Supramolecular Senolytics via Intracellular Oligomerization of Peptides in Response to Elevated Reactive Oxygen Species Levels in Aging Cells.

Senolytics, which eliminate senescent cells from tissues, represent an emerging therapeutic strategy for various age-related diseases. Most senolytics target antiapoptotic proteins, which are overexpressed in senescent cells, limiting specificity and inducing severe side effects. To overcome these limitations, we constructed self-assembling senolytics targeting senescent cells with an intracellular oligomerization system. Intracellular aryl-dithiol-containing peptide oligomerization occurred only inside the mitochondria of senescent cells due to selective localization of the peptides by RGD-mediated cellular uptake into integrin αvß3-overexpressed senescent cells and elevated levels of reactive oxygen species, which can be used as a chemical fuel for disulfide formation. This oligomerization results in an artificial protein-like nanoassembly with a stable α-helix secondary structure, which can disrupt the mitochondrial membrane via multivalent interactions because the mitochondrial membrane of senescent cells has weaker integrity than that of normal cells. These three specificities (integrin αvß3, high ROS, and weak mitochondrial membrane integrity) of senescent cells work in combination; therefore, this intramitochondrial oligomerization system can selectively induce apoptosis of senescent cells without side effects on normal cells. Significant reductions in key senescence markers and amelioration of retinal degeneration were observed after elimination of the senescent retinal pigment epithelium by this peptide senolytic in an age-related macular degeneration mouse model and in aged mice, and this effect was accompanied by improved visual function. This system provides a strategy for the treatment of age-related diseases using supramolecular senolytics.

Perspectives on the Doctor of Public Health (DrPH) education among students and alumni in the United States: a cross-sectional national online survey.

BACKGROUND: This study explored the current and desired identity of the DrPH degree, focusing on whether the competencies set by the Council on Education for Public Health (CEPH) adequately prepare DrPH graduates for effective public health practice. Additionally, the study investigated the necessity of standardization in DrPH training, referring to a consensus-driven approach that equips future public health practitioners with practical skillsets applicable in real-world scenarios. METHODS: A national cross-sectional online survey titled "National DrPH leaders & practitioners needs assessment" was conducted from November 2020 to February 2021. The survey was based on a self-report by DrPH students and DrPH professionals, consisting of the following two main components: (1) how their DrPH training aligns with CEPH competencies and (2) how they perceive the identity of the DrPH degree. Convenience sampling was used to collect the data, which may have limited representation for all DrPH institutions in the United States. RESULTS: A total of 222 participants (140 current DrPH students and 82 alumni) completed the survey. The mean of the 10-point Likert scale for the degree to which the DrPH training aligns with 26 CEPH competencies (1: not at all - 10: absolutely) ranged from 6.3 (SD: 2.78) to 7.96 (SD: 2.16). The majority of participants (191/222, 86.04%) were satisfied with the knowledge and skills reflected in their training based on the CEPH competencies. However, more than half of the participants (117/222, 52.70%) sought additional professional development/training outside their institutions. DrPH leaders and practitioners faced barriers where the value of their work might not be fully recognized and endorsed. Participants indicated that the DrPH education should be further distinguished from the PhD education. CONCLUSIONS: The DrPH degree holds significant value within the academic sphere of public health practice in the United States. However, its distinction from PhD programs poses a challenge for employers and organizations in the field, requiring attention from higher education programs. By solidifying the DrPH's identity, graduates can effectively address diverse public health issues and contribute to creating a safe and healthy environment, including addressing the challenges posed by the COVID-19 pandemic.

Analysis of the Doctor of Public Health (DrPH) training and identity needs in the United States: a qualitative study.

