Correlations of the Peculiarities of the Motivational Sphere and Characteristics of Event-Related EEG Potentials in Humans

We studied the relations between generalized characteristics of the state of the motivational sphere, the levels of need for achievements (N-Ach) and achievement motivation (AchM) typical of an individual, and the parameters of cerebral event-related potentials (ERPs). The examined group included 70 adults of both sexes. The ERPs were recorded in the course of realization of two behavioral test acts with motor components. In task А, the subject should press a button with the minimum delay with respect to an imperative signal preceded by a warning signal (with the measurement of the time of sensorimotor reaction); in this case, the contingent negative variation (CNV) and Р300 potential were recorded. Under conditions of task B, the subject should measure a definite time interval limiting the latter by two pushings of the button; in this case, the readiness potential (RP) was recorded in addition to CNV and Р300. The ERPs were recorded in the С3 and С4 leads (according to the 10-20 system). The peculiarities of the motivational sphere were diagnosed using Orlov’s and Mechrabian’s questionnaires. We found that a relatively high amplitude of the early CNV component (СNV-O) and low amplitudes of the integral CNV and Р300 in task A and a low amplitude of the RP can serve as task B-related EEG markers of a high NA level. In task A, high levels of the AchM correlated with higher amplitudes of the CNV and Р300, and amplitudes of these potentials were higher in the left hemisphere. The observed interrelations were probably determined by a considerable dependence of the N-Ach and AchM characteristics, on the one hand, and CNV amplitude parameters, on the other hand, on the hereditary factors, in particular neurochemical ones. It is obvious that such peculiarities of the neurodynamic constitution of an individual are, to a considerable extent, determined by the specificity of organization and functioning of a few neurotransmitter (in particular aminergic) and neurohumoral systems.     

Correlations between the level of aggressiveness of personality and characteristics of event-related EEG potentials

In a group of 76 adults of both sexes, we examined interrelations between the level of aggressiveness of the individual (diagnosed using the Buss-Durkee Hostility Inventory) and parameters of event-related EEG potentials (ERPs) recorded under conditions of two behavioral test acts including a motor component. Within the framework of task A, the subject must push a button with the shortest delay after an executory signal preceded by a warning signal; the time of sensorimotor reaction was measured. Under these conditions, we recorded the contingent negative variayion (CNV) and the P300 potential. In the case of task B, it was necessary to measure a definite time interval limited by two pushings of the button. Under these conditions, the readiness potential (RP) was recorded in addition to the CNV and P300. The C3 and C4 leads were used (according to the 10–20 system); the time constant of an amplification tract was 10 sec. Despite natural broad interindividual variability, high amplitudes of the recorded ERPs (RP, CNV, and P300) in general corresponded to lower indices by scales of the Buss-Durkee inventory and smaller values of the indices of aggressiveness and hostility. These interrelations are, probably, based on the fact that both characteristics of aggressiveness of the personality and EEG amplitude parameters are to a considerable extent determined by hereditary factors. It is believed that the respective peculiarities of the neurodynamic constitution of the individual are to a great extent dependent on the specificities of organization and functioning of a few neurotransmitter (in particular, aminergic) and neurohumoral systems. Neirofiziologiya/Neurophysiology, Vol. 39, No. 2, pp. 154–164, March–April, 2007.     

Locus of Psychological Control and Peculiarities of Event-Related EEG Potentials

In a group including 74 adults of both sexes, we examined interrelations between the locus of psychological control (diagnosed using the Rotter questionnaire) and parameters of event-related EEG potentials, ERPs, recorded in the course of performance of two behavioral test acts with a motor component. Task A corresponded to maximally fast pushing on the button after a signal with warning; the time of the sensorimotor reaction was measured. Task B included internal counting of a definite time interval limited by two pushings on the button. Under these conditions, we recorded the contingent negative variation (CNV), the P300 potential, and, in task B, the readiness potential (RP). EEG leads C3 and C4, according to the 10-20 system, were used. Internals (estimates by the questionnaire, 6 stens or higher) were characterized by higher amplitudes of the terminal CNV (CNV-T), integral CNV, and P300 in task A, by greater RP and CNV amplitudes in task B, and also by shorter reaction times and their smaller dispersion. It should be supposed that the corresponding peculiarities of the neurodynamic constitution of an individual are determined, to a considerable extent, by the specificity of organization and functioning of a few neurotransmitter (aminergic in particular) and neurohumoral systems.     

