Adaptation to Teaching Loads in New Educational Institutions

The authors analyzed physical development and training, nonspecific immunity, free-radical oxidation, hemodynamic indices, and autonomic regulation in pupils from the first to ninth grade levels of a new educational institution (gymnasium). All of these indices were influenced by the motor activity level. The children with hypokinesia had disadaptive changes in hemodynamics, weakened immunity, and lower antioxidant protection. The authors suggest principles for the pathogenetic correction of these disorders.     

Adaptation of Cochlear Amplification to Low Endocochlear Potential

Endocochlear potential (EP) is essential for cochlear amplification by providing the voltage source needed to drive outer hair cell (OHC) transducer current, which leads to OHC electromechanical force. An early study using furosemide to reversibly reduce EP showed that distortion product otoacoustic emissions (DPOAEs) recovered before EP. This indicated that cochlear amplification may be able to adjust to a new, lower EP. To investigate the mechanism of this adjustment, the extracellular OHC voltage, which we term local cochlear microphonic (LCM), was measured simultaneously with DPOAE and EP while using intraperitoneal (IP) and intravenous injection of furosemide to reversibly reduce EP. With IP injection, the DPOAEs recovered fully, whereas the EP was reduced, but LCM showed a similar time course as EP. The DPOAEs failed to accurately report the variation of cochlear amplification. With intravenous injection, for which both reduction and recovery of EP are known to occur relatively quickly compared to IP, the cochlear amplification observed in LCM could attain nearly full or even full recovery with reduced EP. This showed the cochlea has an ability to adjust to diminished operating condition. Furthermore, the cochlear amplifier and EP recovered with different time courses: cochlear amplification just started to recover after the EP was nearly fully recovered and stabilized. Using a Boltzmann model and the second harmonic of the LCM to estimate the mechanoelectric transducer channel operating point, we found that the recovery of cochlear amplification occurred with recentering of the operating point.     

Psychophysiological Study of Intellectual Activity under Bilingual Conditions

The intellectual activity was studied in schoolchildren and adults with tests for association of words, associated learning of paired words, short-term memory, and concentration of attention upon the presentation of discrete and grouped bilingual verbal stimuli. Qualitative and quantitative differences in processes assessed with the tests were found. It was supposed that switching from one language to another, i.e., from one level of verbal thinking to another, is accompanied by the involving of new elements of the structural-functional system of speech.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 3, 2005, pp. 55–58.Original Russian Text Copyright © 2005 by A. Hayrapetian, V. Maloian, N. Maloian, Tatevosian, N. Hayrapetian.     

Effect on Membrane Potential and Electrical Activity of Adding Sodium to Sodium-Depleted Cardiac Purkinje Fibers

Canine cardiac Purkinje fibers exposed to Na-free solutions containing 128 mM TEA and 16 mM Ca show resting potentials in the range -50 to -90 mV; if the concentration of Na in the perfusate is raised from 0 to 4 to 24 mM, hyperpolarization follows. If the initial resting potential is low, the hyperpolarization tends to be greater; the average increase in the presence of 8 mM Na is 14 mV. Such hyperpolarization is not induced by adding Na to K-free solutions, is not seen in cooled fibers, or in fibers exposed to 10^-3 M ouabain, nor is it induced by adding Li and thus may result from electrogenic sodium extrusion. Fibers exposed to Na-free solutions are often spontaneously active; if they are quiescent they often show repetitive activity during depolarizing pulses. Such spontaneous or repetitive activity is suppressed by the addition of Na. This suppression may or may not be related to the hyperpolarization.     

Estimating the Potential for Adaptation of Corals to Climate Warming

The persistence of tropical coral reefs is threatened by rapidly increasing climate warming, causing a functional breakdown of the obligate symbiosis between corals and their algal photosymbionts (Symbiodinium) through a process known as coral bleaching. Yet the potential of the coral-algal symbiosis to genetically adapt in an evolutionary sense to warming oceans is unknown. Using a quantitative genetics approach, we estimated the proportion of the variance in thermal tolerance traits that has a genetic basis (i.e. heritability) as a proxy for their adaptive potential in the widespread Indo-Pacific reef-building coral Acropora millepora. We chose two physiologically different populations that associate respectively with one thermo-tolerant (Symbiodinium clade D) and one less tolerant symbiont type (Symbiodinium C2). In both symbiont types, pulse amplitude modulated (PAM) fluorometry and high performance liquid chromatography (HPLC) analysis revealed significant heritabilities for traits related to both photosynthesis and photoprotective pigment profile. However, quantitative real-time polymerase chain reaction (qRT-PCR) assays showed a lack of heritability in both coral host populations for their own expression of fundamental stress genes. Coral colony growth, contributed to by both symbiotic partners, displayed heritability. High heritabilities for functional key traits of algal symbionts, along with their short clonal generation time and high population sizes allow for their rapid thermal adaptation. However, the low overall heritability of coral host traits, along with the corals'' long generation time, raise concern about the timely adaptation of the coral-algal symbiosis in the face of continued rapid climate warming.     