BACKGROUND: The Doctor of Public Health (DrPH) is the highest attainable degree in the field of public health, specifically designed to prepare professionals to address complex public health challenges in practical settings. This study was designed to explore the importance of achieving a shared and uniform understanding of DrPH education, assess the optimal direction for DrPH training, and investigate the specific curriculum requirements by gathering insights from current DrPH students and alumni in the United States. METHODS: A total of 13 focus group discussions and two in-depth interviews (total participants: 50) were conducted through Zoom to see how DrPH students and alumni assessed their DrPH educational programs. RESULTS: Three overarching findings emerged from the analysis of focus group discussions and in-depth interviews. First, participants expressed a preference against a national DrPH board examination, but advocated for a standardized common core curriculum that extends across the entire nation. Second, the ideal direction for DrPH training was perceived to involve a practice-based approach, emphasizing the importance of multi-, inter-, and trans-disciplinary instruction delivered by faculty with practical experience. Last, there was a demand for a DrPH-specific unique curriculum encompassing areas such as mixed method analysis, leadership and management, applied communication, crisis and change management, proficiency in addressing contemporary topics, and tailored applied and integrative learning requirements specific to the DrPH program. CONCLUSIONS: We explored a range of DrPH training and identity needs among 50 participants, comprised of students and alumni who directly benefit from DrPH education. By considering these inputs, individuals from institutions that offer the DrPH degree can further enhance the quality of public health practice training and make significant contributions to the overall advancement of the field of public health.

The Design of GNSS/IMU Loosely-Coupled Integration Filter for Wearable EPTS of Football Players.

This study presents the filter design of GNSS/IMU integration for wearable EPTS (Electronic Performance and Tracking System) of football players. EPTS has been widely used in sports fields recently, and GNSS (Global Navigation Satellite System) and IMU (Inertial Measurement Unit) in wearable EPTS have been used to measure and provide players' athletic performance data. A sensor fusion technique can be used to provide high-quality analysis data of athletic performance. For this reason, the integration filter of GNSS data and IMU data is designed in this study. The loosely-coupled strategy is considered to integrate GNSS and IMU data considering the specification of the wearable EPTS product. Quaternion is used to estimate a player's attitude to avoid the gimbal lock singularity in this study. Experiment results validate the performance of the proposed GNSS/IMU loosely-coupled integration filter for wearable EPTS of football players.

Accelerated aging phenotypes in the retinal pigment epithelium of Zmpste24-deficient mice.

Age-related macular degeneration (AMD) is a chronic and progressive disease characterized by degeneration of the retinal pigment epithelium (RPE) and retina that ultimately leads to loss of vision. The pathological mechanisms of AMD are not fully known. Cellular senescence, which is a state of cell cycle arrest induced by DNA-damage or aging, is hypothesized to critically affect the pathogenesis of AMD. In this study, we examined the relationship between cellular senescence and RPE/retinal degeneration in mouse models of natural aging and accelerated aging. We performed a bulk RNA sequencing of the RPE cells from adult (8 months old) and naturally-aged old (24 months old) mice and found that common signatures of senescence and AMD pathology - inflammation, apoptosis, and blood vessel formation - are upregulated in the RPE of old mice. Next, we investigated markers of senescence and the degree of RPE/retinal degeneration in Zmpste24-deficient (Zmpste24-/-) mice, which is a model for progeria and accelerated aging. We found that Zmpste24-/- mice display markedly greater level of senescence-related markers in RPE and significant RPE/retinal degeneration compared to wild-type mice, in a manner consistent with natural aging. Overall, these results provide support for the association between cellular senescence of RPE and the pathogenesis of AMD, and suggest the use of Zmpste24-/- mice as a novel senescent RPE model of AMD.

The impact of changing nonimmigrant visa policies on international students' psychological adjustment and well-being in the United States during the COVID-19 pandemic: a qualitative study.

