Structure of crambin in solution, crystal and in the trajectories of molecular dynamics simulations

The mechanisms of the three-dimensional crambin structure alterations in the crystalline environments and in the trajectories of the molecular dynamics simulations in the vacuum and crystal surroundings have been analyzed. In the crystalline state and in the solution the partial regrouping of remote intramolecular packing contacts, involved in the formation and stabilization of the tertiary structure of the crambin molecule, occurs in NMR structures. In the crystalline state it is initiated by the formation of the intermolecular contacts, the conformational influence of its appearance is distributed over the structure. The changes of the conformations and positions of the residues of the loop segments, where the intermolecular contacts of the crystal surroundings are preferably concentrated, are most observable. Under the influence of these contacts the principal change of the regular secondary structure of crambin is taking place: extension of the two-strand β structure to the three-strand structure with the participation of the single last residue N46 of the C-terminal loop. In comparison with the C-terminal loop the more profound changes are observed in the conformation and the atomic positions of the backbone atoms and in the solvent accessibility of the residues of the interhelical loop. In the solution of the ensemble of the 8 NMR structures relative accessibility to the solvent differs more noticeably also in the region of the loop segments and rather markedly in the interhelical loop. In the crambin cryogenic crystal structures the positions of the atoms of the backbone and/or side chain of 14–18 of 46 residues are discretely disordered. The disorganizations of at least 8 of 14 residues occur directly in the regions of the intermolecular contacts and another 5 residues are disordered indirectly through the intramolecular contacts with the residues of the intermolecular contacts. Upon the molecular dynamics simulation in the vacuum surrounding as in the solution of the crystalline structure of crambin the essential changes of the backbone conformation are caused by the intermolecular contacts absence, but partly masked by the structure changes owing to the nonpolar H atoms absence on the simulated structure. The intermolecular contact absence is partly manifested upon the molecular dynamics simulation of the crambin crystal with one protein molecule. Compared to the crystal structure the lengths of the interpeptide hydrogen bonds and other interresidue contacts in an average solution NMR structure are somewhat shorter and accordingly the energy of the interpeptide hydrogen bonds is better. This length shortening can occur at the stage of the refinement of the NMR structures of the crambin and other proteins by its energy minimizations in the vacuum surroundings and not exist in the solution protein structures.     

ON THE CAUSE OF THE INFLUENCE OF IONS ON THE RATE OF DIFFUSION OF WATER THROUGH COLLODION MEMBRANES. II

1. It had been shown in previous publications that when pure water is separated from a solution of an electrolyte by a collodion membrane the ion with the same sign of charge as the membrane increases and the ion with the opposite sign of charge as the membrane diminishes the rate of diffusion of water into the solution; but that the relative influence of the oppositely charged ions upon the rate of diffusion of water through the membrane is not the same for different concentrations. Beginning with the lowest concentrations of electrolytes the attractive influence of that ion which has the same sign of charge as the collodion membrane upon the oppositely charged water increases more rapidly with increasing concentration of the electrolyte than the repelling effect of the ion possessing the opposite sign of charge as the membrane. When the concentration exceeds a certain critical value the repelling influence of the latter ion upon the water increases more rapidly with a further increase in the concentration of the electrolyte than the attractive influence of the ion having the same sign of charge as the membrane. 2. It is shown in this paper that the influence of the concentration of electrolytes on the rate of transport of water through collodion membranes in electrical endosmose is similar to that in the case of free osmosis. 3. On the basis of the Helmholtz theory of electrical double layers this seems to indicate that the influence of an electrolyte on the rate of diffusion of water through a collodion membrane in the case of free osmosis is due to the fact that the ion possessing the same sign of charge as the membrane increases the density of charge of the latter while the ion with the opposite sign diminishes the density of charge of the membrane. The relative influence of the oppositely charged ions on the density of charge of the membrane is not the same in all concentrations. The influence of the ion with the same sign of charge increases in the lowest concentrations more rapidly with increasing concentration than the influence of the ion with the opposite sign of charge, while for somewhat higher concentrations the reverse is true.     