Biochemical Adaptation of Barley Root Cells to Toxic Substances. II. Effect of Heavy Metals on Phosphohydrolase Activity

We studied the effect of heavy metals such as Cu, Zn, Cd, and Pb on the activity of membrane-bound and soluble phosphohydrolases of barley root cell apoplast. The effect of heavy metals on the activity of acid phosphatase and acid nucleotidases proved to depend on the presence of calcium and magnesium ions in the incubation buffer, the condition and form of the enzymes, as well as the dose and moment of the addition of heavy metals. We propose changing the activity of acid phosphohydrolases in barley root cell apoplast as a possible mechanism of barley adaptation to the toxic effect of heavy metals.     

Psychophysiological Responses to Salsa Dance

Speculation exists whether dance provides physiological stimuli adequate to promote health and fitness benefits. Unfortunately, research to date has not addressed the affective and exertional responses to dance. These responses are of interest as positive affective and exertional responses experienced during physical activity may play an important role in predicting adherence. The present study aims to examine the psychophysiological responses of different Salsa dance styles. Ten pairs of dancers performed two different structured lessons of Salsa dance, including Typical Salsa and Rueda de Casino lessons, and a non-structured Salsa dance at a night club. Physiological responses (i.e., percent of heart rate reserve; %HRR) were continuously assessed and perceived exertion and affective valence were rated every 15 min throughout the trials. %HRR responses differed between the Salsa dance styles (%HRR from 41.3 to 51.9%), and participants were dancing at intensities near their ventilatory threshold. Specifically, Typical Salsa lesson elicited lower %HRR responses than Rueda de Casino lesson (p < 0.05), but similar %HRR responses to Salsa dance at a night club condition (p > 0.05). Surprisingly, exertional (from 8 to 11) and affective (from +3 to +5) responses were unaffected by Salsa dance styles (p > 0.05). These data support that different Salsa dance styles provide physiological stimuli adequate to promote health and fitness benefits, and perhaps more importantly, produce pleasurable experiences, which in turn might lead to an increase in adherence to Salsa dancing which likely provides exercise-like health benefits.     

Psychophysiological investigations on transcendental meditation

Two experiments were conducted to evaluate the psychophysiological changes reported to occur during the practice of transcendental meditation. In Experiment I, 47 volunteers solicited from the community were randomly assigned to transcendental meditation (TM), Benson's relaxation response (BRR), or no treatment (NT) instruction. Respiration rate, heart rate, electromyogram, electroencephalogram, and skin conductance level were recorded during the practice of each technique, approximately 1 week after terminating instruction. The results indicate that while BRR, TM, and NT exhibited different physiological patterns, none of the techniques showed a clear superiority in reducing tonic physiological arousal. In Experiment II, 30 volunteers with previous experience were assigned to one of three groups based on their meditating experience (range 16–96 months). The same physiological signals as in Experiment I were also recorded in this experiment during TM practice. The results suggest that individuals with 1.5 years of meditation experience exhibited physiological arousal levels similar to those seen in persons with over 5 years' experience.This article is based on the author's dissertation submitted to the University of Georgia in partial fulfillment of requirement for the Ph.D. degree. The author would like to thank Dr. L. J. Peacock for his guidance and to acknowledge Student International Meditation Society for their assistance.     

Adaptation of Pseudomonas fluorescens to Low Levels of Water Activity Produced by Different Solutes

A culture of Pseudomonas fluorescens which grew at a minimal a_w of 0.97 in a glucose-salts broth adjusted to that level with NaCl, KCl, or glucose, and at a_w 0.9725 with Na₂SO₄, was adapted to grow at lower a_w levels produced by these solutes. Adaptation to growth at a low a_w produced by means of one solute did not necessarily result in growth at that a_w when another solute was employed to lower the a_w. The culture adapted to grow at a_w 0.9650 produced by addition of glucose could grow equally well in broth adjusted to that a_w with NaCl or KCl, but not Na₂SO₄. NaCl and KCl permitted growth at the lowest a_w level (0.9625), and the culture adapted in KCl did equally well in NaCl.     

