Unstressed Counterparts Research Articles

Harnessing adrenergic blockade in stress-promoted TNBC in vitro and solid tumor in vivo: disrupting HIF-1α and GSK-3β/β-catenin driven resistance to doxorubicin.

Sympathetic activation triggered by chronic stress afflicting cancer survivors is an emerging modulator of tumorigenesis. Adrenergic blockade was previously associated with improving response to doxorubicin (DOX) in triple-negative breast cancer (TNBC), yet the precise underlying mechanisms remain obscure. The resilience of cancer stem cells (CSCs) during chemotherapy fosters resistance and relapse. Hypoxia-inducible factor-1α (HIF-1α) and β-catenin are intertwined transcriptional factors that enrich CSCs and evidence suggests that their expression could be modulated by systemic adrenergic signals. Herein, we aimed to explore the impact of adrenoreceptor blockade using carvedilol (CAR) on DOX and its potential to modulate CSCs overcoming chemoresistance. To achieve this aim, in vitro studies were conducted using adrenaline-preincubated MDA-MB-231 cells and in vivo studies using a chronic restraint stress-promoted solid tumor mouse model. Results revealed that adrenaline increased TNBC proliferation and induced a phenotypic switch reminiscent of CSCs, as evidenced by enhanced mammosphere formation. These results paralleled an increase in aldehyde dehydrogenase-1 (ALDH-1) and Nanog expression levels as well as HIF-1α and β-catenin upsurge. In vivo, larger tumor volumes were observed in mice under chronic stress compared to their unstressed counterparts. Adrenergic blockade using CAR, however, enhanced the impact DOX had on halting TNBC cell proliferation and tumor growth via enhanced apoptosis. CAR also curbed HIF-1α and β-catenin tumor levels subsequently suppressing ALDH-1 and SOX2. Our study unveils a central role for HIF-1α linking stress-induced sympathetic activation fueling CSC enrichment via the β-catenin pathway. It also highlights novel insights into CAR's capacity in reversing DOX chemoresistance in TNBC.

Moderate heat stress-induced sterility is due to motility defects and reduced mating drive in C. elegans Males.

Moderate heat stress negatively impacts fertility in sexually reproducing organisms at sublethal temperatures. These moderate heat stress effects are typically more pronounced in males. In some species, sperm production, quality, and motility are the primary cause of male infertility during moderate heat stress. However, this is not the case in the model nematode Caenorhabditis elegans, where changes in mating behavior are the primary cause of fertility loss. We report that heat-stressed C. elegans males are more motivated to locate and remain on food and less motivated to leave food to find and mate with hermaphrodites than their unstressed counterparts. Heat-stressed males also demonstrate a reduction in motility that likely limits their ability to mate. Collectively these changes result in a dramatic reduction in reproductive success. The reduction in mate searching behavior may be partially due to increased expression of the chemoreceptor odr-10 in the AWA sensory neurons, which is a marker for starvation in males. These results demonstrate that moderate heat stress may have profound and previously underappreciated effects on reproductive behaviors. As climate change continues to raise global temperatures, it will be imperative to understand how moderate heat stress affects behavioral and motility elements critical to reproduction.

Acoustic analysis of lexical stress in Greek preschool children

Lexical stress carries significant functional load in Greek; there are several pairs and even triplets of words that are differentiated only by stress position. Greek stressed vowels are longer and have a greater amplitude compared to their unstressed counterparts. Lexical stress is also indirectly signalled by pitch movement (Arvaniti, 2007). The trajectory of lexical stress development has received little attention, both in Greek and in the international literature, especially regarding the acoustic analysis of prominence. Therefore, the aim of this study was to investigate the acoustic realisation of stress during Greek acquisition. To that end, 24 typically developing children aged 4;7 to 6;4 (years;months), and 24 adults aged 20 to 25, carried out a word repetition task involving 20 minimal stress pairs (15 real words and five non-words). Duration, intensity and F0 variation, indices of the relative prominence of stressed to unstressed vowels, were calculated. Overall, although the use of the intensity cue for lexical stress did not differ significantly between the two groups, children tended to use the vowel duration cue to a lesser extent than adults to signal lexical stress position. On the other hand, F0 variation indices were significantly higher in the children’s data. Additionally, the acoustic analysis indicated that children utilized the pattern of devoicing unstressed vowels, a specific type of vowel reduction optionally applied in Greek, much more extensively than adults. Finally, although for the most part the word productions carried unequivocal and correct lexical stress, in a few cases children, contrary to adults, had difficulties signalling lexical stress position in a perceptually transparent manner. This study is one of the few attempts to describe the acoustic characteristics of lexical stress in Greek typical development.

