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1.
Article in English | MEDLINE | ID: mdl-37506005

ABSTRACT

Software programming is an acquired evolutionary skill originating from consolidated cognitive functions (i.e., attentive, logical, coordination, mathematic calculation, and language comprehension), but the underlying neurophysiological processes are still not completely known. In the present study, we investigated and compared the brain activities supporting realistic programming, text and code reading tasks, analyzing Electroencephalographic (EEG) signals acquired from 11 experienced programmers. Multichannel spectral analysis and a phase-based effective connectivity study were carried out. Our results highlighted that both realistic programming and reading tasks are supported by modulations of the Theta fronto-parietal network, in which parietal areas behave as sources of information, while frontal areas behave as receivers. Nevertheless, during realistic programming, both an increase in Theta power and changes in network topology emerged, suggesting a task-related adaptation of the supporting network system. This reorganization mainly regarded the parietal area, which assumes a prominent role, increasing its hub functioning and its connectivity in the network in terms of centrality and degree.


Subject(s)
Brain , Electroencephalography , Humans , Brain/physiology , Electroencephalography/methods , Cognition , Attention/physiology , Software , Brain Mapping/methods
2.
Annu Int Conf IEEE Eng Med Biol Soc ; 2019: 1413-1416, 2019 Jul.
Article in English | MEDLINE | ID: mdl-31946157

ABSTRACT

This paper provides a study using Electroencephalography (EEG) to investigate the brain activity during code comprehension tasks. Three different code complexity levels according to five complexity metrics were considered. The use of EEG for this purpose is relevant, since the existing studies were mostly focused on neuroimaging techniques. Using Leave-One-Subject-Out cross-validation procedure for 30 subjects, it was found that the features related with the Gamma activity were the most common in all the folds. Regarding the brain regions, right parietal was the most frequent region contributing with more features. A Linear Discriminant Analysis Classifier for task classification, obtained a F-Measure of 92.71% for Code complexity easy, 52.25% for Code complexity intermediate and 53.13% for Code complexity advanced, revealing an evidence of mental effort saturation with the code complexity degree. This suggests that current code complexity metrics do not capture cognitive load and might not be the best approach to assess bug risk.


Subject(s)
Brain , Electroencephalography , Software , Comprehension , Neuroimaging
3.
Genet Mol Res ; 14(3): 10139-44, 2015 Aug 21.
Article in English | MEDLINE | ID: mdl-26345950

ABSTRACT

The purpose of the present study was to functionally evaluate the influence of superoxide radical-generating compounds on the heterologous induction of a predicted promoter region of open reading frames for paraquat-inducible genes (pqi genes) revealed during genome annotation analyses of the Chromobacterium violaceum bacterium. A 388-bp fragment corresponding to a pqi gene promoter of C. violaceum was amplified using specific primers and cloned into a conjugative vector containing the Escherichia coli lacZ gene without a promoter. Assessments of the expression of the ß-galactosidase enzyme were performed in the presence of menadione (MEN) and phenazine methosulfate (PMS) compounds at different final concentrations to evaluate the heterologous activation of the predicted promoter region of interest in C. violaceum induced by these substrates. Under these experimental conditions, the MEN reagent promoted highly significant increases in the expression of the ß-galactosidase enzyme modulated by activating the promoter region of the pqi genes at all concentrations tested. On the other hand, significantly higher levels in the expression of the ß-galactosidase enzyme were detected exclusively in the presence of the PMS reagent at a final concentration of 50 µg/mL. The findings described in the present study demonstrate that superoxide radical-generating compounds can activate a predicted promoter DNA motif for pqi genes of the C. violaceum bacterium in a dose-dependent manner.


Subject(s)
Chromobacterium/genetics , Gene Expression Regulation, Bacterial/drug effects , Genes, Bacterial , Paraquat/toxicity , Promoter Regions, Genetic , Superoxides/metabolism , Chromobacterium/drug effects , beta-Galactosidase/metabolism
5.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 5): o1106, 2010 Apr 17.
Article in English | MEDLINE | ID: mdl-21579158

ABSTRACT

The title compound, C(12)H(16)N(2)O(2)S, was synthesized from furoyl isothio-cyanate and cyclo-hexyl-amine in dry acetone, and the crystal structure redetermined. The thio-urea group is in the thio-amide form. The structure [Otazo-Sánchez et al. (2001 ▶). J. Chem. Soc. Perkin Trans. 2, pp. 2211-2218] has been redetermined in order to establish the intra- and inter-molecular inter-actions. The trans-cis geometry of the thio-urea group is stabilized by intra-molecular hydrogen bonding between the carbonyl and cis-thio-amide groups, resulting in a pseudo-S(6) planar ring which makes a dihedral angle of 3.24 (6)° with the 2-furoyl group and a torsion angle of -84.3 (2)° with the cyclo-hexyl group. There is also an intra-molecular hydrogen bond between the furan O atom and the other thio-amide H atom. In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯O hydrogen bonds, forming chains along [010].

