated that KinC controls cannibalism and biofilm formation in a manner dependent on phosphorelay. For further detailed characterization of KinC, we established an IPTG-inducible expression system in the domesticated strain, in which biofilm formation is defective, for simplicity of study. Using this system, we found that the N-terminal transmembrane domain is dispensable but the PAS domain is needed for the kinase activity. An in vivo chemical cross-linking experiment demonstrated that the soluble and functional KinC (KinC(ΔTM1+2)) forms a tetramer. Based on these results, we propose a revised model in which KinC becomes active by forming a homotetramer via the N-terminal PAS domain, but its activity is independent of both the lipid raft and the potassium leakage, which was previously suggested to be induced by surfactin.

Efficacy and safety of apixaban in the patients undergoing the ablation of atrial fibrillation.

INTRODUCTION: Apixaban, a factor Xa (FXa) inhibitor, is a new oral anticoagulant for stroke prevention in atrial fibrillation (AF). However, little is known about its efficacy and safety as a periprocedural anticoagulant therapy for patients who had undergone catheter ablation (CA) for AF. METHODS AND RESULTS: We evaluated 342 consecutive patients who underwent CA for AF between April 2013 and March 2014 and received apixaban (n = 105) and warfarin (n = 237) for uninterrupted periprocedural anticoagulation. We retrospectively investigated the occurrence of bleeding and thromboembolic complications during the procedural period and compared them between the apixaban group (AG) and warfarin group (WG). Thromboembolic complications occurred in one (0.4%) patient in the WG. Major and minor bleeding complications occurred in one (1%) and four (4%) patients in the AG, and three (1%) and 12 (5%) patients in the WG. No significant difference in complications was observed between the AG and WG. Of importance, adverse event rates did not differ between the two groups after adjusting by a propensity score analysis. In preoperative tests of blood coagulation, there were significant differences in the prothrombin time, activated partial thromboplastin time, FXa activity, and prothrombin fragment 1 + 2 (F1+2) levels between the AG and WG. CONCLUSION: The use of apixaban during the periprocedural period of AF ablation seemed as efficacious and safe as warfarin.

Ultrasensitivity of the Bacillus subtilis sporulation decision.

Starving Bacillus subtilis cells execute a gene expression program resulting in the formation of stress-resistant spores. Sporulation master regulator, Spo0A, is activated by a phosphorelay and controls the expression of a multitude of genes, including the forespore-specific sigma factor σ(F) and the mother cell-specific sigma factor σ(E). Identification of the system-level mechanism of the sporulation decision is hindered by a lack of direct control over Spo0A activity. This limitation can be overcome by using a synthetic system in which Spo0A activation is controlled by inducing expression of phosphorelay kinase KinA. This induction results in a switch-like increase in the number of sporulating cells at a threshold of KinA. Using a combination of mathematical modeling and single-cell microscopy, we investigate the origin and physiological significance of this ultrasensitive threshold. The results indicate that the phosphorelay is unable to achieve a sufficiently fast and ultrasensitive response via its positive feedback architecture, suggesting that the sporulation decision is made downstream. In contrast, activation of σ(F) in the forespore and of σ(E) in the mother cell compartments occurs via a cascade of coherent feed-forward loops, and thereby can produce fast and ultrasensitive responses as a result of KinA induction. Unlike σ(F) activation, σ(E) activation in the mother cell compartment only occurs above the KinA threshold, resulting in completion of sporulation. Thus, ultrasensitive σ(E) activation explains the KinA threshold for sporulation induction. We therefore infer that under uncertain conditions, cells initiate sporulation but postpone making the sporulation decision to average stochastic fluctuations and to achieve a robust population response.

Molecular and genealogical analysis of grain dormancy in Japanese wheat varieties, with specific focus on MOTHER OF FT AND TFL1 on chromosome 3A.

In the wheat (Triticum aestivum L.) cultivar 'Zenkoujikomugi', a single nucleotide polymorphism (SNP) in the promoter of MOTHER OF FT AND TFL1 on chromosome 3A (MFT-3A) causes an increase in the level of gene expression, resulting in strong grain dormancy. We used a DNA marker to detect the 'Zenkoujikomugi'-type (Zen-type) SNP and examined the genotype of MFT-3A in Japanese wheat varieties, and we found that 169 of 324 varieties carry the Zen-type SNP. In Japanese commercial varieties, the frequency of the Zen-type SNP was remarkably high in the southern part of Japan, but low in the northern part. To examine the relationship between MFT-3A genotype and grain dormancy, we performed a germination assay in three wheat-growing seasons. On average, the varieties carrying the Zen-type SNP showed stronger grain dormancy than the varieties carrying the non-Zen-type SNP. Among commercial cultivars, 'Iwainodaichi' (Kyushu), 'Junreikomugi' (Kinki-Chugoku-Shikoku), 'Kinuhime' (Kanto-Tokai), 'Nebarigoshi' (Tohoku-Hokuriku), and 'Kitamoe' (Hokkaido) showed the strongest grain dormancy in each geographical group, and all these varieties, except for 'Kitamoe', were found to carry the Zen-type SNP. In recent years, the number of varieties carrying the Zen-type SNP has increased in the Tohoku-Hokuriku region, but not in the Hokkaido region.

Triggering sporulation in Bacillus subtilis with artificial two-component systems reveals the importance of proper Spo0A activation dynamics.