Psychological Adaptation Potential of the Personality: Peculiarities of Event-Related EEG Potentials

In a group of 68 adults of both sexes, we examined correlations between the level of psychological adaptability of the personality (diagnosed using the Maklakov questionnaire) and parameters of event-related potentials (ERPs) recorded in the course of performance of two behavioral test acts including a motor component. In task A, it was necessary to maximally rapidly press the button after an imperative signal preceded by a warning signal, while a definite time interval (limited by two pressings of the button) should be measured in task B. Parameters of the contingent negative variation, CNV, potential P300 and, in task B, readiness potential, RP, were measured in C3 and C4 leads. High amplitudes of ERPs (RP, P300, and CNV in task A) and smaller variability of the indices of working efficiency corresponded, in the whole, to higher estimates of psychological adaptability in general and of separate aspects of the latter estimated according to the scales of the used questionnaire. Probable mechanisms of the peculiarities of neurodynamic constitution determining the level of the psychological adaptability of the individual, on the one hand, and of the ERP parameters, on the other hand, are discussed.     

Reflection of Anxiety in the Characteristics of Evoked EEG Potentials in 10- to 11-Year-Old Children

We studied the peculiarities of the amplitude/time parameters of evoked EEG potentials (EPs) and event-related potentials (ERPs) in 10- to 11-year-old children characterized by low and high anxiety levels. The latter levels were estimated using the scale of the manifest anxiety test of Prikhozhan and projective techniques (“House–Tree–Person,” HTP, and the Lüscher color test). For children with a high anxiety level, the amplitudes of the following EP components and ERPs were lower than those in low-anxiety children of the same age: P1 (predominantly in the occipital region of the left hemisphere), P2 (in the right occipital region), and Р300 wave (in different loci of both hemispheres). In high-anxiety children, we also more frequently observed increased amplitudes of the N2 component in the left parietal and right occipital regions. High-anxiety individuals were characterized by longer latencies of component P1 (mostly in the right frontal and left central regions) and, at the same time, shorter latencies of component N1 (in the parietal and occipital regions of the left hemisphere and also in the right temporal region). Thus, we found that the amplitude/time characteristics of a few EP components and ERPs in children with high anxiety levels differ statistically significantly from the parameters of corresponding EPs/ERPs in individuals of the same age but with low anxiety levels.     

Individual personality-related characteristics of event-related EEG potentials recorded in an experimental situation requiring production of time intervals

Event-related EEG potentials (ERP) were recorded from 75 tested adult men and women; recording was performed from C3 and C4 points. The experimental situation required internal counting of time intervals limited by two pushes of a button. The experimental paradigm provided a substantial level of uncertainty, and a high level of attention needed to be maintained. The tested subjects were not informed by the experimenter about the precise value of the preset time interval; they knew only its limits, 17–23 sec. The subject obtained information about the agreement or disagreement between the produced interval and its value preset by the experimenter by visual feedback signals obtained 2 sec after termination of counting; in the case of agreement the subject had to perform a confirming (third) push of the button. Pushes were preceded by readiness potentials (RP); contingent negative variation (CNV) developed before the feedback signals, and the latter were accompanied by P300 potentials. Significant positive correlations were found between the parameters of RP and P300 in both hemispheres. In general, ERP were characterized by very high interindividual variability, which in a few respects correlated with the personality-related characteristics of tested subjects evaluated by psychological testing with the use of corresponding questionnaires. In particular, under the experimental conditions used, negative correlations were observed between the RP amplitude and psychotism indices, CNV amplitude and emotional stability; CNV amplitude and extroversive features, and P300 amplitude and domination properties of a person. Positive correlations were observed between the CNV amplitude and autia factor (according to Eysenck’s PEN and Cattell’s 16 PF questionnaires). We suppose that correlations between the personal psychical features and ERP parameters are grounded in both inherited constitutional specificities of the nervous system and neurochemical/structural modifications in the brain determined by the acquired vital experience.     