6.
Anim Genet ; 39(6): 659-61, 2008 Dec.
Article in English | MEDLINE | ID: mdl-18752582

ABSTRACT

To determine the polymorphisms of the prion protein gene in sheep from the state of Paraná, Brazil, 323 animals of meat breeds (Suffolk, Hampshire Down, Texel, Ile de France, Dorper, Dorset, Santa Inês and crossbreds) were genotyped by restriction fragment length polymorphism (RFLP) analysis. The most frequent allele was ARQ, with a frequency of 0.61, followed by ARR (0.30). VRQ and AHQ alleles were present at very low frequencies (0.13 and 0.05 respectively), and the ARH allele was not found. Seven genotypes were identified (ARR/ARR, ARR/ARQ, ARQ/ARQ, ARR/VRQ, ARR/AHQ, ARQ/VRQ and ARQ/AHQ), of which ARQ/ARQ was the most frequent (0.41). The Santa Inês breed and crossbred animals showed the highest genotypic variability.


Subject(s)
Polymorphism, Genetic , Prions/genetics , Sheep/genetics , Animals , Brazil , Genotype , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length
7.
J Colloid Interface Sci ; 322(2): 527-36, 2008 Jun 15.
Article in English | MEDLINE | ID: mdl-18440546

ABSTRACT

Adsorption methods have been developed for the removal of arsenic from solution motivated by the adverse health effects of this naturally occurring element. Iron exchanged natural zeolites are promising materials for this application. In this study we introduced iron species into a clinoptilolite-rich zeolitic tuff by the liquid exchange method using different organic and inorganic iron salts after pretreatment with NaCl and quantified the iron content in all trials by XRF spectroscopy. The materials were characterized by XRD, FTIR, FTIR-DR, UV-vis, cyclic voltammetry, ESR and Mössbauer spectroscopies before and after adsorption of arsenite and arsenate. The reached iron load in the sample T+Fe was %Fe(2)O(3)-2.462, n(Fe)/n(Al)=0.19, n(Si)/n(Fe)=30.9 using FeCl(3), whereby the iron leachability was 0.1-0.2%. The introduced iron corresponded to four coordinated species with tetrahedral geometry, primarily low spin ferric iron adsorbing almost 12 mug g(-1) arsenite (99% removal) from a 360 mug(As(III)) L(-1) and 6 mug g(-1) arsenate from a 230 mug(As(V)) L(-1). Adsorption of arsenite and arsenate reached practically a plateau at n(Fe)/n(Si)=0.1 in the series of exchanged tuffs. The oxidation of arsenite to arsenate in the solution in contact with iron modified tuff during adsorption was observed by speciation. The reduction of ferric iron to ferrous iron could be detected in the electrochemical system comprising an iron-clinoptilolite impregnated electrode and was not observed in the dried tuff after adsorption.

8.
Acta Reumatol Port ; 32(4): 351-61, 2007.
Article in Portuguese | MEDLINE | ID: mdl-18159202

ABSTRACT

INTRODUCTION: Rheumatic patients with chronic pain describe in a vivid way the influence of climate on pain and disease activity. Several studies seem to confirm this association. OBJECTIVES: To evaluate and compare in a population of rheumatic patients the perceived influence of weather changes on pain and disease activity METHODS: This is a retrospective cross-sectional study. For three weeks an assisted self-reported questionnaire with nine dimensions and a VAS pain scale was performed on consecutive out-patients in our clinic. RESULTS: 955 patients 787 female 168 male mean age 57.9 years with several rheumatologic diagnosis were evaluated. Overall 70 of the patients believed that the weather influenced their disease and 40 believed that the influence was high. Morning stiffness was influenced in 54 high influenced in 34 . Autumn and Winter were the most influential periods as well as humidity 67 and low temperatures 59 . CONCLUSION: In our study as well as in literature we found that a high percentage of patients 70 perceived that weather conditions influenced their pain and disease. Fibromyalgia patients seemed to be strongly influenced by weather changes. Our study confirms that patients perception on the influence of climate on pain and therefore their disease is an important clinical factor and it should be considered when evaluating rheumatic patients.


