bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of a 2-Week High-Intensity Training Camp on Sleep Activity of Professional Rugby League Athletes
Authors: Thornton Heidi R. , Duthie Grant M. , Pitchford Nathan W. , Delaney Jace A. , Benton Dean T. , Dascombe Ben J.
Published: December 2016

Purpose:

To investigate the effects of a training camp on the sleep characteristics of professional rugby league players compared with a home period.

Methods:

During a 7-d home and 13-d camp period, time in bed (TIB), total sleep time (TST), sleep efficiency (SE), and wake after sleep onset were measured using wristwatch actigraphy. Subjective wellness and training loads (TL) were also collected. Differences in sleep and TL between the 2 periods and the effect of daytime naps on nighttime sleep were examined using linear mixed models. Pearson correlations assessed the relationship of changes in TL on individuals’ TST.

Results:

During the training camp, TST (–85 min), TIB (–53 min), and SE (–8%) were reduced compared with home. Those who undertook daytime naps showed increased TIB (+33 min), TST (+30 min), and SE (+0.9%). Increases in daily total distance and training duration above individual baseline means during the training camp shared moderate (r = –.31) and trivial (r = –.04) negative relationships with TST.

Conclusions:

Sleep quality and quantity may be compromised during training camps; however, daytime naps may be beneficial for athletes due to their known benefits, without being detrimental to nighttime sleep.
VO2 at Maximal and Supramaximal Intensities: Lessons to High-Intensity Interval Training in Swimming
Authors: Sousa Ana , Vilas-Boas João Paulo , Fernandes Ricardo J. , Figueiredo Pedro
Published: December 2016

Purpose:

To establish appropriate work intensity for interval training that would elicit maximal oxygen uptake (VO2max) for well-trained swimmers.

Methods:

Twelve male competitive swimmers completed an incremental protocol to determine the minimum velocity at VO2max (νVO2max) and, in randomized order, 3 square-wave exercises from rest to 95%, 100%, and 105% of νVO2max. Temporal aspects of the VO2 response were examined in these latter.

Results:

Swimming at 105% of νVO2max took less (P < .04) absolute time to achieve 90%, 95%, and 100% of VO2max intensities (35.0 ± 7.7, 58.3 ± 15.9, 58.3 ± 19.3 s) compared with 95% (72.1 ± 34.3, 106.7 ± 43.9, 151.1 ± 52.4 s) and 100% (55.8 ± 24.5, 84.2 ± 35.4, 95.6 ± 29.8 s) of VO2max. However, swimming at 95% of νVO2max resulted in longer absolute time (P < .001) at or above the desired intensities (90%: 268.3 ± 72.5 s; 95%: 233.8 ± 74.3 s; 100%: 173.6 ± 78.2 s) and more relative time at or above 95% of VO2max than 105% of νVO2max (68.6% ± 13.5% vs 55.3% ± 11.5%, P < .03), and at or above 100% of VO2max than 100% and 105% of νVO2max (52.7% ± 16.3% vs 28.2% ± 10.5% and 34.0% ± 11.3%, P < .001). At 60 s of effort, swimmers achieved 85.8% ± 11.2%, 88.3% ± 5.9%, and 94.7% ± 5.5% of the VO2max when swimming at 95%, 100%, and 105% of νVO2max, respectively.

Conclusions:

When training to elicit VO2max, using higher swimming intensities will promote a faster VO2 response but a shorter time spent above these intensities. However, lower intensities allow maintaining the desired response for a longer period of time. Moreover, using the 60-s time period seem to be a more adequate stimulus than shorter ones (~30-s), especially when performed at 105% of νVO2max intensity.
Validation of Inertial Measurement Units for Upper Body Kinematics
Authors: Morrow Melissa M.B. , Lowndes Bethany , Fortune Emma , Kaufman Kenton R. , Hallbeck M. Susan
Published: December 2016

The purpose of this study was to validate a commercially available inertial measurement unit (IMU) system against a standard lab-based motion capture system for the measurement of shoulder elevation, elbow flexion, trunk flexion/extension, and neck flexion/extension kinematics. The validation analyses were applied to 6 surgical faculty members performing a standard, simulated surgical training task that mimics minimally invasive surgery. Three-dimensional joint kinematics were simultaneously recorded by an optical motion capture system and an IMU system with 6 sensors placed on the head, chest, and bilateral upper and lower arms. The sensor-to-segment axes alignment was accomplished manually. The IMU neck and trunk IMU flexion/extension angles were accurate to within 2.9 ± 0.9 degrees and 1.6 ± 1.1°, respectively. The IMU shoulder elevation measure was accurate to within 6.8 ± 2.7° and the elbow flexion measure was accurate to within 8.2 ± 2.8°. In the Bland-Altman analyses, there were no significant systematic errors present; however, there was a significant inversely proportional error across all joints. As the gold standard measurement increased, the IMU underestimated the magnitude of the joint angle. This study reports acceptable accuracy of a commercially available IMU system; however, results should be interpreted as protocol specific.
The Advantages of Normalizing Electromyography to Ballistic Rather than Isometric or Isokinetic Tasks
Authors: Suydam Stephen M. , Manal Kurt , Buchanan Thomas S.
Published: December 2016