Readiness to respond in a target detection task: pre- and post-stimulus event-related potentials in normal subjects

Brain potentials were recorded from 12 normal subjects engaged in an auditory target detection task (target stimulus probability of 0.2, stimulus rate of 1 every 2 sec) when instructions were (1) to press a response button with the thumb of the dominant hand to each target or (2) to keep a mental count of each target. A pre-stimulus slow negative potential was identified before every stimulus except non-targets immediately after targets. The amplitude of the pre-stimulus negativity was significantly affected by task instructions and was up to 4 times larger during the button press than the mental count condition. In contrast, the amplitudes and latencies of the event-related components (N100, P200, N200 and P300), when slow potentials were removed by filtering, were not different as a function of press or count instructions. The immediately preceding stimulus sequence affected both the amplitude and onset latency of the pre-stimulus negativity; both measures increased as the number of preceding non-targets increased. The amplitude of the pre-stimulus negative shift to targets also increased significantly as RT speed decreased. The major portion of the pre-stimulus negative potential is considered a readiness potential (RP) reflecting preparations to make a motor response. The amplitude of the RP during the target detection task did not significantly lateralize in contrast to the RP accompanying self-paced movements.     

Wavelet entropy in event-related potentials: a new method shows ordering of EEG oscillations

 In this work we show the application of a measure of entropy defined from the wavelet transform, namely the wavelet entropy (WS), to the study of event-related potentials (ERPs). WS was computed for ERPs recorded from nine healthy subjects with three different types of stimuli, among them target stimuli in a cognitive task. A significant decrease of entropy was correlated with the responses to target stimuli (P300), thus showing that these responses correspond to a more “ordered” state than the spontaneous EEG. Furthermore, we propose the WS as a quantitative measure for such transitions between EEG (“disordered state”) and ERP (“ordered state”). Received: 12 April 2000 / Accepted in revised form: 11 September 2000     

The recovery functions of auditory event-related potentials during split-second discriminations

We examined the recovery cycles of auditory event-related potentials (ERPs) in a high-speed auditory discrimination task and in passive conditions. Each trial contained 3 tones cued by a warning flash. In passive conditions, auditory ERPs consisted mainly of N1 (108 msec) and P2 (213 msec) components superimposed on a small CNV. The N1 and P2 were comparable in amplitude and both had prolonged refractory periods. In discriminative reaction time (DRT) conditions the same tones cued or inhibited press responses and elicited additional endogenous components (principally the Nd and P3). ERPs in DRT conditions were superimposed upon a prominent CNV that began after the warning cue and lasted throughout the signal delivery period.The N1 was larger in active than passive conditions and showed less marked refractory effects, while the P2 was smaller and showed more marked refractoriness. Differences between active and passive conditions could be explained by the presence of an endogenous negative potential (the Nd) with a short refractory period that was superimposed upon the N1 and P2.The P3 was recorded only in active conditions. At short ISIs (0.5 sec), P3 amplitudes were reduced and P3 latencies lengthened in parallel with prolongations in reaction time due to so-called psychological refractory period (PRP) effects. Both P3 recovery and the PRP reflected central mechanisms since they were observed at short ISIs when stimuli cueing different responses succeeded one another.N1 and P3 amplitudes diminished over the course of the experiment in both active and passive conditions. The decrease (amounting to about 30% of initial amplitudes) did not appear due to reductions in vigilance, since it was not accompanied by changes in reaction time or response accuracy, or by changes in other endogenous components (CNV or Nd). Short-term N1 habituation was unaffected by long-term amplitude reductions suggesting that independent mechanisms were responsible for the two phenomena.     