BACKGROUND: Since the Immigration and Nationality Act of 1952, the number of international students in the United States had been gradually increasing. However, the total numbers have begun to decrease since 2019-2020 school year due to the Trump administration's policy and COVID-19. Still, little is known about how international students' psychological adjustment and well-being have been affected by changing nonimmigrant visa policy and the COVID-19 pandemic.  METHODS: We conducted a total of 34 online semi-structured in-depth interviews with international students from 18 countries of origin studying in the San Francisco Bay Area, California. More than 60% of the participants (21 out of 34) were aged 21 to 25. Among our 34 participants, gender and 18 were male and 16 were female, and 19 were undergraduate students and 15 were master's students. The majority of the participants were first-generation college students (22/34, 64.71%). Verbatim transcription was done for all interviews. NVivo was used for both deductive and inductive approaches to the qualitative analysis. RESULTS: Overall, the recent political climate negatively impacted participants' psychology of adjustment and well-being. July 6, 2020 Policy Directive for international students caused severe uncertainty about whether they can continue studying in the United States. There were many resources or services needed to overcome this period, such as extended mental and emotional support from the counseling services as well as financial and informational support from the international student office and university. Although international students had the benefit of the university's food assistance program, they were not eligible to receive any external support outside of the university and financial aid at the local and federal levels. Whether maintaining F-1 visa status was one of their major concerns. Due to COVID-19, job opportunities were limited, which made international students difficult to obtain Curricular Practical Training (CPT) and secure a job in the United States within the 90-day unemployment limit of Optical Practical Training (OPT). H-1B visa and permanent residency were other challenges to go through, but participants saw positive perspectives from the Biden administration. CONCLUSIONS: Uncertain policy changes due to COVID-19 and presidential transitions impacted international students' psychological well-being and adjustment. International students are important populations in the United States who have supported jobs that are high in demand and economically contributed to the United States. It is expected that future policies at various levels support international students' life and improve their health equity and mental health.

Future directions of Doctor of Public Health education in the United States: a qualitative study.

BACKGROUND: The Doctor of Public Health (DrPH) degree is an advanced and terminal professional degree that prepares the future workforce to engage in public health research, teaching, practice, and leadership. The purpose of the present research was to discuss the desirable future direction and optimal education strategies for the DrPH degree in the United States. METHODS: A total of 28 Council on Education for Public Health (CEPH)-accredited DrPH programs in the United States was identified through the Association of Schools and Programs of Public Health (ASPPH) Academic Program Finder. Then, a qualitative analysis was conducted to obtain perspectives from a total of 20 DrPH program directors through in-depth interviews. RESULTS: A DrPH program should be recognized as equal but different from an MPH or a PhD program and strengthen the curriculum of methodology and leadership education. It is important that a DrPH program establishes specific partnerships with other entities and provide funding for students. In addition, rather than being standardized nationwide, there is value in each DrPH program maintaining its unique character and enabling students to be open to all career pathways. CONCLUSIONS: The future of DrPH programs in the twenty-first century should aim at effective interdisciplinary public health approaches that draw from the best of both academic and applied sectors. A DrPH program is expected to provide academic, applied public health, and leadership training for students to pursue careers in either academia or the public/private sector, because public health is an applied social science that bridges the gap between research and practice.

Disruption of the polyubiquitin gene Ubb reduces the self-renewal capacity of neural stem cells.

Ubiquitin (Ub) is a highly conserved eukaryotic protein that plays pivotal roles in cellular signal transduction, differentiation, and proteolysis. Although we have previously reported that disruption of the polyubiquitin gene Ubb is associated with the dysregulated differentiation of neural stem cells (NSCs) into neurons, it is unclear how gene expression patterns are altered in Ubb knockout (KO) NSCs, and whether this altered gene expression contributes to Ubb KO neural phenotypes. To answer these questions, we used RNA-Seq to compare the transcriptomes of Ubb KO NSCs and Ubb heterozygous (HT) controls. We found that the expression levels of most proliferation markers were decreased in Ubb KO NSCs. To determine whether the reduced levels of proliferation markers were due to reduced self-renewal of NSCs, such as radial glia, we measured the levels of the radial glia marker, Pax6, in mouse embryonic brains at 14.5 dpc. We found that Pax6 levels were decreased and the ventricular zone was thinner in the embryonic brains of Ubb KO mice compared to those of wild-type (WT) control mice. To determine whether the decreased self-renewal of Ubb KO NSCs was caused by cell-autonomous defects and not due to their microenvironment, we transplanted NSCs into WT mouse brains using a cannula system. In mouse brain sections, immunoreactivity of the NSC marker, nestin, was much lower in Ubb KO NSCs than in Ubb HT controls. Therefore, our data suggest that cell-autonomous defects, due to the disruption of Ubb, lead to a decrease in the self-renewal capacity of NSCs and may contribute to their dysregulated differentiation into neurons.