Subject(s)
Pain/etiology , Rheumatic Diseases/complications , Weather , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Retrospective Studies
9.
J Anim Breed Genet ; 123(5): 326-30, 2006 Oct.
Article in English | MEDLINE | ID: mdl-16965405

ABSTRACT

Different alleles of the human and ovine prion protein gene correlate with a varying susceptibility to transmissible spongiform encephalopathies. However, the pathogenic implications of specific polymorphisms in the bovine prion protein gene (PRNP) are only poorly understood. Previous studies on the bovine PRNP gene investigated common European and North American cattle breeds. As a consequence of decades of intensive breeding for specific traits, these modern breeds represent only a small fraction of the bovine gene pool. In this study, we analysed PRNP polymorphisms in the native Brazilian Caracu breed, which developed in geographical isolation since the 16th century. A total of 10 single nucleotide polymorphisms (SNPs) were discovered in the coding region of the Caracu PRNP gene. Eight of the SNPs occurred at high frequencies in Caracu cattle (variant allele frequencies = 0.10-0.76), but were absent or only rarely observed in European and North American breeds. One of the Caracu SNPs was associated with an amino acid exchange from serine to asparagine (f = 0.17). This SNP was not detected in Holstein-Friesian, Simmental and German Gelbvieh and was only rarely detected in beef cattle (f = 0.01). We found 17 haplotypes for PRNP in the Caracu breed.


Subject(s)
Cattle/genetics , Polymorphism, Single Nucleotide , Prions/genetics , Animals , Brazil , Gene Frequency , Haplotypes , Mutation, Missense , Polymerase Chain Reaction , Sequence Analysis, Protein
11.
Nanotechnology ; 17(10): 2528-35, 2006 May 28.
Article in English | MEDLINE | ID: mdl-21727500

ABSTRACT

Co(3)O(4) nanoparticles have been produced by mechanochemical reactions involving cobalt carbonate, sodium oxide and sodium carbonate. The mechanochemical reactions are carried out during milling at room temperature and the nanoparticles have been obtained without the need for any thermal treatment after the milling operation. The CoO phase is produced in the first 30 min of the mechanochemical process, followed by a second stage of oxidation to Co(3)O(4) which lasts for several hours. Under proper milling conditions the final products were soft agglomerates of ultrafine particles with average sizes between 15 and 20 nm.

12.
Eur Heart J ; 24(5): 442-63, 2003 Mar.
Article in English | MEDLINE | ID: mdl-12633546

ABSTRACT

BACKGROUND: The European Society of Cardiology (ESC) has published guidelines for the investigation of patients with suspected heart failure and, if the diagnosis is proven, their subsequent management. Hospitalisation provides a key point of care at which time diagnosis and treatment may be refined to improve outcome for a group of patients with a high morbidity and mortality. However, little international data exists to describe the features and management of such patients. Accordingly, the EuroHeart Failure survey was conducted to ascertain if appropriate tests were being performed with which to confirm or refute a diagnosis of heart failure and how this influenced subsequent management. METHODS: The survey screened consecutive deaths and discharges during 2000-2001 predominantly from medical wards over a 6-week period in 115 hospitals from 24 countries belonging to the ESC, to identify patients with known or suspected heart failure. RESULTS: A total of 46788 deaths and discharges were screened from which 11327 (24%) patients were enrolled with suspected or confirmed heart failure. Forty-seven percent of those enrolled were women. Fifty-one percent of women and 30% of men were aged >75 years. Eighty-three percent of patients had a diagnosis of heart failure made on or prior to the index admission. Heart failure was the principal reason for admission in 40%. The great majority of patients (>90%) had had an ECG, chest X-ray, haemoglobin and electrolytes measured as recommended in ESC guidelines, but only 66% had ever had an echocardiogram. Left ventricular ejection fraction had been measured in 57% of men and 41% of women, usually by echocardiography (84%) and was <40% in 51% of men but only in 28% of women. Forty-five percent of women and 22% of men were reported to have normal left ventricular systolic function by qualitative echocardiographic assessment. A substantial proportion of patients had alternative explanations for heart failure other than left ventricular systolic or diastolic dysfunction, including valve disease. Within 12 weeks of discharge, 24% of patients had been readmitted. A total of 1408 of 10434 (13.5%) patients died between admission and 12 weeks follow-up. CONCLUSIONS: Known or suspected heart failure comprises a large proportion of admissions to medical wards and such patients are at high risk of early readmission and death. Many of the basic investigations recommended by the ESC were usually carried out, although it is not clear whether this was by design or part of a general routine for all patients being admitted regardless of diagnosis. The investigation most specific for patients with suspected heart failure (echocardiography) was performed less frequently, suggesting that the diagnosis of heart failure is still relatively neglected. Most men but a minority of women who underwent investigation of cardiac function had evidence of moderate or severe left ventricular dysfunction, the main target of current advances in the treatment of heart failure. Considerable diagnostic uncertainty remains for many patients with suspected heart failure, even after echocardiography, which must be resolved in order to target existing and new therapies and services effectively.


