An Estimate of the Extent of Folding of Nucleosomal DNA by Laterally Asymmetric Neutralization of Phosphate Groups

Abstract

We attempt quantitative implementation of a previous suggestion that asymmetric charge neutralization of DNA phosphate groups may provide part of the driving force for nucleosome folding. Polyelectrolyte theory can be used to estimate the effective compressive force acting along the length of one side of the DNA surface when a fraction of the phosphate groups are neutralized by histones bound to that side. A standard engineering formula then relates the force to the bending amplitude caused by it. Calculated bending amplitudes are consistent with the curvature of nucleosomal DNA and the overall extent of charge neutralization by the histones. The relation of the model to various aspects of nucleosome folding, including the detailed path of core-particle DNA is discussed. Several other DNA-protein complexes are listed as examples of possible asymmetric charge-induced bending.     

When Right Feels Left: Referral of Touch and Ownership between the Hands

Feeling touch on a body part is paradigmatically considered to require stimulation of tactile afferents from the body part in question, at least in healthy non-synaesthetic individuals. In contrast to this view, we report a perceptual illusion where people experience “phantom touches” on a right rubber hand when they see it brushed simultaneously with brushes applied to their left hand. Such illusory duplication and transfer of touch from the left to the right hand was only elicited when a homologous (i.e., left and right) pair of hands was brushed in synchrony for an extended period of time. This stimulation caused the majority of our participants to perceive the right rubber hand as their own and to sense two distinct touches – one located on the right rubber hand and the other on their left (stimulated) hand. This effect was supported by quantitative subjective reports in the form of questionnaires, behavioral data from a task in which participants pointed to the felt location of their right hand, and physiological evidence obtained by skin conductance responses when threatening the model hand. Our findings suggest that visual information augments subthreshold somatosensory responses in the ipsilateral hemisphere, thus producing a tactile experience from the non-stimulated body part. This finding is important because it reveals a new bilateral multisensory mechanism for tactile perception and limb ownership.     

Aging Affects the Mental Rotation of Left and Right Hands

Background

Normal aging significantly influences motor and cognitive performance. Little is known about age-related changes in action simulation. Here, we investigated the influence of aging on implicit motor imagery.

Methodology/Principal Findings

Twenty young (mean age: 23.9±2.8 years) and nineteen elderly (mean age: 78.3±4.5 years) subjects, all right-handed, were required to determine the laterality of hands presented in various positions. To do so, they mentally rotated their hands to match them with the hand-stimuli. We showed that: (1) elderly subjects were affected in their ability to implicitly simulate movements of the upper limbs, especially those requiring the largest amplitude of displacement and/or with strong biomechanical constraints; (2) this decline was greater for movements of the non-dominant arm than of the dominant arm.

Conclusions/Significance

These results extend recent findings showing age-related alterations of the explicit side of motor imagery. They suggest that a general decline in action simulation occurs with normal aging, in particular for the non-dominant side of the body.     

Sex Differences and Activity of the Left and Right Brain Hemispheres

The problem is reviewed of sex differences and the brain organization of the visual-spatial and verbal-cognitive functions both in adults and in the 5–15-year old children. Characteristic of men are the integral strategy of the face image recognition, specialization of the right hemisphere for visual-spatial functions, and the tonic inhibitory effect of the right hemisphere on the left one. Typical of women are the fragmented type of the image recognition, the equality of the brain hemispheres functions at the unfamiliar face recognition, and predominance of the left hemisphere by accuracy of the object localization in the visual field. It is possible that the general strategy of the recognition in women is not realized due to the right hemisphere submitted to the interfering effect of the left hemisphere. Analysis of sex differences in distribution of verbal functions shows that the capability for the verbal learning at the age of 5 years and older is higher in girls than in boys. Such capability seems to be accounted for by the superiority of the left hemisphere in girls in this type of its activity and by its earlier development and maturation. The phenomenon of semantic paralexia appearing more often in boys is accounted for by inclusion of lexical-semantic fields of the right hemisphere symmetric areas in the verbal-cognitive activity There are reasons to believe that the higher capability in girls for the verbal learning is mainly due to processes of the auditory-verbal integration within the limits of the left hemisphere, whereas this verbal ability in boys depends on the relative predominance of the interhemispheric connections.     

Inhibition of Plant Root Growth by Enzymes and Histones

It has been shown previously that root growth can be inhibited by basic, animal proteins. In an effort to see if a plant histone was more efficacious than the animal protein, roots were grown in the presence of wheat histone. Otber basic polymers were also tested. Polycations, including salmine, lysozyme, ribonuclease, wheat germ histone, thymus histone and polylysine inhibit root elongation of barley and wheat. Polyglutamate and lysylglycine at comparable weight concentrations are not inhibitory. No difference in the efficacy of tbe plant and the animal histones could be found with either plant, which suggests that the action is non-specific. Growth of roots inhibited by histone, trypsin, or lysozyme can resume after removal of the polycation. The mechanism whereby polycations influence root growth is not known, but it is clear that the polymeric state of ionic functional groups is of paramount importance in the binding of the polycations to cell surfaces.     