Chloroplast proteomics reveals transgenerational cross-stress priming in Pinus radiata

Plants do have stress memory and chloroplast signaling has been revealed as crucial element to acquire and extend this memory into future generations, allowing plant adaptation to changing environments and providing novel tools in the field of crop improvement. Despite the process is known, how a plant is capable to transfer some aspects of its “life-long learning” to progeny, as well as the role of chloroplast proteome mediating transgenerational cross-stress priming effects, remain unknown. To fill this gap, this study examines the impact of the physiological status of Pinus radiata parentals over the capacity of their progeny to acclimate to their first stress period in a common garden experiment. Seedlings were originated in subpopulations with the same genetic background, but grown in two locations with contrasting environments (stressed vs non-stressed plants). Physiological measurements (fluorescence-based and biochemistry) and chloroplast proteomics were employed to study plant stress responses. Results demonstrated a differential seed priming. Those seedlings originated from stressed plants responded quicker and more efficiently than those originated from unstressed counterparts. Unprimed responses showed proteome remodeling driven by lipid peroxidation and photoinhibition, whereas primed subpopulation quickly faced stress rearranging secondary metabolism, replacing damaged lipids, reducing photooxidative damage, and promoting photorespiration and redox homeostasis in order to reduce lipoperoxidation and maintain photosynthesis. These results not only delve into cross-stress memory in long-lived species, but also suggest a new biotechnological potential for current seed orchards if adequate management is performed. • Parental growing conditions have transgenerational cross-stress priming effects. • Subpopulation originated from stressed plants responded quicker and more efficiently. • Primed responses were driven by photorespiration, redox, and secondary metabolism. • Knowledge acquired suggests a new biotechnological potential for seed orchards.

The supralaryngeal articulation of stress and accent in Greek

It is well reported that articulatory movements comprising prominence units are longer, larger, and faster than their non-prominent counterparts. However, it is unclear whether these effects arise at the level of lexical stress, accent, or both, reflecting a hierarchy of prominence, i.e., being stronger when induced by accent as opposed to stress. It is also uncertain whether prominence-induced kinematic effects are invariant across positions of stress within the word, types of focus that accent denotes, and positions of words in the phrase. Here, we use an electromagnetic articulography (EMA) study to assess the supralaryngeal kinematic correlates of prominence in Greek across three stress positions (antepenultimate, penultimate, ultimate; i.e., all possible stress positions in Greek), two accentual conditions (accented and de-accented), and two phrasal positions (phrase-medial and phrase-final). Focus type is also considered, with the accentual conditions coming from two types of focus (broad and narrow), while the de-accented conditions are by default unfocused. Our results indicate that stressed syllables involve longer, larger, and faster gestures than their unstressed counterparts, regardless of the position of stress within the word. Notably, variation in velocity is accounted for by variation in displacement. Presence of accent does not further expand the stressed gestures, although it is related to minimal kinematic changes across the whole word, the exact profile of which depends on stress position. With the exception of final vowel duration, focus type is not systematically encoded in these kinematic effects. Finally, interactions are detected between the kinematic profile of prominence and that of boundaries. Implications of our findings for the hierarchy of prominence and its cross-linguistic differences are discussed, and a gestural account of prominence and boundaries is put forward.