Subject(s)
Cardiac Output, Low/therapy , Hospitalization/statistics & numerical data , Quality of Health Care , Aged , Cardiac Output, Low/complications , Cardiac Output, Low/mortality , Cardiovascular Diseases/complications , Cardiovascular Diseases/therapy , Europe/epidemiology , Female , Health Surveys , Hospital Mortality , Humans , Male , Middle Aged , Multivariate Analysis , Patient Readmission , Practice Guidelines as Topic , Risk Factors , Survival Analysis
13.
Eur Heart J ; 24(5): 464-74, 2003 Mar.
Article in English | MEDLINE | ID: mdl-12633547

ABSTRACT

BACKGROUND: National surveys suggest that treatment of heart failure in daily practice differs from guidelines and is characterized by underuse of recommended medications. Accordingly, the Euro Heart Failure Survey was conducted to ascertain how patients hospitalized for heart failure are managed in Europe and if national variations occur in the treatment of this condition. METHODS: The survey screened discharge summaries of 11304 patients over a 6-week period in 115 hospitals from 24 countries belonging to the ESC to study their medical treatment. RESULTS: Diuretics (mainly loop diuretics) were prescribed in 86.9% followed by ACE inhibitors (61.8%), beta-blockers (36.9%), cardiac glycosides (35.7%), nitrates (32.1%), calcium channel blockers (21.2%) and spironolactone (20.5%). 44.6% of the population used four or more different drugs. Only 17.2% were under the combination of diuretic, ACE inhibitors and beta-blockers. Important local variations were found in the rate of prescription of ACE inhibitors and particularly beta-blockers. Daily dosage of ACE inhibitors and particularly of beta-blockers was on average below the recommended target dose. Modelling-analysis of the prescription of treatments indicated that the aetiology of heart failure, age, co-morbid factors and type of hospital ward influenced the rate of prescription. Age <70 years, male gender and ischaemic aetiology were associated with an increased odds ratio for receiving an ACE inhibitor. Prescription of ACE inhibitors was also greater in diabetic patients and in patients with low ejection fraction (<40%) and lower in patients with renal dysfunction. The odds ratio for receiving a beta-blocker was reduced in patients >70 years, in patients with respiratory disease and increased in cardiology wards, in ischaemic heart failure and in male subjects. Prescription of cardiac glycosides was significantly increased in patients with supraventricular tachycardia/atrial fibrillation. Finally, the rate of prescription of antithrombotic agents was increased in the presence of supraventricular arrhythmia, ischaemic heart disease, male subjects but was decreased in patients over 70. CONCLUSION: Our results suggest that the prescription of recommended medications including ACE inhibitors and beta-blockers remains limited and that the daily dosage remains low, particularly for beta-blockers. The survey also identifies several important factors including age, gender, type of hospital ward, co morbid factors which influence the prescription of heart failure medication at discharge.