Protective Role of Bacterial Alkanesulfonate Monooxygenase under Oxidative Stress.

Bacterial alkane metabolism is associated with a number of cellular stresses, including membrane stress and oxidative stress, and the limited uptake of charged ions such as sulfate. In the present study, the genes ssuD and tauD in Acinetobacter oleivorans DR1 cells, which encode an alkanesulfonate monooxygenase and a taurine dioxygenase, respectively, were found to be responsible for hexadecanesulfonate (C16SO3H) and taurine metabolism, and Cbl was experimentally identified as a potential regulator of ssuD and tauD expression. The expression of ssuD and tauD occurred under sulfate-limited conditions generated during n-hexadecane degradation. Interestingly, expression analysis and knockout experiments suggested that both genes are required to protect cells against oxidative stress, including that generated by n-hexadecane degradation and H2O2 exposure. Measurable levels of intracellular hexadecanesulfonate were also produced during n-hexadecane degradation. Phylogenetic analysis suggested that ssuD and tauD are mainly present in soil-dwelling aerobes within the Betaproteobacteria and Gammaproteobacteria classes, which suggests that they function as controllers of the sulfur cycle and play a protective role against oxidative stress in sulfur-limited conditions.IMPORTANCEssuD and tauD, which play a role in the degradation of organosulfonate, were expressed during n-hexadecane metabolism and oxidative stress conditions in A. oleivorans DR1. Our study confirmed that hexadecanesulfonate was accidentally generated during bacterial n-hexadecane degradation in sulfate-limited conditions. Removal of this by-product by SsuD and TauD must be necessary for bacterial survival under oxidative stress generated during n-hexadecane degradation.

Sphingomonas changnyeongensis sp. nov. isolated from the Hapcheon-Changnyeong barrage area in the Nakdong river.

The novel bacterial strain C33T was isolated from a freshwater sample collected from the Hapcheon-Changnyeong barrage. The Gram-negative, motile, yellow-pigmented strain C33T was characterized as a rod-shaped and strictly aerobic bacterium. A 16S-rRNA phylogenetic analysis revealed that this strain was most closely related to Sphingomonas changbaiensis V2M44T, Sphingomonas tabacisoli X1-8T, and Sphingomonas flavalba ZLT-5T with 97.1, 97.0, and 95.0 % 16S-rRNA sequence similarities, respectively. The genomic DNA GC content of strain C33T was estimated at 65.0 mol%. The average nucleotide identity of strain C33T relative to S. changbaiensis V2M44T and S. flavalba ZLT-5T was found to be 77.0 and 75.6%, with average amino-acid identities of 69.9, and 66.7%, and the digital DNA-DNA hybridization values of 21.3 and 17.7 %, respectively. The cells grew at 19-37 °C and pH 6-9 with 0-0.5 % (w/v) NaCl (optimum: 28 °C, pH 6.5, and 0 % NaCl). The major component identified in the polyamine pattern was sym-homospermidine, and the main ubiquinone was Q-10. The predominant polar lipids characterized were diphophatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine, and sphingoglycolipid. Iso-C15 : 0, C15 : 0 anteiso, and summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) were found to be the primary cellular fatty acids in strain C33T. Based on these genotypic and phenotypic characteristics, strain C33T was classified as a novel species of the genus Sphingomonas; and the name Sphingomonas changnyeongensis sp. nov. is proposed (=KACC 21511T=JCM 33880T).