Ontogenetic switchover in Bacillus subtilis. II. The dynamics of the stationary phase processes during growth under conditions of catabolite repression]

To reveal the pecularities of the growth under the conditions of catabolite repression (medium 2) of Bacillus subtilis and the mutants obtained, the investigations of dynamics of the following processes were carried out: alteration of the pH of the culture exhaustion of glucose in the medium, appearance of the activity of both aconitase in the cells and extracellular metal- and serine proteases in the supernatant, and the appearance of the thermoresistant spores. The following features were observed during the growth under the conditions of catabolite repression: 1. Bacillus subtilis WB 746 and cgs mutants: the death of the main part of the culture after the Iogarithmic phase of growth (LPG), the presence of the secondary LPG of the survived cells which have the increasing activity of aconitase, the appearance and sharp increase in the extracellular serine protease activity 6 hours before thermoresistant spore formation. In the case of cgs mutants the activity of metal proteases appears and increases during the secondary LPG; 2. In the culture of cgl mutants the pH is lowered to 5.1 at the end of the LPG and after the glucose exhaustion the death of almost all the culture follows; 3. cgr mutants: a comparatively high activity of aconitase in the cells is found by the time of the early LPG, and at the end of the LPG the activity of both metal- and serine proteases appear in the supernatant of the culture and the secondary induction of the serine protease activity 6 hours before thermoresistant spore formation is observed. The serine protease activity found in the supernatant before and after the secondary induction of the enzyme belongs to the identical protein. During the stationary phase of the growth of cgr mutants, the high rate of 3H-uridine incorporation into the RNA molecules which have the electrophoretic mobility of mRNA was observed. The sporulation of Bac. subtilis strains under investigation, except cgl mutants, occurs when the culture has reached the definite state: the alkaline pH, the presence of the aconitase activity in the cells and the induced activity of serine protease.     

Resonant excitation of the magnetosphere by stochastic and unsteady hydromagnetic waves

The effect of the magnetospheric MHD cavity on the excitation of the magnetosphere by stochastic and unsteady hydromagnetic waves incident from the solar wind is investigated theoretically by using a one-dimensional nonuniform model of the medium. It is shown that most of the energy of stochastic waves is reflected from the magnetopause and that the only waves that penetrate into the magnetosphere are those with frequencies in narrow spectral ranges near the eigenfrequencies of the cavity. These waves lead to steadystate excitation of the eigenmodes of the cavity, the energy of which is determined by the spectral density of the energy flux of the incident waves at the corresponding eigenfrequencies. The energy of the eigenmodes penetrates through the opacity barrier in the vicinity of the Alfvén resonance points (each corresponding to a particular mode), where the perturbation amplitude is sharply amplified, so the total energy localized close to the Alfvén resonance point is much higher than the total energy of the corresponding eigenmode. In the vicinities, the perturbation energy is dissipated by the finite conductivity of the ionosphere, the dissipation power being equal to the energy flux of the incident waves that penetrates into the magnetosphere. The case of unsteady waves is analyzed by considering a wave pulse as an example. It is shown that most of the energy of the wave pulse is reflected from the magnetopause. The portion of the incident perturbation that penetrates into the magnetosphere leads to unsteady excitation of the eigenmodes of the magnetospheric cavity, which are then slowly damped because part of the energy of the cavity is emitted through the magnetopause back to the solar wind while the other part penetrates into the vicinities of the Alfvén resonance points. In the vicinities, the perturbation is an Alfvén wave standing between magnetically conjugate ionospheres and its energy is dissipated by the finite conductivity of the ionosphere at a rate slower than the damping rate of the eigenmodes of the cavity.     

Detection of intranuclear forces by the use of laser optics during the recovery process of elongated interphase nuclei in centrifuged protenemal cells ofAdiantum capillus-veneris