Isometric tasks have been a standard for electromyography (EMG) normalization stemming from anatomic and physiologic stability observed during contraction. Ballistic dynamic tasks have the benefit of eliciting maximum EMG signals for normalization, despite having the potential for greater signal variability. It is the purpose of this study to compare maximum voluntary isometric contraction (MVIC) to nonisometric tasks with increasing degrees of extrinsic variability, ie, joint range of motion, velocity, rate of contraction, etc., to determine if the ballistic tasks, which elicit larger peak EMG signals, are more reliable than the constrained MVIC. Fifteen subjects performed MVIC, isokinetic, maximum countermovement jump, and sprint tasks while EMG was collected from 9 muscles in the quadriceps, hamstrings, and lower leg. The results revealed the unconstrained ballistic tasks were more reliable compared to the constrained MVIC and isokinetic tasks for all triceps surae muscles. The EMG from sprinting was more reliable than the constrained cases for both the hamstrings and vasti. The most reliable EMG signals occurred when the body was permitted its natural, unconstrained motion. These results suggest that EMG is best normalized using ballistic tasks to provide the greatest within-subject reliability, which beneficially yield maximum EMG values.
Feasibility and Efficacy of the AgingPlus Program: Changing Views on Aging to Increase Physical Activity
Authors: Brothers Allyson , Diehl Manfred
Published: December 2016

This study evaluated the feasibility and efficacy of the AgingPlus intervention program. AgingPlus is an 8-week multi-component motivational program which promotes increased physical activity by targeting adults’ negative views on aging (NVOA) and perceptions of control, two known psychological barriers to physical exercise. A total of 62 adults, ages 50–82 years, participated in this feasibility study. We assessed NVOA, perceptions of control, and physical activity level at baseline (Week 0), immediate posttest (Week 4), and delayed posttest (Week 12). High attendance rates, low attrition, and positive participant feedback indicated that the program had high acceptability. Repeated measures multivariate analyses of variance (RM-MANOVA) showed statistically significant and substantively meaningful improvements in NVOA, control beliefs, and physical activity from pretest to immediate and delayed posttest. The program effects did not differ between those younger or older than age 65. These findings provide promising support for the feasibility and efficacy of the AgingPlus program.
Racial/Ethnic Differences in the Associations Between Physical Activity and Sleep Duration: A Population-Based Study
Authors: Murillo Rosenda , Lambiase Maya J. , Rockette-Wagner Bonny J. , Kriska Andrea M. , Haibach Jeffrey P. , Thurston Rebecca C.
Published: December 2016

Background:

This study examined associations between physical activity (recreational, nonrecreational) and sleep duration among a nationally representative diverse sample of U.S. adults.

Methods:

We used cross-sectional data from 9,205 National Health and Nutrition Examination Survey 2007 to 2012 participants aged 20 to 65 years who identified as White, Black, or Hispanic. Activity (ie, recreation, occupation, and transportation activity) was categorized into quartiles. Sleep duration was categorized as short (≤6 hours/night) or normal (>6 to ≤9 hours/night). Logistic regression was used to estimate associations of activity with sleep duration.

Results:

Recommended levels of recreation activity and moderate levels of transportation activity were associated with normal sleep duration [Odds Ratio (OR): = 1.33, 95% Confidence Interval (CI) = 1.08, 1.65; OR = 1.28, 95% CI = 1.02, 1.62, respectively]. High occupation physical activity was associated with shorter sleep duration (OR = 0.59, 95% CI = 0.49, 0.71). Differences were observed by race/ethnicity in associations of recreation and occupation activity with sleep duration.

Conclusions:

White individuals who engaged in some recreation activity, relative to being inactive, had more favorable sleep duration; whereas, high levels of occupation activity were associated with worse sleep duration among White and Black individuals. Physical activity was not associated with sleep duration among Hispanics.
Utility of Surveillance Research to Inform Physical Activity Policy: An Exemplar From Canada
Authors: Craig Cora L. , Cameron Christine A. , Bauman Adrian
Published: December 2016

Background:

There are several well-known risk factor monitoring systems, but few examples of comprehensive surveillance systems designed specifically to inform physical activity (PA) policy. This paper examines the utility of Canada`s Physical Activity and Sport Monitoring System in guiding policy and practice.

Methods:

Indicators were determined in conjunction with government, nongovernmental associations and academics. Serial measures were collected from representative population (telephone interviews, n = 4000 to 11,000) and setting-based (postal surveys, n = 1425 to 4304) surveys.

Results:

Adult PA was higher in 2014 (47%) than 1998 (37%). The prevalence of knowledge about sufficient PA to meet national guidelines increased (31% to 57%). Most adults (66%) reported having many safe places to walk locally. Having policies to encourage walking and cycling when redeveloping communities increased by community size (5% to 37%). PA promotion was available in 10% to 15% of workplaces. Most parents (64%) provided transportation to support their child’s PA. The prevalence of policies mandating daily PE increased 2001 to 2011 (36% to 55%), as did having no policy to hire qualified PE teachers (25% to 34%).

Conclusions:

Canada’s surveillance system has provided information for guiding policy planning, resource allocation, setting and tracking national goals, assessing changes in PA determinants, and evaluating national campaigns, naturally occurring experiments, and innovative policies.
Associations Between Physical Activity and Depressive Symptoms by Weight Status Among Adults With Type 2 Diabetes: Results From Diabetes MILES–Australia
Authors: Craike Melinda J. , Mosely Kylie , Browne Jessica L. , Pouwer Frans , Speight Jane
Published: December 2016

Background:

To examine associations between physical activity (PA) and depressive symptoms among adults with type 2 diabetes mellitus (Type 2 DM), and whether associations varied according to weight status.