Bacillus miscanthi sp. nov., a alkaliphilic bacterium from the rhizosphere of Miscanthus sacchariflorus.

A novel bacterial strain, designated AK13T (=KACC 21401T=DSM 109981T), was isolated from the rhizosphere of Miscanthus sacchariflorus. Strain AK13T was found to be an aerobic, Gram-stain-positive, endospore-forming and rod-shaped bacterium. It formed yellow circular colonies with smooth convex surfaces. The genomic DNA G+C content of strain AK13T was estimated to be 40 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that this strain was most closely related to Bacillus lehensis MLB2T (99.4 %), Bacillus oshimensis K11T (98.8 %) and Bacillus patagoniensis PAT 05T (96.6 %). The average nucleotide identity values between strain AK13T and B. lehensis MLB2T, B. oshimensis K11T and B. patagoniensis PAT 05T were 90.93, 91.05 and 71.87 %, respectively, with the digital DNA-DNA hybridization values of 42.7, 42.6 and 18.8 %, respectively. Cells grew at 5-40 °C (optimum, 28-35 °C), pH 6.5-13 (optimum, pH 8-9) and in the presence of 0-13.0 % (w/v) NaCl (optimum, 1 %). The cell wall of strain AK13T contained meso-diaminopimelic acid, and the major isoprenoid quinone was MK-7. Results of fatty acid methyl ester analysis revealed that iso-C15 : 0 was the predominant cellular fatty acid. Two-dimensional thin-layer chromatography analysis indicated that the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and glycolipid. The genotypic and phenotypic characteristics suggested that strain AK13T represented a novel species of the genus Bacillus, and thus the name Bacillus miscanthi sp. nov. is proposed.

Stress responses linked to antimicrobial resistance in Acinetobacter species.

Since the last 20 years, bacteria of the genus Acinetobacter have been the leading cause of hospital-acquired infections. In addition to the ability of Acinetobacter species to acquire rapid antibiotic resistance, limited knowledge on the mechanisms of multidrug resistance to antibiotics limits the treatment options for such infections. Here, we present a review of cellular processes, including oxidative stress defense, energy metabolism, ppGpp signaling, toxin-antitoxin system, and quorum sensing network in Acinetobacter species and their roles in antimicrobial resistance. Although inhibition of stress responses is an attractive approach to the development of effective antimicrobial therapeutic agents, it is crucial to understand the mechanisms that cause antibiotic resistance in Acinetobacter species, as they are not as well studied as those in other pathogenic bacteria. RelA/SpoT has been shown to be involved in ppGpp synthesis in all 50 genomes of 35 Acinetobacter species. However, toxin-antitoxin (TA) systems are present in less than 30% of the 50 genomes (28/30% of SplT/A; 14/14% of HigB/A; 4/6% of HicA/B), except the RelE/B system (30/78%). These data suggested that ppGpp signaling is conserved in Acinetobacter species, but TA systems are not. This review describes our current knowledge on stress responses with respect to antibiotic resistance or tolerance in pathogenic and non-pathogenic Acinetobacter species.

OxyR-controlled surface polysaccharide production and biofilm formation in Acinetobacter oleivorans DR1.