The P300 event-related potentials in dementia of the Alzheimer type. Correlations between P300 and monoamine metabolites

We studied auditory event-related potentials (ERPs) in 40 patients with dementia of the Alzheimer type (DAT). Peak latencies and amplitudes of N100, P200 and P300 components were measured. To study the possible relationships between the ERPs and monoaminergic neurotransmitter functions, CSF neurotransmitter metabolites were also analyzed. In patients with DAT, the P300 amplitude was significantly reduced and the P300 latency was prolonged. CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) were decreased. The P300 amplitude was significantly correlated with the 5-HIAA concentration. There were no correlations between the P300 components and the HVA concentration. These findings suggest that the serotonergic system modulates the P300 component of ERPs in patients with DAT.     

Adaptation to the complexity of a task (a P300 study)

In numerous studies the P300 component of the event-related brain potential (ERP) has been shown to occur in connection with stimulus evaluation processes. 10 healthy right-handed volunteers (3 women, 7 men) aged from 25 to 30 years (mean age 27.8 years) participated in the experiments. One of 5 equiprobably occurring two-letter strings appeared on the screen always at the same central location. The strings informed the subjects about the difficulty of subsequently presented mental arithmetic tasks. After the letter strings vanished from the screen the subjects were to press the space-bar whereby a mental arithmetic task was presented corresponding in difficulty to the preceding message. The EEG was recorded by means of Ag/AgCl electrodes from frontal (F zeta), central (C zeta) and parietal (P zeta) midline electrodes referenced to linked earlobes. EEG and EOG were sampled 1200 ms, starting 200 ms prior to string onset. P300 peak latencies, peak amplitudes and areas in the time range 300 to 900 ms were measured in ERPs averaged selectively for the 5 strings. The main finding was that the P300 amplitude in ERPs to the 5 different strings varied in a U-shaped trend as a function of announced task difficulty. This result gives further evidence that the P300 amplitude reflects distance between incoming information and current adaptation level at the inferred internal dimension, i.e. task difficulty in this experiment.     

Lesions in thighs from hunted Brown Hares (<Emphasis Type="Italic">Lepus europaeus</Emphasis>) and microflora under vacuum-packaging storage

In two surveys, thighs of a total of 137 hunted hares were tested for the presence of intramuscular shots and femur fractures, which were detected in 42.7% and 29.2% of 274 thighs, respectively. Femur fractures were significantly associated with the presence of intramuscular shots. In the second survey (46 hares), 92 thighs were grouped into three categories, “A” (no fractures, no intramuscular shot), “B” (one intramuscular shot), and “C” (multiple shots and hematoma), with 49.0%, 33.6%, and 17.4%, respectively. Category “C” was found unfit for human consumption. During 7-day storage of vacuum-packed “A” and “B” thighs, total aerobic counts increased from initially 3.3 ± 0.3 (mean ± SD) and 4.1 ± 0.6 log cfu/g by ca. 2 log units when stored at 3–4°C, whereas the increase was clearly <1 log unit at 0°C. In comparison to temperature, differences between “A” and “B” category were less pronounced. Similar dynamics were observed for Enterobacteriaceae. In all categories, muscle pH values (mean = 5.83) were similar. It is concluded that storage at temperatures of ca. 4°C, although in compliance with EU legislation, does not afford keeping microbial contaminants in check, and thus will not preserve microbiological quality of vacuum-packed hare meat.     