Subject(s)
Cardiac Output, Low/drug therapy , Cardiovascular Agents/therapeutic use , Quality of Health Care , Adrenergic beta-Antagonists/therapeutic use , Age Factors , Aged , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Aspirin/therapeutic use , Calcium Channel Blockers/therapeutic use , Cardiac Glycosides/therapeutic use , Cardiac Output, Low/complications , Europe , Female , Fibrinolytic Agents/therapeutic use , Health Surveys , Hospitalization , Humans , Male , Multivariate Analysis , Platelet Aggregation Inhibitors/therapeutic use , Spironolactone/therapeutic use
14.
Lancet ; 360(9346): 1631-9, 2002 Nov 23.
Article in English | MEDLINE | ID: mdl-12457785

ABSTRACT

BACKGROUND: Heart failure is a prevalent condition that is generally treated in primary care. The aim of this study was to assess how primary-care physicians think that heart failure should be managed, how they implement their knowledge, and whether differences exist in practice between countries. METHODS: The survey was undertaken in 15 countries that had membership of the European Society of Cardiology (ESC) between Sept 1, 1999, and May 31, 2000. Primary-care physicians' knowledge and perceptions about the management of heart failure were assessed with a perception survey and how a representative sample of patients was managed with an actual practice survey. FINDINGS: 1363 physicians provided data for 11062 patients, of whom 54% were older than 70 years and 45% were women. 82% of patients had had an echocardiogram but only 51% of these showed left ventricular systolic dysfunction. Ischaemic heart disease, hypertension, diabetes mellitus, atrial fibrillation, and major valve disease were all common. Physicians gave roughly equal priority to improvement of symptoms and prognosis. Most were aware of the benefits of ACE inhibitors and beta blockers. 60% of patients were prescribed ACE inhibitors, 34% beta blockers but only 20% received these drugs in combination. Doses given were about 50% of targets suggested in the ESC guidelines. If systolic dysfunction was documented, ACE inhibitors were more likely and beta blockers less likely to be prescribed than when there was no evidence of systolic dysfunction. INTERPRETATION: Results from this survey suggest that most patients with heart failure are appropriately investigated, although this finding might be as a result of high rates of hospital admissions. However, treatment seems to be less than optimum, and there are substantial variations in practice between countries. The inconsistencies between physicians' knowledge and the treatment that they deliver suggests that improved organisation of care for heart failure is required.


Subject(s)
Cardiotonic Agents/therapeutic use , Heart Failure/drug therapy , Practice Patterns, Physicians' , Primary Health Care/methods , Aged , Attitude of Health Personnel , Data Collection , Europe/epidemiology , Female , Heart Failure/epidemiology , Heart Failure/mortality , Humans , Male
15.
Rev Port Cardiol ; 20(12): 1259-66, 2001 Dec.
Article in English, Portuguese | MEDLINE | ID: mdl-11865686

ABSTRACT

The management of heart failure in Europe is largely conducted by primary care physicians in out-patient clinics and by cardiologists and internists in hospitals. Several reports suggest differences among these specialists regarding knowledge and actual practice, and indicate that the application of guidelines is far from optimal. In order to look for differences between cardiologists and internists in terms of implementation of guidelines a survey was carried out among the directors of 83 hospital departments of cardiology and internal medicine in Portugal. The survey included questions about diagnostic and treatment protocols, special areas for management, and suggestions to improve the quality of heart failure patient treatment. The answers suggest that in Portuguese hospitals at least half of the patients with HF are treated by internists. Treatment protocols exist in about 25% of the cardiology departments but are virtually non-existent in internal medicine. The use and availability of echocardiography are high in cardiology but no more than reasonable in internal medicine. There are neither special in-hospital areas nor specialized nurses for the treatment of HF. Cardiologists recognize the need for greater specialization in this field--doctors, nurses and clinics--but this is not a priority for internists. An effort should be made to improve in-hospital HF treatment.


Subject(s)
Heart Failure/diagnosis , Heart Failure/therapy , Practice Patterns, Physicians' , Cardiology , Health Care Surveys , Hospitals , Humans , Internal Medicine , Portugal
16.
Eur J Heart Fail ; 2(2): 123-32, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10856724