Greater Activity in the Frontal Cortex on Left Curves: A Vector-Based fNIRS Study of Left and Right Curve Driving

ObjectivesIn the brain, the mechanisms of attention to the left and the right are known to be different. It is possible that brain activity when driving also differs with different horizontal road alignments (left or right curves), but little is known about this. We found driver brain activity to be different when driving on left and right curves, in an experiment using a large-scale driving simulator and functional near-infrared spectroscopy (fNIRS).ResultsUnder driving conditions, there were no sites where cerebral oxygen exchange increased significantly more during right curves than during left curves (p > 0.05), but cerebral oxygen exchange increased significantly more during left curves (p < 0.05) in the right premotor cortex, the right frontal eye field and the bilateral prefrontal cortex. Under non-driving conditions, increases were significantly greater during left curves (p < 0.05) only in the right frontal eye field.ConclusionsLeft curve driving was thus found to require more brain activity at multiple sites, suggesting that left curve driving may require more visual attention than right curve driving. The right frontal eye field was activated under both driving and non-driving conditions.     

Growth of Yeasts on n-Alkanes: Inhibition by a Lactonic Sophorolipid Produced by

The effects of amino acids on IMP production were examined with a mutant strain, KY10895, derived from Corynebacterium ammoniagenes KY13374. l-Proline improved the productivity of IMP more than any other amino acid. The optimum concentration of l-proline for IMP production was 1–2% and the IMP productivity was about 70% more than that in the control medium. The effects of l-proline analogs on IMP production were also examined with the mutant KY10895. DL-3,4-Dehydroproline inhibited IMP production. Mutants resistant to growth inhibition by dl-3,4-dehydroproline were derived from strain KY10895. Among mutants thus obtained, strain H-7335 had the highest productivity. The intracellular concentrations of l-proline in strain H-7335 were higher than those of the parental strain, KY10895. These findings indicated that an increase in intracellular l-proline was linked with an increase of IMP productivity and strengthening the l-proline synthesis of a strain was an effective method for obtaining a hyper-producer of IMP.     

Correlative Growth in Seedlings of Phaseolus vulgaris L. : Inhibition of Stem Growth by the Primary Leaves

Primary leaves of one-week-old seedlings of dwarf beans effectivelyinhibit stem elongation either in natural daylight or in continuousdarkness. Stem elongation is promoted by exogenous gibberellicacid and kinetin and inhibited by indol-3-ylacetic acid (IAA)or abscisic acid, and it is suggested that IAA is the inhibitorysubstance emanating from the primary leaf blades which affectsthe growth of the stem.     

Inhibition of the Transsulfuration Pathway Affects Growth and Feather Follicle Development in Meat-Type Chickens

Cysteine is a nonessential amino acid in poultry nutrition. Poultry diets are deficient in cysteine, but the bird’s cysteine need is met through the transsulfuration pathway (TSP) where homocysteine is converted to cysteine: a process catalyzed by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH). Cysteine is also a major component of keratinized protein found in feathers, but the extent to which cysteine is involved in feather and skin development in poultry is unknown. We randomly assigned chicks to control and treatment (control diet plus 100?mg/kg body weight of propargylglycine which is an inhibitor of CTH) diets. The thickness of skin layers, primary feather follicle parameters, growth, and mRNA expression of CBS and CTH were measured. Inhibition of TSP corresponded with the upregulation of liver mRNA of both CBS and CTH and reduction in growth from 35 to 40 days of age. The epidermis thickness, feather follicle length, and diameter were reduced from 10 to 40 days of age. Incorporation of cysteine into keratinized protein may be more sensitive to the level of available cysteine than into nonkeratinized proteins. Thus, disruption of the TSP could affect the thermoregulatory ability of the bird.     

The Inhibition of Seedling Growth by Streptomycin Sulfate

The action of streptomycin sulfate (SS) on the growth of germinating seeds was investigated. It inhibited root growth more than shoot growth. Chemical analysis of roots indicated that nucleic acids decreased but their elution pattern from a column of methylated albumin kieselghur showed no qualitative differences. SS decreased the number of cells undergoing mitosis per root tip. This number was correlated with root length. One nM N⁵-benzyladenine reversed the effect of SS on both root length and mitosis. Thus the effect of SS appears specific to cell division. SS failed to affect oxidative phosphorylation in isolated mitochondria so its effect on cell division would not be secondary to the inhibition of energy conservation. It s possible inhibition of enzyme activity is selective since it also failed to affect RNase activity in vitro.     