Chronic stress differentially altersmRNAexpression of opioid peptides and receptors in the dorsal hippocampus of female and male rats

Chronic immobilization stress (CIS) results in sex-dependent changes in opioid peptide levels and receptor subcellular distributions within the rat dorsal hippocampus, which are paralleled with an inability for males to acquire conditioned place preference (CPP) to oxycodone. Here, RNAScope in situ hybridization was used to determine the expression of hippocampal opioid peptides and receptors in unstressed (US) and CIS estrus female and male adult (∼2.5 months old ) Sprague Dawley rats. In all groups, dentate granule cells expressed PENK and PDYN; additionally, numerous interneurons expressed PENK. OPRD1 and OPRM1 were primarily expressed in interneurons, and to a lesser extent, in pyramidal and granule cells. OPRK1-was expressed in sparsely distributed interneurons. There were few baseline sex differences: US females compared to US males had more PENK-expressing and fewer OPRD1-expressing granule cells and more OPRM1-expressing CA3b interneurons. Several expression differences emerged after CIS. Both CIS females and males compared to their US counterparts had elevated: (1) PENK-expressing dentate granule cells and interneurons in CA1 and CA2/3a; (2) OPRD1 probe number and cell expression in CA1, CA2/3a and CA3b and the dentate gyrus; and (3) OPRK1-expressing interneurons in the dentate hilus. Also, CIS males compared to US males had elevated: (1) PDYN expression in granule cells; (2) OPRD1 probe and interneuron expression in CA2/3a; (3) OPRM1 in granule cells; and (4) OPRK1 interneuron expression in CA2/3a. The sex-specific changes in hippocampal opioid gene expression may impact network properties and synaptic plasticity processes that may contribute to the attenuation of oxycodone CPP in CIS males.

Características acústicas de las vocales tónicas y átonas del español rioplatense. Efectos del estilo de habla y del contexto consonántico

Produced vowels in a style focused on speech (isolated words reading) exhibit more peripheral formants and more spectral change than conversational vowels (text reading). This study explored the interaction between lexical stress and speech style by comparing the production of stressed and unstressed /a e o/ River Plate Spanish vowels produced by word reading versus the text reading in three different consonantal contexts. Formant frequency in the stable point of the vowel (50%) and spectral change were examined. Results revealed that speech style mainly affected the F2 of stressed and unstressed vowels /e/ and /o/. In the word reading, /e/ was more anterior and /o/ more posterior. Nevertheless, this modification in the F2 due to speech style was not observed in all the consonantal contexts. Regarding F1, only stressed /a/ increased its F1 in word reading in relation to conversational speech, independent of the phonetic context. Concerning the effect of the lexical stress, stressed /a/ and /o/ were produced with a higher F1 than the unstressed counterparts, while stressed /e/ showed a higher F2 than unstressed /e/. As for the spectral change, vowels /a/ and /o/ evinced a higher spectral variation in the word reading than in text reading, unlike /e/ that showed an opposite pattern. Only the unstressed /a/ in bilabial context had a greater spectral change than the stressed /a/.

Stress-Induced Acoustic Variation in L2 and L1 Spanish Vowels

Aim: We assessed the effect of lexical stress on the duration and quality of Spanish word-final vowels /a, e, o/ produced by American English late intermediate learners of L2 Spanish, as compared to those of native L1 Argentine Spanish speakers. Methods: Participants read 54 real words ending in /a, e, o/, with either final or penultimate lexical stress, embedded in a text and a word list. We measured vowel duration and both F1 and F2 frequencies at 3 temporal points. Results: stressed vowels were longer than unstressed vowels, in Spanish L1 and L2. L1 and L2 Spanish stressed /a/ and /e/ had higher F1 values than their unstressed counterparts. Only the L2 speakers showed evidence of rising offglides for /e/ and /o/. The L2 and L1 Spanish vowel space was compressed in the absence of stress. Conclusion: Lexical stress affected the vowel quality of L1 and L2 Spanish vowels. We provide an up-to-date account of the formant trajectories of Argentine River Plate Spanish word-final /a, e, o/ and offer experimental support to the claim that stress affects the quality of Spanish vowels in word-final contexts.