Methods:

Diabetes MILES–Australia is a national survey of adults with diabetes, focused on behavioral and psychosocial issues. Data from 705 respondents with Type 2 DM were analyzed, including: demographic and clinical characteristics, PA (IPAQ-SF), depressive symptoms (PHQ-9), and BMI (self-reported height and weight). Data analysis was performed using ANCOVA.

Results:

Respondents were aged 59 ± 8 years; 50% women. PA was negatively associated with depressive symptoms for the overall sample (ηp2= 0.04,P < .001) and all weight categories separately: healthy (ηp2 0.11 P = .041,), overweight (ηp2= 0.04, P = .025) and obese (ηp2 = 0.03, P = .007). For people who were healthy (BMI 18.5 to 24.9) or overweight (BMI 25 to 29.9), high amounts of PA were significantly associated with fewer depressive symptoms; for adults who were obese (BMI ≥ 30) however, both moderate and high amounts were associated with fewer depressive symptoms.

Conclusions:

PA is associated with fewer depressive symptoms among adults with Type 2DM, however the amount of PA associated with fewer depressive symptoms varies according to weight status. Lower amounts of PA might be required for people who are obese to achieve meaningful reductions in depressive symptoms compared with those who are healthy weight or overweight. Further research is needed to establish the direction of the relationship between PA and depressive symptoms.
Sedentary Time, Physical Activity, and Executive Function in a Longitudinal Study of Youth
Authors: Wickel Eric E.
Published: December 2016

Background:

This study examined associations between sedentary time, physical activity (PA), and executive function among youth participating in the Study of Early Child Care and Youth Development.

Methods:

Sedentary time and PA (light, moderate, vigorous, and moderate-to-vigorous (MVPA)) were objectively assessed at 9 and 15 years, while executive function (inhibition, working memory, and fluid intelligence) were assessed at 15 years. Regression models were used to examine associations.

Results:

Sedentary time at 9 years predicted fluid intelligence at 15 years (B = 0.031), whereas increased sedentary time from 9 to 15 years predicted higher inhibition (B = 0.003), working memory (B = 0.074), and fluid intelligence (B = 0.029). Relatively lower levels of working memory at 15 years were predicted from increased levels of light PA, moderate PA, and MVPA from 9 to 15 years (B = –0.075, –0.293, and –0.173, respectively). At 15 years, inhibition, working memory, and fluid intelligence were significantly associated with sedentary time (B = 0.003, 0.055, and 0.045, respectively).

Conclusions:

Childhood sedentary time and PA may affect executive function at 15 years; however, prospective studies are needed to examine the concurrent change in both sedentary time and PA with executive function.
Validation of Questionnaire-Assessed Physical Activity in Comparison With Objective Measures Using Accelerometers and Physical Performance Measures Among Community-Dwelling Adults Aged ≥85 Years in Tokyo, Japan
Authors: Oguma Yuko , Osawa Yusuke , Takayama Michiyo , Abe Yukiko , Tanaka Shigeho , Lee I-Min , Arai Yasumichi
Published: December 2016

Background:

To date, there is no physical activity (PA) questionnaire with convergent and construct validity for the oldest-old. The aim of the current study was to investigate the validity of questionnaire-assessed PA in comparison with objective measures determined by uniaxial and triaxial accelerometers and physical performance measures in the oldest-old.

Methods:

Participants were 155 elderly (mean age 90 years) who were examined at the university and agreed to wear an accelerometer for 7 days in the 3-year-follow-up survey of the Tokyo Oldest-Old Survey of Total Health. Fifty-nine participants wore a uniaxial and triaxial accelerometer simultaneously. Self-rated walking, exercise, and household PA were measured using a modified Zutphen PA Questionnaire (PAQ). Several physical performance tests were done, and the associations among PAQ, accelerometer-assessed PA, and physical performances were compared by Spearman’s correlation coefficients.

Results:

Significant, low to moderate correlations between PA measures were seen on questionnaire and accelerometer assessments (ρ = 0.19 to 0.34). Questionnaireassessed PA measure were correlated with a range of lower extremity performance (ρ = 0.21 to 0.29).

Conclusions:

This PAQ demonstrated convergent and construct validity. Our findings suggest that the PAQ can reasonably be used in this oldest-old population to rank their PA level.
Racial/Ethnic and Income Differences in Obesity Among Older Adults: The Role of Leisure-time Physical Activity and Neighborhood Social Cohesion
Authors: Yu Chia-Yuan
Published: December 2016

Background:

Few studies have examined the associations among social cohesion, physical activity, and obesity in older adults. This study explored the influences of social cohesion and leisure-time physical activity on obesity in older adults, and tested whether these relationships varied by race/ethnicity and income level.

Methods:

A cross-sectional analysis of adults in the 2013 National Health Interview Study (NHIS) who were over 65 years of age (N = 7714) was used. Logistic regressions were performed to examine the impacts of social cohesion and physical activity on obesity, and the relative risks (RR) were reported.

Results:

The median age was 73 years old, and 59.8% of respondents were female; 23.8% met the recommended level of moderate physical activity. Neighborhood social cohesion was not associated with obesity for older adults. Meeting the recommended level of vigorous physical activity was related to a lower probability of obesity only for older Hispanic adults (RR = 0.41, 95% CI: 0.31 to 0.50), while older adults were less likely to be obese if they met the recommended level of moderate physical activity.