ABSTRACT

BACKGROUND: The EUROHEART programme is a rolling programme of cardiovascular surveys among the member nations of the European Society of Cardiology (ESC). These surveys will provide information on the nature of cardiovascular disease and its management. This manuscript describes a survey into the nature and management of heart failure. AIMS: The EuroHeart Failure survey aims to describe the quality of hospital care, diagnostic and therapeutic, for patients with suspected or confirmed heart failure in ESC member countries. Patients will be interviewed subsequent to hospital discharge to assess their understanding of their condition, side effects from and their compliance with therapy and their satisfaction with the management for heart failure. The quality of management will be judged against the recommendations contained in the ESC guidelines on diagnosis and treatment of heart failure. Outcome will be further assessed by repeat interviews in 6-12 months time. A further survey of heart failure in 2001/2002 is also planned. METHODS: A prospective survey of all deaths and discharges from medical (cardiology, internal medicine and geriatric medicine) and cardiac surgical wards to identify patients with heart failure, suspected or confirmed. Approximately 70 hospital clusters, comprising two to six hospitals in each cluster, in 24 member countries of the ESC are conducting the study. At the time of writing, approximately 30000 deaths and discharges have been screened and approximately 4000 patients have been enrolled. CONCLUSIONS: The EuroHeart Survey will allow actual practice to be compared to ESC guidelines on the diagnosis and treatment of heart failure. The surveys and guidelines should prove mutually informative. The main EuroHeart Failure project will be completed by late 2000. However, new centres volunteering to participate in the study (contact corresponding author) may be accepted providing they have the necessary research personnel and provided funding can be agreed for statistical support and administration.


Subject(s)
Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Health Surveys , Heart Failure/therapy , Quality of Health Care , Europe , Heart Failure/complications , Heart Failure/diagnosis , Humans , Practice Guidelines as Topic , Prospective Studies , Ventricular Dysfunction, Left/complications , Ventricular Dysfunction, Left/drug therapy
18.
FEMS Microbiol Lett ; 150(1): 81-8, 1997 May 01.
Article in English | MEDLINE | ID: mdl-9163910

ABSTRACT

Growth of Prevotella ruminicola strains B(1)4 (subsp. brevis) and D31d (subsp. ruminicola), was inhibited by protamine, a polycationic, low molecular mass protein. Results showed that protamine has a bacteriocidal effect when present in concentrations exceeding 30 micrograms ml-1. Protamine exerted its toxic effects by disrupting the outer membrane, which was demonstrated by: (i) an increased sensitivity to hydrophobic antibiotics (novobiocin and monensin) and (ii) release of the periplasmic enzyme alkaline phosphatase following short-term exposure to protamine. Although the concentrations of protamine inhibitory to P. ruminicola are relatively low, the effects of such a compound are probably too broad to permit its successful use in terms of manipulating ruminal proteolysis.


Subject(s)
Anti-Bacterial Agents/pharmacology , Prevotella/drug effects , Protamines/pharmacology , Alkaline Phosphatase/metabolism , Cell Membrane/drug effects , Microbial Sensitivity Tests , Monensin/pharmacology , Novobiocin/pharmacology , Prevotella/growth & development
19.
Appl Environ Microbiol ; 63(2): 670-5, 1997 Feb.
Article in English | MEDLINE | ID: mdl-9023945

ABSTRACT

A chemical mutagenesis protocol was used with the ruminal bacterium Prevotella ruminicola strain B(1)4 to generate mutant strains defective in peptidase activity. Compared with the wild-type parent strain, the isolated mutants possessed 1/10 of the enzyme activity responsible for cleavage of glycine-arginine-4-methoxy-beta-naphthylamide (Gly-Arg-MNA). A concomitant loss in activity against arginine-arginine-4-methoxy-beta-naphthylamide (Arg-Arg-MNA) was also observed. Both activities were similarly affected by various proteinase inhibitors, suggesting that the same enzyme is responsible for the Arg-Arg-MNA peptidase and Gly-Arg-MNA peptidase activities. Growth rates of wild-type and mutant strains grown in batch culture with various nitrogen sources did not differ. However, a role for the Gly-Arg-MNA peptidase activity was demonstrated in coculture experiments with gram-positive, ammonia-producing ruminal bacteria. The rate and extent of ammonia production were reduced by approximately 25% in cocultures containing the mutants when compared with that of wild-type-containing cultures. These reductions could not be accounted for simply by the decrease in ammonia production by the mutant strain alone. To our knowledge, this paper reports the first successful use of chemical mutagenesis with ruminal microorganisms.


Subject(s)
Ammonia/metabolism , Cysteine Endopeptidases/metabolism , Hemagglutinins/metabolism , Mutagenesis , Prevotella/enzymology , Rumen/microbiology , 2-Naphthylamine/analogs & derivatives , 2-Naphthylamine/metabolism , Adhesins, Bacterial , Animals , Cysteine Endopeptidases/genetics , Dipeptides/metabolism , Gingipain Cysteine Endopeptidases , Hemagglutinins/genetics , Prevotella/genetics , Prevotella/growth & development , Subcellular Fractions/enzymology
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