Modifications of event-related evoked potentials in physiological and pathological aging of the brain

We compared the parameters of acoustic event-related evoked potentials (ERP; tone stimulation) in healthy young and healthy aged persons with those in patients suffering from Alzheimer’s disease (groups 1–3, respectively). It was found that the mean peak latencies (PL) of the components P1-N2 in group 1 were longer than those in group 2, and the absolute values of the amplitudes of these components were more negative. In Alzheimer patients (group 3), the PL of the components P1–P2 were much longer than those in group 2, and their peak-to-peak amplitudes dropped. The latencies of a simple sensorimotor reaction in groups 1–3 progressively increased (about three times). The ERP observed in two modes (“blackground” and “attention,” the latter with the performance of the sensorimotor reaction) were subjected to spectral analysis. Possible reasons for and mechanisms of those modifications of evoked potentials, which relate to physiological and pathological aging of the brain, are discussed.     

pH-Induced Molten Globule State of <Emphasis Type="Italic">Rhizopus niveus</Emphasis> Lipase is More Resistant Against Thermal and Chemical Denaturation Than Its Native State

Here, we have characterized four pH-dependent states: alkaline state, “B” (pH 9.0), native state, “N” (pH 7.4), acid-induced state, “A” (pH 2.2) and molten globule state, “MG” (pH 1.8) of Rhizopus niveus lipase (RNL) by CD, tryptophanyl fluorescence, ANS binding, DLS, and enzyme activity assay. This “MG” state lacks catalytic activity and tertiary structure but it has native-like significant secondary structure. The “R _h” of all the four states of RNL obtained from DLS study suggests that the molecular compactness of the protein increases as the pH of solution decreases. Kinetic analysis of RNL shows that it has maximum catalytic efficiency at state “B” which is 15-fold higher than state “N.” The CD and tryptophanyl fluorescence studies of RNL on GuHCl and temperature-induced unfolding reveal that the “MG” state is more stable than the other states. The DSC endotherms of RNL obtained at pH 9.0, 7.4, and 2.2 were with two transitions, while at pH 1.8 it showed only a single transition.     

Emotional cues during simultaneous face and voice processing: electrophysiological insights

Both facial expression and tone of voice represent key signals of emotional communication but their brain processing correlates remain unclear. Accordingly, we constructed a novel implicit emotion recognition task consisting of simultaneously presented human faces and voices with neutral, happy, and angry valence, within the context of recognizing monkey faces and voices task. To investigate the temporal unfolding of the processing of affective information from human face-voice pairings, we recorded event-related potentials (ERPs) to these audiovisual test stimuli in 18 normal healthy subjects; N100, P200, N250, P300 components were observed at electrodes in the frontal-central region, while P100, N170, P270 were observed at electrodes in the parietal-occipital region. Results indicated a significant audiovisual stimulus effect on the amplitudes and latencies of components in frontal-central (P200, P300, and N250) but not the parietal occipital region (P100, N170 and P270). Specifically, P200 and P300 amplitudes were more positive for emotional relative to neutral audiovisual stimuli, irrespective of valence, whereas N250 amplitude was more negative for neutral relative to emotional stimuli. No differentiation was observed between angry and happy conditions. The results suggest that the general effect of emotion on audiovisual processing can emerge as early as 200 msec (P200 peak latency) post stimulus onset, in spite of implicit affective processing task demands, and that such effect is mainly distributed in the frontal-central region.     