Early hippocampal volume loss as a marker of eventual memory deficits caused by repeated stress.

Exposure to severe and prolonged stress has detrimental effects on the hippocampus. However, relatively little is known about the gradual changes in hippocampal structure, and its behavioral consequences, over the course of repeated stress. Behavioral analyses during 10 days of chronic stress pointed to a delayed decline in spatial memory, the full impact of which is evident only after the end of stress. In contrast, concurrent volumetric measurements in the same animals revealed significant reduction in hippocampal volumes in stressed animals relative to their unstressed counterparts, as early as the third day of stress. Notably, animals that were behaviorally the worst affected at the end of chronic stress suffered the most pronounced early loss in hippocampal volume. Together, these findings support the view that not only is smaller hippocampal volume linked to stress-induced memory deficits, but it may also act as an early risk factor for the eventual development of cognitive impairments seen in stress-related psychiatric disorders.

Honey bee workers that are pollen stressed as larvae become poor foragers and waggle dancers as adults.

The negative effects on adult behavior of juvenile undernourishment are well documented in vertebrates, but relatively poorly understood in invertebrates. We examined the effects of larval nutritional stress on the foraging and recruitment behavior of an economically important model invertebrate, the honey bee (Apis mellifera). Pollen, which supplies essential nutrients to developing workers, can become limited in colonies because of seasonal dearths, loss of foraging habitat, or intensive management. However, the functional consequences of being reared by pollen-stressed nestmates remain unclear, despite growing concern that poor nutrition interacts with other stressors to exacerbate colony decline. We manipulated nurse bees’ access to pollen and then assessed differences in weight, longevity, foraging activity, and waggle-dance behavior of the workers that they reared (who were co-fostered as adults). Pollen stress during larval development had far-reaching physical and behavioral effects on adult workers. Workers reared in pollen-stressed colonies were lighter and shorter lived than nestmates reared with adequate access to pollen. Proportionally fewer stressed workers were observed foraging and those who did forage started foraging sooner, foraged for fewer days, and were more likely to die after only a single day of foraging. Pollen-stressed workers were also less likely to waggle dance than their unstressed counterparts and, if they danced, the information they conveyed about the location of food was less precise. These performance deficits may escalate if long-term pollen limitation prevents stressed foragers from providing sufficiently for developing workers. Furthermore, the effects of brief pollen shortages reported here mirror the effects of other environmental stressors that limit worker access to nutrients, suggesting the likelihood of their synergistic interaction. Honey bees often experience the level of stress that we created, thus our findings underscore the importance of adequate nutrition for supporting worker performance and their potential contribution to colony productivity and quality pollination services.

Stress and dietary behaviour among first-year university students in Australia: Sex differences

ObjectiveThe aim of this study was to examine the relationship between stress and food selection patterns by sex among first-year undergraduate students studying in an Australian university. MethodsParticipating in this cross-sectional study were 728 (331 men and 397 female students) first-year students, ages >18 y, attending the Gold Coast Campus of Griffith University. Data were collected using a self-administered questionnaire consisting of three sections: sociodemographic information, stress measures, and a 7-d food frequency questionnaire. ResultsMore than half (52.9%) of the participants were found to suffer from some level of stress, with relatively more female students (57.4%) suffering than men (47.4%). Men who experienced mild to moderate levels of stress were two to three times more likely to eat cereal foods (P < 0.01), fish/seafood (P < 0.001), and protein powder (P < 0.05). They also tended to eat more meat alternatives (P < 0.05), highly processed foods (P < 0.05), and to drink more alcohol (P < 0.05) than unstressed male students. However, they were less likely to consume vegetables and fruit (P < 0.05) compared with their unstressed counterparts. The trend analysis results indicated significant dose–response patterns in the relationship between stress level and consumption of cereal food, meat alternatives, vegetables and fruit (negative trend), highly processed food, protein powder, beverages and alcoholic beverages (all P < 0.05). Female students who experienced mild to moderate stress were 2.22 times more likely to eat processed food (P < 0.01) than unstressed female students. Female students who experienced severe stress were less likely to consume meat alternatives (P < 0.05) than their unstressed counterparts. Significant dose–response trends were found in the relationship between stress levels and the consumption of meat alternatives, vegetables and fruit (both negative trends), and processed food (all P < 0.01). ConclusionThese results demonstrate a clear difference in food selection patterns between stressed male and female students, with stress being a more significant predictor of unhealthy food selection among male students. Further research is needed using a qualitative approach to understand how stress and eating behavior are related in university students.