Conclusions:

Increasing the level of physical activity may profoundly reduce the probability of obesity for older adults. Moreover, the results implied the need for future physical activity interventions for minorities.
Physical and genetic map of the major nif gene cluster from Azotobacter vinelandii
Authors: Jacobson M R , Brigle K E , Bennett L T , Setterquist R A , Wilson M S , Cash V L , Beynon J , Newton W E , Dean D R
Published: December 2016

Determination of a 28,793-base-pair DNA sequence of a region from the Azotobacter vinelandii genome that includes and flanks the nitrogenase structural gene region was completed. This information was used to revise the previously proposed organization of the major nif cluster. The major nif cluster from A. vinelandii encodes 15 nif-specific genes whose products bear significant structural identity to the corresponding nif-specific gene products from Klebsiella pneumoniae. These genes include nifH, nifD, nifK, nifT, nifY, nifE, nifN, nifX, nifU, nifS, nifV, nifW, nifZ, nifM, and nifF. Although there are significant spatial differences, the identified A. vinelandii nif-specific genes have the same sequential arrangement as the corresponding nif-specific genes from K. pneumoniae. Twelve other potential genes whose expression could be subject to nif-specific regulation were also found interspersed among the identified nif-specific genes. These potential genes do not encode products that are structurally related to the identified nif-specific gene products. Eleven potential nif-specific promoters were identified within the major nif cluster, and nine of these are preceded by an appropriate upstream activator sequence. A + T-rich regions were identified between 8 of the 11 proposed nif promoter sequences and their upstream activator sequences. Site-directed deletion-and-insertion mutagenesis was used to establish a genetic map of the major nif cluster.
Role of the flagellum in cell-cycle-dependent expression of bacteriophage receptor activity in Caulobacter crescentus
Authors: Bender R A , Refson C M , O'Neill E A
Published: December 2016

The rate of adsorption of Caulobacter bacteriophage phi CbK to Caulobacter crescentus is dependent on the structural integrity of the flagellum. Cells lacking part or all of the flagellum because of either mutation or mechanical shear were defective in adsorption, and the extent of the defect in adsorption reflected the amount of flagellar structure missing. Maximal adsorption rates were also dependent on cellular motility and energy metabolism, since adsorption to cells with paralyzed flagella was slower than adsorption to motile cells and inhibition of cellular energy metabolism with azide also reduced adsorption rates, even for nonmotile cells. Nevertheless, the flagellum is not the receptor for phage phi CbK, since flagellumless mutants adsorbed phi CbK at detectable rates. While some portion of the fluctuation in the phi CbK receptor activity during the C. crescentus cell cycle can be ascribed to the periodicity of flagellar loss and reappearance, the phage receptor activity remaining in flagellumless mutants was periodic in the cell cycle. Therefore, the periodic expression of phage receptor activity is an intrinsic property of the C. crescentus cell cycle, although the amplitude of the oscillation may be altered by the periodic expression of flagellar motility.
Roles of glycerol and glycerol-3-phosphate dehydrogenase (NAD+) in acquired osmotolerance of Saccharomyces cerevisiae
Authors: Blomberg A , Adler L
Published: December 2016

In a cell culture of Saccharomyces cerevisiae exponentially growing in basal medium, only 0.02% of the cells were osmotolerant, i.e., survived transfer to medium containing 1.4 M NaCl. Short-time conditioning in 0.7 M NaCl medium transformed the whole population into an osmotolerance phenotype. During this conditioning, the rate of formation of glycerol, the main compatible solute in S. cerevisiae, increased threefold and the specific activity of glycerol-3-phosphate dehydrogenase (NAD+) (GPDH) (EC 1.1.1.8) was enhanced sixfold. The apparent flux control coefficient for GPDH in the formation of glycerol was estimated to be 0.6. Glycerol production was also favored by regulated activities of alcohol dehydrogenase (EC 1.1.1.1) and aldehyde dehydrogenase [NAD(P)]+ (EC 1.2.1.5). About 50% of the total glycerol produced during conditioning in 0.7 M NaCl was retained intracellularly, and the increased glycerol accumulation was shown to be not merely a result of enhanced production rate but also of increased retention of glycerol. Washing the cells with solutions of lower salinities resulted in loss of glycerol, with retained levels proportional to the concentration of NaCl in the washing solution. Cycloheximide addition inhibited the development of acquired osmotolerance and conditioned cells washed free of glycerol retained a high degree of osmotolerance, which indicate that protein synthesis was required to establish the osmotolerance state.
An rpoN-like gene of Alcaligenes eutrophus and Pseudomonas facilis controls expression of diverse metabolic pathways, including hydrogen oxidation
Authors: Römermann D , Warrelmann J , Bender R A , Friedrich B
Published: December 2016