The genomes of several Acinetobacter species possess three distinct polysaccharide-producing operons [two poly-N-acetyl glucosamine (PNAG) and one K-locus]. Using a microfluidic device, an increased amount of polysaccharides and enhanced biofilm formation were observed following continuous exposure to H2O2 and removal of the H2O2-sensing key regulator, OxyR, in Acinetobacter oleivorans DR1 cells. Gene expression analysis revealed that genes located in PNAG1, but not those in PNAG2, were induced and that genes in the K-locus were expressed in the presence of H2O2. Interestingly, the expression of the K-locus gene was enhanced in the PNAG1 mutant and vice versa. The absence of either OxyR or PNAG1 resulted in enhanced biofilm formation, higher surface hydrophobicity, and increased motility, implying that K-locus-driven polysaccharide production in both the oxyR and PNAG1 deletion mutants may be related to these phenotypes. Both the oxyR and K-locus deletion mutants were more sensitive to H2O2 compared with the wildtype and PNAG1 mutant strains. Purified OxyR binds to the promoter regions of both polysaccharide operons with a higher affinity toward the K-locus promoter. Although oxidized OxyR could bind to both promoter regions, the addition of dithiothreitol further enhanced the binding efficiency of OxyR, suggesting that OxyR might function as a repressor for controlling these polysaccharide operons.

Disruption of the polyubiquitin gene Ubb causes retinal degeneration in mice.

We have previously demonstrated that a reduction in ubiquitin (Ub) levels via disruption of the polyubiquitin gene Ubb results in reactive gliosis and hypothalamic neurodegeneration in mice. However, it is not known whether other neural tissues, apart from the brain, can also be affected by Ubb disruption. We examined the retina, which, being derived from the diencephalon, has the same developmental origin as the hypothalamus. We found that expression levels of Ubb were much higher than those of the other polyubiquitin gene Ubc in the retina. In retinal tissues from Ubb knockout (KO) mice, we found that Ubc expression was upregulated to compensate for the loss of Ubb; however, the Ub pool remained disrupted, with reduced levels of free Ub. To directly demonstrate whether the disrupted Ub pools affect neural integrity in retinal tissues, we investigated retinal layers in control and Ubb KO mice. Using optical coherence tomography and histological analysis, we demonstrated that the thickness of the outer nuclear layer of the retina was decreased in Ubb KO mice compared to control mice, suggesting that retinal degeneration was induced by Ub deficiency. Furthermore, the mRNA and protein levels of rhodopsin decreased and those of glial fibrillary acidic protein increased in Ubb KO mouse retinas. Therefore, the maintenance of Ub pools in the retina appears to be crucial for the survival of photoreceptor cells and the prevention of excessive glial cell activation.

Dual anode single-photon avalanche diode for high-speed and low-noise Geiger-mode operation.

The after-pulsing effect is a common problem in high-speed and low-noise single-photon detection based on single-photon avalanche diodes (SPADs). This article presents a dual anode InGaAs/InP SPAD (DA-SPAD) with two separate anode output ports that can be utilized for discriminating relatively weak avalanche signals, providing a simple and robust configuration of the SPAD-based single-photon detection system. Weak avalanche signals with amplitudes below the amplitude of the parasitic capacitive response of the SPAD were easily detected by the DA-SPAD and a simple subtraction circuit. The gated Geiger-mode performance of the DA-SPAD was also investigated. At a gating frequency of 1 GHz, the detection efficiency was 20.4% with an after-pulse probability of 3.5% at a temperature of -20 °C.

Medical diaspora: an underused entity in low- and middle-income countries' health system development.