For the direct investigation of intranuclear dynamics in living cells, extremely deformed nuclei of basipetally centrifuged protonemal cells of the fernAdiantum capillus-veneris were manipulated by the laser trap and the laser scalpel. Whereas the nucleolus was tightly fixed at the central position inside the non-centrifuged nucleus and proved to be immovable by the optical trap, it could easily be trapped and moved towards three directions inside the bubble-like terminal widening of the basal thread-like extension of centrifuged nuclei. Due to the connection of the nucleolus to the chromatin inside the nuclear thread (NT), moving was not possible against the direction of the nuclear apical main body. Nucleoli in recovered nuclei were again immovable, thus indicating the presence of a dynamic nucleolar anchoring system inside the nucleus. When the nucleolus in the bubble was arrested during the thread shortening process by the optical trap, the acropetal movement of the bubble continued. Probably due to dragging forces, some nucleoli became stretched, and a thick strand of a still unknown composition stretched between the nucleolus and the insertion site of the shortening NT. To assess whether the shrinking of the nuclear envelope (NE) and the shortening of the chromatin inside the NT were independent processes, the chromatin above the bubble was cut inside the NT by the laser scalpel. After severance, a gap between the nucleolus and the end of the chromatin strand in the NT indicated the shortening of the chromatin inside the NT. From these findings it was concluded that a shortening force was existing in the chromatin of the NT and that probably no physical link existed between the chromatin and the NE.     

中国树鼩下丘脑视上核和室旁核内加压素能和催产素能神经元的形态计量学分析

采用免疫组织化学ＰＡＰ／ＤＡＮ－镍加强技术和形态计量法研究了中国树鼩下丘脑加压素（ＶＰ）能和催产素（ＯＴ）能视上核主部（ＳＯＮｐ）、视上核交叉后部（ＳＯＮｒ）和室旁核（ＰＶＮ）的平均矢轴长度,ＳＯＮｐ,ＳＯＮｒ和ＰＶＮ内ＶＰ能和ＯＴ能神经元胞体截面积的平均值;ＳＯＮｐ,ＳＯＮｒ和ＰＶＮ的ＶＰ能和ＯＴ能神经元总数;各校团的各个系列节段内ＶＰ能和ＯＴ能神经元的比较计数。发现,ＳＯＮｐ前１／３部分ＯＴ能神经元明显多于ＶＰ能的,而后２／３部分则相反;ＳＯＮｒ前２／３部分ＶＰ能神经元明显多于ＯＴ能的,而后１／３部分两者差别不明显;ＰＶＮ前２／３部分ＯＴ能神经元明显多于ＶＰ能的,而后１／３部分则相反。本文就中国树下丘脑ＳＯＮ和ＰＶＮ内ＶＰ能和ＯＴ能神经元的形态计量学资料与大鼠的进行了比较。     

黑河中下游绿洲生态安全评价

生态安全包括自然生态安全、经济生态安全和社会生态安全 ,尤指自然和半自然生态系统的安全 ,即生态系统完整性和健康的整体水平反映。生态安全是维护地区或国家乃至全球的生态环境不受威胁的状态 ,能为整个生态经济系统的持续发展提供生态保障。从水安全、土地安全、经济社会安全出发 ,选取水资源量供需比、地表水质量、地下水埋深和地下水矿化度 4种水安全评价指标 ;土地人口承载度、林地覆盖率、草地载畜度、绿洲面积变化率、绿洲土地沙化率、绿洲土地盐碱化率和抗灾度等 7种土地安全评价指标 ;人均 GDP产值、单位面积农业生产总值、农民人均纯收入、绿洲人口密度、城市化率和文明度等经济社会安全评价指标 ;共计 17项 ,建立了绿洲生态安全评价综合指标体系。然后 ,应用综合评价法、层次分析法和 GIS等多种方法与手段 ,在绿洲尺度上对黑河干流中下游地区的张掖、临泽、高台、鼎新和额济纳 5个绿洲进行绿洲生态安全综合评价。评价结果显示 :自黑河中游至下游 ,各个绿洲的生态安全状况依次降低 ,最下游的额济纳绿洲生态安全仅为 4级的差状态。其中 ,水安全是关键 ,土地安全是载体 ,经济社会安全是保障 ,以上几方面相互关联 ,共同作用导致绿洲的生态安全综合水平。     

L’étude des conditions d’habitabilité des établissements préhistoriques : à propos des amas coquilliers mésolithiques de la région cantabrique occidentale (Nord de l’Espagne)

