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.     

Inhibition of Auxin Polar Transport Affecting the Model of Leaf Growth and Development

Tobacco (Nicotiana tabacum L. cv. Gexin No. 1) leaf slices were cultured in MS medium with different concentrations of auxin polar transport inhibitors (2, 3, 5-triiodobenzoic acid (TIBA), trans-cinnamic acid (CA), and 9-hydooxyflurence-9-carboxylic acid (HFCA)) and their effects on bud formation were observed. Although the effective concentrations vary with different inhibitors, all of them induced the formation of trumpet-shaped leaves. The frequencies of trumpet-shaped leaves were increased with the concentrations of inhibitors in media, and it was up to 82.1% when cultured in the medium containing 7.5 mg/L TIBA. The trumpet-shaped leaves were formed in different sites of the adventitious buds. These results indicated that inhibition of auxin polar transport could affect the morphogenesis of leaves, so the polar transport of auxin is essential for the bilateral symmetry of leaf growth.     

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.     

Growth Inhibition by Lysine Plus Threonine: Comparative Inhibition Profiles between Floury-a and Normal Maize Embryos

Lysine and threonine, either alone or in combination, were testedfor their effects on growth of floury- mutant and DY normalembryos of maize in culture. At 1 mM of lysine, no inhibitoryeffect was observed on either type of embryo, although at 2.5mM slight inhibitions were observed, principally on the rootand shoot lengths. The inhibition profiles by threonine from0.5 to 2.5 mM were similar to those by lysine only in the floury-embryos; in the normal DY embryos, threonine produced a markedinhibition, especially on the root and shoot length. In conjunctinhibition experiments, the profile of inhibition obtained forfloury- embryos by variable levels of lysine with a constantlevel of threonine were always identical to that by variablelevels of threonine with a constant lysine level. On the otherhand, in the normal DY embryos, the extent of the inhibitoryeffect by variable levels of lysine with a Constant threoninelevel was much greater than that by variable levels of threoninewith a constant lysine level. The involvement of homoserinedehydrogenase of the floury- embryo in the lesser sensitivityfor feedback inhibition by threonine is discussed. ¹ Paper No. 112 of the Instituto Fitot?cnico de Santa Catalina,Facultad de Agronomia, Universidad Nacional de La Plata. (Received July 7, 1981; Accepted December 21, 1981)     

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.     

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.     

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.     

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.     

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.     

Inhibition of Growth by Amber Suppressors in Yeast

Strains of the yeast Saccharomyces cerevisiae that contain highly efficient amber (UAG) suppressors grow poorly on nutrient medium, while normal or nearly normal growth rates are observed when these strains lose the supressors or when the suppressors are mutated to lower efficiencies. The different growth rates account for the accumulation of mutants with lowered efficiencies in cultures of strains with highly efficient amber suppressors. Genetic analyses indicate that one of the mutations with a lowered efficiency of suppression is caused by an intragenic mutation of the amber supressor. The inhibition of growth caused by excessive suppression is expected to be exacerbated when appropriate suppressors are combined together in haploid cells if two suppressors act with a greater efficiency than a single suppressor. Such retardation of growth is observed with combinations of two UAA (ochre) suppressors (Gilmore 1967) and with combinations of two UAG suppressors when the efficiencies of each of the suppressors are within a critical range. In contrast, combinations of a UAA suppressor and a UAG suppressor do not affect growth rate. Apparently while either excessive UAA or excessive UAG suppression is deleterious to yeast, a moderate level of simultaneous UAA and UAG suppression is not.     

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.     

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.     

右侧输卵管同时合并左侧卵巢妊娠一例暨文献复习

目的:总结输卵管合并卵巢妊娠的诊治经验教训和治疗方法。方法:回顾性分析我院2010年11月9日入院右侧输卵管同时合并左侧卵巢妊娠患者临床资料,B超检查,急诊腹腔镜探查术并送病理组织检查。结果:行右侧输卵管切除术+左侧卵巢囊肿剥除术+粘连分解术后病检结果为:(右输卵管)腔内变性绒毛及滋养细胞,符合异位妊娠;(左卵巢囊肿)羊膜、绒毛及滋胚叶细胞,符合异位妊娠。术后3、6和8天患者血HCG浓度水平分别为19.61ng/ml、4.47ng/ml和1.84ng/ml,术后顺利恢复出院。结论:输卵管合并卵巢妊娠发生较为罕见,极易漏诊和误诊,及时行腹腔镜探查术是有效的诊治手段。