BACKGROUND: At present, over 215 million people live outside their countries of birth, many of which are referred to as diaspora-those that live in host countries but maintain strong sentimental and material links with their countries of origin, their homelands. The critical shortage of Human Resources for Health (HRH) in many developing countries remains a barrier to attaining their health system goals. Usage of medical diaspora can be one way to meet this need. A growing number of policy-makers have come to acknowledge that medical diaspora can play a vital role in the development of their homeland's health workforce capacity. To date, no inventory of low- and middle-income countries (LMIC) medical diaspora organizations has been done. This paper intends to develop an inventory that is as complete as possible, of the names of the LMIC medical diaspora organizations in the United States of America, the United Kingdom, Canada, and Australia and addresses their interests and roles in building the health system of their country of origin. METHODS: The researchers utilized six steps for their research methodology: (1) development of rationale for choosing the four destination countries (the United States of America, the United Kingdom, Canada, and Australia); (2) identification of low- and middle-income countries (LMIC); (3) web search for the name of LMIC medical diaspora organization in the United States of America, the United Kingdom, Canada, and Australia through the search engines of PubMed, Scopus, Google, Google Scholar, and LexisNexis; (4) development of inclusion and exclusion criteria and creation of a medical diaspora organizations' inventory list (Table 1) and corresponding maps (Figures 1, 2, and 3). Using decision criteria, reviewers narrowed the number to a final 89 organizations; (5) synthesis of information to collect the general as well as the unique roles the medical diaspora organizations play in building health systems; and (6) developing inventory of respective LMIC governments' diaspora offices (Table 2) to identify units/departments that facilitate diaspora's work. RESULT: In total, the authors found 89 medical diaspora organizations in 4 main countries: in the United States of America 60, in the United Kingdom 24, in Australia 3, and in Canada 2. These medical diaspora organizations tend to have three focuses: providing healthcare services, training, and when needed humanitarian aid to their home country; creating a social or professional network of migrant physicians (i.e., simply to bring together people with an ethnic and professional commonality) and; supplying improved and culturally sensitive healthcare to the migrant population within the host country. Sixty-eight LMIC countries have established a diaspora office within their government office. It is also equally important to note that many policy-makers may lack knowledge of models for medical diaspora engagement or of valuable lessons learned by other governments about working with diaspora. CONCLUSIONS: The medical diaspora remains an underutilized resource in both health systems policy formulation and program implementation.

Lineage-specific SoxR-mediated Regulation of an Endoribonuclease Protects Non-enteric Bacteria from Redox-active Compounds.

Bacteria use redox-sensitive transcription factors to coordinate responses to redox stress. The [2Fe-2S] cluster-containing transcription factor SoxR is particularly tuned to protect cells against redox-active compounds (RACs). In enteric bacteria, SoxR is paired with a second transcription factor, SoxS, that activates downstream effectors. However, SoxS is absent in non-enteric bacteria, raising questions as to how SoxR functions. Here, we first show that SoxR of Acinetobacter oleivorans displayed similar activation profiles in response to RACs as did its homolog from Escherichia coli but controlled a different set of target genes, including sinE, which encodes an endoribonuclease. Expression, gel mobility shift, and mutational analyses indicated that sinE is a direct target of SoxR. Redox potentials and permeability of RACs determined optimal sinE induction. Bioinformatics suggested that only a few γ- and ß-proteobacteria might have SoxR-regulated sinE Purified SinE, in the presence of Mg2+ ions, degrades rRNAs, thus inhibiting protein synthesis. Similarly, pretreatment of cells with RACs demonstrated a role for SinE in promoting persistence in the presence of antibiotics that inhibit protein synthesis. Our data improve our understanding of the physiology of soil microorganisms by suggesting that both non-enteric SoxR and its target SinE play protective roles in the presence of RACs and antibiotics.

Methylobacterium currus sp. nov., isolated from a car air conditioning system.

A novel bacterial strain, designated PR1016AT, was isolated from a car air conditioning system. This rod-shaped strain showed catalase and oxidase activities, was aerobic and methylotrophic, and had a reddish pink colour. The genomic DNA G+C content of strain PR1016AT was 70.2 mol%, as determined by genome sequencing. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain PR1016AT was most closely related to Methylobacterium aquaticum GR16T (98.86 %), M. variabile GR3T (98.43 %), M. platani PMB 02T (98.36 %) and M. tarhaniae N4211T (98.14 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain PR1016AT and M. aquaticum GR16T, M. platani PMB02T and M. variabile GR3T were 88.61, 88.14 and 87.88 %, and 36.4, 35.8 and 34.7 %, respectively. Numerous insertion sequences are present in the genome of strain PR1016AT, which has a larger genome than the four Methylobacterium species described above. Cells grew at 18-42 °C (optimum, 30 °C), at pH 4.0-9.0 (optimum, pH 7.0) and in the presence of 0-1.0 % (w/v) NaCl (optimum, 0 %). The major respiratory quinone was Q10. Fatty acid methyl ester analysis revealed that summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) was the predominant cellular fatty acid in strain PR1016AT. Two-dimensional TLC indicated that the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The genotypic and phenotypic characteristics indicate that strain PR1016AT represents a novel species of the genus Methylobacterium, for which the name Methylobacterium currus sp. nov. is proposed. The type strain is PR1016AT (=KACC 19662T=JCM 32670T).