We show the methodology we followed in order to reliably estimate a factor that, to our judgement, is fundamental for the assessment of the characteristics of a prehistoric settlement: the conditions of exposure to the sun. This methodology is applied to the study of Mesolithic shell middens in the North of Spain, with the aim to introduce a new kind of information in the debate about the meaning of shell middens. Throughout this century, different ways to understand the behaviour these remains conceal have been proposed. Our thesis with regard to it, presented in this paper, is based on the observation of a series of variables, among which we can find the exposure to the sun the settlements undergo. We therefore show in the last part of the paper, how to join the information from the proposed analysis with the other data subsequent from the study of other variables such as the environmental conditions prevailing during the period of formation of the sites; the situation of the settlements; the location of the remains in the caves; the entity of the occupations; and the energy spent on the transportation of the aquatic resources from the coast towards the places where their rests are found nowadays. In short, we propound a methodology for the study of one of the variables that falls upon the habitability of a prehistoric settlement and we point out the contribution that the incorporation of an analysis of this kind means for the research of Mesolithic shell middens in the North of Spain.     

Quantitative-morphometric and functional-anatomical studies on the locomotor apparatus of athletes. IV. Discussion, resume and literature

The locomotor system of 155 athletes from 3 athletic disciplines was examined, and the data of 20 anthropometrical measurements and the results for the corresponding disciplines were recorded subjected to a multivariate morphometrical analysis with the following aim: 1. To evaluate the morphological and functional-anatomical criteria of the locomotor system which quantified the variation differences in the body composition of the athletic groups, and which indicated a quantifiable functional-anatomical relationship between the variation in the body composition and the result in the corresponding disciplines. 2. To show the bivariate relationship between the morphological parameter and the results in the corresponding disciplines, and furthermore to evaluate the amount of result-increasing or result-decreasing components in a morphological variable. 3. To analyse the morphological variation of the 20 body composition variables and the corresponding results in the disciplines by means of factor analysis. This is achieved by the use of multivariate methods to analyse the variation in the athlete's body composition and the result-influencing-components. The following results were obtained: 1. There are partly pronounced morphological differences between the 3 athletic groups, quantified by discriminant functions. The differences in the locomotor system were reduced to 2 independent axes of variation, with one axis being identified as the general size variation between the 3 groups, and the other as the difference in the variation of the degree of strength of the musculature of the trunk and the limbs by considering the length and breadth measurements. For both canonical axes, the shotputters have above-average high canonical numbers compared to the other 2 groups. The sprinters and long jumpers show conformity in the general size variation of the locomotor system, but they differ in the second axis. Whilst in both groups the lower limbs are similarly constituted in form, shape and size, the canonical values of the trunk and the upper limbs of the sprinters are higher. In this respect, they tend more towards the shot-putter group. The morphological differences obtained for the athlete's locomotor system are functional-anatomically related to the corresponding athletic disciplines. 2. In almost every case, the regression functions for the shot-putters show an approximately linear relationship between the morphological variables and the result of the shot-putt. The quadratic and cubic regression functions only deviate slightly from the linearity, i.e. the result will be altered depending on the height and size of the body composition (within the possible range of biological variation). On the other hand, the sprinting result, either increased or decreased, is determined by a limited morphological variation of the parameter of the locomotor system...     

The diagnostic of membranes' state after exposure of gamma-radiation of small doses

There are the results of experimental research of the change of membranes' conditions under the action of gamma-radiation using the method of following membranes' electroporation of the accurate impulse of the electrical field for the analysis of defects after the action of gamma-radiation. As of the research material the suspension of erythrocytes was used. It was shown that the velocity of decreasing of the erythrocytes in the case of combined action of gamma-radiation and the impulse of the electrical field is more than the sum of such velocities in the case of the action of the factors separately. The method of the electroporation of the accurate impulse of the electircal field is obvious for the practicaland the analytical research of membranes' defects.     

海金沙胚胎发育的研究

利用石蜡切片法研究了海金沙胚胎发育过程。合子的第一次分裂面垂直于颈卵器的长轴,产生两个相等的子细胞,靠近颈卵器颈部的营养器官原始细胞和远离颈部的基足原始细胞。前者发育成子代孢子体的营养器官,后者发育成基足。胚胎在32细胞阶段后,第一叶顶端细胞与第一根顶端细胞几乎同时发生。第一叶突出帽状体之后,由第一叶基部保留下来的茎干顶端细胞产生第二叶。据营养器官的形态结构判断,在海金沙胚胎发育中最早出现的营养器官是叶和根。     

VASCULAR SYSTEM OF THE FLORET OF LEERSIA VIRGINICA (GRAMINEAE-ORYZOIDEAE)