Pleiotropic mutants of Alcaligenes eutrophus with the phenotype Hno- have been characterized previously. They are deficient in several diverse metabolic activities, including hydrogen oxidation, nitrate and urea assimilation, denitrification, and various substrate transport systems. Phenotypically similar mutants were identified among hydrogenase-deficient strains of Pseudomonas facilis. The Tn5-labeled hno gene was cloned from a genomic DNA library of A. eutrophus and used to identify the corresponding unimpaired wild-type DNA sequence. The recombinant plasmid pCH148 contained an insert of 12.3 kilobase pairs and was shown to restore the Hno+ phenotype to mutants of A. eutrophus and P. facilis. A cosmid isolated from a DNA library of P. facilis also exhibited intergeneric Hno-complementing activity. The cloned hno loci from both organisms showed DNA homology by Southern blot hybridization. A subclone of pCH148 which contained a 6.5-kilobase-pair insert was constructed. The resulting hybrid, pCH170, not only was able to complement Hno- mutants but also relieved glutamine auxotrophy in NtrA- mutants of enteric bacteria. This suggests that the hno gene product from A. eutrophus is functionally similar to the NtrA protein, which has been identified as a novel sigma factor (sigma 54) of RNA polymerase.
Genetic analysis of chromosomal mutations in the polysialic acid gene cluster of Escherichia coli K1
Authors: Vimr E R , Aaronson W , Silver R P
Published: December 2016

The kps gene cluster of Escherichia coli K1 encodes functions for sialic acid synthesis, activation, polymerization, and possibly translocation of polymer to the cell surface. The size and complexity of this membrane polysaccharide biosynthetic cluster have hindered genetic mapping and functional descriptions of the kps genes. To begin a detailed investigation of the polysialic acid synthetic mechanism, acapsular mutants were characterized to determine their probable defects in polymer synthesis. The mutants were tested for complementation with kps fragments subcloned from two separately isolated, functionally intact kps gene clusters. Complementation was assayed by immunological and biochemical methods and by sensitivity to the K1-specific bacteriophage K1F. The kps cluster consisted of a central 5.8-kilobase region that contained at least two genes coding for sialic acid synthetic enzymes, a gene encoding the sialic acid-activating enzyme, and a gene encoding the sialic acid polymerase. This biosynthetic region is flanked on one side by an approximately 2.8-kilobase region that contains a potential regulatory locus and at least one structural gene for a polypeptide that appears to function in polysialic acid assembly. Flanking the biosynthetic region on the opposite side is a 6- to 8.4-kilobase region that codes for at least three proteins which may also function in polymer assembly and possibly in translocating polymer to the outer cell surface. Results of transduction crosses supported these conclusions and indicated that some of the kps genes flanking the central biosynthetic region may not function directly in transporting polymer to the cell surface. The results also demonstrate that the map position and probable function of most of the kps cluster genes have been identified.
Mechanism of L-glutamate transport in membrane vesicles from Bacillus stearothermophilus
Authors: de Vrij W , Bulthuis R A , van Iwaarden P R , Konings W N
Published: December 2016

In the presence of electrochemical energy, several branched-chain neutral and acidic amino acids were found to accumulate in membrane vesicles of Bacillus stearothermophilus. The membrane vesicles contained a stereo-specific transport system for the acidic amino acids L-glutamate and L-aspartate, which could not translocate their respective amines, L-glutamine and L-asparagine. The transport system was thermostable (Ti = 70 degrees C) and showed highest activities at elevated temperatures (60 to 65 degrees C). The membrane potential or pH gradient could act as the driving force for L-glutamate uptake, which indicated that the transport process of L-glutamate is electrogenic and that protons are involved in the translocation process. The electrogenic character implies that the anionic L-glutamate is cotransported with at least two monovalent cations. To determine the mechanistic stoichiometry of L-glutamate transport and the nature of the cotranslocated cations, the relationship between the components of the proton motive force and the chemical gradient of L-glutamate was investigated at different external pH values in the absence and presence of ionophores. In the presence of either a membrane potential or a pH gradient, the chemical gradient of L-glutamate was equivalent to that specific gradient at different pH values. These results cannot be explained by cotransport of L-glutamate with two protons, assuming thermodynamic equilibrium between the driving force for uptake and the chemical gradient of the substrate. To determine the character of the cotranslocated cations, L-glutamate uptake was monitored with artificial gradients. It was established that either the membrane potential, pH gradient, or chemical gradient of sodium ions could act as the driving force for L-glutamate uptake, which indicated that L-glutamate most likely is cotranslocated in symport with one proton and on sodium ion.
Replication and segregational stability of Bacillus plasmid pBAA1
Authors: Devine K M , Hogan S T , Higgins D G , McConnell D J
Published: December 2016

A cryptic plasmid, pBAA1, was identified in an industrial Bacillus strain. The plasmid is 6.8 kilobases in size and is present in cells at a copy number of approximately 5 per chromosome equivalent. The plasmid has been maintained under industrial fermentation conditions without apparent selective pressure and so is assumed to be partition proficient. The minimal replicon was localized to a 1.4-kilobase fragment which also contains the functions required for copy number control. The very low level of segregational instability of the minimal replicon suggests that it also contains functions involved in plasmid maintenance. Comparison with other plasmids indicates that pBAA1 belongs to the group of small gram-positive plasmids which replicate by a rolling cycle-type mechanism. A sequence was identified which is required for the efficient conversion of the single plus strand to the double-stranded form during plasmid replication. Deletion of this sequence resulted in a low level of segregational plasmid instability.
Uptake and acylation of 2-acyl-lysophospholipids by Escherichia coli
Authors: Hsu L , Jackowski S , Rock C O
Published: December 2016

The efficiency of extracellular 2-acyl-lysophospholipid incorporation into Escherichia coli membranes and the acyl donor utilized to acylate the 2-acyl-lysophospholipid was determined. Exogenous 2-acyl-lysophospholipids were acylated via the acyl-acyl carrier protein synthetase/2-acylglycerophosphoethanolamine acyltransferase pathway. The maximum extent of 2-acyl-lysophospholipid incorporation into the membrane was approximately 2.5% of the normal phospholipid biosynthetic rate.
Transformation-deficient mutants of piliated Neisseria gonorrhoeae
Authors: Biswas G D , Lacks S A , Sparling P F
Published: December 2016