Sporulation initiation in Bacillus subtilis is controlled by the phosphorylated form of the master regulator Spo0A which controls transcription of a multitude of sporulation genes. In this study, we investigated the importance of temporal dynamics of phosphorylated Spo0A (Spo0A∼P) accumulation by rewiring the network controlling its phosphorylation. We showed that simultaneous induction of KinC, a kinase that can directly phosphorylate Spo0A, and Spo0A itself from separately controlled inducible promoters can efficiently trigger sporulation even under nutrient rich conditions. However, the sporulation efficiency in this artificial two-component system was significantly impaired when KinC and/or Spo0A induction was too high. Using mathematical modelling, we showed that gradual accumulation of Spo0A∼P is essential for the proper temporal order of the Spo0A regulon expression, and that reduction in sporulation efficiency results from the reversal of that order. These insights led us to identify premature repression of DivIVA as one possible explanation for the adverse effects of accelerated accumulation of Spo0A∼P on sporulation. Moreover, we found that positive feedback resulting from autoregulation of the native spo0A promoter leads to robust control of Spo0A∼P accumulation kinetics. Thus we propose that a major function of the conserved architecture of the sporulation network is controlling Spo0A activation dynamics.

Clinical outcome of implantable cardioverter defibrillators with recalled and non-recalled leads in Japanese patients. Increased failure rate of the Sprint Fidelis lead.

BACKGROUND: In recent years, there has been a series of recalls of popular implantable cardioverter defibrillators leads, and several reports have demonstrated an increasing rate of failure of such leads over time in Caucasian patients. However, little is known about the performance of these leads in Asian patients. The aim of this study was to investigate the rate of failure of the recalled leads and the characteristics as compared with non-recalled leads in Japanese patients. METHODS AND RESULTS: A retrospective chart review was conducted in 214 patients (75 Sprint Fidelis, 8 Riata, and 131 Sprint Quattro leads) who underwent implantation and follow-up at Nagoya University Hospital. During the follow-up period, 14 Sprint Fidelis leads (19%) and 1 Riata lead (13%) failed, but no abnormality was found in the Sprint Quattro, non-recalled leads. Five patients (4 Sprint Fidelis and 1 Riata, 33% of lead failure patients) received inappropriate shocks. The 3-, 4-, and 5-year lead survival rates in Sprint Fidelis leads were 95.1% (95% confidence interval [CI]: 89.6%-100%), 89.8% (95% CI: 82.1%-97.6%), and 88.0% (95% CI: 79.6%-96.4%), respectively. A previous device implantation before Sprint Fidelis lead was the only significant predictor for lead fracture (hazard ratio, 5.33; 95% CI: 1.55-18.4; P=0.008). CONCLUSIONS: The rate of Sprint Fidelis lead failure continues to increase over time in Japanese patients.

Clinical characteristics and predictors of super-response to cardiac resynchronization therapy: a combination of predictive factors.

BACKGROUND: Patients with greater improvement of cardiac function after cardiac resynchronization therapy (CRT) implantation are identified as "super-responders." However, it remains unclear which kind of preimplant assessments could accurately predict outcomes after CRT. Thus, we aimed to examine the essential predicting factors for super-response to CRT, and to construct an accurate predictable model. METHODS: We retrospectively analyzed the CRT patients who underwent implantation at Nagoya University Hospital. Super-responders are defined as those who show a relative reduction in left ventricular end-systolic volume ≥30% after 6 months of CRT. RESULTS: Eighty patients (mean age, 67.8 ± 10.2 years) were included. Twenty-two patients received upgrading procedure to CRT implantation. Six months after the implantation, 29 patients (36%) were super-responders. Multiple logistic regression analysis shows that consistent right ventricular pacing with a previous device (odds ratio [OR] 7.28, 95% confidence interval [CI] 1.52-34.9; P = 0.013), lack of prior history of ventricular arrhythmia (OR 5.32, 95% CI 1.52-18.6; P = 0.009), and smaller left atrial diameter (LAD) (OR 0.92, 95% CI 0.86-0.98; P = 0.014) are independent predictors for CRT super-responders. The use of a combination of these predictive factors could increase the certainty with which a greater response to CRT is predicted and the presence of such a combination could improve prognosis. CONCLUSION: Greater response to biventricular pacing occurs more frequently in patients with consistent right ventricular pacing, lack of prior history of ventricular arrhythmia, and smaller LAD. An association between patient background characteristics and a super-response to CRT was also identified.

Regulation of Seed Dormancy Genes in Triticeae Species.

Wild progenitors of Triticeae crops generally have long dormancy periods. Domesticated crops inherited these longer dormancy alleles from their wild progenitors, which have since been modified and selected during cultivation and utilization by humans. Thus, allelic combinations at different seed dormancy loci are currently represented in Triticeae germplasm preserved in seed repositories and gene banks as accessions and materials of breeding programs. Methods to evaluate seed dormancy are key to explore, analyze, and exploit optimal alleles in dormancy genes. Recent developments in genomics have accelerated the identification and analysis of seed dormancy loci in Triticeae species. Transgenic experiments have been conducted to validate if candidate genes affect seed dormancy and more recently have yielded an array of mutations derived from genome editing for practical applications. The information gathered on these seed dormancy loci provides a deeper knowledge of germplasm diversity and offers strategies to control seed dormancy in breeding programs in Triticeae crops.

Evaluation Methods for Preharvest Sprouting Resistance in Japanese Wheat Breeding Programs.

Different methodologies have been applied for the selection of preharvest sprouting resistance in cereal breeding programs. We describe here a series of methods used in practical wheat breeding programs in Japan, including phenotyping based on germination score after artificial rain treatments and genotyping using DNA markers. These methods can be modified and applied to breeding programs in which preharvest sprouting is a problem during cereal cultivation.