Vowel pronunciation in open syllables in spontaneously spoken Standard Dutch: Exploring a phonological constraint in a listening task

According to the Bimoraic Constraint (Kager 1989) and the Minimal Rhyme Constraint (Booij 1995), Dutch syllables by default end in either a tense vowel or a lax vowel followed by a consonant. Syllables ending in a lax vowel do not meet the phonological requirements of a felicitous syllable. The present paper reports on a listening task in which this phonological constraint is explored. Three linguists were asked to categorize 3984 vowels in open syllables in bisyllabic Dutch words with two full vowels (e.g., gl o baal [glo'bal] ‘global’, dict ee [dɪk'te] ‘dictation’). The source words originated from spontaneously spoken Standard Dutch by 80 Flemish and 80 Dutch teachers of Dutch. The main variables of this study were stress (stressed vs. unstressed syllables), relative position in the word (first vs. second syllable), vowel (/a/-/e/-/i/-/o/) and country (Flanders vs. the Netherlands). The present study did not find conclusive empirical evidence for the phonological constraint at issue. In other words, it was not unusual for Dutch syllables to end in a lax vowel. As expected, vowels in stressed syllables are labeled as tense more often than their unstressed counterparts. More lax realizations were found in the first syllable than in the second, and Flemish vowels were more often categorized as lax than Dutch vowels. The vowel with the lowest tense-score was /a/.

Old Irish Tonic Pronouns as Extraclausal Constituents

Old Irish Tonic Pronouns as Extraclausal Constituents

Coarsening of elastically stressed, strongly anisotropic driven thin films

A diffuse interface model is developed to investigate the growth and coarsening in driven thin films under the influence of strong surface energy anisotropy, misfit strain, mass deposition, and diffusion. Two high-order regularizations are used to remove the ill-posedness introduced by the strong anisotropy: a Willmore (or bending energy) regularization and a simplified linear regularization. For similar effective growth rates and regularization strengths, the two regularizations undergo similar dynamics and coarsening, as peaks (antikinks) and valleys (kinks) of the corrugated surface are removed as the film grows. Competition among the influence of elastic strains, surface energy anisotropy and the rate of deposition lead to a change in the coarsening events compared to that observed in unstressed thin films. As the rate of deposition is increased, the primary coarsening events change from a combination of both antikink-ternary and binary events at low deposition rates, to binary events at moderate rates, and finally to kink-ternary events at high rates. The kink-ternary events are the only coarsening events observed in growing unstressed films at all deposition rates. Accordingly, the coarsening dynamics of two-dimensional (2D) stressed films is much faster than for unstressed films at low deposition rates. In addition, deep grooves may form in the film due to the Asaro-Tiller-Grinfeld instability and may lead to the breakup of the film into islands. At higher deposition rates, the evolution of stressed films is found to become limited by the surface energy anisotropy and the regularizations, which inhibits groove formation. The corresponding coarsening events and rates then tend toward those observed in unstressed films. Preliminary results of 3D thin films indicate that coarsening processes in elastically stressed films are also much faster than their unstressed counterparts at low deposition rates. In three dimensions, however, the coarsening events are also found to involve saddles.