4-Hydroxybenzaldehyde sensitizes Acinetobacter baumannii to amphenicols.

Bacterial metabolism modulated by environmental chemicals could alter antibiotic susceptibility. 4-Hydroxybenzaldehyde (4-HBA), which cannot support the growth of Acinetobacter baumannii, exhibited synergism only with amphenicol antibiotics including chloramphenicol (CAM) and thiamphenicol. Interestingly, this synergistic effect was not observed with other growth-supporting, structurally similar compounds such as 4-hydroxybenzoate. Transcriptomic analysis demonstrated that genes involved in protocatechuate metabolism (pca genes) and osmotic stress (bet genes) were significantly upregulated by 4-HBA and CAM treatment. The 14C-labeled CAM influx was lower in a pcaK1 (encoding a transporter of protocatechuate) deletion mutant and was higher in the pcaK1 overexpressing cells relative to that in the wild type upon 4-HBA treatment. Our kinetic data using 14C-labeled CAM clearly showed that CAM uptake is possibly through facilitated diffusion. Deletion of pcaK1 did not result in the elimination of CAM influx, indicating that CAM does not enter only through PcaK1. The amount of 4-HBA in the culture supernatant was, however, unaffected during the test conditions, validating that it was not metabolized by the bacteria. CAM resistant A. baumannii cells derived by serial passages through CAM-amended media exhibited lower level of pcaK1 gene expression. These results led us to conclude that the activation of PcaK1 transporter is probably linked to cellular CAM susceptibility. This is the first report showing a relationship between CAM influx and aromatic compound metabolism in A. baumannii.

Bias-Voltage Stabilizer for HVHF Amplifiers in VHF Pulse-Echo Measurement Systems.

The impact of high-voltage-high-frequency (HVHF) amplifiers on echo-signal quality is greater with very-high-frequency (VHF, ≥100 MHz) ultrasound transducers than with low-frequency (LF, ≤15 MHz) ultrasound transducers. Hence, the bias voltage of an HVHF amplifier must be stabilized to ensure stable echo-signal amplitudes. We propose a bias-voltage stabilizer circuit to maintain stable DC voltages over a wide input range, thus reducing the harmonic-distortion components of the echo signals in VHF pulse-echo measurement systems. To confirm the feasibility of the bias-voltage stabilizer, we measured and compared the deviations in the gain of the HVHF amplifier with and without a bias-voltage stabilizer. Between -13 and 26 dBm, the measured gain deviations of a HVHF amplifier with a bias-voltage stabilizer are less than that of an amplifier without a bias-voltage stabilizer. In order to confirm the feasibility of the bias-voltage stabilizer, we compared the pulse-echo responses of the amplifiers, which are typically used for the evaluation of transducers or electronic components used in pulse-echo measurement systems. From the responses, we observed that the amplitudes of the echo signals of a VHF transducer triggered by the HVHF amplifier with a bias-voltage stabilizer were higher than those of the transducer triggered by the HVHF amplifier alone. The second, third, and fourth harmonic-distortion components of the HVHF amplifier with the bias-voltage stabilizer were also lower than those of the HVHF amplifier alone. Hence, the proposed scheme is a promising method for stabilizing the bias voltage of an HVHF amplifier, and improving the echo-signal quality of VHF transducers.