The vascular system of the floret of Leersia is unified yet is segmented according to the appendages it serves. The rachilla at the floret base contains a collateral bundle related to the median trace of the lemma. The palea median trace joins the posterior of this bundle in the rachilla as the lemma laterals merge with the anterior. Although the stamen traces enter at the flanks of this rachilla bundle, they do not become fully incorporated into the system until near the floret base where the rachilla bundle, lemma laterals, and palea laterals converge. Traces from the lodicules attach to the anterior of the stamen traces. The base of the vascular system of the pistil, the pistil plexus, attaches tenuously by a bundle to the lower system between the entrance of the stamen traces. A bundle from each style attaches near the anterior of the pistil plexus below the level where the posterior of the pistil plexus rises, as the placental bundle, to merge with the ovule. Characteristics of the vascular system of Leersia, such as the relative discreteness of the staminal and stylar traces and the lack of both the anterior pistil bundle and the xylem discontinuity, are useful for delimiting the Oryzoideae from the Festucoideae.     

Stereometric observations on the hypothalamic neurosecretory system of the spotted owlet, Athene brama Temminck, in total preparations.

The configuration of the HNS of the spotted owlet, Athene brama Temminck, was studied by employing the bulk-staining technique. This enabled a three-dimensional view of the HNS. The neurons of the SON are distributed into three divisions, namely, the preoptic, median and lateral. The PVN is U-shaped; the distal portion of the arms of the U extends laterally to form the lateral division of the PVN, which remains in continuity with the lateral division of the SON. The periventricular division of the PVN joins ventrally the median division of the SON. Unlike in the passerine birds, in the spotted owlet the PVN is more prominently developed than the SON. Since the axonal pathways are not stained, the proximal portion of the hypothalamo-hypophysial tract could not be demonstrated in bulk-stained preparations. Hence it was not possible to trace with certainty the origin of the axonal terminations in the ME and in the NL. Anterior of the ME, the tract branches into two; one branch enters the zona externa to the ME and the other is continued into the NL. The ME is divisible into an AF-positive anterior region and an AF-negative posterior region. The NL is saccular and heavily loaded with the NSM. Studies on the HNS of the spotted owlet by the bulk-staining technique reveal that the general configuration of the system is comparable to that of the HNS of birds studied previously.     

3D finite element simulation of the opening movement of the mandible in healthy and pathologic situations

One of the essential causes of disk disorders is the pathologic change in the ligamentous attachments of the disk-condyle complex. In this paper, the response of the soft components of a human temporomandibular joint during mouth opening in healthy and two pathologic situations was studied. A three-dimensional finite element model of this joint comprising the bone components, the articular disk, and the temporomandibular ligaments was developed from a set of medical images. A fiber reinforced porohyperelastic model was used to simulate the behavior of the articular disk, taking into account the orientation of the fibers in each zone of this cartilage component. The condylar movements during jaw opening were introduced as the loading condition in the analysis. In the healthy joint, it was obtained that the highest stresses were located at the lateral part of the intermediate zone of the disk. In this case, the collateral ligaments were subject to high loads, since they are responsible of the attachment of the disk to the condyle during the movement of the mandible. Additionally, two pathologic situations were simulated: damage of the retrodiscal tissue and disruption of the lateral discal ligament. In both cases, the highest stresses moved to the posterior part of the disk since it was displaced in the anterior-medial direction. In conclusion, in the healthy joint, the highest stresses were located in the lateral zone of the disk where perforations are found most often in the clinical experience. On the other hand, the results obtained in the damaged joints suggested that the disruption of the disk attachments may cause an anterior displacement of the disk and instability of the joint.     