Dutch word stress as pronounced by Indonesian students

This study focuses on the way in which the Dutch monophthongal vowels are pronounced by Indonesian students. To investigate whether Indonesian students realize the Dutch vowels correctly, especially when they are stressed, I analysed duration and quality of stressed and unstressed Dutch vowels. Measurements were done on the duration and the formant frequencies of the vowels spoken by Indonesian students and by native speakers of Dutch as well. Statistical analysis showed that in general the differences in duration between vowels spoken by the Indonesian students and by the native speakers were not significant. However, the effect of stress on the lengthening of the vowels was stronger for the Indonesian students than for the native speakers. In addition, statistical analysis of the formant frequencies confirmed that the non-native speakers realized the Dutch vowels slightly differently from the Dutch native speakers. The Indonesian students pronounced the stressed vowels more clearly than their unstressed counterparts; yet their vowel diagram is smaller than the vowel diagram of the native speakers.

Increased CRF2 expression in the dorsal raphe is associated with passive behavioral responses to stress

The dorsal raphe (DR)‐serotonin (5‐HT) system is implicated in stress‐related psychiatric disorders, like depression. Corticotropin‐releasing factor (CRF) modulates activity of this system during stress via activation of two receptors: CRF1 and CRF2. CRF1 mediated inhibition of the DR‐5‐HT system facilitates active behavioral responses to stress. In contrast, CRF2 can excite the DR‐5‐HT system, an effect that may mediate passive responses to stress. Here we used genetic, behavioral, and pharmacological models to determine whether changes in CRF2 expression in the DR are associated with passive behavior. Western Blots were first used to demonstrate that rats of the behaviorally passive Wistar Kyoto strain express more CRF2 protein in the DR than Sprague‐Dawley (SD) rats. In the second experiment, SD rats exposed to chronic social defeat, which results in passive behavior on the forced swim test (FST), expressed more CRF2 in the DR than their unstressed counterparts. Finally, chronic antidepressant treatment that decreases passive responses on the FST resulted in fewer CRF2 in the DR. None of these models altered DR expression of CRF1. These studies suggest that greater CRF2 expression in the DR correlates with a passive behavioral strategy. Because passive responses to stress are associated with increased vulnerability to depression in humans, CRF2 may be a novel target for treating stress‐related disorders.

Temporal properties of spontaneous speech—a syllable-centric perspective

Temporal properties of the speech signal are of potentially great importance for understanding spoken language and may provide significant insight into the manner in which listeners process spoken language with so little apparent effort. It is the thesis of this study that durational properties of phonetic segments differentially reflect the amount of information contained within a syllable, and that syllable prominence is an indirect measure of linguistic entropy. The ability to understand spoken language appears to depend on a broad distribution of syllable duration, ranging between 50 and 400 ms (for American English), which is reflected in the modulation spectrum of the acoustic signal. The upper branch of the modulation spectrum (6–20 Hz) reflects unstressed syllables, while the lower branch (<5 Hz) represents mostly heavily stressed syllables. Low-pass filtering the modulation spectrum reduces the intelligibility of spoken sentences in a manner consistent with the differential contribution of stressed and unstressed syllables to understanding spoken language. The origins of this phenomenon are investigated in terms of the durational properties of phonetic segments contained in a corpus of spontaneous American English telephone dialogues (SWITCHBOARD). Forty-five minutes of this material was manually annotated with respect to stress accent, and the relation between accent level and segmental duration examined. Statistical analysis indicates that much of the temporal variation observed at the syllabic and phonetic-segment levels can be accounted for in terms of two basic parameters: (1) stress-accent pattern and (2) position of the segment within the syllable. Segments are generally longest in heavily stressed syllables and shortest in syllables without stress. However, the magnitude of accent's impact on duration varies as a function of syllable position. Duration of the nucleus is heavily affected by stress-accent level—heavily stressed nuclei are, on average, twice as long as their unstressed counterparts, while the duration of the onset is also significantly sensitive to stress, but to a lesser degree. In contrast, stress has relatively little impact on coda duration. This pattern of durational variation suggests that the vocalic nucleus absorbs much of the impact of stress accent and potentially sets the register for interpreting the phonetic segments contained within the syllable. Moreover, the data imply that linguistic entropy is not uniformly distributed across the syllable—the onset and nucleus convey more information than the coda.