Seven transformation-deficient mutants of piliated, competent Neisseria gonorrhoeae were isolated by screening them for their inability to be transformed by chromosomal DNA after chemical mutagenesis. Three distinct classes of mutants were obtained, each of which was piliated, as determined by electron microscopy. One class exhibited abnormal colony morphology and was unable to take up DNA into a DNase-resistant state. A second class was morphologically normal and took up DNA into a DNase-resistant state normally, but was deficient in both chromosomal and plasmid transformation; mutations in these mutants may affect entry of DNA into the cell proper. A third class was similar to the second but was fully competent for plasmid transformation, suggesting that there was a defect in a late stage of chromosomal transformation.
Identification and cloning of the conjugative transfer region of Staphylococcus aureus plasmid pGO1
Authors: Thomas W D , Archer G L
Published: December 2016

The conjugative transfer (tra) genes of a 52-kilobase (kb) staphylococcal plasmid, pGO1, were localized by deletion analysis and transposon insertional inactivation. All transfer-defective (Tra-) deletions and Tn551 or Tn917 transposon insertions occurred within a 14.5-kb BglII fragment. Deletions and insertions outside this fragment all left the plasmid transfer proficient (Tra+). The tra region was found to be flanked by directly repeated DNA sequences, approximately 900 base pairs in length, at either end. Clones containing the 14.5-kb BglII fragment (pGO200) and subclones from this fragment were constructed in Escherichia coli on shuttle plasmids and introduced into Staphylococcus aureus protoplasts. Protoplasts could not be transformed with pGO200E (pGO200 on the staphylococcal replicon, pE194) or subclones containing DNA at one end of the tra fragment unless pGO1 or specific cloned tra DNA fragments were present in the recipient cell. However, once stabilized by sequences present on a second replicon, each tra fragment could be successfully introduced alone into other plasmid-free S. aureus recipients by conjugative mobilization or transduction. In this manner, two clones containing overlapping fragments comprising the entire 14.5-kb BglII fragment were shown to complement each other. The low-frequency transfer resulted in transconjugants containing one clone intact, deletions of that clone, and recombinants of the two clones. The resulting recombinant plasmid (pGO220), which regenerated the tra region intact on a single replicon, transferred at frequencies comparable to those of pGO1. Thus, all the genes necessary and sufficient for conjugative transfer of pGO1 are contained within a 14.5-kb region of DNA.
Regulation of transcription of the Bacillus subtilis spoIIA locus
Authors: Wu J J , Howard M G , Piggot P J
Published: December 2016

The start point of spoIIA transcription was defined by primer extension analysis with two separate primers. It was 27 bases upstream from the putative translation initiation codon of the first open reading frame in the spoIIA locus. A region extending at least 52 bases upstream from the transcription start site was necessary for transcription, as determined with integrative plasmids. Transcription of spoIIA was dependent on the spoOA, spoOB, and spoOF loci, but this dependency was partly overcome by increasing the number of copies of the spoIIA promoter region. Transcription of spoIIA was absolutely dependent on the spoOH locus, which codes for the RNA polymerase sigma factor sigma H. Regions approximately -35 and -10 upstream from the spoIIA transcription start site showed sequence homology with Bacillus subtilis sigma H promoters.
Identification and isolation of genes essential for H2 oxidation in Rhodobacter capsulatus
Authors: Xu H W , Love J , Borghese R , Wall J D
Published: December 2016

Mutants of Rhodobacter capsulatus unable to grow photoautotrophically with H2 and CO2 were isolated. Those lacking uptake hydrogenase activity as measured by H2-dependent methylene blue reduction were analyzed genetically and used in complementation studies for the isolation of the wild-type genes. Results of further subcloning and transposon Tn5 mutagenesis suggest the involvement of a minimum of five genes. Hybridization to the 2.2-kilobase-pair SstI fragment that lies within the coding region for the large and small subunits of Bradyrhizobium japonicum uptake hydrogenase showed one region of strong homology among the R. capsulatus fragments isolated, which we interpret to mean that one or both structural genes were among the genes isolated.
Molecular characterization and protein analysis of the cap region, which is essential for encapsulation in Bacillus anthracis
Authors: Makino S , Uchida I , Terakado N , Sasakawa C , Yoshikawa M
Published: December 2016

By using genetic complementation tests with various in vitro-constructed mutants with mutations in the cap region (which is essential for encapsulation in Bacillus anthracis), we identified three cistrons, capB, capC, and capA, in this order of arrangement. Minicell analysis revealed that these cistrons produce proteins of 44, 16, and 46 kilodaltons, respectively. The complete nucleotide sequence of 3,244 base pairs covering the whole cap region was determined and revealed the existence of the three open reading frames of capB (397 amino acid residues; molecular weight, 44,872), capC (149 amino acid residues; molecular weight, 16,522), and capA (411 amino acid residues; molecular weight, 46,420) arranged in the order predicted by complementation tests. These three cistrons were all transcribed in the same direction from promoters unique to each cistron. Judging from the predicted amino acid sequence of the three proteins and from their localization and their sensitivity to various physicochemical treatments, they appeared to be membrane-associated enzymes mediating the polymerization of D-glutamic acid via the membrane. Capsular peptides immunologically identical to that of B. anthracis were found in B. subtilis, B. megaterium, and B. licheniformis, but no sequence homologous to the cap region was found in any of these bacilli other than B. anthracis. Using strains of B. anthracis with or without insertional inactivation of the cap region, we found that the capsule of B. anthracis conferred strong resistance to phagocytosis upon the bacterial host.
Permeability of Rickettsia prowazekii to NAD
Authors: Atkinson W H , Winkler H H
Published: December 2016