Growth Inhibition of Rhodopseudomonas capsulata by Methylmercury Acetate

Growth of Rhodopseudomonas capsulata was inhibited in a bacteriostatic manner by as little as 10-minus 8 M methylmercury acetate (MeHgAc) in unsupplemented synthetic liquid medium or when cells were exposed to 8.0 nm of MeHgAc per mg of cell protein in a single exposure.     

Stimulation and Inhibition by Ethephon of Stem and Leaf Growth of Some Gramineae at Different Stages of Development

The effect of ethephon on the growth of leaves and stems ofP. pratensis, Agrostis sp., and A. sativa was investigated.The length of the leaves of all species as well as that of theinternodes of stems of vegetative tillers of Agrostis sp. andof stems of reproductive A. sativa plants was reduced. Epidermalcell length was unchanged or somewhat increased, indicatinga reduction in cell number. The rate of cell elongation maybe decreased, however. A reduction in cell length was observedin the internode of generative oat plants that just startedto elongate at the time of treatment. In vegetative tillers of P.pratensis and A. sativa ethephonpromoted growth of the internodes by increasing cell length.Cell number was little affected. GA3 also promoted internodegrowth, causing an increase in cell length as well as in cellnumber. Application of ethephon and GA3 together gave an additiveeffect on cell length but a reverse effect on cell number. Effects of ethephon were observed for 5 or more weeks aftertreatment. Ethylene production from plants of A sativa increased,but the extra production had already decreased by 90% after11 d. No stimulation of the ethylene production by the plantsother than from the breakdown of ethephon was observed.     

Growth Inhibition of Crithidia fasciculata by Serotoninergic and Adrenergic Drugs

SYNOPSIS. Growth of Crithidia fasciculata , a trypanosomatid flagellate known to contain epinephrine and serotonin, is sensitively inhibited by several adrenergically and serotoninergically reactive drugs such as dichloroisoproterenol, desipramine, and cyproheptidine. The pattern of sensitivity of Crithidia to these drugs is contrasted to the pattern of sensitivity of the ciliate Tetrahymena pyriformis.     

Inhibition of Soybean Cell Growth by the Adsorption of Rhizobium japonicum

Soybean cells in suspension culture were inhibited in their growth by mixed culture with Rhizobium japonicum 5033. Rhizobium cells had the ability to adsorb on the surface of soybean cells. Cell envelope prepared from Rhizobium by sonic oscillation inhibited the growth of soybean cells. The growth-inhibiting activity of the cell envelope was depressed by β-glucosidase, KIO₄, urea, sodium cholate, and Triton X-100, but was stable on heating at 120 C for 15 minutes. Adsorption of the cell envelope on soybean cells was depressed by only β-glucosidase. The sodium cholate-soluble fraction of the cell envelope had the growth-inhibiting activity. Results in this paper suggest that components of the Rhizobium cell surface cause the inhibition of soybean cell growth after the adsorption of the Rhizobium cell to the soybean cell.     

Inhibition of the Anaerobic Growth of Brochothrix thermosphacta by Lactic Acid

Brochothrix thermosphacta can grow aerobically in the presence of 210 mM l-lactate and anaerobically in its absence at pH values down to at least 5.5. Anaerobic growth is, however, inhibited by l-lactate, the concentration of undissociated lactic acid being the governing factor. Postrigor meat usually contains sufficient lactic acid to select against the anaerobic growth of B. thermosphacta. At least some Lactobacillaceae strains are more resistant to lactic acid and so their growth is favored on vacuum-packaged meat.     

Rapid Inhibition of Leaf Growth by Root Cooling in Wheat: Kinetics and Mechanism

Cooling of the roots was shown here to cause marked and rapidinhibition of leaf growth in wheat seedlings, as in some otherspecies. The root-shoot signal involved in this response wasinvestigated. Displacement transducers were used for the simultaneousmonitoring of leaf growth rate and leaf thickness in individualseedlings. Leaf water status was inferred from leaf thickness.Kinetics of changing water status were compared with those ofchanging leaf growth rate in the same seedling. Leaf water statuswas found to decline markedly beginning immediately after rootcooling. This occurs because cooling reduces the hydraulic conductivityof roots almost to zero. Apparent leaf growth rate was extremelysensitive to small changes in leaf water status, and the initialdecrease in leaf water status after root cooling was sufficientto cause cessation of leaf growth. Complications arising fromleaf elasticity and other sources were considered. Prolongedroot cooling caused a sustained depression in both leaf waterstatus and leaf growth rate. The effects of root cooling onleaf thickness and growth rate were completely prevented ifwater was made freely available to the shoot. It is thereforeconcluded that hydraulic factors (signals) can explain the short-and(at least in part) the medium-term effects of root cooling onleaf growth rate in wheat. Key words: Triticum durum L., leaf growth rate, hydraulic signals, root cooling