Seaweed meal as a protein source for the white shrimp Litopenaeus vannamei

The rhodophytes Hypnea cervicornis and Cryptonemia crenulata are abundant along the Brazilian coastline and are rich in nutrients. They may therefore be used as a source of protein in shrimp diets. The aim of the present study was to test this hypothesis. The experiment was conducted in a laboratory, where 10-day-old post-larvae aged underwent 7 days of acclimation in a 1,000 L tank. They were then kept in plastic aquariums, each containing 10 L, and 20 larvae were fed daily (10% of biomass) in four equal portions with one of four diets (five repetitions of each) for a period of 45 days. All diets contained 30% crude protein (isoprotein) and 300 kcal 100 g⁻¹ (isocaloric), with different percentages of seaweed powder: Diet “A” 39%; Diet “B” 26%, Diet “C” 13%, and Diet “D” without seaweed (control diet). Algae were collected, rinsed, dried and ground up for the feed formulations. Weight of the animals was measured at the beginning of the experiment and at 15-day intervals to assess their growth. The physico-chemical variables of the water were measured every 2 days. Final biomass, biomass gain and specific growth rate (SGR) exhibited no significant differences between treatments (P > 0.05). Survival rate was equal under the four experimental conditions, being consistent within four decimal places 95.2% to 97.00% (P > 0.05). Diets “A” and “B”, with a greater content of algae, exhibited better feed conversion (1.79:1 and 1.82:1) than Diets “C” and “D” (2.04:1 and 2.08:1) (P < 0.05). The physical-chemical variables of the water showed no significant variation and remained within the standards necessary for the wellbeing of the animals. If sufficient biomass of beached algae can be practically and economically collected, it may be used as a component in the making of shrimp feed.     

A global survey of haplotype frequencies and linkage disequilibrium at the DRD2 locus

A four-site haplotype system at the dopamine D2 receptor locus (DRD2) has been studied in a global sample of 28 distinct populations. The haplotype system spans about 25 kb, encompassing the coding region of the gene. The four individual markers include three TaqI restriction site polymorphisms (RSPs) – TaqI “A”, “B”, and “D” sites – and one dinucleotide short tandem repeat polymorphism (STRP). All four of the marker systems are polymorphic in all regions of the world and in most individual populations. The haplotype system shows the highest average heterozygosity in Africa, a slightly lower average heterozygosity in Europe, and the lowest average heterozygosities in East Asia and the Americas. Across all populations, 20 of the 48 possible haplotypes reached a frequency of at least 5% in at least one population sample. However, no single population had more than six haplotypes reaching that frequency. In general, African populations had more haplotypes present in each population and more haplotypes occurring at a frequency of at least 5% in that population. Permutation tests for significance of overall disequilibrium (all sites considered simultaneously) were highly significant (P<0.001) in all 28 populations. Except for three African samples, the pairwise disequilibrium between the outermost RSP markers, TaqI “B” and “A”, was highly significant with D’ values greater than 0.8; in two of those exceptions the RSP marker was not polymorphic. Except for those same two African populations, the 16-repeat allele at the STRP also showed highly significant disequilibrium with the TaqI “B” site in all populations, with D’ values usually greater than 0.7. Only four haplotypes account for more than 70% of all chromosomes in virtually all non-African populations, and two of those haplotypes account for more than 70% of all chromosomes in most East Asian and Amerindian populations. A new measure of the amount of overall disequilibrium shows least disequilibrium in African populations, somewhat more in European populations, and the greatest amount in East Asian and Amerindian populations. This pattern seems best explained by random genetic drift with low levels of recombination, a low mutation rate at the STRP, and essentially no recurrent mutation at the RSP sites, all in conjunction with an “Out of Africa” model for recent human evolution. Received: 14 January 1998 / Accepted 19 March 1998     

Dancers and fastball sports athletes have different spatial visual attention styles

Physical exercise and the training effects of repeated practice of skills over an extended period of time may have additive effects on brain networks and functions. Various motor skills and attentional styles can be developed by athletes engaged in different sports. In this study, the effects of fast ball sports and dance training on attention were investigated by event related potentials (ERP). ERP were recorded in auditory and visual tasks in professional dancer, professional fast ball sports athlete (FBSA) and healthy control volunteer groups consisting of twelve subjects each. In the auditory task both dancer and FBSA groups have faster N200 (N2) and P300 (P3) latencies than the controls. In the visual task FBSA have faster latencies of P3 than the dancers and controls. They also have higher P100 (P1) amplitudes to non-target stimuli than the dancers and controls. On the other hand, dancers have faster latencies of P1 and higher N100 (N1) amplitude to non-target stimuli and they also have higher P3 amplitudes than the FBSA and controls. Overall exercise has positive effects on cognitive processing speed as reflected on the faster auditory N2 and P3 latencies. However, FBSA and dancers differed on attentional styles in the visual task. Dancers displayed predominantly endogenous/top down features reflected by increased N1 and P3 amplitudes, decreased P1 amplitude and shorter P1 latency. On the other hand, FBSA showed predominantly exogenous/bottom up processes revealed by increased P1 amplitude. The controls were in between the two groups.     