Rickettsia prowazekii accumulated radioactivity from [adenine-2,8-3H]NAD but not from [nicotinamide-4-3H]NAD, which demonstrated that NAD was not taken up intact. Extracellular NAD was hydrolyzed by rickettsiae with the products of hydrolysis, nicotinamide mononucleotide and AMP, appearing in the incubation medium in a time- and temperature-dependent manner. The particulate (membrane) fraction contained 90% of this NAD pyrophosphatase activity. Rickettsiae which had accumulated radiolabel after incubation with [adenine-2,8-3H]NAD were extracted, and the intracellular composition was analyzed by chromatography. The cells contained labeled AMP, ADP, ATP, and NAD. The NAD-derived intracellular AMP was transported via a pathway distinct from and in addition to the previously described AMP translocase. Exogenous AMP (1 mM) inhibited uptake of radioactivity from [adenine-2,8-3H]NAD and hydrolysis of extracellular NAD. AMP increased the percentage of intracellular radiolabel present as NAD. Nicotinamide mononucleotide was not taken up by the rickettsiae, did not inhibit hydrolysis of extracellular NAD, and was not a good inhibitor of the uptake of radiolabel from [adenine-2,8-3H]NAD. Neither AMP nor ATP (both of which are transported) could support the synthesis of intracellular NAD. The presence of intracellular [adenine-2,8-3H]NAD within an organism in which intact NAD could not be transported suggested the resynthesis from AMP of [adenine-2,8-3H]NAD at the locus of NAD hydrolysis and translocation.
Cloning, sequencing, and characterization of the principal acid phosphatase, the phoC+ product, from Zymomonas mobilis
Authors: Pond J L , Eddy C K , Mackenzie K F , Conway T , Borecky D J , Ingram L O
Published: December 2016

The Zymomonas mobilis gene encoding acid phosphatase, phoC, has been cloned and sequenced. The gene spans 792 base pairs and encodes an Mr 28,988 polypeptide. This protein was identified as the principal acid phosphatase activity in Z. mobilis by using zymograms and was more active with magnesium ions than with zinc ions. Its promoter region was similar to the -35 "pho box" region of the Escherichia coli pho genes as well as the regulatory sequences for Saccharomyces cerevisiae acid phosphatase (PHO5). A comparison of the gene structure of phoC with that of highly expressed Z. mobilis genes revealed that promoters for all genes were similar in degree of conservation of spacing and identity with the proposed Z. mobilis consensus sequence in the -10 region. The phoC gene contained a 5' transcribed terminus which was AT rich, a weak ribosome-binding site, and less biased codon usage than the highly expressed Z. mobilis genes.
Nucleotide sequence and transcriptional organization of the Escherichia coli enterobactin biosynthesis cistrons entB and entA
Authors: Nahlik M S , Brickman T J , Ozenberger B A , McIntosh M A
Published: December 2016

The nucleotide sequence of a 2,137-base-pair DNA fragment expressing enterobactin biosynthesis functions defined the molecular boundaries and translational products of the entB and entA genes and identified a closely linked downstream open reading frame encoding an uncharacterized protein of approximately 15,000 daltons (P15). The sequence revealed that an independent protein-coding sequence corresponding to an EntG polypeptide was not situated in the genetic region between the entB and entA cistrons, to which the EntG- phonotype had been genetically localized. As a result, the biochemical nature of the EntG function in the biosynthetic pathway requires reevaluation. The EntA polypeptide displayed significant similarities at the amino acid level to the pyridine nucleotide-binding domains of several members of a family of alcohol-polyol-sugar dehydrogenase enzymes, consistent with its function as the enzyme catalyzing the final step of dihydroxybenzoate biosynthesis. An additional role for EntA in the isochorismate synthetase activity of EntC was strongly implicated by genetic evidence. Evidence from the nucleotide sequence of this region and newly constructed ent-lacZ fusion plasmids argues strongly that these genes are linked in an iron-regulated entCEBA (P15) polycistronic operon.
Plasmid-mediated production of the phytotoxin coronatine in Pseudomonas syringae pv. tomato
Authors: Bender C L , Malvick D K , Mitchell R E
Published: December 2016