EEG Correlates of the Psychological Adaptation Potential of a Personality

In a group of 68 adults of both sexes, we examined correlations between estimates of the psychological adaptability of an individual (diagnosed using a multilevel personality questionnaire, MPQ) and spectral powers, SPs, of the frequency components (rhythms) of background EEG recorded in the resting state (leads C3 and C4 according to the 10–20 system). Despite high individual variability within the group, indices by the scale “communicative potential” demonstrated significant correlation with the SP of the θ rhythm, while estimates of the moral normativity correlated with the SPs of the α and β1 rhythms. Subgroups of the persons classified according to the level of the integral adaptation capability (personality’s adaptation potential) differed from each other in the mean estimates of interhemisphere asymmetry of the α rhythm; this index was higher in subjects with the medium/high level of adaptability. The correlations observed are, most probably, determined by the fact that both the level of psychological adaptability of the personality and the EEG amplitude parameters depend significantly on genetic (neurochemical, in particular) factors. Such peculiarities of the neurodynamic constitution of the individual are probably determined, to a considerable extent, by the specificities of organization and functioning of a few neurotransmitter (aminergic, in particular) and neurohumoral systems.     

A Concept of Educational Activity for Schoolchildren

About two years ago, on a cool Southern California day, Vasili Davydov addressed a group of social scientists at the University of California, San Diego. He began his talk with a paradox. He had come, he said, to tell us about educational activity. He promised to exhibit principles that promote educational activity, and applied programs deriving from those principles. Then he laughed. "But you'll never see educational activity in the school," he said, and laughed again.     

Breeding for Yield Potential and Stress Adaptation in Cereals

The need to accelerate breeding for increased yield potential and better adaptation to drought and other abiotic stresses is an issue of increasing urgency. As the population continues to grow rapidly, the pressure on resources (mainly untouched land and water) is also increasing, and potential climate change poses further challenges. We discuss ways to improve the efficiency of crop breeding through a better physiological understanding by both conventional and molecular methods. Thus the review highlights the physiological basis of crop yield and its response to stresses, with special emphasis on drought. This is not just because physiology forms the basis of proper phenotyping, one of the pillars of breeding, but because a full understanding of physiology is also needed, for example, to design the traits targeted by molecular breeding approaches such as marker-assisted selection (MAS) or plant transformation or the way these traits are evaluated. Most of the information in this review deals with cereals, since they include the world's main crops, however, examples from other crops are also included. Topics covered by the review include the conceptual framework for identifying secondary traits associated with yield potential and stress adaptation, and how to measure these secondary traits in practice. The second part of the review deals with the real role of molecular breeding for complex traits from a physiological perspective. This part examines current developments in MAS and quantitative trait loci (QTL) detection as well as plant transformation. Emphasis is placed on the current limitations of these molecular approaches to improving stress adaptation and yield potential. The essay ends by presenting some ideas regarding future avenues for crop breeding given the current and possible future challenges, and on a multidisciplinary approach where physiological knowledge and proper phenotyping play a major role.     

Effect of Light Intensity on Adaptation of Dunaliella to Very High Salt Concentrations

Light intensity was found to have a strong effect on the adaptationto high salt concentrations of a green microalga, Dunaliellaparva, normally grown at low and medium salt concentrations.At high light intensities (200 µmol m^–2 s^–1)the cell glycerol content increased in parallel with an increasein external salt concentration; protein synthesis and cell divisioncontinued with no period of arrest. At low light intensitiesno glycerol synthesis occurred as the external salt concentrationwas raised; protein synthesis and cell division were equallyarrested. The importance of high light intensity during theinitial phase of increase of salt concentration was demonstratedand was found to be a requirement for protein synthesis andcell division. In experiments designed to discover the effectof light intensity on cells growing in media in which the saltconcentration was kept constant, it was confirmed that the lightintensity needed for growth increases as the salt concentrationof the medium is increased. Key words: Dunaliella, salt concentration, light intensity, growth rates     

Ethanol-induced Adaptation of Alcohol Dehydrogenase Activity in Rat Brain

ALTHOUGH the presence of alcohol dehydrogenase (ADH) in cerebral tissue has been established¹, a physiological role for such a brain ethanol-oxidizing system has been unclear. The brain may be more biochemically adaptive than was once thought²; thus, it seemed possible that brain ADH may be substrate-induced. We now report that significant elevations of brain ADH activity occur in alcohol-imbibing rats; no changes from control values were found in liver ADH, liver aldehyde dehydrogenase (AldDH), or brain AldDH activities.     

冬眠动物骨骼肌生理适应及机制的研究进展

非冬眠动物的骨骼肌在废用条件下会发生明显的萎缩。冬眠动物在历经数月的冬眠期骨骼肌废用后,仍能保持较完整的形态结构与良好的收缩功能,成为天然的抗废用性肌萎缩动物模型。探明冬眠动物骨骼肌对废用的生理适应机制,是生理生态学领域的重要课题之一。本文从形态结构、肌纤维类型和收缩功能等方面综述了冬眠动物对冬眠期骨骼肌废用状态的生理适应,并从蛋白质代谢、生长与分化的调控、代谢类型的调控、氧化应激以及线粒体结构与氧化能力等方面分析了冬眠期骨骼肌生理适应的可能机制。