Auditory selective attention in middle-aged and elderly subjects: an event-related brain potential study

Reaction times (RTs) and event-related brain potentials (ERPs) were recorded in middle-aged (MA) and elderly (ELD) subjects performing an auditory selective attention task. Subjets attended to tone bursts of a specified pitch and ear of delivery and responded to occasional longer duration target tones (75 vs. 25 msec). Infrequent novel stimuli (computer synthesized sounds and digitized environmental noises) were also included in the stimulus sequence.No significant age-related differences were found in the speed or accuracy of target detection. However, in both groups, RTs were delayed (by more than 300 msec) to targets that followed novel sounds. The prolongation was greater following novel sounds in the attended ear, particularly in the ELD group.The effects of selective attention on ERPs to standard tones were isolated as negative difference waves (Nds) by subtracting ERPs to non-attended stimuli from ERPs to the same signals when attended. Nds had similar amplitudes, latencies of onset (60 msec), and distributions in ELD and MA groups. In both groups, Nd waves were more prominent following right ear stimulation, reflecting possible hemispheric asymmetries of generators in posterior temporal regions.The mismatch negativity (MMN) was isolated by subtracting ERPs to standard tones from ERPs to deviant stimuli. MMN amplitudes were reduced in the ELD group. There was also a significant change in MMN distribution with age: the MMN was larger over the right hemisphere for MA subjects but larger over the left for ELD subjects. Elderly subjects showed a trend toward smaller P3 amplitudes and delayed P3 latencies, but group differences did not reach statistical significance. ERPs to novel sounds were characterized by centrally distributed N2 and P3a components. Although the novel P3a was enhanced with attention, no novel Nd waves could be isolated. This suggests that novel sounds fell outside the focus of attention.     

<Emphasis Type="Italic">“Pseudoalteromonas januaria”</Emphasis> SUT 11 as the Source of Rare Lipodepsipeptides

The marine bacterium “Pseudoalteromonas januaria” SUT 11 isolated from a seawater sample produced the rare cell-bound cyclic lipodepsipeptides A/A′, B/B′, and C/C′. The matrix-assisted laser desorption/ionization mass spectra indicated that one bromine atom presented in the peptides B/B′ and C/C′, whereas the component A/A′ contained no bromine atom. The acyldepsipeptides A/A′–C/C′ have an identical amino acid sequence, Thr-Val-Asn-Asn-Leu/allo-Ile, but differed in C-terminal amino acid and acyl moieties. Peptides A–C have Leu as a C-terminal amino acid, whereas peptides A′-C′ have allo-Ile. Acyl moieties in peptides A/A′, B/B′, and C/C′ have been found to consist of 11-(4′-hydroxyphenyl)-undeca-2,4,6,8,10-pentaenic acid, 9-(3′-bromo-4′-hydroxyphenyl)-nona-2,4,6,8-tetraenic acid, and 11-(3′-bromo-4′-hydroxyphenyl)-undeca-2,4,6,8,10-pentaenic acid, respectively. The structure of a main pair of peptides B/B′ with molecular masses 843/845 Da has been determined by means of ultraviolet, infrared, and two-dimensional nuclear magnetic resonance spectroscopy. We have demonstrated that tandem nano-electrospray ionization mass spectrometry is a very efficient way for the fast and sensitive investigation of lipopeptides A/A′ and C/C′ with molecular masses 791 and 869/871 Da, respectively, which have been isolated in small amounts.