Pseudomonas syringae pv. tomato PT23.2 produces the chlorosis-inducing phytotoxin coronatine. Thirty-eight chlorosis-defective mutants of PT23.2 were previously generated by using the transposon Tn5. Five mutants contained Tn5 insertions in the indigenous plasmid pPT23A; the remaining 33 mutants either were missing pPT23A (29 mutants) or contained deletions in this plasmid (4 mutants). These results suggested that pPT23A was involved in coronatine production in strain PT23.2. This plasmid was introduced into P. syringae pv. syringae PS61, which does not produce coronatine. A bioassay for coronatine suggested that PS61(pPT23A) transconjugants were able to make this phytotoxin. In a chemical analysis, organic acids were isolated from PT23.2, PS61, and the transconjugant PS61(pPT23A); these were derivatized to their methyl esters and analyzed by gas chromatography. The derivatized organic acids extracted from PT23.2 and PS61(pPT23A) contained peaks that corresponded to coronafacic acid, coronafacoylvaline, and coronatine, but these were absent in the extracts from the wild-type strain PS61. The identification of these components was confirmed by combined gas chromatography-mass spectrophotometry. Therefore, the acquisition of pPT23A by PS61 resulted in biosynthesis of coronafacic acid, coronafacoylvaline, and coronatine, clearly demonstrating the involvement of pPT23A in coronatine production in P. syringae pv. tomato.
Randomly induced Escherichia coli K-12 Tn5 insertion mutants defective in hydrogenase activity
Authors: Stoker K , Oltmann L F , Stouthamer A H
Published: December 2016

Systematic screening of 6.10(4) independent Tn5 insertion mutants of Escherichia coli yielded one new hydrogenase locus, hydF, mapping near 64.8 min, i.e., close to the hydL locus (K. Stoker, L.F. Oltmann, and A.H. Stouthamer, J. Bacteriol. 170:1220-1226, 1988). It regulated specifically the activity of the hydrogenase isoenzymes, formate dehydrogenase and lyase activities being unaffected. In hydF mutants, hydrogenase 1 and 2 activities were reduced to 1% of the parental level, whereas the electrophoretically labile part was present at about 20% of the parental level. H2 uptake was also reduced to about 20%, which suggested a relationship between these two activities. Experiments with 63Ni indicated that hydrogenase isoenzymes 1 and 2 might be present in these strains but in an inactive form. The hydF product might therefore be a posttranslational activator. At least three other mutant classes were isolated. Additional data were obtained on coisolated, nickel-restorable hydC mutants (L.F. Wu and M.-A. Mandrand-Berthelot, Biochimie 68:167-179, 1986). These strains were found to suffer a general impairment of nickel uptake. Restoration of hydrogenase activities was specific for NiCl2 and inhibited by chloramphenicol, which indicated an effect either on the transcription of hydrogenase(-associated) genes or by cotranslational incorporation in nickel-containing enzymes (e.g., in hydrogenases). The hydC mutation could not be complemented in trans, evidence that the hydC product is not a nickel transport protein but rather a cis-acting regulatory gene. Parent HB101, hydF mutants, and the other mutants were further analyzed by monitoring the induction of hydrogenase and hydrogenase-associated activities upon transition of cells from aerobic to anaerobic growth. These experiments also revealed a correlation between the early-induced H2 uptake route and labile hydrogenase activity. The formate hydrogenlyase induction patterns followed quite well the slower induction patterns of hydrogenases 1 and 2.
Molecular characterization of phycobilisome regulatory mutants of Fremyella diplosiphon
Authors: Bruns B U , Briggs W R , Grossman A R
Published: December 2016

Three classes of pigment mutants were generated in Fremyella diplosiphon in the course of electroporation experiments. The red mutant class had high levels of phycoerythrin in both red and green light and no inducible phycocyanin in red light. Thus, this mutant behaved as if it were always in green light, regardless of light conditions. Blue mutants exhibited normal phycoerythrin photoregulation, whereas the inducible phycocyanin was present at high levels in both red- and green-light-grown cells. Furthermore, the absolute amount of allophycocyanin was increased threefold in comparison with our wild-type strain. Green mutants lost the capacity to accumulate phycoerythrin in green light but showed normal photoregulation of phycocyanin. Analyses of transcript abundance in these mutants demonstrated that changes in the levels of the different phycobilisome components correlated with changes in the levels of mRNAs encoding those components. The characterization of these mutants supports hypotheses previously discussed concerning molecular mechanisms involved in the regulation of the phycobiliprotein gene sets during chromatic adaptation.
Salinity-stress-induced proteins in two nitrogen-fixing Anabaena strains differentially tolerant to salt
Authors: Apte S K , Bhagwat A A
Published: December 2016

Salinity altered the protein synthesis patterns in two cyanobacterial strains: Anabaena torulosa, a salt-tolerant brackish water strain, and Anabaena sp. strain L-31, a salt-sensitive freshwater strain. The cyanobacterial response to salinity was very rapid, varied with time, and was found to be correlated with the external salt (NaCl) concentration during stress. Salinity induced three prominent types of modification. First, the synthesis of several proteins was inhibited, especially in the salt-sensitive strain; second, the synthesis of certain proteins was significantly enhanced; and third, synthesis of a specific set of proteins was induced de novo by salinity stress. Proteins which were selectively synthesized or induced de novo during salt stress, tentatively called the salt-stress proteins, were confined to an isoelectric pI range of 5.8 to 7.5 and were distributed in a molecular mass range of 12 to 155 kilodaltons. These salt-stress proteins were unique to each Anabaena strain, and their expression was apparently regulated coordinately during exposure to salt stress. In Anabaena sp. strain L-31, most of the salt-stress-induced proteins were transient in nature and were located mainly in the cytoplasm. In A. torulosa, salt-stress-induced proteins were evenly distributed in the membrane and cytoplasmic fractions and were persistent, being synthesized at high rates throughout the period of salinity stress. These initial studies reveal that salinity-induced modification of protein synthesis, as has been demonstrated in higher plant species, also occurs in cyanobacteria and that at least some of the proteins preferentially synthesized during salt stress may be important to cyanobacterial osmotic adaptation.