Modeling lexical stress in continuous speech recognition for Dutch

The acoustic realization of vowels with lexical stress generally differs substantially from their unstressed counterparts, which are more reduced in spectral quality, shorter in duration, weaker in intensity and tend to have a flatter spectral tilt. Therefore, in a continuous speech recognizer (CSR) it would appear profitable to train separate models for the stressed and unstressed variants of each vowel. In the experiments reported on here, we applied stress modeling in both training and testing of the recognizer. Recognition experiments on an independent test set showed that recognition rates did not improve by this use of stress in our CSR. However, if we swapped the stress markers in the recognition lexicon the recognition rates did significantly deteriorate. This demonstrated that the acoustic models for the stressed and unstressed variants of the vowels were different. A pitfall in this experiment was that lexical stress information and phonemic context were possibly confounded. In a follow-up experiment we controlled for context by using generalized context-dependent models. In this experiment the recognition results were not improved either, although the vowel models were better tailored to capture lexical stress-related information. We conclude that the mapping of lexical stress to the acoustic surface of fluent speech is not sufficiently straightforward to be of direct benefit for CSR, due to interaction of lexical stress with rhythm and sentence accent in real speech.

Effect of heat stress on promoter binding by transcription factors in the cytosol of the archaeon Methanosarcina mazeii

Regulation of archaeal stress genes is not yet fully understood. This work is part of a research effort aimed at elucidating the molecular mechanisms of transcription initiation and regulation of the stress genes in the hsp70(dnaK) locus of the mesophilic, methanogenic archaeon Methanosarcina mazeii. The locus has the stress genes 5′-grpE-hsp70(dnaK)-hsp40(dnaJ)-3′ encoding the chaperone machine components GrpE, Hsp70(DnaK), and Hsp40(DnaJ), respectively, flanked by non-heat shock inducible genes, orf16 and orf11-trkA. Thus, the M. mazeii hsp70(dnaK) locus offers the opportunity for studying heat shock and non-heat shock inducible genes side by side. The objectives of the work reported here were to develop procedures for studying basal transcription factors in the cytosol of M. mazeii and their interaction with these genes' promoters in stressed cells for comparison with unstressed counterparts. The preparation of non-radioactive DNA probes for electrophoretic mobility shift assay (EMSA), and the combination of EMSA with Western blotting for DNA-binding protein identification were standardized for this investigation. DNA probes bearing the genes' promoter regions were used for detecting and identifying DNA-binding proteins in the cytosol of unstressed and heat-shocked cells. Cytosolic TATA-binding protein (TBP) was found to bind the stress-gene promoters in both unstressed and heat-shocked cells but more strongly in the latter. Likewise, in stressed cells TBP-transcription factor B (TFB)(TFIIB) association was increased by comparison with unstressed controls. The level of cytosolic TBP assessed by its DNA-binding activity using EMSA remained unchanged during the various phases of culture growth in the absence of heat stress. The results indicate that heat stress of cells in culture modulates the level and/or the stress-gene promoter-binding activity of the M. mazeii TBP, and enhances TBP-TFB association in the cytosol and DNA binding.

Magnetic force microscopy study of dense stripe domains in Fe-B/Co-Si-B multilayers and the evolution under an external applied field

The effect of the permanent compression acting on multilayered Fe-B/Co-Si-B thin films has been studied by using magnetic force microscopy (MFM). Since both materials exhibit positive and negative saturation magnetostriction, respectively, the magnetic-moment distribution and thus the domain structure of these multilayers are strongly dependent on the thickness of each layer. Different MFM contrast levels and domain sizes have been measured in stressed and unstressed multilayers with various Fe-B and Co-Si-B layer thickness. Both kinds of samples, stressed and unstressed thin films, present a weak perpendicular anisotropy. For identical composition of the multilayers, an increase of the magnetization component perpendicular to the sample plane has been observed in stressed samples compared to their unstressed counterparts. In addition, the effect of the stress on the magnetization process has been studied by analyzing the evolution of the domain structure with an externally applied magnetic field in MFM imaging.