A general framework for the statistical exploration of the ecological niche

We propose a new statistical framework for the exploratory analysis of the ecological niche, the “General niche-environment system factor analysis” (GNESFA). The data required for this analysis are (i) a table giving the values of the environmental variables in each environment unit (EU, e.g., the patches of habitat on a vector map), (ii) a set of weights measuring the availability of the EUs to the species (e.g., the proportion of the study area covered by a given patch), and (iii) a set of utilization weights describing the use of the EUs by the focal species (e.g., the proportion of detections of the species in each patch). Each row of the table corresponds to a point in the multidimensional space defined by the environmental variables, and each point is associated with two weights. The GNESFA searches the directions in this space where the two weight distributions differ the most, choosing one distribution as the reference, and the other one as the focus. The choice of the utilization as the reference corresponds to the MADIFA (Mahalanobis distances factor analysis), which identifies the directions on which the available EUs are in average the furthest from the optimum of the niche, allowing habitat suitability modelling. The choice of the availability as the reference corresponds to the FANTER (Factor analysis of the niche, taking the environment as the reference), which identifies the directions on which the niche is the furthest from the average environment (marginality) and those on which the niche is the narrowest compared with the environment (specialization). The commonly used ENFA (Ecological niche factor analysis) is at the middle point between the MADIFA and the FANTER, considering both distributions as the reference and the focus simultaneously. When used concurrently, these three analyses allow an extensive exploration of the system.     

Quantitative structure-activity relationships for the pre-steady-state inhibition of cholesterol esterase by 4-nitrophenyl-N-substituted carbamates

4-Nitrophenyl-N-substituted carbamates (1-6) are the pseudo-substrate inhibitors of porcine pancreatic cholesterol esterase. Thus, the first step of the inhibition (Ki step) is the formation of the enzyme inhibitor tetrahedral adduct and the second step of the inhibition (kc) is the formation of the carbamyl enzyme. The formation of the enzyme inhibitor tetrahedral adduct is further divided into two steps, the formation of the enzyme-inhibitor complex with the dissociation constant, KS, at the first step and the formation of the enzyme-inhibitor tetrahedral adduct from the complex at the second step. The two-step mechanism for the formation of the enzyme-inhibitor tetrahedral adduct is confirmed by the pre-steady-state kinetics. The results of quantitative structure-activity relationships for the pre-steady-state inhibitions of cholesterol esterase by carbamates 1-6 indicate that values of -logKs and logk2/k-2 are correlated with the Taft substituent constant, sigma*, and the rho* values from these correlations are -0.33 and 0.1, respectively. The negative rho* value for the -logKS-sigma*-correlation indicates that the first step of the two-step formation of the enzyme-inhibitor tetrahedral adduct (KS step) is the formation of the positive enzyme inhibitor complex. The positive rho* value for the logk2/k-2 -sigma*-correlation indicates that the enzyme inhibitor tetrahedral adduct is more negative than the enzyme inhibitor complex. Finally, the two-step mechanism for the formation of the enzyme inhibitor tetrahedral adduct is proposed according to these results. Thus, the partially positive charge is developed at nitrogen of carbamates 1-6 in the enzyme-inhibitor complex probably due to the hydrogen bonding between the lone pair of nitrogen of carbamates 1-6 and the amide hydrogen of the oxyanion hole of the enzyme. The second step of the two-step formation of the enzyme-inhibitor tetrahedral adduct is the nucleophilic attack of the serine of the enzyme to the carbonyl group of carbamates 1-6 in the enzyme-inhibitor complex and develops the negative-charged oxygen in the adduct.     

Linkage between parasternals and external intercostals during resting breathing

To assess the mechanical coupling between the parasternal and external intercostals in the cranial portion of the rib cage, we measured the respiratory changes in length and the electromyograms of the two muscles in the same third or fourth intercostal space in 24 spontaneously breathing dogs. We found that 1) the amount of inspiratory shortening of the external intercostal was considerably smaller than the amount of shortening of the parasternal; 2) after selective denervation of the parasternal, the inspiratory shortening of both the parasternal and the external intercostal was almost abolished; 3) on the other hand, after selective denervation of the external intercostal, the inspiratory shortening of the parasternal was unchanged, and the inspiratory shortening of the external intercostal was reduced but not suppressed; and 4) this persistent shortening of the external intercostal was reversed into a clear-cut inspiratory lengthening when the parasternal was subsequently denervated. We conclude that in the dog 1) the inspiratory contraction of the external intercostals in the cranial portion of the rib cage is agonistic in nature as is the contraction of the parasternals; 2) during resting breathing, however, the changes in length of these external intercostals are largely determined by the action of the parasternals. These observations are consistent with the idea that in the dog, the parasternals play a larger role than the external intercostals in elevating the ribs during resting inspiration.